Evaluation of photocatalytic production of active oxygen and decomposition of phenol in ZnO suspensions

Abstract

Abstract Photocatalytic production of hydroxyl radical (·OH) and superoxide anion (·O 2 − ) and decomposition of phenol in ZnO suspensions were studied in the present paper. Nano‐sized ZnO (n‐ZnO) produced by chemical precipitation method with particle size of ca. 50 nm and commercial ZnO (c‐ZnO) produced by indirect method (oxidation of the metal in oxygen) with particle size of ca . 500 nm were used in this work. The photocatalytic production of ·OH and superoxide anion ·O 2 − in the suspensions of ZnO were measured by electron paramagnetic resonance (EPR) spectrometer, and the results indicate that the c‐ZnO generated more ·OH and ·O 2 − than the n‐ZnO. The photocatalytic activity of ZnO was evaluated by the decomposition of phenol in the suspensions, and the results show that the c‐ZnO has stronger activity than the n‐ZnO, which is in accordance with the results of the production of active oxygen. These results reveal that the particles size is not the main factor that influences the photocatalytic activity of ZnO. The preparation method, which can affect the characteristics of surfaces and the defects inside the ZnO, may have some effect on the photocatalytic activity.