Applied Surface Science (v.258, #20)

Graphene supported nano particles of Pt–Ni for CO oxidation by Cheng Zhang; Wei Lv; Quanhong Yang; Yuan Liu (7795-7800).
► Graphene supported Pt, Ni and Pt–Ni nano particles synthesized by impregnation. ► Catalysts for CO oxidation. ► Metal particles highly dispersed on the graphene sheets with small average particle size. ► Pure graphene is inactive for CO oxidation. ► Supported Pt–Ni catalyst showed the best activity owing to the formation of Pt–Ni alloy on the graphene sheets.In this study, a series of graphene supported Pt, Ni and Pt–Ni nano particles were successfully synthesized by a simple impregnation method. The resultant composites were characterized using SEM, XRD, HRTEM, XPS and TPR techniques and their catalytic performance for the oxidation of carbon monoxide was tested. It was shown that in the prepared metal/graphene composite, metal particles were highly dispersed on the graphene sheets (GS) with an average particle size of 1–3 nm. The results of catalytic performance tests indicate that the activity decreases in the order of Pt–Ni/GS, Pt/GS and Ni/GS. In the sample of Pt–Ni/GS, Pt–Ni alloy was formed, which contributed to the high activity of Pt–Ni/GS for CO oxidation.
Keywords: Graphene; Pt–Ni; CO oxidation; Metal/graphene composite;

Chitosan/poly (vinyl pyrollidone) coatings improve the antibacterial properties of poly(ethylene terephthalate) by Bai-liang Wang; Jin-lei Wang; Dan-dan Li; Ke-feng Ren; Jian Ji (7801-7808).
► CHI/PVP coatings were coated on pretreated PET to enhance the binding capacity of the coatings. ► CHI/PVP coatings have favorable bactericidal activity towards Staphylococcus aureus and Escherichia coli. ► Increasing PVP amount obviously reduce adhesion of bacteria. ► Antibacterial mechanism study indicates a combined dissolution release and contact killing existing. ► CHI/PVP coatings have good biocompatibility towards human umbilical vein endothelial cells.Chitosan/poly (vinyl pyrollidone) (CHI/PVP) coatings were prepared to improve the antibacterial properties of poly (ethylene terephthalate) (PET) by a simple dip-coating method. The binding capability of CHI/PVP coatings was enhanced by successively pretreatment of PET by polyetherimide and polyacrylic acid and crosslinking. Measurements of water contact angle and atomic force microscope revealed that the coatings created a highly hydrophilic surface with low roughness. Adherences of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) on PET with CHI/PVP coating were significantly reduced. Bactericidal activity of CHI/PVP coatings was good against E. coli and S. aureus and the adding of PVP obviously increased its antiadhesion property. In vitro cytotoxicity tests, cell morphology and activity evaluation of human umbilical vein endothelial cells showed that CHI/PVP coatings had good biocompatibility.
Keywords: Chitosan; PVP; Antibacterial; Antiadhesion; Coating;

Influence of NiO anode buffer layer prepared by solution on performance of bulk-heterojunction solar cells by Kyung Ho Kim; Chiaki Takahashi; Takashi Okubo; Yoshio Abe; Midori Kawamura (7809-7812).
► Performances of BHJ solar cells using NiO films prepared by solution are discussed. ► NiO film thickness and crystalline phase affect the properties of solar cells. ► BHJ solar cells with 20-nm-thick nc-NiO film show best photovoltaic characteristics.We investigate the properties of NiO thin films prepared by sol–gel solution and the photovoltaic performance of bulk-heterojunction (BHJ) solar cells based on NiO thin films as anode buffer layers with various film thickness and amorphous–crystalline phase. Optoelectronic properties and surface morphology of NiO films strongly depend on the thickness and phase of the NiO. The performance of solar cells based on nanocrystaline (nc-) NiO exhibits better photovoltaic characteristics in comparison to those employing an amorphous (a-) NiO. The obtained power conversion efficiency (PCE, η) of a solar cell with a 20-nm-thick nc-NiO is 2.24%, with a short-circuit density (J SC) of 7.77 mA/cm2, open-circuit voltage (V OC) of 0.57 V, and fill factor (FF) of 0.50.
Keywords: Bulk-heterojunction solar cells; NiO; Anode buffer layer; Solution; Amorphous; Nanocrystalline;

A white-emitting ZnO–Au nanocomposite and its SERS applications by Lanlan Sun; Dongxu Zhao; Meng Ding; Haifeng Zhao; Zhenzhong Zhang; Binghui Li; Dezhen Shen (7813-7819).
Display Omitted► White-emitting ZnO–Au nanocomposites were synthesized by acid etching process. ► Thickness of Au NPs on ZnO surface is dependent on Au deposition time. ► PL of nanocomposites is affected by thickness of Au NPs on ZnO surface. ► ZnO/Au composite can be used as good SERS-active substrates.We reported a simple method to synthesize ZnO–Au nanocomposites (hybrid A) by combining hydrothermal and electric beam evaporation deposition method. It was found that Au deposition time takes an important role in the generation of Au nanoparticles. Changing Au deposition time makes the thickness of Au formed on ZnO nanorods increase from 10 nm to 70 nm. On the other hand, white-emitting ZnO–Au nanocomposites (hybrid B) were obtained after treating hybrid A with HCl solution. Thanks to the covering of Au film and acid etching, it induces many defects on the surface of ZnO NRs, and largely enhances the visible emission of surviving ZnO and finally generates white emission on Au mesocrystals (hybrid B). Both of the ZnO–Au hybrids (A and B) can be applied as substrates in surface-enhanced Raman scattering (SERS) measurement. A typical probe molecule, 4-ATP was used to test the SERS activity of the ZnO–Au composites and the results indicated good Raman activity on the substrates.
Keywords: ZnO–Au; Hybrid; White-emitting; SERS;

Effect of active screen plasma nitriding pretreatment on wear behavior of TiN coating deposited by PACVD technique by M. Raoufi; Sh. Mirdamadi; F. Mahboubi; Sh. Ahangarani; M.S. Mahdipoor; H. Elmkhah (7820-7825).
► Disc shaped samples were prepared from AISI H13 (DIN 1.2344) steel. ► Samples were exposed to active screen plasma nitriding (ASPN). ► TiN layer was deposited on all samples through PACVD technique. ► ASPN pretreatment prevents a very hard layer of 1810 Hv on a not so hard substrate. ► Weight loss of samples which had experienced ASPN pretreatment was very low.Titanium based alloys are used extensively for improving wear properties of different parts due to their high hardness contents. Titanium nitride (TiN) is among these coatings which can be deposited on surface using various techniques such as CVD, PVD and PACVD. Their weak interface with substrate is one major drawback which can increase the total wear in spite of favorite wear behavior of TiN. Disc shaped samples from AISI H13 (DIN 1.2344) steel were prepared in this study. Single TiN coating was deposited on some of them while others have experienced a TiN deposition by active screen plasma nitriding (ASPN). Hardness at the surface and depth of samples was measured through Vickers micro hardness test which revealed 1810 Hv hardness as the maximum values for a dual-layered ASPN–TiN. Pin-on-disc wear test was done in order to study the wear mechanism. In this regard, the wear behavior of samples was investigated against pins from 100Cr6 (Din 1.3505) bearing steel and tungsten carbide–cobalt (WC–Co) steel. It was evidenced that the dual-layer ASPN–TiN coating has shown the least weight loss with the best wearing behavior because of its high hardness values, stable interface and acceptable resistance against peeling during wearing period.
Keywords: CVD coatings; Wear testing; Hardness; Cutting tools;

Synthesis and photocatalytic activity of graphene/BiOBr composites under visible light by Xingmiao Zhang; Xiaofeng Chang; M.A. Gondal; Bin Zhang; Yousong Liu; Guangbin Ji (7826-7832).
► The graphene can accept the photoexcited electrons from BiOBr and thus inhibits the electron–hole recombination. ► The graphene significantly improved the photocatalytic activity under visible light irradiation. ► The photocatalytic activity of graphene/BiOBr strongly depend on the amount of graphene.The study presented in this work deals with the synthesis of graphene/BiOBr composite following hydrothermal reaction between graphene oxide and BiOBr. The results achieved demonstrated that the presence of graphene on the surface of BiOBr significantly improved the photocatalytic activity, under visible light irradiation, owing to the low isoelectric characteristics of graphene and better interfacial electron transfer between BiOBr and graphene. The effect of different amounts of graphene such as 1, 3, 6 and 10 wt% on the photocatalytic and adsorption efficiency was investigated. Our results showed that there exists an optimum concentration of graphene (∼6 wt%) for the best photocatalytic response of BiOBr which could be due to crucial energy dissipation. The photocatalytic and adsorption efficiency of the composites were investigated by studying the removal of Sulforhodamine 640 dye as a probe reaction.
Keywords: Graphene; BiOBr; Adsorption; Photocatalysis; Sulforhodamine 640;

Effect of hydroxyl group attachment on TiO2 films for dye-sensitized solar cells by Alagesan Subramanian; Hong-Wen Wang (7833-7838).
► A facile method is presented to attach OH groups on TiO2 photoelectrodes by thermal treatment in H2O2-saturated argon. ► More surface groups were generated by H2O2 treatment than by other previously reported methods. ► The amount of dye adsorption was increased and the efficiency of the DSSC was enhanced.The effect of hydroxyl group attachment on the nanocrystalline TiO2 photoelectrodes for the performance of dye-sensitized solar cells (DSSCs) was investigated. The photoelectrodes were prepared using commercial TiO2 nanoparticles (Degussa P25). Hydroxyl groups were attached to the TiO2 film using hydrogen peroxide by thermal treatment method and the OH-attached sample was compared with the untreated one. The FTIR spectra evidenced the presence of hydroxyl groups attached to the TiO2 nanoparticles. Thermogravimetric analysis showed that the sample treated with hydrogen peroxide was attached with higher weight percentage of hydroxyl groups. The photovoltaic characteristics of the as-prepared DSSCs were measured by an electrochemical analyzer under the standard AM 1.5 illumination of 100 mW/cm2 light source. The hydroxyl groups attached sample showed an enhanced performance of DSSC than that of the blank P25 film. It shows that higher amount of dye was adsorbed due to the surface hydroxyl groups on the H2O2-treated samples. Electrochemical impedance spectroscopy (EIS) measurement indicated that the electron lifetime for the H2O2-treated sample was longer than that of the untreated sample. The higher dye loading due to the attached hydroxyl groups on the sample was confirmed using UV–vis measurement.
Keywords: Hydroxyl; TiO2; Dye-sensitized solar cell;

Simonkolleite nano-platelets: Synthesis and temperature effect on hydrogen gas sensing properties by J. Sithole; B.D. Ngom; S. Khamlich; E. Manikanadan; N. Manyala; M.L. Saboungi; D. Knoessen; R. Nemutudi; M. Maaza (7839-7843).
► The crystallinity indicates that the plate-like Zn5(OH)8Cl2·H2O possessed a smooth surface. ► The fast responses and high sensitivity due to high polarity and/or porosity in plate-like structure of simonkolleite sample. ► The sensitivity ΔR/R of our sensor is attractive for further investigation for practical H2 sensor applications. ► The simonkolleite Zn5(OH)8Cl2·H2O nano-platelets revealed a significant and singular H2 gas sensing characteristics.In this work, the new refined mineral platelets-like morphology of simonkolleite based particles described by Shemetzer et al. (1985) were synthesized in zinc nitrate aqueous solution by a moderate solution process. The morphological and structural properties of the platelets-like Zn5(OH)8Cl2·H2O were characterized by scanning electron microscope energy dispersed X-ray spectroscopy, transmission electron microscope, powder X-ray diffraction and selected area electron diffraction as well as attenuated total reflection infrared spectroscopy. The morphology as well as the size in both basal and transversal directions of the simonkolleite Zn5(OH)8Cl2·H2O nano/micro crystals was found to be significantly depending on the specific concentration of 0.1 M of Zn2+/Cl ions in the precursor solution. The simonkolleite Zn5(OH)8Cl2·H2O nano-platelets revealed a significant and singular H2 gas sensing characteristics. The operating temperature was found to play a key role on the sensing properties of simonkolleite. The effect of temperature on the simonkolleite sample as a hydrogen gas sensor was studied by recording the change in resistivity of the film in presence of the test gas. The results on the sensitivity and response time as per comparison to earlier reported ZnO based sensors are indicated and discussed.
Keywords: Nano-particles; Zinc oxide; Simonkolleite; Hydrothermal; Photonics and gas sensing;

Investigation of Se supply for the growth of Cu2ZnSn(S x Se1−x )4 (x  ≈ 0.02–0.05) thin films for photovoltaics by Jie Ge; Shaohua Zuo; Jinchun Jiang; Jianhua Ma; Lihong Yang; Pingxiong Yang; Junhao Chu (7844-7848).
► The Se supply for the selenization of CZTSSe films with high Se content was investigated. ► The CZTSSe precursors were electroplated on ITO coated glasses. ► An artfully designed graphite box was used as the selenization container. ► The usage amount of Se powder was optimized. ► The pressure of nitrogen in the tubular furnace was refined.In this work, the selenization growth of electrochemically deposited Cu2ZnSn(S x Se1−x )4 (CZTSSe) films with x  ≈ 0.02–0.05 was optimized by two groups of experiments in a graphite box. The selenization of CZTSSe is strongly dependent on the Se supply in the graphite box. Insufficient Se supply left the selenization incomplete. Higher Se supply to CZTSSe either by increasing the Se powder usage or by increasing the external pressure of nitrogen resulted in the degradation of CZTSSe films with lower degree of crystallinity. Our experimental results show that the refined usage amount of Se powder is 0.3 g and the optimized external pressure of flowing nitrogen in the furnace is from 0.5 Torr to 2 Torr. The characterization of XRD, Raman and SEM confirmed the films obtained under the best conditions were well-developed CZTSSe films with compact faceted grains and good crystallinity. Additionally, the CZTSSe film grown using 2 Torr of nitrogen pressure showed more orientation along (2 2 0/2 0 4).
Keywords: Cu2ZnSn(S x Se1−x )4; Solar cell absorber; Electroplating; ITO substrate; Selenization; Se supply;

Manufacture, microstructure and mechanical properties of W―Ta―N nano-structured hard films by J.F. Yang; Y. Jiang; Z.G. Yuan; X.P. Wang; Q.F. Fang (7849-7854).
Display Omitted► W―Ta―N hard films were sputter deposited on silicon substrate using direct current magnetron sputtering technique. ► W―Ta―N coatings were consisted of W―Ta―N solid solution face centered cubic structure. ► Hardness of W―Ta―N coatings reached maximum value of 38 GPa at the Ta content of 31 at.%. ► The adhesion strength of W―Ta―N coatings to substrate varied in the range of 27–35 N.W1−x Ta x N y (x  = 0–0.95) hard films were deposited on Si substrates using reactive direct current magnetron sputtering. The effect of tantalum concentration on phase composition, microstructure, surface morphology, adhesion strength, and hardness of the films has been studied by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, nano-indenter, and scratch tester. It was found that regardless of tantalum concentration all the W1−x Ta x N y films show face centered cubic structure, and form W―Ta―N solid solution. The hardness and Youngs’ modulus of W1−x Ta x N y films initially increase and then decrease with increasing tantalum concentration, after passing the maximum value of 38 GPa and 360 GPa at x  = 0.31, respectively. The adhesion strength of coating to silicon substrate is in the range of 27–35 N, no obvious variation trend of adhesion strength with tantalum concentration was observed.
Keywords: Tungsten tantalum nitride; Magnetron sputtering; Hardness; Adhesion strength;

