In Situ Construction of CuTCPP/Bi₄O₅Br₂ Hybrids for Improved Photocatalytic CO₂ and Cr(VI) Reduction

Global warming and heavy metal pollution pose tremendous challenges to human development, and photocatalysis is considered to be an effective strategy to solve these problems. Herein, copper(II) tetra (4-carboxyphenyl) porphyrin (CuTCPP) molecules were successfully in situ loaded onto Bi₄O₅Br₂ by a hydrothermal approach. A series of experimental results show that the light absorption capacity and photogenerated carrier separation efficiency were synchronously enhanced after the construction of CuTCPP/Bi₄O₅Br₂ composites. Hence, the as-prepared composites possess significantly improved photocatalytic ability for both CO₂ and Cr(VI) reduction. Specifically, CuTCPP/Bi₄O₅Br₂-2 achieves a CO generation rate of 17.14 μmol g^-1 under 5 h irradiation, which is twice as high as that of Bi₄O₅Br₂ (8.57 μmol g^-1). Besides, the optimized CuTCPP/Bi₄O₅Br₂-2 also exhibits a removal rate of 61.87% for Cr(VI) within 100 min under irradiation. Furthermore, the mechanism of CO₂ and Cr(VI) photoreduction was explored by in situ Fourier transform infrared spectroscopy and capture experiments, respectively. This work can be a reference toward the construction of photocatalysts with high activity for solar energy conversion.