Electrochemically deposited crystalline thin film of polyaniline on nickel for redox reactions at positive potentials

Prasad, Rajendra K and Munichandraiah, N (2002) Electrochemically deposited crystalline thin film of polyaniline on nickel for redox reactions at positive potentials. In: Synthetic Metals, 130 (1). pp. 17-26.

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Abstract

Redox reactions which occur at positive potentials such as ferrous/ferric, hydroquinone/quinone, ferrocyanide/ferricyanide etc. in aqueous acidic electrolytes cannot be studied on non-platinum metals, for example, a Ni electrode. On the contrary, these reactions occur on polyaniline (PANI) modified Ni electrodes, as evidenced from cyclic voltammetry, amperometry and steady-state polarization experiments. Under identical experimental conditions of scan rate (v) and concentration (C), the peak current density (i(p)) values of Fe2+/Fe3+ redox reaction are greater on the PANI modified Ni than on Pt. Additionally, the peak potential separation (DeltaE(p)) of the voltammogram is lesser on the PANI modified Ni. With an increase in thickness of the PANI, DeltaE(p) increases suggesting that the redox reactions tend to depart from the reversibility. Scanning electron micrographs reveal the presence of a crystalline deposit of PANI on Ni when the thickness of PANI is about 0.08 mum. However, the PANI becomes amorphous and porous at higher thickness values. Raman spectroscopy and X-ray diffraction studies corroborate the observations made out of scanning electron microscopy. Higher catalytic activity of PANI is attributed to crystalline nature of PANI on Ni. Exchange current density and standard rate constant of Fe2+/Fe(3+)redox reaction are evaluated. (C) 2002 Published by Elsevier Science B.V.

Item Type:	Journal Article
Publication:	Synthetic Metals
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Polyaniline;Non-platinum metal;Ferrous/ferric;Exchange current density;Standard rate constant.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	20 Jul 2011 06:34
Last Modified:	20 Jul 2011 06:34
URI:	http://eprints.iisc.ac.in/id/eprint/39166

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