Water Clustering Modulates Activity and Enables Hydrogenated Product Formation during Carbon Monoxide Electroreduction in Aprotic Media

H Fejzic and R Kumar and RJ Gomes and LL He and TJ Houser and J Kim and M Mohebi and N Molten and CV Amanchukwu, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 147, 18445-18459 (2025).

DOI: 10.1021/jacs.4c07865

Water solvation plays a critical role in a wide range of electrochemical transformations, but its role is often convoluted since water is typically used as both a solvent and a proton source. Here, we experimentally control water speciation and activity using aprotic solvent media during the carbon monoxide reduction reaction (CORR). Remarkably, we show that aprotic solvents that support microheterogeneous water-water clusters lead to significant amounts of CORR products (methane and ethylene) with a maximum ethylene Faradaic efficiency of 22% in acetonitrile (chi H2O = 0.2). In contrast, microhomogeneous systems-where water integrates into the solvents' intermolecular binding network and has lower activity-primarily support the undesired hydrogen evolution reaction (HER). Insights gained expand our understanding of water activity and nonaqueous electrolyte design for other important transformation reactions beyond CO reduction, such as CO2RR and HER.

Return to Publications page