Characterization of an AgBr-Ag2S-As2S 3-HgI2 ion-selective electrode membrane: A X-ray photoelectron and impedance spectroscopy approach

B Pejcic; Roland De Marco

doi:10.1016/j.apsusc.2004.01.040

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Characterization of an AgBr-Ag2S-As2S 3-HgI2 ion-selective electrode membrane: A X-ray photoelectron and impedance spectroscopy approach

Journal article

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Characterization of an AgBr-Ag2S-As2S 3-HgI2 ion-selective electrode membrane: A X-ray photoelectron and impedance spectroscopy approach

B Pejcic and Roland De Marco

Applied Surface Science, Vol.228(1-4), pp.378-400

2004

DOI: https://doi.org/10.1016/j.apsusc.2004.01.040

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Abstract

chalcogenide

mercury ion-selective electrode

EIS

XPS

photo-oxidation

This paper presents the results of a detailed surface study of a chalcogenide (AgBr-Ag2S-As2S3-HgI2) mercury (Hg(II)) ion-selective electrode (ISE) using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). EIS has shown that the Hg(II) ISE undergoes a photo-oxidation reaction in the presence of light. By contrast, XPS revealed that the outer surface layer of AgBr-Ag2S-As2S 3-HgI2 becomes hydrated and depleted with respect to arsenic on exposure to air/water during membrane preparation/treatment. XPS failed to detect any arsenic compound which may be associated with oxygen, suggesting that the As-O species becomes removed from the surface. The adsorption of mercury (Hg2+) and various ions (i.e., OH-, NO3 - and Cl-) have been studied, and a mechanism for their action is proposed. SEM and XPS have revealed that chloride ions undergo specific adsorption onto AgBr sites and the reaction is dictated by kinetic factors, whereas nitrate preferentially reacts with the chalcogenide arsenic component most likely via a redox process. By contrast, EIS revealed a decrease in charge transfer resistance after extended exposure of the AgBr-Ag2S-As2S3-HgI2 membrane in Hg2+ electrolyte, and XPS identified various changes in the surface species. It is proposed that the response mechanism of the chalcogenide Hg(II) ISE membrane involves a combined charge transfer and ion exchange reaction in Hg2+ electrolyte. © 2004 Elsevier B.V. All rights reserved.

Details

Title: Characterization of an AgBr-Ag2S-As2S 3-HgI2 ion-selective electrode membrane: A X-ray photoelectron and impedance spectroscopy approach
Authors: B Pejcic (Author) - Curtin University of Technology
Roland De Marco (Author) - Curtin University of Technology
Publication details: Applied Surface Science, Vol.228(1-4), pp.378-400
Publisher: Elsevier BV, North-Holland
Date published: 2004
DOI: 10.1016/j.apsusc.2004.01.040
ISSN: 0169-4332
Organisation Unit: University of the Sunshine Coast, Queensland; Office of the Deputy Vice-Chancellor (Research and Innovation)
Language: English
Record Identifier: 99448742602621
Output Type: Journal article

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Web Of Science research areas: Chemistry, Physical; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter