Maneuvering cuprous oxide-based photocathodes for solar-to-fuel conversion

Cuprous oxide (Cu2O)-based photocathodes have been attracting enduring interest for green and sustainable solar fuel production by solar-driven photoelectrochemical (PEC) water splitting and CO2 reduction reactions. Although Cu2O is featured by the theoretically outstanding photoactivity owing to the favorable band-gap and appropriate band alignment, wide-spread utilization of Cu2O is largely hampered by its severe photo-corrosion and difficulty in charge transfer/separation modulation, hence rendering fabricating robust, stable and high-efficiency Cu2O-based photoelectrodes a continuously challenging issue. In this review, fundamentals of PEC reactions including water splitting and CO2 reduction are concisely elucidated, and then diverse strategies for constructing a large variety of quintessential Cu2O-based photocathodes are comprehensively summarized. Subsequently, predominant Cu2O-based photocathodes currently being extensively explored in PEC water splitting and CO2 reduction reactions are specifically introduced. Finally, future perspective and outlook of Cu2O-based photocathodes in these two booming research fields are forecasted. Our review could provide enriched information on rational design and utilization of Cu2O-based photocathodes for solar fuel production.