Crystal Orientation Points The Way To Improved Hydrogen Production

During my degree I always loved learning about crystallography, as it's a field where simple geometry on a microscopic scale can have big, visible effects. A classic example is the salt crystal pictured below – in sodium chloride the ions adopt a cubic arrangement, and this stays rigidly fixed even if you have the unimaginably huge number of ions it takes to be visible. As a result, single crystals of salt are cube-shaped no matter how big they are. This can result in widely varying properties in different directions, all depending on the geometry of those microscopic cubes of ions.

A team of researchers, including some from the University of Cambridge, have reported improved performance of a photocathode based on exactly that kind of variation (the original paper is here). Photocathodes convert incident light into an electric current, and they're of interest because they may one day allow the large-scale conversion of sunlight into fuels like hydrogen. That