Density functional theory calculation of first-row transition metals anchored on pyridine-based graphynes as single-atom catalysts for electrocatalytic CO2 reduction†

The electrocatalytic reduction of CO₂ to produce chemicals or fuels is widely regarded as an effective strategy for achieving carbon neutrality. Single-atom catalysts have garnered significant attention owing to their exceptional atomic utilization efficiency. In this study, we employed spin-polarized density functional theory to investigate the electrocatalytic reduction of CO₂ on first-row transition metals anchored on pyridine-based graphynes (TM@pdGYs). Analysis of binding energies, cohesion energies and formation energies indicates their high structure stability and synthesis feasibility. The results of electronic structure analysis showed a robust interaction between metal atoms and pdGY, with the forming of stable covalent bonds. Competitive analysis with the hydrogen evolution reaction (HER) indicates superior selectivity for CO₂ reduction over the HER for all the TM@pdGYs. We also constructed Gibbs free energy level diagrams for the production of four C1 products by each catalyst, revealing that CH₄ and HCOOH are the most favorable products. Notably, Cr/Fe/Co/Zn@pdGY exhibits excellent CO₂ reduction performance with low limiting potentials (−0.13 V to −0.38 V), enabling further decrease in ΔG_max under applied external potential, and possibly rendering the reaction completely spontaneous. These findings suggest that TM@pdGYs represent a promising class of electrocatalysts for CO₂ reduction.