Revealing well-defined cluster-supported bi-atom catalysts for enhanced CO2 electroreduction: a theoretical investigation.

It remains a great challenge to explore high-performance electrocatalysts for the CO2 reduction reaction (CO2RR) with high activity and selectivity. Herein, we employ first principles calculations to systematically investigate an emerging family of extended surface catalysts, bi-atom catalysts (BACs), in which bimetals anchored on graphitic carbon nitride (g-CN), for the CO2RR; and propose a novel framework to boost the CO2RR via incorporation with well-defined clusters. Among 28 BACs, five candidates (Cr2, CrFe, Mn2, MnFe and Fe2/g-CN) are first selected with efficient CO2 activation and favorability for CO2 reduction over H2 evolution. Fe2@g-CN is then served as a superior electrocatalyst for the CO2RR with low limiting potentials (UL) of -0.58 and -0.54 V towards C1 and C2 products. Intriguingly, the CO2RR performance of pure Fe2@g-CN could be controlled by tunable Fe atomic cluster integration. In particular, the presence of an Fe13 cluster could strengthen the CO2 adsorption, effectively deactivate H, and intriguingly break the adsorbate (CO* and CHO*) scaling relation to achieve the distinguished CO2RR with a lowered UL to -0.45 V for the C1 mechanism, which is attributed to the exceptional charge redistribution of bimetals modulated by Fe13. Our findings might open up possibilities for the rational design of BACs towards the CO2RR and other reactions.