Electrode kinetics of the O2/O2- redox couple at Hg electrode in the presence of PVC in aprotic media

The kinetic and thermodynamic parameters of the O-2/O-2(-) redox couple at a mercury electrode in various aprotic solvents have been evaluated by normal pulse polarography and cyclic voltammetry in the presence of poly(vinyl chloride) (PVC) as a maximum suppressor. The polarographic maxima were observed on the rising portion of polarogram for O-2 reduction, but they are completely suppressed by the addition of a small amount of PVC. The adsorption behavior of PVC on a hanging mercury drop electrode is examined based on the measurement of the differential capacitance of the electrical double layer. The relevant kinetic and thermodynamic parameters, i.e., the standard rate constant, k degrees, the cathodic transfer coefficient, alpha(c), and the formal potential, E degrees' of the O-2/O-2(-) redox couple were estimated together with the diffusion coefficients of O-2, D-o2. An excellent linear relationship between the formal potential and solvent's acceptor number was found. (C) 2005 Elsevier Ltd. All rights reserved.