Voltammetric pH sensing using carbon electrodes: glassy carbon behaves similarly to EPPG

Lu, Minghui; Compton, Richard G.

doi:10.1039/c4an00866a

Cited by 48 publications

(66 citation statements)

References 37 publications

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“…It is apparent that the larger window produced the most resolved peaks. The mechanism for the oxidation/reduction reaction of quinones, in buffered solutions, involves a 2e − oxidation that converts the methoxy to the equivalent quinone, followed by a 2e − /2H + exchange to form the hydroxy-quinone [17,18,40]. The potentials at which the redox reactions take place are pH dependent, as the oxidation induces a loss of protons.…”

Section: Optimisation Of the Fbrr-modified Voltammogrammentioning

confidence: 99%

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The aqueous deposition of a pH sensitive quinone on carbon paste electrodes using linear sweep voltammetry

Herdman

Breslin

Finnerty

2018

Journal of Electroanalytical Chemistry

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Herein, we report the electrodeposition of a quinone containing diazonium salt onto the surface of carbon paste electrodes (CPE). An extensive characterisation revealed the optimum deposition characteristics to be obtained using Linear Sweep Voltammetry (LSV) over the potential range +400 mV to −800 mV vs. SCE at 100 mV/s, for five sweeps in 0.1 M H 2 SO 4. The corresponding FBRR-modified CPE was cycled in phosphate buffered saline over the potential range +800 mV to −700 mV vs. SCE at 100 mV/s. The anodic peak potential demonstrated excellent stability over 400 cycles and a Nernstian response was recorded (−59 ± 3 mV/pH, n = 39, r 2 = 0.99). The continuous monitoring of pH changes within the same solution exhibited Nernstian behaviour also, confirming the efficacy of the FBRR-modified CPEs for in situ pH monitoring. An extensive shelf-life investigation identified retention of FBRR-modified CPEs sensitivity over 28 days when stored under air conditions at 4°C. The work described within confirms the effectiveness of FBRR-modified CPEs to perform continuous pH monitoring over a small pH range of physiological relevance. (59 mV) per pH unit. Carbon based materials and sensors have been widely used in the field of electrochemistry, because of their good electrical conductivity, ease of modification, low expense [4] and relatively wide operating

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Section: Optimisation Of the Fbrr-modified Voltammogrammentioning

confidence: 99%

“…Voltammetric pH sensors, which measure the redox potential of a pH dependent moiety, have demonstrated excellent performance in the past [17][18][19], are cost effective and easily miniaturised. The respective redox processes can be quantified using the Nernst equation, yielding the following response at 25°C:…”

Section: Introductionmentioning

confidence: 99%

The aqueous deposition of a pH sensitive quinone on carbon paste electrodes using linear sweep voltammetry

Herdman

Breslin

Finnerty

2018

Journal of Electroanalytical Chemistry

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“…based on the limiting current response of a microelectrode [14] or on dual-plate microtrench electrodes [15]) offer advantages for proton concentration deter-mination at least over limited proton concentration ranges. A new class of "reference-less" pH sensors based on the voltammetric response of pH-dependent surface redox systems has been devel-oped by Compton and coworkers based for example on quinone functionalities grafted onto glassy carbon or graphite surfaces [16][17][18][19][20]. Other types of pH sensor concepts have been proposed, for example a pH-dependent impedance response was reported for aligned single walled carbon nanotubes [21].…”

Section: Introductionmentioning

confidence: 99%

Carbonization of polymers of intrinsic microporosity to microporous heterocarbon: Capacitive pH measurements

