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1.
The synthesis and microstructure of morph-genetic TiC/C ceramics 总被引:1,自引:0,他引:1
Wood is a natural material with a novel and ordered hierarchical structure. In the present work, it is used as a bio-template to produce morph-genetic TiC/C ceramics. This is obtained by infiltrating the carbon preform pyrolyzed from wood with tetrabutyl titanate. It was subsequently sintered at 1400 °C to produce the final ceramic structure.By observing the microstructure under the scanning electron microscope and the transmission electron microscope, the morph-genetic TiC/C ceramics are shown retaining the complex morphology of the original template structure. The crystalline TiC was formed through the reaction of tetrabutyl titanate with carbon preform, and it was distributed mainly at the surface layer of the cellular wall. During the conversion of wood into carbon preform, the specific surface area of samples increased from 28.2 to 35.7 m2 g−1, and its porosity also increased from 64.4% to 80.3%. However, during the conversion of carbon preform into morph-genetic ceramics, the specific surface area of samples decreased from 35.7 to 33.8 m2 g−1, and its porosity also decreased from 80.3% to 76.5%. At the synthesis process, the variation of pore-size distribution is mainly in the range from 0.1 to 1 μm. 相似文献
2.
《塑料、橡胶和复合材料》2013,42(9):449-456
AbstractA series of waterborne polyurethane/inorganic (WPU/TiO2) hybrid composites were synthesised by a sol–gel process on the basis of isophorone diisocyanate, polyether polyol (GE-210), dimethylolpropionic acid, tetrabutyl titanate (TBT) and 3-glycidyloxypropyl trimethoxysilane as a coupling agent. The physical properties of the WPU and WPU/TiO2 dispersions and hybrids were measured. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and X-ray diffraction were used to assess the fracture surface morphology and the dispersions of the WPU/TiO2 hybrids. The scanning electron microscopy, transmission electron microscopy and atomic force microscopy results showed that the TiO2 particles were dispersed homogeneously in the WPU matrix in nanoscale. The prepared hybrids showed good thermal stability and mechanical properties in comparison with pure WPU and showed tunable transparence with the TBT fraction in the film. Through suitable adjustment of TBT content, some thin hybrids have potential applications, such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes. 相似文献
3.
In a mixed solvent of water and ethanol, polystyrene/titanium dioxide (PSt/TiO2) composite particles of core-shell structure were prepared by hydrolysis of tetrabutyl titanate in the presence of cationic PSt particles or anionic PSt particles surface-treated using γ-aminopropyl triethoxysilane. Hollow TiO2 particles were obtained through calcination of the PSt/TiO2 core-shell particles to burn off the PSt core or through dissolution of the core by tetrahydrofuran (THF). An alternative process constituted of preheating the PSt/TiO2 particles at 200°C to allow partial crystallization followed by calcination or PSt dissolution by THF. The outcome TiO2 particles thus prepared were examined by TEM, and hollow TiO2 particles were observed. The crystalline phase structure and phase transformation were characterized, which revealed that preheating before the removal of the PSt core was useful to achieve the desired hollow TiO2 particles, and the calcination process was beneficial to the formation of anatase and rutile structures. The tests of TiO2 particles as catalyst in the photodegradation of Rhodamine B demonstrated that a much higher catalytic activity was observed with the TiO2 hollow particles prepared through calcination combined with preheating. 相似文献
4.
Shichao Li Mengmeng Jiang Xue Shi Zuohua Liu Guowei Zhou 《Journal of Porous Materials》2017,24(6):1425-1436
In this study, hierarchical titanium dioxide (TiO2) microspheres with controlled morphology derived from calcination treatment of hierarchical titanate microspheres were fabricated. The obtained hierarchical TiO2 microspheres with diameters of 1 to 2 µm were composed of polycrystalline anatase nanosheets with thickness of 10 nm. The morphology was manipulated by simply adjusting the molar ratio of tetrabutyl titanate/P123. At a low molar ratio of 17.04, TiO2 microspheres composed of a large number of nanosheets closely packed together were obtained. At a high molar ratio of 34.08, TiO2 hybrid architectures with polycrystalline anatase hierarchical microspheres and single-crystal anatase mesoporous (approximately 5 nm) nanospheres were obtained. Investigations on evolution formation revealed that P123 played a key role in the formation of a well-defined hierarchical structure. The photocatalytic performances of the obtained samples were investigated by the degradation of methylene blue and papermaking wastewater. When compared with commercial P25, the obtained hierarchical TiO2 microspheres exhibit superior photocatalytic activity, high degradation efficiency, and good reproducibility. The product with hybrid architectures exhibited the highest photocatalytic activity. The chemical oxygen demand and the chroma removal rate of papermaking wastewater achieved 85.5 and 100%, respectively, after 12 h of photodegradation. 相似文献
5.
