Boosting charge separation and transfer at the boron-triggered BiVO4 interface for efficient and stable solar water splitting

Abstract

Photoelectrochemical (PEC) water splitting is a promising strategy for solar energy conversion and storage. However, poor charge transfer and sluggish water oxidation reaction restrain the PEC performance. Herein, we propose a simple and effective interface etching strategy on the semiconductor surface to modulate the photoanode/cocatalyst interface, following by the decoration of NiFeBi oxygen evolution catalyst (OEC) for significantly improved oxygen evolution activity and stability of the BiVO4 photoanode. The resultant photoanode achieves a record photocurrent density of 6.33 mA cm−2 at 1.23 VRHE under one sun illumination, over approximately 3.63 times higher than that of the pristine BiVO4. The applied bias photon-to-current efficiency of 2.3% can be attained with showing a good durability of 40 h. Systematic studies have demonstrated that the introduction of electron-deficient state of B accelerates the surface trapping hole and the charge transfer, which enhances the interfacial coupling between BiVO4 and NiFeBi OEC, and strongly drives the hole from the BiVO4 to the NiFeBi surface for capable water oxidation. Density functional theory calculations prove that the surface B treatment increases the effective number of reaction paths of OER and the density of electronic states near the Fermi energy level, which improves the electrical conductivity of the BiVO4/OEC interface. This work provides a feasible strategy for tailoring the interface engineering to significantly enhance the PEC activity and stability of the photoanodes.