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1.
In this work, the Er 3+:Y 3Al 5O 12 as up-conversion luminescence agent was mixed with TiO 2 and the corresponding Er 3+:Y 3Al 5O 12/TiO 2 composite films were prepared on the one-sided surface of treated sheet glass through sol-gel dip-coating method. The prepared Er 3+:Y 3Al 5O 12/TiO 2 composite films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Their photocatalytic activities were examined through the degradation of some organic dyes under visible-light irradiation. The degradation process of organic dyes was monitored by UV-Vis spectrophotometer. Furthermore, some main influence factors on the visible-light photocatalytic activity of Er 3+:Y 3Al 5O 12/TiO 2 composite film such as heat-treatment temperature and heat-treatment time were studied. The results indicate that three layer Er 3+:Y 3Al 5O 12/TiO 2 composite films with one Er 3+:Y 3Al 5O 12/TiO 2 composite film (as first layer close to sheet glass) and two pure TiO 2 film (as second and third layers) display a higher visible-light photocatalytic activity during photocatalytic degradation of Azo Fuchsine. In addition, the results showed that the visible-light photocatalytic activity of Er 3+:Y 3Al 5O 12/TiO 2 composite film related to the layer number and layer sequence on the sheet glass. Perhaps, the research results may offer some meaningful references for developing solar energy continuous flow wastewater treatment reactor. 相似文献
2.
In this study, Ag deposited TiO 2 (Ag/TiO 2) composites were prepared by three different methods (Ultraviolet Irradiation Deposition (UID), Vitamin C Reduction (VCR) and Sodium Borohydride Reduction (SBR)) for the visible-light photocatalytic degradation of organic dyes in magnetic field. And then the prepared Ag deposited TiO 2 (Ag/TiO 2) composites were characterized physically by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The visible-light photocatalytic activities of these three kinds of Ag deposited TiO 2 (Ag/TiO 2) composites were examined and compared through the degradation of several organic dyes under visible-light irradiation in magnetic field. In addition, some influence factors such as visible-light irradiation time, organic dye concentration, revolution speed, magnetic field intensity and organic dye kind on the visible-light photocatalytic activity of Ag deposited TiO 2 (Ag/TiO 2) composite were reviewed. The research results showed that the presence of magnetic field significantly enhanced the visible-light photocatalytic activity of Ag deposited TiO 2 (Ag/TiO 2) composites and then contributed to the degradation of organic dyes. 相似文献
3.
Ag/TiO 2 photocatalytic films were produced by hybrid sol-gel method. The photocatalytic degradation of methyl orange (MO) in aqueous
solution under 365 nm irradiation on TiO 2 and Ag/TiO 2 thin films was investigated. The state and amount of Ag species within the film and the enhancement mechanism of photocatalytic
activity of Ag/TiO 2 were discussed. With a loading molar ratio of Ag/Ti = 0.135 in TiO 2 film, the maximum catalytic efficiency was observed.
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Translated from Journal of Beijing Normal University (Natural Sciences), 2005, 41(6) (in Chinese) 相似文献
4.
Heterostructures play an important role not only in the manufacture of semiconductor devices, but also in the field of catalysis. Herein, we report the synthesis of PdO/TiO 2 and Pd/TiO 2 heterostructured nanobelts by means of a simple co‐precipitation method, followed by a reduction process using surface‐modified TiO 2 nanobelts as templates. The as‐obtained heterostructures were characterized by transmission electron microscopy, X‐ray photoelectron spectroscopy, and UV/Vis diffuse reflectance spectroscopy. PdO and Pd nanoparticles with a size of about 1.3 and 1.6 nm were assembled uniformly on the surface of TiO 2 nanobelts, respectively. Compared with TiO 2 nanobelts, PdO/TiO 2 and Pd/TiO 2 hybrid nanobelts exhibit enhanced photocatalytic activity upon UV and visible‐light irradiation. Photoelectrochemical technology was used to study the heterostructure effect on enhanced photocatalytic activity. Our mechanistic investigation revealed that energy‐band matching is the major factor in the observed enhancement of photocatalytic activity. 相似文献
5.
