Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the ...Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetry (TG). The experimental results indicated that AACH and amorphous A1OOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume (2.175 cm^3/g), high surface area (237.8 m^2/g), and low bulk density (0.284 g/mL).展开更多
The hydrothermal reaction of Na2MoO4 . 2H(2)O, V2O5 and en in water gave rise to a graphite-shaped vanadate [H3O](2)V3O8 1, which is doped with molybdenum. Compound 1 crystallizes in tetragonal system, space group P4b...The hydrothermal reaction of Na2MoO4 . 2H(2)O, V2O5 and en in water gave rise to a graphite-shaped vanadate [H3O](2)V3O8 1, which is doped with molybdenum. Compound 1 crystallizes in tetragonal system, space group P4bm, H6O10V2.9Mo0.1, M-r = 323.37, a = 8.904(1), c = 5.573(1)Angstrom, V = 441.8(1)Angstrom (3), Z = 2, D-c = 2.431 g.cm(-3), mu = 3.137 mm(-1), F(000) = 314, the final R = 0.0477, wR = 0.0993 for 260 observed reflections. Its two-dimensional framework is built up by corner-shared ((VO4)-O-V) tetrahedra and ((VO5)-O-IV) square pyramids with all of the terminal oxygen atoms toward the same orientation and further connected inta three-dimensional framework through hydrogen bonding between the protoned water molecules.展开更多
Iron oxides, including α-Fe2O3, γ-Fe2O3, Fe3O4, etc. are one of the most widely investigated materials for their fundamental properties and potential applications. One-dimensional (1-D) iron oxides nanostructures ...Iron oxides, including α-Fe2O3, γ-Fe2O3, Fe3O4, etc. are one of the most widely investigated materials for their fundamental properties and potential applications. One-dimensional (1-D) iron oxides nanostructures are the focus of recent research activi- ties because of their wide applications in magnetic refrigeration, information storage, electronics, catalysts, Li-ion battery, pigment, gas sensors, etc. This review covers the recent progress in the synthesis, properties and applications of 1-D iron oxides nanostructures. The paper begins with the introduction to 1-D iron oxides nanostructures, followed by the typical synthetic methods developed for the synthesis of 1-D iron oxides nanostructures. Then, the typical 1-D iron oxides nanostructures, in- cluding nanowires/nanorods, nanotubes, nanobelts, nanochalns, and special 3-D structures built on 1-D building blocks, are introduced in detail. The properties of 1-D iron oxides nanostructures are then discussed, focusing on the magnetic, gas sensing, and electrochemical and photocatalytic properties. Finally, we draw conclusions and look at the prospects of 1-D iron oxides nanostructures.展开更多
Porous tetragonal BaTiO 3 ceramic was successfully prepared by a combination of hydrothermal and low-temperature-sintering method.The hollow TiO2@BaCO 3 as the sintering precursor was synthesized via a simple hydrothe...Porous tetragonal BaTiO 3 ceramic was successfully prepared by a combination of hydrothermal and low-temperature-sintering method.The hollow TiO2@BaCO 3 as the sintering precursor was synthesized via a simple hydrothermal method,and then porous BaTiO 3 was generated by calcining the hollow TiO2@BaCO 3 precursor at 900 ℃ without additive.The hollow TiO2@BaCO 3 structure plays two important roles in the preparing of the porous BaTiO 3 ceramic.First,the TiO2@BaCO 3 hollow structure provides high surface areas and increases the contact points between BaCO 3 and TiO2,which can reduce the sintering temperature of the BaTiO 3 ceramic.Second,the cavity of the ordered arranged TiO2@BaCO 3 hollow sphere shows important influence on the porous structure,and the pore size of the as-prepared porous BaTiO 3 ceramic can be tuned from several nanometers to hundreds nanomters by changing the sintering temperature.The formation mechanism of the porous BaTiO 3 ceramic was proposed.展开更多
The adsorption and dissociation of CH3OH on TiO2 (110) were studied using density functional theory methods. Our results suggest that CH3OH molecules can adsorb up to 3/4 ML (1 ML=5.2× 10^14 molecules/cm2) co...The adsorption and dissociation of CH3OH on TiO2 (110) were studied using density functional theory methods. Our results suggest that CH3OH molecules can adsorb up to 3/4 ML (1 ML=5.2× 10^14 molecules/cm2) coverage at five-coordinated titanium (Tisc) sites to form the first layer. In the second layer, the CH3OH is adsorbed at bridge-bonded oxygen, and from the third layer, the CH3OH molecules form a hydrogen-bonded network with each other. The theoretical results show that dissociation of multilayer adsorbed methanol to aldehyde occurs through a stepwise pathway, with easy O-H bond dissociation and rate-determining C-H bond dissociation. The dissociation barriers for 8 or 12 CH3OH molecules on TiO2 are higher than that for low coverage by 0.15-0.21 eV; this suggests that the dissociation of multilayer adsorbed CH3OH is harder.展开更多
基金the financial support by the Natural Science Foundation of Liaoning Province of China (Grant No. 2013020122)the National Natural Science Foundationof China (Grant No. 21076100 and 51308045)the financial support by the PetroChina Company Limited (Grant No. 10-01A-01-01-01)
文摘Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetry (TG). The experimental results indicated that AACH and amorphous A1OOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume (2.175 cm^3/g), high surface area (237.8 m^2/g), and low bulk density (0.284 g/mL).
