CeO2-based functional materials: Advancing photo and electro-driven catalysis for environmental remediation and energy conversion

Transition metal oxides have drawn considerable interest due to their distinctive structure, multiple notable oxidation states, non-toxicity, and environmental sustainability. In the field of catalysis research, a particularly promising and urgent area of focus is the creation of stable and highly effective catalysts based on transition metal oxides. The twin global issues of environmental degradation and energy scarcity demand the creation of novel eco-friendly solutions. These challenges underscore the urgent need for advancing cutting-edge sustainable technologies. Currently, significant attention is focused on photocatalysis, electrocatalysis, and photoelectrocatalysis as viable strategies for addressing energy conversion and environmental remediation challenges. CeO₂ has emerged as a catalyst of great promise, primarily due to its unique surface characteristics and distinctive 4f electron configuration. Especially, the coordination of Ce⁴⁺ with O₂⁻ in CeO₂, involving Ce(IV) to O(II) charge transfer, yields a critical defect and a highly active surface. Nevertheless, the limited light-absorbing capacity and electrical conductivity of traditional CeO₂ hinder its practical application. Consequently, developing diverse strategies to introduce abundant defects and active sites is pivotal for expanding the catalytic applications of CeO₂. This review offers an in-depth overview of recent progress in CeO₂-based catalytic systems for photocatalytic, electrocatalytic, and photoelectrocatalytic applications, with a focus on sustainable energy production and environmental pollution mitigation. This review emphasizes the synthesis methods of diverse tailored microstructures (including microspheres, hollows, core-shells, and polytopes) of CeO₂, as well as strategies to enhance its catalytic activity via elemental doping, atomic loading, and coupling with oxides, MOFs, and carbonaceous materials to modulate the electronic coordination structure. Additionally, the discussion focuses on the catalytic activities, stabilities, and reaction mechanisms of CeO₂-based catalysts, including oxygen vacancy defects, interfacial effects, bonding of reaction product intermediates to catalyst metal active sites, and metal-carrier interactions. Furthermore, this review presents a detailed description of quantitative characterization methods for evaluating oxidation states and oxygen vacancies in CeO₂-based materials. Furthermore, the review highlights the current challenges and potential prospects in this research area. By providing a comprehensive update on the latest advances, this review aims to facilitate the informed design of high-performance CeO₂-based composite catalysts, serving as a valuable resource for the pursuit of sustainable development goals.