The electrical double layer at the [BMIM][PF6] ionic liquid/electrode interface - Effect of temperature on the differential capacitance

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Fernando Silva (Author) FCUP; Cristiana Gornes (Author) Other; Marta Figueiredo (Author) Other; Renata Costa (Author) Other; Ana Martins (Author) Other; Carlos M Pereira (Author) FCUP

Journal

Title: Journal Of Electroanalytical Chemistry

Vol. 622 No. 2

Pages: 153-160

ISSN: 1572-6657

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 143 Citations

Scopus - 144 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-VH4

DOI: 10.1016/j.jelechem.2008.05.014

Abstract (EN): Impedance spectra (50 kHz-1 Hz) were acquired and used to obtain the differential capacitance at the interfaces between 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6] ionic liquid and three different electrode materials (Hg, Pt, and glassy carbon (GC)) as a function of the applied potential. The electrocapillary curve for the Hg/[BMIM][PF6] interface was obtained from drop time measurements, from which the potential of zero charge was calculated to be -0.39 V (Ag wire). The potential of zero charge is 0.30 V less negative than the potential of differential capacitance minimum. This disagreement suggests that the differential capacitance minimum is not related to a classical diffuse layer minimum. Additional support to this conclusion was obtained from positive temperature coefficient for the differential capacitance in contrast to the negative temperature predicted by the classic Gouy-Chapman model. The results do not support the recent model predictions of bell shaped capacitance curves for room temperature ionic liquids, RTILs.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8