On-Surface Modification of Copper Cathodes by Copper(I)-Catalyzed Azide Alkyne Cycloaddition and CO₂ Reduction in...

In this study, organic structures were introduced onto copper cathodes to induce changes in their electrocatalytic CO₂ reduction activity. Poorly soluble organic polymers were distributed onto the copper surface as a thin layer by polymerizing monomeric precursors via a copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) activated by anodization of the copper substrate. The resulting structure possesses copper surface atoms that are available to participate in the CO₂ reduction reaction-comparable to close-contact organic structures-and stabilize the adsorption of organic layers through the CO₂ reduction process. The CO₂ reduction performance of the on-surface modified copper cathode exhibited improved CO₂ reduction over H₂ evolution compared with traditional cast modification systems. Preventing organic moieties from forming densely packed assemblies on the metal surface appears to be important to promote the CO₂ reduction process on the copper atoms. The suppression of H₂ evolution, a high methane/ethylene ratio, and the influence of stirring demonstrate that the improved CO₂ reduction activity is not only a result of the copper atom reorganization accompanied by repeating anodization for modification; the organic layer also apparently plays an important role in proton transfer and CO₂ accumulation onto the copper surface.