Promoting Electrocatalytic Carbon Monoxide Reduction to Ethylene on Copper-Polypyrrole Interface

Abstract The renewable energy-powered electroreduction of carbon dioxide or monoxide (CO) has been emerging as an attractive means to decarbonize the emission-intensive chemical manufacturing, which heavily relies on fossil fuels nowadays. One potential approach to promote the activity of electrocatalysts is to construct hybrid interface that can increase the stability of intermediates on electrode surfaces. Herein we developed a copper nanoparticle/polypyrrole (Cu-Ppy) nanowire composite as an efficient electrocatalyst for electrochemical CO reduction reaction. Compared to pure Cu nanoparticles, the Cu-Ppy composite exhibited a dramatically enhanced Faradaic efficiency of converting CO to ethylene (C2H4) from 34% to 69% at −0.78 V vs. reversible hydrogen electrode (RHE) in KOH electrolyte, and an excellent C2H4 partial current density of 276 mA·cm-2 at −1.18 V vs. RHE. Density functional theory calculations showed that the Cu-Ppy composite could bind CO more strongly as compared to pure Cu. As the Ppy coating allowed to stabilize OCCO*, a key intermediate in the C2H4 formation, both the activity and selectivity of Cu-Ppy for CO-to-C2H4 were increased. Our work suggests that constructing rationally designed hybrid interface can tune the local environment of catalyst surface toward enhanced activity and product selectivity.