论文部分内容阅读
Hexagonal WO3nanorods are fabricated by a facile hydrothermal process at 180?C using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3nanorods with diameters ranging from 100 nm–150 nm and lengths up to several micrometers are obtained at PH = 2.5and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3nanorod sensor are obtained by measuring the dynamic response to NO2with concentrations in the range 0.5 ppm–5 ppm and at working temperatures in the range 25?C–250?C. The obtained WO3nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2gas, the WO3nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50?C, whereas, it behaves as a p-type semiconductor below 50?C. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3nanorod at room temperature. This finding is useful for making new room temperature NO2sensors based on hexagonal WO3nanorods.
Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ° C using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3nanorods with diameter ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range of 0.5 ppm-5 ppm and at working temperatures in the range of 25 ° C-250 ° C. The obtained WO3nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2gas, the WO3nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 ° C, while, it behaves as a p-type semiconductor below 50 ° C. The origin of the n- to p -type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 senns based on hexagonal WO3 nanorods.