Electrosynthesis of Ti2COn from TiO2/C Composite in Molten CaCl2: Effect of Electrolysis Voltage and Duration

Ti2COn powders with controllable oxygen contents have been successfully synthesized by electro-reduction of solid TiO2-graphite composite precursors in molten CaCl2. The effect of electrolysis time and applied cell voltage on the carbon and oxygen content of the product was systematically investigated. The reduction pathway of the composite electrode was studied based on the analysis of intermediate products using X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is suggested that the reduction starts with converting TiO2 and graphite to CaTiO3 and Ti2COn. The resulting CaTiO3 is then reduced to CaTi2O4 which is subsequently reduced to Ti2COn. The present graphite significantly accelerates the electro-reduction of TiO2. The oxygen content decreases with increasing the electrolysis cell voltage and prolonging the electrolysis time. It is found that the cell voltage and electrolysis duration should be strictly controlled to avoid oxygen-depletion in the final product. The obtained product shows good electronic conductivity at room temperature. This process exhibits a relatively high current efficiency for production of Ti2COn from TiO2-graphite composite. (C) 2013 The Electrochemical Society. All rights reserved.