Electrochemical CO2 Reduction on Janus Dual-Atom Catalysts: Critical Role of Oxygen Coordination and an Effective Descriptor.

Dual-atom catalysts (DACs) embedded in nitrogen-doped graphene have been widely studied for electrochemical CO2 reduction (CO2R), primarily yielding CO. However, achieving selectivity for C1 hydrocarbons remains challenging. Here, 32 Janus DACs (J-M'M) are designed and investigated for CO2R using density functional theory (DFT) calculations, identifying 13 capable of producing methanol and methane. Notably, J-FeCo and J-CoNi exhibit favorable limiting potentials (-0.38 and -0.45 V vs. RHE) for CH3OH and CH4 production, respectively, based on constant-potential calculations. Compared to normal DACs (N-M'M), Janus DACs demonstrate enhanced initial CO2 hydrogenation and stronger CO adsorption. Oxygen coordination in J-FeCo and J-CoNi induces a downshift/upshift of majority-/minority-spin energy levels of dz2, dyz, and dxz orbitals toward the Fermi level relative to N-FeCo and N-CoNi, strengthening the bonding state and weakening the antibonding state, thereby improving CO adsorption. Furthermore, an effective descriptor based on atomic features is identified to evaluate *CO binding strength. This work highlights the critical role of partial oxygen coordination in DACs for C1 hydrocarbons production and proposes a robust descriptor to guide the design of related catalysts.