Boosted Charge Transport Efficiency for Bismuth and\nOxygen Dual Vacancy-Engineered BiVO<sub>4</sub> Photoanodes

Bismuth\nvanadate (BiVO<sub>4</sub>) is a promising photoanode material\nthat has been widely employed to address environmental pollution and\nthe energy crisis. However, defect states substantially affect the\nefficiency of BiVO<sub>4</sub> photoanodes, and practical applications\nare severely limited because the fabrication of large-area photoanodes\npossessing excellent and uniform photoelectrochemical (PEC) activities\nremains challenging. Herein, bismuth and oxygen dual vacancy-engineered\nBiVO<sub>4</sub> photoanodes were fabricated by cosputtering BiVO<sub>4</sub> and V targets. The Bi/V atomic ratio of the BiVO<sub>4</sub> photoanode was tailored by tuning the sputtering power of the V\ntarget (<i>P</i><sub>V</sub>), thereby regulating both vacancy\ntypes in the BiVO<sub>4</sub> photoanode. The optimized BiVO<sub>4</sub> photoanode was fabricated at a <i>P</i><sub>V</sub> of\n300 W and featured the highest bismuth vacancy (Bi<sub>vac</sub>)\nconcentration (12%) and oxygen vacancy (O<sub>vac</sub>) concentration.\nUnder solar spectrum air mass 1.5 irradiation, the current density\nof the optimized BiVO<sub>4</sub> photoanode was 1.9 mA/cm<sup>2</sup> (at 1.6 V<sub>RHE</sub> (versus a reversible hydrogen electrode)),\nwhich was 11.9 times higher than that of the vacancy-free BiVO<sub>4</sub> photoanode (0.16 mA/cm<sup>2</sup>). Meanwhile, the optimized\ndual vacancy-engineered BiVO<sub>4</sub> photoanode exhibited the\nhighest tetracycline hydrochloride degradation efficiency (79%) within\n12 min, which was 2.9 times higher than that of the vacancy-free BiVO<sub>4</sub> photoanode (27%). The promoted PEC activity is ascribed to\nthe high carrier concentration and efficient Bi<sub>vac</sub>- and\nO<sub>vac</sub>-derived charge transport. This work offers a strategy\nfor fabricating highly efficient, large-area BiVO<sub>4</sub> photoanodes\ncontaining adjustable Bi<sub>vac</sub> and O<sub>vac</sub> concentrations.