Heterogeneous Hollow Multi‐Shelled Structures with Amorphous‐Crystalline Outer‐Shells for Sequential Photoreduction of CO₂

Abstract Constructing delicate nano‐/microreactors with tandem active sites in hierarchical architectures is a promising strategy for designing photocatalysts to realize the challenging but attractive CO 2 reduction. Herein, hollow multi‐shelled structure (HoMS) based microreactors with spatial ordered hetero‐shells are fabricated, which achieve two‐step CO 2 ‐to‐CH 4 photoreduction. The multiple inner CeO 2 shells increase the number of active catalytic sites to ensure efficient first‐step reaction for generating CO, along with enriching the local CO concentration. The second‐step CO‐to‐CH 4 reaction is consequently induced by amorphous TiO 2 (A‐TiO 2 ) composites on the adjacent outer‐most shell, thus realizing the CO 2 ‐to‐CH 4 conversion capability using one CeO 2 @CeO 2 /A‐TiO 2 HoMS. In‐depth explorations in the microreactors provide compositional, structural, and interfacial guidance for engineering HoMS‐based microreactors with temporally–spatially ordered shells toward efficient tandem catalysis.