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Xiang Q.,Wuhan University of Technology | Lv K.,Wuhan University of Technology | Lv K.,Key Laboratory of Catalysis and Materials Science | Yu J.,Wuhan University of Technology
Applied Catalysis B: Environmental | Year: 2010

Surface-fluorinated anatase TiO2 nanosheets with dominant {0 0 1} facets were fabricated by a simple hydrothermal route in a Ti(OC4H9)4-HF-H2O mixed solution. The atomic ratios of fluorine to titanium (RF) exhibit an obvious influence on the structures and photocatalytic activity of TiO2 samples. In the presence of HF, TiO2 nanosheets can be easily obtained. With increasing RF, the relative anatase crystallinity, average crystallite size, pore size and percentage of exposed {0 0 1} facets increase, contrarily, BET specific surface areas decrease. All fluorinated TiO2 nanosheets exhibit much higher photocatalytic activity than Degussa P-25 TiO2 (P25) and pure TiO2 nanoparticles prepared in pure water due to the synergistic effect of surface fluorination and exposed {0 0 1} facets on the photoactivity of TiO2. Especially, at RF = 1, the fluorinated TiO2 nanosheet exhibits the highest photocatalytic activity, and its photoactivity exceeds that of P25 by a factor of more than nine times. © 2010 Elsevier B.V. All rights reserved. Source

Yang H.,Shanxi University | Ma Z.,Shanxi University | Qing Y.,Jiangsu Polytechnic University | Xie G.,Key Laboratory of Catalysis and Materials Science | And 3 more authors.
Applied Catalysis A: General | Year: 2010

A new periodic mesoporous hybrid material with a built-in Pd-guanidine complex was synthesized in the presence of a structure-directing agent. The N2 sorption, XRD and TEM characterizations revealed that this hybrid material had a large surface area (>700 m2 g-1), a narrow pore size distribution (centered at 2.7 nm), and a periodic 2D-hexagonal structure. FT-IR, solid state NMR and XPS investigations confirmed that palladium-guanidine complex was covalently integrated with the solid material. The solid material exhibited high activity for the Suzuki coupling reaction of various aryl bromides in an aqueous ethanol solution under air. Furthermore, it was found that the solid material worked well for the aerobic oxidation of benzylic alcohols under ambient pressure of O2, affording over 99% selectivity. This catalyst could be reused 9 times without a decrease in selectivity. This study supplies a new periodic mesoporous hybrid material with a built-in active palladium sites, which may be applied to other catalytic reactions. Crown Copyright © 2010. Source

Tang D.,Wuhan University of Technology | Tang D.,Key Laboratory of Catalysis and Materials Science | Zhao W.,Wuhan University of Technology | Cheng S.,Wuhan University of Technology | Zhang Q.,Wuhan University of Technology
AIP Conference Proceedings | Year: 2012

β-Zn4Sb3 is a promising candidate thermoelectric material with extraordinary low lattice thermal conductivity and high dimensionless figure of merit. In the paper, X-ray diffraction (XRD) patterns and X-ray photoelectron spectra (XPS) of In-doped β-Zn4Sb 3 compounds with nominal composition Zn4Sb 3-mInm (0≤m≤0.18) were investigated to reveal the effect of indium doping on crystal structure and binding characteristics. The Rietveld refinement based on the XRD data indicates that the indium impurity preferentially occupies the 12c Sb(2) site in Zn4Sb 3-mInm. The lattice parameter a increases and c decreases with the increasing m, accompanying with the lattice distortion and the bond length and angle modification. Indium doping enhances the occupancies of Zn atoms at the 36f Zn(1) and interstitial Zn sites, whereas the total occupancy of Sb and In atoms maintains constant. XPS analysis shows that the valence of Sb decreases and that of Zn increases with increasing the indium doping in Zn 4Sb3-mInm. This implies that the negative charge might transfer from In and Zn to Sb atoms. Curve-fittings of Sb 3d photoelectron peaks prove that only the Sb atom at the 12c Sb(2) site is charged to more negative with the increasing m. Thus more Zn2+ ions near the 12c Sb(2) site are needed to maintain the charge balance, which is why the occupancy of electropositive Zn increases in the compound. The asymmetric Sb-In ionic bond forms by the In substituting Sb at the 12c Sb(2) site, which changes the vibration behavior of Sb-Sb dimer and leads to more dynamical disorders of the localized dumbbell vibrations in β-Zn4Sb3. These new lattice disorders in β-Zn4Sb3, introduced by the substitution of In for Sb, result in a much low lattice thermal conductivity of 0.49 W·m-1·K-1 of Zn4Sb 2.96In0.04. © 2012 American Institute of Physics. Source

Yang H.-J.,Key Laboratory of Catalysis and Materials Science | Yang H.-J.,South-Central University for Nationalities | Wang W.,Key Laboratory of Catalysis and Materials Science | Wang W.,South-Central University for Nationalities
Journal of Chemical and Engineering Data | Year: 2010

The end groups of bis(2-hydroxyethyl) ether (compound 1) and tetraethylene glycol (compound 2) were modified by ethyl oxalyl chloride to produce two new compounds: oxalic acid 2-(2-ethoxy-oxalyloxy-ethoxy)-ethyl ester ethyl ester (compound 3) and oxalic acid 2-{2-[2-(2-ethoxyoxalyloxyethoxy)-ethoxy]-ethoxy}- ethyl ester ethyl ester (compound 4). Then, the solubility of compounds 1 to 4 were investigated and compared in supercritical carbon dioxide at a temperature range of (313 to 333) K and in the pressure range of (9.1 to 19.6) MPa. The effect of the end group and molecular weight for the solubility of the compounds were discussed. In addition, the tested solubility data were then calculated and correlated with the semiempirical model at different pressures and temperatures, which showed satisfactory agreement with each other, and the average absolute relative deviation was in the range of (0.07 to 13.82) %. © 2010 American Chemical Society. Source

Jin J.,Key Laboratory of Catalysis and Materials Science | Jin J.,South-Central University for Nationalities | Yang H.-J.,Key Laboratory of Catalysis and Materials Science | Zhang N.,Key Laboratory of Catalysis and Materials Science | Chang F.,University of Shanghai for Science and Technology
Fluid Phase Equilibria | Year: 2012

In present study, five new CO 2-philic 1-methypropanedioate derivatives containing nonfluorous alkyl groups had been designed and synthesized. The solubilities of these compounds in supercritical carbon dioxide (scCO 2) were investigated with a static analytical method at the temperature from 323K to 343K and in the pressure range of 9.3-13.7MPa. All compounds showed high solubilities in supercritical CO 2 at easily accessible temperatures and pressures. To correlate the experimental data, two density-based models proposed by Bartle and Chrastil were investigated. The correlation results showed good self-consistency between the calculated and the measured values, which were in the range of 7.79-21.99% by Bartle model and 4.09-11.15% by Chrastil model. Additionally, according to the Kumar and Johnston theory, the partial molar volume V̄2 of each compound in scCO 2 was also calculated and the results were between -10788.4 and -1585.84. © 2012 Elsevier B.V. Source

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