Design of a novel CuBi2O4/CdMoO4 heterojunctions with nano-microsphere structure: Synthesis and photocatalytic degradation mechanism

Photocatalytic degradation based on semiconductor is a potential technology for water pollution treatment by utilizing light irradiation. As a new p-type semiconductor material, CuBi2O4 is favored by researchers due to its excellent photocatalytic properties. Herein, a group of CuBi2O4 nanospheres were synthesized by simple hydrothermal method, in which the formation and transformation process of CuBi2O4 microsphere structure was studied by adjusting the hydrothermal reaction time. On this basis, a series Z-Scheme heterojunctions with different mass ratios of CuBi2O4/CdMoO4 nanocomposites were constructed and the formation mechanism of Z-scheme heterojunction was described detailedly. The results of the study confirmed that CuBi2O4/CdMoO4 (10 %) composites exhibited excellent photocatalytic activity, with a high degradation rate of 95.36 % for MB under visible light irradiation, by comparison with bare CuBi2O4 and CdMoO4. In order to improve the quantum efficiency, doping CdMoO4 onto CuBi2O4 greatly improved the surface charge migration rate of CuBi2O4 and reduced the rate of electron-hole pairs recombination. The degradation rate of CuBi2O4/CdMoO4 (10 %) remained over 85 % after three times cycling experiments, demonstrating that the heterojunction has good repeatability and stability. The free radical trapping experiments demonstrated that the h+ and O2– were the main substances involved in photocatalytic oxidation-reduction, which match the energy band, and was consistent with the mechanism of Z-Scheme heterojunctions. This study stated that establishment of a novel CuBi2O4/CdMoO4 heterojunction composite photocatalyst is a new ideal way to carry out environmental pollution treatment and clean energy.