Multi-channel charge transfer of hierarchical TiO2 nanosheets encapsulated MIL-125(Ti) hollow nanodisks sensitized by ZnSe for efficient CO2 photoreduction

Metal-organic frameworks-based hybrids with desirable components, structures, and properties have been proven to be promising functional materials for photocatalysis and energy conversion applications. Herein, we proposed and prepared ZnSe sensitized hierarchical TiO2 nanosheets encapsulated MIL-125(Ti) hollow nanodisks with sandwich-like structure (MIL-125(Ti)@TiO2\ZnSe HNDs) through a successive solvothermal and selenylation reaction route using the as-prepared MIL-125(Ti) nanodisks as precursor. In the ternary MIL-125(Ti)@TiO2\ZnSe HNDs hybrid, TiO2 nanosheets were transformed from MIL-125(Ti) and in situ grown on both sides of the MIL-125(Ti) shell, forming sandwich-like hollow nanodisks, and the ratio of MIL-125(Ti)/TiO2 can be tuned by changing the solvothermal time. The ternary hybrids possess the advantages of enhanced incident light utilization and abundant accessible active sites originating from bimodal pore-size distribution and hollow sandwich-like heterostructure, which can effectively promote CO2 photoreduction reaction. Especially, the formed multi-channel charge transfer routes in the ternary heterojunctions contribute to the charge transfer/separation and extend the lifespan of charge-separated state, thus boosting CO2 photoreduction performance. The CO (513.1 μmol g-1h-1) and CH4 (45.1 μmol g-1h-1) evolution rates over the optimized ternary hybrid were greatly enhanced compared with the single-component and binary hybrid photocatalysts.