NEDO’s Artificial Photosynthetic Chemistry Process Technology Research Association (ARPChem) has developed a two-stage cell in tandem arrangement comprising a hydrogen-generating photocatalyst made up from Cu, In, Ga and Se (CIGS) and an oxygen-generating photocatalyst (BiVO4). CIGS is a p-type semiconductor, and by forming an n-type semiconductor on its surface, electrons and holes are generated in the CIGS by light irradiation which can be efficiently separated and recombined with high quantum efficiency. The device could be used to generate hydrogen at 12.5 % energy conversion efficiency.

NEDO news release, August 27, 2018