Introduction . Single-atom catalysts (SACs), as emerging catalysts with unique central metal chemical environment and high central metal utilization, have shown great potential in both thermal and electrochemical catalysis1 , 2 , 3 , 4 , 5. Particularly, the SACs show high potential in the electrochemical CO 2 reduction reaction (CO 2 RR), which is considered an appealing way to regulate atmospheric CO 2 concentrations6 , 7 , 8 , 9. By using the SACs, high...