Synthetic Metals 151 (2005) 208–210 Volumetric measurement of hydrogen storage in HCl-treated polyaniline and polypyrrole Barbara Panella a,∗ , Lina Kossykh b , Ursula Dettlaff-Weglikowska b , Michael Hirscher a , Giuseppe Zerbi c , Siegmar Roth b a Max-Planck-Institut f¨ ur Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany b Max-Planck-Institut f¨ ur Festk¨ orperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany c Politechnico di Milano, Dipartimento di Chimica, Piazza L. da Vinci 32, I-20133 Milano, Italy Received 25 October 2004; accepted 12 May 2005 Available online 23 June 2005 Abstract Inspired by very promising results of 6–8 wt.% hydrogen storage in conducting polymers claimed in recent years, we reproduced very carefully these experiments comprising chemical treatment of these materials and hydrogen uptake measurements. However, our results show clearly that no hydrogen storage is measured for HCl-treated polyaniline and polypirrole, neither at room temperature nor at 77 K. © 2005 Elsevier B.V. All rights reserved. Keywords: Conducting polymers; Polyaniline; Polypyrrole; Hydrogen storage; Volumetric measurement In August 2002 at the 224th ACS National Meeting in Boston researchers form the Korea Institute of Energy Research in Taejon reported a potential breakthrough, describing that cheap conducting polymers, polyaniline (PAni) and polypyrrole (PPy), can be used as hydrogen storage media [1]. Cho et al. showed very promising results of 6–8 wt.% hydrogen storage after treating the polymers with HCl. Since this first notification, conducting polymers are worldwide discussed as new potential hydrogen storage materials, e.g., Hydrogen Storage Think Tank Report of the US DoE of March 2003 [2]. Encouraged by these reports, we tried to reproduce the experiments of Cho et al. by following precisely the instructions for sample preparation and performing hydrogen sorption measurements with con- ditions as close as possible to theirs. In addition, adsorption measurements at liquid nitrogen temperature have been performed and compared to results obtained for activated carbon. ∗ Corresponding author. Tel.: +49 711 6891810; fax: +49 711 6891952. E-mail address: bpanella@mf.mpg.de (B. Panella). As Cho et al., we have purchased PAni and PPy from Sigma–Aldrich Co. PAni was delivered as powder of emeral- dine salt. The PPy was obtained from a 5 wt.% solution in water after evaporating the water, since the material used by Cho et al., i.e., PPy coated on polyurethane core resin with polymer/urethane ratio of 4, was no longer available at Sigma–Aldrich Co. For the acid treatment, samples of 500 mg were slurred in 15 ml of 37% HCl and stirred at room temperature for 24 h. The suspension of PAni and PPy in hydrochloric acid was filtered using polycarbonate mem- brane filter, rinsed with deionised water and dried in the oven at 360 K for 24 h. The fine powder was first pressed into a compact pellet of 12 mm diameter using a press with a pressure of about 220 MPa. The pellet was then crushed to particles of approximately 2 mm in size for the measurement of hydrogen storage. The porosity of the untreated and treated PAni powder was measured recording N 2 adsorption isotherms at 77 K. Due to the HCl treatment, the BET specific surface area of the PAni sample increased from 8 to 23 m 2 /g. These values could be attributed in both cases to the mesoporosity of the samples, 0379-6779/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.synthmet.2005.05.004