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1.
Mesoporous anatase TiO 2 nanopowder was synthesized by hydrothermal method at 130 °C for 12 h. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), HRTEM, and Brunauer-Emmett-Teller (BET) surface area. The as-synthesized sample with narrow pore size distribution had average pore diameter about 3-4 nm. The specific BET surface area of the as-synthesized sample was about 193 m 2/g. Mesoporous anatase TiO 2 nanopowders (prepared by this study) showed higher photocatalytic activity than the nanorods TiO 2, nanofibers TiO 2 mesoporous TiO 2, and commercial TiO 2 nanoparticles (P-25, JRC-01, and JRC-03). The solar energy conversion efficiency ( η) of the cell using the mesoporous anatase TiO 2 was about 6.30% with the short-circuit current density (Jsc) of 13.28 mA/cm 2, the open-circuit voltage (Voc) of 0.702 V and the fill factor (ff) of 0.676; while η of the cell using P-25 reached 5.82% with Jsc of 12.74 mA/cm 2, Voc of 0.704 V and ff of 0.649. 相似文献
2.
A new photocatalyst titania:activated carbon (TiO 2:AC) composite was prepared by impregnating anatase type TiO 2 nanoparticulates onto the activated carbon surface through a mild hydrothermal route. A varied ratio of TiO 2 to AC was considered for impregnation. As-prepared TiO 2:AC composite was characterized by various techniques such as powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), BET surface area and positron annihilation lifetime spectroscopy (PALS). Powder XRD results showed the persisting nature of anatase phase of TiO 2 deposited on the activated carbon surface. The BET, FTIR and PALS results revealed the impregnation threshold. The TiO 2 particulates were well adhered and uniformly dispersed on the carbon surface as confirmed by SEM. 相似文献
3.
Pure anatase mesoporous TiO 2 nanospheres were synthesized by simple wet chemical treatment and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD). The results revealed that the surface morphology of the TiO 2 spheres could be controlled by adjusting the concentration of N-methylaniline and that the average diameter of the TiO 2 spheres was 600 nm. FTIR results confirmed the formation of N-methylaniline capped TiO 2 nanospheres. 相似文献
4.
Highly-active anatase TiO 2 nanorods have been successfully synthesized via a simple two-step method, hydrothermal treatment of anatase/rutile titanium dioxide nanoparticle powder in a composite-hydroxide eutectic system of 1:1 M KOH/NaOH, followed by acid post-treatment. The morphology and crystalline structure of the obtained nanorods were characterized using XRD, TEM, SEM/EDX and BET surface area analyzer. The obtained TiO 2 nanorods have a good crystallinity and a size distribution (about 4-16 nm); with the dimensions of 200-300 nm length and of 30-50 nm diameter. Compared with its precursor anatase/rutile TiO 2 nanoparticles and the titanate nanotubes, the pure anatase TiO 2 nanorods have a large specific surface area with a mesoporous structure. The photocatalytic performance of the prepared nanorods was tested in the degradation of the commercial Cibacrown Red (FN-R) textile dye, under UV irradiation. Single-crystalline anatase TiO 2 nanorods are more efficient for the dye removal. 相似文献
5.
Pure TiO2 and Cu–doped TiO2 containing different amounts of copper ions with anatase/rutile/brookite triphasic structure were successfully synthesized through a simple hydrothermal method. The obtained samples were characterized by X–ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), X–ray photoelectron spectroscopy (XPS), UV?vis diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL) and Brunauer–Emmett–Teller surface area analyze (BET). Both pure and Cu–doped TiO2 show relatively high photocatalytic activity owing to their considerable surface areas. Moreover, the three–phase coexisting structure and the conversion between Cu2+ and Cu+ ions facilitate the separation of photogenerated electrons and holes, which is favorable for photocatalytic performance. 1%Cu–TiO2 exhibits the highest photocatalytic activity and the degradation degree of rhodamine B (RhB) reaches 93.5% after 30 min, which is higher than that of monophasic/biphasic 1%Cu–TiO2. ·O2? radical is the main active species, and h+ and ·OH species are subsidiary in the degradation process. 相似文献
6.
