Journal of Power Sources 160 (2006) 940–948 Electrocatalytic properties of monometallic and bimetallic nanoparticles-incorporated polypyrrole films for electro-oxidation of methanol V. Selvaraj a , M. Alagar a,∗ , I. Hamerton b a Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025, India b Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom Received 11 December 2005; accepted 16 February 2006 Available online 6 June 2006 Abstract Oxidative electrochemical polymerization of pyrrole at indium-doped tin oxide (ITO) is accomplished from a neat monomer solution with a supporting electrolyte (0.3 M n-tetrabutyl ammonium tetrafluoroborate) by multiple-scan cyclic voltammetry. Polypyrrole (Ppy) films containing nanometer-sized platinum and Pt/Pd bimetallic particles are electro-synthesized on ITO glass plates by voltammetric cycling between -0.1 and +1 V (versus Ag/AgCl/3 M NaCl). The electrocatalytic oxidation of methanol on the nanoparticle-modified polypyrrole films is studied by means of electrochemical techniques. The modified electrode exhibits significant eletrocatalytic activity for methanol oxidation. The enhanced electrocatalytic activities may be due to the uniform dispersion of nanoparticles in the polypyrrole film and a synergistic effect of the highly- dispersed metal particles so that the polypyrrole film reduces electrode poisoning by adsorbed CO species. The monometallic (Pt) and bimetallic (Pt/Pd) nanoparticles are uniformly dispersed in polypyrrole matrixes, as confirmed by scanning electron microscopic and atomic force microscopic analysis. Energy dispersive X-ray analysis is used to characterize the composition of metal present in the nanoparticle-modified electrodes. © 2006 Elsevier B.V. All rights reserved. Keywords: Electrocatalytic activity; Methanol oxidation; Polypyrrole; Platinum nanoparticles; Platinum/palladium bimetallic nanoparticles; Fuel cell 1. Introduction There is increasing interest in the electro-oxidation of methanol because of the development of direct methanol fuel cells (DMFCs) as power sources for electric vehicles and elec- tronic devices. The DMFC is a promising future technology as an alternative to conventional energy-generating devices due to its higher energy-conversion efficiency, low-to-zero pollutant emis- sions, ready availability of methanol fuel, ease in distribution, and high energy [1]. Platinum is used in such fuel cells on the basis of its activity for methanol oxidation. There is, however, a particular difficulty, namely, the poisoning of anode catalysts by adsorbed carbonyl species that are derived from methanol oxi- dation. To improve the catalytic performance and to decrease the poisoning effect of the anode catalyst, composite catalytic sys- ∗ Corresponding author. Tel.: +91 44 22351323; fax: +91 44 22352870. E-mail address: mkalagar@yahoo.com (M. Alagar). tems such as Pt/Ru [2,3] and Pt/WO 3 [4] have been investigated. An alternative approach is the dispersion of precious metals such as Pt, Ru, Au and Pd on to a conducting matrix such as carbon or graphite. Such electrodes are not easy to fabricate due to the high carbon/graphite concentrations that are required for con- ductivity. To overcome such difficulties, conducting polymers have been used as a substrate for the incorporation of metal par- ticles. These systems present a new and novel class of electrode materials. Conducting polymers offer great advantages over other mate- rials since they are permeable to electroactive species, readily modified by different techniques, and easy to coat on various substrates. The polymers possess high electronic conductivity and a porous structure, which can accommodate a dispersed cat- alyst with a large surface area that is necessary for efficient elec- trocatalysis. Conducting polymers with porous structures and high surface areas, such as polyaniline and polypyrrole (Ppy), are usually employed as matrix to incorporate noble metal catalysts for the electro-oxidation of small molecules such as hydrogen, 0378-7753/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2006.02.055