Achieving the world's highest efficiency in hydrogen production by water electrolysis

Kazuhiro Sayama and Rie Saitou, Solar Light Energy Conversion Group, the Energy Technology Research Institute of the National Institute of Advanced Industrial Science and Technology (AIST), have developed a very high-performance multilayered photoelectrode for hydrogen production by water electrolysis using an oxide semiconductor photoelectrode. In the reaction to convert solar energy into hydrogen energy, a solar energy conversion efficiency of 1.35 % has been achieved in a carbonate electrolyte by stacking two photoelectrodes. This value is about twice the reported conversion efficiency of oxide photoelectrodes. Using solar energy, the developed technology can substantially reduce the electrolysis voltage required for hydrogen production by water electrolysis. The technology is expected to realize low-cost hydrogen production.