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1.
以TiCl 4 、Fe (NO 3 ) 3·9H 2O 和Na 2SiO 319H 2O 为原料, 采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO 2/ Fe 2O 3 和TiO 2/ Fe 2O 3/ SiO 2 复合光催化剂。以光催化降解苯酚对所得催化剂的催化活性进行了评价。结果表明, 纳米TiO 2/ Fe 2O 3 复合粒子与单组分TiO 2 比较, 复合粒子光催化活性高于单组分的TiO 2, 6h 苯酚降解率高达95.9 %。SiO 2 的加入可以抑制纳米粒子粒径的长大和晶相的转变, 增强TiO 2 纳米粒子的热稳定性。复合光催化剂中Fe 2O 3 最佳掺入量为0.06 %, SiO 2 最佳掺入量为10 %(摩尔分数) 。并用XRD、TEM 和FTIR 等手段进行了表征。TiO 2 以锐钛矿型形式存在, SiO 2 以无定性形式存在。比较了不同制备方法制得的TiO 2/ Fe 2O 3 复合光催化剂, 得出超临界干燥法制备的光催化剂具有粒径小、比表面积大、分散性好、光催化活性高等特点。采用超临界流体干燥可直接得锐钛型纳米复合光催化剂。 相似文献
2.
较差的光催化产氢效率极大地阻碍了TiO 2光催化剂的工业化应用。为此,本文在含有NH 4VO 3的磷酸盐溶液中,采用等离子体电解氧化(PEO)法制备了多孔TiO 2/V 2O 5复合膜光催化剂,通过扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)、X射线光电子谱(XPS)和紫外可见漫反射光谱(UV-Vis DRS)对其组成、结构及光吸收性质进行了表征,并采用气相色谱评价了薄膜催化剂的光催化产氢性能,研究了电解液中NH 4VO 3含量对膜的结构、组成和光催化产氢性能的影响。结果表明:复合膜催化剂主要由锐钛矿和金红石型TiO 2组成,具有微孔结构,V 2O 5主要以无定形形式存在于膜中,与TiO 2有很强的相互作用,影响TiO 2的晶面间距。研究发现,元素V抑制了TiO 2的结晶和金红石型TiO 2的形成,扩大了薄膜的光学吸收范围。针对Na 2S+ Na 2SO 3溶液中的光催化产氢性能的研究显示,在质量浓度为1 g/L NH 4VO 3的电解液中制备的TiO 2/V 2O 5薄膜的光催化活性最高,优于近年来报道的其他光催化剂。光催化重复实验表明,该复合膜催化剂具有较高的稳定性和较为恒定的光催化活性。 相似文献
3.
光催化降解室内挥发性有机物(VOCs)是TiO 2光催化材料应用的新领域。在介绍TiO 2光催化材料降解室内VOCs及改性机理的基础上,重点综述了催化降解室内VOCs用改性TiO 2光催化材料的离子掺杂、半导体复合、贵金属沉积等改性制备的研究新进展,并详细阐明了所制备的改性TiO 2光催化材料催化降解室内VOCs的研究现状,进而提出了改性TiO 2光催化材料降解室内VOCs需进一步深入展开的研究工作。 相似文献
4.
采用水热法,通过改变水热温度成功制备出一系列一维TiO 2纳米管、纳米线和纳米带。运用X射线衍射、透射电子显微镜、N 2吸附-脱附和紫外-可见光谱等手段表征了材料的结构和性质,并考察了一维TiO 2样品光催化降解气相苯的活性。结果表明,一维TiO 2纳米材料具有较高的比表面积,光吸收出现明显的“蓝移”,光催化活性较P25有所提高,其中140 ℃水热温度下制备出的TiO 2纳米管的光催化活性最佳,80 min内对气相苯的去除率为77%,终产物CO 2的浓度为625 mg/m 3。 相似文献
5.
锐钛矿相的TiO 2晶体主要由热力学稳定的(101)晶面组成,而具有较高活性的(001)晶面所占比例较少。通过F离子的引入,当其吸附在TiO 2的高活性(001)晶面上时,可以使晶面的表面能降低,从而制备出暴露(001)晶面的TiO 2。为提高该TiO 2的气敏性能,通过水热法将纳米TiO 2与SiC超细纤维复合,制备出具有分级结构的TiO 2/SiC复合纤维,以此解决TiO 2回收难及单晶TiO 2之间团聚的问题。结果表明,对于丙酮气体,所合成的TiO 2/SiC复合纤维的灵敏度(21.2)是暴露(001)晶面的纳米TiO 2灵敏度(14.0)的1.5倍,是商业TiO 2灵敏度(4.0)的5.3倍。 相似文献
6.
