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

The CO2RR performance of M2@C2N DACs were computationally explored. It is revealed that Caffinity of dual-atom M2 site matters most to CC bond coupling and C2H4 formation while both C- and O-affinity control CH4 formation. [Display omitted] •CO2RR on C2N-supported homo- and heteronuclear DACs were computationally explored.•Synergistic effect of N2M2N2 active site on CO2 activation was revealed.•Strong C-affinity of M2 favors C-C coupling and C2H4 formation in CO2RR.•Both C- and O-affinity of M2 control CH4 formation in CO2RR. 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 M2@C2N. Our results demonstrate that there exists substantial synergistic effect of dual-metal-atom N2M2N2 active site and C2N matrix on OCO bond activation. The dual-atom M2 sites are able to drive CO2RR beyond C1 products with low limiting potential (UL). 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 C2 products such that the moderate binding results in the lowest UL. Remarkably, C-affinity matters most to CC 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.