Understanding the stability of semiconducting photocathodes for solar water splitting

Semiconductor photoelectrochemistry is a powerful means for efficient conversion of solar energy to chemical fuels. Practical implementation of this promising technology has been long challenged by the instability of semiconductor/electrolyte interface. In this Opinion, using III-V semiconductor as an example, recent efforts to advance current understanding of the stability and failure mechanisms for semiconducting pho-tocathodes are summarized. The effects of catalytic kinetics, surface stoichiometry and architectural integrity on both physical and operational stability of photoelectrodes are discussed synergistically. These new insights are useful for exploring and developing durable photoelectrodes of emerging light-absorbers for new applications beyond solar water splitting.