Boosting C–C coupling to multicarbon products via high-pressure CO electroreduction

Electrochemical CO reduction reaction (CORR) provides a promising approach for producing valuable multicarbon products (C2+), while the low solubility of CO in aqueous solution and high energy barrier of C–C coupling as well as the competing hydrogen evolution reaction (HER) largely limit the efficiency for C2+ production in CORR. Here we report an overturn on the Faradaic efficiency of CORR from being HER-dominant to C2+ formation-dominant over a wide potential window, accompanied by a significant activity enhancement over a Moss-like Cu catalyst via pressuring CO. With the CO pressure rising from 1 to 40 atm, the C2+ Faradaic efficiency and partial current density remarkably increase from 22.8% and 18.9 mA cm−2 to 89.7% and 116.7 mA cm−2, respectively. Experimental and theoretical investigations reveal that high pressure-induced high CO coverage on metallic Cu surface weakens the Cu–C bond via reducing electron transfer from Cu to adsorbed CO and restrains hydrogen adsorption, which significantly facilitates the C–C coupling while suppressing HER on the predominant Cu(111) surface, thereby boosting the CO electroreduction to C2+ activity.