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.