Comparative Studies on Synthesis Methods of BiVO₄ for Photoelectrochemical Applications

In this work, we report optical and photoelectrochemical properties of BiVO₄ synthesized by microwave, sonochemical, sol-gel, and direct deposition on conductive substrate methods. Structural and morphological characterization using XRD, SEM, and AFM confirmed the presence of both monoclinic and tetragonal phases, with variations in particle size and surface roughness. UV-Vis spectroscopy revealed band gaps in the range of 2.38-2.51 eV. Photoelectrochemical performance was evaluated through measurements of photocurrents under varying illumination wavelengths and applied potentials. BiVO₄ as a thin film exhibited the highest photocurrent intensity due to its superior semiconductor-substrate contact. In contrast, BiVO₄ samples obtained as a powder showed significantly lower photocurrents but demonstrated the photocurrent switching effects, attributed to the presence of surface trap states and oxygen vacancies. The obtained results highlight the importance of synthesis strategy in tailoring BiVO₄ properties for use as a photoelectrochemical cell and suggest potential applications in molecular electronics, such as logic gates and memory devices.