Theoretical insights into the bipyridine-coordinated single atom catalysis on MoS2 for CO2 reduction reaction

• Demonstrating a novel bipyridine (Bpy)-coordinated single transition metal (TM) functionalization strategy for 2D MoS 2 (TM-Bpy/MoS 2 , TM = Mn, Co, Ni, Zn, Cu, Cd). • Uncovering that the N-TM-S bond bridge creates a unique coordination environment enabling strong CO 2 activation. • Completed 8-electron reduction free energy landscape for CO 2 -to-CH 4 on TM-Bpy/MoS 2 elucidates the origin of high CH 4 selectivity through key intermediate stabilization mechanisms. • Providing profound theoretical insights into the reaction mechanisms of CO 2 photoreduction over catalysts featuring functional organic–inorganic hybrid interfaces. Two-dimensional (2D) materials exhibit considerable potential for photocatalytic applications due to their enhanced charge separation efficiency and abundant active sites. In this study, we modify 2D MoS 2 with bipyridine-coordinated single transition metal atom (TM-Bpy/MoS 2 , TM = Mn, Co, Ni, Zn, Cu, and Cd) to systematically investigate their reaction mechanisms for CO 2 reduction to C 1 products using density functional theory calculations. The results demonstrate that the formation of N-TM-S bonds facilitates the injection of photogenerated electrons into the *CO 2 antibonding orbitals, thereby supplying the necessary electrons for the CO 2 RR. Concurrently, this process plays a critical role in enhancing catalytic activity by weakening the adsorption of reactants at the active sites. Free energy calculations delineate a complete 8-electron reduction pathway, while electronic structure analysis uncovers the stabilization of key intermediates. This work elucidates the reaction pathway and the universal origin of CH 4 selectivity in TM-Bpy/MoS 2 catalysts at atomic scale. These theoretical findings provide profound mechanistic insights into the CO 2 reduction processes of catalysts with functional organic groups.