Electrocatalytic oxidation of nitrite at an aluminum electrode modified by a chemically deposited palladium pentacyanonitrosylferrate film

A simple electroless dipping method has been used for the deposition of the palladium pentacyanonitrosylferrate (PdPCNF) film on the aluminum electrode surface. This aluminum-based modified electrode (PdPCNF/Al) exhibits one pair of well-defined voltammetric peaks, which is ascribed to the redox process of the Fe center in the PdPCNF complex structure. The PdPCNF/Al modified electrode shows electrocatalytic activity for the oxidation of nitrite in 0.5 M ammonium nitrate solution (pH approximate to 5) and exhibits a good reproducibility and stability. The catalytic peak current was found to be linear with the nitrite concentration in the range 0.5-100 mM, with a correlation coefficient of 0.9998, using linear sweep voltammetry. The mechanism and kinetics of the catalytic oxidation of nitrite reaction were investigated using cyclic voltammetry, rotating disk electrode (RDE) voltammetry and chronoamperometry. The results were explained using the theory of electrocatalytic reactions at chemically modified electrodes. The value of second order rate constant (k') for a cross-exchange reaction between nitrite and redox sites in the modifier evaluated by the above approaches is about 2 x 10(-2) cm s(-1). (C) 2004 Elsevier B.V. All rights reserved.