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Pure phase of sillenite structure, Bi12TiO20, was directly synthesized using stoichiometric bismuth (III) nitrate pentahydrate and titanium glycolate by co-precipitation. The influence of pH on the structure of Bi12TiO20 was studied in the pH range of 3–10. The sillenite structure was characterized using XRD and FTIR. The photo-degradation reaction of 4-nitrophenol (4-NP) was used to study photocatalytic activity of Bi12TiO20 as a function of the preparation pH. The rate of decomposition was followed by UV-vis and TOC. The beginning concentration of 4-NP, 44 ppm, decreased to less than 1 ppm within 30 min for all prepared catalysts. It was found that the decomposition rate constant of Bi12TiO20 is six times higher than those of either TiO2 or Bi2O3 under the same conditions. 相似文献
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Muangjai Unruan Sujitra Unruan Yutthapong Inkong Rattikorn Yimnirun 《Journal of Electronic Materials》2017,46(11):6418-6421
This paper reports on an indirect measurement of energy density of soft PZT ceramic utilizing mechanical stress. The method works analogous to the Olsen cycle and allows for a large amount of electro-mechanical energy conversion. A maximum energy density of 350 kJ/m3/cycle was found under 0–312 MPa and 1–20 kV/cm of applied mechanical stress and electric field, respectively. The obtained result is substantially higher than the results reported in previous studies of PZT materials utilizing a direct piezoelectric effect. 相似文献
4.
Nuchnapa Tangboriboon Sujitra Wongkasemjit Ruksapong Kunanuruksapong Anuvat Sirivat 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(1):50-60
Calcium zeolite type A (CaNaAlSi2O7), called soda melilite, with a molar ratio of CaO:Al2O3:Na2O:SiO2 of 1:1:2:8 and calcined at 300 °C for 1 h was successfully synthesized by a sol–gel process using eggshell as the starting
material. The CaNaAlSi2O7 catalysts had N2 adsorption–desorption isotherms and good electrical properties. The specific surface area, pore volume, and average pore
diameter were 55.15 m2/g, 0.51, and 37.19 nm, respectively. The dielectric constant, electrical conductivity, and loss tangent are 46.5785, 5.2360 × 10−3 (Ω m)−1, and 2.75, respectively as measured at room temperature and at 1000 kHz (1 MHz). The transmission electron microscopy (TEM)
images showed a moderately good dispersion of uniform particles with an average diameter of about 0.5 nm. X-ray diffraction
patterns (XRD), Fourier transform infrared spectra, and simultaneous thermal analysis data (STA) were obtained to confirm
the synthesis products. 相似文献
5.
Pattarasuda Naknam Apanee Luengnaruemitchai Sujitra Wongkasemjit 《International Journal of Hydrogen Energy》2009
Preferential CO oxidation in a H2-rich stream was studied over Au/ZnO and Au/ZnO–Fe2O3 catalysts prepared by photodeposition under UV–vis light. The high catalytic activities of both Au/ZnO and Au/ZnO–Fe2O3 catalysts are presented over a temperature range of 30–130 °C. TEM results revealed that the average particle size of Au over the Au/ZnO and Au/ZnO–Fe2O3 catalysts, is in the range of 3–5 nm. Moreover, DR/UV–vis spectra showed that the prepared catalysts contained Auδ+ and Au0 (active sites for the PROX reaction) on the catalyst support. Based on the experiment observations, it can be concluded that the catalysts prepared by a photodeposition exhibited excellent catalytic activity, even when both CO2 and H2O were added to the simulated stream. 相似文献
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Kanchana Utchariyajit Sujitra Wongkasemjit 《Microporous and mesoporous materials》2008,114(1-3):175-184
A new route for preparation of mesoporous AlPO4-5 (AFI) zeotype has been synthesized using alumatrane precursor, prepared from aluminum hydroxide and triisopropanolamine (TIS) by the oxide one pot synthesis (OOPS), via microwave technique using triethylamine (TEA) as a structure-directing agent. The influences of the reaction mixture composition, HF acid, water content and the crystallization temperature and time were investigated. The prepared materials were characterized using X-ray diffraction, SEM and BET. The results showed a mesoporous AlPO4-5 zeotype having a uniform rod-like structure with surface area around 120–180 m2/g. The high crystallinity with narrow size distribution of crystals was obtained at a high amount of structure-directing agent (the mole ratio of TEA/Al2O3 = 3.5). The presence of fluorine ion retarded the nucleation and growth rate, leading to a bigger crystal size. The crystal of the AFI grew preferentially in the c-direction with the reaction time and the water content. The use of lower reaction temperature to obtain good crystalline material can be compensated by a longer reaction time. 相似文献
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Srisin Eaimsumang Sujitra Wongkasemjit Sangobtip Pongstabodee Siwaporn Meejoo Smith Sukritthira Ratanawilai Nuwong Chollacoop Apanee Luengnaruemitchai 《中国稀土学报(英文版)》2019,37(8):819-828
