Electrochemical behavior of W⁶⁺ in NaCl-KCl-NaF-WO₃ molten salt system

The electrochemical reduction mechanism of W⁶⁺ on the tungsten electrode at 973 K was studied by the methods of cyclic voltammetry, chronopotentiometry, chronoamperometry and square wave voltammetry, and by using NaCl-KCl-NaF and WO₃ as molten salt and raw material respectively. The results show that the reduction process of W(Ⅵ) ion is carried out in two steps: the first one is a two-electron transfer process, and the electrode reaction equation is W⁶⁺ + 2e^-→W⁴⁺; the second one is a four-electron one, and the electrode reaction equation is W⁴⁺ + 4e^-→W. The two depositing processes of tungsten ion are both quasi-reversible reactions. The reduction process of W(Ⅵ) ion on the tungsten electrode is controlled by diffusion whose coefficient is 1.05×10^-9 cm² /s.