Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11011595 | International Journal of Hydrogen Energy | 2018 | 14 Pages |
Abstract
The introduction of naturally occurring fibrillary structured halloysite clays (HNTs) into the Nafion matrix resulted in an enhanced proton conductivity and a reduced activation energy for proton transport. To assess the effect of the various states of the HNTs as a membrane additive, the ÏH+ of the composite membranes (Nafion/HNTs, Nafion/HNTs-NH2, Nafion/HNTs-SO3H) was measured at 30 °C and 80 °C and at different levels of relative humidity (%RH). An overall improvement of the ÏH+ of the Nafion was observed in the presence of the nanotubular additives (HNTs or HNTs-NH2) which can be attributed to the high specific surface area accommodating hydrophilic functional groups and therefore contributing to the water retention/management in the composite membrane. However, the Nafion/HNT-SO3H composites are distinguished in terms of enhanced performance in ÏH+ which persist in the whole range of % RH levels and noted that the ÏH+ values are almost 2 times higher than native Nafion in the low humidity region (30%-50%) and at 80 °C. In agreement with the ÏH+ enhancement, the activation energy is lower than that of native Nafion indicating that the proton transport is facilitated in the presence of -SO3H modified HNTs, probably due to an improved connectivity and arrangement of ionic conducting domains.
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Authors
Ibtissam Ressam, Abdelkrim El Kadib, Mohammed Lahcini, Gerrit A. Luinstra, Hubert Perrot, Ozlem Sel,