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The role of adsorbed ions during electrocatalysis in ionic liquids

Ejigu, Andinet; Walsh, Darren A.

Authors

Andinet Ejigu



Abstract

The effects of electrode–adsorbate interactions on electrocatalysis at Pt in ionic liquids are described. The ionic liquids are diethylmethylammonium trifluoromethanesulfonate, [dema][TfO], dimethylethylammonium trifluoromethanesulfonate, [dmea][TfO], and diethylmethylammonium bis(trifluoromethanesulfonyl)imide, [dema][Tf2N]. Electrochemical analysis indicates that a monolayer of hydrogen adsorbs onto Pt during potential cycling in [dema][[TfO] and [dmea][TfO]. In addition, a prepeak is observed at lower potentials than that of the main oxidation peak during CO oxidation in the [TfO]−-based liquids. In contrast, hydrogen does not adsorb onto Pt during potential cycling in [dema][Tf2N] and no prepeak is observed during CO oxidation. By displacing adsorbed ions on Pt surfaces with CO at a range of potentials, and measuring the charge passed during ion displacement, the potentials of zero total charge of Pt in [dema][TfO] and [dmea][TfO] were measured as 271 ± 9 and 289 ± 10 mV vs RHE, respectively. CO displacement experiments also indicate that the [Tf2N]− ion is bound to the Pt surface at potentials above −0.2 V and the implications of ion adsorption on electrocatalysis of the CO oxidation reaction and O2 reduction reaction in the protic ionic liquids are discussed.

Journal Article Type Article
Publication Date Apr 10, 2014
Journal The Journal of Physical Chemistry C
Print ISSN 1932-7447
Electronic ISSN 1932-7455
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 118
Issue 14
Pages 7414-7422
APA6 Citation Ejigu, A., & Walsh, D. A. (2014). The role of adsorbed ions during electrocatalysis in ionic liquids. Journal of Physical Chemistry C, 118(14), (7414-7422). doi:10.1021/jp411730z. ISSN 1932-7447
DOI https://doi.org/10.1021/jp411730z
Keywords ionic liquid; CO displacement; electrocatalysis; potential of zero charge; ion adsorption
Publisher URL https://pubs.acs.org/doi/abs/10.1021/jp411730z

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