| Highly photoactive nanocrystalline ZnO thin films were prepared by sol-gel process. Structural features, surface morphologies and UV absorption spectra were studied by XRD, AFM and UV-Vis-Nir scanning spectrophotometer. The influence of substrates, annealing temperatures, degradation temperatures, original concentration of phenol and air flux on photocatalytic activity have also been studied. The principles and methods for enhancing nano-ZnO photocatalystic activity were discussed. The effective approaches were metal ion-doping, precious metal deposition and ion-implanting. Furthermore, the loss and regeneration of photocatalytic activity were attempted as well. And the results show the best conditions, the substrate is quartz, annealing temperature is 300℃, degradation temperature is between 25℃ and 40℃, air flux is 40ml/min, the lower original concentration, the higher degradation rates. The doping modified ZnO photocatalysts' absorbing bounds moved to visible light, and their photocatalytic activities were enhanced with different degree. For photocatalysts having lost activity, washing with H2O2 can resume the activity and satisfy the repeatable experiments. Excellent adhesion as well as recyclable and efficient degradation in phenol of ZnO thin films were found in this experiment.
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