alexa Quantitative Relationship between Electron Transfer Rate and Surface Microstructure of Laser-Modified Graphite Electrodes AnalChem 61: 1637-1641.


Toxicology: Open Access

Author(s): Ronald J Rice, Richard L McCreery

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Previous investigations demonstrate that increases in electron transfer rate constant, k°,on highly ordered pyrolytic graphite (HOPG) basal plane correlate with the appearance of edge plane defects and that such defects may be created with laser or electrochemical pretreatment. In the current work both capacitance (C°obs) and k°obs for Fe(CN)63-/4- on HOPG were measured as functions of power density of the activating laser. Over a power density range from O to 130 MW cm-2, k°obs increased by more than 5 orders of magnitude while C°obs increased by a factor of 8. Both k°obs and C°obs may be expressed as linear combinations of the basal and edge plane k° and C° values, weighted by the fractional coverage of edge plane on the electrode surface (fe.). Determinations of fe from both k°obs and C°obs are quantitatively consistent and in both cases increase with power density above a threshold of 45 MW cm-2. Although effects of surface roughness may also be involved, the results indicate that the electron transfer activity of laser-modified HOPG is predominantly dependent on edge plane density.

This article was published in  Analytical Chemistry and referenced in Toxicology: Open Access

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