Large-scale fan-shaped rutile TiO 2 nanostructures have been synthesized by means of a simple hydrothermal method using only TiCl 4 as titanium source and chloroform/water as solvents. The physicochemical features of the fan-shaped TiO 2 nanostructures are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), nitrogen absorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) and Fourier transform infrared spectroscopy (FTIR). Structural characterization indicates that the fan-shaped TiO 2 nanostructures are composed of several TiO 2 nanorods with diameters of about 5 nm and lengths of 300-350 nm. The average pore size and BET surface area of the fan-shaped TiO 2 nanostructures are 6.2 nm and 59 m 2/g, respectively. Optical adsorption investigation shows that the fan-shaped TiO 2 nanostructures possess optical band gap energy of 3.11 eV. 相似文献
7.
Well-aligned anatase and rutile TiO 2 nanorods and nanotubes with a diameter of about 80–130 nm have successfully been fabricated via sol-gel template method.
The prepared samples were characterized by using thermogravimetric (TG) and differential thermal analysis (DTA), X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy
(EDS). The XRD results indicated that the TiO 2 nanorods were crystallized in the anatase and rutile phases, after annealing at 400–800 °C for different periods of time
from 0.2 to 10 h. 相似文献
8.
In this paper, TiO 2 hollow nanostructures with anatase walls have been rapidly fabricated by using CuO as template and microwave heating. These TiO 2 hollow nanostructures have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Experimental results showed that the TiO 2 shell transformed from amorphous to anatase phase in 3 min, induced by the hot CuO core under microwave irradiation. The diameter of TiO 2 hollow nanostructures is about 50-80 nm, and the length is about 200-300 nm. The thickness of the shell is about 3 nm. This method is promising to be used to synthesize other nanomaterials with a hollow nanostructure. 相似文献
9.
Pure anatase TiO 2 nanoparticles were synthesized by microwave assisted sol–gel method and further characterized by powder X-ray diffraction
(XRD), energy dispersive x-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM),
and UV–Visible spectrophotometer, SEM images showed that TiO 2 nanoparticles were porous structure. The XRD patterns indicated that TiO 2 after annealed at 300 °C for 3 h was mainly pure anatase phase. The crystallite size was in the range of 20–25 nm, which
is consistent with the results obtained from TEM images. Microwave heating offers several potential advantages over conventional
heating for inducing or enhancing chemical reactions. 相似文献
10.
Undoped and Ag-doped TiO 2 anatase nanocrystals were successfully prepared from titanium isopropoxide by a novel fast-hydrothermal method. The as-prepared TiO 2 nanocrystals were characterized by XRD, DRUV-VIS spectroscopy and SEM/EDX. The results show that the anatase TiO 2 has a particle size of around 4 nm from SEM and XRD results. 相似文献
11.
Using zinc naphthenate and titanium tetra isopropoxide (1:1 mol.%) dissolved in ethanol as precursors, single phase Zn 2TiO 4 nanoparticles were synthesized by the flame spray pyrolysis technique. The Zn 2TiO 4 nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The BET surface area ( SSABET) of the nanoparticles was measured by nitrogen adsorption. The average diameter of Zn 2TiO 4 spherical particles was in the range of 5 to 10 nm under 5/5 (precursor/oxygen) flame conditions. All peaks can be confirmed to correspond to the cubic structure of Zn 2TiO 4 (JCPDS No. 25-1164). The SEM result showed the presence of agglomerated nanospheres with an average diameter of 10-20 nm. The crystallite sizes of spherical particles were found to be in the range of 5-18 nm from the TEM image. An average BET equivalent particle diameter ( dBET) was calculated using the density of Zn 2TiO 4. 相似文献
12.
