In situ hybrid Nafion/SiO2-P2O5 proton conductors for high-temperature and low-humidity proton exchange membrane fuel cells

A proton-conducting membrane demonstrating excellent proton conductivity at high-temperature/low-humidity conditions as well as at fully hydrated states is an urgent demand for proton exchange membrane fuel cells (PEMFC). In this study, in a bid to achieve this goal, we develop a new hybrid membrane, which is based on incorporating SiO2-P2O5 glass electrolytes into hydrophilic channels of Nafion115 by in situ sol-gel synthesis of tetraethoxysilane (TEOS) and trimethylphosphate (TMP). The effect of SiO2-P2O5 content on the morphology, state of water, and water uptake of the hybrid membranes is quantitatively identified. Not only the well-connected/enlarged hydrophilic channels but also the increase in the number of free/bound water molecules is observed in the hybrid membranes. These interesting features are expected to enable the hybrid membranes to present the higher proton conductivity than the pristine Nafion115, which becomes more noticeable at high-temperature/low-humidity conditions.