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1.
In this paper, we report a kind of nano-TiO 2/stellerite composite with enhanced photoactivity, which was synthesized by a typical homogeneous precipitation method followed by a calcination crystallization process using natural stellerite as support. The as-prepared composites were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption, high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The results showed that TiO 2 loading amounts and calcination temperatures had significant influence on the adsorption and photocatalytic degradation properties of phenol. Moreover, it was indicated that the TiO 2 nanoparticles (NPs) with smaller grain size (around 12.0?nm) and narrower size distributions were uniformly deposited on the surface of stellerite as a layer of film. Compared with commercial P25, the received composite exhibited more superior photocatalytic degradation performance towards phenol. The enhanced photocatalytic degradation performance should result from the better dispersibility of TiO 2 NPs and higher separation efficiency of photogenerated electron-hole pairs. This work may set foundation for the practical application of this new composite photocatalyst in the field of wastewater treatment. 相似文献
2.
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
3.
A novel ternary heterojunction composite photocatalyst g-C3N4/TiO2/NiWO4 was fabricated using a simple hydrothermal method. The synthesized samples were characterized using X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy-dispersive spectrum (EDS), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) absorption spectra, photoluminescence (PL) spectra, transient photocurrent responses, and electrochemical impedance spectroscopies (EIS). The results indicated that the composite of g-C3N4/TiO2/NiWO4 had been successfully synthesized. By constructing a ternary heterojunction, the electron migration rate and light absorption of the material are further improved; the photogenerated electron–hole recombination is inhibited. The ternary composite photocatalyst shows the highest photocatalytic activity for the degradation of rhodamine B (RhB) than that of g-C3N4, TiO2, NiWO4, and g-C3N4/TiO2 photocatalyst. The degradation efficiency of RhB using g-C3N4/TiO2/NiWO4 can reach 99% after visible-light irradiation for 40 min. Finally, the migration mechanism of charge carriers in the ternary system has been schematically illustrated by the active species capture experiment. Our research can pave the way for the fabrication of ternary heterojunction composite photocatalyst with high photocatalytic activity for the environmental contaminants treatment. 相似文献
4.
One-dimensional hydrogen titanate ribbons were successfully prepared with hydrothermal reaction in a highly basic solution. A series of one-dimensional carbon-modified TiO 2 ribbons were prepared via calcination of the mixture of hydrogen titanate ribbons and sucrose solution under N 2 flow at different temperatures. The phase transformation process of hydrogen titanate ribbons was investigated by in-situ X-ray diffraction at various temperatures. Besides, one-dimensional carbon-modified TiO 2 ribbons calcined at different temperatures were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption isotherms, diffuse reflectance ultraviolet–visible spectroscopy, and so on. Carbon-modified TiO 2 ribbons showed one-dimensional ribbon crystal structure and various crystal phases of TiO 2. After being modified with carbon, a layer of uniform carbon film was coated on the surface of TiO 2 ribbons, which improved their adsorption capacity for methyl orange as a model organic pollutant. One-dimensional carbon-modified TiO 2 ribbons also exhibited enhanced visible-light absorbance with the increase of calcination temperatures. 相似文献
5.
TiO 2–SiO 2 composite nanotubes were successfully synthesized by a facile sol–gel technique utilizing ZnO nanowires as template. The nanotubes were well characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N 2 adsorption–desorption analysis and UV–vis diffuse reflectance spectroscopy. The nanotubular TiO 2–SiO 2 composite photocatalysts showed diameter of 300–325 nm, fine mesoporous structure and high specific surface area. The results indicated that the degradation efficiency of gaseous toluene could get 65% after 4 h reaction using the TiO 2–SiO 2 composite as the photocatalyst under UV light illumination, which was higher than that of P25. 相似文献
6.
