Structure and Stability of the Ionic Liquid Clusters [EMIM]n[BF4]n+1-(n = 1-9): Implications for Electrochemical Separations

Jun Zhang, Eric T. Baxter, Manh Thuong Nguyen, Venkateshkumar Prabhakaran, Roger Rousseau, Grant E. Johnson, Vassiliki Alexandra Glezakou

Research output: Contribution to journalArticle

Abstract

Precise functionalization of electrodes with size-selected ionic liquid (IL) clusters may improve the application of ILs in electrochemical separations. Herein we report our combined experimental and theoretical investigation of the IL clusters 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM]n[BF4]n+1- (n = 1-9) and demonstrate their selectivity and efficiency toward targeted adsorption of ions from solution. The structures and energies of the IL clusters, predicted with global optimization, agree with and help interpret the ion abundances and stabilities measured by high-mass-resolution electrospray ionization mass spectrometry and collision-induced dissociation experiments. The [EMIM][BF4]2- cluster, which was identified as the most stable IL cluster, was selectively soft-landed onto a working electrode. Electrochemical impedance spectroscopy revealed a lower charge transfer resistance on the soft-landed electrode containing [EMIM][BF4]2- compared with an electrode prepared by drop-casting of an IL solution containing the full range of IL clusters. Our findings indicate that specific IL clusters may be used to increase the efficiency of electrochemical separations by lowering the overpotentials involved.

Original languageEnglish
Pages (from-to)6844-6851
Number of pages8
JournalJournal of Physical Chemistry Letters
Volume11
Issue number16
DOIs
Publication statusPublished - Aug 20 2020

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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