Symmetry-Dependent Orbital Involvement Governing C 2 Selectivity in CO/CO 2 Reduction on M–N x B Single-Atom Catalysts

The lack of two active centers and simultaneous hydrogen evolution reaction (HER) restrict single-atom catalysts (SACs) to produce C 2 products in CO reduction reaction (CORR)/CO 2 reduction reaction (CO 2 RR). In this work, we propose SACs with a N–B neighborhood, which can obtain ethylene and ethanol as desired C 2 products through CO 2 RR in the presence of CO gas. We have identified Fe, Co, Rh, and Ni (tested 28 systems) as possible active centers in MN x B SAC to produce a C 2 product with limiting potential as low as −0.66 V (FeN 3 B) in CORR and CO/CO 2 RR. The ↓d yz orbital occupancy exhibited a significant correlation with E b_CO–CO ( R 2 = 0.74), explaining the origin of CO–CO coupling on M–N x B systems. Further, we have provided geometrical analysis and σ-electron donation (CO) and π-electron back-donation (d yz ) to understand why MN x B systems are suitable for producing C 2 products. This study opens the possibility of a future investigation in SAC for C 2 products in CORR beyond Cu.