TiO2/Bi2O2CO3 heterojunction for enhanced photocatalytic hydrogen production performance: Photogenerated carrier separation

The high electron-hole complexation rate and wide band gap of TiO₂ are significant hindrances to photocatalytic hydrogen production. It has become a challenge to design a photocatalyst that improves the separation efficiency of photogenerated carriers. Bismuth-based hierarchical oxides with high chemical stability and good photocatalytic activity. In this study, we employed hydrothermal and physical mixing techniques to fabricate TiO₂/Bi₂O₂CO₃ (TB) type II heterojunctions, aiming to enhance the efficiency of separating photogenerated carriers in the materials. The findings from the BET analysis indicate that the incorporation of a heterojunction structure leads to a significant increase in the material’s specific surface area. This, in turn, facilitates the exposure of more reactive sites of the catalyst material. The TPR, EIS, and PL findings indicate that the TB composites exhibit superior efficiency in separating photogenerated carriers and lower resistance to charge transfer when the Bi₂O₂CO₃ (BOC) mass fraction is at 5 %, resulting in a photocurrent intensity of approximately 1.9 μA/cm². As a result, TB composites demonstrated remarkably efficient performance in producing hydrogen through photocatalysis. The hydrogen production rate of the optimal TB-5 ratio reached 3906.38 μmol g⁻¹ h⁻¹, which was 27 times higher compared to pure TiO₂. Additionally, the apparent quantum efficiency (AQY) achieved an impressive value of 5.028 %. The current study presents a new approach for developing low-cost TiO₂-based photocatalysts with high efficiency in separating photogenerated carriers and producing hydrogen through photocatalysis.