Effects of Structure and Surface Properties on the Performance of ZnO with Different Morphology Towards Photocatalytic Degradation of Methylene Blue

Abstract

In this paper, UV-Vis spectroscopy is used to investigate the photocatalytic degradation performance of four different type of ZnO towards methylene blue. Moreover, XRD, SEM, PL, XPS, BET, and other characterization methods are used to analyze the influence mechanism of ZnO surface properties (such as specific surface area, pore size, and oxygen defects) on photocatalytic degradation of methylene blue. The results show that the photocatalytic performance of four kinds of ZnO having different morphology, specific surface area, pore structure, and oxygen deficiencies is significantly different towards the degradation of methylene blue. The specific surface area of the catalysts is found not to be positively correlated with their photocatalytic degradation efficiency, which is different from the current belief that a larger specific surface area results in better photocatalytic performance. On the other hand, pore size and surface oxygen defect significantly influence photocatalytic degradation efficiency. The photocatalytic degradation process of organic pollutants on the surface consists of two stages: adsorption and oxidation, and the adsorption of organic pollutants and dissolved oxygen is a prerequisite for efficient oxidative degradation. Therefore, efficient photocatalytic degradation catalysts should be rich in oxygen defects and also have a suitable specific surface area and pore structure.

Keywords: Photocatalysis, ZnO, pore structure, degradation, Oxygen defects