Proton Conductivities of Titanium Phosphate at High Temperature for PEMFC

Titanium phosphate was synthesized fiom tetra iso‐propoxide (TTIP, Aldrich) and H3PO4 with a Ti/P molar ratio of 1:9 by sol gel method. A maximum proton conductivity value of 5.4 x 102 S.cm−1 at 20°C and 93% relative humidity (RH) was achieved. The high proton conductivity is related to the existence of the hydrogen bonding in POH groups and the water molecules in the gel structure which was confirmed by thermo gravimetric analysis (TGA). The conductivity increased with relative humidity, indicating that the Grotthuss was the main proton transport mechanism. Moreover, the proton conductivity increased with the temperature with the value of ∼10−1 S.cm−1at 200°C and 0.5% RH. The presence of water molecules and an excess of phosphoric acid in the gel matrix, which were confirmed by TGA and FTIR analysis, contributed to high proton conductivity at high temperature and low humidiity.