The electrical doublelayer of carbon and graphite electrodes. Part I. Dependence on electrolyte type and concentration

The electrical double layer capacity per unit of the true surface area of graphitized carbon cloth and carbon black was investigated at various conditions. It was found independent of the type and valency of cations and anions as long as these are not specifically adsorbed. It was also independent of concentration and did not show the typical deep minimum at low concentrations. The only feature observed in the capacity-potential curve is a flat minimum. In order to interpret the results, surface heterogeneity and the existence of localized π-electron states at the outer graphitic layer of the electrode had to be assumed.