共查询到20条相似文献,搜索用时 31 毫秒
1.
Melinda VargováGustav Plesch Ulrich F. Vogt Miroslav ZahoranMichal Gorbár Karol Jesenák 《Applied Surface Science》2011,257(10):4678-4684
TiO2 thick films deposited on macroporous reticulated Al2O3 foams with pore size of 10 ppi and 15 ppi were prepared using dip coating from slurries of Aeroxide® P25 nanopowder and precipitated titania. All prepared films have sufficiently good adhesion to the surface of the substrate also in case of strongly cracked films. No measurable release of deposited TiO2 after repeated photocatalytic cycles was observed. The photocatalytic activity was characterized as the rate of mineralization of aqueous phenol solution under irradiation of UVA light by TOC technique. The best activity was obtained with Aeroxide® P25 coated Al2O3 foam with the pore size of 10 ppi, annealed at 600 °C. The optimal annealing temperature for preparation of films from precipitated titania could be determined at 700 °C. Films prepared by sol-gel deposition technique were considerably thinner compared to coatings made of suspensions and their photocatalytic activity was significantly smaller. 相似文献
2.
Zr-containing mesoporous molecular sieves were synthesized by hydrothermal method using cetyltrimethyl ammonium bromide as a template and sodium silicate and zirconium sulfate as raw materials. The structure and morphology of the synthesized samples were characterized via various physicochemical methods, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, solid state nuclear magnetic resonance (29Si MAS-NMR) techniques, thermal gravimetric-differential scanning calorimeter (TG-DSC) and N2 physical adsorption, respectively. The effect of the different initial ZrO2:SiO2 molar ratio, the different thermal treatment temperature and the different hydrothermal treatment time on textural property was investigated. The experimental results reveal that the as synthesized samples possess a typical mesoporous structure of MCM-41. On the other hand, the specific surface area and pore volume of the synthesized Zr-MCM-41 mesoporous molecular sieve decrease with the increase of the amount of zirconium incorporated in the starting material, the rise of thermal treatment temperature and the prolonging of hydrothermal treatment time, the mesoporous ordering becomes poor. Also, when the molar ratio of ZrO2:SiO2 in the starting material is 0.1, the mesoporous structure of the Zr-MCM-41 mesoporous molecular sieve still retains after calcination at 750 °C for 3 h or hydrothermal treatment at 100 °C for 6 d, and have specific surface areas of 423.9 and 563.9 m2/g, respectively. 相似文献
3.
Titania hollow submicrospheres with mixed phase (anatase-brookite or anatase-rutile) were synthesized via the combination of hydrothermal treatment and calcination of submicrospheres consisting of a polystyrene core and an amorphous TiO2 shell. After hydrothermal treatment, amorphous titania shell could be transformed to anatase-brookite shell consisting of loose packed titania nanocrystals, which could be further converted to anatase-brookite (below 700 °C) or anatase-rutile titania (700-800 °C) hollow spheres with rough surface via calcination. The loose packing of titania nanocrystals not only inhibited the transformation temperature from anatase to rutile, but also provided titania hollow submicrospheres with high photodegradation activity of Rhodamine B. The photocatalytic activity of titania hollow spheres increased firstly then decreased when the calcination temperature was varied in the range of 450-800 °C, while hollow spheres obtained via calcinating at 700 °C exhibited the highest photocatalytic activity, which was five times higher than that of counterpart without hydrothermal treatment. 相似文献
4.
Zhi-Jian Chen Yi-Lin Chen Ke-Zhi Zhang Bin Li Hai Zhu 《Journal of Physics and Chemistry of Solids》2010,71(5):841-368
Mesoporous α-Fe2O3-pillared titanate nanocomposites have been successfully synthesized through an exfoliation−restacking route. Powder X-ray diffraction and N2 adsorption-desorption isotherms revealed that the α-Fe2O3 pillared titanate has an interlayer distance of 3.27 nm, a specific surface area of 66 m2/g and an average pore size of 7.6 nm, suggesting the formation of a mesoporous pillared structure. UV-vis diffuse reflectance spectra show a red shift, indicative of a narrow band gap energy of ∼2.1 eV compared to the host layered titanate, which is essential in creating a visible light photocatalytic activity. The results of degradation of rhodamine B reveal that the present pillared mesoporous composites exhibit better photocatalytic activities than those of the pristine materials under visible irradiation, based on the band gap excitement and the dye-sensitized path, originated from their high surface area, mesoporosity and the electronic coupling between the host and the guest components. 相似文献
5.
