采用溶胶 -凝胶法制得 Si O2 胶体 ,并将其与锐钛型 Ti O2 微粒复合制得 Ti O2 / Si O2 催化剂 .用透射电镜 (TEM)观察表面形貌 ,用红外光谱 (IR)和 X-射线衍射 (XRD)表征其结构 .以敌敌畏溶液等为体系 ,考察了 Ti O2 / Si O2 的催化性...采用溶胶 -凝胶法制得 Si O2 胶体 ,并将其与锐钛型 Ti O2 微粒复合制得 Ti O2 / Si O2 催化剂 .用透射电镜 (TEM)观察表面形貌 ,用红外光谱 (IR)和 X-射线衍射 (XRD)表征其结构 .以敌敌畏溶液等为体系 ,考察了 Ti O2 / Si O2 的催化性能 ,同时与单一的锐钛型 Ti O2 作对比 .结果表明 ,Ti O2 / Si O2 具有比 Ti O2展开更多
In this article, we report the preparation of a three-dimensional（3D） interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional（2D） hexagonal mes...In this article, we report the preparation of a three-dimensional（3D） interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional（2D） hexagonal mesoporous anatase 70 TiO2-30 SiO2-950 nanocomposite（crystallized at 950 °C for 2 h） as a precursor, NaO H as an etchant of SiO2 via a ＂creating mesopores in the pore walls＂ approach. Our strategy adopts mild conditions of creating pores such as diluted NaO H solution, appropriate temperature and solid/liquid ratio, etc. aiming at ensuring the integrities of mesopores architecture and anatase nanocrystals. XRD, TEM and N2 sorption techniques have been used to systematically investigate the physico-chemical properties of the nanocomposites. The results show that the intrawall mesopores are highly dense and uniform（average pore size 3.6 nm）, and highly link the initial mesochannels in a 3D manner while retaining mesostructural integrity. There is no significant change to either crystallinity or size of the anatase nanocrystals before and after creating the intrawall mesopores. The photocatalytic degradation rates of rhodamine B（RhB, 0.303 min^–1） and methylene blue（MB, 0.757 min^–1） dyes on the resultant nanocomposite are very high, which are 5.1 and 5.3 times that of the precursor; even up to 16.5 and 24.1 times that of Degussa P25 photocatalyst, respectively. These results clearly demonstrate that the 3D interconnected mesopores structure plays an overwhelming role to the increments of activities. The 3D mesoporous anatase TiO2-SiO2 nanocomposite exhibits unexpected-high degradation activities to RhB and MB in the mesoporous metal oxide-based materials reported so far. Additionally, the nanocomposite is considerably stable and reusable. We believe that this method would pave the way for the preparation of other 3D highly interconnected mesoporous metal oxide-based materials with ultra-high performance.展开更多
The SiO2/TiO2 composite powders including mineral tourmaline powders (T/SiO2/TiO2) were prepared from a sol made by a two-step hydrolysis method, using metasilicate ester as precursor. The powders were characterized b...The SiO2/TiO2 composite powders including mineral tourmaline powders (T/SiO2/TiO2) were prepared from a sol made by a two-step hydrolysis method, using metasilicate ester as precursor. The powders were characterized by scanning electron microscopy (SEM). The photocatalytic activity of the sample was evaluated by the photocatalytic degradation of methyl orange. The effects of heat-treatment on the photocatalytic activity were discussed. It is found that the T/SiO2/TiO2 composite powders show higher photocatalytic activity when including 10% SiO2 and 4% tourmaline. Moreover, the photocatalytic mechanism of tourmaline on the powders was proposed.展开更多
Neodymium doping titania was loaded to silicon dioxide to prepare Nd/TiO2-SiO2 by sol-gel method and Nd/TiO2-SiO2 was characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transf...Neodymium doping titania was loaded to silicon dioxide to prepare Nd/TiO2-SiO2 by sol-gel method and Nd/TiO2-SiO2 was characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform-infrared spectroscopy （FT-IR） and diffuse reflectance spectra （DRS）. Photocatalytic activities of Nd/TiO2-SiO2 with different neodymium contents were evaluated by degradation of methyl orange. The light absorption of Nd/TiO2-SiO2 increased with increasing doping neodymium in a visible light range of 388-619 nm, and Nd doping was in favor of decreasing the recombination of photo-generated electrons with holes. Nd and SiO2 improved the photocatalytic activity of TiO2. The optimal molar fraction of Nd to Ti was 0.1%, and the optimum calcination temperature was 600 ℃. The highest degradation rate of methyl orange was 82.9% after irradiation for 1 h.展开更多
