Copper is particularly interesting for CO2 electroreduction (both in aqueous and organic media) due to its unique ability to produce a significant amount of hydrocarbons. Recently it has been shown that Cu electrode is selective to make CO in acetonitrile (non-aqueous media) . Yet CO2 reduction occurred at high overpotentials.
For CO2 reduction, in a first stage, one electron should be transferred to CO2 to form CO2 radical (CO2-) . This intermediate is very unstable and requires high activation energy which in turn results in sluggish kinetics for overall reaction. Room temperature ionic liquids (molten salts) have been shown to mitigate these problems with co-catalytic effects [3,4]. Inspired by this, in this master assignment ionic liquids are investigated for their co-catalytic effects for CO2 reduction at Cu electrode. Cations of different acidities in combination with a weakly coordinating base will be systematically studied.
This will be done first in dry acetonitrile at different concentrations of ionic liquids, then the promoting effect of adding water will be considered. Voltammetry methods, gas analysis (with GC and MS spectroscopy), liquid analysis (H, C and F NMR) and HPLC are tools to be used for this assignment. In situ spectroscopy methods can be applied to understand the immediate effects of ionic liquids at the electrode interface.
1- Marta C. Figueiredo, " In Situ Spectroscopic Study of CO2 Electroreduction at Copper Electrodes in Acetonitrile'', ACS Catal, , 6, 2382−2392. (2016)
2- Y.Hori, "Electrochemical CO2 Reduction on Metal Electrodes", in Modern aspects of electrochemistry, By Constantinos.G. Vayenas. No: 42, 89-189
3- Brian A. Rosen, et al, "Ionic Liquid–Mediated Selective Conversion of CO2 to CO at Low Overpotentials", Science, 334, 643-644. (2011)
4- H. Lim and H. Kim, "The Mechanism of Room-Temperature Ionic-Liquid-Based Electrochemical CO2 Reduction: A Review", Molecules, 22, 536. (2017)