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1.
Hierarchical macro‐/mesoporous N‐doped TiO2/graphene oxide (N‐TiO2/GO) composites were prepared without using templates by the simple dropwise addition mixed solution of tetrabutyl titanate and ethanol containg graphene oxide (GO) to the ammonia solution, and then calcined at 350 °C. The as‐prepared samples were characterized by scanning electron microscopy (SEM), Brunauer‐Emmett‐Teller (BET) surface area, X‐ray diffraction (XRD), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and UV‐Vis absorption spectroscopy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange in an aqueous solution under visible‐light irradiation. The results show that N‐TiO2/GO composites exhibited enhanced photocatalytic activity. GO content exhibited an obvious influence on photocatalytic performance, and the optimal GO addition content was 1 wt%. The enhanced photocatalytic activity could be attributed to the synergetic effects of three factors including the improved visible light absorption, the hierarchical macro‐mesoporous structure, and the efficient charge separation by GO.  相似文献   

2.
A hierarchical macro‐/mesoporous Ce0.49Zr0.37Bi0.14O1.93 solid‐solution network has been synthesized on a large scale by means of a simple and general polymerization–carbonization–oxidation synthetic route. The as‐prepared product has been characterized by SEM, XRD, TEM, BET surface area measurement, UV/Vis diffuse‐reflectance spectroscopy, energy‐dispersive X‐ray spectroscopy (EDS), and photoelectrochemistry measurements. The photocatalytic activity of the product has been demonstrated through the photocatalytic degradation of methyl orange. Structural characterization has indicated that the hierarchical macro‐/mesoporous solid‐solution network not only contains numerous macropores, but also possesses an interior mesoporous structure. The mesopore size and BET surface area of the network have been measured as 2–25 nm and 140.5 m2 g?1, respectively. The hierarchical macro‐/mesoporous solid‐solution network with open and accessible pores was found to be well‐preserved after calcination at 800 °C, indicating especially high thermal stability. Due to its high specific surface area, the synergistic effect of the coupling of macropores and mesopores, and its high crystallinity, the Ce0.49Zr0.37Bi0.14O1.93 solid‐solution material shows a strong structure‐induced enhancement of visible‐light harvest and exhibits significantly improved visible‐light photocatalytic activity in the photodegradation of methyl orange compared with those of its other forms, such as mesoporous hollow spheres and bulk particles.  相似文献   

3.
An improvement in the photodegradation performance for dyes due to interaction between carbon and titania in a self‐assembled mesoporous C? TiO2 composite catalyst, even for the difficult degradation of azo dyes, is reported herein. The dye removal process involves adsorption of the dye from water by the mesoporous carbon–titania, followed by photodegradation on the separated dye‐loaded solid. Such adsorption–catalysis cycles can be carried out more than 80 times without discernible loss of photocatalytic activity or the anatase content of the composite. In each run, about 120 mg dye per g catalyst can be degraded. The mesoporous carbon–titania catalyst also exhibits a high capacity for converting methyl orange in aqueous solution under visible light. Characterization by XRD, TEM, and N2 sorption techniques has revealed that the self‐assembled composite catalyst has an ordered mesostructure, uniform mesopores (4.3 nm), a large pore volume (0.30 cm3 g?1), and a high surface area (348 m2 g?1). The pore walls are composed of amorphous carbon and anatase nanoparticles of size 4.2 nm, which are well dispersed and confined. X‐ray photoelectron spectroscopy (XPS), surface photovoltage spectroscopy (SPS), and UV/Vis absorption results indicate doping of carbon into the anatase lattice and a change in the bandgap of the semiconductor. The synergistic improvement in the composite catalyst can be attributed to the following features: (1) carbon doping of the anatase lattice modifies its bandgap and enhances its activity under visible light; (2) confinement within carbon pore walls prevents aggregation of tiny anatase nanoparticles, improving their activity and stability; (3) the mesopores provide a confined space for photocatalysis; and (4) the strong adsorption ability of porous carbon for organic substances ensures that large quantities can be processed and inhibits further diffusion of the adsorbed organic substances, thereby enhancing the mineralization on anatase.  相似文献   