TiO2 and TiO2-SiO2 photocatalysts were prepared by sol-gel and supercritical CO2 fluid drying method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), etc. Their catalytic propertie...TiO2 and TiO2-SiO2 photocatalysts were prepared by sol-gel and supercritical CO2 fluid drying method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), etc. Their catalytic properties were tested through the photocatalytic degradation of phenol and aniline in wastewater. The results show that the developed fluidized photocatalytic reactor (FPR) and TiO2 catalyst had better performance in degrading pollutants as compared with slurry photocatalytic reactor (SPR) and commercial TiO2 catalyst. The composition and crystal form of TiO2-SiO2 composite oxide had obvious influence on catalytic effect and TiO2-SiO2 photocatalysts showed better catalytic activity and stability.展开更多
The nanometer particles of TiO_2 and TiO_2/SiO_2 oxides wereprepared by sol-gel supercritical fluid drying method. The propertiesof TiO_2 and TiO_2/SiO_2 were characterized by means of BET(Brunner-Emmett- Teller metho...The nanometer particles of TiO_2 and TiO_2/SiO_2 oxides wereprepared by sol-gel supercritical fluid drying method. The propertiesof TiO_2 and TiO_2/SiO_2 were characterized by means of BET(Brunner-Emmett- Teller method), TEM (transmission electronmicroscopy), SEM (scanning electron microscopy), XRD (X-ray diffrac-tion) and FTIR (Fourier transform-infrared) techniques. The effectsof different preparation route, prehydrolysis and non-prehydrolysis,on the properties of TiO_2/SiO_2 oxide were also examined.展开更多
Chemical solution route was used to synthesize Bi3.1La0.9Ti3O12 and CoFe2O4. Alternate CoFe2O4/Bi3.1La0.9Ti3O12 layers were deposited on Pt substrate （Pt/TiO2/SiO2/Si） by spin coating. X-ray diffraction and SEM （sc...Chemical solution route was used to synthesize Bi3.1La0.9Ti3O12 and CoFe2O4. Alternate CoFe2O4/Bi3.1La0.9Ti3O12 layers were deposited on Pt substrate （Pt/TiO2/SiO2/Si） by spin coating. X-ray diffraction and SEM （scanning electron microscopy） studies show composite-like polycrystalline films. Films were studied for leakage current, dielectric response, ferroelectric and ferromagnetic properties. Leakage current was low （〈 10^-8 A） in electric field below 120 kV/cm, and the dielectric response shows relaxation. Dielectric loss （tan 8） reduces 〈 3% at 10^6 Hz. Two and four layer structures showed room temperature FE （ferroelectric） and FM （ferromagnetic） responses with FE Pr （polarization） 〉 25℃/cm2 and ferromagnetic Mr （memory） 〉 52 emu/cm3. Co-existence of FE and FM can be attributed to stress due to different crystal structures of the material involved in composite film structure.展开更多
Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO2 nanocrystal...Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO2 nanocrystals into submicron clusters, coating of these clusters with a silica layer, thermal treatment to remove organic ligands and improve the crystallinity of the clusters, and finally removing silica to expose the mesoporous catalysts. With the help of the silica coating, the clusters not only maintain their small grain size but also keep their mesoporous structure after calcination at high temperatures （with BET surface area as high as 277 m2/g）. The etching of SiO2 also results in the clusters having high dispersity in water. We have been able to identify the optimal calcination temperature to produce TiO2 nanocrystal clusters that possess both high crystallinity and large surface area, and therefore show excellent catalytic efficiency in the decomposition of organic molecules under illumination by UV light. Convenient doping with nitrogen converts these nanocrystal clusters into active photocatalysts in both visible light and natural sunlight. The strategy of forming well-defined mesoporous clusters using nanocrystals promises a versatile and useful method for designing photocatalysts with enhanced activity and stability.展开更多
Inorganic silica-titania thin films with thicknesses 150 nm-200 nm are deposited on high purity and polished silicon wafer and silica glass substrates by sol-gel dipping process and are patterned by capillary force li...Inorganic silica-titania thin films with thicknesses 150 nm-200 nm are deposited on high purity and polished silicon wafer and silica glass substrates by sol-gel dipping process and are patterned by capillary force lithography technique. Subsequently grating structure is embossed in green stage. The patterned gel films are subjected to stepwise heat treatment to 500 ℃ and above in pure oxygen atmosphere in order to achieve major conversion of mixed-gel to oxide optical films which are characterized by Ellipsometry, Fourier transform infrared spectroscopy （FTIR） and atomic force microscopy （AFM） to optimize the fabrication parameters and to get perfectly matched film. Removal of organics and formation of perfectly inorganic silica-titania network at optimized heat treatment in controlled environment are ensured by FTIR spectral study. The difference in refractive indices between the substrate and coated film as developed waveguides for operating wavelength show the planar waveguide behavior of the films. calculated theoretically matches exactly with the （632.8 nm） and the measured optical properties展开更多
