Interfacial repairing of semiconductor-electrocatalyst interfaces for efficient photoelectrochemical water oxidation

Photoelectrochemical (PEC) water splitting is an attractive strategy to convert and store of intermittent solar power into fuel energy. However, the detrimental charge recombination of photogenerated electrons and holes severely limits its efficiency. Despite electrocatalyst loading can obviously improve the PEC conversion efficiency, current systems still suffer from high recombination owing to the surface states. Herein, an interface "repairing" strategy is proposed to suppress the recombination at the semiconductor/electrocatalyst interface. NiO_x layer acts as an interfacial repairing layer to efficiently extract photogenerated charge carriers and eliminate the surface states via high hole-transfer kinetics rather than as a traditional electrocatalyst. As expected, the resulting repaired system yields an impressive photocurrent density of 4.58 mA cm^-2 at 1.23 V (vs. RHE), corresponding to a more than three-fold increase compared to BiVO₄ (1.40 mA cm^-2). Our work offers an appealing maneuver to improve the water oxidation performance for the semiconductor/electrocatalyst coupling system.