Modified titanium electrodes Application to Ti/TiO2/PbO2 dimensionally stable anodes

Titanium is a valve metal able to withstand corrosion due to the presence of a passivating layer of titanium oxide on its surface But due to that more or less insulating layer titanium cannot be used directly as an anodic material However modification of the surface of a Ti/TiO2 substrate may lead to the formation of new structures Ti/TiO2/M or Ti/TiO2/OX in which M is a metal such as platinum and OX a conducting oxide exhibiting electrocatalytic properties These structures have interesting electrochemical properties and may be used as efficient electrode materials In this paper after a review of the electrochemical behaviour of these structures we give new results concerning the selective electrodeposition of lead dioxide on Ti/TiO2 substrates and we propose an interpretation of the results taking into account the dielectric properties of the underlying TiO2 It is shown that there is a dramatic decrease of the resistance of the electrode when a PbO2 layer is electrodeposited onto a Ti/TiO2 structure That effect allows the preparation of electrodes (low-cost DSAs) that may be used as anodes in spite of the presence of the underlying TiO2 layer that layer being useful to avoid corrosion of the titanium substrate At last the effect of stabilization of the underlying TiO2 layer is discussed (C) 2010 Elsevier Ltd All rights reserved