Fabrication of BiOBr/CAU-17 Z-scheme heterojunction composites with enhanced photocatalytic performance for Rhodamine B degradation

Photocatalytic degradation of dye wastewater has great potential due to its eco-friendly, simple, and solar energy-based characteristics. In this work, an energy-saving and convenient precipitation method was explored to compound two classical photocatalyst materials BiOBr and CAU-17. The Z-scheme heterojunction decreases the agglomeration of the BiOBr nanosheets and addresses the issue of the low photogenerated carrier participation rate of CAU-17. The solvothermal method was used to prepare CAU-17 nanorods, and then BiOBr nanosheets were grown on them at room temperature to fabricate BiOBr/CAU-17 composites. The samples were characterized by XRD, SEM, TEM, XPS, DRS, PL, EIS, and other techniques. The photodegradation performance was tested using Rhodamine B (RhB) as the model pollutant. The 80% BiOBr/CAU-17 composite (0.1 g/L) exhibited a degradation rate of 99.41% for RhB under simulated sunlight in 60 min, with an apparent rate constant of 0.0631 min⁻ 1 , which is 3.45 times faster than pure BiOBr and 315.5 times faster than CAU-17. Free radical capture and EPR tests confirmed that · O 2 ⁻ and h⁺ were the main active species in the process, and a reasonable photocatalytic mechanism is proposed. Additionally, cyclic tests are conducted to confirm the stability and durability of the composite, proving the potential of BiOBr/CAU-17 composites for efficient and sustainable photocatalytic applications.