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 (Cr-2, CrFe, Mn-2, MnFe and Fe-2/g-CN) are first selected with efficient CO2 activation and favorability for CO2 reduction over H-2 evolution. Fe-2@g-CN is then served as a superior electrocatalyst for the CO2RR with low limiting potentials (U-L) of -0.58 and -0.54 V towards C-1 and C-2 products. Intriguingly, the CO2RR performance of pure Fe-2@g-CN could be controlled by tunable Fe atomic cluster integration. In particular, the presence of an Fe-13 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 U-L to -0.45 V for the C-1 mechanism, which is attributed to the exceptional charge redistribution of bimetals modulated by Fe-13. Our findings might open up possibilities for the rational design of BACs towards the CO2RR and other reactions.