Ionic Liquid-Modified Electrocatalysts: The Interaction of [C1C2Im][OTf] with Pt(1 1 1) and its Influence on Methanol Oxidation Studied by Electrochemical IR Spectroscopy

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Details zur Publikation

Autor(en): Brummel O, Faisal F, Bauer T, Pohako-Esko K, Wasserscheid P, Libuda J
Zeitschrift: Electrochimica Acta
Verlag: Elsevier
Jahr der Veröffentlichung: 2016
Band: 188
Seitenbereich: 825-836
ISSN: 0013-4686


Abstract


Ionic liquids (ILs) have recently been proposed as modifying agents to tune the selectivity and the activity of electrocatalysts. In order to explore the origin of IL-induced effects on electrocatalytic reactions, we have investigated (i) the interaction of [CCIm][OTf]-water mixtures with Pt(1 1 1) single crystal electrodes and (ii) the influence of [CCIm][OTf] on methanol oxidation in acidic aqueous solution using cyclic voltammetry (CV) and electrochemical IR spectroscopy. We show that [CCIm][OTf] interacts strongly with the Pt(1 1 1) surface in the potential range from -0.2 V to 0.65 V, leading to partial blocking of the surface, partial suppression of hydrogen adsorption, and partial suppression of OH formation. The interaction of the IL with Pt occurs in this potential range via specific adsorption of the [OTf] anions which bind to Pt(1 1 1) via the SO group in a tilted adsorption geometry. The adsorption process is largely reversible as a function of the electrode potential, but shows a complex kinetics and becomes very slow at high IL coverage. Also, [CCIm][OTf] has a strong effect on the electro-oxidation of methanol in acidic solution. Adsorption of [OTf] leads to partial blocking of the indirect oxidation pathway to CO. The onset potential for CO oxidation is found to be shifted to more positive values indicating hindered access of HO to the electrode surface. CO and the [CCIm][OTf] form a mixed co-adsorption layer which is characterized by a strongly red-shifted CO stretching band. The effect is assigned to an IL-induced ligand effect in the mixed adsorbate layer and suggests that the direct modification of active centers by surface-bound IL species plays an important role in IL-modified electrocatalytic materials.



FAU-Autoren / FAU-Herausgeber

Bauer, Tanja
Professur für Physikalische Chemie
Brummel, Olaf Dr.
Professur für Physikalische Chemie
Faisal, Firas
Professur für Physikalische Chemie
Libuda, Jörg Prof. Dr.
Professur für Physikalische Chemie
Pohako-Esko, Kaija
Lehrstuhl für Chemische Reaktionstechnik
Wasserscheid, Peter Prof. Dr.
Lehrstuhl für Chemische Reaktionstechnik


Zusätzliche Organisationseinheit(en)
Exzellenz-Cluster Engineering of Advanced Materials


Zitierweisen

APA:
Brummel, O., Faisal, F., Bauer, T., Pohako-Esko, K., Wasserscheid, P., & Libuda, J. (2016). Ionic Liquid-Modified Electrocatalysts: The Interaction of [C1C2Im][OTf] with Pt(1 1 1) and its Influence on Methanol Oxidation Studied by Electrochemical IR Spectroscopy. Electrochimica Acta, 188, 825-836. https://dx.doi.org/10.1016/j.electacta.2015.12.006

MLA:
Brummel, Olaf, et al. "Ionic Liquid-Modified Electrocatalysts: The Interaction of [C1C2Im][OTf] with Pt(1 1 1) and its Influence on Methanol Oxidation Studied by Electrochemical IR Spectroscopy." Electrochimica Acta 188 (2016): 825-836.

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