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1.
HyunSeock Jie Ho-bum Lee Keun-Hwa Chae Moo-Young Huh Masaya Matsuoka So-Hye Cho Jong-Ku Park 《Research on Chemical Intermediates》2012,38(6):1171-1180
During chemical vapor synthesis of TiO2 nanopowders, nitrogen atoms were doped into the crystal lattice of TiO2. The nitrogen atoms were predominantly incorporated substitutionally in the crystal lattice of TiO2 nanopowders up to the doping level of 1.25 mol% nitrogen, whereas they were in both interstitial and substitutional sites
over about 1.43 mol% nitrogen. From the photocatalytic activity of nitrogen-doped TiO2 estimated by decomposition of methylene blue under visible light, it was found that the substitutional nitrogen anions appearing
at the low level doping was beneficial to its photocatalytic activity, whereas the interstitial ones appearing at the high
level doping over 1.25 mol% nitrogen were not. The improved photocatalytic activity due to the substitutionally doped nitrogen
was attributed to band gap narrowing which was confirmed by the studies of XPS, near edge X-ray absorption fine structure,
and UV–Vis absorption. 相似文献
2.
Undoped and Ce(4+) doped TiO2 thin films were prepared by sol-gel method. The samples were characterized using scanning electron microscopy, the photocatalytic
reactivity was evaluated by degradation of methylene blue in the aqueous solution. 0.5 wt. % Ce(4+) doped TiO2 thin films calcined at 400°C show the highest photocatalytic activity.
The text was submitted by the authors in English. 相似文献
3.
Bhaskar Soman Swapna Challagulla Soumitra Payra Srikanta Dinda Sounak Roy 《Research on Chemical Intermediates》2018,44(4):2261-2273
The main aim of this work is to discriminate the closely related adsorption and catalytic degradation processes that occur during a photocatalytic reaction. Very high-surface-area TiO2 and Pd-doped TiO2 were synthesized by microwave-assisted hydrothermal synthesis and used for degradation of methylene blue as a model pollutant dye. Thorough structural, morphological, and surface analyses of the synthesized catalysts were conducted to investigate key material properties that influence adsorption and catalytic performance. The adsorption capacity of the catalysts was determined by fitting adsorption data using the Langmuir isotherm model, and the photocatalytic activity of the synthesized samples was evaluated by periodically measuring the concentration of methylene blue as it was photocatalytically degraded under ultraviolet (UV) light. The results indicated that noble-metal incorporation compromised adsorption but favored catalytic performance. 相似文献
4.
Uraiwan Sirimahachai Nicholas Ndiege Ramesh Chandrasekharan Sumpun Wongnawa Mark A. Shannon 《Journal of Sol-Gel Science and Technology》2010,56(1):53-60
Nanosized TiO2 and nano-anatase TiO2 decorated on SiO2 spherical core shells were synthesized by using a sol–gel method. The synthesized pure TiO2 nano particle and TiO2 grafted on SiO2 sphere with various ratios have been characterized for their structure and morphologies by X-ray diffraction (XRD), X-ray
photoelectron spectroscopy (XPS), Fourier transform infrared spectrophotometry (FTIR) and transmission electron microscopy
(TEM). Their surface areas were measured using the BET method. The photocatalytic activity of all nanocomposites was investigated
using methylene blue as a model pollutant. The synthesized TiO2/SiO2 particles appeared to be more efficient in the degradation of methylene blue pollutant, as compared to pure TiO2 particles. 相似文献
5.
