Influence of Au content on photocatalytic performance of C@ZnO@Au hollow nanospheres

Schematic diagram of the proposed mechanism for enhanced photocatalytic activity (a), and energy band diagram of C@ZnO@Au hollow spheres under UV light irradiation. [Display omitted] •Mesoporous C@ZnO@Au hollow spheres were synthesized by a stepwise method.•Photocatalytic performance of the samples is a function of the Au content.•A range of Au content causes photocatalytic performance to increase.•The changes in photocatalytic performance are a result of a variety of competing mechanisms. Mesoporous C@ZnO@Au hollow spheres were synthesized through a stepwise method. The photocatalytic activities of the samples to RhB under UV irradiation were investigated. The sample with a 1/1000 mol ratio of Au/ZnO was found to have the best photocatalytic activity, which is far better than P25. The improved performance could come from the larger specific area induced by mesoporous hollow nanostructure, enhanced light absorption, or improved photogenerated electron-hole pair separation. Sample performance is a function of Au content. Too much or too little Au content decreases sample performance. The changes in performance according to Au content are a result of various competing mechanisms. This work serves to help us to better understand the important roles of Au content in the fabricated nano-heterojunction catalysts and also provide us with a feasible route to improve UV photocatalytic activities of ZnO and other metal oxides.