Synthesis and Characterization of Bimetallic ZnCo-ZIF-71 with Defect for an Efficient Catalytic CO 2 Conversion

A bimetallic zinc and cobalt zeolitic imidazolate framework (ZnCo-ZIF-71) catalyst was synthesized using metal acetate and 4,5-dichloroimidizole in a methanol solution. Various physicochemical analytical techniques were employed to characterize the synthesized catalyst and to confirm the existence of uniform distribution of Zn and Co atoms throughout the catalyst system. CO 2 -epoxide cycloaddition reactions were subsequently carried out to test the performance of ZnCo-ZIF-71. The bimetallic ZIF showed a higher conversion of epoxide compared to that of the corresponding monometallic ZIF (Zn-ZIF-71 and Co-ZIF-71), likely due to the prevalence of linker defects in bimetallic ZIF system. The degree of linker defects in bimetallic ZIFs was characterized based on molecular simulations. The mechanism for the solvent-free CO 2 -epoxide cycloaddition reaction catalyzed by ZnCo-ZIF-71 was proposed following the XAFS analysis and DFT calculations.