Constructing Defective Heterojunctions of BiOBr Nanosheets and Hollow NH 2 -functionalized MOFs for Visible-light-driven CO 2 Reduction with Nearly 100% CO Selectivity by Pure H 2 O.

To rationally design photocatalysts with high generation rate and selectivity of target product remains an ongoing challenge for CO 2 conversion in pure H 2 O. Herein, from the viewpoint of enhancing the separation efficiency of photoinduced electron-hole pairs and the adsorption ability of CO 2 molecule, we have constructed a series of Z-scheme defective heterojunctions of BiOBr nanosheets and hollow NH 2 -functionalized metal-organic framework (MOF) MIL-125 with Ti ions as metal centers (noted as NH 2 -MIL-125(Ti)). Systematic characterization demonstrates that the BiOBr nanosheets are anchored on the surface of hollow NH 2 -MIL-125(Ti), which facilitates the efficient visible-light-driven catalytic reduction of CO 2 to CO with nearly 100% selectivity by pure H 2 O. Especially, the CO generation rate of optimized catalyst with oxygen vacancies reaches 459.7 μmol g -1  h -1 , which is higher than those of all the previously reported photocatalysts without sacrificial reagents. This approach provides a new insight for using inorganic semiconductors to fabricate semiconducting MOFs for high-efficiency photocatalytic reduction CO 2 into value-added chemicals by pure H 2 O.