Electrochemical oxidation of pyrrole on the surface of the amorphous alloy of Al87Ni8Y5 composition in the 0.5 M sulfate acid solution

Abstract

Polypyrrole films were deposited on the surface both of the outer and contact sides of the Al 87 Ni 8 Y 5 amorphous alloy electrodes by potentiodynamic oxidation of 0.25 M pyrrole in 0.5 M H 2 SO 4 aqueous solution. It is determined that already in the first anode cycle of potential scanning a nanofilm of polypyrrole is formed on Al 87 Ni 8 Y 5 amorphous alloy electrodes. The further pyrrole oxidation in potentiodynamic mode occurs easily and film of polypyrrole actively formed on the surface of the working electrode. 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 spectroscopy 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 Al 87 Ni 8 Y 5 electrodes corespond to polypyrrole which are in the form of hydrosulfate salt. The analysis of the received electron microscopy images shown that a 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. The peculiarity of pyrrole oxidation and redox transformations of deposited polypyrrole on the Al 87 Ni 8 Y 5 electrode is mainly due to the high concentration of pyrrole in the solution and to a lesser extent to the properties of the electrode surfaces and naturally formed oxide films. Electrochemical oxidation of pyrrole on the Al 87 Ni 8 Y5 electrode in the potentiodynamic mode accompanied by the formation of quasi-spherical nanoaggregates, which form a dense primary film of polypyrrole. The formed nanoaggregates in the following cycles of potential scanning act as peculiar polymer electrodes. Keywords: pyrrole, amorpfous alloys, electrochemical oxidation, polypirrole, structure.