Structured BiVO<sub>4</sub> Photoanode Fabricated via Sputtering for Large Areas and Enhanced Photoelectrochemical Performance
Sucheol Ju, Junho Jun, Soomin Son, Jae‐Min Park, Hangyu Lim, Wonjoong Kim, Dongwoo Chae, Heon Lee
Abstract
Bismuth vanadate (BiVO 4 ) 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 BiVO 4 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/cm 2, which is 23 times higher than that of the sputtered photoanode annealed under air conditions (BVO-A, 81.0 μA/cm 2 ). Furthermore, microcone-patterned fluorine-doped SnO 2 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/cm 2, which is approximately 67% higher than that of BVO-V (1.86 mA/cm 2 ).