Polyaniline-silica nanocomposite: Application in electrocatalysis of acetylthiocholine

Abstract

Electropolymerization of aniline is reported within nano-structured network of organically modified sol-gel glass (ORMOSIL) matrix. Three important redox mediators viz., tetracyanoquinodimethane (TCNQ), tetrathiafulvalene (TTF) and ferrocene were encapsulated within ormosil film at the surface of indium tin oxide (ITO) electrodes and used for electropolymerization of aniline. In order to study the effect of electrocatalyst together with the redox-mediator during the electropolymerization of aniline, palladium was also introduced within nano-structured network of ormosils. Polyaniline (PAni) with excellent electrochemical behavior was grown within these modified electrodes and the process of electropolymerization was found as a function of redox mediators' characteristics. The presence of palladium within ormosil matrix dramatically altered the electropolymerization process and the electrochemistry of PAni as well. The resulting polymers were analyzed by cyclic voltammetry and scanning electron microscopy and the results again provided remarkable dependence on the property of redox mediators and palladium content justifying similar conclusion. The polyaniline obtained as PAni-TCNQ and PAni-TCNQ-Pd composites has been utilized for fabricating the modified electrodes to study the electrochemical sensing of acetylthiocholine. The results based on cyclic voltammetry and amperometry justify that the electrode material exhibit excellent electrocatalytic activity for the oxidation of acetylthiocholine with major findings as compared to control: (1) acetylthiocholine undergo direct oxidation with considerable increase in both anodic and cathodic peak currents and (5) an increase in the sensitivity of acetylthiocholine analysis to the order of 5 fold for the modified electrodes.