Arvydas Survila

Abstract:

A systematic quantitative description of the main stages of the electrochemical process involving metal complexes is presented, and methods for taking into account the role of chemical stages are proposed. The generalized model of mass transfer of chemically interacting particles is based on a system of differential equations containing both diffusion and kinetic terms [1]. The total surface concentration of metal-containing species can be determined at any kinetics of chemical steps using the convolution of current transients. Surface distribution of individual species depends on the degree of system liability. It serves as the basis for determining the surface concentrations that are used further in the analysis of the charge transfer kinetics. Based on the congruence of voltammograms and plots of potentiometric titration, the features of the processes occurring in labile systems are revealed. These are: development of cathodic pre-waves, anodic pseudo-limiting currents, double current maxima, etc. Methods for determining the composition of the electrochemically active complex (EAC) are substantiated taking into account the specificity of complex systems. Kinetic equations of direct and consecutive charge transfer are analyzed with their further transformation into Tafel plots normalized with respect to the EAC surface concentration. Prospects for extension of theoretical developments to other systems, in particular, to the processes of hydrogen evolution involving ligands as proton donors, are considered.