The Electrochemical Behaviour of Quaternary Amine-Based Room-Temperature Ionic Liquid N4111(TFSI)

In this study, we used the in situ X-ray photoelectron spectroscopy (XPS), in situ mass spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy methods, for the first time, in a detailed exploration of the electrochemical behaviour of a quaternary amine cation-based room-temperature ionic liquid, butyl-trimethyl-ammonium bis(trifluoromethylsulfonyl)imide (N4111(TFSI)), at the negatively and positively polarised molybdenum carbide-derived micro-mesoporous carbon (mmp-C(Mo2C)) electrodes that can be used as high surface area supporting material for electrocatalysts. The shapes of the C 1s, N 1s, O 1s, F 1s and S 2p XPS spectra were stable for N4111(TFSI) within a very wide potential range. The XPS data indicated the non-specific adsorption character of the cations and anions in the potential range from -2.00 V to 0.00 V. Thus, this region can be used for the detailed analysis of catalytic reaction mechanisms. We observed strong adsorption from 0.00 V to 1.80 V, and at E > 1.80 V, very strong adsorption of the N4111(TFSI) at the mmp-C(Mo2C) took place. At more negative potentials than -2.00 V, the formation of a surface layer containing both N4111(+) cations and TFSI- anions was established with the formation of various gaseous compounds. Collected data indicated the electrochemical instability of the N4111(+) cation at E < -2.00 V.

Automated summary

The study utilized in situ X-ray photoelectron spectroscopy (XPS), in situ mass spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy methods to explore the electrochemical behavior of a quaternary amine cation-based room-temperature ionic liquid at molybdenum carbide-derived micro-mesoporous carbon electrodes. The XPS data showed stable spectra within a wide potential range and indicated non-specific adsorption of cations and anions for analysis of catalytic reaction mechanisms. Strong adsorption was observed at certain potentials and electrochemical instability of the cation was found at more negative potentials.