Publication detail

Ion Distributions at ElectrifiedWater-Organic Interfaces: PB-PMF Calculations and Impedance Spectroscopy Measurements

HOU, B. BU, W. LUO, G. VANÝSEK, P. SCHLOSSMAN, M.

Original Title

Ion Distributions at ElectrifiedWater-Organic Interfaces: PB-PMF Calculations and Impedance Spectroscopy Measurements

Type

journal article in Scopus

Language

English

Original Abstract

The interface between two immiscible electrolyte solutions consisting of alkali chlorides in water and the organic electrolyte BTPPATPFB in 1,2-dichloroethane is characterized with X-ray reflectivity, interfacial tension and impedance spectroscopy measurements over a range of applied voltage between the bulk solutions. X-ray reflectivity probes the interfacial ion distribution on the sub-nanometer length scale, whereas interfacial tension and impedance spectroscopy characterize quantities such as interfacial excess charge and differential capacitance that represent integrations over the interfacial ion distribution. Predictions of interfacial ion distributions by the recently introduced PB-PMF method, which combines Poisson's equation with ion potentials of mean force, provide excellent agreement, within one to two experimental standard deviations, with both X-ray reflectivity and interfacial tension measurements. However, the agreement with the differential capacitance measured by impedance spectroscopy, and modeled by the Randles equivalent circuit, is not as good. Values of measured and calculated differential capacitance can deviate by as much as 20% for applied electric potential differences larger than approximately ±100 mV. These comparisons indicate that our understanding of the ion distributions that underlie these measurements is adequate, but that further understanding of the modeling of impedance spectroscopy data is required for quantitative agreement at larger applied electric potential differences.

Keywords

Impedance; modelling; ITIES; PB-PMF

Authors

HOU, B.; BU, W.; LUO, G.; VANÝSEK, P.; SCHLOSSMAN, M.

RIV year

2015

Released

7. 9. 2015

Publisher

The Electrochemical Society

Location

New Jersey

ISBN

0013-4651

Periodical

JOURNAL OF THE ELECTROCHEMICAL SOCIETY

Year of study

162

Number

12

State

United States of America

Pages from

H890

Pages to

H897

Pages count

8

URL

Full text in the Digital Library