Enhancing the photoelectrochemical performance of BiOI-derived BiVO4 films by controlled-intensity current electrodeposition.

This study investigates the fabrication of BiVO₄ photoanodes using a controlled-intensity current electrodeposition method to improve their photoelectrochemical (PEC) performance. The impact of varying the deposition current density and VO(acac)₂ concentration was systematically analyzed to optimize the crystallinity, surface morphology, and electronic properties of the films. Subsequently, an electrochemical deposition method was developed to facilitate the uniform distribution of V₂O₅ among Bi-O-I flakes to homogeneously enhance the conversion reaction. The XRD pattern confirms the monoclinic scheelite BiVO₄ structure with dominant (121) and (004) peaks. FESEM imaging revealed that the different deposition conditions influenced the surface morphologies of the BiOI and BiVO₄ films. Photocurrent density measurements showed that BiVO₄(326) achieved 1.2 mA·cm^-2 at 1.23 V vs RHE, representing a significant enhancement compared to the other samples. The surface hole injection efficiency was measured to be 47%, whereas the incident photon-to-current efficiency reached a peak of 18.1% at 420 nm. The applied bias photon-to-current efficiency of BiVO₄(326) was also superior to that of the samples fabricated with lower current density, highlighting the benefits of the optimized electrodeposition conditions for the former.