The effect of composite catalyst on Cu2O/TiO2 heterojunction photocathodes for efficient water splitting

Cuprous oxide is a highly efficient p-type semiconductor, which has high absorption efficiency in the visible region, making it ideal for the use as a photocathode material for hydrogen evolution reaction. However, the theoretical efficiency of cuprous oxide is still unachievable in practical situations, due to the severe photocorrosion and the high recombination rate of photogenerated electron-hole pairs. In this work, ultra-thin TiO2 deposited via atomic layer deposition (ALD) was used as a protection layer, and rGO/NiFe-LDH was loaded as a catalyst decoration on Cu2O photocathode. The protection layer led to suppression of photocorrosion of Cu2O, and the catalyst promoted chemical reaction kinetics. The photo-generated current density reached −3.71 mA/cm2, and the photoelectric conversion efficiency reached 0.41%. The effect of catalyst on the built-in electric field of photocathode and the transport mechanism of carrier were also investigated in detail. This work hereby provides a new idea of the application of Cu2O in the domain of photoelectrochemical (PEC) water splitting.