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.