4.
As a typical photocatalyst for CO2 reduction, practical applications of TiO2 still suffer from low photocatalytic efficiency and limited visible‐light absorption. Herein, a novel Au‐nanoparticle (NP)‐decorated ordered mesoporous TiO2 (OMT) composite (OMT‐Au) was successfully fabricated, in which Au NPs were uniformly dispersed on the OMT. Due to the surface plasmon resonance (SPR) effect derived from the excited Au NPs, the TiO2 shows high photocatalytic performance for CO2 reduction under visible light. The ordered mesoporous TiO2 exhibits superior material and structure, with a high surface area that offers more catalytically active sites. More importantly, the three‐dimensional transport channels ensure the smooth flow of gas molecules, highly efficient CO2 adsorption, and the fast and steady transmission of hot electrons excited from the Au NPs, which lead to a further improvement in the photocatalytic performance. These results highlight the possibility of improving the photocatalysis for CO2 reduction under visible light by constructing OMT‐based Au‐SPR‐induced photocatalysts.  相似文献   

5.
Nickel, nitrogen-codoped mesoporous TiO2 microspheres (Ni–N–TiO2) with high surface area, and an effective direct band gap energy of ∼2.58 eV. Nickel sulfate used as the Ni source and ammonia gas as the N source here. The efficiency of the as-prepared samples was investigated by monitoring the degradation of Rhodamine B under visible light irradiation. The experimental results indicate that Ni-doped mesoporous TiO2 microspheres show higher photocatalytic activity than mesoporous TiO2 microspheres under visible light irradiation. It mainly due to that the electron trap level (Ni2+/Ni+) promoting the separation of charge carriers and the oxygen vacancies inducing the visible light absorption. In addition, Ni–N–TiO2 shows enhanced activity compared with Ni–TiO2. Codopants and dopants are found to be uniformly distributed in TiO2 matrix. Among the all samples the 0.5% molar quantity of Ni dopant and 500 °C 2 h nitriding condition gives the highest photocatalytic activity. The treatment of ammonia gas on Ni–TiO2 sample induced oxygen vancancies, substitutional and interstitial N. A suitable treatment by ammonia gas also promote separation of charge carriers and the absorption of visible light. The active species generated in the photocatalytic system were also investigated. The strategy presented here gives a promising route towards the development of a metal and non-metal codoped semiconductor materials for applied photocatalysis and related applications.  相似文献   

6.
Porous ZnS and ZnO nano‐crystal films were fabricated via a three‐step procedure. First, Zn(CH3COO)2/Silk Fibroin nanofiber mats were prepared by coaxial electrospinning. Second, Zn(CH3COO)2/Silk Fibroin mats were immersed in NaS solution to react with S2− to obtain ZnS/Silk Fibroin nanofiber mats. Finally, ZnO porous films were prepared by calcination of ZnS/Silk Fibroin composite mat at 600°C in air atmosphere. When ZnS/Silk Fibroin mats were calcinated in nitrogen, ZnS/Carbon composite mats were obtained accordingly. The resulting porous films were fully characterized. The ZnO porous films were the aggregation of ZnO nano‐crystal with hexagonal wurtzite structure. The seize of ZnO was estimated in the range of 10–20 nm. Both of the ZnS and ZnO nano‐crystal films exhibited high photocatalytic activities for the photodegradation of Methylene blue and Rhodamine B. It was also found that ZnO porous films are better than ZnS/Carbon nanofiber mats. In addition, photocatalysis of a real wastewater sample from a printing and dyeing company was conducted. The ZnO porous films exhibited excellent performance to treat the real samples. Moreover, the porous ZnO nano‐crystal photocatalyst could easily be recycled without notable loss of catalysis ability.  相似文献   

