Voltammetric probing of pH at carbon nanofiber-Nafion-carbon nanofiber membrane electrode assemblies

Richard A Webster, Fengjie Xia, M Pan, Shichun Mu, Sara E C Dale, Shik Chi Tsang, Frank W Hammett, Christopher R Bowen, Frank Marken

Research output: Contribution to journalArticle

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Abstract

Methods are developed for using a carbon nanofiber membrane electrode assembly (cnMEA) for three-electrode electrochemical measurements in unsupported liquid or gaseous media. The carbon nanofiber membrane (ca. 20 m thickness) is hot-pressed from both sides onto a Nafion ion conductor film (ca. 50 m thickness). The resulting cnMEA is employed as both a counter electrode and working electrode (with an external SCE reference electrode) for the liquid phase oxidation of hydroquinone in (i) 0.5 M, (ii) 0.05 M, and (iii) 0.005 M aqueous NaHCO3, and (iv) in pure demineralised water. Well-defined voltammetric responses are obtained and pH effects are investigated. A gas-salt (di-ammonium sulphate) contact between the cnMEA working electrode and SCE reference electrode is then employed in a gas flow system to obtain voltammetric responses in contact with a humidified gas (N2, 80% relative humidity). Reversible redox cycling of entrapped hydroquinone is demonstrated and humidity and pH effects are observed. Ammonia gas effects on Faradaic currents are explored. Voltammetric measurements provide direct insight into the MEA processes and conditions.
Original languageEnglish
Pages (from-to)97-102
Number of pages6
JournalElectrochimica Acta
Volume62
DOIs
Publication statusPublished - 15 Feb 2012

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Carbon nanofibers
Membranes
Electrodes
pH effects
Gases
Contacts (fluid mechanics)
Atmospheric humidity
Electrochemical electrodes
perfluorosulfonic acid
Ammonium Sulfate
Liquids
Ammonia
Flow of gases
Salts
Ions
Oxidation
Water

Cite this

Voltammetric probing of pH at carbon nanofiber-Nafion-carbon nanofiber membrane electrode assemblies. / Webster, Richard A; Xia, Fengjie; Pan, M; Mu, Shichun; Dale, Sara E C; Tsang, Shik Chi; Hammett, Frank W; Bowen, Christopher R; Marken, Frank.

In: Electrochimica Acta, Vol. 62, 15.02.2012, p. 97-102.

Research output: Contribution to journalArticle

Webster, Richard A ; Xia, Fengjie ; Pan, M ; Mu, Shichun ; Dale, Sara E C ; Tsang, Shik Chi ; Hammett, Frank W ; Bowen, Christopher R ; Marken, Frank. / Voltammetric probing of pH at carbon nanofiber-Nafion-carbon nanofiber membrane electrode assemblies. In: Electrochimica Acta. 2012 ; Vol. 62. pp. 97-102.
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