Abstract

Polypyrrole (Ppy) nanowires are electrochemically synthesized using the nanochannels of a proton-modified natural zeolite clinoptilolite (HNZ). The synthetic inorganic structures Y zeolite and clay montmorillonite (M) in acid form (HY and HM) are also employed for pyrrole polymerization. The generation of Ppy with electrochemical activity is favored in a strongly acidic nanoscaled environment, in comparison with the polymer synthesized in the hosts without previous proton modification. It is proposed that the reduction/oxidation responses are a consequence of the polymer protonation/deprotonation where the H+ ions possibly act as charge transfer promoters. The well defined redox signals of Ppy included in HNZ, compared to the HY and HM, suggest that the polymeric units are held more tightly to the channels walls due to its complex framework. The TEM image of HNZ-Ppy reveals the presence of the polymer nanowires inside the natural zeolite framework. It is also found that the one electron oxidation process do not depend on first order monomer concentration but lower (0.38) for Ppy growth in HNZ, which is related to the spatial restriction of the host. (C) 2004 Elsevier Ltd. All rights reserved.