Controlling oxygen vacancies and enhanced visible light photocatalysis of CeO2/ZnO nanocomposites

[Display omitted] •Rich oxygen vacancy CeO2/ZnO nanomaterials synthesized via a facile sol-gel method.•Oxygen vacancy concentration of CeO2/ZnO nanocomposites could be controlled by varying the ratio of air:N2 in the process of calcination.•Enhanced oxygen vacancy concentration contributed to absorption efficiency of visible light of photocatalyst.•Enhanced photocatalysis could be explained by the synergistic effect of oxygen vacancy and CeO2/ZnO heterojunction. Oxygen vacancy in semiconductors plays crucial roles in the efficiency enhancement of photocatalysis. In this paper, a facial method to control oxygen vacancy concentration of CeO2/ZnO nanocomposites was developed by varying the ratio of air:N2 in the process of calcination. Detailed analysis based on X-ray photoelectron spectroscopy (XPS) revealed that the oxygen vacancy concentration in CeO2/ZnO nanostructures was richer than that in unmixed ZnO, and reached its maximum value when the ratio of air:N2 in calcination atmosphere was 2:8 or 4:6. The photocatalytic performance was investigated by the degradation of Rhodamine B (RhB) under visible light irradiation. The CeO2/ZnO nanoparticles with air:N2 = 2:8 showed the highest photocatalytic activities owing to the highest oxygen vacancy concentration. The transmission electron microscopy (TEM) results indicated that an intimate contact between ZnO and CeO2 was formed. It was possible that the improved photocatalytic activity was caused by the synergistic effect of CeO2/ZnO heterojunction and oxygen vacancy in CeO2/ZnO nanocomposites.