Haijiao Su Liqiang Jing Keying Shi Changhao Yao Honggang Fu 《Journal of nanoparticle research》2010,12(3):967-974
Nanosized LaFeO3 with large specific surface area has been successfully synthesized by an impregnation process, with mesoporous silica SBA-16
as hard template and corresponding metal nitrates as La and Fe resources, and the resulting LaFeO3 is also characterized by thermogravimetry–differential thermal analysis (TG–DTA), X-ray diffraction (XRD), N2 adsorption–desorptions, Brunauer Emmett Teller (BET) technique, transmission electron microscopy (TEM), X-ray photoelectron
spectroscopy (XPS), UV–visible diffuse reflection spectrum (UV–Vis DRS), and surface photovoltage spectroscopy (SPS). It is
found that, compared with that prepared by the conventional citrate method, the as-prepared LaFeO3 with 20-50 nm particle size has remarkable large specific surface area, even still with the surface area as large as about
85 m2 g−1 after calcination at 800 °C, which is attributed to its mesoporous structure as well as the small particle size. During the
photocatalytic degradation of Rhodamine B solution under visible irradiation, all the LaFeO3 samples obtained are superior to P25 TiO2, and the activity becomes high with increasing calcination temperature. It is revealed that the excellent photocatalytic
performance is mainly ascribed to the large surface area and high photogenerated charge separation rate. 相似文献
6.
Hiroyuki Takano Koichi IzumiyaNaokazu Kumagai Koji Hashimoto 《Applied Surface Science》2011,257(19):8171-8176
The active catalysts for methane formation from the gas mixture of CO2 + 4H2 with almost 100% methane selectivity were prepared by reduction of the oxide mixture of NiO and ZrO2 prepared by calcination of aqueous ZrO2 sol with Sm(NO3)3 and Ni(NO3)2. The 50 at%Ni-50 at%(Zr-Sm oxide) catalyst consisting of 50 at%Ni-50 at%(Zr + Sm) with Zr/Sm = 5 calcined at 650 or 800 °C showed the highest activity for methanation. The active catalysts were Ni supported on tetragonal ZrO2, and the activity for methanation increased by an increase in inclusion of Sm3+ ions substituting Zr4+ ions in the tetragonal ZrO2 lattice as a result of an increase in calcination temperature. However, the increase in calcination temperature decreased BET surface area, metal dispersion and hydrogen uptake due to grain growth. Thus, the optimum calcination temperature existed. 相似文献
7.
R.M. Grudzien 《Applied Surface Science》2007,253(13):5660-5665
Cage-like ordered mesoporous silicas, SBA-16, and ethane-silicas with cubic (Im3m) and (Fm3m) symmetry groups were synthesized with addition of sodium chloride by using tetraethyl orthosilicate (TEOS) as silica precursor, 1,2-bis(triethoxysilyl)ethane (BTESE) as bridged silsesquioxane and poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymer Pluronic F127 (EO106PO70EO106) as template at low acid concentrations. The resulting samples were subjected to extraction in order to remove the polymeric template. The as-synthesized and extracted materials were calcined in the range of 350-900 °C to determine their thermal stability. Based on the XRD analysis and nitrogen adsorption data such as the BET specific surface area, volume of primary mesopores, pore wall thickness and pore size distributions, the SBA-16 silicas exhibit relatively high thermal stability because their mesostructural ordering was retained even up to 900 °C. However, an increase in the calcination temperature tended to decrease significantly the BET surface area, volumes of primary and complementary pores, and to less extent the pore size and pore wall thickness due to the structural shrinkage. Furthermore, the as synthesized samples subjected to a short extraction with acidic ethanol solution possessed even better thermal stability. On the other hand, calcination at 550 °C of ethane-silicas caused a complete removal of the ethane bridging groups from the periodic mesoporous organosilicas and their calcination above 800 °C led to the partial collapse of the structure. 相似文献
8.
Visible-light-activated Ce-Si co-doped TiO2 photocatalyst 总被引:1,自引:0,他引:1
To enhance the visible photocatalytic activity and thermal stability of TiO2, Ce-Si co-doped TiO2 materials were synthesized through a nonaqueous method of which the purpose was to reduce the aggregation between TiO2 particles. The obtained materials maintained anatase phase and large surface area of 103.3 m2 g−1 even after calcined at 800 °C. The XPS results also indicated that Si was weaved into the lattice of TiO2, and Ce mainly existed as oxides on the surface of TiO2 particles. The doped Si might enhance surface area and suppress transformation from anatase to rutile, while the doped Ce might cause visible absorption and inhibit crystallite growth during heat treatment. Evaluated by decomposing dye Rhodamine B, visible photocatalytic activity of Ce-Si co-doped TiO2 was obviously higher than that of pure TiO2 and reached the maximum at Ce and Si contents of 0.5 mol% and 10 mol%. 相似文献
9.