7.
The mesoporous titanium dioxide (MTiO2) photocatalysts co‐doped with Fe and H3PW12O40 were synthesized by template method using tetrabutyl titanate (Ti(OC4H9)4), Fe(NO3)k39H2Oand H3PW12O40 as precursors and Pluronic P123 as template. The as‐prepared photocatalyst was characterized by N2 adsorption‐desorption measurements, X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐vis adsorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl blue (MB) (50 mg/L) in an aqueous solution. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m2/g. The results of MB photodecomposition showed that co‐doped mesoporous TiO2 exhibited higher photocatalytic activities than un‐doped, single‐doped mesoporous TiO2 under UV and visible light irradiation. It was shown that the co‐doped MTiO2 could be activated by visible light and could thus be used as an effective catalyst in photo‐oxidation reactions. The synergistic effect of Fe and H3PW12O40 co‐doping played an important role in improving the photocatalytic activity.  相似文献   

8.
In a tannic acid assisted synthesis of mesoporous TiO2, tannic acid was used as a cost effective and non‐toxic template for pore formation. Meanwhile, a gold nanoparticles (Au NPs) deposited TiO2 nanocomposite was coated on an indium tin oxide electrode for the fabrication of a photoelectrochemical (PEC) biosensing system. Upon the formation of anatase structure, the electrode was coated with MoS2 for effective visible light absorption. The mesoporous structure led to an enhanced surface area by improving Au NPs and glucose oxidase adsorption. Incorporation of Au NPs led to an enhanced photonic efficiency due to the generation of Schottky barriers. The obtained nanocomposite was used for the light‐driven, real‐time, and selective PEC glucose sensing. Under visible light irradiation, the enzyme immobilized electrodes yielded significant photocurrent improvement owing to the releasing electron donor H2O2. The obtained PEC biosensor demonstrated acceptable reproducibility and stability with a sensitivity of 4.42 μA mM?1 cm?2 and a low detection limit of 1.2 μM glucose. Also, the linear measurement range was found to be 0.004–1.75 mM glucose. The results indicated that the proposed production method of mesoporous TiO2 will pave the way for a green chemistry based porous material production, along with the extension of the implementation of semiconductors in PEC biosensing systems.  相似文献   

9.
Fe3+ doped mesoporous TiO2 with ordered mesoporous structure were successfully prepared by the solvent evaporation-induced self-assembly process using P123 as soft template. The properties and structure of Fe3+ doped mesoporous TiO2 were characterized by means of XRD, EPR, BET, TEM, and UV–vis absorption spectra. The characteristic results clearly show that the amount of Fe3+ dopant affects the mesoporous structure as well as the visible light absorption of the catalysts. The photocatalytic activity of the prepared mesoporous TiO2 was evaluated from an analysis of the photodegradation of methyl orange under visible light irradiation. The results indicate that the sample of 0.50%Fe–MTiO2 exhibits the highest visible light photocatalytic activity compared with other catalysts.  相似文献   

10.
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/TiO2 and Pd/TiO2 heterostructured nanobelts by means of a simple co‐precipitation method, followed by a reduction process using surface‐modified TiO2 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 TiO2 nanobelts, respectively. Compared with TiO2 nanobelts, PdO/TiO2 and Pd/TiO2 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   

11.
以钛酸丁酯为前驱体, 碘溶胶为碘源, 在室温下采用水解沉淀法制备了单质碘和纳米TiO2复合的双介孔结构光催化剂(M-I2-TiO2). 采用X射线衍射(XRD)、透射电子显微镜(TEM)、比表面分析(BET)、紫外-可见(UV-Vis)漫反射光谱和傅里叶变换-红外光谱(FT-IR)对M-I2-TiO2进行了表征. 以次甲基蓝(MB)溶液为模拟废水, 对M-I2-TiO2的光催化性能进行了评价, 研究了不同热处理温度对光催化活性的影响. 结果表明, M-I2-TiO2在可见光区有显著的吸收, 300 ℃热处理得到的样品比表面积高达227.6 m2/g, 600 ℃热处理所得样品的比表面积仍高达111.8 m2/g, 而400 ℃热处理所得样品具有最好的光催化降解性能. 双介孔结构纳米TiO2/I2复合材料的光催化降解性能显著高于相同方法制备的纯TiO2和Degussa P-25商业产品. 催化剂经6次重复使用其光催化活性基本保持不变.  相似文献   

