Claims of burning water abound these days, but a shot in the arm for solar power could come from the discovery of a titanium silicide semiconductor that acts not only as a catalyst for splitting water but does its own gas separation step too. Martin Demuth and colleagues at the Max Planck Institutes for Bioinorganic Chemistry and for Coal Research, in Germany, spotted the very unusual properties of titanium silicide, which they say make it ideal for exploiting sunlight to produce hydrogen. One of the problems of hankering after the so-called "hydrogen economy" has always been that hydrogen is not so much a fuel as an energy transfer agent. This new technology could at last make producing the energy transfer agent efficient.