► Nanostructured thin films of TiO2 prepared by swift heavy ion irradiation. ► Effect of Rapid Thermal Annealing (RTA) on nanostructured TiO2 thin films. ► Surface modification, structural and optical property change observed after RTA processing is attributed to defect annihilation.Irradiation by swift heavy ions (SHI) is unique tool to synthesize nanocrystalline thin films. We have reported transformation of 100 nm thick amorphous films into nanocrystalline film due to irradiation by 100 MeV Ag ion beam. Oblate shaped nanoparticles having anatase phase of TiO2 were formed on the surface of the irradiated films. In the present investigation, these films are annealed at 350 °C for 2 min in oxygen atmosphere by Rapid Thermal Annealing (RTA) method. During RTA processing, the temperature rises abruptly and this thermal instability is expected to alter surface morphology, structural and optical properties of nanocrystalline TiO2 thin films. Thus in the present work, effect of RTA on SHI induced nanocrystalline thin films of TiO2 is studied. The effect of RTA processing on the shape and size of TiO2 nanoparticles is studied by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Glancing Angle X-ray Diffraction (GAXRD) studies are carried to investigate structural changes induced by RTA processing. Optical characterization is carried out by UV–vis spectroscopy and photoluminescence (PL) spectroscopy. The changes observed in structural and optical properties of nanocrystalline TiO2 thin films after RTA processing are attributed to the annihilation of SHI induced defects.
Keywords: TiO2 nanoparticles; Electronic excitation; RTA annealing;

Effect of laser power on orientation and microstructure of Ba2TiO4 film prepared by laser chemical vapor deposition by Dongyun Guo; Takashi Goto; Chuanbin Wang; Qiang Shen; Lianmeng Zhang (7860-7863).
► The single orthorhombic phase Ba2TiO4 films were prepared by laser CVD. ► With increasing laser power, the preferred orientation of Ba2TiO4 film changed. ► With increasing laser power, the microstructure of Ba2TiO4 film changed. ► Ba2TiO4 film prepared at 881 K had high deposition rate of 51.4 μm h−1.Ba2TiO4 films were prepared on Pt/Ti/SiO2/Si substrates by laser chemical vapor deposition method. The effect of laser power (P L) on orientation and microstructure was investigated. With increasing P L from 52 to 93 W, the deposition temperature (T dep) increased from 845 to 946 K. With increasing T dep from 845 to 927 K, the preferred orientation of Ba2TiO4 films changed from (0 9 1) to (1 0 3), the surface morphologies changed from faceted to rectangular, and the columnar cross-section became thicker. The films prepared at high T dep (931–946 K) had the porous cross-section consisted of powder-like grains. Ba2TiO4 film prepared at 881 K had high deposition rate (R dep) of 51.4 μm h−1, which was advantageous to industrial production.
Keywords: Ba2TiO4 film; Laser chemical vapor deposition; Orientation; Laser power;

Bio-polymer coatings on neural probe surfaces: Influence of the initial sample composition by Winnie W.Y. Chow; Stanislav Herwik; Patrick Ruther; Emmanuelle Göthelid; Sven Oscarsson (7864-7871).
► Hyaluronic acid (HYA) was used as a coating material of neural probes. ► Probe surfaces were modified by (3-mercaptopropyl) methyldimethoxysilane (MPMDMS) and HyA was chemically functionalized with SS-pyridin group. ► The coated surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM).This paper presents the results of the study of hyaluronic acid (HyA) coating on two structural materials, silicon oxide (dielectric) surface and platinum (Pt) surface used for fabrication of probes developed for neurological investigations in the framework of the EU-project NeuroProbes. The silicon-based neural probes consist of multiple Pt electrodes on the probe shafts for neural recording applications. HyA coatings were proposed to apply on the probe surfaces to enhance the biocompatibility . This study aims at understanding the influence of the initial composition of the probe surface on the structure and morphology of HyA coating. HyA was chemically functionalized by SS-pyridin using (N-Succinimidyl 3-[2-pyridyldithio]-propionate) (SPDP) and was immobilized on the surfaces via a covalent bond. The dielectric and Pt surfaces were derivatized by use of (3-mercaptopropyl) methyldimethoxysilane (MPMDMS). The silanol groups in MPMDMS bind to the dielectric surface, leaving the thiol groups at the uppermost surface and the thiol groups then bind covalently to the functionalized HyA. On the Pt surface, it is the thiol group which binds on the Pt surface. The coated surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). A well-defined HyA layer was observed on both dielectric and Pt surfaces. The coating of two molecular weights (340 kDa and 1.3 MDa) of HyA was examined. The influence of the silanized layer on the HyA coating was also investigated.
Keywords: Hyaluronic acid; Silicon oxide; Platinum; Atomic force microscopy; X-ray photoelectron spectroscopy;

► Exposure time is favorable for a Porous skin and particle morphology in VIPS. ► Porous skin and particle morphology are beneficial to the hydrophobic surface. ► The micro-nano bionic spheres contribute to the high CA on the PVDF surfaces. ► Low surface energy also contributes to the high CA on the PVDF surfaces.The present investigation revealed how the surface morphology and hydrophobicity of polyvinylidene fluoride (PVDF) membranes, which were prepared via a vapor-induced phase separation (VIPS) method, were affected by the exposure time. The mass variation of the cast film was recorded. Membrane morphologies were observed by scanning electron microscopy (SEM) and thermal behaviors of membranes were examined by differential scanning calorimetry (DSC). Wide angle X-ray diffraction (WAXD) was employed to analyze the crystalline structures of the overall membranes and the surface layers. The results showed that different membrane morphologies and hydrophobicities could be obtained by changing the exposure time. A long exposure time facilitated the crystallization process, resulting in the formation of a porous skin and particle morphology, which increased the hydrophobicity of the surface. A short exposure time favored the formation of a digitate macrovoid and dense skin resulting from liquid–liquid phase separation in the immersion process, which reduced surface hydrophobicity. The water permeate flux in vacuum membrane distillation was greatly affected by the membrane porosity and surface hydrophobicity.
Keywords: Surface morphology; Hydrophobicity; Polyvinylidene fluoride membranes; Vapor-induced phase separation; Vacuum membrane distillation;

Stability of hexa(ethylene glycol) SAMs towards the exposure to natural light and repeated reimmersion by Stefan Zorn; Ulf Dettinger; Maximilian W.A. Skoda; Robert M.J. Jacobs; Heiko Peisert; Alexander Gerlach; Thomas Chassé; Frank Schreiber (7882-7888).
► Degradation of hexa(ethylene glycol) SAMs within one week by exposure to natural light. ► High conformational stability of the SAMs over 3 months when they are stored in the dark. ► Conformational but not chemical changes of the SAMs by repeated reimmersion in EtOH.We investigate the stability of HS―(CH2)11 ―(OCH2CH2)6 ―CH3 self assembling monolayers (hexa(ethylene glycol) SAMs) on gold regarding reimmersion and exposure to natural light over long periods of time up to several months. With polarisation modulation infrared spectroscopy we were able to monitor significant changes in the fingerprint region (900–1800 cm−1) of the absorption modes of the SAMs, starting after a few days of exposure to natural light. We observed an exponential intensity decrease of modes indicating helical conformation of the SAM, as well as an exponential increase of modes indicating esters and formates suggesting a degradation of the SAM. X-ray photoelectron spectra of carbon C1s and sulphur S2p confirm the chemical nature of those changes. SAMs stored without light exposure show a drastically decreased change in the infrared spectra. In addition, we could find substantial conformational changes upon repeated drying and reimmersion in EtOH, manifesting in an intensity decrease of the absorption modes indicating hexa(ethylene glycol) molecules in helical conformation. Since the XPS data do not show changes in the chemical structure, we assume disordering effects and dissolution of molecules in solution. Our results suggest that SAMs can be stored over long periods of time in air without major changes if light exposure is avoided.
Keywords: Self assembling monolayers; Polarisation modulation infrared spectroscopy; Degradation; XPS; Thiol SAMs; Stability;

Physico-chemical characterization of functionalized polypropylenic fibers for prosthetic applications by Roberto Nisticò; Maria Giulia Faga; Giovanna Gautier; Giuliana Magnacca; Domenico D’Angelo; Emanuele Ciancio; Giacomo Piacenza; Roberta Lamberti; Selanna Martorana (7889-7896).
► Polypropylene mesh was plasma activated and covered by a chitosan layer to induce antibacterial properties. ► A single crystalline isotactic phase for polypropylene fibers (α phase) was observed by XRD and DSC. ► Infrared spectroscopy showed the PP fibers surface oxidation after plasma treatment and the effective presence of chitosan. ► Chitosan was released in the first few days of soaking, i.e. during the period in which infections usually occur after prosthesis implant.Polypropylene (PP) fibers can be manufactured to form nets which can find application as prosthesis in hernioplasty.One of the most important problem to deal with when nets are applied in vivo consists in the reproduction of bacteria within the net fibers intersections. This occurs right after the application of the prosthesis, and causes infections, thus it is fundamental to remove bacteria in the very early stage of the nets application.This paper deals with the physico-chemical characterization of such nets, pre-treated by atmospheric pressure plasma dielectric barrier discharge apparatus (APP-DBD) and functionalized with an antibiotic drug such as chitosan.The physico-chemical characterization of sterilized nets, before and after the functionalization with chitosan, was carried out by means of scanning electron microscopy (SEM) coupled with EDS spectroscopy, FTIR spectroscopy, drop shape analysis (DSA), X-ray diffraction and thermal analyses (TGA and DSC).The aim of the work is to individuate a good strategy to characterize this kind of materials, to understand the effects of polypropylene pre-treatment on functionalization efficiency, to follow the materials ageing in order to study the effects of the surface treatment for in vivo applications.
Keywords: Hernia; Fiber; Polypropylene; Chitosan deposition; Activating plasma treatment;

Plasma process for development of a bulk heterojunction optoelectronic device: A highly sensitive UV detector by Shyamalima Sharma; Arup R. Pal; Joyanti Chutia; Heremba Bailung; Neelotpal S. Sarma; Narendra N. Dass; Dinkar Patil (7897-7906).
Deposition of composite thin film of polyaniline/TiO2 (PAni/TiO2) has been carried out by a combined process of magnetron sputtering and plasma polymerization at a pressure of 5 × 10−2  Torr using titanium as target material for sputtering, aniline as monomer, oxygen as reactive gas and argon as carrier gas/ion source for sputtering. The deposition has been achieved using dc discharge power of 35 W for sputtering and radio frequency (rf) power of 8–12 W at substrate bias values in the ranges of −80 to −100 V for polymerization. The ultraviolet (UV) photo-stability of the composite film has been studied by exposing the film deposited on silicon substrate for different reaction times up to 1 h under UV radiation at wave length range of 280–400 nm with intensity 0.4 mW/cm2. An organic/inorganic nanocomposite film based photovoltaic device has been developed. The device has an aluminum/composite/indium tin oxide sandwiched structure that shows strong photoresponse in ultraviolet region and hence the device has potential for application as an UV detector.Display Omitted► Polyaniline/TiO2 (PAni/TiO2) film has been deposited by a combined process of magnetron sputtering and plasma polymerization. ► An organic/inorganic nanocomposite film based photovoltaic device is developed. ► The device has an aluminum/composite/indium tin oxide sandwiched structure. ► The device shows strong photo-response in ultraviolet region, so it has potential for application as an UV detector.Deposition of composite thin film of polyaniline/TiO2 (PAni/TiO2) has been carried out by a combined process of magnetron sputtering and plasma polymerization at a pressure of 5 × 10−2  Torr using titanium as a target material for sputtering, aniline as monomer, oxygen as reactive gas and argon as carrier gas/ion source for sputtering. The deposition has been achieved using direct current (dc) discharge power of 35 W for sputtering and radio frequency (rf) power of 8–12 W at substrate bias values in the ranges of −80 to −100 V for polymerization. The composition of the film has been studied using infrared spectroscopy, Raman spectroscopy as well as X-ray photoelectron spectroscopy. The morphology of the film has been characterized with the help of a transmission electron microscopy and atomic force microscopy. The ultraviolet (UV) photo-stability of the composite film has been studied by exposing the film deposited on silicon substrate for different reaction times up to 1 h under UV radiation at wave length range of 280–400 nm with an intensity of 0.4 mW/cm2. An organic/inorganic nanocomposite film based photovoltaic device has been developed. The device has an aluminum/composite/indium tin oxide sandwiched structure that shows strong photoresponse in ultraviolet region and hence the device has potential for application as an UV detector.
Keywords: Plasma polymerization; Magnetron sputtering; Conducting polymer nanocomposite; Organic photovoltaic device;

Facile approach for preparation of stable water-repellent nanoparticle coating by Xia Zhang; Yonggang Guo; Zhijun Zhang; Pingyu Zhang (7907-7911).
► Fluorine-free superhydrophobic nanoparticle coating was fabricated by a simple dip-coating method without any chemical modification. ► The surfaces retained good superhydrophobic stability in long-term storage with a high water contact angle and a low sliding angle. ► The superhydrophobic surface possessed good adhesion strength to substrate and mechanical stability, which would enhance its potential for practical application.The present study reports a very simple and low-cost dip-coating method for the preparation of fluorine-free water-repellent SiO2 nanoparticle coating. The coating has a high water contact angle of 169° and a sliding angle of 7°, showing superhydrophobic property. The coating demonstrates good adhesion on substrates and the long-term stability. Importantly, the coating also demonstrates superhydrophobicity in the wide pH range of corrosive liquids. It is found that a piece of glass coated with superhydrophobic coatings cannot only float freely on water surface but also exhibit striking loading capacities.
Keywords: Superhydrophobic; SiO2 nanoparticles; Coating;

Display Omitted► Purified and functionalized in HNO3 ox-MWCNTs - thermal properties. ► Electron spectroscopy (XPS, REELS) and mass spectroscopy. ► Desorption of H2, H2O, CO and CO2. ► Decomposition of COOH, C(O)―O―(O)C, C―OH, C=O groups and organic acid impurities. ► Water and organic acid impurities remain mainly at the surface.Purified and functionalized in boiling concentrated (68%) HNO3 acid the oxidized multiwall carbon nanotubes (ox-MWCNTs) under thermal treatment from RT to 630 °C and at 350 °C time dependent (1–4 h) were investigated using the surface sensitive electron and mass spectroscopy methods.Mass spectroscopy indicates significant desorption of H2 and H2O to about 300 °C. Higher H2 desorption rate from RT up to about 100 °C is most likely caused by decomposition of organic acid impurities included within a bundle and in channels of the ox-MWCNTs after their functionalization by HNO3. In the range of 100–300 °C part of the detected H2, accompanied by desorption of CO2, may origin from desorbed water. Above 300 °C, the small amount of desorbing H2O may result from transformation of carboxylic groups into carboxylic acid anhydride. Significant desorption of CO2 starting from 150 °C may result from decomposition of carboxylic groups, whereas desorption of CO starting at about 300 °C from decomposition of acid anhydride groups created from carboxylic groups during thermal dehydration. Desorption of CO and CO2 at about 470 °C may be due to decomposition of hydroxyl O―H and carbonyl C=O groups. Above 600 °C mainly decomposition of C=O groups takes place and results in small desorption of CO. Time dependent (1–4 h) thermal treatment of ox-MWCNTs at 350 °C shows in XPS spectra decreasing amount of C―O in carboxyl groups and increasing amount of C=O in carbonyl and acid anhydride groups arising from carboxyl groups decomposition. Between 350 °C and 470 °C the higher desorption rate of CO2 than CO indicates significant decomposition of carboxyl and carboxyl anhydride groups. At 350 °C the dynamic changes are indicated by the energy, intensity and full width at half maximum (FWHM) of the π → π* interband transition and π loss peak, and quasi-elastic peak FWHM. During 4 h at 350 °C no C sp2 reconstruction is observed. For the applied procedure of MWCNTs oxidation, large amount of water and some organic acid impurities, resulting from the MWCNTs oxidation, remain in the CNTs channels, interstitial channels between tubes and at nanotubes surface.
Keywords: MWCNTs; Ox-MWCNTs; Functionalization; Functional materials; Reconstruction; Electron spectroscopy; Mass spectroscopy;

