Nano-bismuth vanadate supported on fibrous silica reduces the intrinsic charge impedance for superior photoelectrochemical water-splitting performance†

Abstract

Bismuth vanadate (BiVO₄) is one of the top-notch materials used in photoelectrochemical (PEC) water-splitting studies owing to its promising properties. However, its practical application is significantly hindered by its inherent limitations, which reduce its efficiency in water-splitting processes. In this study, a novel approach involving size transformation and improved dispersion of BiVO₄ was achieved via a microemulsion method, with fibrous silica serving as a support matrix. The fabricated catalyst, fibrous silica bismuth vanadate (FSBVO), was comprehensively characterized using XRD, FTIR, FESEM, TEM, UV-Vis/DRS, Mott–Schottky analysis, EIS, and PL spectroscopy and compared with commercial BiVO₄. The PEC analysis demonstrated that the FSBVO photoanode delivered a remarkable performance, attaining a photocurrent density of 19.8 mA cm⁻² at 1.23 V_RHE and a solar-to-hydrogen conversion efficiency of 24.35%, which correspond to enhancements of approximately 27.5 and 27.4 times, respectively, compared with those obtained using the pristine BiVO₄ photoanode. Further in-depth studies revealed that the improvement in the PEC water-splitting performance was mainly attributed to the transformation of BiVO₄ into nanoparticles and the distinctive Si–Bi interaction, which increased the carrier density and facilitated efficient electron transport, thereby accelerating the oxygen evolution kinetics. This study highlights the potential of FSBVO photoanodes and provides valuable insights for designing advanced materials to enhance the PEC water-splitting efficiency.