Tuning the Electrocatalytic Performance of Ionic Liquid Modified Pt Catalysts for the Oxygen Reduction Reaction via Cationic Chain Engineering

Zhang GR, Wolker T, Sandbeck DJS, Munoz M, Mayrhofer K, Cherevko S, Etzold BJ (2018)

Publication Status: Published

Publication Type: Journal article

Publication year: 2018

Journal

ACS Catalysis American Chemical Society

Publisher: AMER CHEMICAL SOC

Book Volume: 8

Pages Range: 8244-8254

Journal Issue: 9

DOI: 10.1021/acscatal.8b02018

Abstract

Modifying Pt catalysts using hydrophobic ionic liquids (ILs) has been demonstrated to be a facile approach for boosting the performance of Pt catalysts for the oxygen reduction reaction (ORR). This work aims to deepen the understanding and initiate a rational molecular tuning of ILs for improved activity and stability. To this end, Pt/C catalysts were modified using a variety of 1-methyl-3-alkylimidazolium bis(trifluoromethanesulfonyl)imide ([C(n)C(1)im][NTf2], n = 2-10) ILs with varying alkyl chain lengths in imidazolium cations, and the electrocatalytic properties (e.g., electrochemically active surface area, catalytic activity, and stability) of the resultant catalysts were systematically investigated. We found that ILs with long cationic chains (C6, C10) efficiently suppressed the formation of nonreactive oxygenated species on Pt; however, at the same time they blocked active Pt sites and led to a lower electrochemically active surface area. It is also disclosed that the catalytic activity strongly correlates with the alkyl chain length of cations, and a distinct dependence of intrinsic activity on the alkyl chain length was identified, with the maximum activity obtained on Pt/C-[C(4)C(1)im][NTf2]. The optimum arises from the counterbalance between more efficient suppression of oxygenated species formation on Pt surfaces and more severe passivation of Pt surfaces with elongation of the alkyl chain length in imidazolium cations. Moreover, the presence of an IL can also improve the electrochemical stability of Pt catalysts by suppressing the Pt dissolution, as revealed by combined identical-location transmission electron microscopy (TEM) and in situ inductively coupled plasma mass spectrometry (ICP-MS) analyses.

Authors with CRIS profile

Karl Mayrhofer Lehrstuhl für Elektrokatalyse (HIERN) Bastian Etzold

Involved external institutions

Forschungszentrum Jülich / Research Centre Jülich (FZJ) DE Germany (DE) Technische Universität Darmstadt DE Germany (DE) Universidad Autónoma de Madrid (UAM) ES Spain (ES)

How to cite

APA:

Zhang, G.-R., Wolker, T., Sandbeck, D.J.S., Munoz, M., Mayrhofer, K., Cherevko, S., & Etzold, B.J. (2018). Tuning the Electrocatalytic Performance of Ionic Liquid Modified Pt Catalysts for the Oxygen Reduction Reaction via Cationic Chain Engineering. ACS Catalysis, 8(9), 8244-8254. https://dx.doi.org/10.1021/acscatal.8b02018

MLA:

Zhang, Gui-Rong, et al. "Tuning the Electrocatalytic Performance of Ionic Liquid Modified Pt Catalysts for the Oxygen Reduction Reaction via Cationic Chain Engineering." ACS Catalysis 8.9 (2018): 8244-8254.

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