NiMoOx as a highly protective layer against photocorrosion for solar seawater splitting

Abstract

Photoelectrochemical (PEC) seawater splitting is a promising alternative for solar energy conversion and storage. However, the sluggish surface reaction dynamics and photocorrosion/corrosion generally limit the semiconductors for potential large-scale application. In this study, an ultra-protected NiMoO_x layer was constructed and decorated on the BiVO₄ photoanodes without any complex procedure for PEC seawater splitting. The NiMoO_x/BiVO₄ photoanode shows a photocurrent density of 3.30 mA cm⁻² at 1.23 V_RHE in simulated seawater under one sun AM 1.5G irradiation. The comparable NiO_x and MoO_x layer was also assembled on BiVO₄. NiO_x plays the role of enhanced PEC activity of BiVO₄, and MoO_x acts to strongly protect the photoanode from corrosion. Collaborated with the elemental analysis of the surface, part of Ni leaches out from the NiMoO_x layer, boosting the passivation of Mo during long-term operation and inhibiting the photoanodes from photocorrosion/corrosion in a seawater medium. NiMoO_x/BiVO₄ reaches an excellent stability over 190 h in natural seawater, with a photocurrent density of 3.0 mA cm⁻² at 1.23 V_RHE, representing the best photocorrosion resistance for semiconductors in a seawater PEC cell. This study provides an ultra-stable layer for protecting semiconductors against seawater photocorrosion/corrosion for solar water splitting.