Symmetry-Dependent Orbital Involvement Governing C2 Selectivity in CO/CO2 Reduction on M-NxB Single-Atom Catalysts.

The lack of two active centers and simultaneous hydrogen evolution reaction (HER) restrict single-atom catalysts (SACs) to produce C2 products in CO reduction reaction (CORR)/CO2 reduction reaction (CO2RR). In this work, we propose SACs with a N-B neighborhood, which can obtain ethylene and ethanol as desired C2 products through CO2RR in the presence of CO gas. We have identified Fe, Co, Rh, and Ni (tested 28 systems) as possible active centers in MNxB SAC to produce a C2 product with limiting potential as low as -0.66 V (FeN3B) in CORR and CO/CO2RR. The ↓dyz orbital occupancy exhibited a significant correlation with Eb_CO-CO (R2 = 0.74), explaining the origin of CO-CO coupling on M-NxB systems. Further, we have provided geometrical analysis and σ-electron donation (CO) and π-electron back-donation (dyz) to understand why MNxB systems are suitable for producing C2 products. This study opens the possibility of a future investigation in SAC for C2 products in CORR beyond Cu.