Hydrogen sensing in titanate nanotubes associated with modulation in protonic conduction

Hydrogen/sodium titanate nanotubes (TNTs) were investigated as hydrogen (H(2)) sensors. TNT films exhibit good sensing properties and a large response, in particular at room temperature. Electrical conductivity measurements performed under different atmospheres from 25 to 300 °C indicate that, for T > 100 °C, conduction is thermally activated and can be attributed to electronic transport, whereas for T < 100 °C conduction is dominated by protonic transport. The T dependence of the H(2) sensitivity was determined and related to this variation in the dominant transport mechanism. For low T, H(2) sensing originates from the modulation in protonic conduction. Such modulation was attributed to the creation/destruction of surface hydroxyl groups.