The role of adsorbed ions during electrocatalysis in ionic liquids
Ejigu, Andinet; Walsh, Darren A.
DARREN WALSH DARREN.WALSH@NOTTINGHAM.AC.UK
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|
|Publisher||American Chemical Society|
|Peer Reviewed||Peer Reviewed|
|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|
|Keywords||ionic liquid; CO displacement; electrocatalysis; potential of zero charge; ion adsorption|
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