Formation of CeO₂/NiO composites with intergrowth superstructures for photocatalytic CO₂ reduction

The global climate crisis and the excessive consumption of fossil fuels have made photocatalytic CO₂ reduction a promising strategy for achieving carbon neutrality. However, the inherent chemical inertness of CO₂ and the rapid recombination of photogenerated charge carriers still limit its efficiency. In this study, a CeO₂/NiO composite catalyst with an octahedral orthogonal structure was synthesized by oxidation treatment using a nickel-based cyanide-bridged metal frameworks as the precursor. Characterization analyses revealed that the CeO₂/NiO composite structure significantly enhanced charge carrier separation efficiency through interfacial synergistic effects, while moderate surface lattice defects improved CO₂ adsorption and activation. Under visible light irradiation, the CO generation rate of the CeO₂/NiO reached 30.1 mmol·g⁻¹·h⁻¹, which was significantly higher than that of the original precursor, and it exhibited remarkable stability (with activity maintained at over 95% after five cycles). Mechanistic studies indicated that the optimized band structure provided sufficient thermodynamic driving force for CO₂ reduction. The interfacial electron transfer channels facilitated the directional migration of photoelectrons, while surface oxygen vacancies optimized the adsorption energy of the critical intermediate (*COOH) through localized charge redistribution.