The preparation of Al-containing amorphous carbon nanotip arrays and their excellent field emission properties by Zhiguo Wu; Weihua Li; Liang Xu; Shuankui Li; Chunyu Zhang; Pengxun Yan (7918-7921).
► Large scale Al containing amorphous carbon nanotip arrays with uniform size and high density were obtained through filtered cathodic arc plasma technique via a specially widened anodic aluminum oxide pore arrays as templates. ► The content of sp3 increased with the increased content of Al containing in the amorphous carbon film. ► The threshold field decreased to 0.32 V/μm at 10 mA/cm2 and the maximum emission current density increased to 72 mA/cm2 at Al content of 6.38 at%.Large scale Al-containing amorphous carbon (a-C:Al) nanotip arrays with uniform size and high density were obtained through filtered cathodic arc plasma (FCAP) technique via a specially widened anodic aluminum oxide (AAO) pore arrays as templates. The nanotip is about 100 nm in diameter at the bottom and 120 nm in height with density of 1010  cm−2. It was found that the sp3/(sp3  + sp2) ratio were 60.2%, 64.0%, 65.1% and 67.2% for Al content of 0.94 at%, 3.85 at%, 5.33 at% and 6.38 at%, respectively. The threshold field decreased to 0.32 V/μm at 10 mA/cm2 and the maximum emission current density increased to 72 mA/cm2 at Al content of 6.38 at%. This kind of material will play a significant role in cold-cathode field emission display area.
Keywords: Nanotip arrays; Anodic aluminum oxide; Filtered cathodic arc plasma; Field emission;

A mild l-cystine-assisted hydrothermal route to metastable γ-MnS multipods by Meiying Liu; Nannan Shan; Linlin Chen; Xiaoqian Li; Bona Li; Wansheng You (7922-7927).
► γ-MnS multipods consisting of hexagonal prism-like rods were produced by a novel biomolecule-assisted hydrothermal approach using l-cystine as both the sulfur source and complexing agent. ► γ-MnS single-crystal rods preferentially grow along the c-axis [1 0 0] direction. ► The room-temperature PL spectrum shows a strong emission peak at 419 nm corresponding to the MnS band edge emission.A facile biomolecule-assisted hydrothermal route has been demonstrated to grow γ-MnS multipods at 130 °C for 10 h in distilled water when l-cystine was used as both the sulfur source and complexing agent. The products were characterized by XRD, SEM, TEM and photoluminescence. The results indicate that the as-synthesized γ-MnS multipods are composed of single-crystal, hexagonal and prism-like rods with a size of ca. 300–800 nm and a length of 2–4 μm. The room-temperature photoluminescence spectrum exhibits a peak centered at 419 nm corresponding to the band edge emission when the sample was excited with a wavelength of 358 nm. A possible formation mechanism for the γ-MnS multipods was also discussed based on the time-dependent experiments.
Keywords: γ-MnS multipods; l-Cystine; Hydrothermal;

Online surface characterization of paper and paperboards in a wide-range of the spatial wavelength spectrum by Anzar Alam; Jan Thim; Mattias O’Nils; Anatoliy Manuilskiy; Johan Lindgren; Joar Lidén (7928-7935).
► Online surface characterization of 8 reels of paper and paperboard was presented. ► Both sides of newspaper and uncoated and coated sides of paperboard were studied. ► Topography was analysed in a wide range of wavelength spectrum from 0.1 to 10 mm. ► Fine coated edge and middle position paperboard were successfully characterized. ► Adopted line-triangulation method can be a valuable application in paper industry.In the paper industry, surface topography is the essence of both paper and paperboard, and accurate topographical measurements are equally essential in order to achieve a uniform smooth surface. The traditional laboratory methods measure only a few samples from the entire tambour and there are other obvious limitations to this approach. Online measurements may be of significant value to improve the surface quality throughout the production. Roughness is one of the topography components and the majority of techniques measure paper by means of a single predictor of average roughness, R a which is inadequate in providing a comprehensive characterization of the surface. Measurements, in a wide range of wavelengths, can characterize topography components such as roughness, waviness, cockling, etc. Online measurements were taken for various grades of 8 paper reels, containing the wireside and topsides for newspaper, and uncoated and coated sides of paperboards. Their surface characterization, in the spatial wavelength spectrum, from 0.1 to 10 mm was obtained. This article presents the online characterization results which have efficiently distinguished the surfaces of same family materials including the edge and the middle position reels of fine coated paperboard. Online measurements were taken, at Iggesund Paperboard Pilot Coater in Sweden, by using a recently developed Online Topography (OnTop) device which is based on the principle of light triangulation.
Keywords: Online topography; Online paper measurements; Surface characterization; Paper spectral topography; Newspaper; Paperboard;

► Electrophoretic depositon technique was utilised for the catalyst preparation. ► CNTs was obtained over cobalt coated Stainless steel plate by CVD. ► High quality MWCNTs is obtained at 700 °C using hydrogen to acetylene gas ratio at 25:25 Sccm.Electrophoretic deposition was carried out to prepare cobalt catalyst layer over stainless steel for the growth of multi-walled carbon nanotubes (MWCNTs) via chemical vapour deposition. The effects of temperatures (700, 800 and 900 °C) and gas ratio of hydrogen to acetylene (0:50, 25:25 and 40:10 sccm) on the growth of carbon nanotubes (CNTs) were investigated. The morphology and crystalline nature of the purified CNTs were examined with scanning and transmission electron microscopy, and Raman spectroscopy. MWCNTs with high yield was grown on cobalt coated stainless steel at 700 °C, using hydrogen to acetylene gas ratio of 25:25 sccm. Electrophoretic deposition was demonstrated to be a simple technique for the catalyst preparation, which in turn makes the growth of CNTs economical and scalable.
Keywords: Carbon nanotubes; Electrophoresis; Chemical vapour deposition;

Wettability alteration by trimeric cationic surfactant at water-wet/oil-wet mica mineral surfaces by Rui Zhang; Ni Qin; Lin Peng; Ke Tang; Zhongbin Ye (7943-7949).
The reverse concentration of trimeric cationic surfactant is significantly low. ► The wettability is dependent on the adsorption areas of surfactant. ► The wettability of the surfactant is independent of surface tension.The wettability of oil reservoir rock affects the efficiency of the oil recovery process by reducing the capillary force. Methyldodecylbis [2-(dimethyldodecylammonio) ethyl] ammonium tribromide is a trimeric cationic surfactant that contains three dodecyl chains and three quaternary ammonium head groups connected by divinyl groups. The surfactant was synthesized, purified and used as a new wetting alteration agent. This paper focuses on the ability of this trimeric cationic surfactant to alter the wettability of water-wet and oil-wet mica mineral surfaces. The contact angle data of the solid–liquid interface in oil/water/solid three-phase system show that the trimeric cationic surfactant, when compared with single- and double-chain cationic surfactant, is a more effective wetting agent for water-wet and oil-wet mica surfaces at lower concentration. Measurements by atomic force microscopy (AFM) show that the surfactant molecules have formed a monolayer to reverse the wetting properties. On the water-wet surface, the surface is suffused with negative charge, which could attract the cationic head of surfactant, and leave the hydrophobic tails exposed. In contrast, on the oil-wet surface, the hydrophobic tails were attracted by hydrophobic interactions to the oil film between the surfactant and the crude oil. The hydrophilic heads were left outside to form a hydrophilic layer, which could explain the wettable to hydrophilic trend. Alteration to the degree of wettability is mainly dependent on the adsorption areas of the surfactant. The data show that the ability of the trimeric cationic surfactant affect the wettability is independent of surface tension.
Keywords: Trimeric cationic surfactant; Wettability; Contact angle; Atomic force microscopy;

Display Omitted► TiO2 nano particles were bonded to the hydroxyl groups of oligomer TMPSi. ► Functionalized NPs formed micro and nano structured aggregates during casting. ► The solvent used determined the superhydrophobic surface properties. ► Solvent xylene: self-cleaning surface. Solvent water: high adhesion. ► High contact angle hysteresis (aqueous solvent) was due to free OH groups on the surface.The present paper reports the preparation of very simple and inexpensive superhydrophobic surfaces fabricated using titanium dioxide and lower alkyl chain silane (trimethoxypropyl silane) in aqueous or non-aqueous solvent. The superhydrophobic surfaces fabricated in aqueous or non-aqueous solvent had same static water contact angle, but showed different contact angle hysteresis and liquid–solid adhesion. Superhydrophobic surface fabricated in aqueous solvent showed high contact angle hysteresis (CAH). In addition, liquid–solid adhesion of superhydrophobic surface fabricated in aqueous solvent is different in which the water droplet roll on the surface but will not roll off out of the surface during tilting and fell down when turned upside down. The reason for such high contact angle hysteresis and novel liquid–solid adhesion behavior is explained on the basis of measurements on the superhydrophobic surface using water contact angle (WCA) data, profilometry, SEM images, XPS and FTIR-ATR analysis. These results are compared with the superhydrophobic surface fabricated in non-aqueous solvent which showed self-cleaning properties. Based on WCA, XPS and FTIR-ATR analysis, it is shown that the difference in the CAH is more chemical in origin than morphology.
Keywords: Superhydrophobic; TiO2; Trimethoxypropyl silane; Hysteresis; Adhesion;

► We deposited Ni–Fe-based amorphous composite coating using HPDL processing. ► High laser power resulted in high dilution ratio of the coating. ► Low dilution ratio resulted in high amorphous content in the coating. ► Microhardness of 1200 HV0.5 was obtained due to formation of amorphous phase.Ni–Fe–B–Si–Nb coatings have been deposited on mild steel substrates using high power diode laser cladding. Scanning laser beam at high speeds was followed to remelt the surface of the coatings. Different laser cladding powers in the range of 700–1000 W were used to obtain various dilution ratios in the coating. The dilution effect on the chemical characterization, phase composition and microstructure is analyzed by energy dispersive spectroscopy, X-ray diffraction and scanning-electron microscopy. The microhardness distribution of the coatings after laser processing is also measured. The results reveal that Ni-based amorphous composite coatings have successfully been fabricated on mild steel substrate at low dilution ratio when the cladding power was 700 W, 800 W and 900 W. While at high laser power of 1000 W, no amorphous phase was found. The coatings with low dilution ratio exhibit the highest microhardness of 1200 HV0.5 due to their largest volume fraction of amorphous phase.
Keywords: High power diode laser; Laser cladding; Remelting; Amorphous coating; Dilution;

► Deposit thin Ni–Co–P alloy layers with different concentration of Ni, Co and P on the silicon substrate. ► Use complete wet process for the diffusion barrier alloy deposition. ► The barrier properties degraded with increasing the concentration of Co i.e. decreasing the P. ► The lower Co and higher P contents alloy film act as a good diffusion barrier up to 500 °C.Ni–Co–P alloy films were deposited on silicon substrate by electroless technique for diffusion barrier application in copper interconnects technology. The composition of films was varied by varying the concentration of contents in electroless deposition baths. The thermal stability of the films was evaluated by the annealing of samples at elevated temperature and the samples were characterised by using X-ray diffractometer (XRD), four probe method and field-emission scanning electron microscope (FE-SEM). Results indicated that barrier properties degraded with increasing the concentration of Co i.e. decreasing the P. The lower Co and higher P contents alloy film act as a good diffusion barrier up to the 500 °C.
Keywords: Ni–Co–P; Diffusion barrier; Copper; Electroless;

Environmentally friendly process for nickel electroplating of ABS by M. Bazzaoui; J.I. Martins; E.A. Bazzaoui; A. Albourine (7968-7975).
► The PPy is deposited chemically to transform ABS plastic conductor. ► Polymeric coating is homogeneous and adherent. ► Copper electroplating is successfully achieved on PPy/ABS. ► Nickel is deposited on Cu/PPt/ABS. ► SEM analysis shows that increasing the current density increases the copper and nickel thickness and enhances the copper particle texture.Nickel electroplating of acrylonitrile butadiene styrene (ABS) plastic has been achieved successfully without any chromium or palladium pretreatment. Once the ABS is coated with polypyrrole (PPy), the sample may be electroplated. The process is fast, economic and involves three stages. Firstly, chemical deposition of PPy on ABS, secondly, copper deposition and finally nickel electroplating. A homogenous and adherent PPy has been synthesized chemically on ABS plate by using pyrrole as monomer and iron (III) chloride as oxidant. Copper and nickel were deposited galvanostatically from industrial plating baths. The metallic coatings were homogeneous and the adherence was estimated at 100%. The thickness of copper and nickel depend on the electrolysis time. As the current density increases, the Cu and Ni thickness raises. This result was confirmed from SEM characterization and RX map. The Ni coating is characterized by a globular structure with globules of different sizes. Energy dispersive X-ray spectroscopy (EDS) analysis shows the presence of Ni with some amount of carbon and oxygen due to the nickel oxides and contaminant from the bath solution.
Keywords: ABS; Metallization; Conducting polymers; Electroplating;

L10 PtFe with (2 0 0) preferred orientation was obtained by annealing at only 500 °C. ► Rougher substrate surface inhibits formation of bigger columnar grains in Pt layer. ► Smaller columnar grains in Pt layer induce L10 PtFe with (2 0 0) preferred orientation. ► Magnetic coercivity of 3 layers L10 PtFe in and out plane models was 3.7 and 2.3 kOe.The Fe/Pt/Fe/Pt layers (Pt/Fe multilayer) were deposited on general glass substrate at room temperature by magnetron sputtering technique. Varying the deposition and post-annealing treatment parameters, the PtFe alloy (PtFe) layer with different crystal structures and magnetic properties were obtained at the interface between Fe and Pt layer. The characterization by X-ray diffraction (XRD) showed that the as-deposited Pt/Fe multilayer only contained pure Fe and Pt with body-centered and face-centered cubic structures, respectively. As-deposited Pt layer displayed (2 0 0) preferred orientation, and the columnar grains structure could be observed by the scanning electron microscopy. The PtFe layers with L10 face-centered cubic structure could be formed at the interface between Pt and Fe layers by post-annealing the multilayers at 500 °C. In case of Pt/Fe multilayer deposited on smooth substrate, the larger columnar grains in Pt layer resulted in L10 PtFe layers without any preferred orientation. While in case of Pt/Fe multilayer deposited on the rough substrate, the thinner columnar grains in Pt layer could induce L10 PtFe layers with (2 0 0) preferred orientation. In this case, the vibrating sample magnetometer results indicated that, the magnetic coercivity in plane and out-of-plane model could reach 3.72 and 2.32 kOe, respectively. Based on above results, the L10 structure Pt/Fe multilayer with satisfied magnetic properties could be prepared at low temperature by our simple route.
Keywords: Pt/Fe multilayer; L10 PtFe; Surface roughness; Crystal structure; Magnetic property;

