Construction of hierarchical CuBi2O4/Bi/BiOBr ternary heterojunction with Z-scheme mechanism for enhanced broad-spectrum photocatalytic activity

A novel Z-scheme CuBi2O4/Bi/BiOBr ternary heterostructured photocatalyst was developed by a simple hydrothermal method. The structural, morphologic, optical and electronic properties were systematacially characterized. The metal Bi was confirmed by the XRD, XPS and SEM, which served as bridge between CuBi2O4 and BiOBr, promoting the charge transfer. The optimized CuBi2O4/Bi/BiOBr heterostructure possessed superior photocatalytic degradation efficiency (81%) towards ciprofloxacin (CIP), which was 2.38- and 1.25-fold higher than that of pure CuBi2O4 and BIOB, respectively. The origin of the improved photocatalytic performance of CuBi2O4/Bi/BiOBr heterostructure was attributed to the enhanced light absorption combined with Z-scheme heterostructure. Additionally, the degradation efficiencies of CuBi2O4/Bi/BiOBr heterostructure towards Methylene blue (MB), Lanasol Red 5B (LR5B), Rhodamine B (RhB), Bisphenol A (BPA) and phenol were 73%, 99%, 99%, 45% and 48%, respectively. However, the simultaneous photocatalytic degradation exhibited the competitive actions between CIP and other organic pollution for radical, resulting in poor degradation performance for CIP. The experimental factor towards degradation efficiency of CIP was investigated. The momentous contribution of superoxide radicals (•O2−) and hydroxyl radical (•OH) were confirmed by the trapping experiment and electron paramagnetic resonance (EPR), which help us deduce Z-scheme charge transfer mechanism, improving the photocatalytic activity.