Abstract: Inspired by the natural photosynthesis systems, the integrated harnessing and conversion of CO₂ present a promising solution for addressing the ever-rising global atmospheric concentration of CO₂. Hollow multi-shelled structured (HoMS) photocatalysts, featuring alternating shells and cavities, have recently gained recognition as efficient nano-reactors for capturing CO₂ molecules and facilitating effective photoreduction within these hierarchical structures, leveraging the preeminent enrichment effect. In this work, to augment the photocatalytic efficacy of HoMS in CO₂ treatment, highly dispersed Cu_xO nanoparticles (NPs) were incorporated on the CeO₂ shells through a polymer-assisted impregnation method to create more active sites and strengthen the interaction between the hetero-shells and CO₂ molecules. The photoreduction of the CO₂-to-CO rate under a diluted CO₂ (15%, volume fraction) atmosphere is improved by the introduction of Cu_xO NPs, with the highest CO yielding rate reaching 120 μmol·h^-1·g^-1 without any sacrificial reagents. Further comparison experiments and theoretical calculations reveal that the Cu_xO NPs promote the adsorption of CO₂ molecules in HoMS, accelerate the charge transfer efficiency, and stabilize the surface oxygen vacancies (O_vs) during the photoreduction CO₂ conversion process. We hope these easy-to-prepare HoMS nanoreactors can contribute to the effective enrichment and valorization of CO₂ in industrial exhaust gases.

Key words: Photoreduction CO₂, Cu_xO/CeO₂ hollow multi-shell structure (HoMS), Hetero-shell