Proton Conduction in Porous Silica Glasses with High Water Content

Abstract

Silica glasses with high surface area were prepared by the sol−gel method, the electrical conductivity of which was measured as a function of the content of adsorbed water. The glasses obtained by heating at 400−800 °C had specific surface areas of 700−900 m2/g glass and exhibited room-temperature conductivities of 10-6−10-3 S/cm by absorbing the water in pores. The activation energy for conduction linearly decreased with increasing logarithm of the product of proton and water concentration. On the other hand, the increase in conductivity was represented to be proportional to the logarithm of water concentration. Electrical conduction in glasses containing a large amount of water is related to the dissociation of protons from the SiOH bonds and the proton hopping through water molecules in pores.