Book-keeping of Ion and Electron Currents in the Point Defect Model and Role of an Electron Channel at the metal/film Interface in Determining the Forms of the metal-film potential and the film-solution potential drops

Abstract: In any consistent electrochemical systems model that addresses more than one interface, the total current at the interfaces should be equal to one another and to the current in the external circuit. The point defect model of Macdonald and co-workers fails to recognize this basic requirement. Hence there is no assurance that currents predicted by the PDM will be the same at the metal/film and the film/solution interfaces. This deficiency is corrected in the present work. Besides, The point defect model lacks a proper book-keeping of ion and electron currents and in particular missed the role of a purely electron channel (e-channel) at the metal/film interface [1]. In this work we describe this book-keeping, include the e-channel and show how this affects the forms of the metal-film and film-solution potential drops.