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

Abstract

•Organosuperbase-modified Cu promotes CO2 electrocatalysis to multi-carbon products •Organosuperbase modification suppresses carbonate formation challenge •Protonated organosuperbases stabilize CO intermediates on Cu surface •Proton sponge modification presented a 20-fold improvement in C2+ to C1 ratio 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. 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.