Anatase TiO 2 thin films were successfully prepared on glass slide substrates via a sol–gel method from refluxed sol (RS) containing anatase TiO 2 crystals at low temperature of 100 °C. The influences of various refluxing time on crystallinity, morphology and size of the RS sol and dried TiO 2 films particles were discussed. These samples were characterized by infrared absorption spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission-scanning electron microscopy (FE-SEM) and UV–vis absorption spectroscopy (UV–vis). The photocatalytic activities of the TiO 2 thin films were assessed by the degradation of methyl orange in aqueous solution. The results indicated that titania films thus obtained were transparent and their maximal light transmittance exceeded 80% under visible light region. The TiO 2 thin films prepared from RS-6 sol showed the highest photocatalytic activity, when the calcination temperature is higher than 300 °C. The degradation of methyl orange of RS-6 thin films reached 99% after irradiated for 120 min, the results suggested that the TiO 2 thin films prepared from RS sol exhibited high photoactivities. 相似文献
7.
Nanoparticles of binary TiO 2–SiO 2 mixed oxides was prepared via sol–gel method using tetraethylorthosilicate (TEOS) and titanium isopropoxide (TIPP) in different reaction conditions (solvent and pH) using ammonium hyhdroxide, acetic acid, sodium hydroxide, ethyleneglycol and polyethylene glycol followed by calcination at 850–970 °C. The morphologies, structures and chemical compositions were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transmission infrared spectroscopy (FTIR) techniques. The catalytic activity of the obtained nanomaterials was explored for the dehydrogenation of 1,4-dihydropyridines (1,4-DHPs). Observation of 86–100% conversion and 100% selectivity towards the formation of desired products with prepared nanoparticles will be discussed here. 相似文献
8.
Chromium(VI) is a common heavy metal pollutant and extensively used in variety of industrial processes. In the present study, bismuth oxide–zirconium oxide nanocomposite (Bi 2O 3–ZrO 2) was synthesized to improve photoreduction of Cr(VI) under visible light irradiation. The synthesized photocatalyst was characterized by UV-visible-diffuse reflectance spectroscopy (UV-vis-DRS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (B.E.T) surface area analysis and photoluminescence spectroscopy (PL). Bi 2O 3–ZrO 2 was found to be more photoactive than Bi 2O 3, ZrO 2, TiO 2 and ZnO for the reduction of Cr (VI). The influences of various reaction parameters like the effect of catalyst concentration, initial Cr(VI) concentration and addition of inorganic salts on the photocatalytic activity have been investigated in detail. Meanwhile, the stability of Bi 2O 3–ZrO 2 was investigated by repeatedly performing Cr(VI) photoreducing experiments. 相似文献
9.
Vanadium (IV/V) doped rutile TiO 2 naonorods had been successfully synthesized through a single step hydrothermal method. The photocatalyst was characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV–vis diffusive reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The results showed that the doping of V ions had significant influence on the band gap energy and the surface state of TiO 2. The photo-activities of the new catalysts were investigated under ultraviolet (UV) and visible light. The UV-photocatalytic activity of the as-prepared catalysts was hardly influenced by doping V ions; while under visible light, the samples with 1 wt% and 0.1 wt% V exhibited enhanced activity to the oxidation of methylene blue (MB) and the reduction of Cr (VI), respectively. 相似文献
10.
In the present work, silver and sulphur codoped TiO 2 (Ag–S/TiO 2) photocatalysts were effectively prepared by sol–gel technique. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance UV–Vis spectroscopy (UV-DRS) and photoluminescence (PL). The XRD patterns consisted of anatase crystalline phases and the particle size and shape of the prepared samples were observed by SEM and HR-TEM. The presence of doping ions was confirmed by EDX analysis, the decreased band-gap energy of Ag–S codoped TiO 2 nanoparticles was investigated by UV-DRS. The decreased in the intensity of Ag–S codoped TiO 2 was absorbed due to the lower separation of electron–hole pairs were confirmed by PL spectrum. The Ag–S codoped TiO 2 showed higher photocatalytic activity than pure and single-doped TiO 2 in the photodegradation of methylene blue (MB) aqueous solution under visible light irradiation. The given work was a good model to associate the considering of the synergistic effect of metal and non-metal codoped TiO 2 in the photocatalysis and photo electrochemistry. 相似文献
11.