12.
考察了Pt促进的N掺杂TiO2(Pt/N-TiO2)催化剂对光催化降解有机污染物性能的影响及其作用本质.采用X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射光谱、光电化学和荧光光谱等手段对催化剂进行了表征,并考察了样品在可见光下光催化降解甲基橙(MO)的反应性能.结果表明,Pt的存在并未明显改变N-TiO2的晶...  相似文献   

13.
Nd3+ doped mesoporous TiO2 samples with different molar ratio of Nd/Ti were synthesized by a sol?Cgel method. The textural and optical properties of the samples were systematical characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption?Cdesorption isotherms, Fourier transform infrared spectroscopy and UV?CVisible absorbance spectroscopy. It was revealed that Nd3+ doping inhibited the phase transformation from anatase to rutile after calcination, and the mesoporous structure of doped samples was still retained with the increase of Nd/Ti molar ratio. The surface area of the samples varied from 137 to 210 m2g?1 and the average pore size of them ranged between 5.7 and 8.2?nm. The photocatalytic activities of all the samples were evaluated by degradation methyl orange (MO) in aqueous solution as a model reaction under UV light irradiation. The results showed that the doped samples demonstrated a higher photocatalytic activity than the mesoporous TiO2, and the 3?mol% Nd3+ doped mesoporous TiO2 exhibited the best photocatalytic performance. Meanwhile, a promotion effect of the H2O2 added was verified in the degradation of MO.  相似文献   

14.
A novel and facile method was developed to prepare a visible‐light driven TiO2/Ag‐AgCl@polypyrrole (PPy) photocatalyst with Ag‐AgCl nanoparticles supported on TiO2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag‐AgCl nanoparticles were prepared simultaneously onto TiO2 nanofibers, which simplified the preparation procedure. In addition, because Ag‐AgCl aggregates were fabricated via partly etching the Ag nanoparticles, their size was well controlled at the nanoscale, which was beneficial for improvement of the contact surface area. Compared with reference photocatalysts, the TiO2/Ag‐AgCl@PPy composite exhibited an enhanced photodegradation activity towards rhodamine B under visible‐light irradiation. The superior photocatalytic property originated from synergistic effects between TiO2 nanofibers, Ag‐AgCl nanoparticles and the PPy shell. Furthermore, the TiO2/Ag‐AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity.  相似文献   

15.
A magnetized nano‐photocatalyst based on TiO2/magnetic graphene was developed for efficient photodegradation of crystal violet (CV). Scanning electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and elemental mapping were used to characterize the prepared magnetic nano‐photocatalyst. The photocatalytic activity of the synthesized magnetic nano‐photocatalyst was evaluated using the decomposition of CV as a model organic pollutant under UV light irradiation. The obtained results showed that TiO2/magnetic graphene exhibited much higher photocatalytic performance than bare TiO2. Incorporation of graphene enhanced the activity of the prepared magnetic nano‐photocatalyst. TiO2/magnetic graphene can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, magnetized nano‐photocatalyst dosage, UV light irradiation time, H2O2 amount and initial concentration of dye on the photodegradation efficiency were evaluated and optimized. Efficient photodegradation (>98%) of the selected dye under optimized conditions using the synthesized nano‐photocatalyst under UV light irradiation was achieved in 25 min. The prepared magnetic nano‐photocatalyst can be used in a wide pH range (4–10) for degradation of CV. The effects of scavengers, namely methanol (OH? scavenger), p‐benzoquinone (O2?? scavenger) and disodium ethylenediaminetetraacetate (hole scavenger), on CV photodegradation were investigated.  相似文献   

16.
Visible‐light‐driven plasmonic photocatalyst Ag‐TiO2 nanocomposite hollow spheres are prepared by a template‐free chemically‐induced self‐transformation strategy under microwave‐hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, N2 adsorption‐desorption isotherms, X‐ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of ?OH radicals on the surface of visible‐light illuminated TiO2 was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as‐prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible‐light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO2 hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO2 nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible‐light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO2 and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO2 nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium ( R ) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2.  相似文献   

