Enhancing Photoelectrocatalytic Efficiency of BiVO₄ Photoanodes by Crystal Orientation Control

Bismuth Vanadate (BiVO₄) is a promising photoanode material due to its stability and suitable bandgap, making it effective for visible light absorption. However, its photoelectrocatalytic efficiency is often limited by the poor transport dynamics of photogenerated carriers. Recent research found that varying the atomic arrangement in crystals and Fermi levels across different crystal orientations can lead to significant differences in carrier mobility, charge recombination rates, and overall performance. In this work, we optimized the atomic arrangement by controlling the crystal growth direction to improve carrier separation efficiency using a wet chemical method. Systematic investigations revealed that the preferential [010]-oriented BiVO₄ film exhibits the highest carrier mobility and photocurrent density. Under an applied bias of 1.21 V (vs. RHE) in a 0.5 M Na₂SO₄ electrolyte, it achieved a photocurrent density of 0.2 mA cm^-2 under AM 1.5 G illumination, significantly higher than that of the [121]-oriented (0.056 mA cm^-2) and randomly oriented films (0.11 mA cm^-2). This study provides a deeper understanding of the role of crystal orientation in enhancing photoelectrocatalytic efficiency.