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.