Plasma Treatment Induced Oxygen Vacancies and N Doping in the BiVO4 Photoanode toward Improved Charge Transfer and Facilitated Water Oxidation

BiVO4 is a promising material candidate for photoelectrochemical (PEC) water splitting. However, the BiVO4 photoanode commonly suffers from poor charge carrier transport and sluggish water oxidation kinetics, which limits its PEC performance. Nitrogen (N) doping has been proven as an effective approach to improve electric conductivity and accelerate the water oxidation kinetics of the BiVO4 photoanode. Nevertheless, a simple and mild method for introducing a N dopant into BiVO4 remains lacking. Herein, N2 plasma treatment is employed as a post-treatment method to achieve effective N doping and induce oxygen vacancies (OV) in BiVO4 photoanodes. This treatment significantly improves the charge transfer and accelerates the kinetics of water oxidation. The photocurrent density of the N2-plasma-treated BiVO4 photoanode reaches 1.39 mA cm–2 at 1.23 V versus the reversible hydrogen electrode (RHE), which surpasses that of pristine BiVO4 (0.30 mA cm–2) by a substantial margin. This work provides a facile room-temperature N2 plasma approach for the simultaneous introduction of N doping and OV into photoanodes, achieving enhanced charge transport and accelerated water oxidation kinetics.