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 (O_V) 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 O_V into photoanodes, achieving enhanced charge transport and accelerated water oxidation kinetics.