TiO2/KNbO3 nanocomposite for enhanced humidity sensing performance

TiO2/KNbO3 nanocomposite was prepared by a two-step hydrothermal method. Impedance-type sensors based on TiO2/KNbO3, TiO2, and KNbO3, were fabricated by aerosol deposition method. The humidity sensing prop-erties were investigated in a relative humidity range of 11-95%. Our results reveal that the TiO2/KNbO3-based sensor shows a large impedance change over 5 orders of magnitude, which is 1-2 orders of magnitude larger than that of TiO2- and KNbO3-based sensors. A fast response time of 3 s and a relatively long recovery time of 163 s were obtained for the TiO2/KNbO3-based sensor. The boosted humidity sensing performance of the TiO2/KNbO3 nanocomposite is believed to be due to the combined effect of the heterojunction at the TiO2/KNbO3 interface and the Grotthuss mechanism. This work underscores that the two-step hydrothermal method would be a powerful method for fabricating high-purity nanocomposites with excellent humidity sensing performance.