Efficiently electrochemical CO2 reduction on molybdenum-nitrogen-carbon catalysts with optimized p-block axial ligands.

The p-block elements are evaluated as axial ligands of single-atom Mo for highly efficient two-electron CO 2 reduction reaction. [Display omitted] • Single-atom Mo modified by 20 p-block elements as axial ligands was studied by first-principles calculation. • The axial ligand had a significant effect on adsorption strength of Mo atom for CO 2 RR intermediates. • Ge-MoN 4 exhibited the best performance in the two-electron CO 2 RR. • The CO 2 RR activity was related to the inherent properties of the axial ligands. Inspired by the structure of molybdenum-based metalloenzymes with high CO 2 conversion efficiency in nature, the catalytic performance of a series of modified MoN 4 for two-electron CO 2 reduction reaction (CO 2 RR) was systematically studied using first-principles calculations. The effect of 20 p-block elements as axial ligands on the structure of MoN 4 was evaluated. Benefiting from the significant effect of the axial ligands on the adsorption strength of Mo for intermediates, both activity and selectivity were improved, especially Ge-MoN 4 exhibited the best performance in the formic acid (HCOOH) pathway. The orbital hybridization between Mo and the intermediate was weakened to varying degrees by axial ligands. Furthermore, the activity of the catalysts was related to the properties of the axial ligands, especially the Mo-N bond length and the electronegativity difference between Mo and the axial ligands. This work provides a thorough understanding and guidance for modifying the coordination environment of single-atom catalysts for CO 2 RR. [ABSTRACT FROM AUTHOR]