Production of porous PTFE–Ag composite thin films by pulsed laser deposition by Gabriella Kecskeméti; Béla Hopp; Tomi Smausz; Zsolt Tóth; Gábor Szabó (7982-7988).
► PTFE–Ag composite thin films were prepared by pulsed laser deposition. ► Wettability of the prepared porous layers was increased. ► Increasing the silver content of the target the resistance of the films decreased. ► Prepared composite layers may use in sensor technology.The suitability of pulsed laser deposition technique for preparation of polytetrafluoroethylene (PTFE) and silver (Ag) composite thin films was demonstrated. Disk-shaped targets combined from silver and Teflon with various percentages were ablated with pulses of an ArF excimer laser. The chemical composition of the deposited layers was estimated based on deposition rates determined for the pure PTFE and Ag films. EDX and SEM analyses using secondary electron and backscattered electron images proved that the morphology of the layers is determined by the PTFE which is the main constituent and it is transferred mostly in form of grains and clusters forming a sponge-like structure with high specific surface. The Ag content is distributed over the surface of the PTFE structure. Contact angle measurements showed that with increasing the amount of Ag in the deposited layers the surface significantly enhanced the wetting properties. Conductivity experiments demonstrated that when the average silver content of the layers was increased from 0.16 to 3.28 wt% the resistance of our PTFE–Ag composite films decreased with about three orders of magnitudes (from ∼10 MΩ to ∼10 kΩ). The properties of these films suggest as being a good candidate for future electrochemical sensor applications.
Keywords: Pulsed laser deposition; Polytetrafluoroethylene (PTFE); Silver (Ag); Composite film; Resistance; Sensor technology;

Display Omitted► By using a ramp-cooling process to nucleate Si seeds on Si (1 1 1) based on the principle of liquid phase epitaxy (LPE), almost 100% vertically-aligned SiNWs can be reliably achieved on Si (1 1 1). ► The degree of vertical alignment is highly dependent on the cooling process. ► The percentages of vertically-aligned SiNWs are 30%, 55%, 70% and almost 100% for the cases without ramp cooling and with cooling at the rates of 50 °C/min, 30 °C/min and 10 °C/min, respectively.We have grown silicon nanowires (SiNWs) on Si (1 1 1) substrates by gold-catalyzed vapor–liquid–solid (VLS) process using tetrachlorosilane (SiCl4) in a hot-wall chemical vapor deposition reactor. Even under the optimized conditions including H2 annealing to reduce the surface native oxide, epitaxial SiNWs of 150–200 nm in diameter often grew along all four 〈1 1 1〉 family directions with one direction vertical and three others inclined to the surface. Therefore, the growth of high degree ordered SiNW arrays along [1 1 1] only was attempted on Au-coated Si (1 1 1) by a ramp-cooling process utilizing the liquid phase epitaxy (LPE) mechanism. The Au-coated Si substrate was first annealed in H2 at 650 °C to form Au–Si alloy nanoparticles, and then ramp-cooled at a controlled rate to precipitate epitaxial Si seeds on the substrate based on LPE mechanism. The substrate was further heated in SiCl4/H2 to 850 °C for the VLS growths of SiNWs on the Si seeds. Thus, almost 100% vertically-aligned SiNWs along [1 1 1] only could be reproducibly grown on Si (1 1 1), without using a template or patterning the metal catalyst. The high-density vertically-aligned SiNWs have good potentials for solar cells and nano-devices.
Keywords: Liquid phase epitaxy; Epitaxial growth; Vertical alignment; Semiconductor quantum wires; Nanowires; Silicon;

Effect of nitrogen doping on anatase–rutile phase transformation of TiO2 by Xianzhong Bu; Gaoke Zhang; Chonghui Zhang (7997-8001).
► N–TiO2 nanoparticles were prepared by hydrolysis of TiCl4 and urea. ► The phase transformation temperature of anatase to rutile was found to be increased by N-doping. ► The mechanism for the transformation temperature increase was summarized as the effects of the similar structure of titanium nitride and anatase, the crystal aberration and the retained crystal growth induced by N-doping. ► N-doped TiO2 showed much higher visible light photocatalytic activity in comparison with P25. The higher photocatalytic efficiency could be attributed to the synergetic effect of N-doping and appropriate crystallinity of anatase phase TiO2.N–TiO2 nanoparticles were prepared by hydrolysis of TiCl4 and characterized by means of XPS, SEM, XRD, TG-DSC and UV–vis DRS. The nitrogen was doped into TiO2 lattice successfully, and the temperature of anatase phase transforming to rutile phase was found to be increased by N-doping. By comparison of the crystal structure of titanium nitride, anatase and rutile, the mechanism for the transformation temperature increase was summarized as the effects of the similar structure of titanium nitride and anatase, the crystal aberration and the retained crystal growth induced by N-doping. The visible light photocatalytic activity of N-doped TiO2 was much higher in comparison with that of P25. The higher photocatalytic efficiency could be attributed to the synergetic effect of N-doping and appropriate crystallinity of anatase phase TiO2.
Keywords: N-doping; Phase transformation; TiO2; Photocatalyst;

Microstructuring and doping of silicon with nanosecond laser pulses by Xiaohong Li; Liyang Chang; Rong Qiu; Cai Wen; Zhihui Li; Sifu Hu (8002-8007).
► The low frequency ns laser is used to structure a large area silicon surface efficiently. ► The three types of structures are found in the structured surface. ► The dependence of optical and electronic properties on scanning speed and laser pulse energy are shown. ► The structured surface is crystalline and the sulfur element is found in the shallow surface up to about one micrometer in depth.We microstructure and dope silicon surfaces in SF6 atmosphere using nanosecond Nd:YAG laser pulses. The effects of scanning speed and laser pulse energy on surface morphology, optical and electronic properties of laser treated silicon are studied. When the scanning speed is 0.2 mm/s and the laser energy is 290 mJ, the absorptance of microstructured silicon can reach 90% in the visible spectrum and 80% in the infrared spectrum. In addition, its Hall mobility is measured as about 600 cm2  V−1  s−1. The electron diffraction shows that the irradiated silicon surface is crystalline and no disordered surface layer is found, which is good for optoelectronic applications.
Keywords: Silicon; Nanosecond laser pulse; Microstructuring; Doping; Optical properties; Electronic properties;

Electrodeposition and electrocatalytic activity of Cu2O film on stainless steel substrate by Mi Bao; Dan Wang; Shengyan Liu; Lili Kuang; Jian Sun; Fan Wang; Yanxuan Wen (8008-8014).
Display Omitted► Cu2O films via electrodeposition in simple Cu(II) electrolytes without any capping agent used. ► The orientation and morphology change of Cu2O films tuned by different anions is discussed. ► A distinctive change in orientation of Cu2O film with the deposition time. ► The activities of the obtained Cu2O films in degradation of methylene blue in water.The chemical nature of electrolytes, particularly anions, plays important roles in crystal growth in the electrodeposition process, and is responsible for the distinct growth behavior of crystals as well. In this work, Cu2O films with different orientations and morphologies were prepared through a simple electrodeposition approach onto stainless steel without any template or surfactant. A distinct change in the orientation of Cu2O film with deposition time is revealed via X-ray diffraction and scanning electron microscopy analysis. The morphology change in the Cu2O films tuned using different Cu(II) precursors is discussed. The orientation determines the crystallite morphology, enabling a direct control over the electrodeposition of Cu2O coatings. In addition, the electrocatalytic activities of the obtained Cu2O films in the degradation of organic contaminants in water are investigated.
Keywords: Cu2O; Electrodeposition; Morphology evolution; Electrocatalytic;

Photocatalytic activity of different morphologies TiO2 nanofibers by Shudan Li; Yihui Dong; Meirong Guo (8015-8018).
► Different morphologies TiO2 nanofibers were synthesized by electrospinning. ► Investigated the relationship between photocatalytic activity and morphology of TiO2 nanofibers. ► The ultrafine nanofibers show excellent photocatalytic activity.In this paper, one-dimensional TiO2 nanofibers were synthesized by electrospinning utilizing sol–gel precursors. The surface morphology, crystal structure and microstructure were investigated by scanning electron microscopy (SEM), Raman spectroscopy (Raman) and X-ray diffraction (XRD). The nanofibers with smaller diameter were continuously and uniformly distributed. The photocatalytic activity of different nanofibers was evaluated by degrading Methylene Blue (MB) solution. The effects of surface morphology on photocatalytic activity were mainly investigated. The results show that the ultrafine nanofibers exhibit higher photocatalytic activity, which is in good agreement with the characterization results. Moreover, the activity of all nanofibers is higher than that of commercial Degussa P-25 TiO2.
Keywords: Sol–gel preparation; Microstructure; TiO2; Electrospinning; Morphology;

Growth of carbon nanotubes from titanium dioxide nanoparticles by Qiran Cai; Yali Hu; Yunyun Liu; Shaoming Huang (8019-8025).
Display Omitted► TiO2 nanoparticles are active for CNTs growth. ► CNTs diameter depends on the size of TiO2 which can be controlled by sputtering time. ► SWNTs produced from TiO2 have narrow diameter distribution. ► In situ patterned SWNTs can be easily fabricated by sputtering approach.We have demonstrated that titanium dioxide (TiO2) nanoparticle is an efficient catalyst for the growth of carbon nanotubes (CNTs). TiO2 nanoparticles can be generated either by sol–gel method or sputtering. Highly dense single-walled carbon nanotubes (SWNTs) and/or multi-walled CNTs can be produced by ethanol-chemical vapor deposition (EtOH-CVD) using those TiO2 nanoparticles as catalysts. XPS measurements further prove that the TiO2 nanoparticles are responsible for the nanotube growth. Sputtering approach for generating TiO2 nanoparticles provide a facile way for patterning SWNTs for various applications.
Keywords: Metal-free growth; Carbon nanotube; Titianium oxide; Sputtering;

► Homogenously sized ZnO nanoparticles were synthesized via milling process. ► The UV blue shift resulted from the quantum size effect in the ZnO nanoparticle. ► The milling process had a significant effect on the grain crystallinity. ► Most optical properties were attributed to the defects introduced into the sample.Zinc oxide (ZnO) nanoparticles ranging ∼7–15 nm in size were successfully synthesized by the ball-milling technique. Mechanical milling was found very functional in producing ZnO nanoparticles with the possibility of obtaining large quantities. The milled nanoparticles were compared with commercial ZnO nanopowder. High-resolution scanning electron microscopy and atomic force microscopy analyses revealed a reduction in the lattice space and grain size with increased milling time, as well as severe lattice deformations in some of the nanoparticles. The milling process also had a significant effect on the grain crystallinity as illustrated by decreased lattice strain based on the X-ray diffraction lattice constant and full-wave at half-maximum data. The photoluminescence (PL) spectra of the ZnO powder showed a UV emission band at 380 nm with a visible PL emission in the green band peaking at 535 nm. The relative intensities of these peaks drastically changed with increased milling time due to the size quantization effect and surface defects (oxygen vacancies and zinc/oxygen interstitials) in the ZnO nanopowder. The Raman spectra of the ZnO powder indicated eight sets of optical phonon modes at the Γ point of the Brillouin zone, which red shifted and broadened with increased milling time. As the milling proceeded, clearly reduced grain size, homogenization, and other properties were observed.
Keywords: ZnO; Nanoparticles; Mechanical milling; Optical property; Microstructure;

The influence of polydimethylsiloxane curing ratio on capillary pressure in microfluidic devices by Ilenia Viola; Antonella Zacheo; Valentina Arima; Antonino S. Aricò; Barbara Cortese; Michele Manca; Anna Zocco; Antonietta Taurino; Ross Rinaldi; Giuseppe Gigli (8032-8039).
► PDMS surface properties as effect of different degree of cross-linking. ► Tailoring PDMS wettability and surface properties to modulate the dynamics of PDMS microdevices. ► Negative capillary pressure induced by a modulation of surface properties. ► Confinement of liquids inside PDMS microchannels.Investigations on surface properties of poly(dimethylsiloxane) (PDMS) are justified by its large application ranges especially as coating polymer in fluidic devices. At a micrometer scale, the liquid dynamics is strongly modified by interactions with a solid surface. A crucial parameter for this process is microchannel wettability that can be tuned by acting on surface chemistry and topography. In literature, a number of multi-step, time and cost consuming chemical and physical procedures are reported. Here we selectively modify both wetting and mechanical properties by a single step treatment. Changes of PDMS surface were investigated by X-ray photoelectron spectroscopy and atomic force microscopy and the effects of interface properties on the liquid displacement inside a microfluidic system were evaluated. The negative capillary pressure obtained tailoring the PDMS wettability is believed to be promising to accurately control sample leakage inside integrated lab-on-chip by acting on the liquid confinement and thus to reduce the sample volume, liquid drying as well as cross-contamination during the operation.
Keywords: PDMS; Wettability; XPS; Microfluidics; Lab-on-chip; Capillary pressure;

Display Omitted► BiFeO3 thin films were prepared on OTS-SAMs by liquid phase self-assembled method. ► Changing the pH value of BFO precursor solutions will affect the phase purity. ► According to the Hard-Soft-Acid-Base principle, Bi3+ has larger deposition rate. ► Pure phase BiFeO3 thin films can be obtained under various pH values. ► Site-selectively deposited micropattern of BiFeO3 film has clear edges.Pure phase BiFeO3 (BFO) thin films were prepared on the ITO/glass substrates covered with functionalized OTS self-assembled monolayers (SAMs) by controllable liquid phase self-assembled method. The hydrophobic surface of OTS-SAMs was changed into hydrophilic surface after UV irradiation, which is helpful to make BFO precursor solutions fully wet the substrate surface. A dense film was formed only on the hydrophilic silnaol group regions, which shows the selectively deposition of BFO precursors. Changing the pH value of BFO precursor solutions will affect the phase purity. The pure phase BFO thin films can be obtained under various pH values, which indicates that the liquid phase self-assembled method is controllable. All pure phase BFO films are dense, smooth, well-grown polycrystalline films, but the size of grains increased gradually along with the increase of pH values. The micropattern of BiFeO3 film has clear edges. The possible growth mechanism of BFO thin films was discussed.
Keywords: Liquid phase self-assembled method; OTS-SAMs; Controllability study; BiFeO3; Thin films; Hard-Soft-Acid-Base principle;

► We report on a dual passivation approach of multicrystalline-silicon (mc-Si). ► The technique combines porous silicon (PS) treatment and sputter-deposition of TiO2:Cr passivation layer. ► The effective minority carrier lifetime was found to be enhanced by more than 2 orders of magnitude (from 2 to ∼733 μs).We report on a dual passivation approach of multicrystalline-silicon (mc-Si), which combines porous silicon (PS) treatment and sputter-deposition of TiO2:Cr passivation layer. At the optimal Cr content of 2 at.%, the effective minority carrier lifetime was found to be enhanced significantly by more than 2 orders of magnitude (from 2 to ∼733 μs). Our results demonstrate that this dual treatment not only provides strong passivation of the mc-Si substrate but decreases also the total surface reflectivity at 500 nm (from 40% for untreated mc-Si samples to ∼19% for TiO2:Cr/PS treated ones).
Keywords: Porous silicon; Cr-doped TiO2; RF-magnetron sputtering; mc-Si passivation; Minority carrier lifetime;

