Efficient CeO2/ZnO heterojunction for enhanced heterogeneous photocatalytic application.

CeO 2 /ZnO heterostructure with optimized composition has improved structural and electronic properties for photocatalytic degradation of azo dyes. [Display omitted] • Various compositions of CeO 2 /ZnO heterostructure were prepared. • The morphological, chemical and electronic properties of these heterostructures were determined. • Photocatalytic degradation of methylene blue dye was carried out up to 99.28% with CeO 2 /ZnO heterostructure. • The mechanism of photocatalytic degradation was thoroughly discussed. 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 CeO 2 /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 CeO 2 and ZnO nanoparticles. In addition, the mixed valence character of Ce further enhanced the electronic properties of the CeO 2 /ZnO heterostructure. The photocatalytic performance of CeO 2 , ZnO and CeO 2 /ZnO heterostructure was evaluated and it was found that CeO 2 /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 CeO 2 /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. [ABSTRACT FROM AUTHOR]