The role of adsorbed ions during electrocatalysis in ionic liquids

Ejigu, Andinet; Walsh, Darren A.

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.

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. https://doi.org/10.1021/jp411730z

• Journal Article Type: Article
• Acceptance Date: Mar 12, 2014
• Online Publication Date: Mar 12, 2014
• Publication Date: Apr 10, 2014
• Deposit Date: Oct 23, 2018
• Publicly Available Date: Oct 23, 2018
• 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
• DOI: https://doi.org/10.1021/jp411730z
• Keywords: ionic liquid; CO displacement; electrocatalysis; potential of zero charge; ion adsorption
• Public URL: https://nottingham-repository.worktribe.com/output/1182984
• Publisher URL: https://pubs.acs.org/doi/abs/10.1021/jp411730z