C−C Coupling in CO2 Electroreduction on Single Cu‐Modified Covalent Triazine Frameworks: A Static and Dynamic Density Functional Theory Study

Abstract

AbstractThe electrochemical reduction of CO2 into C2+ products represents a promising solution to completing the carbon cycle, thereby fostering a sustainable energy supply. Single‐atom electrocatalysts (SAECs) have garnered significant attention as efficient electrocatalysts for the CO2 reduction reaction. Herein, we carried out a first‐principles study on the mechanism of C−C bond formation on single‐Cu‐atom‐modified covalent triazine frameworks (Cu‐CTFs), which are a promising platform for SAECs. Static density functional calculations indicated that the dimerization of CO, which is the main mechanism for C−C bond formation on bulk Cu metals, was not favorable for Cu‐CTFs because of the lack of adjacent Cu sites for co‐adsorption of CO molecules. Rather than CO dimerization, the reaction between adsorbed *CHO and CO to produce *COCHO has a relatively low reaction energy barrier. Constrained ab initio molecular dynamics analyses revealed that the C−C bond‐forming reaction proceeds via insertion of CO at the *CHO intermediate, which has a modest activation energy of 0.09 eV. Specifically, when CO molecule is constrained to be brought close to *CHO, CO insertion between *CHO and Cu occurs at a C−C distance of 1.8 Å. This insertion reaction is the transition step for this C−C bond formation.