Papers by Keyword: Microwave Hydrothermal Method

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Authors: Hui Qi, Jian Feng Huang, Li Yun Cao, Jian Peng Wu
Abstract: –Hierarchical flower–like CuS spheres have been synthesized by a facile microwave hydrothermal (MH) method using cetyltrimethylammonium bromide (CTAB) as the surfactant. The as–prepared CuS crystallites under different CTAB contents were characterized by X–ray diffraction (XRD), field–emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Results show that the CTAB–assisted CuS particles have hierarchical flower–like microstructures that were assembled by thin nanoflakes with thickness of 10~20 nm. The corresponding HRTEM images reveal that these nanoflakes are composed of many nanoparticles with average size of about 7 nm. Moreover, when increasing the CTAB contents from 0 g⁄mL to 0.02 g⁄mL, the as–prepared CuS particles were found to have better dispersion stability with decreased average sizes of the hierarchical flower–like spheres. Comparing with the bulk CuS particles, the related UV–vis absorption spectrum of the as–prepared crystallites exhibits an obvious red shift with the absorption peak at 739 nm.
Authors: Yin Hu, Dan Zhen Li, Guang Can Xiao, Yu Shao
Abstract: A CTAB-assisted microwave hydrothermal method was used to synthesize BiVO4 photocatalysts with different shapes. The obtained products were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-vis diffuse reflectance spectroscopy (DRS). The results showed that the monoclinic phase BiVO4 polyhedron was formed via a tetragonal zircon-type BiVO4 precursor. UV-vis diffuse reflectance spectra showed a great shift to longer wavelengths in the visible region for the monoclinic phase BiVO4 samples compared to the BiVO4 precursor. The photocatalytic activity of the sample was investigated for the liquid phase photocatalytic degradation of RhB under visible light irradiation (λ>420nm). The effects of different reaction times on the photocatalytic activity of BiVO4 had also been investigated, and the highest efficiency was observed when the sample was prepared at 140 °C for 30min.
Authors: Zhi Qin Chen, Shan Shan Luo, Xiang Liang Chen, Ze Hua Zhou, Wen Kui Li
Abstract: The different crystal (rutile, rutile-anntase-brookite, anatase, amorphous) titania were prepared by the hydrolysis of titanium tetrachloride (TiCl4) in the absence or presence of HCl or NaOH. The mixture solution was processed in microwave hydrothermal autoclave at 120oC for 1.5 h and then at 180oC for 1 h to precipitate titania. HCl acted as inhibitor, which could control the crystal and shape of the precipitate of titania. NaOH was used to adjust the pH to the required value. As a result, the mixture of rutile (majority), anatase and brookite (minor) was obtained from the aqueous TiCl4 solution without any addition, shuttle-like and well-dispersed nanocrystalline rutile appeared in the presence of HCl from the aqueous TiCl4-HCl solution. Single phase anatase was obtained in the presence of NaOH with pH=7, and when pH=9, the product was quite amorphous. The products were analyzed using XRD and TEM.
Authors: Dan Chen, Yang Li, Yun Guo
Abstract: The microwave hydrothermal method was applied in the synthesis of Ni0.5Zn0.5Fe2 O4 ferrite nanoparticle. X-ray diffraction (XRD), infrared spectroscopy (IR) were conducted to characterize the as-prepared samples. The experiment results revealed the as-prepared nanoparticle was 8.50-10.3 nm in size with various synthesis temperatures from 40-120°C, and synthesis temperature had effects on the magnetic and adsorption properties of Ni0.5Zn0.5Fe2 O4. The saturation magnetization values increased from 22.6 to 90.8 emu g-1 with synthesis temperature increasing. Moreover, synthesis temperature also influences the adsorption capacity of methyl orange (MO) on Ni0.5Zn0.5Fe2 O4. The as-prepared Ni0.5Zn0.5Fe2 O4 showed the highest adsorption capacity of MO in the current work when synthesis temperature was 80°C, which was contributed to the more adsorption site distributed on the nanoparticle.