Effect of Ag film thickness on the crystallization mechanism and photoluminescence properties of ZnO/Ag nanoflower arrays by Zhan-Shuo Hu; Fei-Yi Hung; Shoou-Jinn Chang; Bohr-Ran Huang; Bo-Cheng Lin; Wei-Kang Hsieh; Kuan-Jen Chen (8049-8054).
► The various three-dimensional nano structural ZnO have attracted interests and application in the optoelectronics. ► We analyzed the evolution of ZnO nanoflowers in TEM and SEM images. ► The blue emission resulted from the Zn-related defects because of the he phase transition from O-rich to Zn-rich.Three dimensional (3D) zinc oxide (ZnO) nanoflowers have been successfully synthesized on oxidized silver clusters using a vapor transportation method on a 50 nm Ag layer. One dimensional (1D) ZnO nanorods can be fabricated on even the thinner Ag layers (2 nm and 10 nm). During the heating process, with a trace amount of oxygen present, the Ag layer (50 nm) melted and agglomerated forming silver oxide until the temperature reached the melting point of the zinc powder. Initially, the oxygen-rich phase ZnO formed and the zinc atoms diffused from the ZnO shell forming pistils and after an increase in time formed the zinc-rich ZnO nanoflowers. The ultraviolet (UV) emission (3.28 eV) from ZnO nanoflowers and nanorods revealed useful properties relating to the recombination of free excitons and the formation of zinc interstitials or zinc antisites as evidenced by the broad visible peak in the 50 nm Ag layer spectra.
Keywords: Zinc oxide; Silver oxide; Nanoflowers;

Enhancement of photocatalytic activity of TiO2 nanoparticles by coupling Sb2O3 by Dan-Ni Liu; Guo-Hua He; Li Zhu; Wu-Yi Zhou; Yue-Hua Xu (8055-8060).
► The particle size of Sb2O3/TiO2 nanoparticles was in the range of 20–50 nm. ► Sb2O3 doping enhanced the photocatalytic activity of TiO2. ► Sb2O3 was formed on the surface of TiO2, and the Sb―O―Ti bonds were formed. ► The separation of photoinduced electron–hole pairs is an important step.Sb2O3/TiO2 nanoparticles were synthesized by a facile hydrothermal method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transfer infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of Sb2O3/TiO2 nanoparticles were evaluated by the degradation of methyl orange. The results show that the Sb2O3 doping enhanced the photocatalytic activity of TiO2, and the 0.5%Sb2O3/TiO2 nanoparticles show the best photocatalytic activity. The separation of photoinduced electron–hole pairs on the Sb2O3/TiO2 photocatalyst surface is an important step in the photocatalytic reaction because of the Sb2O3 coupling.
Keywords: Photocatalysis; Nanoparticle; Sb2O3-coupling; Sb2O3/TiO2;

► DZ4 superalloy was irradiated by HIPIB. ► The microstructure of alloy in the depth was analyzed by TEM and SEM. ► Polycrystalline nano surface layer was composed of γ phase and carbides. ► The γ′ phase was dissolved in the melted layer that reached about 1.3 μm. ► Dislocation was enhanced due to shock waves over a much deeper depth range.A high intensity pulsed ion beam (HIPIB) was used to irradiate directionally solidified nickel-based superalloy DZ4 with the following parameters: ion content consisting of C n+ (30 at.%) and H+(70 at.%), an accelerating voltage of 250 kV, a pulse duration of 70 ns, a beam current density of 100 A/cm2, irradiation times of 15. As revealed by SEM and TEM, the thermal effect was confined in a ∼1.3 μm thick surface zone, in which rapid melting and cooling occurred. A two-phase nanostructured layer of ∼10 nm thick was formed on the outmost surface. The component phases are the γ phase and the carbide with a particle size of ∼5–10 nm. The presence of dense dislocation networks was observed in depth in the substrate metal, for instance ∼20 μm away from the sample surface, which is caused by shock wave impact.
Keywords: DZ4 superalloy; HIPIB irradiation; Surface nanostructure;

► A new laser process that successfully removes alpha case titanium. ► Experimental ablation rates of alpha case and Ti6Al4V alloy are measured. ► The crack characteristic, roughness and hardness change of alpha case are varied. ► Surface morphology could be used to identify alpha case and measure its thickness. ► An empirical model was proposed for thickness measurement of alpha case layer.Alpha case (an oxygen enriched alloy layer) is commonly formed in forged titanium alloys during the manufacturing process and it reduces the service life of the materials. This layer is normally removed mechanically or chemically. This paper reports the feasibility and characteristics of using a short pulsed laser to remove oxygen-enriched alpha case layer from a titanium alloy (Ti6Al4V) substrate. The material removal rate, i.e., ablation rate, and ablation threshold of the alpha case titanium were experimentally determined, and compared with those for the removal of bulk Ti6Al4V. Surface morphologies of laser processed alpha case titanium layer, especially that of cracks at different ablated depths, were carefully examined, and also compared with those for Ti6Al4V. It has been shown that in the alpha case layer, laser ablation has always resulted in crack formation while for laser ablation of alpha case free Ti6Al4V layers, cracking was not present. In addition, the surface is rougher within the alpha case layer and becomes smoother (R a – 110 nm) once the substrate Ti-alloy is reached. The work has demonstrated that laser is a feasible processing tool for removing alpha case titanium, and could also be used for the rapid detection of the presence of alpha case titanium on Ti6Al4V surfaces in aerospace applications.
Keywords: Ti6Al4V; Alpha case; Ablation rate; Ablation threshold; Morphology; Cracks;

Magnetoelastic coupling in multilayered ferroelectric/ferromagnetic thin films: A quantitative evaluation by A. Chiolerio; M. Quaglio; A. Lamberti; F. Celegato; D. Balma; P. Allia (8072-8077).
► Cost-effective techniques to realize multi-layer multiferroic systems were exploited. ► Two differently engineered PZT nano-crystalline structures were realized. ► Magnetic domain wall motion induced by magnetoelastic coupling was investigated. ► 2-Dimensional statistical properties of enhanced MFM matrices were evaluated. ► Conditions leading to a compromise to realize functional devices were elucidated.The electrical control of magnetization in a thin film, achieved by means of magnetoelastic coupling between a ferroelectric and a ferromagnetic layer represents an attractive way to implement magnetic information storage and processing within logical architectures known as Magnetic Quantum Cellular Automata (MQCA). Such systems have been addressed as multiferroics. We exploited cost-effective techniques to realize multi-layered multiferroic systems, such as sol–gel deposition and RF sputtering, introducing a specific technique to control the crystal structure and film roughness effect on the magnetic domain wall motion and reconfiguration, induced by magnetoelastic coupling, by evaluating the 2-dimensional statistical properties of enhanced MFM matrices. A RF sputtered 50-nm-thick Co layer on a Si/SiO2/Si3N4/Ti/Pt/PbTiO3/Pb(Zr0.53Ti0.47)O3 substrate was realized, exploiting two differently engineered PZT nano-crystalline structures and the conditions leading to a favorable compromise in order to realize functional devices were elucidated.
Keywords: Magnetoelastic coupling; Ferroelectric thin films; Ferromagnetic thin films; PZT;

Photoluminescence of silicon nanostructures prepared via hydrothermal growth progress by Sun Congli; Hu Hao; Yi Liang; Bai Xue; Yang Yumeng; Feng Huanhuan; Xu Jingjing; Chen Yu; Jin Yong; Jiao Zhifeng; Sun Xiaosong (8078-8082).
► SiNSs were synthesized with hydrothermal growth method. ► PL spectra present a PL emission at 400 nm with another weak one at 700 nm. ► The emission centers at the SiNSs’ surface and the confinement effect are responsible for the emissions.This very paper is focusing on the preparation and characterization of silicon nano-structures prepared via hydrothermal growth technology. The morphology and the structure given by the transmission electron microscope indicates that the silicon nanostructures are nano-crystallites, nano-wires and even nano-tubes, all of which are coated with the silica layer. Luminescence performance investigation presents that there is a strong photoluminescence emission at about 400 nm and the weak one at about 700 nm. The controllability over the thickness of the silica coating and the size of silicon nano-core were achieved via the post HF etching procedure or done by prolonging the growth period, respectively. Accordingly, the mechanism of photoluminescence emissions is discussed, which proposes that both the surface radiative recombination center be responsible for 400 nm emission, and so does the confinement effect of the optical phonon for 700 nm. It might, also, come to that the Si―H x bonds on the surface of the exorbitantly HF etched SiNS samples probably gives rise to the 390 nm emission.
Keywords: Hydrothermal growth; Silicon nano-structures(SiNS); Morphology; Luminescence;

Hollow mesoporous titania microsphere with low shell thickness/diameter ratio and high photocatalysis by Jianing Liu; Gaowen Zhang; Wei Ao; Kan Yang; Shaoxian Peng; Christel Müller-Goymann (8083-8089).
Display Omitted► Hollow mesoporous titania microsphere (HTS) was fabricated in a sol–gel process by alternatively coating TiO2 precursor and PDDA onto cationic PS. ► The resultant uniform HTS features a low shell thickness/diameter ratio and a high specific surface area, and thus leads to a high photocatalysis. ► The functional synergy of cationic PS template and cationic polyelectrolyte PDDA layer was underlined. ► We expect that this approach can be extended to the production of other versatile mesoscopic hollow inorganic materials.Hollow mesoporous titania microsphere (HTS) was fabricated in a sol–gel process by alternatively coating of Titania precursor Titanium tetrabutoxide (TBOT) and polydimethyldiallylammonium chloride (PDDA) polyelectrolyte onto cationic polystyrene sphere (PS) template, followed by calcination. Particularly, we underlined the functional synergy of cationic PS template and cationic polyelectrolyte PDDA layer in the formation of HTS. The resultant uniform mesoporous HTS (diameter 1.22 μm) features a low shell thickness/diameter ratio (∼2%) and a high specific surface area (∼77.5 m2/g), and thus leads to a high photocatalysis. We expect that this approach can be extended to the production of other versatile mesoscopic hollow inorganic materials.
Keywords: Hollow mesoporous titania microsphere; Cationic PS template; Cationic polyelectrolyte PDDA; Shell thickness/diameter ratio; Photocatalysis;

Interfacial layer formation at ZnO/CdS interface by Yasuhiro Abe; Arata Komatsu; Hiroshi Nohira; Koji Nakanishi; Takashi Minemoto; Toshiaki Ohta; Hideyuki Takakura (8090-8093).
► We investigate the chemical bonding states at the ZnO/CdS interface. ► We focus on using a combination of XPS and XAFS measurements ► Octahedral ZnO6 species forms in the initial stage of the ZnO deposition ► It is suggested that CdSO4 forms at the ZnO/CdS interface ► We enable the significant investigation by using a combination of XPS and XAFS.We investigated the chemical bonding states at the ZnO/CdS interface by X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) measurements. We found that the octahedral ZnO6 species formed in the initial stage of the ZnO deposition from the Zn L3-edge X-ray absorption near-edge structure spectra. On the other hand, it is difficult to discuss the change of the chemical bonding states of the Zn atoms through the Zn 2p3/2 and the S 2p photoelectron spectra. In addition, we suggested that CdSO4 formed at the ZnO/CdS interface from the analysis of the O 1s photoelectron spectra. We enabled the significant investigation of the chemical bonding states at the ZnO/CdS interface by using a combination of XPS and XAFS measurements.
Keywords: Cu (In,Ga)Se2; CdS; ZnO; XPS; XAFS; XANES; Interface; Local structure; Thin film solar cell;

Ion beam deposition of DLC and nitrogen doped DLC thin films for enhanced haemocompatibility on PTFE by S. Srinivasan; Y. Tang; Y.S. Li; Q. Yang; A. Hirose (8094-8099).
► DLC and DLC:N have been synthesized on PTFE using ion beam deposition. ► Low level of N doping improved mechanical properties and surface smoothness of DLC. ► DLC coating decreased the surface energy and improved the wettability of PTFE. ► Platelets on the DLC and DLC:N were much less aggregated and activated. ► DLC and DLC:N coatings significantly enhanced the haemocompatibility of PTFE.Diamond-like carbon (DLC) and N-doped DLC (DLC:N) thin films have been synthesized on polytetrafluroethylene (PTFE) and silicon wafers using ion beam deposition. Raman spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used to study the structural and morphological properties of the coated surface. The results show that the ion beam deposited DLC thin films exhibit high hardness and Young's modulus, low coefficient of friction and high adhesion to the substrate. Low concentration of nitrogen doping in DLC improves the mechanical properties and reduces the surface roughness. DLC coating decreases the surface energy and improves the wettability of PTFE. The platelet adhesion results show that the haemocompatibility of DLC coated PTFE, especially DLC:N coated PTFE, has been significantly enhanced as compared with uncoated PTFE. SEM observations show that the platelet reaction on the DLC and DLC:N coated PTFE was minimized as the platelets were much less aggregated and activated.
Keywords: Diamond like carbon; Haemocompatibility; PTFE;

► Effect of the substrate temperature on the etch rate and the microstructure of MTJ metals in a CH3OH ICP system. ► Etch rate of CoFe and PtMn increased as the temperature increased. ► CH3OH plasma formed characteristic etching byproducts with metal films. ► Etched surface composition of the etching byproducts changed with increasing temperature. ► Etch rates of magnetic films depended on the substrate temperature.The etching characteristics of the magnetic films (PtMn, CoFe) and hard mask materials (W, Ta) forming a magnetic tunnel junction (MTJ) stack in a CH3OH inductively coupled plasma (ICP) system were investigated. We examined the etch rates of the metal films as a function of substrate temperature, and assessed the microstructures of the etched surfaces using high resolution transmission electron microscopy (HR-TEM). We also analyzed the surface states using X-ray photoelectron spectroscopy (XPS) and TEM electron energy loss spectroscopy (TEM-EELS). The PtMn and CoFe etch rates increased as the temperature increased, whereas the etch rates of W and Ta decreased slightly. Therefore the etch selectivity increased linearly with increasing substrate temperature. The CH3OH plasma formed nonvolatile etching byproducts with the magnetic films and hard mask metals. In the case of PtMn and CoFe, the surface composition of the etching byproducts changed with increasing temperature; the relative concentration of pure metal compared with metal oxide or carbide increased as the substrate temperature rose. The etch rate was determined by the sputtering yield of the materials formed on the etched surface; accordingly the etch rates of those magnetic films would increase due to the higher sputtering yield of pure metal.
Keywords: Magnetic tunnel junction; Dry etching; CH3OH; Surface analysis;