《Ceramics International》2017,43(12):8596-8602
Hollow TiO2 spheres were easily fabricated through a template-free solvothermal route only using tetrabutyl titanate (TBT) as raw material and absolute ethanol as solvent. The morphology of hollow TiO2 spheres was successfully controlled by adjusting the reaction time and reaction temperature. The formation process of hollow TiO2 spheres includes three steps based on the experimental results: the hydrolysis of TBT to produce Ti(OH)4 clusters in water formed from an ethanol etherification reaction under high temperature and high pressure, the assembly of Ti(OH)4 clusters into solid spheres, and the transformation of solid TiO2 spheres into hollow TiO2 spheres. Furthermore, the as-prepared hollow TiO2 spheres exhibited good thermal insulation performance including heat barrier and heat reflection. 相似文献
6.
《Carbon》2015
TiO2/reduced graphene oxide (RGO) nanocomposites Gx (RGO titania nanocomposite, x grams tetrabutyl titanate per 0.03 g RGO, x = 0.25, 0.50, 1.00) were prepared by a hydrothermal method: graphene oxide was reduced to RGO in a 2:1 water:ethanol mixture in the presence of varying quantities of tetrabutyl titanate, which deposited as TiO2 on the RGO sheets. The nanocomposites were characterized by a combination of Fourier transform infrared spectroscopy, diffuse reflectance ultraviolet–visible spectroscopy, photoluminescence spectroscopy, Raman spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy studies. The nanocomposite G0.25 exhibits enhanced nonlinear optical properties compared to its individual components, which is ascribed to a combination of mechanisms. The role of defects and electron/energy transfer in the optical limiting performance of G0.25 was clarified with the help of Raman and photoluminescence spectroscopies. Intensity-dependent switching between reverse saturable absorption and saturable absorption behavior was observed with the G0.50 nanocomposite. 相似文献
7.
A solvothermal process was developed to in situ prepare epoxy (EP)/TiO2 hybrid precursors. The chemical structure of samples was confirmed by X-ray and Fourier transformed infrared spectroscopy. Field emission scanning electron microscope micrographs of cured EP/TiO2 hybrid composites showed that well-dispersed TiO2 nanoparticles were successfully in situ formed in epoxy matrix through the solvothermal process. The thermogravimetic analysis, DSC, and gel content measurements showed that EP/TiO2 hybrid precursors were fully cured with the glass transition temperature decreasing gradually. The effect of TiO2 contents on optical and surface properties was investigated in detail. The results indicated that epoxy/TiO2 nanocomposites exhibited excellent UV shielding effect and high visible light transparency. The contact angle of EP/TiO2 nanocomposites, when the content of silane-coupling agent (KH560) was 5 g and the content of tetrabutyl titanate (TBT) was 3 g, can reach as high as 101°, which was 36° higher than that of pure EP, representing for the increase of hydrophobicity. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
8.
Yinglei Chen Baolin ZhuMeiyu Yao Shurong WangShoumin Zhang 《Catalysis communications》2010,11(12):1003-1007
Au@TiO2 core/shell nanoparticles were synthesized by a simple and efficient one-step method using tetrabutyl titanate as TiO2 precursor. The samples were characterized by TEM, XRD, UV–vis and XPS. The experiments demonstrated that the average particles size of Au was 10–15 nm, and the thickness of TiO2 shell was 1–3 nm. TiO2 shell induced a red-shift of the absorption peak of Au. This material exhibited catalytic activity for CO oxidation. This study offered an approach for CO oxidation by using Au@TiO2 model catalysts. 相似文献
9.
