Process of direct electrochemical reduction of TiO_2

The products of electrochemical reduction of TiO_2 were examined by SEM, EDS and XRD. The results show that TiO_2 is reduced step by step from outside to inside and from high valence oxide to low valence oxide until to metal. The analysis of current and anode gases during electrolysis indicates that the average current efficiency is low and decreases with electrolysis time. The secondary reactions between CO, CO_2 and Ca evolved at cathode and short circuit caused by the produced black carbon are the main reasons resulting in low current efficiency. There are two ways to improve the current efficiency. First, the distance between the anode and cathode should be increased (enough) in order to limit the secondary reaction. Second, the molten salt at the surface should be drained continuously or the anode and cathode should be separated to prevent short circuit caused by black carbon.