Electrocatalytic properties of Ru+Ti+Ce mixed oxide electrodes for the Cl-2 evolution reaction

A series of ternary oxides of nominal composition Ru0.3Ti(0.7-x)CexO2 was prepared by thermal decomposition on Ti supports and used as electrodes to study the effect of substituting Ce for Ti on the kinetics and electrocatalysis of the Cl-2 evolution reaction. The surface properties were evaluated by cyclic voltammetry. Integration of the voltammetric curves provided the voltammetric charge, q*, which is proportional to the active surface area. Kinetic data showed that Cl-2 evolution occurs with a single mechanism over the whole explored potential range and at all electrode compositions. Fractional reaction orders with respect to both Cl- and H+ revealed double-layer effects attributed to the occurrence of Cl- specific adsorption. The apparent activity increased with CeO2 content, whereas the true electrocatalytic properties, estimated by normalizing the current to unit surface charge, decreased in the presence of CeO2 with a minimum of 10% CeO2. The presence of CeO2 also makes the oxide layers more prone to mechanical erosion by the evolving gas bubbles. (C) 1997 Elsevier Science Ltd.