Hierarchical ZnO Decorated with CeO2 Nanoparticles as the Direct Z-Scheme Heterojunction for Enhanced Photocatalytic Activity.

Development of a high-efficiency heterojunction with an improved photocatalytic property is regarded as a promising way to decontaminate wastewater. Herein, the direct novel Z-scheme heterojunction formed between CeO2 nanoparticles and hierarchical ZnO was synthesized through the wet chemistry method and then the heat-treatment technique. The as-synthesized ZnO/CeO2 composites display highly enhanced photocatalytic rhodamine B (RhB) degradation compared with pristine ZnO and CeO2. Specifically, ZnO/CeO2-3 (mass fraction of CeO2, 30%) shows good photostability and the best removal efficiency for photodegradated RhB, which are almost 2.5 and 1.7 times than pristine ZnO and CeO2, respectively. On the basis of the detailed characterizations and the degradation behavior of as-prepared samples over RhB, the formed heterojunction between the hierarchical ZnO and CeO2 nanoparticles is confirmed as the direct Z-scheme heterojunction. The heterojunction system shows fast transfer, high-efficiency separation, and long lifetime of photoinduced charge carriers, as well as enhanced redox capacity. This study affords a novel approach to construct ZnO-based Z-scheme heterojunctions for the photocatalytic applications.