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Hexagonal WO_3 nanorods were synthesized through a facile hydrothermal method. The nanorods properties were investigated by scanning electron microscope(SEM), transmission electron microscope(TEM), energy dispersive spectroscopy(EDS), and x-ray diffraction(XRD). The NO_2-sensing performances in terms of sensor response, response/recovery times and repeatability at room temperature were optimized by varying the heat treatment temperature of WO_3 nanorods. The optimized NO_2sensor(400-℃-annealed WO_3 nanorods) showed an ultra-high sensor response of 3.2 and short response time of 1 s to 5-ppm NO_2. In addition, the 400-℃-annealed sample exhibited more stable repeatability.Furthermore, dynamic responses measurements of annealed samples showed that all the annealed WO_3 nanorods sensors presented p-type behaviors. We suppose the p-type behavior of the WO_3 nanorods sensor to be that an inversion layer is formed in the space charge layer when the sensor is exposed to NO_2 at room temperature.Therefore, the 400-℃-annealed WO_3 nanorods sensor is one of the most energy conservation candidates to detect NO_2 at room temperature.
Hexagonal WO_3 nanorods were synthesized through a facile hydrothermal method. The nanorods properties were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), and x-ray diffraction sensing performances in terms of sensor response, response / recovery times and repeatability at room temperature were optimized by varying the heat treatment temperature of WO_3 nanorods. The optimized NO_2sensor (400- ° C -analedaled WO_3 nanorods) showed an ultra-high sensor response of 3.2 and short response time of 1 s to 5-ppm NO 2. In addition, the 400- ° C -analyzed sample exhibited more stable repeatability. More Thermo measurements of annealed samples showed that all the annealed WO_3 nanorods sensors presented p-type behaviors. We suppose the p-type behavior of the WO_3 nanorods sensor to be that an inversion layer is formed in the space charge layer when the sensor is exposed to NO_2 at room te mperature.Therefore, the 400- ° C -analyzed WO_3 nanorods sensor is one of the most energy conservation candidates to detect NO_2 at room temperature.