In this study, titanium tetra‐isopropoxide was used as a precursor of TiO2 for in situ coating on cotton fabric by sol–gel method. Subsequently, silver nitrate was used as doping agent to prepare silver‐doped TiO2‐coated cotton fabric during hydrothermal treatment. The treated samples were characterized through field‐emission scanning electron microscopy, energy‐dispersive X‐ray analysis, inductively coupled plasma‐mass spectroscopy and UV–visible absorption spectroscopy to study morphology, composition of deposited elements and light absorption behavior of treated samples. X‐ray photoelectron spectroscopy was carried out to analyze the electronic state of silver in TiO2‐coated fabric after hydrothermal treatment. Doping of silver on TiO2‐coated fabric and subsequent hydrothermal treatment was found to enhance dye decolorization rate of rhodamine B dye solution in both UV and visible light radiations with respect to undoped TiO2. The study shows that an optimal level of silver‐doped TiO2‐coated fabric can be used repeatedly for dye decolorization without significant loss in its photocatalytic activity. The self‐cleaning properties of samples were also studied using methylene blue as a staining agent. It was observed that the presence of 1.8% silver on the weight of titanium in doped samples provides almost 82% of stain degradation. 相似文献
6.
Preparation of nanocrystalline Fe-doped TiO<Subscript>2</Subscript> powders as a visible-light-responsive photocatalyst 总被引:1,自引:0,他引:1
Nanocrystalline Fe-doped TiO2 powders were prepared using TiOSO4, urea, and Fe(NO3)3 · 9H2O as precursors through a hydrothermal method. The as-synthesized yellowish-colored powders are composed of anatase TiO2, identified by X-ray diffraction (XRD). The grain size ranged from 9.7 to 12.1 nm, calculated by Scherrer’s method. The specific
surface area ranged from 141 to 170 m2/g, obtained by the Brunauer–Emmett–Teller (BET) method. The transmission electron microscopy (TEM) micrograph of the sample
shows that the diameter of the grains is uniformly distributed at about 10 nm, which is consistent with that calculated by
Scherrer’s method. Fe3+ and Fe2+ have been detected on the surface of TiO2 powders by X-ray photoelectron spectroscopy (XPS). The UV–Vis diffuse reflection spectra indicate that the light absorption
thresholds of the Fe-doped TiO2 powders have been red-shifted into the visible light region. The photocatalytic activity of the Fe-doped TiO2 was evaluated through the degradation of methylene blue (MB) under visible light irradiation. The Fe-doped TiO2 powders have shown good visible-light photocatalytic activities and the maximum degradation ratio is achieved within 4.5 h. 相似文献
7.
M. E. de Anda Reyes G. Torres Delgado R. Castanedo Pérez J. Márquez Marín O. Zelaya Ángel 《Journal of Sol-Gel Science and Technology》2012,61(2):310-315
TiO2 thin films were obtained on glass slide substrates by the sol–gel technique. The substrates were coated by the immersion-removal
method, at a constant withdrawal speed. The TiO2 precursor solution and the substrate were maintained in a closed box with a controlled relative humidity (RH) during the
removal of the substrate. The RH was varied in the 30–90% range in steps of 20%. The films were dried and after that sintered
in an open atmosphere. The effect of the RH was studied on the structural, optical and photocatalytic properties. The films
are polycrystalline with an anatase phase and show a high optical transmission in the UV–Vis range. The photocatalytic activity
was evaluated by the photobleaching of methylene blue in an aqueous solution. The best photocatalytic activity was obtained
for the films with 90% RH, this fact is mainly attributed to the highest porosity value obtained for these films. 相似文献
8.
SiO2/TiO2 hybrid nanofibers were prepared by electrospinning and applied for photocatalytic degradation of methylene blue (MB). The phase structure, specific surface area, and surface morphologies of the SiO2/TiO2 hybrid nanofibers were characterized through thermogravimetry (TG), X-ray diffraction (XRD) analysis, Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), etc. XRD measurements indicated that doping of silica into TiO2 nanofibers can delay the phase transition from anatase to rutile and decrease the grain size. SEM and BET characterization proved that silica doping can remarkably enhance the porosity of the SiO2/TiO2 hybrid nanofibers. The MB adsorption capacity and photocatalytic activity of the SiO2/TiO2 hybrid nanofibers were distinguished experimentally. It was found that, although increased silica doping content could enhance the MB adsorption capacity, the intrinsic photocatalytic activity gradually dropped. The SiO2 (10 %)/TiO2 composite nanofibers exhibited the highest MB degradation rate, being superior to SiO2 (20 %)/TiO2 or pure TiO2. 相似文献
9.
