Electrochemical CO2 reduction (CO2 ER) is an efficient and clean process to convert CO2 into liquid fuels and other reduced carbon-based compounds . In contrast with conventional commercial methods, such as CO2 hydrogenation or the Fisher-Tropsch processes, CO2 ER can be conducted under ambient temperatures and pressures using modular, scalable and decentralized units . Copper-based catalysts are the most selective materials known to unlock CO2 ER towards C2+ compounds, such as ethanol and ethylene and other multi-carbon hydrocarbons. And compared to other metal catalysts, copper exhibits a relatively lower selectivity towards hydrogen evolution, leading to unmatched Faradaic efficiencies for CO2 ER .