The photocatalytic degradation of azo dyes with different structures (amaranth, sunset yellow and tartrazine) using TiO 2-Pt nanoparticles (TPt), TiO 2-Pt/graphene oxide (TPt-GO) and TiO 2-Pt/reduced graphene oxide (TPt-rGO) composites were investigated in the presence of UV and natural sunlight irradiation. The composites were prepared by a combined chemical-thermal method and characterized by Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Infrared (FTIR) and UV–Vis spectroscopy. The modification of TiO 2-Pt with graphene oxide shifted its optical absorption edge towards the visible region and increased its photocatalytic activity under UV and natural sunlight irradiation. The efficiency of catalysts on azo dyes degradation (in similar conditions) reached high values (above 99%) under sunlight conditions, proving the remarkable photocatalytic activities of obtained composites. TPt-GO nanocomposite exhibited higher photoactivity than TPt or TPt-rGO, demonstrating degradation efficiencies of 99.56% for amaranth, 99.15% for sunset yellow and 96.23% for tartrazine. The dye photodegradation process follows a pseudo-first-order kinetic with respect to the Langmuir-Hinshelwood reaction mechanism. A direct dependence between azo dyes degradation rate and chemical structure of dyes has been observed. 相似文献
6.
The photocatalytic activity of TiO 2 nanoparticles (nano‐TiO 2) and its hybrid with SiO 2 (nano‐TiO 2–SiO 2) for degradation of some organic dyes on cementitious materials was studied in this work. Nanohybrid photocatalysts were prepared using an inorganic sol–gel precursor and then characterized using XRD, SEM and UV–Vis. The grain sizes were estimated by Scherrer's equation to be around 10 nm. Then, a thin layer was applied to Portland cement concrete (PCC) blocks by dipping them into nano‐TiO 2 and nano‐TiO 2–SiO 2 solution. The efficiency of coated PCC blocks for the photocatalytic decomposition of two dyes, Malachite Green oxalate (MG) and Methylene Blue (MB), was examined under UV and visible irradiation and then monitored by the chemical oxygen demand tests. The results showed that more than 80% and 92% of MG and MB were decomposed under UV–Vis irradiation using blocks coated with nano‐TiO 2–SiO 2. TiO 2/PCC and TiO 2–SiO 2/PCC blocks showed a significant ability to oxidize dyes under visible and UV lights and TiO 2–SiO 2/PCC blocks require less time for dye degradation. Based on these results, coated blocks have increased photocatalytic activity which can make them commercially accessible photocatalysts. 相似文献
7.
Semiconductor photocatalysis is a process that harnesses light energy in chemical conversions. In particular, its applications to environmental remediation have been intensively investigated. The characteristics of TiO 2, the most popular photocatalyst, is briefly described and selected studies on the degradation/conversion of various recalcitrant pollutants using pure and modified TiO 2 photocatalysts, which were carried out in this group, are reviewed. Photocatalytic reactions are multi-phasic and take place at interfaces of not only water/TiO 2 and air/TiO 2 but also solid/TiO 2. Examples of photocatalytic reactions of various organic and inorganic substrates that are converted through the photocatalytic oxidation or reduction are introduced. TiO 2 has been modified in various ways to improve its photocatalytic activity. Surface modifications of TiO 2 that include surface platinization, surface fluorination, and surface charge alteration are discussed and their applications to pollutants degradation are also described in detail. 相似文献
8.
PPy@TS nanocomposite with enhanced photocatalytic capability was prepared by in situ polymerizing polypyrrole on the surface of TiO 2/SiO 2 nanofibrous membrane. 相似文献
9.
We successfully prepared Ag quantum dots modified TiO 2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO 2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO 2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO 2 microspheres for methyl orange degradation was proposed in detail. 相似文献
10.