Lixue Deng Yinglei Chen Meiyu Yao Shurong Wang Baolin Zhu Weiping Huang Shoumin Zhang 《Journal of Sol-Gel Science and Technology》2010,53(3):535-541
B-doped TiO2 nanotubes (B/TiO2 NTs) were prepared by the combination of sol–gel process with hydrothermal treatment. The prepared catalysts were characterized
by XRD, TEM and XPS. The photocatalytic activity of B/TiO2 NTs was evaluated through the photodegradation of aqueous methyl orange. The results demonstrated that the 1.5% B/TiO2 NTs calcined at 300 °C possessed the best photocatalytic activity. Compared with pure TiO2 nanotubes, the doping with B significantly enhanced the photocatalytic efficiency. 相似文献
10.
A comparative study of TiO2 powders prepared by sol–gel methods is presented. Titanium tetraisopropoxide was used as the precursor for the sol–gel processes.
The effects of the annealing treatment on phase, crystallite size, porosity and photodegradation of dyes (methyl orange and
methylene blue) were studied. The phase structure, microstructure and surface properties of the films were characterized by
using X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). The X-ray diffraction was used for crystal phase identification,
for the accurate estimation of the anatase–rutile ratio and for the crystallite size evaluation of each polymorph in the samples.
It was found that the only TiO2 anatase phase of the synthesized TiO2 develops below 500 °C, between 600 and 800 °C the anatase coexist with rutile and above 800 °C only the rutile phase was
found in the samples. Attention has been paid not only to crystal structures, but also to the porosity, the particle size
and the photocatalytic properties. However, the annealing temperature was found to have significant influence on the photocatalytic
properties. Different TiO2 doctor blade thin films were obtained mixing the sol gel powder (100% anatase) and TiO2 Aldrich with TiO2 Degussa P25. The surfactant (Triton X100 or sodium dodecyl sulfate) affects the packing density of the particles during deposition
and the photocatalytic degradation efficiency of the dyes. The photocatalytic degradation kinetics of methyl orange and methylene
blue using TiO2 thin film were investigated. 相似文献
11.
The structural properties of Au/TiO2 catalyst were studied by X-ray diffraction, UV-visible diffuse reflectance, photoluminescene, scanning transmission and electron
microscope, and temperature programmed reduction. The photocatalytic activity of the catalysts was evaluated for the degradation
of various azo-dyes such as methylene blue, methyl orange, reactive blue-4, and eosin-B under solar irradiation. It was found
that TiO2 catalyst modified with gold exhibits higher percentage of degradation compared to starting TiO2. For example, TiO2 showed 35% of methyl orange degradation whereas gold modified TiO2 possessed 82%. Effect of different parameters such as pH and dye concentration has been evaluated and the photocatalytic
activity was correlated with physico-chemical properties. The dye degradation rate followed first order kinetics. 相似文献
12.
Gobinda Gyawali Jieun Son Nguyen Huy Hao Sung Hun Cho Tae-Ho Kim Soo Wohn Lee 《Research on Chemical Intermediates》2017,43(9):5055-5065
TiO2 nanotubes (TNTs) were successfully synthesized from different alkaline media (i.e., NaOH and KOH) by using a microwave hydrothermal process. The effects of different alkaline media on the formation of TiO2 nanotubes and their physicochemical properties were investigated. The phases of different TiO2 nanostructures were studied by using X-ray diffraction patterns. Morphologies of the nanostructures were observed with a transmission electron microscope. The optical properties of the nanostructures were evaluated through the absorption behavior using UV–Vis diffuse reflectance spectroscopy. The photocatalytic activities of the TiO2 nanostructures were evaluated by the degradation of methylene blue aqueous dye solution under the simulated solar light irradiation. Similarly, the photovoltaic efficiencies of the prepared samples were investigated by making photo-anode layers in the Dye Sensitized Solar Cells (DSSCs). The results revealed that in comparison to the single layered TiO2 nanostructures in the DSSC, creation of a double layer structure significantly enhanced the efficiency of DSSC. 相似文献
13.
