Effects of structure and surface properties on the performance of ZnO towards photocatalytic degradation of methylene blue

[Display omitted] •The influence mechanism of pore size on photocatalytic degradation was revealed.•The role of pore size was correlated with photocatalytic degradation.•The catalytic performance is not positively related to the specific surface area.•The pore size of ZnO affects the adsorption process of organic pollutant.•The ideal ZnO should have a mesoporous structure with good adsorption. The mechanism of surface properties (such as specific surface area, pore size, and oxygen defects) on photocatalytic degradation was revealed and detected by means of XRD, UV-DRS, SEM, PL, XPS, BET, TEM and other characterization methods. The results show that the photocatalytic performance of four kinds of ZnO is significantly different towards the degradation of MB. Among them, the degradation efficiency sample of Z2 with mesoporous structure is as high as 92.48%, while that sample of Z1 with microporous structure is only 41.11%. Further study found that this difference was not caused by the changes of specific surface area, oxygen defects, or particle size. Difference in the catalytic degradation efficiency of ZnO could be attributed to the pore size, and ZnO with mesoporous structure has better catalytic degradation effect. The pore size determines the adsorption efficiency of organic pollutants and dissolved oxygen, and the good adsorption performance of the catalyst is the prerequisite for efficient catalytic degradation. Therefore, efficient photocatalytic degradation catalysts should be rich in oxygen defects and have a high specific surface area, but have a reasonable pore structure. Thus, the above findings will help technicians design and synthesize more efficient photocatalytic degradation catalysts.