文摘采用溶胶 -凝胶法制得 Si O2 胶体 ,并将其与锐钛型 Ti O2 微粒复合制得 Ti O2 / Si O2 催化剂 .用透射电镜 (TEM)观察表面形貌 ,用红外光谱 (IR)和 X-射线衍射 (XRD)表征其结构 .以敌敌畏溶液等为体系 ,考察了 Ti O2 / Si O2 的催化性能 ,同时与单一的锐钛型 Ti O2 作对比 .结果表明 ,Ti O2 / Si O2 具有比 Ti O2
基金supported by the National Natural Science Foundation of China(21373056)the Science and Technology Commission of Shanghai Municipality(13DZ2275200)~~
文摘In this article, we report the preparation of a three-dimensional（3D） interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional（2D） hexagonal mesoporous anatase 70 TiO2-30 SiO2-950 nanocomposite（crystallized at 950 °C for 2 h） as a precursor, NaO H as an etchant of SiO2 via a ＂creating mesopores in the pore walls＂ approach. Our strategy adopts mild conditions of creating pores such as diluted NaO H solution, appropriate temperature and solid/liquid ratio, etc. aiming at ensuring the integrities of mesopores architecture and anatase nanocrystals. XRD, TEM and N2 sorption techniques have been used to systematically investigate the physico-chemical properties of the nanocomposites. The results show that the intrawall mesopores are highly dense and uniform（average pore size 3.6 nm）, and highly link the initial mesochannels in a 3D manner while retaining mesostructural integrity. There is no significant change to either crystallinity or size of the anatase nanocrystals before and after creating the intrawall mesopores. The photocatalytic degradation rates of rhodamine B（RhB, 0.303 min^–1） and methylene blue（MB, 0.757 min^–1） dyes on the resultant nanocomposite are very high, which are 5.1 and 5.3 times that of the precursor; even up to 16.5 and 24.1 times that of Degussa P25 photocatalyst, respectively. These results clearly demonstrate that the 3D interconnected mesopores structure plays an overwhelming role to the increments of activities. The 3D mesoporous anatase TiO2-SiO2 nanocomposite exhibits unexpected-high degradation activities to RhB and MB in the mesoporous metal oxide-based materials reported so far. Additionally, the nanocomposite is considerably stable and reusable. We believe that this method would pave the way for the preparation of other 3D highly interconnected mesoporous metal oxide-based materials with ultra-high performance.
基金Project(E2004000033) supported by the Natural Science Foundation of Hebei Province, China
文摘The SiO2/TiO2 composite powders including mineral tourmaline powders (T/SiO2/TiO2) were prepared from a sol made by a two-step hydrolysis method, using metasilicate ester as precursor. The powders were characterized by scanning electron microscopy (SEM). The photocatalytic activity of the sample was evaluated by the photocatalytic degradation of methyl orange. The effects of heat-treatment on the photocatalytic activity were discussed. It is found that the T/SiO2/TiO2 composite powders show higher photocatalytic activity when including 10% SiO2 and 4% tourmaline. Moreover, the photocatalytic mechanism of tourmaline on the powders was proposed.
基金Project(2009B010100001) supported by the Key Academic Program of the 3rd Phase "211 Project" of South China Agricultural University, ChinaProject(2007B030103019) supported by Guangdong Science and Technology Development Foundation, China
文摘Neodymium doping titania was loaded to silicon dioxide to prepare Nd/TiO2-SiO2 by sol-gel method and Nd/TiO2-SiO2 was characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform-infrared spectroscopy （FT-IR） and diffuse reflectance spectra （DRS）. Photocatalytic activities of Nd/TiO2-SiO2 with different neodymium contents were evaluated by degradation of methyl orange. The light absorption of Nd/TiO2-SiO2 increased with increasing doping neodymium in a visible light range of 388-619 nm, and Nd doping was in favor of decreasing the recombination of photo-generated electrons with holes. Nd and SiO2 improved the photocatalytic activity of TiO2. The optimal molar fraction of Nd to Ti was 0.1%, and the optimum calcination temperature was 600 ℃. The highest degradation rate of methyl orange was 82.9% after irradiation for 1 h.
