Efficient CeO2/ZnO heterojunction for enhanced heterogeneous photocatalytic application

Organic pollutants pose a significant challenge due to their toxicity and potential carcinogenicity, thereby posing a severe threat to the environment and human health. Heterogeneous photocatalysts offer promising advantages over traditional water purification methods due to their tunable electronic properties such as bandgap, easy separation from the reaction solution and formidable nanostructures. Herein, we prepare a CeO₂/ZnO heterostructure via simple hydrothermal synthesis. The electronic structure of this nanocomposite was tuned to achieve a band gap of ∼2.94 eV, which was between the individual bandgaps of CeO₂ and ZnO nanoparticles. In addition, the mixed valence character of Ce further enhanced the electronic properties of the CeO₂/ZnO heterostructure. The photocatalytic performance of CeO₂, ZnO and CeO₂/ZnO heterostructure was evaluated and it was found that CeO₂/ZnO heterostructure with a Zn/Ce ratio of 0.2 exhibited the highest photocatalytic activity, where the degradation efficiency was 99.28 % after irradiation for 60 min. It was mainly ascribed to the heterojunction structure of the CeO₂/ZnO nanocomposite, leading to a higher separation efficiency of electron-hole pairs and generating more superoxide radicals, which in turn improved the photocatalytic activity effectively.