Hernandez

Iniesta

Montiel

et al. 2017

Applied Materials Today

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A nitrogen-containing polymer of intrinsic microporosity (PIM-EA-TB-H2 ; nitrogen adsorption surface area 846 m 2 g −1) is vacuum carbonized at 700 • C and thereby directly without post-treatment converted into a microporous heterocarbon (cPIM; N2 adsorption surface area 425 m 2 g −1). Nitrogen functional-ities in the polymer backbone are retained in the heterocarbon and appear responsible for unusual time-, electrolyte-, and pH-dependent properties. Electrochemical characterization suggests a high specific capacitance (typically 50 F g −1) but only after prolonged immersion in aqueous HClO4. The timedependent increase in capacitance during immersion is assigned to slow hydration and ingress of HClO4 into hydrophobic micropores (H2 SO4 or H3 PO4 are more hydrophilic and much less effective). Once hydrated, the microporous heterocarbon exhibits pH-dependent capacitance "switching" over a wide pH range and analytical applications as "capacitive" pH sensor are proposed. .

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“…For example, studies of Fe(CN) 6 3-/4-found standard rate constant, k 0 , values at the basal plane ranging from nearly zero (k 0 < 10 -9 cm s -1 ) 31 to little activity (k 0 < 10 -6 cm s -1 ) 22,24 . The hugely enhanced activity at step edges, considered to have a standard rate constant up to 10 7 times higher than the basal surface, was ascribed to the higher local density of electronic states (LDOS) at step edges 24,32 or to catalysis by specific functional groups 33,34 (even for outer-sphere redox couples). These ideas entered textbooks 35,36 and were extrapolated to explain the electrochemical activity of CNTs and graphene.…”

Section: Introductionmentioning

confidence: 99%

Electrochemistry at highly oriented pyrolytic graphite (HOPG): lower limit for the kinetics of outer-sphere redox processes and general implications for electron transfer models

Zhang

Cuharuc

Güell

et al. 2015

Phys. Chem. Chem. Phys.

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Original citation:Zhang, Guohui, Cuharuc, Anatolii S., Güell, Aleix G. and Unwin, Patrick R.. (2015) Electrochemistry at highly oriented pyrolytic graphite (HOPG) : lower limit for the kinetics of outer-sphere redox processes and general implications for electron transfer models. Physical Chemistry Chemical Physics (Number 17). pp. 11827-11838. Permanent WRAP url: http://wrap.warwick.ac.uk/67805 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 statement:First published by Royal Society of Chemistry 2015 http://dx.doi.org/10.1039/C5CP00383K A note on versions: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. This simple configuration allows measurements to be made on a very short time scale after cleavage of HOPG, so as to minimise possible effects from (atmospheric) contamination, and with minimal, if any, change to the HOPG surface. However, the droplet-cell geometry differs from more conventional electrochemical setups and is more prone to ohmic drop effects. The magnitude of ohmic drop is elucidated by modelling the electric field in a typical droplet configuration. These simulations enable ohmic effects to be minimised practically by optimising the positions of the counter and reference electrodes in the droplet, and by using a concentration ratio of electrolyte to redox species that is higher than used conventionally . It is shown that the ET kinetics for all of the redox species studied herein is fast on all grades of HOPG and lower limits for ET rate constants are deduced. For IrCl 6 2-/3-and Fe(CN) 6 3-/4-, ET on HOPG is at least as fast as on Pt electrodes, and for Ru(NH 3 ) 6 3+/2+ ET kinetics on HOPG is comparable to Pt electrodes. Given the considerable difference in the density of electronic states (DOS) between graphite and metal electrodes, the results tend to suggest that the DOS of the electrode does not play an important role in the ET kinetics of these outer-sphere redox couples over the range of values encompassing HOPG and metals. This can be rationalised because the DOS of all of these different electrode ma...

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Voltammetric pH sensing using carbon electrodes: glassy carbon behaves similarly to EPPG

Cited by 48 publications

References 37 publications

The aqueous deposition of a pH sensitive quinone on carbon paste electrodes using linear sweep voltammetry

The aqueous deposition of a pH sensitive quinone on carbon paste electrodes using linear sweep voltammetry

Carbonization of polymers of intrinsic microporosity to microporous heterocarbon: Capacitive pH measurements

Electrochemistry at highly oriented pyrolytic graphite (HOPG): lower limit for the kinetics of outer-sphere redox processes and general implications for electron transfer models

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