Electrochemical properties of graphite fibre/epoxy composite electrodes
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The electrochemical behaviour of two types of carbon fibre/epoxy composite electrodes was studied and compared to that of glassy carbon. Background currents are low over a range of about 2.1 V, allowing the study of electrochemical reactions from about −0.6 V to +1.50 V versus the in aqueous solutions.
Oxygen evolution studies over a wide pH range in buffered solutions yield exchange urrent densities in the range of 2–70 μA cm−2, with a minimum in neutral solutions. The Tafel slopes are high, in the range of 0.3–0.4 V in acid and neutral solutions, rising further in alkaline solutions.
The limiting current density for the oxidation of I− ions was equal, within experimental error, to that found for glassy carbon, although about half the surface consists of inactive epoxy matrix material. Such behaviour is consistent with recent theoretical calculations for a partially inactive electrode surface, as long as the Nernst diffusion layer is comparable with or larger than the gaps between electroactive areas on the surface.
KeywordsEpoxy Glassy Carbon Electrochemical Property Electrochemical Behaviour Diffusion Layer
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