POLYPYRROLE DEPOSITION ON THE SURFACE OF Al87Ni8Y5 AMORPFOUS ALLOYS IN POTENTIODYNAMIC MODE

Abstract

Polypyrrole films were deposited on the surface both of the outer and contact sides of the Al87Ni8Y5 amorphous alloy electrodes by potentiodynamic oxidation of 0.1 M pyrrole in 0.5 M H2SO4 aqueous solution. It was found that the oxidation of pyrrole on Al87Ni8Y5 amorphous alloy electrodes occurs comparatively easy and already during the first cycle of potential scanning a nanofilm of polypyrrole is formed. The formation of polypyrrole film essentially accelerates during following cycles of potential scanning. Cyclic voltammogramms has been analyzed and the process of electrochemical oxidation of pyrrole and redox transformations of polypyrrole at these electrodes is described. It is shown that the difference in film topology is due to the surface topology of electrodes, which determines stability of surface oxide films on these surfaces. Studies of the electrode surface topology and also morphology, structure and composition of polypyrrole films produced on an amorphous alloy electrode were carried out using Fourier-transform infrared spectro¬sco¬py with attenuated total reflection (FTIR-ATR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It has been confirmed using FTIR analysis that the films deposited on the surface of the Al87Ni8Y5 electrodes corespond to polypyrrole which are in the form of hydrosulfate salt. The analysis of the received electron microscopy images shown that polypyrrole films produced both on the contact and outer sides of the working electrodes has developed surface topology, which depends on surface quality and nature of amorphizing additive in electrode alloy. In addition, it is likely that a significant number of aggregates of polypyrrole macromolecules are formed in the solution, which further play the role of electrodes, where the oxidation of the corresponding monomer from its aqueous solution takes place. The results of EDX microanalysis shown presence in the polymeric films of small amount of metal impurities (in the form of sulfates mainly), which formed in the result of the corrosion of working electrode.