Experimental and DFT Insights into Enhanced Charge Transfer and Efficient Photocatalytic Performance of Tubular g-C3N4/BiVO4{001} Heterojunctions

Research on the photocatalytic properties of semiconductor photocatalysts is critical for addressing environmental pollution and energy crisis. In this study, the optimal process of hydrothermal preparation of BiVO₄ was determined, and BiVO₄ with highly exposed {001} crystal facets was prepared. The photocatalytic properties of g-C₃N₄ (Graphite-phase carbon nitride) nanomaterials with different morphologies were prepared and investigated based on DFT (Density Functional Theory). Among these, tubular g-C₃N₄ (TCN), exhibiting superior photocatalytic activity, was selected to fabricate TCN/BiVO₄ nanocomposites with varying TCN contents. These composites demonstrated narrower band gaps compared to individual TCN and BiVO₄{001} photocatalysts, along with enhanced electrical and optical properties. Notably, the 3TCN/BiVO₄ nanocomposite exhibited an apparent reaction rate constant for MB (Methylene Blue) degradation of 0.042 min^–1, which is 4.5 times that of pristine TCN (0.0093 min^–1) and 2.3 times that of BiVO₄{001} (0.018 min^–1). Theoretical calculations confirm that TCN/BiVO₄ forms a structurally stable van der Waals heterojunction. The photocatalytic mechanism analysis revealed that the heterojunction suppresses the recombination of photogenerated electron–hole pairs, while the built-in electric field facilitates carrier transfer, thereby significantly improving photocatalytic performance. Additionally, repeatability and stability tests were conducted on the synthesized materials to assess their potential for practical applications. This study provides a foundation for further exploration and optimization of these materials for environmental and energy-related applications.