This study was focused on the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe–TiO 2) composites for the degradation of methylene blue as a model dye. TiO 2 nanoparticles were doped with iron ions (Fe) using the wet impregnation method and the doped nanoparticles were further combined with Pani via an in situ polymerization method. For comparison purposes, Pani composites were also synthesized in the presence undoped TiO 2. The photocatalyst and the composites were characterized by standard analytical techniques such as FTIR, XRD, SEM, EDX and UV–Vis spectroscopies. Fe–TiO 2 and its composites exhibited enhanced photocatalytic activity under ultraviolet light irradiation. Improved photocatalytic activity of Fe–TiO 2 was attributed to the dopant Fe ions hindering the recombination of the photoinduced charge carriers. Pani/Fe–TiO 2 composite with 30?wt.% of TiO 2 nanoparticles achieved 28% dye removal and the discoloration rate of methylene blue for the sample was 0.0025?min ?1. FTIR, XRD, SEM, EDX and UV–Vis spectroscopies supported the idea that Fe ions integrated into TiO 2 crystal structure and Pani composites were successfully synthesized in the presence of the photocatalyst nanoparticles. The novelty of this study was to investigate the photocatalytic activity of Pani composites, containing iron doped TiO 2 and to compare their results with that of Pani/TiO 2. 相似文献
11.
The Er 3+:Y 3Al 5O 12, as an upconversion luminescence agent which is able to transform the visible part of the solar light to ultraviolet light, was prepared by nitrate-citrate sol-gel method. A novel solar light photocatalyst, Er 3+:Y 3Al 5O 12/TiO 2-CeO 2 composite was synthesized using ultrasonic treatment. The X-ray diffraction (XRD) and scanning election microscopy (SEM) were used to characterize the structural morphology of the Er 3+:Y 3Al 5O 12/TiO 2-CeO 2 composite. In order to evaluate the solar light photocatalytic activity of Er 3+:Y 3Al 5O 12/TiO 2-CeO 2 composite, the Azo Fuchsine dye was used as a model organic pollutant. The progress of the degradation reaction was monitored by UV-Vis spectroscopy and ion chromatography. The key influences on the solar light photocatalytic activity of Er 3+:Y 3Al 5O 12/TiO 2-CeO 2 were studied, such as Ti/Ce molar ratio, heat-treatment temperature and heat-treatment time. Otherwise, the effects of initial dye concentration, Er 3+:Y 3Al 5O 12/TiO 2-CeO 2 amount, solar light irradiation time and the nature of the dye on the solar light photocatalytic degradation process were investigated. It was found that the solar light photocatalytic activity of Er 3+:Y 3Al 5O 12/TiO 2-CeO 2 composite was superior to Er 3+:Y 3Al 5O 12/TiO 2 and Er 3+:Y 3Al 5O 12/CeO 2 powder in the similar conditions. 相似文献
12.
Constructing nanocomposites that combine the advantages of composite materials, nanomaterials, and interfaces has been regarded as an important strategy to improve the photocatalytic activity of TiO 2. In this study, 2D-2D TiO 2 nanosheet/layered WS 2 (TNS/WS 2) heterojunctions were prepared via a hydrothermal method. The structure and morphology of the photocatalysts were systematically characterized. Layered WS 2 (~4 layers) was wrapped on the surface of TiO 2 nanosheets with a plate-to-plate stacked structure and connected with each other by W=O bonds. The as-prepared TNS/WS 2 heterojunctions showed higher photocatalytic activity for the degradation of RhB under visible-light irradiation, than pristine TiO 2 nanosheets and layered WS 2. The improvement of photocatalytic activity was primarily attributed to enhanced charge separation efficiency, which originated from the perfect 2D-2D nanointerfaces and intimate interfacial contacts between TiO 2 nanosheets and layered WS 2. Based on experimental results, a double-transfer photocatalytic mechanism for the TNS/WS 2 heterojunctions was proposed and discussed. This work provides new insights for synthesizing highly efficient and environmentally stable photocatalysts by engineering the surface heterojunctions. 相似文献
13.
