Zn-based metal–organic framework with intramolecular hydrogen bond for the electroreduction of CO2 to formate.

Metal–organic frameworks (MOFs) have important research value in the field of electrochemical CO2 reduction reaction because of their rational design. Here, a new MOF-CH3 was prepared via a simple solvothermal method by using Zn as the metal center and 1,2,4-triazole and 2-methyl-terephthalic acid as ligands for electrocatalytic CO2 reduction. The single-crystal X-ray diffraction shows that MOF-CH3 is N, O-coordinated 3D columnar layer framework with intramolecular hydrogen-bonding interactions. The powder X-ray diffraction for MOF-CH3 displays the good crystallinity of 24 h in 0.5 mol L−1 KHCO3 electrolyte solution. The electrochemical CO2 reduction reaction tests indicate that the MOF could effectively convert CO2 to formate, and the highest Faradaic efficiency of formate (FEformate) is 76.5% at − 1.37 V (vs. reversible hydrogen electrode) with a partial current density of formate of − 12.1 mA cm−2. The performance of MOF-CH3 is better than that of the reported other two structural analogues MOF-NH2 with FEformate of 55.7% at − 1.57 V or MOF-H with FEformate of 73.5% at − 1.37 V in aqueous CO2-saturated electrolyte solution. The work shows that the performance could be improved by regulating the microenvironment of MOF catalysts. [ABSTRACT FROM AUTHOR]