Investigation of reduced graphene oxide and Nb-doped TiO2 nanotube hybrid structure to improve gas sensing response and selectivity

The precise detection of flammable and explosive gases and vapors remains an important issue due to the increasing demand for renewable energy sources and safety requirements in industrial process. Metal oxides (TiO2, SnO2, ZnO, etc.) are very attractive materials for the manufacturing of chemical gas sensors. However, their gas selectivity issues and further improvement of sensing response remain a significant challenge. Incorporation of metal oxides with two-dimensional (2D) graphene oxide (GO) is considered as a promising approach to obtain hybrid structures with improved gas sensing performance. Herein, we report the development of GO and niobium-doped titanium dioxide nanotubes (NTs) hybrid structures with tunable selectivity and sensing response against hydrogen gas, achieved by properly controlling the reduction degree and concentration of GO. The effects of these parameters are systematically studied in terms of response amplitude and selectivity. It was found that, compared to undoped titanium dioxide nanotubes, the hybrid material with an optimal concentration of reduced-GO and the introduction of niobium shows an increase in hydrogen response of about an order of magnitude and a simultaneous reduction of the response to possible interfering compounds such as carbon monoxide and acetone, thus providing enhanced selectivity. This research may provide an efficient way to enhance the chemical sensing performance of metal oxide nanomaterials.