Local Coordination Environment-Driven Structural Dynamics of Single-Atom Copper and the CO₂ Electroreduction Pathway

Structural stability is a critical factor in realizing the potential of single-atom catalysts (SACs), yet remaining a major challenge hindering their large-scale application. Understanding the operando structural dynamics of SACs is essential for elucidating the structure-activity relationship and guiding the design of high-performance SACs. In this study, we selected five well-defined mononuclear copper (Cu) complexes with varying ligand structures to explore the coordination-driven structural dynamics of Cu single atoms and their interaction with the electrochemical CO₂ reduction (CO₂R) pathway. Coordination environments strongly influence the reconfiguration behaviors of Cu SACs by affecting the binding energy and charge distribution between Cu and the ligands. The in situ reconstructed Cu(0) and Cu(I) sites act as active centers for carbon product formation. Specifically, Cu(0) is closely associated with CH₄ generation, while a unique Cu(I)N₃H-*CO intermediate promotes multicarbon production by acting as a bridge, transferring *CO to neighboring Cu(0) with abundant unsaturated sites. This work highlights the impact of coordination environments on product distribution by influencing the reconfiguration behaviors of SACs and provides theoretical insights for designing Cu SACs with enhanced stability and tailored CO₂R product selectivity.