Defect engineering of ZnO for electron transfer in O3 catalytic decomposition

Abstract

Nowadays, it is necessary to discover the interactions of O3 with metal oxides in order to synthesize active O3 degradation catalysts. Herein, ZnO is adopted as a model and the crystal defects are tuned by annealing in H2 and O2, and by doping with Ga and Li. The H2 annealed ZnO behaves far higher activity towards 20 ppm O3 than those as-obtained and O2 annealed ones, and the activity can be further improved by doping with Ga donors and Li acceptors. The mechanism investigation shows that the oxygen vacancy induced by H2 annealing favors the activity while the oxygen interstitials depress it, implying that there existed electron transfer between crystal defects, O3 and the intermediate species. Furthermore, the deactivation of catalyst is attributed to the filling out of the oxygen vacancy. All these results provide fundamental understanding for further improvement of O3 degradation catalysts.