Interface-Confined Surface Engineering via Photoelectrochemical Etching toward Solar Neutral Water Splitting

Photogenerated electron-hole recombination arising from the interface/surface among semiconductor/cocatalyst/electrolyte becomes prominent for photoelectrochemical (PEC) water splitting, which principally retards the charge transfer pathways and reduces the oxygen reaction kinetics, especially in a neutral environment. Herein, interface-confined surface engineering via a PEC reduction strategy was carried out on a semiconductor/transition metal oxide system in a neutral electrolyte, which can remove the interfacial charge recombination and mediate the charge transfer pathways, and importantly stabilize the semiconductor for a long-term operation. Surface-confined CoMoO4-x/BiVO4 exhibits a current density of 3.5 mA cm(-2) at 1.23 V-RHE under 1 sun irradiation with an excellent stability for 20 h in 0.5 M Na2SO4, showing one of the best photocorrosion resistance performances among BiVO4 photoelectrodes under near-neutral pH conditions. A comparable PEC activity and stability were achieved using pristine BVO, CoOx/BiVO4, and MoOx/BiVO4 with the PEC etching, which clarify the mechanism of the reduced barrier layer and the defected CoMoO4-x catalysts in boosting the charge transfer efficiency and stabilizing BiVO4. Meanwhile, CoOx acts as a promoter enhancing PEC activity and MoOx acts as a passivation layer protecting the semiconductor from photocorrosion. This work sheds light on that the interface-confined surface modification plays an essential role in modulating the charge transfer pathways, especially for a reaction occurring on a surface, which may lead to a new direction of using a neutral environment for high-performance photoelectrode design toward achieving efficient solar energy conversion.

Automated summary

This study demonstrates the importance of interface-confined surface modification in modulating charge transfer pathways for efficient solar energy conversion. By using a PEC reduction strategy, the interface-confined CoMoO4-x/BiVO4 system exhibits excellent photocorrosion resistance and long-term stability, showing potential for high-performance photoelectrode design in a neutral environment.