Chemistry of CeO2-derived nanocomposites photocatalysts for environment monitoring and energy conversion

Photocatalysis is an important process in energy conversion and environmental usage because of its feasible, profitable, and environmentally safe benefits. Coordination chemistry of the CeO₂ is gaining significant interest because its nanocomposites show unique characteristics namely optically active, wide bandgap (E_g), reversible valence states (Ce^3+/4+), rich defect architectures, high O₂ storage capability, ionic conductivity, and exceptional chemical resistance. Systematically summarized the importance of synthesis methods, particle morphology, and crystal structure aiming at how to heighten the efficacy of CeO₂-derived hybrid heterojunction (HHJ) photocatalyst. Selection of an appropriate synthesis method and morphology of the composite materials are beneficial in inhibiting the rapid electron-hole (e⁻-h⁺) recombination, improvement in visible light adsorption, and large generation of e⁻-h⁺ pairs to accelerate the photocatalysts activities. Various modification approaches include elemental doping (metal/non-metal doping), heterojunction construction (lower/wide E_g semiconductors (SCD), carbon, conducting polymeric materials), imperfection engineering, and multicomponent hybrid composites. These methods assist as a valuable resource for the rational design of effective CeO₂-based composite photocatalysts for sustainable development owing to the enhancement of oxygen species mobility, rapid charge transfer, maximum visible light captivation and slow down the charge recombination rate with increase photogeneration of e⁻-h⁺ pairs. Also examines the advancements made in CeO₂ conjugated hybrid composites in photo-oxidation of wastewater effluents (antibiotic/organic dyes/chemical/pharmaceutical), heavy metal removal, H₂ production, CO₂ reduction, and H₂O splitting applications. Subsequently, the difficulties and fundamental ideas behind several heterojunction photocatalysts encountered by CeO₂-based composites are examined, and future directions for their development are suggested.