Progress in the understanding of the mechanism of chlorine evolution at oxide electrodes

After introductory general thermodynamic and kinetic considerations, the possible factors which can distort the kinetic measurements of Cl2 evolution at oxide electrodes giving rise to mistaken mechanisms are analyzed as resulting from a retrospective analysis of the literature. Such factors include: mixed potentials, porosity, removal of produced Cl2, bubble formation, support passivation, morphology and composition of the active layer, ion specific adsorption, pH effects. In the light of the insight step-by-step gained on the possible interference by the above experimental factors, the various proposals of mechanism are reviewed, mainly chronologically, to highlight the conceptual and experimental progress made in this field in the past 15 years. Conclusions are finally drawn which enable some possible topics for further research in this area to be discussed.