Cu single-atom catalysts (Cu SACs) have been considered as promising catalysts for efficient electrocatalytic CO2 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 CuN3O/C delivers high ECRR selectivity with an FECO 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 CuCO3/C delivers poor selectivity for CO production with a maximum FECO value of only 20.0% at -0.5 V vs RHE. Besides, CuN3O/C exhibited a large turnover frequency (TOF) up to 2782.6 h-1 at -0.9 V vs RHE, which is much better than the maximum 4.8 h-1 of CuCO3/C. Density functional theory (DFT) results demonstrate that the CuN3O site needs a lower Gibbs free energy than CuCO3 in the rate-determining step of CO desorption, leading to the outstanding performance of CuN3O/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.
Keywords: CO2 electroreduction; asymmetric atomic interface; copper single atoms; high CO Faradaic efficiency; large turnover frequency.