Performance of Transition Metals in Imidazolium‐Assisted CO2 Reduction in Acetonitrile

Abstract

Abstract This study explores the electrochemical reduction of CO2 in dry acetonitrile containing 1,3‐dimethyl imidazolium cations, utilizing late‐transition metals (Au, Ag, Zn, Cu, and Ni). All metals exhibit remarkable selectivity, nearing 100 %, for CO formation. Particularly noteworthy is Au, which manifests the lowest (−2.37 V vs. Ag/Ag+) overpotential in chronopotentiometry experiments. We propose that, for metals with lower CO binding energies compared to Au (Ag and Zn electrodes) – calculated by DFT, the rate‐determining step is the adsorption of CO2. This distinction in CO2 adsorption is reinforced by the examination of partial charge transfer from negatively charged slabs to CO2 (−0.241 a.u with the Au electrode and +0.002 a.u with the Zn electrode). Conversely, the greater CO binding energy calculated for Cu and Ni likely diminishes electrocatalytic activity relative to the Au electrode. Our results unveil a volcano trend in catalyst activity, albeit with smaller performance disparities between the late‐transition metals and Au than previously observed in aqueous conditions, possibly due to the co‐catalytic influence of imidazolium cations. This study suggests that metals unsuitable for aqueous environments hold promise for cost‐effective and viable electrochemical conversion of CO2 to CO in non‐aqueous media containing imidazolium compounds.

Keywords

• carbon dioxide
• électrodes
• imidazolium
• acetonitrile
• carbon monoxide