Mirta N. Blanco 《Applied Surface Science》2010,256(11):3546-78
The tungstosilicic acid/titania composites were prepared by the sol-gel method. Titanium isopropoxide was used as titania precursor, and urea as a low-cost template. The tungstosilicic acid (TSA) was added in the same step as that in which titania hydrogel is formed. The TSA-modified samples only showed the characteristic peaks of anatase phase of titanium oxide in the XRD patterns, indicating that the presence of TSA retarded the crystallization of the anatase phase and its transformation into the rutile phase. Spherical particles with sizes between 200 and 700 nm, formed by aggregation of nanoparticle aggregates (4-50 nm in size), were observed. The particle size increased when the TSA content was raised and also increased slightly with the thermal treatment temperature. Mesoporous materials were obtained, with a mean pore diameter higher than 3.1 nm. Both the increase of the TSA concentration in the solid and the calcination temperature led to a decrease in the specific surface area of the samples. The main heteropolyoxometallate species present in the composites is the [SiW12O40]4− anion for the composites calcined up to 500 °C. The band gap energy decreased as a result of the introduction of TSA into the titania matrix, though it remained almost constant with the calcination temperature increase. 相似文献
10.
Preparation and characterization of activated carbon produced from pomegranate seeds by ZnCl2 activation 总被引:1,自引:0,他引:1
In this study, pomegranate seeds, a by-product of fruit juice industry, were used as precursor for the preparation of activated carbon by chemical activation with ZnCl2. The influence of process variables such as the carbonization temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons was studied. When using the 2.0 impregnation ratio at the carbonization temperature of 600 °C, the specific surface area of the resultant carbon is as high as 978.8 m2 g−1. The results showed that the surface area and total pore volume of the activated carbons at the lowest impregnation ratio and the carbonization temperature were achieved as high as 709.4 m2 g−1 and 0.329 cm3 g−1. The surface area was strongly influenced by the impregnation ratio of activation reagent and the subsequent carbonization temperature. 相似文献
11.
Changyuan Hu Shuwang Duo Tingzhi Liu Junhuai Xiang Mingsheng Li 《Applied Surface Science》2011,257(8):3697-3701
Anatase TiO2 was prepared by a facile sol-gel method at low temperature through tailoring the pH of sol-gel without calcination. As a control, anatase TiO2 was also synthesized by the conventional sol-gel process, in which calcination at 500 °C was required to transform the amorphous oxide into highly crystalline anatase. As-prepared samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). Their photocatalytic activities were evaluated by degradation of methyl orange under UV light irradiation. On the basis of experiment results, it could be concluded that TiO2 prepared by low temperature route showed more advantages in small particle size, highly dispersion nature, abundance of surface hydroxyl groups, strong PL signal, and high photocatalytic activity over TiO2 obtained by the conventional sol-gel process. Furthermore, the reason of the former possessing higher photocatalytic activity was discussed. 相似文献
12.
Hui Huang Zhaoyang YuWenjun Zhu Yongping GanYang Xia Xinyong TaoWenkui Zhang 《Journal of Physics and Chemistry of Solids》2014
In this work, hierarchically porous TiO2–B nanoflowers have been successfully synthesized via a facile solvothermal method followed by calcination treatment. The TiO2–B nanoflowers are constructed by thin nanosheets, presenting ultrahigh specific surface area, up to 214.6 m2 g−1. As anode materials for Li-ion batteries, the TiO2–B sample shows high reversible capacity, excellent cycling performance and superior rate capability. The specific capacity of TiO2–B could remain over 285 mA h g−1 at 1 C and 181 mA h g−1 at 10 C rate after 100 cycles. We believe that the pseudocapacitive mechanism, ultrahigh surface area and scrupulous nanoarchitecture of the TiO2–B are responsible for the enhancement of electrochemical properties. 相似文献
13.
