Copper(II) Frameworks with Varied Active Site Distribution for Modulating Selectivity of Carbon Dioxide Electroreduction.

Metal-organic frameworks (MOFs) can be utilized as electrocatalysts for CO reduction reaction (CORR) due to their well dispersed metal centers. However, the influence of metal node distribution on electrochemical CORR was rarely explored. Here, three Cu-MOFs with different copper(II) site distribution were employed for CO electroreduction. The Cu-MOFs [Cu(L)SO]·HO (), Cu(L)(HO)·HO (), and Cu(L)(HO) () were achieved by using the same ligand 1,3,5-tris(1-imidazolyl)benzene (L) but different Cu(II) salts. The results show that the Faraday efficiency of CO (FE) for is 4 times that of the FE, while the FE of is twice that of the FE. As for , there is not much difference between FE and FE. Such difference may arise from the distinct electrochemical active surface area and charge transfer kinetics caused by different copper site distribution. Furthermore, the different framework structures also affect the activity of the copper sites, which was supported by the theoretically calculated Gibbs free energy and electron density, contributing to the selectivity of CORR. This study provides a strategy for modulating the selectivity of CORR by tuning the distribution of the active centers in MOFs.