《Ceramics International》2015,41(7):8717-8722
Developing photocatalysts with specific morphology and good photocatalytic activities promises good opportunities to discover the geometry-dependent properties. In the present work, ring-like anatase TiO2 with dominant {001} facets exposed were successfully synthesized via a one-pot solvothermal process of tetrabutyl titanate and hydrofluoric acid solution at 180 °C for 8 h. We found that hydrofluoric acid plays an important role in the formation of ring-like TiO2. The morphology and microstructure were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller N2 gas adsorption–desorption isotherms. The photocatalytic activity was evaluated by photocatalytic oxidation degradation of methylene blue aqueous solution under UV light. Results showed that ring-like TiO2 with {001} facets exposed exhibited an excellent photocatalytic activities due to its unique structure: Nanosheets with hole. 相似文献
10.
A transparent spherical polymer matrix containing TiO2/SiO2 hybrid materials is prepared from the copolymerization reaction between TiO2/SiO2 hybrid materials containing vinyl groups and methyl methacrylate (MMA). Transparent TiO2/SiO2 hybrid materials are prepared from the reaction between nucleophilic agents and tetrabutyl titanate (TBT). Three reaction mechanisms leading to the formation of nanometer TiO2/SiO2 hybrid materials, including the single group coordination reaction mechanism (SGCRM), double group chelation reaction mechanism (DGCRM) and bridge coordination reaction mechanism (BCRM) are discussed in detail and confirmed by FT‐IR spectroscopy. The sizes of the TiO2/SiO2 hybrid material nanoparticles are also characterized and calculated by TEM and range from 20–40 nm. The diameter of the particles in the transparent spherical polymer matrix is ca. 100–200 nm and their shape is a regular spherical structure from TEM observations. The transparent spherical polymer matrix containing TiO2/SiO2 hybrid materials could be used as holographic anti‐counterfeiting materials. 相似文献
11.
A highly sunlight active Ni-loaded TiO2 nanocomposite (Ni/TiO2) is successfully prepared by a simple chemical reduction method using tetrabutyl titanate as a precursor, Ni(NO3)2·6H2O as a nickel source, and N2H4·H2O as a reductant, respectively. The crystal structure, morphology and UV–vis diffuse reflectance characteristics are investigated by XRD, TEM, and UV–vis diffuse reflectance spectroscopy, while the photocatalytic performance of Ni/TiO2 is evaluated by photocatalytic degradation of methyl orange solution under UV and sunlight irradiation. Results show that the crystal structure of TiO2 is not changed upon the loading of Ni, the photocatalytic performance of TiO2 under both UV-light and sunlight, however, is enhanced greatly. The enhancement of the photocatalytic performance of Ni/TiO2 is attributed to the increase of the photogenerated electron–hole separation efficiency and the advanced absorption of light due to surface plasmon effect of Ni nanoparticles. 相似文献
12.
为了更有效地利用太阳能,以钛酸丁酯为前驱体,硝酸镧和四丁基氢氧化铵为掺杂离子给体,通过改进的溶胶-凝胶法,成功制备了纯TiO2和不同掺杂浓度的镧、碳掺杂和共掺杂TiO2光催化剂.表征结果显示,共掺杂催化剂为锐钛矿型,具有较高的比表面积,感光范围拓展到可见光区.分别以甲基橙、罗丹明B和4-氯酚为降解物,氙灯、太阳光和自然光为光源,进行催化剂的光催化降解实验,结果表明,共掺杂催化剂活性高于未掺杂和单掺杂催化剂.降解结果显示,当共掺杂催化剂含0.5% La3+(摩尔比)、焙烧温度在500℃时具有最高的光催化降解效率.共掺杂TiO2具备较高的可见光催化活性原因可能是碳掺杂降低了TiO2禁带宽度,而镧掺杂同时维持了体系的电荷平衡. 相似文献
13.
