Abstract
The reasonable design of low-cost, high-activity single-atom catalysts (SACs) is crucial for achieving highly efficient electrochemical CO(2)RR. In this study, we systematically explore, using density functional theory (DFT), the performance of transition metal (TM = Mn, Fe, Co, Ni, Cu, Zn)-doped defect-type hexagonal boron nitride (h-BN) SACs TM@B(-1)N (B vacancy) and TM@BN(-1) (N vacancy) in both CO(2)RR and the hydrogen evolution reaction (HER). Integrated crystal orbital Hamiltonian population (ICOHP) analysis reveals that these catalysts weaken the sp orbital hybridization of CO(2), which promotes the formation of radical-state intermediates and significantly reduces the energy barrier for the hydrogenation reaction. Therefore, these theoretical calculations indicate that the Mn, Fe, Co@B(-1)N, and Co@BN(-1) systems demonstrate excellent CO(2) chemical adsorption properties. In the CO(2)RR pathway, Mn@B(-1)N exhibits the lowest limiting potential (U(L) = -0.524 V), and its higher d-band center (-0.334 eV), which aligns optimally with the adsorbate orbitals, highlights its excellent catalytic activity. Notably, Co@BN(-1) exhibits the highest activity in HER, while U(L) is -0.217 V. Furthermore, comparative analysis reveals that Mn@B(-1)N shows 16.4 times higher selectivity for CO(2)RR than for HER. This study provides a theoretical framework for designing bifunctional SACs with selective reaction pathways. Mn@B(-1)N shows considerable potential for selective CO(2) conversion, while Co@BN(-1) demonstrates promising prospects for efficient hydrogen production.