IV-SFG studies on the effect of Li<SUP>+</SUP> in extending the electrochemical window at the Pt|[C2mim][FSA] interface

초록

The effect of Li+ addition at the interface of a 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide ([C(2)mim][FSA]) room-temperature ionic liquid (RTIL) and a Pt electrode is investigated by infrared-visible sum-frequency generation (IV-SFG) vibrational spectroscopy. Addition of Li+ to the Pt vertical bar[C(2)mim1[FSA] system results in the extension of the electrochemical window (EW) by >1.0 Vat its negative edge. The potential dependence of the SF signal reveals that the [FSA](-) anion of neat [C2mim][FSAI is desorbed at 1.5 V while it remains in place even at 2.0 V when Li+ is added. The SFG spectra indicate that the [FSA](-) anion at the Pt vertical bar[C(2)mim][FSA] interface interacts with Li+ at the interface with the negatively-charged Pt electrode. This [FSA](-) anion layer anchored through Li+ suppresses [C(2)mirr](+) cation adsorption on the negatively-charged Pt electrode, resulting in a wider electrochemical window. (C) 2016 Elsevier B.V. All rights reserved.

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