Sol–gel hybrid membranes loaded with meso/macroporous SiO2, TiO2–P2O5 and SiO2–TiO2–P2O5 materials with high proton conductivity

• Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel.
• Depositions of hybrid solutions by spraying onto glass substrates were performed.
• Proton conductivity was evaluated as a function of composition and porous structure.

In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO2, TiO2–P2O5 and SiO2–TiO2–P2O5 meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m2/g (TiO2–P2O5) and 300 m2/g (SiO2–TiO2–P2O5). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion® at higher temperatures (120 °C) (2·10−2 S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure.

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