Modulating the Asymmetric Atomic Interface of Copper Single Atoms for Efficient CO 2 Electroreduction.

Cu single-atom catalysts (Cu SACs) have been considered as promising catalysts for efficient electrocatalytic CO reduction reactions (ECRRs). However, the reports on Cu SACs with an asymmetric atomic interface to obtain CO are few. Herein, we rationally designed two Cu SACs with different asymmetric atomic interfaces to explore their catalytic performance. The catalyst of CuNO/C delivers high ECRR selectivity with an FE value of above 90% in a wide potential window from -0.5 to -0.9 V vs RHE (in particular, 96% at -0.8 V), while CuCO/C delivers poor selectivity for CO production with a maximum FE value of only 20.0% at -0.5 V vs RHE. Besides, CuNO/C exhibited a large turnover frequency (TOF) up to 2782.6 h at -0.9 V vs RHE, which is much better than the maximum 4.8 h of CuCO/C. Density functional theory (DFT) results demonstrate that the CuNO site needs a lower Gibbs free energy than CuCO in the rate-determining step of CO desorption, leading to the outstanding performance of CuNO/C on the process of ECRR-to-CO. This work provides an efficient strategy to improve the selectivity and activity of the ECRR via regulating asymmetric atomic interfaces of SACs by adjusting the coordination atoms.