The electrocatalytic reduction of CO₂ (CO2RR) into value-added chemicals represents a promising strategy for achieving carbon-neutral energy conversion. However, it is fundamentally limited by sluggish reaction kinetics, insufficient product selectivity, and the competitive hydrogen evolution reaction (HER). Herein, density functional theory (DFT) calculations were employed to systematically investigate transition-metal single-atom catalysts anchored on boron and nitrogen co-doped graphene (TM@BNG), with the aim of elucidating the role of heteroatom-induced coordination engineering in modulating catalytic performance. The results demonstrate that B, N co-doping effectively tailors the electronic structure of the metal active sites, thereby optimizing the adsorption energetics of key intermediates and dictating the reaction pathways. Among the 27 candidates examined, Pd@BNG, Ag@BNG, Sc@BNG, Cu@BNG, Co@BNG, Cd@BNG, and Y@BNG exhibit superior catalytic activity and selectivity toward CO or HCOOH production, featuring low limiting potentials down to −0.06 V while simultaneously suppressing HER. Mechanistic analysis reveals that product selectivity is governed by the relative stabilization of *COOH and *HCOO intermediates during the initial proton-coupled electron transfer step. Furthermore, a physically interpretable descriptor (φ), constructed via machine-learning approaches based on intrinsic electronic properties, establishes a volcano-type correlation with the limiting potential, thereby enabling quantitative prediction of catalytic activity. Collectively, these findings elucidate the electronic-structure modulation of single-atom catalysts and establish a generalizable framework for the rational design of high-performance CO₂RR electrocatalysts.

The electrocatalytic reduction of CO₂ (CO₂RR) into value-added chemicals represents a promising strategy for achieving carbon-neutral energy conversion. However, it is fundamentally limited by sluggish reaction kinetics, insufficient product selectivity, and the competitive hydrogen evolution reaction (HER). Herein, density functional theory (DFT) calculations were employed to systematically investigate transition-metal single-atom catalysts anchored on boron and nitrogen co-doped graphene (TM@BNG), with the aim of elucidating the role of heteroatom-induced coordination engineering in modulating catalytic performance. The results demonstrate that B, N co-doping effectively tailors the electronic structure of the metal active sites, thereby optimizing the adsorption energetics of key intermediates and dictating the reaction pathways. Among the 27 candidates examined, Pd@BNG, Ag@BNG, Sc@BNG, Cu@BNG, Co@BNG, Cd@BNG, and Y@BNG exhibit superior catalytic activity and selectivity toward CO or HCOOH production, featuring low limiting potentials down to −0.06 V while simultaneously suppressing HER. Mechanistic analysis reveals that product selectivity is governed by the relative stabilization of *COOH and *HCOO intermediates during the initial proton-coupled electron transfer step. Furthermore, a physically interpretable descriptor (φ), derived from intrinsic electronic properties using machine-learning approaches, establishes a volcano-type correlation with the limiting potential and provides an effective activity-screening criterion within the investigated TM@BNG dataset. Collectively, these findings clarify the electronic-structure modulation of TM@BNG single-atom catalysts and provide a system-specific framework for screening related B/N-coordinated CO₂RR electrocatalysts.