Zirconia and nitrogen-doped TiO 2 powder was synthesized using a polymer complex solution method for the preparation of an enhanced visible light photocatalyst. The produced catalysts were characterized via the Brunauer, Emmett, and Teller method (BET), X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, and UV–Vis spectrophotometry analyses. The N-doped TiO 2/ZrO 2 photocatalyst showed a high specific surface area and small crystal sizes. The XPS spectra of the N-doped TiO 2/ZrO 2 sample indicated that nitrogen was doped into the TiO 2 lattice and enhanced the photocatalytic activity. The UV–Vis absorption spectra of the N-doped TiO 2/ZrO 2 sample noticeably shifted to the visible light region compared to that of the TiO 2. The photocatalytic activities of the prepared catalysts were evaluated for the decomposition of gaseous NO x under UV and visible light irradiations. The photocatalytic activities of N-doped TiO 2/ZrO 2 were much greater than those of commercial Degussa P25 in both the UV and visible light regions. The high photocatalytic activity can be attributed to stronger absorption in the visible light region, a greater specific surface area, smaller crystal sizes, more surface OH groups, and to the effect of N-doping, which resulted in a lower band gap energy. 相似文献
12.
Synthesis of single phase cobalt-orthotitanate inverse spinel nano particles is reported for the first time via a novel solvothermal method at low calcination temperature at 400?°C. The pure phase cobalt-orthotitanate spinel nano particles were prepared using cobalt nitrate and titanium tetraisopropoxide (1:1 molar ratio) as cobalt and titanium sources. The synthesised Co 2TiO 4 nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, surface area analyses (Brauner–Emmett–Teller) (BET) and UV–Vis diffuse reflectance spectroscopy. The XRD results proved the formation of a single phase cobalt-orthotitanate (Co 2TiO 4) nanoparticles by calcination temperature of 400?°C. The FE-SEM results showed that nano particles possess a uniform spherical morphology with an average size of 51 nm. Porosity and specific surface area of cobalt-orthotitanate nano particles was measured by nitrogen adsorption using BET and the results showed surface area of 44.47 m 2/g. DRS results showed an optical band gap value of 1.802 eV for cobalt-orthotitanate nano powder. An excellent performance as a nano photo-catalyst toward the degradation of Remazol Red RB 133 (RR133) as a single azo textile dye with excellent efficiency. Mineralization of RR133 by highly active cobalt-orthotitanate nano-catalyst coated on glass surface was applied and 97% TOC removal was observed. This is due to high electron–hole charge separation and high surface area of nano-catalyst. 相似文献
13.
A new visible driven photocatalyst K 7Ti 2W 10PO 40/TiO 2 (KPW/TiO 2) with various KPW contents (2, 11 and 20 wt%) was successfully synthesized through a modified sol–gel-hydrothermal method. The structural properties of the prepared nanocomposite were characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared, photoluminescence spectroscopy and diffuse reflectance spectra (DRS). From the results obtained, the 11-KPW/TiO 2 showed the highest photocatalytic activity. Photoluminescence analysis for all synthesized samples showed that the 11-KPW/TiO 2 had the lowest intensity and recombination rate of photogenerated electron and holes. Tauc plots of the photocatalysts show that the presence of KPW in the x-KPW/TiO 2 nanocomposites reduced the band gap of nanocomposites, but the change in the amount of KPW have not a specific effect on the band gap reduction. It seems that the change in the loading of the KPW is effective on the amount of recombination of electron–hole. The absorption edge of the modified TiO 2 showed a red shift into the visible light range. Mott–Schottky plots show a positive slope as expected for n-type semiconductor. The prepared photocatalysts were examined for degradation of DR16 under visible light irradiation. The performance of the photocatalyst was analyzed and modeled by response surface methodology. Optimum conditions were DR16 conc. of 20 mg/L, reaction time 4 h, initial pH (3) and polyoxometalate loading 11 wt%. In order to assess the treatment capacity of the nanophotocatalyst, specific removal rate for the DR16 at all operating conditions were calculated. 相似文献
14.
