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

Abstract

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 H 2O 2 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 H 2O 2, 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 TiO 2/W 5%, 22.9 kJ mol −1 for TiO 2/Sb 5% and 20.6 kJ mol −1 for the material treated with H 2O 2. The highest activation energy was observed for untreated TiO 2:24.8 kJ mol −1. The conductivity 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.