Ceria(CeO_2)supports,synthesized by hydrothermal treatment with different synthesis time(CeO_2-X h,where X is the synthesis time in h)in the presence of the surfactant cetyltrimethyl ammonium bromide,were used as supports for gold(Au)catalysts.The synthesis time significantly affects the morphological structure and crystallite size of CeO_2,where CeO_2-2 h has the smallest crystallite size with coexisting nanorods and nanoparticles.Transmission electron microscopy analysis confirms the morphology of CeO_2 with distinctive(110),(100)and(111)planes,in agreement with interplanar spacings of 0.19,0,27 and 0.31,respectively.However,the morphology of CeO_2-8 h and CeO_2-48 h is mainly a truncated octahedral with crystal planes(111)and(100)accompanied by an interplanar spacing of 0.31 and0.27 nm,respectively.The CeO_2-X h supports and those with a 3 wt%Au loading(Au/CeO_2-X h)were investigated in the oxidative steam reforming of methanol at temperatures between 200 and 400 ℃.The Au/CeO_2-2 h gave the highest methanol conversion level and hydrogen yield at a low temperature of 250 ℃.This superior catalytic performance results from the good interaction between the metal and support and the well-distributed Au species on the CeO_2 support. 相似文献
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Ruethaithip Wisedsri Thanyalak Chaisuwan Sujitra Wongkasemjit 《Materials Letters》2011,65(21-22):3237-3240
Hierarchical architecture of cubic sillenite bismuth titanate (Bi12TiO20) is successfully synthesized using simple ethylene glycol-mediated self-assembly; followed by calcination under air at 600 °C for 30 min. The products are characterized using field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA), and X-ray diffraction (XRD). The reaction time has an effect on the product morphology, which changed from a leaf- and circular plate-like structure to a completely formed hierarchical structure within 2 h. The hierarchical structure of Bi12TiO20, having a size around 3 μm, is composed of 2D twist nanoplates, and each twist nanoplate has a thickness around 10–30 nm. 相似文献
9.
David W. Hatchett Nicole M. Millick John M. Kinyanjui Sujitra Pookpanratana Marcus Bär Timo Hofmann Alessio Luinetti Clemens Heske 《Electrochimica acta》2011,(17):6060
The controlled uptake and electrochemical reduction of metal precursors PdCl42− and PdCl62− in polyaniline (PANI) is demonstrated. The formation of PANI/Pd composites is achieved with a reduction in proton doping and an increase in the oxidation of the polymer with Pd deposits physically blocking the nitrogen groups. High surface area filaments (PdCl42−) or a rough encapsulation (PdCl62−) of Pd metal on PANI are obtained. The structural differences highlight the influence of the metal precursor oxidation state on the morphology of the Pd deposits in PANI. Thermal gravimetric analysis provides an estimate of the Pd content for each composite of ∼40%. X-ray Photoelectron Spectroscopy and X-ray-excited Auger Electron Spectroscopy analyses confirm the deposition of Pd metal. The catalytic oxidation of methanol was demonstrated for both PANI/Pd composites in alkaline solutions that prohibit proton doping of the polymer. The data indicates that Pd metal acts as a solid-state dopant that may delocalize the charge on the polymer backbone to maintain conductivity. Methanol oxidation at PANI/Pd composites produced using PdCl42− was enhanced relative to the composite produced using PdCl62− and a planar Pd electrode. Comparison of PANI/Pd composite produced using PdCl42− with other Pd catalysts from the literature indicates surface poisoning is reduced when Pd is coupled with the polymer. The composite is robust and stable in alkaline solution with the charge density decreasing by 5% on the positive scan and 13% on the negative scan after 200 voltammetric cycles. The data also indicates that the reductive desorption of surface contaminants is possible, minimizing the catalytic loss due to surface poisoning. 相似文献
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A series of bimetallic Fe–Ti-MCM-48 materials was successfully synthesized via sol–gel method using cetyltrimethylammonium bromide (CTAB) as a template and silatrane, iron (III) chloride, and titanium (IV) isopropoxide as silica, iron, and titanium sources, respectively. Scanning electron microscopy (SEM) showed the truncated octahedron morphology of Fe–Ti-MCM-48.X-ray diffraction (XRD) patterns showed well-defined, order cubic mesoporous structures. X-ray fluorescence (XRF) revealed the total metal content of the final product. UV–visible absorption spectra confirmed both iron (Fe3+) and cerium (Ti4+) species highly dispersed in the framework, while N2 adsorption/desorption measurements indicated a high specific surface area. As metal content increased, the mesoporous order and surface area decreased. The synthesized Fe–Ti-MCM-48 with 0.01Fe/Si and 0.01Ti/Si ratio still retained a cubic structure after hydrothermal treatment at 100 °C for 72 h. 相似文献