TiO 2-SiO 2复合材料(TSCM)的催化应用性能受到其所含TiO 2物种的晶相和SiO 2骨架的孔道结构的显著影响。本文归纳总结了TSCM中TiO 2物种晶相、SiO 2骨架的孔道结构、形貌等特性的调变规律及其对TSCM催化性能的影响,并展望了TSCM材料的结构特性演变趋势以及在制备方法上的取舍。TSCM直接作为催化剂时,其活性位普遍被认为是TiO 2-SiO 2界面上的Ti—O—Si键位和酸性位点。而作为载体材料时,TSCM中的TiO 2物种可以与负载的金属活性中心表现出显著的载体-金属相互作用(SMSI),TiO 2物种的晶相可以对形成的金属活性中心的性能产生显著影响。在TSCM材料的合成研究中,合成含有单一锐钛矿相(Anatase)TiO 2物种的Anatase-SiO 2或单一金红石晶相(Rutile)的Rutile-SiO 2类型TSCM材料,以及同时含有这两个晶相TiO 2,但晶相比例可调的A/R-SiO 2类型TSCM材料仍充满挑战。TSCM的SiO 2骨架特性调控也同样具有挑战,如何在得到特定晶相和粒子尺寸的TiO 2物种的同时获得特定孔道特性和形貌特征的SiO 2骨架,仍是研究的难点和热点。两步法无需同时控制TiO 2和SiO 2物种的制备参数,重现性好,多用于特殊形貌的TSCM的制备,但通常其中TiO 2物种的分散度不佳。而一步法制备过程简短,更容易得到多孔-大比表面积材料,有利于实现TiO 2粒子的尺寸控制及其在SiO 2骨架中的均匀分布,从而得到更丰富的Ti—O—Si界面活性物种,但需要在同一合成体系中同时控制相互影响的TiO 2和SiO 2物种的制备参数,调控难度极大,与两步法相比,重现性较差。 相似文献
7.
基于一种新型的纳米二氧化钛(TiO 2)粉体,利用熔体共混方式制备了纳米TiO 2/聚丙烯(PP)复合材料,研究了复合材料的相分散结构、结晶特性、力学性能、杀菌性能和流动性能。结果发现:新型纳米TiO 2在聚丙烯中有较好的分散度,绝大多数纳米TiO 2在聚丙烯中的聚集体尺寸接近于100纳米;新型纳米TiO 2对聚丙烯有一定的结晶成核作用,但并不能提高结晶度;复合材料的力学性能随纳米TiO 2含量的增加呈现出拉伸强度下降,伸长率降低,模量和冲击强度上升的趋势。2%纳米TiO 2含量的聚丙烯复合材料的综合物理机械性能较好。新型纳米TiO 2填充到PP中可以起到良好的抗菌杀菌作用,但也在一定程度上使聚丙烯发生氧化降解,进而导致纳米TiO 2/聚丙烯复合材料的流动性略优于纯聚丙烯。 相似文献
8.
采用常规的陶瓷工艺制备了BaWO 4/(Ba,Sr)TiO 3复合陶瓷,并通过X射线衍射、扫描电镜及介电性能测试对陶瓷的烧结特性、微结构和介电性能进行了研究。结果表明,BaWO 4/(Ba,Sr)TiO 3复合陶瓷在1250~1300℃ 可以实现致密化烧结,且陶瓷由(Ba,Sr)TiO 3和BaWO 4两相复合而成,未检测到其它物相。随着BaWO 4含量的增加,材料的表观密度逐渐增大,介电常数和可调度逐渐降低,介电损耗变化不大,均在10-3量级。典型样品(60 %BaWO 4/40%Ba 0.5Sr 0.5TiO 3 , 质量分数)介电常数182.7,介电损耗0.0024,在2V·μm-1偏置电场下的可调度为14.7%,具有较好的介电性能。 相似文献
9.
采用电场激活压力辅助合成技术(FAPAS)制备了(TiB 2) PNi/(TiB 2) PNi 3Al/Ni 3Al/Ni梯度材料,主要研究电场激活燃烧合成过程中电场对材料合成及层界面扩散连接的作用。分析了梯度材料各层的界面微观组织及相组成和材料的硬度分布。结果表明,采用FAPAS 技术结合机械合金化工艺制备的(TiB 2) PNi/(TiB 2) PNi 3Al/Ni 3Al/Ni 功能梯度材料具有快速、简便和组织均匀密实的特点。梯度材料的陶瓷复合层、Ni 3Al层和Ni板的界面区产生成分的互扩散,形成了良好的冶金结合。从Ni板到陶瓷复合层的硬度呈梯度分布。 相似文献
10.
