Applied Nanoscience (v.2, #2)

Electrolytes for high-energy lithium batteries by Jennifer L. Schaefer; Yingying Lu; Surya S. Moganty; Praveen Agarwal; N. Jayaprakash; Lynden A. Archer (91-109).
From aqueous liquid electrolytes for lithium–air cells to ionic liquid electrolytes that permit continuous, high-rate cycling of secondary batteries comprising metallic lithium anodes, we show that many of the key impediments to progress in developing next-generation batteries with high specific energies can be overcome with cleaver designs of the electrolyte. When these designs are coupled with as cleverly engineered electrode configurations that control chemical interactions between the electrolyte and electrode or by simple additives-based schemes for manipulating physical contact between the electrolyte and electrode, we further show that rechargeable battery configurations can be facilely designed to achieve desirable safety, energy density and cycling performance.
Keywords: Electrolytes; Lithium ion battery; Ionic liquids; Nanoparticle organic hybrids; Lithium/air; Lithium dendrites

Chemical growth of hexagonal zinc oxide nanorods and their optical properties by Pijus Kanti Samanta; Ashok Kumar Bandyopadhyay (111-117).
A simple wet chemical method has been successfully deployed to fabricate hexagonal zinc oxide nanorods. The structural characteristics were investigated through X-ray diffraction. The crystal unit cell of the nanorods was found to be hexagonal. The morphology of the nanostructures was studied using field emission scanning electron microscopy and transmission electron microscopy. The nanorods are hexagonal in shape. The Zn–O bond formation was confirmed through Fourier transformed infrared spectroscopic analysis. Raman shift measurements revealed various vibrational modes present in the ZnO crystal. The photoluminescence spectrum shows shallow deep level visible emission due to various defect states. Thus, our investigation will be very helpful in the development of ZnO based light emitting/optoelectronic device applications.
Keywords: Zinc oxide; Nanorods; Zn–O bond; Raman-shift; Photoluminescence; Visible-emission; Defect-states

Graphene oxide nanostructures modified multifunctional cotton fabrics by Karthikeyan Krishnamoorthy; Umasuthan Navaneethaiyer; Rajneesh Mohan; Jehee Lee; Sang-Jae Kim (119-126).
Surface modification of cotton fabrics using graphene oxide (GO) nanostructures was reported. Scanning electron microscopic (SEM) investigations revealed that the GO nanostructure was coated onto the cotton fabric. The molecular level interaction between the graphene oxide and the cotton fabric is studied in detail using the Fourier transform infra-red (FTIR) spectra. Thermogravimetric analysis (TGA) showed that GO loaded cotton fabrics have enhanced thermal stability compared to the bare cotton fabrics. The photocatalytic activity of the GO-coated cotton fabrics was investigated by measuring the photoreduction of resazurin (RZ) into resorufin (RF) under UV light irradiation. The antibacterial activity was evaluated against both Gram-negative and Gram-positive bacteria and the results indicated that the GO-coated cotton fabrics are more toxic towards the Gram-positive ones. Our results provide a way to develop graphene oxide-based devices for the biomedical applications for improving health care.
Keywords: Graphene oxide; Antibacterial textiles; Thermogravimetric analysis; Photocatalytic activity; Scanning electron microscope

Magnetic and structural characterization of transition metal co-doped CdS nanoparticles by Sanjeev Kumar; Sunil Kumar; Sanyog Jain; N. K. Verma (127-131).
We report the structural and magnetic properties of the CdS nanoparticles co-doped with Ni and Cu; 3% Ni, Cu co-doped CdS nanoparticles were synthesized by using wet chemical synthesis process. From high-resolution transmission electron microscopy (HR-TEM), it is found that the average diameter of the Ni, Cu co-doped CdS nanoparticles is about 5 nm. X-ray diffraction (XRD) studies show the zinc blende (cubic) structure of Ni, Cu co-doped CdS nanoparticles. Energy dispersive spectroscopy (EDS) confirms the elemental composition of the doped sample. Room temperature magnetic studies are made by the analysis of M-H curves, obtained using superconducting quantum interference device (SQUID). The magnetic behavior has been shown by CdS nanoparticles doped with 3% nickel as well as CdS nanoparticles co-doped with 3% Ni and Cu.
Keywords: Nanoparticles; Dilute magnetic semiconductors; Co-doping; SQUID; Ferromagnetism

A new electrochromic copolymer of 2,2′:5′,2″-terthiophene (TT) with 3,4-ethylenedioxythiophene (EDOT) was synthesized in 0.1 M tetrabutylammonium perchlorate as supporting electrolyte and characterizations of the resulting copolymer P(TT-co-EDOT) performed by cyclic voltammetry, UV–vis spectroscopy, scanning electron microscopy, fourier transform infrared spectroscopy, nuclear magnetic resonance and thermal analysis. Spectroelectrochemical investigations showed that the copolymer film has electrochromic properties. It showed five different colors at various potentials (sky blue, gray, light purple, blues violet and dark blues violet). Double potential step chronoamperometry experiment illustrated that copolymer film had good stability, fast switching time and high optical contrast. At the neutral state of the copolymer λmax was found at 500 nm and Eg was calculated as 1.63 eV. The copolymer film showed a maximum optical contrast of 54% at 1,100 nm with a short response time.
Keywords: Electrochemical polymerization; Conducting polymer; Terthiophene; Ethylenedioxythiophene; Cyclic voltammetry; Electrochromism