The aim of this work is to examine the properties of CNTs formed on Fe-Co and Ni-Co bimetallic catalysts supported on different phases of TiO 2 (anatase and rutile) by wet impregnation method. The CNTs are grown from decomposition of acetylene via Thermal CVD at 700°C using the prepared catalysts. The nanomaterials were characterized by XRD, Xmap, BET, FESEM, TEM, and Raman spectroscopy. It was found that the catalyst samples supported on rutile TiO 2 have higher specific surface area, smaller catalytic nanoparticles with denser distribution and very more activity compared to anatase ones. Consequently, the CNTs nucleated from nanoparticles supported on rutile TiO 2 possess higher density, smaller average diameters and narrower diameter distribution compared to grown CNTs on anatase samples. Moreover, it was observed that the Fe-Co bimetallic catalysts regardless of TiO 2 support phase, possesses more catalytic activity and higher average growth rate of CNTs in compare with Ni-Co catalysts. 相似文献
13.
The nano-crystalline B 3+ and F ? co-doped titanium dioxide films were successfully prepared by the improved sol–gel process. The as-prepared specimens were characterised using X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (FE-SEM), the Brunauer–Emmett–Teller (BET) surface area, X-ray photo-electron spectroscopy, photoluminescence spectra and UV–Vis diffuse reflectance spectroscopy. The photo-catalytic activities of the films were evaluated by degradation of an organic dye in aqueous solution. The results of XRD, FE-SEM and BET analysis indicated that the TiO 2 films were composed of nano-particles. B 3+ and F ? co-doping could obviously not only suppress the formation of brookite phase but also inhibit the transformation of anatase to rutile at high temperature. Diffuse reflectance measurements showed that co-doping could clearly extend the absorbance spectra of TiO 2 into visible region. Compared with pure TiO 2, B 3+ doped or F ? doped TiO 2 film, the B 3+ and F ? co-doped TiO 2 film exhibited excellent photo-catalytic activity. It is believed that the surface microstructure of the films and the doping methods of the two ions are responsible for improving the photo-catalytic activity. 相似文献
14.
The nanocrystalline S doped titanium dioxide films were successfully prepared by the improved sol-gel process. Here TiO(C 4H 9O) 4 and CS(NH 2) 2 were used as precursors of titania and sulfur, respectively. The as-prepared specimens were characterized using x-ray diffraction (XRD), x-ray energy dispersive spectroscopy (EDS), high-resolution field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) surface area, and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic activities of the films were evaluated by degradation of organic dyes in aqueous solution. The results of XRD, FE-SEM, and BET analyses indicated that the TiO 2 films were composed of nanoparticles. S doping could obviously not only suppress the formation of brookite phase but also inhibit the transformation of anatase to rutile at high temperature. Compared with pure TiO 2 film, S doped TiO 2 film exhibited excellent photocatalytic activity. It is believed that the surface microstructure of the modified films is responsible for improving the photocatalytic activity. 相似文献
15.
Interest in the photocatalytic oxidation of formaldehyde from contaminated wastewater is growing rapidly. The photocatalytic activity of the nanocrystalline Fe 3+/F ? co-doped TiO 2–SiO 2 composite film for the degradation of formaldehyde solution under visible light was discussed in this study. The films were characterised by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy, X-ray diffraction (XRD), BET surface area, UV–Vis absorption spectroscopy, and photoluminescence spectroscopy. The FE-SEM results revealed that the Fe 3+/F ? co-doped TiO 2–SiO 2 film was composed of uniform round-like nanoparticles or aggregates with the size range of 5–10 nm. The XRD results indicated that only the anatase phase was observed in the film. Compared with a pure TiO 2 film and a singly modified TiO 2 film, the Fe 3+/F ? co-doped TiO 2–SiO 2 composite film showed the best photocatalytic properties due to its strong visible light adsorption and diminished electrons-holes recombination. 相似文献
16.
