Low-dimensional Materials Synthesis, Characterization And Gas Adsorption Properties Of Study

SnO2 nanorods are fabricated via a novel and simple hydrothermal synthetic route with cetyltrimethyl ammonium bromide (CTAB) as a template-directed reagent. This method adopted in our thesis overmatched the previous synthetic routes. For instance, the reactive was accomplished only at 160°C, which dramaticly increase the experimental convenience. The structure and purity of SnO2 were characterized by X-ray diffraction (XRD), and the morphology of the nanorods were confirmed by scanning electron microscopy (SEM), indicating the as-prepared nanorods are tetragonal, and the diameter is ca. 40-100 nm in and up to 2-3 μm in length. Selected-area electron diffraction (SAED) confirmed that SnO2 nanorods are polycrystalline. Moreover, the size of nanorods changes with the concentration of the precursor SnCl4. We also fabricate dysprosium hydroxide by means of the similar method. In this procedure, Polyethylene glycol (PEG) acst as a template-directed reagent and the reaction was finished at 180°C under the hydrothermal condition. Compared with previous synthetic approach, these rare earth compound nanostructures were obtained from relatively moderate condition, and the synthetic process is easy to control. Subsequent calcinations of Dy(OH)3 at 450°C for 6 h led to Dy2O3 nanotubes. The samples' structure and morphology was characterized by XRD,SEM,transmission electron microscopy (TEM),select-area electron diffraction (SAED),high-resolution transmission electron microscopy (HRTEM). Results indicate that Dy(OH)3 and Dy2O3 are hexagonal and cubic structure, respectively. The outer diameter is from 60 nm to 185 nm, the inner diameter from 20 nm to 75 nm and the length up to 2-3 μm. Dy2O3 still preserves tube-like morphology after the calcinations of Dy(OH)3 nanotubes. SAED and HRTEM further confirmed that the samples are single-crystal. Then, we studied the gas adsorption properties of Dy(OH)3 and Dy2O3 nanotubes in ambient gases, such as NH3 NO2 C2H5OH C3H6O2. Their electric resistance has obviously variation. From the response and recover time, the two samples also have good gas selectivity. Further, the sensitivities to oxidizing gases are superior to reducing gases. By means of measuring the surface resistance of the CeO2 nanoparticles film, we roughly discussed the undoped CeO2 nanoparticles film's sensitivity to NH3 and NO2. Before discussion, the effect of humility on the film was eliminated by a successive thermal cycles. Then, we investigated that the temperature dependence of gas sensitivities for CeO2 thin film in NH3 and NO2. Results indicated that the film's sensitivity to NO2 at room is obviously higher than to NH3. Besides, sensitivity curves also present the good selectivity to the temperature.