Modification of the BiVO4 photoelectrode surface with Ni-doped vanadium borate for improved charge transfer and photoelectrochemical water splitting

Abstract

The poor oxygen evolution kinetics on the surface of BiVO₄ have severely limited the industrialization of BiVO₄ photoelectrodes. In this work, we report a bimetallic trace Ni-doped vanadium borate (Ni-VB) modification of the BiVO₄ photoelectrode surface (Ni-VB/BiVO₄) using the photo-electrodeposition method for photoelectrochemical (PEC) water splitting. The Ni-VB/BiVO₄ photoelectrode exhibited an excellent photocurrent density that reached 4.8 mA cm⁻² at 1.23 V (vs. reversible hydrogen electrode, RHE) under AM 1.5 G illumination, which is four times higher than that of the pristine BiVO₄ photoelectrode, and the charge injection efficiency of Ni-VB/BiVO₄ reached 94.5%. Meanwhile, the Ni-VB/BiVO₄ photoelectrode remained stable at a bias voltage of 0.8 V (vs. RHE) for ten hours. Density functional theory (DFT) calculations for the oxygen evolution reaction (OER) in this work demonstrate that the Ni-VB on the surface of the BiVO₄ photoelectrode promotes interfacial charge transfer and accelerates the oxygen evolution kinetics, resulting in excellent PEC performance for water splitting.