Highly selective and low-overpotential electrocatalytic CO2 reduction to ethanol by Cu-single atoms decorated N-doped carbon dots

Selective, low-overpotential and high Faradaic efficiency electroreduction of CO2 to ethanol is in prominent global demand and lies in structuring, loading, and modulating the coordination states of Cu single atom catalysts (SACs) with support matrix. Here, the low-temperature (160 °C) synthesis of Cu–SACs–N-doped carbons dots (Cu–SACs–N–CQDs) is reported via Cu–dopamine complex process. The optimized Cu–SACs–N–CQDs electrocatalyst brings remarkably high Faraday efficiency (> 80%) and selectivity for ethanol with 50 h operation stability, which far exceeds previous results in terms of overpotential, stability, and Faraday efficiency. Surprisingly, the Faraday efficiency and selectivity of ethanol are highly sensitive to the coordination states of copper SACs with variation of Cu loadings. Operando X-ray absorption spectroscopy indicates in situ-generated neighboring metallic Cu–Cu atom coordination as real catalytic active sites from isolated single Cu atom during CO2 reduction, which favors the ethanol selectivity.