Interaction of Aluminum and Platinum Surfaces with the Ionic Liquids 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Abstract

The processes at the interface between ionic liquids (ILs) and metals are a key factor for understanding especially in electrochemical deposition, nanoscale tribology applications and batteries. In the present work, the interfaces of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Py1,4]TFSI) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm]TFSI) and platinum and aluminum were investigated by depositing thin IL films and studying them with X-ray photoelectron spectroscopy (XPS) in ultrahigh vacuum. It is found that there is no evidence of a decomposition reaction of either IL on platinum; however, the imidazolium cation of [EMIm]TFSI shows a strong interaction with the surface in the monolayer regime. In contrast, [Py1,4]TFSI and [EMIm]TFSI show massive decomposition on the aluminum surface without applying any electrochemical potential. The spectra for the [TFSI]− anion components show cleavage of C-F or N-S bonds in both cases. Both cleavage of a single fluorine atom and complete cleavage were observed, leading to further decomposition reactions of the anion. Consequently, new components such as AlOOH, Al(OH)3, Al2S3, Al2(SO4)3 and AlF3 appear at the interface. In addition, there is also evidence of decomposition of the cation by the splitting off hydrogen atoms or parts of the alkyl chain in both ILs.

Optical Modification of a Nanoporous Alumina Structure Associated with Surface Coverage by the Ionic Liquid AliquatCl

“…In particular, ILs such as trioctylmethylammonium chloride (or AliquatCl) and its derivatives (trioctylmethylammonium nitrate or trioctylmethylammonium thiocianate) are being used in the fabrication of polymer inclusion membranes (PIMs) for the removal of pollutants from natural waters (small organic molecules or metallic species), acting as extractants or carriers, but also improving the mechanical stability of PIMs [ 39 , 40 , 41 , 42 , 43 , 44 ]; other ILs have been incorporated into the structure of Nafion membranes for the reduction in gas and methanol crossover or to improve the membrane stability at a temperature higher than 80 °C [ 45 , 46 , 47 , 48 , 49 ]. Due to the particular characteristics of ILs when compared to conventional electrolytes, they are also used for electrochemical devices (batteries, capacitors, or fuel cells), electrodeposition, catalysis, renewable energy generation, and storage processes [ 50 , 51 , 52 , 53 , 54 , 55 ]. Moreover, ILs have lately begun to be considered as novel electrolytes in different types of solar cells (dye-sensitized solar cells, polymer solar cells, or thin film solar cells) [ 56 , 57 , 58 , 59 ].…”