Low temperature synthesis of iodine-doped TiO2 nanocrystallites with enhanced visible-induced photocatalytic activity 总被引:1,自引:0,他引:1
Iodine-doped TiO2 nanocrystallites (denoted as I-TNCs) were prepared via a newly developed triblock copolymer-mediated sol-gel method at a temperature of 393 K. I-doping, crystallization and the formation of porous structure have been simultaneously achieved. The obtained particles were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-vis spectrophotometer. The results indicated that the as-prepared I-TNCs possessed a diameter of ca. 5 nm with anatase crystalline structure and a specific surface area of over 200 m2 g−1. The presence of iodine expanded the photoresponse in visible light range, and led to enrich in surface hydroxyl group on the TiO2 surface. Compared with the commercial photocatalyst P25, the I-TNCs significantly enhanced the photocatalytic efficiency in the degradation of rhodamine B and 2,4-dichlorophenol, and the I-TNCs with 2.5 mol% doping ratio exhibited the best photocatalytic activity. 相似文献
14.
The anatase-TiO2 transparent films, containing 3 mol% of Si and P elements (as dopants), were synthesized using a process combining the sol-gel method and spin-coating technique. Effects of relative ratio of dopants and calcination temperature on phase transformation, grain growth, surface morphology, light transmittance, band-gap energy and photocatalytic activity of the P/Si-TiO2 films were examined and their results were compared with those of the undoped-TiO2 and Si-TiO2 films. The P/Si-TiO2 films calcined at temperature between 600 and 900 °C adhered strongly to the surface of fused-silica substrate and were composed of anatase-TiO2 monophase. The photocatalytic activities of the films were measured and represented using a characteristic time constant (τ) for the methylene blue (MB) photodegradation. The small τ stands for high photocatalytic ability of the film. The P/Si-TiO2 film, containing equalmolar Si and P dopants, calcined at 800 °C gave the best performance in photocatalysis; this film had τ=5.7 h and decomposed about 90 mole% of MB in the water after 12 h of the 365-nm UV light irradiation. 相似文献
15.
High specific surface area TEOS-based aerogels with large pore volume prepared at an ambient pressure 总被引:3,自引:0,他引:3
The experimental results on the synthesis of tetraethoxysilane (TEOS)-based silica aerogel with high specific surface area and large pore volume, via ambient pressure drying (APD) route, are reported. The silica aerogels were prepared by the acid-base sol-gel polymerization of TEOS precursor followed by the drying of the alcogels at an ambient pressure. The solvent present in the alcogel (i.e. ethanol) was replaced by a non-polar solvent such as hexane prior to the surface modification step. In order to minimize the drying shrinkage, the surface of the gels was modified using trimethylchlorosilane (TMCS) before the APD. The FTIR spectra of the surface modified aerogels showed Si-CH3 peaks at 2965 and 850 cm−1. The effect of the base catalyst (NH4OH) addition to the sol, at different time intervals (T), on the physical and textural properties of the resulting aerogels has been investigated. It has been observed that the surface area and the cumulative pore volume of the aerogels enhanced considerably from 819 to 1108 m2 g−1 and 2.65 to 4.7 cm3 g−1, respectively with an increase in the T value from 6 to 48 h. Silica aerogels with very low bulk density (0.06 g cm−3), extremely high specific surface area (1108 m2 g−1) and large cumulative pore volume (4.7 cm3 g−1) could be synthesized by drying the alcogels at the ambient pressure. The aerogels were mesoporous solids with the average pore size ranging from 12 to 17 nm. The results have been discussed by taking into consideration the hydrolysis and condensation reactions during the sol-gel polymerization of the TEOS precursor. 相似文献
16.
Lin ZhuLixin Cao Ge SuWei Liu Liang SongHui Liu Bohua Dong 《Applied Surface Science》2011,257(18):7932-7937
Low-dimensional TiO2 nanoribbons were synthesized by a simple one-step hydrothermal method. The TiO2 nanoribbons were calcined over the temperature range 200-800 °C in order to enhance their photocatalytic properties by altering their crystal phase and increasing crystallization. Effects of hydrothermal temperature, calcinated temperature and calcination time on the formation of nanostructures have been observed and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The (BET) specific surface area of the samples which with different post treatments were determined by N2 absorption-desorption experiment. In addition, photocatalytic activities of the nanoribbons were evaluated by photodegradation of organic dyes methyl orange under the radiation of UV light. The results reveal that the post-treatments have great effects on the microstructures and the photocatalytic activities of TiO2 nanoribbons. 相似文献
17.
