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

Constructing delicate nano-/microreactors with tandem active sites in hierarchical architectures is a promising strategy for designing photocatalysts to realize the challenging but attractive CO₂ reduction. Herein, hollow multi-shelled structure (HoMS) based microreactors with spatial ordered hetero-shells are fabricated, which achieve two-step CO₂ -to-CH₄ photoreduction. The multiple inner CeO₂ 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-CH₄ reaction is consequently induced by amorphous TiO₂ (A-TiO₂ ) composites on the adjacent outer-most shell, thus realizing the CO₂ -to-CH₄ conversion capability using one CeO₂ @CeO₂ /A-TiO₂ 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.