Structured BiVO₄Photoanode Fabricated via Sputtering for Large Areas and Enhanced Photoelectrochemical Performance

Bismuth vanadate (BiVO4) is a promising photoanode material; however, its efficiency significantly changes depending on the atomic ratio of Bi/V, and there is no suitable method for synthesizing large-area photoanodes. In this study, an efficient BiVO4 photoanode was fabricated via sputtering, by manipulating the molar ratio of Bi/V with V solution annealing. V solution annealing not only adjusted the atomic ratio of Bi/V but also increased the number of O vacancies, thereby improving the charge-separation and charge-transport efficiencies. Consequently, the photocurrent density of the sputtered photoanode with V solution annealing (BVO-V) was 1.86 mA/cm2, which is 23 times higher than that of the sputtered photoanode annealed under air conditions (BVO-A, 81.0 μA/cm2). Furthermore, microcone-patterned fluorine-doped SnO2 was fabricated to increase the active area and reduce the high reflectance, owing to the dense deposition because of the sputtering. Thus, the photocurrent density of the MC-BVO was 3.11 mA/cm2, which is approximately 67% higher than that of BVO-V (1.86 mA/cm2).