1992 Volume 1992 Issue 152 Pages 106-114
Two types of new carbon ultramicroelectrodes for the use of electrochemical detector were developed by using graphite/carbon composite PFC (Plastic Formed Carbon), and their electrochemical behaviors were evaluated by cyclic voltammetry. One of the carbon samples used had a fiber shape with 30μm in diameter. The other had a rod shape with 300μm in diameter, which was formed to be a conical shape at an end of the rod by electrochemical oxidizing in KOH solution as an anode. The diameter of the tip of the conical electrode was 10μm. These samples were made into electrodes by silicon oil impregnation and by insulating on the surface. Both microelectrodes were found to have excellent properties in electrochemical behavior, as compared with a Pt electrode of the same type. In electrochemical behavior, a relationship between the microstructure of carbon electrode and heterogeneous electron transfer activity was found. Crystal edge plane of graphite was necessary for fast electron transfer, and electrochemical activation correlated with crystal edge plane density. By silicon oil impregnation reduced the blank current and enhanced the S/N ratio. The peakpotentials of the C-V curves of Fe (CN) 64-/3-were in good agreement between both electrodes. Reproducibility of the electrode reactions of the redox ions were good. The blank current was proportional to the potential sweep rates, υ, in the range between 0.1 and 2.0V (vs SCE). Relation between υ1/2 and the peak current were linear.