► The effect of the temperature treatment in ethylene glycol on the structure and optical properties of the ZnO films fabricated by SILAR is studied. ► At very high temperatures (>145 °C), PL and XPS data revealed that the rising temperature significantly affects the distribution of defects in the films. ► At low temperatures, a large number of these defects, mostly oxygen defects attributable to Zn(OH)2 in the films, were observed.In this study, ZnO thin films were deposited on glass substrates by the successive ionic layer adsorption and reaction (SILAR) method, and the effect of the temperature treatment in ethylene glycol on the crystal structure, surface morphology, and optical properties of the films were investigated. When the temperature was below 85 °C, the ZnO films showed poor optical transmission and had a rough surface crystal structure. As the temperature was increased, dense polycrystalline films with uniform ZnO grain distribution were obtained. The optical transmittance of the ZnO thin films fabricated at temperatures greater than 95 °C was very high (90%) in the visible-light region. Therefore, it could be concluded that increasing the temperature of treatment in ethylene glycol helps in obtaining fine-grained ZnO films with a high growth rate and a low concentration of oxygen vacancies. However, temperatures greater than 145 °C led to shedding of ZnO from the surface and a reduction in the growth rate. Thus, temperature treatment was confirmed to play an important role in ZnO film deposition instead of post thermal annealing after the film growth.
Keywords: SILAR; Temperature treatment; Ethylene glycol; ZnO thin films;

Electrodeposition of Zn-doped α-nickel hydroxide with flower-like nanostructure for supercapacitors by Zheng You; Kui Shen; Zhicheng Wu; Xiaofeng Wang; Xianghua Kong (8117-8123).
► Zn-doped α-nickel hydroxide with flower-like nanostructures are synthesized by electrochemical deposition method. ► XRD spectra indicate nickel hydroxide doped with Zn is α-Ni(OH)2 with excellent crystallization. ► The formation of Zn-doped Ni(OH)2 include two steps: a honeycomb-like film forms on the substrate first, then flower-like particles forms on the films.Zn-doped α-nickel hydroxide materials with flower-like nanostructures are synthesized by electrochemical deposition method. The samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (SEM) and electrochemical measurements. XRD spectra indicate nickel hydroxide doped with Zn is α-Ni(OH)2 with excellent crystallization. The SEM observation shows that the formation of Zn-doped Ni(OH)2 includes two steps: a honeycomb-like film forms on the substrate first, then flower-like particles forms on the films. The nickel hydroxide doped with 5% Zn can maintain a maximum specific capacitance of 860 F g−1, suggesting its potential application in electrochemical capacitors.
Keywords: Supercapacitors; Nickel hydroxide; Nanostructure;

Magnetic properties and magnetization reversal process of L10 FePt/Fe bilayers magnetic thin films by Liwang Liu; Wei Sheng; Jianmin Bai; Jiangwei Cao; Yuanfu Lou; Ying Wang; Fulin Wei; Jia Lu (8124-8127).
► The magnetization reversal process of the L10 FePt/Fe bilayers was investigated. ► The magnetic interaction of the L10 FePt/Fe bilayers was analyzed. ► The measured coercivities values are optimally fitted by a 1/t Fe 1.15 relation.The L10 FePt (10 nm)/Fe (δ  nm, δ  = 0–15) bilayers were fabricated by using magnetron co-sputtering. The L10 FePt single layer shows good perpendicular orientation and the in-plane hysteresis loop shows almost a linear behavior. When δ is less than 3 nm, the FePt/Fe bilayers show behaviors like one magnetic phase, the coercivities are close to the values determined by Zeeman energy. When δ is larger than 3 nm, the in-plane hysteresis loops show behaviors similar to a soft magnetic film, the coercivities of the bilayers decreases slowly with the increasing Fe thickness because of confining by the exchange length of FePt layer and Fe layer. The measured coercivities values are optimally fitted by a 1/t Fe 1.15 relation. The magnetization reversal process and magnetic interaction were also investigated.
Keywords: FePt; Coercivity; Exchange interaction; Magnetic domain;

Catalytic etching of synthetic diamond crystallites by iron by Tatsuya Ohashi; Wataru Sugimoto; Yoshio Takasu (8128-8133).
Display Omitted► Synthetic diamond crystallites were etched by Fe under H2 (0.2 MPa) at 1173 K. ► The etching behavior of the {1 1 1} was different from {1 0 0} planes of the diamond. ► The etching behavior was also affected by the loading amount of iron. ► Iron carbide-like species may also be formed by the etching of diamond by Fe. ► Raman spectroscopy suggests the diamond structure was retained after the etching.For the expansion of the functionality of diamond crystallites by modification of surface morphology, catalytic etching of synthetic diamond crystallites at 1173 K by iron, which were loaded by the impregnation method using an aqueous solution of iron nitrate; in a streaming mixed gas ( p H 2 = 0.1 MPa , p N 2 = 0.9 MPa ), has been investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The dependence of the crystal planes {1 1 1} and {1 0 0}, of the diamond crystallites and the loading amount of iron on the diamond on the etching behavior by iron particles, the morphology of the etch pits, and potential formation of iron carbide through the catalytic etching, were discussed.
Keywords: Diamond; Synthetic diamond crystallites; Iron; Gasification; Etching; Catalytic etching;

Fabrication of superhydrophobicity on cotton fabric by sol–gel by Yanlong Shi; Yongsheng Wang; Xiaojuan Feng; Guoren Yue; Wu Yang (8134-8138).
► A superhydrophobic cotton fabric was prepared by dip-coating and surface modification. ► Contact angle on this film is about 151̊and the glide angle is less than 20°. ► Surface roughness and low surface energy play crucial role in the formation of superhydrophobicity.A superhydrophobic cotton fabric was prepared by dip-coating TiO2 for four times and subsequent surface modification with n-octadecylthiol (ODT). The surface morphology, crystal structure and chemical composition are studied by SEM, XRD, and XPS, respectively. Water contact angle on the superhydrophobic cotton fabric is approximately 151° and the glide angle is less than 20°. The results show that two factors of higher surface roughness and lower surface free energy play a crucial role for the formation of the superhydrophobicity. Finally, the formation mechanism of superhydrophobicity on the cotton fabric was discussed on the basis of Wenzel's and Cassie's theory.
Keywords: Superhydrophobicity; TiO2; Cotton fabric; ODT;

Adhesive modification of indium–tin-oxide surface for template attachment for deposition of highly ordered nanostructure arrays by W. Gu; L.S. Liao; S.D. Cai; D.Y. Zhou; Z.M. Jin; X.B. Shi; Y.L. Lei (8139-8145).
► Polyvinyl alcohol (PVA) is used to solve the delamination problem of an anodic aluminum oxide (AAO) template on ITO surface. ► PVA has many hydroxyl groups for surface adhesion enhancement and low cost for applications. ► Highly ordered nanorod array on ITO substrate can be electrochemically formed through a well adhered AAO template.Polyvinyl alcohol (PVA), a very cheap polymer with one hydroxyl group in each repeating unit, was spun coated on the surface of an indium–tin-oxide (ITO) substrate to improve the adhesion between the substrate and a nanoporous anodic aluminum oxide (AAO) template layer for a template-directed fabrication of nanostructures. Compared with dihydroxy-terminated polystyrene (PS-dOH) and a silane coupling agent (KH550), PVA was a superior binder because of its abundant hydroxyl groups for adhesion enhancement and its low cost for applications. As an example, a highly ordered CdSe nanorod array free standing on the ITO substrate was electrochemically deposited by using an ultrathin AAO layer as the template on the PVA modified surface. It was demonstrated that the PVA modified ITO can be reliably used for the template-directed fabrication of nanostructures.
Keywords: Ordered nanostructure array; Anodic aluminum oxide; Template deposition; Surface adhesion;

Surface morphology effects on the light-controlled wettability of ZnO nanostructures by V. Khranovskyy; T. Ekblad; R. Yakimova; L. Hultman (8146-8152).
.Display Omitted► As-grown ZnO nanostructures are highly hydrophobic: CA is in range 90–127°. ► UV irradiation of ZnO nanostructures causes the change of their wettability character. ► Contrast and time of wettability change depend on the ZnO surface morphology. ► Both micro- and nano-roughness enhance the current wettability character. ► Complex structures (micro + nano rough) have the most outstanding wettability properties.ZnO nanostructures of diverse morphology with shapes of corrals and cabbages as well as open and filled hexagons and sheaves prepared by APMOCVD technique, are investigated with water contact angle (CA) analysis. The as-grown ZnO nanostructures exhibit pure hydrophobic behavior, which is enhanced with the increase of the nanostructure's surface area. The most hydrophobic structures (CA = 124°) were found to be the complex nanosheaf, containing both the macro-and nanoscale features. It is concluded that the nanoscale roughness contributes significantly to the hydrophobicity increase. The character of wettability was possible to switch from hydrophobic-to-superhydrophilic state upon ultra violet irradiation. Both the rate and amplitude of the contact angle depend on the characteristic size of nanostructure. The observed effect is explained due to the semiconductor properties of zinc oxide enhanced by increased surface chemistry effect in nanostructures.
Keywords: ZnO nanostructures; UV irradiation; Wettability; Hydrophilicity; Hydrophobicity;

► Peptide adsorption on SAMs was investigated by MD simulations. ► Water molecules bound tightly on the zwitterionic sulfobetaine SAM. ► Sulfobetaine SAM exerts a relatively stronger repulsive force on the approaching peptide than hydroxyl-terminated and methyl-terminated SAMs.All-atom molecular dynamics simulations are performed to investigate the neuromedin-B peptide adsorption on the self-assembled monolayers (SAMs) of SH(CH2)10N+(CH3)2CH2CH(OH)CH2SO3 (SBT), SH(CH2)10OH and SH(CH2)10CH3. The force–distance profiles show that the surface resistance to peptide adsorption is mainly generated by the water molecules tightly bound to surfaces via hydrogen bonds (hydration water molecules); but surfaces themselves may also set an energy barrier for the approaching peptide. For the SBT-SAM, the surface first exerts a relatively high repulsive force and then a rather week attractive force on the approaching peptide; meanwhile the hydration water molecules exert a strong repulsive force on the peptide. Therefore, SBT-SAM has an excellent performance on resisting protein adsorption. For the OH-SAM and CH3-SAM, surfaces show low or little energy barrier but strong affinity to the peptide; and the hydration water molecules apply merely a repulsive force within a much narrower range and with lower intensity compared with the case for the SBT-SAM. The analysis of structural and dynamical properties of the peptide, surface and water indicates that possible factors contributing to surface resistance include the hydrogen-bond formation capability of surfaces, mobility of water molecules near surfaces, surface packing density and chain flexibility of SAMs. There are a large number of hydrogen bonds formed between the hydration water molecules and the functional groups of the SBT-SAM, which greatly lowers the mobility of water molecules near the surface. This tightly-bound water layer effectively reduces the direct contact between the surface and the peptide. Furthermore, the SBT-SAM also has a high flexibility and a low surface packing density, which allows water molecules to penetrate into the surface to form tightly-bound networks and therefore reduces the affinity between the peptide and the surface. The results show that the protein-resistant properties of the SAMs are in the decreasing order of SBT-SAM > OH-SAM > CH3-SAM, which provide mechanistic explanation on SBT materials’ excellent anti-fouling performance.
Keywords: Protein adsorption; Molecular dynamics simulation; Molecular simulation; Biomaterial; Anti-fouling; Zwitterionic compound;

► A facile two-step electrochemical route was for the first time used to achieve ZnO nanotube arrays. ► The formation of ZnO nanotube arrays was based on the defect-induced etching mechanism. ► ZnO nanotube arrays exhibited enhanced photocatalytic efficiency due to high oxygen vacancies.A facile two-step electrochemical method was for the first time presented to achieve ZnO nanotube (ZNT) arrays via in situ electrochemically etching electrodeposited ZnO nanorod (ZNR) arrays. The novel two-step synthesis strategy simultaneously considered the recyclability and high surface-to-volume (S/V) ratio of ZNT arrays used as the photocatalyst. Thus, the ZNT photocatalyst in the form of immobilized films was facilely reusable with little loss in degradation of methyl orange (MO). Further investigation on surface nanofeature and surface defect of as-synthesized ZNT arrays indicated that in comparison with the ZNR arrays, the higher photocatalytic activity of the ZNT arrays could not only be ascribed to a larger S/V ratio that allowed more organic substances to adsorbed to the surfaces of the catalyst, but also be related to the larger content of surface oxygen defects as revealed by photoluminescence (PL) spectra that may act as the active centers of the catalysts and capture the photogenerated electrons or holes, decreasing the recombination of the photogenerated electrons and holes. Our synthesis strategy highly paid attention to both the recyclability and biology safety issue that was induced by the discharge of nanoscale materials to natural environment.
Keywords: ZnO nanotube arrays; Electrodeposition; Formation mechanism; Recycling; Photocatalytic activity;

Analysis of the surface state of epi-ready Ge wafers by M. Gabás; S. Palanco; S. Bijani; E. Barrigón; C. Algora; I. Rey-Stolle; I. García; J.R. Ramos-Barrado (8166-8170).
► Ge epi-ready wafers from two different vendors studied using X-ray spectroscopy. ► Oxide layer on all the Ge wafer surfaces formed by GeO and GeO2; layer thickness depending on wafer vendor. ► Probable presence of chlorine at the wafer surfaces. ► Wafer surfaces from one of the vendors contaminated by carbonates.The surface state of Ge epi-ready wafers (such as those used on III–V multijunction solar cells) supplied by two different vendors has been studied using X-ray photoemission spectroscopy. Our experimental results show that the oxide layer on the wafer surface is formed by GeO and GeO2. This oxide layer thickness differs among wafers coming from different suppliers. Besides, several contaminants appear on the wafer surfaces, carbon and probably chlorine being common to every wafer, irrespective of its origin. Wafers from one of the vendors show the presence of carbonates at their surfaces. On such wafers, traces of potassium seem to be present too.
Keywords: Germanium wafers; III–V solar cells; Photoelectron spectroscopy;

Adsorption and dissociation of Cl2 molecule on ZnO nanocluster by Javad Beheshtian; Ali Ahmadi Peyghan; Zargham Bagheri (8171-8176).
► Cl2 Adsorption on Zn12O12 nano-cage has been studied using DFT. ► Cl2 is strongly adsorbed on the cluster via chemisorption or dissociation. ► Gibbs free energy changes are in the range of −0.36 to −0.92 eV at 298 K and 1 atm. ► The processes decrease HOMO/LUMO gap of the cluster and increase the work function. ► The Zn12O12 is transformed to a p-type semiconductor upon the Cl2 dissociation.Adsorption of chlorine molecule (Cl2) on the Zn12O12 nano-cage has been analyzed using density functional theory. It has been shown that the Cl2 molecule is strongly adsorbed on the cluster via two mechanisms including chemisorption and dissociation with Gibbs free energy changes in the range of −0.36 to −0.92 eV at 298 K and 1 atm. These processes also significantly change the electronic properties of cluster by decreasing its HOMO/LUMO energy gap and increasing the work function. The Fermi level shifts towards lower energies upon the interactions between Cl2 and the cluster, resulting in raised potential barrier of the electron emission for the cluster and hence avoiding the field emission. The Zn12O12 cluster is transformed to a p-type semiconductor substance upon the Cl2 dissociation. We believe that the obtained results may be helpful in several fields of study such as sensors, catalysts, and field emission investigations.
Keywords: Zinc oxide nanocluster; Chlorine gas; DFT; Electronic structure;

