Historical development of theories of the electrochemical double layer

This review describes the evolution of important concepts related to potential drops at interfaces in electrochemical systems. The role of the thermodynamic theory of electrocapillarity of perfectly polarizable electrodes in the development of interfacial electrochemistry is emphasized. A critical analysis of the phenomenological models of the electrical double layer on ideally polarizable electrodes is given. Certain trends in studying solid electrodes with well-defined surfaces brought into contact with electrolyte solutions are summarized. Attention is drawn to several unsolved problems crucial for the future development of electrochemical surface science. Finally, some recent experimental data are analyzed for selected models.