Authors: Li Xiong Yin, Fei Fei Wang, Jian Feng Huang, Dan Wang, Jia Yin Li
Abstract: SnO2 nanocrystals were synthesized using SnCl4•5H2O and NH3•H2O as the main raw materials and distilled water as the solvent by microwave hydrothermal. Reaction temperature on the structure and photocatalytic activities of the SnO2 nanocrystals by microwave hydrothermal process was studied. The phase composition, morphologies and photocatalytic activities of the product were characterized by XRD (X-ray diffraction), SEM (scanning electron microscope), TEM (transmission electron microscope) and photochemical reaction instrument. Results show the crystalline and conglobation of the product have significant effect on its photocatalytic properties. The homogeneous low-agglomerated and well crystallined SnO2 nanocrystals prepared at 180 °C has good photocatalytic activities during photocatalytic degradation of RhB process.
Authors: Zhi Qin Chen, Wei Jun Zeng, Wen Kui Li, Ze Hua Zhou, Hong Ying Yu
Abstract: The synthesis of nanocrystalline pure anatase at low temperature and short time is not an easy achievement, as the synthetic processes generally lead to amorphous, moreover some processes normally require harsh reaction. Uniform nanocrystalline pure anatase has been obtained using tetrabutyl titanate and normal butyl alcohol under microwave irradiation condition at low temperature 120 °C for 3 h. This process simplication will lower production cost and make continuous process possible. It was revealed that the as-synthesized TiO2 products without any heat treatment were uniformly dispersed and granulous single-phase anatase, with the average grain size of 10 nm, by means of XRD and TEM.
Authors: Wen Xiang Ye, Quan Xin Zhu, Wan Qing Xiong, Jian Lei, Xue Hong Liao
Abstract: The CuS nanoparticles precursor have been synthesized by microwave irradiation, using copper nitrate and thioacetamide (TAA) as raw materials, dodecyl sodium sulfate as surfactants. After the precursor had being split with n-butyl lithium for 14 days, we synthesized w-doped copper sulfide nanoparticles with microwave hydrothermal method. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectra.
Authors: Fen Wang, Da Wei Liu, Jian Feng Zhu, Dong Li
Abstract: High purity ZrSiO4 powders were prepared using zirconium oxychloride and tetraethoxysilane as raw materials by the microwave hydrothermal (M-H) method, in which NaF was added as mineralizer to promote the crystallization of zircon. The results show that the microwave-hydrothermal method greatly reduces the starting crystallization temperature of ZrSiO4 powders to 160~200 °C in 30 minutes, the characteristics of the microwave hydrothermally synthesized powders are superior to that synthesized by conventional hydrothermal in stability, purity and morphologies. And the XRD analysis shows that all peaks of the former powders are abnormal broadness except the (200) and (220) peaks, and the crystallization of powders can be improved by adding seed crystals of ZrSiO4. The ZrSiO4 particles are disk-like platelets which are monocrystal and have a trend of Single crystal to polycrystalline transition. The synthesis mechanism of ZrSiO4 by microwave hydrothermal (M-H) process is discussed.
Authors: En Guo Wang
Abstract: YVO4:Eu3+ phosphors were prepared by microwave hydrothermal method in this work. YVO4:Eu3+ phosphors were probed by photoluminescence (PL), X-ray powder diffraction (XRD) and scanning electron microscope (SEM). The effects of different preparation conditions on the photoluminescence, the structure and the morphology of YVO4:Eu3+ phosphors were studied. The experiment results show that the pH value and the Eu3+ doping amount have some important effect on the photoluminescence and the morphology of YVO4:Eu3+phosphors.
Authors: Dan Chen, Xiao Long Ma, Yang Li
Abstract: A new magnetic Fe3O4/MO-intercalated-LDH composite has been synthesized by combination of Fe3O4, layered double hydroxide (LDH) and methyl orange (MO). Fe3O4/Zn2CrLDH and Fe3O4/MO-intercalated-LDH were obtained via two-step microwave hydrothermal and anion exchange method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and vibrating sample magnetometer (VSM) were conducted to characterize the as-prepared samples. The latter exhibited that basal spacing of Zn2Cr-LDH is 1.18 nm. The value of saturation magnetization (Ms) is 20.5 emu/g. In addition, the amounts of adsorbed MO reached 1.54 mmol/g. Therefore, the material shows several advantages for the removal of pollutants.
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