Silica-tin nanotubes prepared from rice husk ash by sol-gel method: Characterization and its photocatalytic activity 总被引:1,自引:0,他引:1
Farook Adam Jimmy Nelson Appaturi Radhika Thankappan Mohd Asri Mohd Nawi 《Applied Surface Science》2010,257(3):811-816
Silica-tin material has been synthesized by simple sol-gel method using rice husk ash as the source of silica and cetyltrimethylammonium bromide as the surfactant at room temperature. Calcination of the material at 500 °C for 5 h gave nanotubes with external diameter of 2-4 nm and an internal diameter of 1-2 nm. The BET specific surface area was found to be 607 m2 g−1. Nitrogen sorption analysis exhibits a type IV isotherm with H3 hysteresis loop. The powder X-ray diffraction pattern showed that the material is amorphous. The photocatalytic activity of the prepared material was studied towards degradation of methylene blue under UV-irradiation. According to the experimental results the silica-tin nanotubes exhibit high photocatalytic activity compared to pure rice husk silica. 相似文献
18.
Hongqiang Wang Jianhong Yang Qifa Dai 《Journal of Physics and Chemistry of Solids》2008,69(10):2420-2425
Three activated carbons (ACs) for the electrodes of supercapacitor were prepared from cationic starch using KOH, ZnCl2 and ZnCl2/CO2 activation. The BET surface area, pore volume and pore size distribution of the ACs were evaluated using density functional theory method, based on N2 adsorption isotherms at 77 K. The surface morphology was characterized with SEM. Their electrochemical performance in prototype capacitors was determined by galvanostatic charge/discharge characteristics and cyclic voltammetry, and compared with that of a commercial AC, which was especially prepared for use in supercapacitors. The KOH-activated starch AC presented higher BET surface area (3332 m2 g−1) and larger pore volume (1.585 cm3 g−1) than those of the others, and had a different surface morphology. When used for the electrodes of supercapacitors, it exhibited excellent capacitance characteristics in 30 wt% KOH aqueous electrolytes and showed a high specific capacitance of 238 F g−1 at 370 mA g−1, which was nearly twice that of the commercial AC. 相似文献
19.
Shuang Song Fangyue HongZhiqiao He Hongyu WangXianghong Xu Jianmeng Chen 《Applied Surface Science》2011,257(23):10101-10108
Zirconium and iodine co-doped titanium dioxide (Zr-I-TiO2) was prepared by the hydrolysis of tetrabutyl titanate, premixed with zirconium nitrate in an iodic acid aqueous solution, followed by calcination in air. The structure and properties of the resultant catalyst powders were characterized by X-ray diffraction, the Brunauer-Emmett-Teller method, X-ray photoelectron spectroscopy, transmission electron microscopy, and UV-vis absorption spectroscopy. The catalytic activity of the catalyst was evaluated by monitoring the photocatalytic decolorization of methyl orange under visible light irradiation. The results showed that the activities of Zr-I-TiO2 catalysts were higher than that of TiO2 doped with iodine alone (I-TiO2), and the optimal doping concentration in the Zr-I-TiO2 calcined at 400 °C was determined to be about 0.05 (molar ratio of Zr:Ti). In addition, the photocatalytic activity of Zr-I-TiO2 calcined at 400 °C was found to be significantly higher than that calcined at 500 or 600 °C. Based on the physico-chemical characterization, we concluded that the role of zirconium on the I-TiO2 surface is to increase the number of reactive sites by generating a small crystal size and large surface area. The inhibition of electron-hole pair recombination, by trapping photo-generated electrons with Zr4+, did not contribute markedly to the improved photocatalytic activity of Zr-I-TiO2. 相似文献
20.
Fe3+-doped TiO2 film deposited on fly ash cenosphere (Fe-TiO2/FAC) was successfully synthesized by the sol-gel method. These fresh photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). The XRD results showed that Fe element can maintain metastable anatase phase of TiO2, and effect of temperature showed rutile phase appears in 650 °C for 0.01% Fe-TiO2/FAC. The SEM analysis revealed the Fe-TiO2 films on the surface of a fly ash cenosphere with a thickness of 2 μm. The absorption threshold of Fe-TiO2/FACs shifted to a longer wavelength compared to the photocatalyst without Fe3+-doping in the UV-vis absorption spectra. The photocatalytic activity and kinetics of Fe-TiO2/FAC with varying the iron content and the calcination temperatures were investigated by measuring the photodegradation of methyl blue (MB) during visible light irradiation. Compared with TiO2/FAC and Fe3+-doped TiO2 powder (Fe-TiO2), the degradation ratio using Fe-TiO2/FAC increased by 33% and 30%, respectively, and the best calcined temperature was 450 °C and the optimum doping of Fe/Ti molar ratio was 0.01%. The Fe-TiO2/FAC particles can float in water due to the low density of FAC in favor of phase separation to recover these photocatalyst after the reaction, and the recovery test shows that calcination contributes to regaining photocatalytic activity of Fe-TiO2/FAC photocatalyst. 相似文献