Cuprous oxide photocathodes for solar water splitting

Solar water splitting is a promising technique for harvesting solar energy and converting abundant sunlight into storable hydrogen fuel. The cuprous oxide photocathode, one of the best-performing photocathodes, possesses theoretical photocurrent density up to 14.7 mA cm ?2 photovoltage as large 1.6 V, making it possible convert in low-cost way. Herein, comprehensive review improving performance photocathode presented with focus on crucial issues increasing density, photovoltage, durability from aspects solving incompatibility between electron diffusion length optical absorption distances, interfacial band alignment, revealing impact deficiencies, introducing protective overlayers. We also outline development unassisted tandem devices component, emphasizing critical strategies enhance transmittance laying solid foundation further boost conversion efficiency. Finally, perspective regarding future directions optimizing boosting efficiency unbiased device presented.