17.
Lanthanum doped mesoporous titanium dioxide photocatalysts with different La content were synthesized by template method using tetrabutyltitanate (Ti(OC4H9)4) as precursor and Pluronic P123 as template. The catalysts were characterized by thermogravimetric dif-ferential thermal analysis, N2 adsorption-desorption measurements, X-ray diffraction, and UV-Vis adsorption spectroscopy. The effect of La3+ doping concentration from 0.1% to 1% on the photocatalytic activity of mesoporous TiO2 was investigated. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of about 10 nm with high surface area of 165 m2/g. X-ray photoelectron spectroscopy measurements in-dicated the presence of C in the doped samples in addition to La. Compared with pure mesoporous TiO2, the La-doped samples extended the photoabsorption edge into the visible light region. The results of phenol photodecomposition showed that La-doped mesoporous TiO2 exhibited higher photocatalytic activities than pure mesoporous TiO2 under UV and visible light irradiation.  相似文献   

18.
Mesoporous RuO2–TiO2 nanocomposites at different RuO2 concentrations (0–10 wt %) are prepared through a simple one‐step sol–gel reaction of tetrabutyl orthotitanate with ruthenium(III) acetylacetonate in the presence of an F127 triblock copolymer as structure‐directing agent. The thus‐formed RuO2–TiO2 network gels are calcined at 450 °C for 4 h leading to mesoporous RuO2–TiO2 nanocomposites. The photocatalytic CH3OH oxidation to HCHO is chosen as the test reaction to examine the photocatalytic activity of the mesoporous RuO2–TiO2 nanocomposites under UV and visible light. The photooxidation of CH3OH is substantially affected by the loading amount and the degree of dispersion of RuO2 particles onto the TiO2, which indicates the exclusive effect of the RuO2 nanoparticles on this photocatalytic reaction under visible light. The measured photonic efficiency ξ=0.53 % of 0.5 wt % RuO2–TiO2 nanocomposite for CH3OH oxidation is maximal and the further increase of RuO2 loading up to 10 wt % gradually decreases this value. The cause of the visible‐light photocatalytic behavior is the incorporation of small amounts of Ru4+ into the anatase lattice. On the other hand, under UV light, undoped TiO2 shows a very good photonic efficiency, which is more than three times that for commercial photocatalyst, P‐25 (Evonik–Degussa); however, addition of RuO2 suppresses the photonic efficiency of TiO2. The proposed reaction mechanism based on the observed behavior of RuO2–TiO2 photocatalysts under UV and visible light is explored.  相似文献   

19.
Composite nano‐TiO2 with doping Fe3+ and Ag was prepared, and further modified by 3‐methacryloxypropyltrimethoxysilane. They were characterized by Zetasizer Nano ZS Particle and Zeta Potential Analyzer, X‐ray diffraction, UV–Vis spectrophotometer, FT–IR spectra, and transmission electron microscopy. The modified composite nano‐TiO2 was applied to prepare multifunctional fluorocarbon coatings (FCC). Antibacterial activity of multifunctional FCC containing modified composite nano‐TiO2 was investigated. Its photocatalytic antibacterial activity reached 92%. The influence of doping ingredients, amount of composite nano‐TiO2, different light houses, or surface modification was discussed. The surface of FCC cannot be easily smirched by oiliness, dust or water because of hydrophobic fluorosilicone emulsion. It would be an available modern interior building coating for its remarkable photocatalytic antibacterial property as well as self‐cleaning function. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

20.
In this work, the photocatalytic activity of the synthesized graphene oxide (GO)‐Fe3O4/TiO2 mesoporous photocatalysts was evaluated using chlorpyrifos (CP) as a contaminant. The nano‐photocatalyst was characterized by X‐ray diffraction, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, and specific surface area by the Brunauer–Emmett–Teller method. Using visible light, the GO‐Fe3O4/TiO2 mesoporous photocatalyst was investigated on the degradation of CP pesticide. The GO‐Fe3O4/TiO2 photocatalyst displayed a good photocatalytic activity, which was achieving 97% of CP degradation after 60 min. Finally, experiments were performed to evaluate GO‐Fe3O4/TiO2 mesoporous nanocatalyst activity on repeated applications; after several uses, its photocatalytic activity was retained, which indicated stability.  相似文献   

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