Antibacterial potential of biosynthesised silver nanoparticles using Avicennia marina mangrove plant by M. Gnanadesigan; M. Anand; S. Ravikumar; M. Maruthupandy; M. Syed Ali; V. Vijayakumar; A. K. Kumaraguru (143-147).
The present study was aimed to identify the antibacterial potential of biosynthesised silver nanoparticles using different plant parts (leaves, bark and root) of Avicenna marina mangrove plant. Of the selected three different parts, the leaf extract showed the maximum synthesis of silver nanoparticles. The in vitro antibacterial assay (100 μg disk−1 concentration) showed the results of maximum zone of inhibition with the E. coli (18.40 ± 0.97 mm), and minimum (10.87 ± 1.33 mm) zone of inhibition with S. aureus but the concentrations of MIC and MBC values ranged between 6.25 and 50.0 μg ml−1 between the selected bacterial strains. The FTIR results of most potent leaf extract-synthesized silver nanoparticles showed the prominent peaks (620.967; 1,061.02; 1,116.58; 1,187.94; 1,280.50; 1,353.79; 1,384.64; 1,598.50; 1,629.56; 2,854.14 and 2,927.42) in different ranges. Further, the results of XRD analysis showed the 2θ intense values (38.11 and 70.57) within the ranges of Bragg’s reflection. In addition, the AFM analysis showed the results of particle sizes (71–110 nm), particle roughness (11.8 nm), maximum height of the particle roughness (111.8 nm), and average maximum height of the particle roughness (57.5 nm). It can be concluded from the present findings that, the biosynthesis of silver nanoparticles from the leaf extract of A. marina can be used as potential antibacterial agents.
Keywords: Biosynthesis; Antibacterial; Avicennia marina ; Silver nanoparticles

Palladium and Nickel (PdNi) were coated on the manganite nanorods (MN) by a in situ reduction method. The prepared nanocatalyst was characterized by powder X-ray diffractrogram (XRD), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) and electrochemical studies. The XRD patterns and EDS measurements confirm the formation of nanocrystalline PdNi on the surface of the MN. This nanocatalyst was tested for the electrooxidation of methanol in alkaline medium. The PdNi/MN catalyst modified electrode shows improved current response when compared with Pd/MN and Pd/C modified electrodes. The forward oxidation potential was shifted negative and the backward oxidation current was minimized compared with Pd/C. The electrooxidation of methanol was studied at various concentrations of KOH and methanol. The methanol electrooxidation exhibits highest current response for 9 M KOH/6 M CH3OH solution. The presence of MN act as excellent support material and help in the electrocatalytic activity of PdNi.
Keywords: Methanol electrooxidation; Manganese oxide; Palladium; Nickel; Fuel cell

CuS nano/submicro materials with different morphologies were synthesized with spherical, tubular, leaf-like and strip type structures in a simple aqueous system under microwave irradiation and sunlight and employing Cu (CH3COO)2, CuSO4·5H2O, CuCl2, and as copper source and H2NCSNH2, Na2S2O3·5H2O and CH3CSNH2 as sulfur sources. The starting materials were used without assistance of any surfactant or template. An X-ray powder diffraction pattern confirms that the product was CuS with hexagonal phase. Scanning electron microscopy was used to observe the morphologies of the product. Different Phase transitions in CuS with respect to temperature are studied by DSC/TGA. The dependence of morphologies of product on different experimental conditions was also discussed.
Keywords: CuS; Nanomaterial; Self assembly; Morphology; Thermal oxidation; Scanning electron microscopy; X-ray diffraction

Preparation of silver nanoparticles have been carried out using aqueous extract of lemon leaves (Citrus limon) which acts as reducing agent and encapsulating cage for the silver nanoparticles. These silver nanoparticles have been used for durable textile finish on cotton and silk fabrics. Remarkable antifungal activity has been observed in the treated fabrics. The antimicrobial activity of silver nanoparticles derived from lemon leaves showed enhancement in activity due to synergistic effect of silver and essential oil components of lemon leaves. The present investigation shows the extracellular synthesis of highly stable silver nanoparticles by biotransformation using the extract of lemon leaves by controlled reduction of the Ag+ ion to Ag0. Further the silver nanoparticles were used for antifungal treatment of fabrics which was tested by antifungal activity assessment of textile material by Agar diffusion method against Fusarium oxysporum and Alternaria brassicicola. Formation of the metallic nanoparticles was established by FT–IR, UV–Visible spectroscopy, transmission electron microscopy, scanning electron microscopy, atomic force microscopy.
Keywords: Silver nanoparticlesCitrus limon leaves; Antifungal activity; Cotton; Silk

Synthesis and characterization of pure and Co-doped gallium nitride nanocrystals by V. Ganesh; S. Suresh; E. Celasco; K. Baskar (169-176).
Pure and Co-doped gallium nitride (GaN) (5 and 8 mol%) nanocrystals were synthesized by nitridation of Ga–EDTA.NH4 and Co–Ga–EDTA.NH4 complexes. Pure and 5 mol% cobalt-doped GaN did not show any impurity phases in the X-ray diffraction and Raman analysis, whereas 8 mol% Co-doped GaN show secondary phase formation. Transmission electron microscopic study revealed the broad crystal size distribution ranging from 10 to 140 nm. Cathodoluminiscence spectra measured at 20 K shows the suppression of GaN band edge emission with increasing Co concentration. Magnetic measurements of Co-doped GaN revealed a ferromagnetic behavior up to room temperature. The saturation magnetization value increases with increasing impurity phase separation. X-ray photoelectron spectroscopy revealed evidence on the oxidation states of cobalt and excludes the possibility of Co clusters in the doped samples.
Keywords: Semiconductors; Dilute magnetic semiconductors; Nanocrystals; X-ray diffraction; Raman spectroscopy; XPS; TEM; SQUID