Zn/Ce metal-organic framework-derived ZnO@CeO2 nano-heterojunction for enhanced photocatalytic activity

Photocatalysis is a promising method for the decontamination of wastewater using renewable energy source. However, photocatalysts frequently exhibit low photocatalytic degradation performance because the photogenerated electron-hole pairs undergo rapid recombination. Nevertheless, the formation of nanoheterojunction interfaces in photocatalytic materials provides a route to separates the photogenerated charge carriers. Therefore, in this study, ZnO@CeO2 nanocomposites were prepared by pyrolyzing a coprecipitated Zn@Ce metalorganic-framework precursor, and the effect of the pyrolysis temperature on the photocatalytic performance was investigated. The nanocomposites were composed of hexagonal wurtzite ZnO and cubic CeO2 and possessed a distinct hetero-interface between ZnO and CeO2. The photodegradation performance of the photocatalyst for the degradation of model contaminants (organic dyes) was assessed, and a mechanism for the photocatalytic degradation is proposed. Crucially, the heterojunction interface induced a built-in electric field, which resulted in the accumulation of photoelectrons and holes in the more negative CeO2 conduction band and positive ZnO valence band, respectively, thereby achieving photocarrier separation.