Electrochemical behavior of the Ⅴ(Ⅳ)/Ⅴ(Ⅴ) couple in sulfuric acid medium

The electrochemical behavior of the Ⅴ(Ⅳ)/Ⅴ(Ⅴ) redox couple at a glassy carbon electrode was investigated. Cyclic voltammetry(CV) results indicated that electrode process of the Ⅴ(Ⅳ)/Ⅴ(Ⅴ) couple was electrochemically quasi-reversible with a rate constant of 8×10 -4 cm/S . Increasing concentration of sulfuric acid was electrochemically favourable for the Ⅴ(Ⅳ)/Ⅴ(Ⅴ)couple while elevated temperature was unfavourable for this system. Constant-current electrolysis results showed that current efficiency of more than 95 % could be achieved, which indicated that the Ⅴ(Ⅳ)/Ⅴ(Ⅴ) couple had excellent electrolytic performance and was suitable for the application as the anolyte of redox flow batteries.