Deoxidation of Titania Foams

Abstract

The electro-deoxidation of titanium dioxide foams in molten calcium chloride is presented. Studies performed with a three electrode cell, with cathodes of porous titania foams of different open porosity, a graphite anode and a wolframium pseudo-reference electrode. Experiments were carried out under cathodic potential control and at different applied potentials. By analyzing the compositions of samples prepared at different cathode potentials, and compared against the results from other studies it was revealed that within 16 h of the process oxygen contents may be lowered from 40 to 30wt.% in 1 mm thick surface layer of titania foam. It demonstrated that the current efficiency was low and that a barrier remains in the electroreduction of TiO2 to Ti. This communication identifies the anomalous electro-migration of oxygen vacancies in reduced TiO2 as an inherent feature and barrier to the solid-state reduction of TiO2 to Ti.