The Electrochemical Behavior of Graphite Fiber‐Epoxy Composite Electrodes Containing Varying Fiber Orientations

Abstract

The electrochemical behavior of carbon fiber epoxy matrix electrodes has been tested. A simple outer‐sphere redox couple was used as the test reaction. The results indicate no dependence on fiber orientation (random, parallel, or perpendicular). Rate constants are not significantly different from those observed for the same reaction on Pt electrodes, indicating that the catalytic activity plays little or no role in determining the kinetics of this reaction. Chronoamperometric measurements at short times, in the millisecond range, reveal the unique features of composite electrodes as ensembles of microelectrodes.

Electrochemical Characterization of Binderless, Recompressed Exfoliated Graphite Electrodes: Electron-Transfer Kinetics and Diffusion Characteristics

“…If the surface pretreatment results in heterogeneity, then it may also affect the diffusion of electroactive species toward the electrode surface. It is already reported that the diffusion of electroactive species is affected by surface preparation when surface heterogeneity, in the form of roughness, is of the order of few micrometers. , SEM studies on the EG electrode surface show that the polished electrode has defect sites distributed on the predominantly basal plane oriented surface. Roughening the surface leads to the exposure of a high fraction of edge planes.…”

“…In the case of EG, the edge planes act as active sites and the basal plane region acts as a low-active or inactive region. Nonlinear diffusion is also reported to occur on polymer-carbon composite electrodes. − The polymer acts as the blocking surface and the carbon particles act as the active sites. The time scale at which the linear diffusion starts to be predominant changes with the roughness associated with the surface.…”

“…This depends on the particle size and the loading of carbon particles in the inert matrix. Deviation of the current versus (time) -1/2 plots from Cottrell behavior is an indication of a nonlinear type of diffusion behavior. − …”

Carbon Composite Microelectrodes: Charge Percolation and Electroanalytical Performance

“…[11][12][13][14] Moreover, the smallest composite "microelectrode" reported thus far has a diameter on the order of 200 µm. 12 In addition, despite the great variety of available materials for the preparation of rigid conducting composites, only epoxy-graphite [11][12][13] and silicagraphite 14 composites have been used for electrode construction.…”

“…Beyond traditional forms, such as pyrolized carbon and carbon fibers, conducting composite materials have been applied in the construction of electroanalytical devices since Adams' seminal work . However, despite the great variety of electrode shapes and sizes that can be created using disperse rigid conducting composites, only a few examples of microelectrodes based on these materials can be found in the literature. − Moreover, the smallest composite “microelectrode” reported thus far has a diameter on the order of 200 μm . In addition, despite the great variety of available materials for the preparation of rigid conducting composites, only epoxy−graphite − and silica−graphite composites have been used for electrode construction.…”