《Reactive and Functional Polymers》2012,72(6):365-371
In this work, composite microspheres were prepared by casting a toluene solution of tetrabutyl titanate and poly(styrene-block-butadiene) copolymer in a methanol vapor atmosphere. It has been observed that the cooling of the surface of the polymer solution from the evaporation of the solvent results in condensation of methanol vapor. The condensed methanol spreads out on the substrate because of its lower surface tension, while the polymer solution with higher surface tension would shrink to form the final microspheres. The distribution of Ti was analyzed to directly evidence the above mechanism for the formation of the microspheres. The Ti was found to enrich at the outer surface of the composite microsphere because of the hydrolysis and the consequent dehydratative polycondensation reactions of tetrabutyl titanate when the composite microspheres were placed in air. The obtained composite microspheres were then subjected to a water vapor phase hydrothermal post-treatment to produce strong Ti-oxo type networks, which would form the framework to maintain the original spherical shape. Then, the composite microspheres were calcined in air at 550 °C to remove the polymer; thus, hollow TiO2 microspheres have been fabricated. The obtained hollow TiO2 microspheres were applied to the degradation of methyl orange under UV irradiation and revealed a satisfactory photocatalytic activity. 相似文献
14.
Yuxi Yu Yadi Guo Xuan Cheng Ying Zhang 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(4):714-719
A synthesis of titanium-containing polycarbosilane (Ti-PCS) and transformation to SiO2/TiO2 hybrid ceramics are investigated. The Ti-PCS is prepared by blending polycarbosilane (PCS) and tetrabutyl titanate in xylene. The structural evolution and chemical composition change during the pyrolysis of the Ti-PCS are characterized by chemical analysis, TG-DTA, XRD, XPS and TEM. The results reveal that the polymer-to-ceramic transition of the Ti-PCS involves three steps. The final ceramics obtained at 1200 °C contain amorphous silica and rutile-TiO2 nanocrystallites of ~10 nm. 相似文献
15.
Ordered hexagonal mesoporous TiO2 thin film was prepared by the evaporation-induced self-assembly (EISA) method using triblock copolymer (Pluronic P123) and
tetrabutyl orthotitanate (Ti(OBu
n
)4, TBOT) in 1-methoxy-2-propanol (C4H10O2, PGME) solvent. The arrangement of mesopores was identified by small-angle X-ray diffraction and transmission electron microscopy
(TEM). The well-ordered hexagonal mesoporous TiO2 had a high specific surface area of 239 m2/g and an average pore size of 6.3 nm. The structure of mesoporous TiO2 thin film was anatase with a 5.1 nm crystallite. The absorption band shift of the mesoporous TiO2 toward longer wavelengths as calcined at 350 °C due to the residual carbon. 相似文献
16.
《Ceramics International》2016,42(3):3808-3815
SnS2/TiO2 nanocomposites have been synthesized via microwave assisted hydrothermal treatment of tetrabutyl titanate in the presence of SnS2 nanoplates in the solvent of ethanol at 160 °C for 1 h. The physical and chemical properties of SnS2/TiO2 were studied by XRD, FESEM, EDS, TEM, XPS and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activity of SnS2/TiO2 nanocomposites were evaluated by photoreduction of aqueous Cr(VI) under visible light (λ>420 nm) irradiation. The experimental results showed that the SnS2/TiO2 nanocomposites exhibited excellent reduction efficiency of Cr(VI) (~87%) than that of pure TiO2 and SnS2. The SnS2/TiO2 nanocomposites were expected to be a promising candidate as effective photocatalysts in the treatment of Cr(VI) wastewater. 相似文献
17.
Al-doped TiO<Subscript>2</Subscript> mesoporous materials: synthesis and photodegradation properties
Aluminium-doped TiO2 mesoporous material was successfully fabricated by solid-state reaction with cetyltrimethylammonium bromide as a template
agent and tetrabutyl orthotitanate as a precursor. The characteristic results from low-angle and wide-angle X-ray diffraction,
high resolution transmission electron microscopy and energy dispersive spectroscopy, N2 absorption–desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet visible light spectroscopy
and X-ray photoelectron spectroscopy (XPS) clearly showed that the mesoporous architecture of aluminium-doped TiO2 was composed of crystal wall and micro-/mesopore formed gradually by the mesopore degradation of anatase TiO2, and aluminium had been doped into the framework of anatase TiO2. The mesoporous Al-doped TiO2 material, not only possessed high thermal stability hexahedral mesostructure, large BET surface area and narrow distribution
of pore size, but also showed excellent photodegradation behavior for Congo Red. Furthermore the medium UV–Vis absorption
peak of mesoporous aluminium-doped TiO2 in the range 210–370 nm was the absorption peak of aluminium oxide nanoparticles locating the extraframework of TiO2. A small quantity of aluminium doped into anatase TiO2 could obviously improve photodegradation activity, and the photodegradation activity of aluminium-doped TiO2 was higher than that of pure TiO2. 相似文献
18.