A series of tungsten‐doped Titania photocatalysts were synthesized using a low‐temperature method. The effects of dopant concentration and annealing temperature on the phase transitions, crystallinity, electronic, optical, and photocatalytic properties of the resulting material were studied. The X‐ray patterns revealed that the doping delays the transition of anatase to rutile to a high temperature. A new phase WyTi1‐yO2 appeared for 5.00 wt% W‐TiO2 annealed at 900 °C. Raman and diffuse reflectance UV–Vis spectroscopy showed that band gap values decreased slightly up to 700 °C. X‐ray photoelectron spectroscopy showed that surface species viz. Ti3+, Ti4+, O2?, oxygen‐vacancies, and adsorbed OH groups vary depending on the preparation conditions. The photocatalytic activity was evaluated via the degradation of methylene blue using LED white light. The degradation rate was affected by the percentage of dopants. The best photocatalytic activity was achieved with the sample labeled 5.00 wt% W‐TiO2 annealed at 700 °C. 相似文献
14.
Shujuan Zhang Limin Song Shuna Zhang Donglan Sun Bin Chen 《Reaction Kinetics and Catalysis Letters》2009,97(2):199-205
S–N-codoped TiO2 powders have been synthesized through a facile one-step sol–gel method by using tetrabutyltitanate and thiourea as precursors.
The S–N-codoped TiO2 treated at 500 °C showed the highest photocatalytic activity for degrading methylene blue under visible light irradiation.
XRD, XPS and UV–vis studies revealed that the high visible-light photocatalytic activity of the doped TiO2 may originate from the synergetic effect of sulfur and nitrogen codoping into TiO2. 相似文献
15.
Dieqing Zhang Xiaolei Yang Jian Zhu Ya Zhang Peng Zhang Guisheng Li 《Journal of Sol-Gel Science and Technology》2011,58(3):594-601
Graphite-like carbon deposited single-crystal anatase TiO2 with exposed {001} facets was fabricated through a two-step solvothermal process by using glucose as carbon source. The physicochemical
properties of the as-prepared samples were investigated by X-ray diffraction, Brunauer-Emmett-Teller, transmission electron
microscopy, Raman, UV–vis diffuse reflectance spectra, electrochemical impedance spectroscopy and surface photovoltage spectroscopy.
These results demonstrated that graphite-like carbon layers were deposited on the surface of TiO2 single-crystal nanosheets with exposed highly reactive {001} facets via the dehydration of glucose during the process of
hydrothermal treatment. The loading of the graphite-like carbon layers could effectively extend the light absorption edge
of the single-crystal anatase TiO2 nanosheets to visible light region and accelerate the separation of photo-generated electrons and holes, contributing an
excellent visible-light driven photocatalytic performance to the graphite-like carbon deposited single-crystal anatase TiO2 nanosheets for the degradation of methyl orange. 相似文献
16.
Coal cinder-supported TiO2 photocatalysts were synthesized via a novel coal combustion method. As-obtained samples were characterized by XRD, SEM, EDS mapping, Raman spectra, FTIR and DRS, and their photocatalytic performances were evaluated by degradation of methylene blue (MB) and methyl orange (MO) under UV–Vis light illumination. The results revealed that mixed-phases TiO2 with adjustable anatase–rutile ratio could be obtained by adjusting the amount of precursor tetrabutyl titanate, which was uniformly covered on the coal cinder. These coal cinder-supported TiO2 photocatalysts exhibited commendable photocatalytic activity. Among them, the indexed CCT-7.5 sample presented the maximum of activity, which can be attributed to the optimal phase composition of TiO2. The present work provided a novel synthetic route to fabricate immobilized photocatalysts, which might be extended to the preparation of other functional materials. 相似文献
17.
