Ni3B modified BiVO4 photoanodes for enhanced photoelectrochemical water splitting: The key role of Ni3B on reducing the water oxidation barrier

Bismuth vanadate (BiVO4, BVO) as a promising photoelectrode has been received great attention for photoelectrochemical (PEC) water splitting. However, the slow oxidation kinetics on the surface of BiVO4 limited the PEC water splitting efficiency. Herein, nickel boride (Ni3B, NB) nanoparticles, generally used in electrocatalytic field material, were modified on the surface of BiVO4 photoelectrode as an efficient cocatalyst to accelerate the oxygen evolution reaction. The as-prepared BVO-NB-5P photoelectrode exhibits a remarkable photocurrent density of 1.47 mA·cm−2 at 1.23 V versus the reversible hydrogen electrode (RHE) under air mass (AM) 1.5 G illumination, which is about 2.8 times higher than the bare BiVO4 photoelectrode, and its water splitting rate is 11.3 times higher than bare BiVO4. The PEC studies reveal that the spin coated Ni3B crystal cocatalyst could effectively reduce the water oxidation barrier, and improve the surface charge injection efficiency to 94%, which could boost the photogenerated holes reaction to enhance the PEC performance of BiVO4 photoelectrode.