High-Performing BiVO4 Thin Films for Photoassisted Water Oxidation: A Scalable Ultrasonic Spray Pyrolysis Approach

In this study, we report the scalable preparation of uniform BiVO₄ thin films using ultrasonic spray pyrolysis (USP) for photoelectrochemical water-splitting applications. We systematically optimized deposition parameters, such as nozzle traverse step width, the number of deposition cycles, and substrate temperature, to achieve films with excellent uniformity and precisely controlled thickness. Additionally, through the optimization of precursor molar ratio (R_V/Bi) and subsequent removal of excess V₂O₅, the porosity in bulk BiVO₄ could be ingeniously adjusted. The optimized BiVO₄ thin films with an R_V/Bi ratio of 2.5:1 achieved a remarkable photocurrent density of 1.66 mA/cm² at 1.23 V vs RHE, which aligns competitively with the state-of-the-art achievement reported in the literature for pristine BiVO₄ thin films. The study demonstrates that USP is a promising approach for producing high-performance and high-quality BiVO₄ thin films for PEC applications.