O. Vázquez-Cuchillo A. Cruz-López L. M. Bautista-Carrillo A. Bautista-Hernández L. M. Torres Martínez S. Wohn Lee 《Research on Chemical Intermediates》2010,36(1):103-113
In this work, various TiO2 and TiO2 doped with 0.1, 1.0, and 5.0 mol% of Zn were prepared by the sol–gel method varying different hydrolysis catalysts (HNO3, OHAc, H3PO4) in order to be used as photocatalysts for environmental applications. The X-ray diffraction results showed that the different
TiO2 samples have presented the anatase as main phase, However, the acid nature has played an important role in the superficial
and optical properties. The N-physisortion analysis has revealed that the specific surface area of calcined TiO2 samples prepared using H3PO4, HOAc, and HNO3 was 245, 100, and 90 m2 g−1, respectively, while the spectroscopic UV analysis, the band gap energy has shifted by 3.3–3.0 eV. In order to improve the
optical properties of TiO2, the last preparation was doped with different zinc concentrations. The result showed that, as the Zn concentration increase
by 0.1–5.0 mol%, the surface area increased from 90 to 120 m2 g−1. Nevertheless, the E
g returned from 3.0 to 3.32. The SEM analyses have not revealed important morphological changes between no doped and doped
materials. The catalytic activity of the composite was studied on the photocatalytic degradation of 2,4-Dichlorophenoxyacetic
acid (2,4-D) and the activity results showed that small Zn concentrations decrease the t
1/2 in 28 min. 相似文献
18.
Behzad Koozegar Kaleji 《Journal of Sol-Gel Science and Technology》2013,67(2):312-320
The thin films of TiO2 doped by Sn or Nb were prepared by sol–gel method under process control. The effects of Sn and Nb doping on the structural, optical and photo-catalytic properties of applied thin films have been studied by X-ray diffraction (XRD) high resolution transmission electron microscopy and UV–Vis absorption spectroscopy. Surface chemical state of thin films was examined by atomic X-ray photoelectron spectroscopy. XRD results suggest that adding impurities has a great effect on the crystallinity and particle size of TiO2. Titania rutile phase formation in thin film was promoted by Sn4+ addition but was inhibited by Nb5+ doping. The activity of the photocatalyst was evaluated by photocatalytic degradation kinetics of aqueous methylene blue under UV and Visible radiation. The results show that the photocatalytic activity of the Sn-doped TiO2 thin film have a larger degradation efficiency than Nb-doped TiO2 under visible light, but under UV light photocatalytic activity of the Nb-doped TiO2 thin film is better. 相似文献
19.
Nitrogen-doped titanium dioxide (N-doped TiO2) photocatalysts were prepared by a mechanochemical method by using a high-speed ball milling of P25 TiO2 with nitrogen sources such as ammonia solution, hexamine, and urea. Visible-light absorption was determined from the onset
of diffused reflectance spectrum. The photocatalytic activity of the N-doped TiO2 was evaluated through the removal of methylene blue (MB) under visible-light irradiation. The effects of nitrogen precursors
used during the mechanochemical synthesis on the catalysts’ properties, such as the effective particle size, surface area,
and photocatalytic activity, were extensively investigated. 相似文献
20.
A series of composites containing hexagonal tungsten trioxide (h-WO3) and reduced graphene oxide (rGO) sheets are synthesized via a modified one-step hydrothermal route without assisted additive. The composites are characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectroscopy. The new procedure made it possible to increase the reduction degree of GO. Based on the evidence presented hexagonal WO3 grows on the surface of graphene through chemical interactions with the surface. The visible-light photocatalytic degradation of methylene blue shows that the h-WO3/rGO composites exhibit superior photocatalytic performance of 96% with a maximum degradation rate achieved under visible-light irradiation for 6 h. The speculations concerning the mechanism of photocatalytic reactions are discussed. The improved photocatalytic activity can be accounted for by the increased adsorption toward chemical species, the enhanced light absorption and an efficient separation of photogenerated electron-hole pairs and transfer of charge carriers. 相似文献