Ordered CoIII‐MOF@CoII‐MOF Heterojunction for Highly Efficient Photocatalytic Syngas Production

The design of advanced metal–organic framework (MOF) catalysts for solar‐driven conversion of CO 2 into syngas (CO/H 2 mixture) is beneficial. Herein, the design of a joint MOF heterostructure consisting of orderly assembled Co II ‐ and Co III ‐based Prussian blue analogs (PBAs) driven by their spontaneous lattice match in the growth process is reported. As‐prepared H/Co III ‐PBA@Co II ‐PBA cage is a mesocrystal and exhibits superior photocatalytic syngas production activity ( V CO up to 50.56 mmol g −1 h −1 , CO/H 2 = 1:1), which is among the best state‐of‐the‐art heterogeneous photocatalysts in the literature. Theoretical calculations and experimental results confirm that Co III ‐PBA exerts a stronger affinity for CO 2 molecules than Co II ‐PBA, thus serving as the active site. The built‐in electric field in the Co III ‐PBA@Co II ‐PBA heterojunction can direct the fast transport of photogenerated electrons from Co II ‐PBA to the active Co III ‐PBA. In the present case, the engineering of electronics outweighs morphological engineering to enhance the catalytic properties of Co III ‐MOF@Co II ‐MOF for CO 2 ‐to‐syngas conversion.