Electrocatalytic characteristics of thiosulfate oxidation at nickel platedaluminum electrode modified with nickel pentacyanonitrosylferrate films

Nickel pentacyanonitrosylferrate (NiPCNF) films have been deposited on the surface of aluminum substrate by a simple electroless dipping method. The c yclic voltammogram of the resulting surface modified Al electrode prepared under optimum conditions, shows a well-behaved redox couple due to the [(Ni FeIII/II)-Fe-II(CN)(5)NO](0/-1) system. The NiPCNF films formed on the Al e lectrode show electrocatalytic activity towards the oxidation of thiosulfat e in sodium nitrate solution. a linear calibration plot is obtained over th e thiosulfate concentration range 5-110 mM and 0.001-100 mM, using linear s weep voltammetry and hydrodynamic voltammetry (at a fixed potential and sti rred solutions), respectively. The kinetics of the catalytic reaction were investigated using cyclic voltammetry, rotating disk electrode (RDE) voltam metry and chronoamperometry. The results were explained using the theory of electrocatalytic reactions at chemically modified electrodes. The average value of the rate constant for the catalytic reaction evaluated by the thre e different approaches, is 9 x 10(-1) cm s(-1). Further examinations of the modified electrodes show that the modifying layers (TiPCNF) on the aluminu m substrate show reproducible behavior and a high level of stability.