Activating dynamic atomic-configuration for single-site electrocatalyst in electrochemical CO₂ reduction

One challenge for realizing high-efficiency electrocatalysts for CO₂ electroreduction is lacking in comprehensive understanding of potential-driven chemical state and dynamic atomic-configuration evolutions. Herein, by using a complementary combination of in situ/operando methods and employing copper single-atom electrocatalyst as a model system, we provide evidence on how the complex interplay among dynamic atomic-configuration, chemical state change and surface coulombic charging determines the resulting product profiles. We further demonstrate an informative indicator of atomic surface charge (φ_e) for evaluating the CO₂RR performance, and validate potential-driven dynamic low-coordinated Cu centers for performing significantly high selectivity and activity toward CO product over the well-known four N-coordinated counterparts. It indicates that the structural reconstruction only involved the dynamic breaking of Cu-N bond is partially reversible, whereas Cu-Cu bond formation is clearly irreversible. For all single-atom electrocatalysts (Cu, Fe and Co), the φ_e value for efficient CO production has been revealed closely correlated with the configuration transformation to generate dynamic low-coordinated configuration. A universal explication can be concluded that the dynamic low-coordinated configuration is the active form to efficiently catalyze CO₂-to-CO conversion.