基金the State Education Ministry the State Personal Ministry+1 种基金 National Natural Science Foundation of China (20073048) the NSF of Fujian and the Chinese Academy of Sciences.
文摘The hydrothermal reaction of Na2MoO4 . 2H(2)O, V2O5 and en in water gave rise to a graphite-shaped vanadate [H3O](2)V3O8 1, which is doped with molybdenum. Compound 1 crystallizes in tetragonal system, space group P4bm, H6O10V2.9Mo0.1, M-r = 323.37, a = 8.904(1), c = 5.573(1)Angstrom, V = 441.8(1)Angstrom (3), Z = 2, D-c = 2.431 g.cm(-3), mu = 3.137 mm(-1), F(000) = 314, the final R = 0.0477, wR = 0.0993 for 260 observed reflections. Its two-dimensional framework is built up by corner-shared ((VO4)-O-V) tetrahedra and ((VO5)-O-IV) square pyramids with all of the terminal oxygen atoms toward the same orientation and further connected inta three-dimensional framework through hydrogen bonding between the protoned water molecules.
基金supported by the National Natural Science Foundation of China (Grant No. 51002059)the National Basic Research Program of China (Grant No. 2011CBA00700)+2 种基金the Natural Science Foundation of Hubei Province (Grant No. 2009CDB326)the Research Fund for the Doctoral Program of Higher Education (Grant Nos. 20090142120059, 20100142120053)the Director Fund of WNLO. Special thanks to the Analysis and Testing Center of HUST
文摘Iron oxides, including α-Fe2O3, γ-Fe2O3, Fe3O4, etc. are one of the most widely investigated materials for their fundamental properties and potential applications. One-dimensional (1-D) iron oxides nanostructures are the focus of recent research activi- ties because of their wide applications in magnetic refrigeration, information storage, electronics, catalysts, Li-ion battery, pigment, gas sensors, etc. This review covers the recent progress in the synthesis, properties and applications of 1-D iron oxides nanostructures. The paper begins with the introduction to 1-D iron oxides nanostructures, followed by the typical synthetic methods developed for the synthesis of 1-D iron oxides nanostructures. Then, the typical 1-D iron oxides nanostructures, in- cluding nanowires/nanorods, nanotubes, nanobelts, nanochalns, and special 3-D structures built on 1-D building blocks, are introduced in detail. The properties of 1-D iron oxides nanostructures are then discussed, focusing on the magnetic, gas sensing, and electrochemical and photocatalytic properties. Finally, we draw conclusions and look at the prospects of 1-D iron oxides nanostructures.
基金supported by the National Natural Science Foundation of China (50972130,20701033,51172209,91122022)Zhejiang Environmental Protection Bureau Foundation (2011B19)China Postdoctoral Science Foundation (201003048)
文摘Porous tetragonal BaTiO 3 ceramic was successfully prepared by a combination of hydrothermal and low-temperature-sintering method.The hollow TiO2@BaCO 3 as the sintering precursor was synthesized via a simple hydrothermal method,and then porous BaTiO 3 was generated by calcining the hollow TiO2@BaCO 3 precursor at 900 ℃ without additive.The hollow TiO2@BaCO 3 structure plays two important roles in the preparing of the porous BaTiO 3 ceramic.First,the TiO2@BaCO 3 hollow structure provides high surface areas and increases the contact points between BaCO 3 and TiO2,which can reduce the sintering temperature of the BaTiO 3 ceramic.Second,the cavity of the ordered arranged TiO2@BaCO 3 hollow sphere shows important influence on the porous structure,and the pore size of the as-prepared porous BaTiO 3 ceramic can be tuned from several nanometers to hundreds nanomters by changing the sintering temperature.The formation mechanism of the porous BaTiO 3 ceramic was proposed.
基金financially supported by National Natural Science Foundation of China(21173212)the Key Research Program of the Chinese Academy of Sciences
文摘The adsorption and dissociation of CH3OH on TiO2 (110) were studied using density functional theory methods. Our results suggest that CH3OH molecules can adsorb up to 3/4 ML (1 ML=5.2× 10^14 molecules/cm2) coverage at five-coordinated titanium (Tisc) sites to form the first layer. In the second layer, the CH3OH is adsorbed at bridge-bonded oxygen, and from the third layer, the CH3OH molecules form a hydrogen-bonded network with each other. The theoretical results show that dissociation of multilayer adsorbed methanol to aldehyde occurs through a stepwise pathway, with easy O-H bond dissociation and rate-determining C-H bond dissociation. The dissociation barriers for 8 or 12 CH3OH molecules on TiO2 are higher than that for low coverage by 0.15-0.21 eV; this suggests that the dissociation of multilayer adsorbed CH3OH is harder.