Effect of thermal treatment on conductometric response of hydrogen gas sensors integrated with HCl-doped polyaniline nanofibers

Abstract

In this work, we investigated the effect of thermal treatments on the transduction of HCl-doped polyaniline (PANI) nanofibers integrated in conductometric devices upon exposure to 1% H2 (carried by N 2). After drying in N2 at ∼25 C for 12 h, our devices showed a ∼10% decrease in electrical resistance upon exposure to 1% H 2. However, devices subject to 12-h drying in N2 at ∼25 C followed by further thermal treatments in N2 at 100 C, 164 C or 200 C for 30 min showed different transduction behaviors. The devices subject to thermal treatments at 100 C and 164 C showed a ∼7% decrease and <0.5% variation in electrical resistance, respectively. More interestingly, the device subject to the thermal treatment at 200 C showed a transduction behavior with obvious opposite polarity, i.e. a ∼5% increase in electrical resistance upon exposure to 1% H2. Further analysis indicated that the observed results were related to the thermal treatments which caused HCl-doped PANI nanofibers to undergo (i) water desorption, (ii) crosslinking and/or (iii) partial carbonization. © 2014 Elsevier B.V. All rights reserved.