Proton conduction properties of hydrous sulfated nano-titania synthesized by hydrolysis of titanyl sulfate

We investigated the electrical conductivity and electrochemical properties of hydrous sulfated nano-titania. The conductivity reached 0.1 S cm− 1 at 50 °C under a relative humidity of 80%. Diffuse reflectance FT-IR spectra suggest that bidentate sulfate coordination likely forms on the nano-titania surface, which in turn contributes to the electrical conduction. The conductivity depended on relative humidity. Using a hydrogen concentration cell, we found that the electromotive force (EMF) of the nano-titania was almost the same as the theoretical value. These results suggest that the main conduction mechanism is proton conduction on the surface of the titania nanoparticles with the aid of sulfonic acid groups bound to the surface of the oxide.

Research Highlights►The conductivity of hydrous sulfated nano-titania reached 0.1 S cm− 1 at 50 °C. ►The bidentate sulfate coordination likely contributes to the high conductivity. ►The proton transport number of hydrous sulfated nano-titania was almost unity.