Boosted Charge Transport Efficiency for Bismuth and Oxygen Dual Vacancy-Engineered BiVO₄ Photoanodes

Bismuth vanadate (BiVO 4 ) is a promising photoanode material that has been widely employed to address environmental pollution and the energy crisis. However, defect states substantially affect the efficiency of BiVO 4 photoanodes, and practical applications are severely limited because the fabrication of large-area photoanodes possessing excellent and uniform photoelectrochemical (PEC) activities remains challenging. Herein, bismuth and oxygen dual vacancy-engineered BiVO 4 photoanodes were fabricated by cosputtering BiVO 4 and V targets. The Bi/V atomic ratio of the BiVO 4 photoanode was tailored by tuning the sputtering power of the V target ( P V ), thereby regulating both vacancy types in the BiVO 4 photoanode. The optimized BiVO 4 photoanode was fabricated at a P V of 300 W and featured the highest bismuth vacancy (Bi vac ) concentration (12%) and oxygen vacancy (O vac ) concentration. Under solar spectrum air mass 1.5 irradiation, the current density of the optimized BiVO 4 photoanode was 1.9 mA/cm 2 (at 1.6 V RHE (versus a reversible hydrogen electrode)), which was 11.9 times higher than that of the vacancy-free BiVO 4 photoanode (0.16 mA/cm 2 ). Meanwhile, the optimized dual vacancy-engineered BiVO 4 photoanode exhibited the highest tetracycline hydrochloride degradation efficiency (79%) within 12 min, which was 2.9 times higher than that of the vacancy-free BiVO 4 photoanode (27%). The promoted PEC activity is ascribed to the high carrier concentration and efficient Bi vac - and O vac -derived charge transport. This work offers a strategy for fabricating highly efficient, large-area BiVO 4 photoanodes containing adjustable Bi vac and O vac concentrations.