ELECTROCHEMICAL PROPERTIES OF NOBLE METAL ALLOYS STUDIED BY CYCLIC VOLTAMMETRY

摘要

In this paper are summarized the results concerning studies on fundamental electrochemical properties of binary and ternary noble metal alloys in acidic solution.The systems were characterized electrochemically using cyclic voltammetry technique (CV).A CV curve can be treated as a basic mean of in situ surface analysis of electrodes of this type.The voltammogram recorded under given experimental conditions is characteristic of the individual noble metal or alloy and it is an electrochemical 'fingerprint' of the investigated sample.Qualitative and quantitative conclusions can be drawn about the surface state of noble metal alloys on the basis of the course of CV curves by the use of the distinctive features associated with each component.Such an analysis is possible due to the fact that the voltam-mograms for pure metals differ markedly from each other in respect of the region of surface oxide formation and its reduction as well as the appearance of the region where hydrogen electrosorption takes place.In particular,the potential of the oxygen desorption peak is a linear function of the alloy surface composition.The influence of the procedure of prolonged potential cycling on electrochemical behavior of the alloys is presented.During the electrochemical treatment the alloy surface becomes enriched with components that are more resistant to electrochemical dissolution,occurring at sufficiently high potentials.The course of the voltammogram undergoes dramatic changes concerning the signals originating from hydrogen and oxygen electrosorption.As a result of the procedure of potential cycling both alloy surface and bulk can become heterogeneous.Selective removal of alloy components during the electrochemical treatment allows for in situ preparation of alloy electrodes possessing a variety of electrocatalytic properties.