Semiconductor-based Photocatalytic Hydrogen Generation

A significant process has been achieved on semiconductor-based photocatalytic hydrogen generation through water splitting. The processes in the photocatalytic generation of hydrogen include light absorption of the semiconductor photocatalyst, generation of excited charges (electrons and holes), recombination of the excited charges, separation of excited charges, migration of the charges, trap of excited charges, and transfer of excited charges to water or other molecules. The total amount of hydrogen generated is mainly determined by the amount of excited electrons in the water/photocatalyst interface in reducing water. The reaction of photogenerated H2and O2 to form H2O on the photocatalyst surface is normally called 'surface backreaction (SBR)'. The separation of the photoactive sites necessary for hydrogen and oxygen evolution, and which is always accompanied by the surface separation of the photogenerated electrons and holes, has been shown to be greatly affected by the surface properties of the photocatalysts.