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

Abstract

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 (U_L) 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 U_L 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.