Enhanced NO2 gas sensing properties of ZnGa2O4-core/TiO2-shell nanowires

초록

ZnGa2O4-core/TiO2-shell nanowires were fabricated by a two step process comprising thermal evaporation of a mixture of ZnO and Ga2O3 powders and sputter-deposition of TiO2. Transmission electron microscopy and X-ray diffraction analyses revealed that the core of a typical core-shell nanobelt comprised a simple tetragonal-structured single crystal ZnGa2O4 and that the shell comprised a polycrystalline TiO2. Multiple networked ZnGa2O4-core/TiO2-shell nanowire sensors showed the sensitivity of 4.78% at a NO2 concentration of 10 ppm at 300 oC. This sensitivity value is more than ten times larger than that of bare ZnGa2O4 nanowire sensors at the same NO2 concentration. The enhancement in the sensitivity of ZnGa2O4 nanowires to NO2 gas by sheathing the nanowires with TiO2 can be accounted for based on the space-charge model.