Insight into CH4 dissociation on NiCu catalyst: A first-principles study by Hongyan Liu; Riguang Zhang; Ruixia Yan; Jingrui Li; Baojun Wang; Kechang Xie (8177-8184).
Display Omitted► C prefers to adsorb on uniform surface of NiCu catalyst. ► The rate-determining step of CH4 dissociation on NiCu is the dissociation of CH. ► Cu-rich surface can resist the carbon deposition in the CH4 dissociation.A density-functional theory method has been conducted to investigate the dissociation of CH4 on NiCu (1 1 1) surface. Two models: uniform surface slab model (Model A) and Cu-rich surface slab model (Model B) have been constructed to represent the NiCu (1 1 1) surface, in which the ratio of Ni/Cu is unit. The obtained results on the two models have been compared with those obtained on pure Ni (1 1 1) and Cu (1 1 1). It is found that the adsorption of CH x (x  = 1–3) on Model B are weaker than on Model A. The rate-determining steps of CH4 dissociation on Model A and B both are the dissociation of CH, and the corresponding activation barriers are 1.37 and 1.63 eV, respectively. Obviously, it is approximately equal on Model A to that on pure Ni (1 1 1) [H. Liu, R. Zhang, R. Yan, B. Wang, K. Xie, Applied Surface Science 257 (2011) 8955], while it is lower by 0.58 eV on Model B compared to that on pure Cu (1 1 1). Therefore, the Cu-rich surface has better carbon-resistance ability than the uniform one. Those results well explain the experimental facts that NiCu/SiO2 has excellent catalytic performance and long-term stability [H.-W. Chen, C.-Y. Wang, C.-H. Yu, L.-T. Tseng, P.-H. Liao, Catalysis Today 97 (2004) 173], however, there is serious carbon deposition on NiCu/MgO–Al2O3 in CO2 reforming of methane [J. Zhang, H. Wang, A. K. Dalai, Journal of Catalysis 249 (2007) 300].
Keywords: NiCu alloy; CH4 dissociation; Reaction barrier; Density functional theory;

Synthesis of HgS nanocrystals in the Lysozyme aqueous solution through biomimetic method by Li Zhang; Guangrui Yang; Guoxu He; Li Wang; Qiaoru Liu; Qiuxia Zhang; Dezhi Qin (8185-8191).
► HgS nanocrystals were prepared in Lysozyme solutions by biomimetic method. ► HgS nanocrystals exhibited good luminescence properties. ► Investigation on interaction of Hg2+/HgS nanocrystals and Lysozyme. ► The change of secondary structure of Lysozyme due to binding to HgS nanocrystals.In the present work, it is reported for Lysozyme-conjugated HgS nanocrystals with tunable sizes prepared at Lysozyme (Lyso) aqueous solutions by using biomimetic method. The obtained HgS nanoparticles with good dispersibility have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission microscopy (HRTEM) and energy-dispersive X-ray spectrum (EDS). The Lysozyme molecules can control nucleation and growth of HgS crystals by binding on the surface of nanocrystals to stabilize protein-capped nanoparticles. Quantum confinement effect of Lyso-conjugated HgS nanocrystals has been confirmed by UV–vis spectra. The nanoparticles exhibit a well-defined emission feature at about 470 nm. Fourier transform infrared (FT-IR) data are used to envisage the binding of nanoparticles with functional groups of Lysozyme. The results of circular dichroism (CD) spectra indicated that the formation of HgS nanocrystals can lead to conformational change of Lysozyme.
Keywords: HgS nanocrystals; Lysozyme; Biomimetic; Quantum effect; Optical properties;

Preparation and photocatalytic activity of Cu-doped ZnO thin films prepared by the sol–gel method by P. Jongnavakit; P. Amornpitoksuk; S. Suwanboon; N. Ndiege (8192-8198).
► Copper can enhance the photocatalytic activity of a ZnO thin film. ► There are two oxidation states of copper present Cu+ and Cu2+ on the surface of the ZnO thin film. ► Cu+ on the surface can react with H2O2 in order to generate the OH radical.Cu-doped ZnO thin films were fabricated on glass substrates by the sol–gel dip-coating method. All samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The grain size and film thickness of the Cu-doped ZnO thin film decreased as a function of the Cu concentrations. All prepared films showed a very high transmittance above 89% in the visible region (400–800 nm). Two oxidation states of Cu in +1 and +2 were identified in the ZnO thin film by X-ray photoelectron spectroscopy (XPS). Their photocatalytic activities were investigated by the degradation of methylene blue (MB) dye under blacklight fluorescent tubes. The film prepared from the Zn2+ solution containing 0.5 mol% of copper ions had the highest photocatalytic activity. The photocatalytic degradation of methylene blue solution as a function of the initial concentrations was evaluated according to the Langmuir–Hinshelwood model. The reaction rate (k) and adsorption equilibrium constant (K) over 1 cm2 of 0.5 mol% Cu-doped ZnO thin film are 15.92 μM h−1 and 0.049 μM−1, respectively.
Keywords: Cu-doped ZnO; Photocatalytic activity; XPS; AFM; Pinning effect;

► We prepared a model anodic film on aluminum substrate in phosphoric acid. ► We successfully filled the whole porous structure with PTFE particles by using an improved sedimentation technique. ► The anodic and composite films were tribologically tested, tracks and counterfaces characterized after tribological tests. ► The incorporation of PTFE particles significantly improves the lifetime of the anodic film.A model anodic film was prepared to incorporate PolyTetraFluoroEthylene (PTFE) nanoparticles into the porous structure of the film. Firstly, the influence of the anodization parameters on the morphology (thickness and pore diameter) was studied, using notably FEG scanning electronic microscopy. Then, using an improved sedimentation technique, the nanoparticles were successfully inserted into the porous structure and onto its surface. EDX and Raman spectroscopy attested the presence of PTFE particles down to the bottom of the pores. Secondly, the study demonstrated the benefit of incorporating the PTFE particles. Tribological tests were also carried out and the lubricating properties of the composite analyzed. Friction coefficient curves showed a 75-fold improvement of the total lifetime of the anodic film with a reduced friction coefficient.
Keywords: Anodized aluminum; PTFE; Lubricating composite; Sedimentation; Friction coefficient; Tribology;

The effect of plasma modification on the sheet resistance of nylon fabrics coated with carbon nanotubes by Wei Zhang; Les Johnson; S. Ravi P. Silva; M.K. Lei (8209-8213).
Display Omitted► Single walled carbon nanotube coated nylon fabrics exhibit electrically conductive behaviour. ► Plasma modified nylon fabrics exhibit sheet resistance of as low as 2.0 kΩ/sq. with respect to 4.9 kΩ/sq. of the untreated fabrics. ► The improvement in electrical conductance is associated with the increases of surface roughness of fibres and the incorporation of oxygen functionalities.Low-pressure oxygen and argon plasmas were used to pre-treat nylon fabrics, and the modified fabrics, together with the raw fabrics, were subsequently coated with single walled carbon nanotubes (SWCNTs) by a dip-drying process. Scanning electron microscopy (SEM) and Raman spectroscopy analyses indicated the attachment of SWCNTs onto nylon fabrics. After the coating with SWCNTs, the plasma modified fabrics exhibited sheet resistance of as low as 2.0 kΩ/sq. with respect to 4.9 kΩ/sq. of the raw fabrics, presumably owing to the increase of fibre surface roughness incurred by the plasma modification, which is evidenced by SEM analyses. Fourier transform infrared spectroscopy (FTIR) analysis indicates the incorporation of oxygen functionalities on fibre surfaces in the plasma modification. This is responsible for the variation of the electrical conductance of SWCNT-coated fabrics with the type of plasma and the duration of plasma ablation.
Keywords: Nylon fabric; Carbon nanotube; Plasma modification; Electronic textile;

X-ray photoelectron, Cu L3MM Auger and X-ray absorption spectroscopic studies of Cu nanoparticles produced in aqueous solutions: The effect of sample preparation techniques by Svetlana Saikova; Sergey Vorobyev; Maxim Likhatski; Alexander Romanchenko; Simon Erenburg; Svetlana Trubina; Yuri Mikhlin (8214-8221).
► Cu nanoparticles were synthesized in aqueous solutions using hydrazine or borohydride. ► Cu(II) oxyhydroxide, cuprite Cu2O and distorted Cu(I) oxide shells were detected above Cu core. ► Particles prepared with ascorbic acid consist of Cu(II) oxyhydroxide overlayer and Cu(I) oxide. ► The core/shell structures depend both on synthetic protocols and ex situ sample handling. ► Precipitation may results in the reduction of oxide layers and enlargement of the particles.Stable sols of copper nanoparticles from 10 nm to 50 nm in diameter synthesized in aqueous solutions using several reducing agents and immobilized on pyrographite were characterized by XPS, Cu L3MM Auger and X-ray absorption spectroscopy (Cu L-edge TEY XANES and Cu K-edge XANES and EXAFS in transmission mode) along with UV–vis spectroscopy, AFM, TEM. It was found that the nanoparticles produced in the hydrazine hydrate and sodium borohydride assisted synthesis are composed of surface Cu(II) oxyhydroxides, and the shells formed by cuprite Cu2O and distorted Cu(I) oxide, which showed the Cu L-edge peak shifted to higher energies, above the metallic core. The relative amount of cuprite was usually larger in the hydrazine systems, but it depended on the sample preparation protocol. The nanoparticles prepared using ascorbic acid as a reactant consisted of rather thick Cu(II) overlayer and largely distorted Cu(I) oxide underneath. The post-synthetic sample handling notably affected the results; in particular, sedimentation (instead of drying of the colloidal solution) favored reduction of the oxide layers to metallic copper and agglomeration of the Cu particles in the precipitate, even in the case of ascorbic acid, while the colloidal particles in the supernatant were oxidized.
Keywords: Copper nanoparticles; Oxidation; XPS; Cu L-edge TEY XANES; Cu K-edge;

Au/CeO2–chitosan composite film for hydrogen peroxide sensing by Wei Zhang; Guoming Xie; Shenfeng Li; Lingsong Lu; Bei Liu (8222-8227).
. A novel composite film consisting of the Au/CeO2–CS has been prepared via a one-step simple hydrothermal reaction. The composite has been designed to construct a mediator-free H2O2 biosensor.Display Omitted► A nanocomposite film consisting of the Au/CeO2–CS has been designed to construct an electrochemical biosensor for hydrogen peroxide assay. ► The GNPs were in situ synthesized on the surface of the CeO2NPs via a simple, environmentally friendly hydrothermal route. ► The resulting sensor presented excellent analytical performance for H2O2. ► Au/CeO2–CS composite film has potential application in the construction of desirable electrochemical biosensing interface.Au nanoparticles (AuNPs) were in situ synthesized at the cerium dioxide nanoparticles (CeO2NPs)–chitosan (CS) composite film by one-step direct chemical reduction, and the resulting Au/CeO2–CS composite were further modified for enzyme immobilization and hydrogen peroxide (H2O2) biosensing. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), UV–vis spectra and electrochemical techniques have been utilized for characterization of the prepared composite. The stepwise assembly process and electrochemical performances of the biosensor were characterized by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and typical amperometric response (it). The Au/CeO2–CS composite exhibited good conductibility and biocompatibility, and the developed biosensor exhibited excellent response to hydrogen peroxide in the linear range of 0.05–2.5 mM (r  = 0.998) with the detection limit of 7 μM (S/N = 3). Moreover, the biosensor presented high affinity ( K m app = 1.93 mM ), good reproducibility and storage stability. All these results demonstrate that the Au/CeO2–CS composite film can provide a promising biointerface for the biosensor designs and other biological applications.
Keywords: CeO2 nanoparticles; Composite film; Horseradish peroxidase; Biosensor;

Wear of UHMWPE against nitrogen-ion-implanted and NbN-coated Co–Cr–Mo alloy formed by plasma immersion ion implantation and deposition for artificial joints by Won-Woong Park; Eun-Kyeom Kim; Jun-Hong Jeon; Jin-Young Choi; Sun-Woo Moon; Sang-Ho Lim; Seung-Hee Han (8228-8233).
► The goal is to reduce the wear of UHMWPE in artificial joints. ► The nitrogen ions were pre-implanted on the surface of Co–Cr–Mo alloy using PIII&D. ► The hard NbN film was subsequently deposited on Co–Cr–Mo alloy using PIII&D. ► The volume wear rate of UHMWPE was reduced up to 48%. ► The life-time of artificial joints could be extended more than twice.NbN thin film was deposited on the Co–Cr–Mo alloy by plasma immersion ion implantation and deposition (PIII&D) to reduce the volume wear rate of UHMWPE. In addition, nitrogen ions were implanted on the surface of the Co–Cr–Mo alloy prior to the NbN film deposition in order to increase the hardness of the substrate. XPS analysis revealed that nitrogen ions were implanted into the surface of the Co–Cr–Mo alloy, leading to the formation of CrN and Cr2N. The UHMWPE volume wear rate was measured using a pin-on-disk tribometer. The wear test result showed that the volume wear rate of UHMWPE against NbN-coated Co–Cr–Mo alloy declined by 20% as compared to that in the untreated Co–Cr–Mo alloy. In addition, the UHMWPE wear rate against the nitrogen-ion-implanted and NbN-coated Co–Cr–Mo alloy could be drastically reduced by up to 48%. It can be concluded that a combination of prior nitrogen ion implantation and NbN coating via PIII&D is a promising surface treatment tool for extending the lifetime of metal-on-polymer artificial joints.
Keywords: Plasma immersion ion implantation and deposition (PIII&D); Artificial joints; Total hip replacement; Pin-on-disk wear test; Niobium nitride (NbN); Nitrogen ion implantation;

► The minimum resistivity of films on drum was 2.7 × 10−3 Ω cm. ► The resistivity of post- annealed films was 5.1 × 10−4 Ω cm. ► The oxygen negative ions dominated films properties at erosion area. ► The active oxygen dominated films properties at non-erosion area.In this paper, ZnO:Al transparent conducting films were prepared on glass substrate by magnetron sputtering from Al doped ZnO ceramic targets. By measuring and analyzing the structure and electrical properties of films in front of targets at different target-to-substrate distance, it was concluded that the bombardment of energetic oxygen negative ions decreased with increasing target-to-substrate distance, dominating variation of resistivity and the microstructure in erosion area, while numbers of active oxygen decrease with increasing target-to-substrate distance, explaining variation of resistivity in non-erosion area. The influence of target-to-substrate distance on electrical and microstructure properties of ZnO:Al films on drum was also investigated in order to confirming our result. The result indicated that both energetic oxygen negative ions and numbers of active oxygen determined the properties of films on drum. While target-to-substrate distance is less than 95 mm, the numbers of energetic oxygen ions are the key factor and vice versa. The optimum resistivity of post-annealed films on drum was 5.1 × 10−4  Ω cm at target-to-substrate distance of 95 mm.
Keywords: AZO films; Target-to-substrate distance; Energetic negative oxygen ions; Numbers of active oxygen;