文摘TiO2 and TiO2-SiO2 photocatalysts were prepared by sol-gel and supercritical CO2 fluid drying method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), etc. Their catalytic properties were tested through the photocatalytic degradation of phenol and aniline in wastewater. The results show that the developed fluidized photocatalytic reactor (FPR) and TiO2 catalyst had better performance in degrading pollutants as compared with slurry photocatalytic reactor (SPR) and commercial TiO2 catalyst. The composition and crystal form of TiO2-SiO2 composite oxide had obvious influence on catalytic effect and TiO2-SiO2 photocatalysts showed better catalytic activity and stability.
基金Supported by PetroChina Company Limited (990801-21-2).
文摘The nanometer particles of TiO_2 and TiO_2/SiO_2 oxides wereprepared by sol-gel supercritical fluid drying method. The propertiesof TiO_2 and TiO_2/SiO_2 were characterized by means of BET(Brunner-Emmett- Teller method), TEM (transmission electronmicroscopy), SEM (scanning electron microscopy), XRD (X-ray diffrac-tion) and FTIR (Fourier transform-infrared) techniques. The effectsof different preparation route, prehydrolysis and non-prehydrolysis,on the properties of TiO_2/SiO_2 oxide were also examined.
文摘Chemical solution route was used to synthesize Bi3.1La0.9Ti3O12 and CoFe2O4. Alternate CoFe2O4/Bi3.1La0.9Ti3O12 layers were deposited on Pt substrate （Pt/TiO2/SiO2/Si） by spin coating. X-ray diffraction and SEM （scanning electron microscopy） studies show composite-like polycrystalline films. Films were studied for leakage current, dielectric response, ferroelectric and ferromagnetic properties. Leakage current was low （〈 10^-8 A） in electric field below 120 kV/cm, and the dielectric response shows relaxation. Dielectric loss （tan 8） reduces 〈 3% at 10^6 Hz. Two and four layer structures showed room temperature FE （ferroelectric） and FM （ferromagnetic） responses with FE Pr （polarization） 〉 25℃/cm2 and ferromagnetic Mr （memory） 〉 52 emu/cm3. Co-existence of FE and FM can be attributed to stress due to different crystal structures of the material involved in composite film structure.
文摘Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO2 nanocrystals into submicron clusters, coating of these clusters with a silica layer, thermal treatment to remove organic ligands and improve the crystallinity of the clusters, and finally removing silica to expose the mesoporous catalysts. With the help of the silica coating, the clusters not only maintain their small grain size but also keep their mesoporous structure after calcination at high temperatures （with BET surface area as high as 277 m2/g）. The etching of SiO2 also results in the clusters having high dispersity in water. We have been able to identify the optimal calcination temperature to produce TiO2 nanocrystal clusters that possess both high crystallinity and large surface area, and therefore show excellent catalytic efficiency in the decomposition of organic molecules under illumination by UV light. Convenient doping with nitrogen converts these nanocrystal clusters into active photocatalysts in both visible light and natural sunlight. The strategy of forming well-defined mesoporous clusters using nanocrystals promises a versatile and useful method for designing photocatalysts with enhanced activity and stability.
文摘Inorganic silica-titania thin films with thicknesses 150 nm-200 nm are deposited on high purity and polished silicon wafer and silica glass substrates by sol-gel dipping process and are patterned by capillary force lithography technique. Subsequently grating structure is embossed in green stage. The patterned gel films are subjected to stepwise heat treatment to 500 ℃ and above in pure oxygen atmosphere in order to achieve major conversion of mixed-gel to oxide optical films which are characterized by Ellipsometry, Fourier transform infrared spectroscopy （FTIR） and atomic force microscopy （AFM） to optimize the fabrication parameters and to get perfectly matched film. Removal of organics and formation of perfectly inorganic silica-titania network at optimized heat treatment in controlled environment are ensured by FTIR spectral study. The difference in refractive indices between the substrate and coated film as developed waveguides for operating wavelength show the planar waveguide behavior of the films. calculated theoretically matches exactly with the （632.8 nm） and the measured optical properties
