Boron-Doped Silicon Diatom Frustules as a Photocathode for Water Splitting

An effective solar-powered silicon device for hydrogen production from water splitting is a priority in light of diminishing fossil fuel vectors. There is increasing demand for nanostructuring in silicon to improve its antireflective properties for efficient solar energy conversion. Diatom frustules are naturally occurring biosilica nanostructures formed by biomineralizing microalgae. Here, we demonstrate magnesiothermic conversion of boron-doped silica diatom frustules from Aulacoseira sp. into nanostructured silicon with retention of the original shape. Hydrogen production was achieved for boron-doped silicon diatom frustules coated with indium phosphide nanocrystal layers and an iron sulfur carbonyl electrocatalyst.