Tailoring morphology-controlled bismuth vanadate composite with graphitic carbon nitride for photocatalytic H2 evolution

Hydrogen energy serves as a significant and environmentally benign energy source. Photocatalytic water splitting, an exemplary alternative and eco-friendly process, is advantageous as it operates at lower temperatures and requires less energy. Investigations into the role of bismuth vanadate morphology—specifically non-uniform shapes (NS-BV), polyhedron (PD-BV), and nanoflakes (NF-BV)—alongside graphitic carbon nitride (GCN) revealed significant influences on hydrogen production through visible light-driven water splitting. The NF-BV/GCN catalyst demonstrated a remarkable hydrogen production rate of 86.62 μmol/g.h, surpassing the NS-BV/GCN, PD-BV/GCN, and pure GCN catalysts by factors of 1.35, 1.42, and 2.03, respectively. This enhanced performance was attributed to its heterostructure, which has a smaller band gap between the valence band of GCN and the conduction band of NF-BV. This configuration facilitates the transfer of photogenerated holes in the valence band of GCN to the photogenerated electrons in the conduction band of NF-BV. Additionally, a higher concentration of surface oxygen vacancies and defect sites on NF-BV trapped electrons, further inhibiting recombination and simultaneously separating electron-hole pairs, thereby significantly enhancing H₂ evolution.