Proton sponge promotion of electrochemical CO₂ reduction to multi-carbon products

High alkaline electrolytes have shown the potential to promote high-value C₂₊ products in the electrochemical CO₂ reduction reaction (CO₂RR), but the practical application is challenged by their strong CO₂ absorption with the electrolyte to form carbonate. By modifying the Cu catalyst surface with water-insoluble organosuperbases, such as thebis(dimethylamino)naphthalene “proton sponge,” here, we change the interfacial microenvironment to stabilize adsorbed CO through a locally enhanced electrostatic field while maintaining a neutral pH electrolyte. Molecular dynamics (MD) with a reactive force field and density functional theory (DFT) calculations show that the CO intermediate is stabilized on the Cu surface by protonated organosuperbases, which promotes C₂₊ product formation over CO desorption. The organosuperbase-modified commercial Cu nanoparticle presented a 20-fold improvement in C₂₊ to C₁ ratio compared with its pristine performance, delivering a maximal C₂₊ faradic efficiency of ∼80% and large partial current of over 270 mA cm⁻² in neutral electrolyte.