Electrochemical Behavior of ReO^-₄ in Perchloric Acid System

⁹⁹Tc, a long-lived(T_1/2=2.13×10⁵ a) nuclide, has a complex routing in PUREX process due to its various oxidation in the reprocessing of the spent nuclear fuel which gets special attention. Rhenium is usually used as a simulant to study the chemical behavior of technetium since they have similar chemical behaviors. The electrochemical behavior of ReO^-₄ in 0.5 mol/L HClO₄ solution was studied by cyclic voltammetry, differential pulse voltammetry and chronopotentiometry. The result shows that there is a multi-step electron transfer process in the electrochemical reaction of rhenium. Re(Ⅶ) is easily reduced to Re(Ⅳ) by three-electron transfer on platinum electrode, on which Re(Ⅶ) can also be gradually reduced to Re(Ⅵ) and Re(Ⅴ) through single electron transfer. When the reduction potential is lower than 0 V, Pt-Had is electrochemically formed on the platinum electrode surface and subsequently reduce Re(Ⅳ) to Re(Ⅲ). In addition, the electrochemical study of rhenium on gold electrode shows that Re(Ⅶ) is gradually reduced to Re(Ⅲ) by multi-step electron transfer and the Re(Ⅲ) can be further deposited as rhenium.