Proton conductivity in tungsten and antimony-modified titania ceramics prepared by the sol–gel method

Titania ceramic materials modified with 5% antimony and 5% tungsten were prepared by the sol–gel method. For the antimony-modified material, a treatment with H2O2 was also performed, in order to obtain antimonic acid. The electric conductivity of the xerogels was measured at 25 °C in the relative humidity (RH) range 33–81%. At 25 °C, the electrical conductivity of the “as prepared” 5% Sb ceramic varies from 2.02×10−5 S cm−1 at 33% RH to 1.12×10−2 S cm−1 at 81% R.H. For the material treated with H2O2, the conductivity varies from 1.56×10−5 to 2.37×10−2 S cm−1 for 33% and 81% R.H., respectively. For the tungsten-modified material, the conductivity varies from 1.02×10−5 to 2.66×10−3 S cm−1 for 33% and 81% R.H., respectively. The activation energies observed for proton conduction were 23.5 kJ mol−1 for TiO2/W 5%, 22.9 kJ mol−1 for TiO2/Sb 5% and 20.6 kJ mol−1 for the material treated with H2O2. The highest activation energy was observed for untreated TiO2:24.8 kJ mol−1. nductivity values for the Sb-modified ceramics are superior to those reported previously for antimonic acid films, and approach the values reported for proton-conducting polymers, such as Nafion®, making them a potential candidate for application as electrolytes in fuel cell systems.