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

Abstract

The design of advanced metal–organic framework (MOF) catalysts for solar‐driven conversion of CO2 into syngas (CO/H2 mixture) is beneficial. Herein, the design of a joint MOF heterostructure consisting of orderly assembled CoII‐ and CoIII‐based Prussian blue analogs (PBAs) driven by their spontaneous lattice match in the growth process is reported. As‐prepared H/CoIII‐PBA@CoII‐PBA cage is a mesocrystal and exhibits superior photocatalytic syngas production activity (VCO up to 50.56 mmol g−1 h−1, CO/H2 = 1:1), which is among the best state‐of‐the‐art heterogeneous photocatalysts in the literature. Theoretical calculations and experimental results confirm that CoIII‐PBA exerts a stronger affinity for CO2 molecules than CoII‐PBA, thus serving as the active site. The built‐in electric field in the CoIII‐PBA@CoII‐PBA heterojunction can direct the fast transport of photogenerated electrons from CoII‐PBA to the active CoIII‐PBA. In the present case, the engineering of electronics outweighs morphological engineering to enhance the catalytic properties of CoIII‐MOF@CoII‐MOF for CO2‐to‐syngas conversion.