Melamine was added to the precursor of TiO2, then TiO2 prepared by hydrothermal, while melamine was modified. Subsequently, a series of Z-scheme TiO2/g-C3N4 heterojunction composites were successfully synthesized by simple calcination. The morphology and structure of samples were characterized by XRD, FT-IR, UV–vis DRS, SEM, TEM, PL and BET. The photocatalytic activity of these samples has been investigated by degradation of Rhodamine B (RhB), and results indicated that photocatalytic activity of the as-prepared samples was greatly influenced by the content of titanium tetrabutoxide in precursors and the hydrothermal time. The degradation rate of TiO2/g-C3N4-1 to RhB was the best, which was 5.05-fold of pure TiO2 (19.61%) and 2.25-fold of bulk g-C3N4 (44.06%), respectively. The trapping experiment results showed that ·O2? and h+ were main active species during degradation of RhB. The photocatalytic activity of the sample did not decrease significantly after 4 cycles. The unique Z-scheme heterojunction between TiO2 and g-C3N4 improved photocatalytic activity of the samples under visible light. 相似文献
14.
The application of photocatalytic coatings on stone has been investigated for providing surface protection and self-cleaning
properties. Sol–Gel and hydrothermal processes were used to synthesise TiO 2 colloidal suspensions and coatings with enhanced photocatalytic activity without any thermal curing of the coated stone.
The stone was a porous limestone (apulian sedimentary carbonatic, calcite stone). Films and powders prepared from TiO 2 sols were studied using X-ray diffraction to evaluate the microstructure and identify rutile and anatase phases. A morphological
and physical characterisation was carried out on coated and uncoated stone to establish the changes of appearance, colour,
water absorption by capillarity and water vapour permeability. The photocatalytic activity of the coated surface was evaluated
under UV irradiation through NO
x
and organics degradation tests. The performances of the synthesised TiO 2 sols were compared with commercial TiO 2 suspension. Since the coating doesn’t need temperature treatments for activating the photocatalytic properties, the nano-crystalline
hydrothermal TiO 2 sols seem good candidate for coating applications on stone that cannot be annealed after the coating application. 相似文献
15.
Direct Z-scheme g-C 3N 4/TiO 2 nanorod composites were prepared for enhancing photocatalytic activity for pollutant removal. The characterization revealed that the g-C 3N 4/TiO 2 nanorod composite formed a close interface contact between g-C 3N 4 and TiO 2 nanorods, which was of benefit for the charge transfer and resulted in its high photocatalytic activity. The g-C 3N 4/TiO 2 nanorod composites exhibited higher photocatalytic activity for degradation of Rhodamine B (RHB) than bare g-C 3N 4 and TiO 2 nanorods. The high photocatalytic activity of g-C 3N 4/TiO 2 nanorod composites is attributed to the formation of the direct Z-scheme system, in which the electrons from the conduction band (CB) of TiO 2 combine with the holes from the valence band (VB) of C 3N 4 while the electrons from the CB of C 3N 4 and holes from the VB of TiO 2 with stronger redox ability are used to reduce and oxidize pollutants. Based on the radical-trapping experiments, the main reactive species for RHB degradation are O 2− and · OH, which are produced by photoinduced electrons and holes with high redox ability. This work provides insights into the photocatalytic mechanism of composite materials for the photocatalytic removal of organic pollutants. 相似文献
16.
