Kinetics and mechanism of anodic chlorine and oxygen evolution reactions on transition metal oxide electrodes

A short résumé of the data on kinetics of chlorine reaction at RuO2 and RuO2 —TTiO2 electrodes is given. The three step mechanism of the reaction with the rate determining transfer of the second electron and the formation of the nominally unipositive chlorine as an intermediate is substantiated. The applicability of an analogous mechanism to the oxygen evolution reaction is discussed as well as the possibility of participation in the process of higher oxidation states of ruthenium. Some analogies between anodic processes at RuO2 and other transition metal oxides (perovskites MNi(Co)O3, pyrochlores M2Re2O7, spinels MCo2O4, MCr2O4) were pointed out.