Modification of Co3O4/CuBi2O4 composite for photocatalytic degradation of methylene blue dye

Herein, we report the synthesis of cobalt oxide ( Co3O4), copper bismuth oxide (CuBi2O4), and Co3O4/CuBi2O4 composite by a co-precipitation method. The effect of Co3O4 addition on phase composition and microstructure of CuBi2O4 is studied using X-ray diffraction, transmission electron microscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy. The surface area and pore structure have been studied by nitrogen adsorption-desorption isotherm based on Brunauer-Emmett-Teller theory. Optical properties of all photocatalysts are also investigated by diffuse reflectance spectra UV-Vis measurements. The intensity of photoluminescence is also used to measure the electron hole recombination in the unmodified Co3O4 and CuBi2O4 compared with the composite sample. The photocatalytic activities of the prepared samples are evaluated under visible light in the presence of the target pollutant, methylene blue (MB). The results show that coupling Co3O4 with CuBi2O4 could effectively promote photogenerated electron transfer in heterojunction, which is able to retard recombination process and thus improve their photocatalytic performance. In this system, Co3O4/CuBi2O4 exhibits the best photocatalytic activity in degrading 22% of MB within 120 min under visible irradiation. The apparent reaction rate constant (k) of the composite is 3.8 times greater than that of pure CuBi2O4, and around 1.3 time compared to pure Co3O4. Hence, the formation of a heterojunction between two photocatalysts is an efficient way to degrade the environmental pollutants in wastewater with the usage of photon energy, that can be further adapted for practical application.