Electrochemical Behaviors of Impermeable Carbon Electrodes Using Graphite/Carbon Composite

Abstract

An impermeable carbon electrode was developed as a new electrochemical detector. The electrode made of graphite/glassy carbon composite (30/70 weight ratio) was prepared by the Plastic Formed Carbon (PFC) method. The microstructure of the surface of the PFC electrode was observed by scanning electron microscopy. The impermeability and the electrochemical behavior of the electrode, in comparison with HOPG, were evaluated by cyclic voltammetry in solution of 18 M sulfuric acid. The SEM observation and the cyclic voltammetry suggest that the disk plane and the cylindrical plane of PFC electrode have similar microstructure and similar pattern of cyclic voltammograms of ferro-/ferri-cyanide ions in solution of potassium chloride to those of the edge plane and the basal plane of the HOPG, respectively. The potential window on the PFC electrode was + 1.6V to -1.3V in 1 M sulfuric acid solution (vs. SCE), and this potential range corresponds to that on a glassy carbon electrode. A peak current in a redox reaction of ferrocyanide and ferricyanide was proportional to the concentration of ferrocyanide and ferricyanide ions. No change was observed in the pattern of the cyclic voltammogram of ferro-/ferri-cyanide ion response in potassium chloride solution on the PFC electrode after 100 -day immersion of the electrode. The PFC electrode showed a stable response of the surface reaction, and the reproducibility was good. Although the anode peak, which corresponds to the formation of the first-stage graphite intercalation compound, was found in the CV curves, repeated-cycle experiment indicated that the surface of the PFC electrode was almost as impermeable as glassy carbon.