Evaluation of iridium oxide electrodes formed by potential cycling as pH probes

Hitchman, Michael L.; Ramanathan, Subramaniam

doi:10.1039/an9881300035

Cited by 96 publications

(90 citation statements)

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“…A hydrous IrOx layer is then produced by cycling the Ir electrode potential between À0.25 and 1.25 V (vs. SCE) [44]. Various numbers of cycles and scan rates have been suggested for optimal film growth [3,9,23,[45][46][47]. We find that good results are obtained by continuous potential cycling in unstirred, aerated 0.5 M H 2 SO 4 solution between À0.25 and 1.25 V (vs. SCE) at a scan rate of 3 V/s for 1-6 h at room temperature.…”

Section: Iridium Oxide Film Growth and Voltammetric Behaviormentioning

confidence: 99%

Microparticle-based iridium oxide ultramicroelectrodes for pH sensing and imaging

El-Giar

Wipf

2007

Journal of Electroanalytical Chemistry

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Section: Iridium Oxide Film Growth and Voltammetric Behaviormentioning

confidence: 99%

Microparticle-based iridium oxide ultramicroelectrodes for pH sensing and imaging

El-Giar

Wipf

2007

Journal of Electroanalytical Chemistry

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“…17,18 SECM pH probes employing a variety of metal/metal oxides have been reported previously. 15,[19][20][21] Iridium oxide-based pH ultramicroelectrodes have proven particularly popular for spatially resolved pH measurements in SECM, owing to their fast response time, long termstability over a wide range of pHs, temperatures and pressures, all-solid format and capability for miniaturization. 15,22,23 Iridium oxide pH electrodes have been prepared by either electrochemical oxidation, 22 thermal decomposition 24 and sputter deposition 25 of iridium metal, or by the electrodeposition of iridium oxide from alkaline solutions of iridium salts.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of Dual Function Nanoscale pH-Scanning Ion Conductance Microscopy (SICM) Probes for High Resolution pH Mapping

et al. 2013

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(2013) Fabrication and characterization of dual function nanoscale pH-scanning ion conductance microscopy (SICM) probes for high resolution pH mapping. Analytical Chemistry, Volume 85 (Number 17). pp. 8070-8074 Permanent WRAP url: http://wrap.warwick.ac.uk/57249 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work of researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-forprofit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work http://dx.doi.org/10.1021/ac401883n The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. AbstractThe easy fabrication and use of nanoscale dual function pH-scanning ion conductance microscopy (SICM) probes is reported. These probes incorporate an iridium oxide coated carbon electrode for pH measurement and an SICM barrel for distance control, enabling simultaneous pH and topography mapping. These pH-SICM probes were fabricated rapidly from laser pulled theta quartz pipets, with the pH electrode prepared by in-situ carbon filling of one of the barrels by the pyrolytic decomposition of butane, followed by electrodeposition of a thin layer of hydrous iridium oxide. The other barrel was filled with an electrolyte solution and Ag/AgCl electrode as part of a conductance cell for SICM. The fabricated probes, with pH and SICM sensing elements typically on the 100 nm scale, were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy and various electrochemical measurements. They showed a linear super-Nernstian pH response over a range of pH (pH 2-10). The capability of the pH-SICM probe was demonstrated by detecting both pH and topographical changes during the dissolution of a calcite microcrystal in aqueous solution. This system illustrates the quantitative nature of pH-SICM imaging, because the dissolution process changes the crystal height and interfacial pH (compared to bulk) and each is sensitive to the rate. Both measurements reve...

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“…2). The potential of the iridium oxide pH-sensitive reference electrode changes toward the negative direction with an increase in the pH with a sensitivity of −68 mV/pH (Hitchman and Ramanathan, 1988). However, it is difficult to cause a significant change in the wettability of the valve electrode only by the change in the potential of the reference electrode.…”

Section: Principle Of Operationmentioning

confidence: 98%