In order to improve the catalytic activity of Fenton catalyst, a composite catalyst, Fe/TiO 2, with both visible-light photocatalytic and Fenton-like catalytic activities was synthesized via a brief solvothermal process. The XRD and SEM results indicated that Fe was dispersed homogeneously on the surface of TiO 2 in the form of Fe 2O 3, and the loading of Fe did not have significant effects on the particle size and morphology of TiO 2. The EDS results showed that the loading content of Fe was about 1.4 wt%. The photocatalytic results showed that the prepared Fe/TiO 2 composite catalyst had excellent catalytic behaviors for terbuthylazine degradation under visible-irradiation with H 2O 2 assistance, the degradation ratio reached up to 90% after 120 min. The reinforced degradation performance were primarily attributable to the introduction of carrier TiO 2, which expanded visible response range by H 2O 2 adsorption, and accelerated the cycle of Fe (Ⅱ)/Fe (Ⅲ). The fluorescent spectroscopy results revealed that the degradation process of terbuthylazine involved the generation and participation of active species such as hydroxyl radicals and superoxide radicals. This study is expected to provide a visual approach for designing a novel photo-Fenton catalyst to jointly utilize both photocatalytic and Fenton activities, which can be better applied to the actual use of organics purification in wastewater. 相似文献
17.
本文采用溶胶-凝胶法制备了Zr离子掺杂TiO 2光催化剂。光催化降解对氯苯酚实验表明,Zr离子掺杂浓度为10%时活性最高,其紫外光、可见光催化活性分别是纯TiO 2的1.5倍和4倍。利用XRD、Raman、XPS、UV-Vis DRS、PL等技术对样品进行了表征,结果表明:Zr离子以取代式掺杂方式进入TiO 2晶格,在TiO 2导带下方形成掺杂能级,增强了可见光响应,促进了光生载流子的分离,此外Zr离子掺杂在催化剂表面引入大量表面缺陷,增加了表面羟基物种,从而使得Zr离子掺杂TiO 2光催化剂的紫外、可见光催化活性显著提高。 相似文献
18.
Erbium co‐doped TiO 2/Ag catalysts are synthesized by using a simple, one‐step solvothermal method and characterized by X‐ray diffraction, field‐emission scanning electron microscopy, transmission electron microscopy, Raman analysis, X‐ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The catalysts exhibit anatase crystal structures with increased visible light absorption compared with pure TiO 2. Enhanced photocatalytic activity is observed with Er co‐doped TiO 2/Ag nanocomposites for Rhodamine B degradation under visible light irradiation. The photocatalytic activity of 1 % Er co‐doped TiO 2/Ag is much higher than that of TiO 2/Ag, TiO 2/Er, pure TiO 2, and commercial Degussa P25. The kinetics of the degradation process are studied and the pseudo‐first‐order rate constant ( k) and half‐life time ( t1/2) of the reaction are calculated. The enhanced activity might be accredited to the efficient separation of electron–hole pairs by silver and higher visible light absorption of TiO 2 induced by Er. 相似文献
19.
In this article, TiO 2 nanorods (aspect ratio >20) were prepared through a polyol process and doped with metal ions (Cu 2+, Ni 2+, Fe 3+, and Cr 3+). Compared with TiO 2 nanoparticles, the TiO 2 nanorods displayed relatively higher photocatalytic activity for the degradation of copper sulfophthalocyanine. Moreover, the photocatalytic activity was greatly enhanced when the metal ions were doped in the TiO 2 nanorods. 相似文献
20.
A series of B, Ce co-doped TiO 2 (B, Ce-TiO 2) photocatalytic materials with a hollow fiber structure were successfully prepared by template method using boric acid, ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500°C in an N 2 atmosphere for 2 h. Scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption-desorption measurements, and UV-visible spectroscopy (UV-Vis) were employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photocatalytic performance of the samples was studied by photodegradation phenol in water under UV light irradiation. The results showed that the TiO 2 fiber materials have hollow structures, and the fiber structure materials showed better photocatalytic properties for the degradation of phenol than pure TiO 2 under UV light. In the experiment condition, the photocatalytic activity of B, Ce co-doped TiO 2 fibers was optimal of all the prepared samples. In addition, the possibility of cyclic usage of B, Ce co-doped TiO 2 fiber photocatalyst was also confirmed, the photocatalytic activity of TiO 2 fibers remained above 90% of that of the fresh sample after being used four times. The material was easily removed by centrifugal separation from the medium. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants. 相似文献
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