Journal of the Brazilian Chemical Society
On-line version ISSN 1678-4790
SABZI, Reza E.. Electrocatalytic oxidation of thiosulfate at glassy carbon electrode chemically modified with cobalt pentacyanonitrosylferrate. J. Braz. Chem. Soc. [online]. 2005, vol.16, n.6a, pp. 1262-1268. ISSN 1678-4790. http://dx.doi.org/10.1590/S0103-50532005000700026.
An electroactive thin film of Cobalt pentacyanonitrosylferrate (CoPCNF) was electrodeposited on a glassy carbon electrode by cyclic voltammetry. The modified electrode exhibits good electrocatalytic activity toward oxidation of thiosulfate. The electrocatalytic oxidation of thiosulfate at glassy carbon electrode modified with CoPCNF as a working electrode has been studied by using cyclic voltammetry, rotating disk electrode (RDE) voltammetry and chronoamperometry in a solution of 0.25 mol L-1 KNO3 as a supporting electrolyte. A Tafel plot, derived from voltammograms indicated a one-electron charge transfer process, at rate determining step in the catalytic oxidation of thiosulfate. The kinetics of catalytic reaction was investigated and the average value of the rate constant (k), for the catalytic reaction and the diffusion coefficient (D) were evaluated by different approaches for thiosulfate and found to be (5.61 ± 0.14) ´102 (mol L-1)-1s-1 and (6.59 ± 0.70) ´10-6 cm2s-1 respectively.
Keywords : modified-electrode; glassy carbon electrode; cobalt pentacyanonitrosylferrate; electrocatalytic oxidation of thiosulfate.