Electroreduction of diluted CO to multicarbon products with high carbon utilization at 800 mA cm in strongly acidic media.

Acidic CO electroreduction using diluted CO (as in flue gas) as the feedstock can simultaneously circumvent the CO purification step and lower the carbon loss in conventional alkaline or neutral electrolyte, and thus is highly desired but has rarely been achieved thus far. Herein, we report a simple and general strategy using an imidazolium-based anion-exchange ionomer as the coating layer, which could enrich the diluted CO to generate a high local CO concentration, and simultaneously block the proton transport to the cathode surface to suppress the competing hydrogen evolution reaction. As a result, the ionomer-modified Cu catalyst can achieve an efficient electroreduction of diluted CO (15 vol% CO) to multicarbon (C) products in strong acid (pH 0.8), with a high C Faradaic efficiency of 70.5% and a high single-pass carbon efficiency of 73.6% at a current density of 800 mA cm, competitive with that obtained with pure CO. These findings provide opportunity for the direct electrochemical conversion of flue gas into valuable products with high efficiency.