The nano-scale ZnO/TiO 2 coupled oxide photocatalyst was successfully synthesized by a two-step method, the homogeneous hydrolysis and low temperature crystallization. The resultant photocatalyst was characterized by ultraviolet-visible absorption spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) techniques. The photocatalytic activity of coupled oxides was also evaluated by the degradation of methyl orange (MO) as a model compound. The experimental results showed that the prepared ZnO/TiO 2 at low hydrothermal crystallization temperature exhibited higher photocatalytic activity for the decomposition of MO than either pure phase ZnO or anatase TiO 2, and even higher than that of the Degussa P25 TiO 2. 相似文献
17.
Three approaches, impregnation–reduction, deposition and direct assembly, are used to fabricate gold-modified TiO 2 nanotubes. Prepared materials are characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV–visible absorption spectroscopy and BET, etc. The gold-modified TiO 2 nanotubes prepared via various procedures exhibit distinct difference in structure. By impregnation–reduction approach, gold-modified TiO 2 nanotubes with large gold particles are fabricated. The gold particles are either deposited on or encapsulated in TiO 2 nanotubes. However, by using gold hydrophilic colloidal dispersion as gold precursor, gold particles in the modified TiO 2 nanotubes are very small. Gold particles only adhere to the outer surface of TiO 2 nanotubes after deposition process, whereas adhere to not only the outer but also the inner walls of TiO 2 nanotubes after direct assembly process. A possible mechanism is proposed to illustrate the formation of gold-modified nanotubes that are prepared by direct assembly process. 相似文献
18.
Optimized synthesis of Ti-precursor ‘titanylnitrate’ for one step combustion synthesis of N- and C-doped TiO 2 catalysts were reported and characterized by using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), diffused reflectance UV–vis spectroscopy, N 2 adsorption and X-ray photoelectron spectroscopy (XPS). XRD confirmed the formation of TiO 2 anatase and nano-crystallite size which was further confirmed by TEM. UV-DRS confirmed the decrease in the band gap to less than 3.0 eV, which was assigned due to the presence of C and N in the framework of TiO 2 as confirmed by X-ray photoelectron spectroscopy. Degradation of methylene blue in aqueous solution under the direct sunlight was carried out and typical results indicated the better performance of the synthesized catalysts than Degussa P-25. 相似文献
19.
Using triethylamine as a surface protective agent, a transparent and pale yellowish TiO 2 sol had been prepared at 90 °C. This method was very different from the traditional methods, which produced titanium dioxide nanoparticles with anatase crystalline structure either at high acid condition or high temperature. X-ray diffraction (XRD) and transmission electron spectroscopy (TEM) demonstrated that the as-prepared TiO 2 sol nanoparticles with anatase crystalline structure were uniformly distributed, and the average size was 3 nm. X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectra showed that triethylamine was adsorbed on TiO 2 sol particles surface. FTIR spectroscopy noted that TiO 2 sol particles had the similar spectra with Degussa P25. Photoactivity of the as-prepared TiO 2 sol was studied by investigating the photodegradation of methyl violet in hydrosol reaction system under visible light irradiation. 相似文献
20.
A liquid fuel high velocity oxy-fuel (HVOF) thermal spray process has been used to deposit TiO 2 nanostructured coatings utilizing a commercially available nanopowder as the feedstock. The coatings were characterized by
means of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM),
respectively. Photocatalytic activity was evaluated as a rate constant of decomposition reaction of methylene blue (MB) determined
from the changes of relative concentration of MB with UV irradiation time. The results indicate that the sprayed TiO 2 coatings were composed of both TiO 2 phases viz. anatase and rutile, with different phase contents and crystallite sizes. A high anatase content of 80% by volume
was achieved at 0·00015, fuel-to-oxygen ratio with nanostructure coating by grain size smaller than feedstock powder. Photocatalytic
activity evaluation results indicated that all the TiO 2 coatings are effective to degradation MB under UV radiation and their activities differ in different spray conditions. It
is found that fuel flow rate strongly influenced on phase transformation of anatase to rutile and by optimizing the rate which
can promote structural transformation and grain coarsening in coating and improving photocatalytic activity. 相似文献
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