Huabing Jiang Guoliang Zhang Tao Huang Jinyuan Chen Qidong Wang Qin Meng 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2010,156(3):571-577
Nano-titanium dioxide (TiO2) photocatalyst was prepared by acid–sol method using tetrabutyl titanate and ethanol, which appeared to be anatase by XRD analysis. The wastewater containing azo dye acid red B was then subjected to photocatalytic degradation with photocatalyst TiO2 and UV as light source in a slurry photocatalytic membrane reactor, which included a double layer cylindrical photocatalytic reaction zone and a plate frame membrane separation part. Two kinds of ultrafiltration (UF) membranes PVDF700 and PAN700 were applied and the combined process with photocatalysis was operated by a continuous re-circulating mode during treatment. At first, the adsorption characteristic of the titanium dioxide catalyst under different pH values was analyzed and the optimal operation condition of the photocatalytic process was achieved by changing TiO2 dose and initial concentration of the dye. Then the performance of photocatalyst separation process by ultrafiltration (UF) was investigated. It was found that the degradation of acid red B was followed by first-order kinetics and the efficiency of photocatalysis can be evaluated by the initial reaction rate. Finally, the conglomeration and hydrophilizion phenomena by TiO2 in the coupling system and its effect to different ultrafiltration membranes were analyzed. 相似文献
19.
Jaturong Jitputti Thitima Rattanavoravipa Surawut Chuangchote Sorapong Pavasupree Yoshikazu Suzuki Susumu Yoshikawa 《Catalysis communications》2009,10(4):378-382
Monodispersed flower-like titanate superstructure was successfully prepared by simple hydrothermal process without any surfactant or template. N2-sorption analysis, scanning electron microscopy (SEM), and X-ray diffraction (XRD) observation of as-synthesized product revealed the formation of flower-like titanate with diameter of about 250–450 nm and BET surface area (SBET) of 350.7 m2 g?1. Upon thermal treatment at 500 °C, the titanate nanosheets were converted into anatase TiO2 with moderate deformation of their structures. The as-prepared flower-like titanate showed high photocatalytic activity for H2 evolution from water splitting reaction. Moreover, the sample heat treated at 500 °C exhibited higher photocatalytic activity than that of commercial TiO2 anatase powder (ST-01). 相似文献
20.
Facile fabrication of ordered assembled TiO2/g-C3N4 nanosheets with enhanced photocatalytic activity
Minggao Song Mingchun Li Yintong Guo Xiyao Huang Sijin Wang Long Ren Laishi Li Yusheng Wu 《Ceramics International》2021,47(11):15594-15603
A series of assembled porous TiO2/g-C3N4 (TC) powders composed of spherical nanoparticles were synthesized by controlling the molar ratio of urea to tetrabutyl titanate (TBOT) in a facile hydrothermal process. A nanosheets-constructed hierarchical structure was obtained at the molar ratio of urea to TBOT of 10:1, which possessed uniform mesopores with bimodal distribution (0.5–1.5 nm and 2–20 nm) and interconnected macropores between TC nanosheets. The specific surface area achieved 98.4 m2 g?1. X-ray diffraction (XRD) patterns and high resolution transmission electron microscope (HRTEM) analysis proved that the nanosheets are made of overlapping TC nanocomposite. Photoluminescence (PL) spectra results illustrated that a well-defined hierarchical porous structure is particularly desired for the low recombination rate of carriers. Further, the TC-decorated carbon fiber (CF) cloth was obtained based on the nanosheets assembled hierarchical structure, which showed more outstanding photocatalytic behavior with high degradation capability for Rhodamine B (RhB) (99.9%) and tetracycline hydrochloride (89.8%) at 60 min by 500 W Xe lamp irradiation. After five consecutive cycles, the degradation efficiencies of TC/CF cloth for both RhB and tetracycline hydrochloride all remained above 90% of the initial value. 相似文献