The antibacterial and hydrophilic properties of silver-doped TiO2 thin films using sol–gel method by Xuemin Wang; Xinggang Hou; Weijiang Luan; Dejun Li; Kun Yao (8241-8246).
► Silver ions were doped during the process of preparing TiO2 sol. ► Doped silver improves antibacterial and hydrophilic abilities of the TiO2 films. ► Suitable doped silver benefits the formation of hydroxyl radicals.Ag–TiO2 composite thin films were deposited on glass slides by sol–gel spin coating technique. The surface structure, chemical components and transmittance spectra were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis spectrophotometer. The TiO2 thin films with silver molar ratio from 0 to 10% were tested for its antibacterial property by using Escherichia coliform (E. coli) under irradiation of UV light. The concentration of E. coli was evaluated by plating technique. The influences of different molar ratio of Ag on hydrophilicity and long-term durability of the films were also investigated by measuring the water contact angle. The results showed that the antibacterial ability was significantly improved by increasing silver content comparing with pure TiO2 thin film, and the best molar ratio of Ag was 5%. While the hydrophilicity of films increased with increasing silver content, and the best molar ratio of Ag was 1%.
Keywords: TiO2 thin film; Sliver; Sol–gel; Bactericidal; Super hydrophilicity;

Surface modification, characterization and adsorptive properties of a coconut activated carbon by Xincheng Lu; Jianchun Jiang; Kang Sun; Xinping Xie; Yiming Hu (8247-8252).
► A coconut activated carbon has been modified using nitric acid. ► Acidic functional groups of oxidized carbons were increased during oxidization process. ► BET surface area and pore volume were decreased. ► The oxidized carbons have higher adsorption capacity of sodium and formaldehyde. ► Chemical properties of activated carbon played an important role in adsorption of metal ions and organic pollutants.A coconut activated carbon was modified using chemical methods. Different concentration of nitric acid oxidation of the conventional sample produced samples with weakly acidic functional groups. The oxidized samples were characterized by scanning electron micrograph, nitrogen absorption–desorption, Fourier transform infra red spectroscopy, Bothem method, pH titration, adsorption capacity of sodium and formaldehyde, and the adsorption mechanism of activated carbons was investigated. The results showed that BET surface area and pore volume of activated carbons were decreased after oxidization process, while acidic functional groups were increased. The surface morphology of oxidized carbons looked clean and eroded which was caused by oxidization of nitric acid. The oxidized carbons showed high adsorption capacity of sodium and formaldehyde, and chemical properties of activated carbon played an important role in adsorption of metal ions and organic pollutants.
Keywords: Activated carbon; Chemical treatment; Surface oxygen complexes; Characterization; Adsorption mechanism;

Display Omitted► A film of packed Al2O3 nanospheres was fabricated on al foils for the first time. ► Superhydrophobicity and low adhesion are obtained on the nanostructures. ► Large-area condensation is restrained on fabricated superhydrophobic surface. ► Spherical condensates grow slightly and can be liquid without ice formation even at −10 °C on the surface.Superhydrophobic alumina films with a 2D close-packed array of nanospheres have been successfully fabricated on industrial aluminum foils by a simple anodization method and following modification. The water contact angle of the resultant surfaces is about 154.6° ± 1.4° and the adhesion of water droplets is very weak. Moreover, spherical droplets grow sparsely on the as-prepared superhydrophobic foils during cooling and can be liquid without ice formation for more than 30 min after being continuously cooled to 0 °C. Such foils have significant application prospects in high-efficient heat exchangers and products operating under low temperature.
Keywords: Aluminum foils; Superhydrophobicity; Nanostructures; Condensation;

► The Ti-Cr-MCM-48 photocatalyst was synthesized by one-step way at room temperature. ► The tetrahedral titanium as dominant state was loaded into mesoporous structures. ► The Ti-Cr-MCM-48 photocatalyst showed high degradation of H2S under visible light.A highly photoactive Ti-containing Cr-modified MCM-48 photocatalyst (Si/Ti = 3.4, Si/Cr = 50) was prepared by a facile one-step method at room temperature. A combination of various physicochemical techniques such as X-ray diffraction (XRD), N2 physisorption, diffuse reflectance UV–vis spectra (DRS) and X-ray photoelectron spectra (XPS) were used to characterize the properties of the synthetic catalysts. The characterization and experimental results indicated that tetrahedral Ti oxide moieties as dominant Ti oxide were loaded into the mesoporous structure and there was a synergistic interaction between the Ti species anchored on the walls and the Cr ions presented in the MCM-48 framework, which was considered to be directly correlated to the photoactivity. The Ti-Cr-MCM-48 sample can remove H2S with the efficiency of 92% under visible light, being the Cr6+ species primarily responsible for this photoactivity. A deactivation was observed as a consequence of sulfate accumulation on the surface of the catalyst and reduction of Cr6+.
Keywords: Ti; Cr; MCM-48; H2S; Photocatalysis; Visible light;

► Friction welding process. ► Joining between Al2O3–yttria stabilized zirconia and 6061 Al alloy. ► Rotational speeds for friction welding were between 630 and 2500 rpm. ► Different thermal data was evaluated for obtaining joint properties and operating conditions. ► Obtained results are useful in modeling the welding process and reliability joint under various conditions.The objective of this work is to establish an analytical data for heat generation by friction welding, based on different parameters of the contact condition between two dissimilar materials. The ceramic composite of Al2O3–YSZ and 6061 Al alloy, which is the example of joining materials by friction welding was used in the experiments. Alumina rods containing 0, 25 and 50 wt% yttria stabilized zirconia were produced by slip casting in Plaster of Paris molds and subsequently sintered at 1600 °C. The diameter of both the ceramic and metal rods was 16 mm. Rotational speeds for friction welding were between 630 and 2500 rpm. As a result, different data was evaluated for obtaining joint properties and operating conditions, and obtained results are useful in modeling the welding process and reliability joint under various conditions.
Keywords: Friction welding; Heat generation; Ceramic matrix composite; Aluminum alloy; Thermal analysis; Interface;

Corrosion behavior of chromium and oxygen plasma-modified magnesium in sulfate solution and simulated body fluid by Ruizhen Xu; Guosong Wu; Xiongbo Yang; Xuming Zhang; Zhengwei Wu; Guangyong Sun; Guangyao Li; Paul K. Chu (8273-8278).
► Cr and O dual ions implantation was used to modify the surface of Mg. ► A Cr-containing oxide layer was formed on the top layer. ► The corrosion resistances of implanted sample were enhanced in both solutions. ► Corrosion product was Mg(OH)2 with different morphologies in two solutions.Because of the unique mechanical properties and biocompatibility, magnesium and its alloys have large potential as lightweight structural materials in the industry in addition to being naturally degradable and resorbable biomaterials. However, their corrosion resistance is usually inadequate especially in an aqueous environment. In this work, pure magnesium is implanted with chromium and oxygen by plasma immersion ion implantation (PIII) and the corrosion behavior is systematically investigated in simulated body fluid and sodium sulfate solution by polarization tests and electrochemical impedance spectroscopy. Our results reveal that chromium and oxygen ion-implanted magnesium have a lower corrosion rate and exhibit less pitting corrosion in the two solutions.
Keywords: Magnesium; Ion implantation; Corrosion resistance;

Investigation of temperature-dependent field emission from single crystal TiO2 nanorods by Jian-Biao Chen; Cheng-Wei Wang; You-Min Kang; Dong-Sheng Li; Wei-Dong Zhu; Feng Zhou (8279-8282).
Display Omitted► Single crystal TiO2 nanorods were synthetized in large scale at 750 °C by CVD. ► Temperature-dependent field emission of TiO2 nanorods is first investigated. ► TiO2 nanorods show high thermal sensitivity in field emission. ► The turn-on field and the current are critically affected by the temperature.Temperature-dependent field emission (FE) of single crystal TiO2 nanorods has been investigated. It is found that the FE properties of TiO2 nanorods are critically affected by environmental temperature of emission tests. As the temperature increases from 290 to 500 K, the turn-on field decreases from 2.16 to 1.76 V/μm, whereas the current density increases. In addition, the physical mechanism of temperature dependence of FE is discussed in detail based on the variation of effective work function, which decreases from 4.3 to 3.64 eV with the temperature rise from 290 to 500 K. It is considered that the reduction of turn-on field and the enhancement of current density are mainly caused by the decrease of effective work function of the emitter.
Keywords: TiO2 nanorods; Field emission; Chemical vapor deposition;

Preparation of magnetic Ni/wollastonite and zeolite P/Ni/wollastonite composite fibers by Jinlong Jiang; Xinyuan Lu; Huan Huang; Chuansong Duanmu; Sumin Zhou; Xu Gu; Jing Chen (8283-8288).
► Core–shell Ni/wollastonite fibers were fabricated by electroless plating. ► Zeolite P/Ni/wollastonite fibers were prepared by in situ hydrothermal method. ► Zeolite P/Ni/wollastonite fibers exhibited good magnetic properties. ► Zeolite P/Ni/wollastonite fibers showed good sorption properties for Cu2+ ions.Magnetic composite fibers with wollastonite (WO) core and Ni shell were prepared by electroless plating using natural mineral WO fibers as supporters. Zeolite P layers were then loaded on the surface of Ni/WO fibers by in situ hydrothermal method. The sample structure and properties were characterized via SEM, XRD, SQUID, EDX, and N2 adsorption. The compact Ni–P coatings on the surface of WO fibers resulted in good magnetic properties of the Ni/WO fibers and zeolite P/Ni/WO fibers. After two crystallization cycles, a continuous zeolite P layer could be formed on the surface of Ni–P coating. The zeolite loading improved the stability of Ni–P coating in the acid solution, resulting in that the zeolite P/Ni/WO fibers can be used at a wide pH range of 3–7. Zeolite P/Ni/WO fiber exhibited a good sorption property for Cu2+ in the aqueous solution (12.48 mg/g) and could be reused after regeneration, indicating that it could be an effective and reusable adsorbent for metal ions from a liquid system.
Keywords: Magnetic material; Zeolite P; Nickel; wollastonite fiber; Electroless plating;

Display Omitted► A DLC/ILs solid–liquid lubricating coatings were fabricated. ► A ground-based simulation facility was employed to carry out the four irradiation experiments. ► Radiations effect the surface composition, structure and morphology of DLC and IL liquid lubricant. ► The tribological properties under high vacuum condition were investigated.In this paper, we fabricated a DLC/ionic liquid (DLC/ILs) solid–liquid lubricating coating and investigated the effect of atomic oxygen (AO), ultraviolet (UV), proton and electron irradiations on composition, structure, morphology and tribological properties of the DLC/ILs solid–liquid lubricating coatings. A ground-based simulation facility was employed to carry out the irradiation experiments. X-ray photoelectron spectroscope (XPS), Raman spectra, and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyzed the structure and composition changes of DLC film and IL lubricant before and after irradiations. The tribological behavior of the DLC/ILs solid–liquid lubricating coating before and after irradiations was investigated by a vacuum tribometer with the pressure of 10−5  Pa. The experimental results revealed that irradiations induced the structural changes, including oxidation, bond break and crosslinking reactions of DLC film and IL lubricant. The damage of proton and AO irradiations to lubricating materials were the most serious, and UV irradiation was the slightest. After irradiations, the friction coefficient of the solid–liquid lubricating coatings decreased (except for AO irradiation), but the disc wear rate increased compared with non-irradiation coatings.
Keywords: DLC/ILs solid–liquid lubricating; Atomic oxygen; Ultraviolet; Proton irradiation; Electron irradiation; Tribological property;

► We investigate the effect of polishing pad on the scratch formation during CMP. ► Both systematic experiment and computational simulation are used. ► The material properties of a pad change during CMP process. ► We first reveal the formation mechanism of pad–particle mixture during CMP. ► Pad–particle mixture is one of the major factors leading to scratch generation.Micro-scratch formation on a post-chemical mechanical polishing (CMP) wafer surface is one of the critical problems that should be solved for miniaturization and reliability of a semiconductor device. In this study, the mechanism of micro-scratch formation during CMP was investigated through experiments and simulations. When a used pad was utilized in the experiments, it was found that micro-scratches could be generated by the polishing process that was done with DI water and additive only without abrasive particles. In order to analyze these micro-scratches under a used pad process, the change in surface properties of the polishing pad before and after the CMP was investigated using various surface sensitive techniques. In addition, 2-dimensional finite element analysis (FEA) of CMP process was performed to verify the experimental results. Especially, the FE model with a particle put inside a pad pore was considered to examine how it plays a role in micro-scratch generation. In summary, the scientific results from experiments and simulations in this study first revealed that the pad–particle mixture could be formed on the pad surface during CMP process, which would be one of the major factors leading to micro-scratch generation.
Keywords: Chemical mechanical polishing (CMP); Finite element analysis (FEA); Surface defects; Micro-scratch;

► It has been investigated the oxidation behaviour of differently pretreated CoNiCrAlY coatings. ► The characteristics of the grown oxide scale influence directly the cooling rate. ► The lowest oxidation rate was exhibited by the EB and vacuum pretreated samples.High velocity oxygen fuel (HVOF) spraying method was used in order to obtain very dense and good adhesive CoNiCrAlY-coatings deposited onto nickel-based alloy. The coatings were differently treated (preoxidized, vacuum treated or electron beam irradiated) before their exposure to cyclic oxidation tests in air at 1000 °C for periods up to 5 h. Changes of the coatings morphology and structure were analysed by scanning electron microscopy (SEM) and X-ray diffraction technique (XRD). The surface temperature of the samples was measured during cooling, between the oxidation cycles, and finally was associated with the thickness of the grown protective oxide scale on the CoNiCrAlY-surface. The experimental results demonstrated that depending on the thickness respectively on the different structures of the grown oxide scale, the cooling rate of the sample surface will be different as well.
Keywords: Cyclic oxidation; CoNiCrAlY coatings; Oxide scale;

First principles study of the adsorption of a NO molecule on N-doped anatase nanoparticles by Juan Liu; Qin Liu; Pengfei Fang; Chunxu Pan; Wei Xiao (8312-8318).
► The adsorption energy at the dangling oxygen site is the highest. ► The adsorption on N-doped particles is stronger than that on the undoped particle. ► There are more active adsorption sites for the N-doped particles. ► The unpaired electron in NO transfers to the empty state of the particle.The adsorption of a NO molecule on 72 atom N-doped TiO2 nanoparticles has been studied by first principles calculations. Two types of adsorption are considered in the calculations. In one type of the adsorption, the NO molecule forms one bond with the particle, while in the other type of adsorption, the NO molecule forms two bonds with the particle. The second type of adsorption is more energetic favorable. The adsorption energies, bond lengths, density of the states (DOSs), and the difference of the charge density are calculated to investigate the adsorption.In the adsorption process, the unpaired electron of the NO molecule transfers to the empty state of the particle, making the Fermi levels lower. As a result, the electrons of the N-doped system occupy lower energy states, making the system energy lower than that of the undoped particle. Since the adsorption of a NO molecule on N-doped nanoparticles is stronger than that on undoped particles, N-doped particles can adsorb more NO molecules on their surfaces than the undoped particles do. Meanwhile, there are more adsorption sites on the N-doped particles, on which the adsorption energies are much higher than that of the undoped particle, some of them are even higher than the highest adsorption energy of the undoped particle. It suggests that N-doped particles are more active and they can adsorb more small toxic gas molecules in the air. So, the doping method can be used to remove NO molecules for the air pollution control through the surface adsorption strategy.
Keywords: N-doped; Anatase; Nanoparticle; Adsorption; First principles calculation; NO;

Erratum to “Oxidative decomposition of volatile organic compounds using thermally-excited activity of hydroxyapatite” [Appl. Surf. Sci. 258 (2012) 5370–5374] by Harumitsu Nishikawa; Takashi Oka; Naoki Asai; Hiroyuki Simomichi; Takashi Shirai; Masayoshi Fuji (8320-8322).