CO<sub>2</sub> electroreduction to ethylene via hydroxide-mediated copper catalysis at an abrupt interface.

Dinh, Cao-Thang; Burdyny, Thomas; Kibria, Md Golam; Seifitokaldani, Ali; Gabardo, Christine M; García de Arquer, F Pelayo; Kiani, Amirreza; Edwards, Jonathan P et al. · Science · 2018

basic_science · Level V

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Abstract

Carbon dioxide (CO<sub>2</sub>) electroreduction could provide a useful source of ethylene, but low conversion efficiency, low production rates, and low catalyst stability limit current systems. Here we report that a copper electrocatalyst at an abrupt reaction interface in an alkaline electrolyte reduces CO<sub>2</sub> to ethylene with 70% faradaic efficiency at a potential of -0.55 volts versus a reversible hydrogen electrode (RHE). Hydroxide ions on or near the copper surface lower the CO<sub>2</sub> reduction and carbon monoxide (CO)-CO coupling activation energy barriers; as a result, onset of ethylene evolution at -0.165 volts versus an RHE in 10 molar potassium hydroxide occurs almost simultaneously with CO production. Operational stability was enhanced via the introduction of a polymer-based gas diffusion layer that sandwiches the reaction interface between separate hydrophobic and conductive supports, providing constant ethylene selectivity for an initial 150 operating hours.