Sensors and Actuators B 114 (2006) 263–267 Nanocomposite of Pd–polyaniline as a selective methanol sensor Anjali A. Athawale ∗ , S.V. Bhagwat, Prachi P. Katre Department of Chemistry, University of Pune, Pune 411007, India Received 19 October 2004; received in revised form 24 May 2005; accepted 25 May 2005 Available online 1 July 2005 Abstract Palladium nanoparticles were obtained by a reflux method. A Pd–polyaniline nanocomposite was synthesized by oxidative polymerization of a 0.1 M aniline (stabilizer) solution containing palladium nanoparticles. The synthesized nanocomposite was subjected to different aliphatic alcohol vapours such as methanol, ethanol and isopropanol. The results showed that the nanocomposite was highly selective and sensitive to methanol vapours. The sensor responded rapidly and reversibly in the presence of methanol vapours. The selectivity of the nanocomposite was further investigated by exposing it to mixtures of methanol–ethanol and methanol–isopropanol. The nanocomposite is found to exhibit exactly identical response to that for pure methanol except for the response time. The sensing mechanism has been explained on the basis of FT-IR spectroscopy. © 2005 Elsevier B.V. All rights reserved. Keywords: Pd nanoparticles; Reflux; Pd–polyaniline nanocomposite; Sensor 1. Introduction Nanotechnology has been the thrust area of research, which requires the development of novel engineered mate- rials that can be successfully integrated into the exist- ing technology. The synthesis and selective application of such engineered materials are of critical importance for the development of functional nanodevices. Nanocomposites of metal–polymer or metal oxide–polymer are expected to be an important class of materials in the area of nanotechnology [1]. These novel materials possess electronic and optical proper- ties, which are distinctly different from those of individual nanoparticles. Tailor-made nanocomposites exhibiting a new class of properties can be synthesized by careful selection and appropriate combination of both components. Moreover, these materials can be used for the applications such as print- ing, spraying and spin coating, etc. [2]. Practical applications are foreseeable in optical and electronic chemical sensing [3–11], nanoscale electronics and catalysis [12,13]. ∗ Corresponding author. Tel.: +91 20 25601229; fax: +91 20 25691728. E-mail address: agbed@chem.unipune.ernet.in (A.A. Athawale). In the present paper, a Pd–polyaniline (Pd–Pani) nanocomposite has been utilized as a sensing material for various alcohol vapours. The results related to their sensitiv- ity and selectivity have been discussed extensively. 2. Experimental All the chemicals (aniline, methanol, ethanol, isopropanol and hexane) used were of A.R. grade and distilled before use. Ammonium persulphate was used as received. Pd nanoparticles were synthesized by a thermal reflux method. The reaction mixture (100 ml) containing 1 × 10 -3 M PdCl 2 ·5H 2 O and 0.1 M aniline (stabilizer) with methanol–water (1:1.5) as a solvent was refluxed for 3 h at a temperature of 50 ◦ C. Ammonium persulphate was used as an oxidizing agent for the preparation of the nanocompos- ite. Further, details about the synthesis of nanocomposite are reported earlier [14]. Blank polyaniline (Pani) was also synthesized by adopting the procedure as described above in the absence of palladium in the reaction mixture. 0925-4005/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2005.05.009