Dual-atom active sites embedded in two-dimensional C2N for efficient CO2 electroreduction: A computational study

Double-atom catalysts (DACs) have emerged as an enhanced platform of single-atom catalyst for promoting electrocatalytic CO2 reduction reaction (CO2RR). Herein, we present a density-functional theory study on CO2RR performance of seven C2N-supported homo- and heteronuclear DACs, denoted as M-2@C2N. Our results demonstrate that there exists substantial synergistic effect of dual-metal-atom N2M2N2 active site and C2N matrix on O=C=O bond activation. The dual-atom M-2 sites are able to drive CO2RR beyond C-1 products with low limiting potential (U-L). Specifically, C2H4 formation is preferred on FeM@C2N (M = Fe, Co, Ni, Cu) versus CH4 formation on CuM@C2N (M = Co, Ni, Cu). Furthermore, *CO+*CO co-binding strength can serve as a descriptor for CO2RR activity for making C-2 products such that the moderate binding results in the lowest U-L. Remarkably, C-affinity matters most to C-C bond coupling and C2H4 formation while both C- and O-affinity control CH4 formation. Our results provide theoretical insight into rational design of DACs for efficient CO2RR. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.