Enhanced BiVO4 Photoanode Photoelectrochemical Performance via Borate Treatment and a NiFeOx Cocatalyst

To settle the slow water oxidation kinetics and charge recombination of BiVO4 photoanodes, boron-treated BiVO4 combined with a NiFeOx electrocatalyst (NiFeOx/B/BiVO4) electrode is prepared. The resultant NiFeOx/B/BiVO4 demonstrates a 5.22 mA/cm2 current density at 1.23 V vs RHE under AM 1.5 G illumination without any sacrificial agent. Significantly, the applied bias photon-to-current efficiency of the NiFeOx/B/BiVO4 photoanode reaches 1.96% at 0.7 V vs RHE, which is much higher than that of pristine BiVO4. Such excellent performance can be attributed to the existence of self-adsorbed [B(OH)4]− ligands and NiFeOx electrocatalysts, enhancing the separation of photoelectron–hole pairs. This work provides a way to construct effective photocatalysts for solar water splitting.