Semiconductor electrochemistry approach to passivity and passivity breakdown of metals and metallic alloys

A critical appraisal of the use of the theory of semiconductors in characterising passive films on metals and alloys is provided, with special emphasis on the use of Mott – Schottky theory for the location of characteristic energy levels of the passive film – electrolyte junction. Some inconsistencies between theory and experimental results in the case of thin passive films are discussed together with possible alternative ways for overcoming such problems. The role of semiconducting properties in determining the pitting behaviour of passive films on W in solutions containing halide is presented and discussed. The validity of a recently proposed correlation between the solid state properties of passive films and the pitting potential is critically reviewed.