Ampere-level CO2 electroreduction to multi-carbon oxygenates in acidic electrolyte through surface microenvironment reconstruction

Efficient CO2 electroreduction to multi-carbon (C2+) oxygenates in acidic electrolytes remains a great challenge, especially under high current density conditions. In this study, we prepare an ionic liquid (IL)-modified Cu electrode (IL@Cu), which achieve a Faradaic efficiency (FE) of 82.7% toward C2+ products at a current density of 2.0 A cm−2 in 0.5 M K2SO4 (pH = 1, adjusted with H2SO4), with a single-pass carbon efficiency reaching 78.5%. Under the same conditions, the partial current density for C2+ oxygenates and ethanol exceed 1.2 A cm−2 and 1.0 A cm−2, respectively, over IL@Cu. Mechanism study has shown that K+ cations are repelled by the IL cations during the reaction, allowing water molecules to access the electrode surface. The displacement of K+ enhances C–C coupling, while the proximity of water to the electrode surface facilitates the incorporation of oxygen-containing intermediates into the hydrogen bond network, thereby promoting the formation of C2+ oxygenates. The electroreduction of CO2 to C2+ oxygenates at industrial current density in acidic media is highly significant yet remains a challenge. Here, the authors report an ionic liquid-modified Cu electrode that enables efficient and stable production of C2+ oxygenates at ampere-level current densities.