CeO2 and CeO2-based nanomaterials for photocatalytic,antioxidant and antimicrobial activities

Cerium oxide (CeO₂), one of the most significant rare-earth oxides, has attracted considerable interest over the past decades. This is primarily due to the ease in Ce³⁺/Ce⁴⁺ redox ability as well as other factors that affect the efficacy of CeO₂ and CeO₂-based materials. CeO₂ and CeO₂-based materials have shown enhanced responses in catalytic and photocatalytic activities for environmental and biological applications. In addition, the formation of Ce³⁺ and oxygen vacancies in CeO₂ has aided in enhancing CeO₂ activities. In order to produce oxygen-deficient CeO₂ and CeO₂-based materials, a variety of synthesis methods were used and are highlighted in this review. Therefore, this review compiles and discusses the mechanisms that involve oxygen vacancies, defects, and Ce³⁺ formation for environmental applications, such as photocatalytic dye degradation, photocatalytic CO₂ reduction, and non-colored pollutants removal. The biological applications of CeO₂, such as antioxidant enzyme mimetic, antioxidant reactive oxygen species/reactive nitrogen species, and antimicrobial activities, are also discussed. Additionally, future prospects are also suggested for future development and detailed investigations.