SURFACE SEGREGATION EFFECTS OF THE ELECTRODES OF BINARY ALLOYS WITH ELECTROLYTE SOLUTIONS (EXPERIMENTAL RESULTES AND THEIR MODEL DESCRIPTION)тезисы доклада
Дата последнего поиска статьи во внешних источниках: 10 августа 2018 г.
Место издания:Federal Agency for Scientific Organizations Russian Academy of Sciences G.A. Krestov Institute of Solution Chemistry of Russian Academy of Sciences
Первая страница:5
Последняя страница:7
Аннотация:The current literature provides abundant results on the electrical double layer structure on electrodes of liquid alloys (first of all, alloys of Ga with Tl, In, Pb, Cd and certain other metals). At the same time, until very recently, the respective results on the double layer structure of solid alloys were either absent or highly contradictory. As was shown in our studies, this gap can be compensated by using the method of electrochemical measurements on electrodes of solid alloys the surface of which is periodically renewed by mechanically cutting off thin metal layers. By the impedance technique, the double layer capacitances were measured on renewed electrodes of Sn-Pb [1], Ag-Sn [2], Ag-Cd [3], Au-Ag [4] and Ag-Bi [5] in surface inactive electrolytes. These studies revealed a number of general effects, which accompany the formation of the equilibrium interface of a binary alloy with electrolyte solution. Thus, it was shown, that upon mechanical renewal (leveling of the bulk and surface compositions of the metal phase), in the range of ideal polarizability of electrodes, relaxation effects can be observed, which correspond to a nonfaradaic process of surface composition variations. These effects evidence that one of the alloy components proceeds at rates that can be considered as “anomalously fast” for solid-state processes. Using phenomenological models of the electrode-solution interface structure, the procedures for calculating the kinetics of electrode surface composition changes upon the renewal are developed. A comparison of the calculation results with experimental data shows that kinetics and mechanism of electrode surface enrichment with the surface-active component of the alloy are determined by the electrochemical parameters of the interface (potential difference, electrode charge, electrolyte composition, etc.) and phase characteristics of the studied alloy. The results of studying the effect of segregation at the alloy/electrolyte interface are compared with the data obtained by Auger spectroscopy and XPS at the interface of these alloys with vacuum.
The study is financially supported by the RFBR, grant № 15-03-05243.