Gas sensitivity of heterojunction TiO2NT/GO materials prepared by a simple method with low-concentration acetone

Abstract

Graphene oxide (GO) was prepared using a modified Hummers' method, and titanium dioxide nanotubes (TiO2NT) were prepared by a hydrothermal method. The gas sensing material (graphene oxide-titanium dioxide nanotubes) was obtained by self-assembling composite GO and TiO2NT.Then the material was coated onto a gold electrode to prepare the device. This resultant device exhibits excellent response to low concentrations of acetone and high selectivity over other gases. Through SEM test analysis, TiO2NT was tiled on a sheet of GO to form a physically bonded heterojunction semiconductor composite. XRD analysis confirms that the anatase TiO2 was successfully produced and there was no impurity peak in the composite. During the gas sensing test, it was proved that the device exhibited an excellent response to 0.3 ppm of acetone at 250 °C. The heterojunction material still exhibits the resistance characteristics of the n-type semiconductor, and the material resistance is reduced in a gas environment by carrier conduction. The increase of sensitivity arises from the fact that the holes of GO and the carriers of TiO2NT are moved towards each other to form a space charge region, which causes the material to form a larger resistance difference in the test gas environment.