Newly constructed Z-scheme Cu2ZnSnS4/BiOBr heterostructure for high-efficient photocatalytic applications

The structural design of semiconductor photocatalyst is a key factor to achieve high-efficient dye wastewater purification, in which the common drawbacks of weak redox kinetics, fast carrier recombination and insufficient optical response should be addressed, but still challenging. Herein, using two-step hydrothermal/solvothermal process, a direct Z-scheme heterostructured photocatalyst is newly constructed by coupling Cu2ZnSnS4 (CZTS) and BiOBr (BOB) nanosheets. Under the synergistic action of the narrow-gap photosensitive characteristics of CZTS and BOB's intrinsic interlayered electric field, such Z-scheme CZTS/BOB can possess significantly enhanced photocatalytic activity for photo-degrading methyl orange, having the highest degradation efficiency of up to 99% within 40 min with the degradation rate of 0.0907 min-1, which is about 3.3 and 37.8 times higher compared with the bare BOB (0.0273 min-1) and CZTS (0.0024 min-1), respectively. Through detailed analysis, such direct Z-scheme heterostructures can facilitate to broaden visible light response, efficiently separate pho-togenerated carriers, inhibit recombination and enhance the redox capacity as well, thus contributing to the improved photocatalytic efficiency. This study might provide a new idea for the construction of BOB-based high efficiency catalysts.