Enhanced CO₂ Adsorption and Conversion in Diethanolamine-Cu Interfaces Achieving Stable Neutral Ethylene Electrosynthesis

Molecular modifications have shown tremendous potential in boosting the electrochemical CO₂ reduction (CO₂RR) to ethylene. However, the key mechanisms of modulation at the molecular level remain unclear, especially for the adsorption and activation of key intermediates (e.g., ^*CO₂ and ^*CO). Here, report that a diethanolamine (DEA)-modified Cu catalyst can reduce CO₂ to ethylene with a faradaic efficiency of ≈50.5% with a partial current density of ≈155.7 mA cm⁻² in the neutral conditions, which surpasses the Cu catalyst without molecular modification (≈28.5% and ≈95.6 mA cm⁻²). Density functional theory calculations demonstrate that DEA on the Cu surface boosts the adsorption and activation of CO₂ and the following C–C coupling processes during the CO₂RR-to-ethylene process. Molecular dynamics simulations suggest that the molecules distant from the Cu site have a CO₂ enrichment effect. Operational stability achieved via the introduction of DEA molecules onto ketjen black, which then successively immobilized on the Cu nanoparticles and polytetrafluoroethylene electrodes to obtain a stable tripe-phase boundary, realizing constant ethylene selectivity for 100 operating hours in a flow cell.