Electrochemical CO₂-to-ethylene conversion on polyamine-incorporated Cu electrodes

Electrochemical conversion of CO₂ into value-added chemicals holds promise to enable the transition to carbon neutrality. Enhancing selectivity for a specific hydrocarbon product is challenging, however, due to numerous possible reaction pathways of CO₂ electroreduction. Here we present a Cu–polyamine hybrid catalyst, developed through co-electroplating, that significantly increases the selectivity for ethylene production. The Faradaic efficiency for ethylene production is 87% ± 3% at −0.47 V versus reversible hydrogen electrode, with full-cell energetic efficiency reaching 50% ± 2%. Raman measurements indicate that the polyamine entrained on the Cu electrode results in higher surface pH, higher CO content and higher stabilization of intermediates compared with entrainment of additives containing little or no amine functionality. More broadly, this work shows that polymer incorporation can alter surface reactivity and lead to enhanced product selectivity at high current densities. [Figure not available: see fulltext.]