The Structure of the Electrochemical Interface of a Mechanically Renewable Graphite Electrode with Aqueous Solutions of Surface Inactive Electrolytes

Abstract

Using electrochemical measurements on electrodes with the mechanically renewable surface, the behavior of graphite electrodes is studied in aqueous solutions of surface inactive electrolytes. The potential region is found in which this electrode behaves as the ideally polarizable electrode. The capacitance curves measured in this potential region demonstrate certain peculiarities. Thus, at potentials corresponding to the positive surface charge (σ > 0), the capacitance of the electric double layer (EDL) on the graphite electrode is approximately 1.5–2 times lower as compared with mercury-like metals. At the same time, these values come closer to one another and practically coincide as the potential shifts in the region of negative surface charges (σ < 0). The analysis of experimental data shows that these peculiarities of capacitance curves on the graphite electrode are associated with the semiconductor properties of this material. A new approach to the model description of experimental data is proposed and substantiated. This allows the important semiconductor parameters such as the flat-band potential and the concentration of charge carriers in the conduction zone of the graphite material to be assessed.