Suppressing photoinduced charge recombination at the BiVO4∥NiOOH junction by sandwiching an oxygen vacancy layer for efficient photoelectrochemical water oxidation

Nickel oxyhydroxide (NiOOH) is regarded as one of the promising cocatalysts to enhance the catalytic performance of photoanodes but suffers from serious interfacial charge-carrier recombination at the photoanode parallel to NiOOH interface. In this work, surface-engineered BiVO4 photoanodes are fabricated by sandwiching an oxygen vacancy (O-vac) interlayer between BiVO4 and NiOOH. The surface O-vac interlayer is introduced on BiVO4 by a chemical reduction treatment using a mild reducing agent, sodium hypophosphite. The induced O-vac can alleviate the interfacial charge-carrier recombination at the BiVO4 parallel to NiOOH junction, resulting in efficient charge separation and transfer efficiencies, while an outer NiOOH layer is coated to prevent the O-vac layer from degradation. As a result, the as-prepared NiOOH-P-BiVO4 photoanode exhibits a high photocurrent density of 3.2 mA cm(-2) at 1.23 V vs. RHE under the irradiation of 100 mW/cm(2) AM 1.5G simulated sunlight, in comparison to those of bare BiVO4, P-BiVO4, and NiOOH-BiVO4 photoanodes (1.1, 2.1 and 2.3 mA cm(-2), respectively). In addition to the superior photoactivity, the 5-h amperometric measurements illustrate improved stability of the surface-engineered NiOOH-P-BiVO4 photoanode. Our work showcases the feasibility of combining cocatalysts with O-vac, for improved photoactivity and stability of photoelectrodes. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Introducing an oxygen vacancy interlayer between BiVO4 and NiOOH can enhance the photocurrent density and stability of the photoanode.