Quantitative Relationship between Electron Transfer Rate and Surface Microstructure of Laser-Modified Graphite Electrodes. (Reannouncement with New Availability Information).

摘要

Previous Investigations demonstrate that increases in electron transfer rate constant, k deg, 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 deg obs) and k deg obs for Fe(CN)6(3-/4) on HOPG were measured as functions of power density of the activating laser. Over a power density range from 0 to 130 MW CM-2, k deg, obs Increased by more than 5 orders of magnitude while C deg obs. Increased by a factor of 8. Both k deg obs and C deg obs may be expressed as linear combinations of the basal and edge plane k deg and C deg values, weighted by the fractional coverage of edge plane on the electrode surface (fe). Determinations of fe from both k deg obs and C deg 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 actively of laser-modified HOPG iIs predominantly dependent on edge plane density.