Electrodes based on Magnéli phase titanium oxides: The properties and applications of Ebonex® materials

Abstract

Magnéli phases are a range of substoichiometric oxides of titanium of the general formula TinO2n-1, (where n is between 4 and 10) produced from high temperature reduction of titania in a hydrogen atmosphere. These blue/black ceramic materials exhibit a conductivity comparable to that of graphite and can be produced in a number of forms, such as tiles, rods, fibres, foams and powders. While these materials have been studied for many years, they have only recently received interest for use as ceramic electrode materials, commercially termed 'Ebonex®', and are beginning to challenge precious metal coated anodes for some applications in aggressive electrolytes. Other uses for these materials include electrowinning, electroplating, battery materials, impressed current cathodic protection anodes, electrochemical soil remediation, oxidation of organic wastes, flexible cable materials and electrophoresis. The scope of this review considers the structure and properties of Magnéli phase titanium oxide materials, together with their electrochemical behaviour and applications.