INSULATOR-ELECTROLYTE INTERFACE

The mechanism of electrolytic rectification would depend on the properties of the insulator-electrolyte interface, if anodic oxide films were sufficiently perfect. These properties are reviewed and a quantitative theoretical interpretation given. Correlations between different experimental measurements and a predictable dependence of observables on controllable parameters should be achieved through use of the equations presented if the metal-insulator-electrolyte structure is responsible for a particular case of electrolytic rectification. Formulas derived after making the assumption that all of the equilibrium potential difference in the insulator-electrolyte interface is located within the solid, seem to be in agreement with experiment. Justification of this approximation is not found in the classical description of the interface, however, since point charged particles are able to approach the hypothetical “surface” without restriction. These formulas would suggest that the layer becomes unrealistically thin at high injection levels. It appears from the solution of a simplified quantum mechanical problem, that electrostatic compression of the real space charge layer might be avoided by “squeezing” of the particles out of the bottom of the potential well. © 1968, The Electrochemical Society, Inc. All rights reserved.