Abstract: The cathodic reduction of SbO~+ ions in sodium sulphate solution at pH 4.0 has been investigated using potentiodynamic polarization at rotating disc electrode (RDE), rotating ring disc electrode(RRDE) and AC impedance techniques. Results show that SbO~+ ions can be eventually reduced to stibine SbH_3 through a 6-electron process, whose formation is confirmed by RRDE experiments. The reduction is diffusioncontrolled at potentials negative to -1.28 V. The values of the diffusion coefficient of SbO~+ ions calculated on the basis of the experimental results for 3-electron and 6-electron reduction are very consistent; they are (1.45±0.15)×10~(-6) cm~2·s~(-1) and (1.47±0.15)×10~(-6) cm~2·s~(-1), respectively.

Key words: Antimonyl ion, Stibine, Cathodic reduction, Diffusion coefficient, Activator