ELECTROCHEMICAL-BEHAVIOR OF VANADIUM(V) VANADIUM(IV) REDOX COUPLE AT GRAPHITE-ELECTRODES

The electrochemical behaviour of the V(V)/V(IV) couple has been studied at a graphite disc electrode in sulfuric acid using both cyclic and rotating-disc voltammetry. The results from the latter technique have revealed that the cathodic and anodic characteristics of this redox couple are quite different. The diffusion coefficient for V(IV), 2.14 x 10(-6) cm2 s-1, is independent of the vanadium concentration. For V(IV) oxidation, the electrode kinetic parameters i0 and alpha have values of 2.47 X 10(-4) A cm-2 and 0.71, respectively. The exchange current density, i0, for the V(V)/V(IV) reaction has been obtained at both graphite felt and reticulated vitreous carbon electrodes.