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
15.
Iron-doped anatase titanium dioxide catalysts coated on glass-fiber were successfully synthesized by a dip-coating sol–gel method. The prepared catalysts were characterized by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy to understand the synthesis mechanism, and their photocatalytic activities were evaluated by photodegradation of phenol under simulated solar irradiation. EDX analysis confirmed the existence of iron in the immobilized catalysts. XRD suggested that the phase transition of the catalysts from anatase to rutile were restrained, and almost pure anatase TiO 2 could retain even the calcination temperature reached 800 °C. The UV-Vis diffuse reflectance spectroscopy of the catalysts showed a red shift and increased photoabsorbance in the visible range for all the doped samples. Iron loading and calcination temperature have obvious influences on photocatalytic activity. In this study, the optimal doping dose and calcination temperature were around 0.005 wt% and 600 °C, respectively. 相似文献
16.
TiO 2 nanotubes were synthesized by the solvothermal process at low temperature in a highly alkaline water–methanol mixed solution. Their characteristics were identified by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (BET), Fourier transform infrared spectroscopy (FTIR) and UV–Vis absorption spectroscopy. The as-prepared samples were tested by the photodegradation reaction of methylene blue (MB) dye under visible-light irradiation. The ratios of methanol and water, as well as calcination temperature, affected the morphology, nanostructure and photocatalytic performance. The methanol solvent plays an important role in improving crystallization of the anatase phase, which affects the photocatalytic reaction. Titanate nanotubes were synthesized in methanol–water volume ratios of 10:90, 20:80 and 30:70 which still had high absorbability. Titania nanotubes formed at a calcination temperature of 300 °C using methanol–water volume ratio of 30:70 showed highest photocatalytic performance, much higher than that using water solvent and TiO 2–P25 powder. 相似文献
17.
In this paper, TiO 2 nanoparticles were synthesized via sol–gel method by using of TiCl 4 as a precursor in the ethanol solution. The structure and the morphology of TiO 2 nanoparticles were characterized by X-ray diffraction and scanning electron microscopy. We have studied the optical properties by using of UV–Vis spectroscopy. The results show that the calcination temperature is an important factor in size of nanoparticles, the morphology of powders and the band gap energy of TiO 2 nanoparticles. Also, rapid cooling time of samples is an important factor to decrease band gap energies, considerably. The calculated band gap of the TiO 2 nanoparticles is in range of 2.39–3.50 eV. 相似文献
18.
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
19.
In this paper, we report on a nonaqueous synthesis of single crystalline anatase TiO 2 nanorods by reaction between TiCl 4 and benzyl alcohol at a low temperature of 80 °C. The resulting samples were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, nitrogen adsorption, X-ray photoelectron spectrometry and UV-vis diffuse reflectance spectroscopy. We proposed that the TiO 2 nanorods were formed through an oriented attachment mechanism. More importantly, these single crystalline anatase TiO 2 nanorods exhibited significantly higher photocatalytic activities than commercial photocatalyst P25. This study provides an environmentally friendly and economic approach to produce highly active TiO 2 photocatalyst. 相似文献
20.
Mesostructured ZrO 2–TiO 2 nanoparticles with different ZrO 2 contents have been synthesized by an ionic liquid-assisted hydrothermal route. The prepared materials were characterized by means of X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra analysis (DRS) and NH 3-TPD technique. The obtained ZrO 2–TiO 2 materials exhibit large specific surface area and uniform pore sizes. Introduction of ZrO 2 species can effectively suppress phase transformation from anatase to rutile and promote thermal stability of ZrO 2–TiO 2 materials. The photocatalytic activity of the ZrO 2–TiO 2 sample is higher than that of the TiO 2 sample and commercially available Degussa P25. The high photocatalytic activity can be attributed to stronger adsorption in the ultraviolet region, higher specific area, smaller crystal size and increased surface OH groups. 相似文献
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