Functional Group Engineering of Single-Walled Carbon Nanotubes for Anchoring Copper Nanoparticles Toward Selective CO2 Electroreduction to C2 Products.

Electroreduction of carbon dioxide (CO2) is a key strategy for achieving net-zero carbon emissions. Copper (Cu)-based electrocatalysts have shown promise for CO2 conversion into valuable chemicals but are hindered by limited C2+ product selectivity due to competing hydrogen evolution and ineffective dimerization of adsorbed CO intermediate (*CO). Here, a functional-group-directed strategy is reported to enhance selectivity using single-walled carbon nanotubes (SWCNTs) as supports. The catalytic performance of Cu nanoparticles is strongly influenced by the type and density of functional groups on the SWCNTs. Optimized Cu/amine-functionalized SWCNTs achieved a Faradaic efficiency of 66.2% and a partial current density of -270 mA cm-2 for C2 products within a flow cell, outperforming Cu/SWCNTs and Cu/cyano-functionalized SWCNTs. Density functional theory calculations revealed that the electron-donating amine groups can facilitate electron transfer from the graphite sheet to Cu atoms, thereby shifting the d-band center of Cu upward. This shift enhances *CO and its hydrogenation derivative adsorption and promotes water splitting, leading to an increased tendency for the generation of C2 products. In situ infrared and Raman spectroscopy confirm the enhancement of key *CHO intermediate coverage, facilitating C─C coupling. This work provides a molecular framework for exploring interactions between functional groups and active metals in CO2 electrolysis, offering insights for designing catalysts for a broad range of electrocatalytic processes.