A direct Z-scheme oxygen vacant BWO/oxygen-enriched graphitic carbon nitride polymer heterojunction with enhanced photocatalytic activity

A high-performance micro-nano photocatalyst is urgently needed in the green and economical photocatalytic process for energy utilization and organic pollution control. Herein, a 3D Z-scheme heterojunction consisting of oxygen vacant bismuth tungstate nanosheets (BWO-OV) and oxygen-enriched graphitic carbon nitride (OCN) was developed, which shows large specific surface area and good electrical conductivity. A built-in electric field can be formed in this 3D structure, which accelerates the interfacial charge transfer. The oxygen vacancies of BWO-OV allow the formation of local defect energy levels below conduction band, which can improve the light harvesting capability. The oxygen-rich structure of OCN benefits the oxygen reduction to generate H2O2, and the black body nature enhance the light absorption capability. As expected, the BWO-OV/OCN heterojunction showed unusual photocatalytic efficiency toward the degradation of tetracycline (TC) (0.047 min(-1)) under visible light. The photogenerated holes (h(+)) and superoxide radicals (center dot O-2(-)) were found to play the main roles in TC degradation process. Moreover, the effect of actual water matrix on TC degradation over BWO-OV/OCN heterojunction was investigated. This work highlights a feasible way to design high-efficiency oxygen vacant bismuth-based photocatalysts, which shows the potential for real wastewater treatment.