Photocatalytic activity and stability of ZnO particles with different morphologies

Phenol was used as a probe molecule to evaluate the photocatalytic activity of three kinds of zinc oxides, t-ZnO (tetra-needle like ZnO), n-ZnO (nano-sized particle) and c-ZnO (micro-sized particle). The photostability and effects of surface area, morphology of the photocatalyst on the photocatalytic activity were investigated in the present paper. Moreover, effects of initial concentration of the phenol and content of the photocatalysts on phenol degradation rate were systematically investigated. The results of the comparison experiments indicate that the three kinds of zinc oxides had photocatalytic activity under UV-light, and no direct relationships between the photocatalytic activity and the surface area were found for the different original ZnO particles. Instead, it is found that the particle morphology significantly affects the photocatalytic activity. The t-ZnO has a better stability and photocatalytic activity than those of n-ZnO and c-ZnO. The phenol degradation reaction follows a first-order reaction, and the degradation rate is reduced as a function of increase in the initial concentration of phenol. The optimal content of the photocatalyst is 2 g/L.