Ag作为助催化剂能够促进光电子的迁移,在光催化分解水制氢气、CO 2还原、重金属离子还原等反应中应用颇多,然而,到目前为止未见将Ag单质作为助催化剂用于光催化固氮产氨反应的报道。本工作制备了负载单质Ag的g-C 3N 4(Ⅰ)/g-C 3N 4(Ⅱ)同素异质结催化剂,并考察了其光催化固氮产氨的性能。采用X射线衍射(XRD)、透射电镜(TEM)、紫外可见光谱(UV-Vis)、X射线光电子能谱(XPS)、拉曼光谱(Raman)、荧光光谱(PL)、电化学阻抗谱(EIS)、光电流分析等手段对制备的催化剂进行了表征。结果表明,Ag以单质态存在于催化剂表面。所担载的Ag的等离子体效应一方面促进了催化剂对可见光的吸收,使反应体系能产生更多的光生电子-空穴对;另一方面使得光生电子能够在g-C 3N 4与Ag单质间迁移,提高了催化剂的电子-空穴分离效率。负载Ag后g-C 3N 4(Ⅰ)/g-C 3N 4(Ⅱ)同素异质结催化剂的铵离子产生速率为1.36 mg·L-1·h-1·g-1 cat,相比未负载Ag时(0.59 mg·L-1·h-1·g-1 cat)大幅提高,与Pt负载催化剂相当,并且是由单纯三聚氰胺和尿素制备的g-C 3N 4的4.9倍和3.4倍。除固氮反应外,制备的载银g-C 3N 4(Ⅰ)/g-C 3N 4(Ⅱ)同素异质结催化剂在光催化还原氧气制取双氧水的反应中也表现出优良的催化性能。 相似文献
11.
Titanium dioxide is one of the best semiconductor photocatalysts available for photocatalytic reaction of dye pollutants.
To prevent the recombination caused by the relatively low photocatalytic efficiency, Ag doped TiO 2 nanofiber was prepared by electrospinning method. The photocatalysts (pure TiO 2 nanofiber and Ag doped TiO 2 nanofiber) were characterized by FE-SEM, XRD, XPS, and PL analysis. These photocatalysts were evaluated by the photodecomposition
of methylene blue under UV light. Ag doped TiO 2 nanofiber was found to be more efficient than pure TiO 2 fiber for photocatalytic degradation of methylene blue. The photocatalytic degradation rate was applied to pseudo-first-order
equation. The degradation of Ag doped TiO 2 nanofiber was significantly higher than the degradation rate of pure TiO 2 nanofiber. Activation energy was calculated by applying Arrhenius equation from the rate constant of photocatalytic reaction.
The activation energies for the pure TiO 2 nanofibers calcined at 400 and 500 °C were 16.981 and 12.187 kJ/mol and those of Ag doped TiO 2 nanofibers were 18.317 and 7.977 kJ/mol, respectively. 相似文献
12.
Titanium dioxide (TiO 2) powder-containing sheet composites, called TiO 2 sheet, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO 2 powders were homogeneously scattered over the fiber-mix networks tailored within the catalyst sheet. Under UV irradiation,
the TiO 2 paper could decompose p-hydroxyacetophenone ( p-HAP), although the degradation efficiency by the TiO 2 sheet was lower than that by the TiO 2 powder. Scanning electron microscopy revealed that coverage of the TiO 2 particles inside the sheet by alumina binder which was used to improve the sheet strength caused the deterioration of the
photocatalytic performance. Internal addition of alumina binder made the TiO 2 sheet porous and such a TiO 2 sheet exhibited high photocatalytic performance equivalent to that of TiO 2 powder. The porous structure of TiO 2 sheet might contribute to effective transport of p-HAP to the surface of TiO 2 particles inside the sheet, resulting in high degradation performance. In addition, TiO 2 sheet prepared using TiO 2 sol showed higher photocatalytic efficiency than TiO 2 powder and it was indicated that the porous sheet structure might provide suitable conditions for TiO 2 catalysis for photodecomposition. 相似文献
13.
The TiO 2 supported on tourmaline composite catalyst was successfully prepared by a sol–gel method and was characterized by scanning electron microscopy, X-ray diffraction and nitrogen adsorption–desorption analysis. The results showed that the addition of tourmaline increased crystallite sizes of TiO 2. Furthermore, the photocatalytic activity of the tourmaline–TiO 2 composites obtained was evaluated by the degradation of tetrabromobisphenol A (TBBPA). Compared with bare TiO 2, the tourmaline–TiO 2 composites exhibited the excellent photocatalytic activity for the degradation of TBBPA and this degradation enhanced was correlated with the tourmaline dosages and the optimum photocatalyst is found to be T(20%)-TiO 2 catalyst. It implied that the higher dosage of tourmaline facilitated migration of charge carriers and higher photon-to-electron conversion efficiency. The photocatalytic reaction followed pseudo-first-order kinetics and the Langmuir–Hinshelwood model. The photodegradation efficiency of TBBPA enhanced with the increase in pH value. Additionally, metal ions influenced the photocatalytic degradation of TBBPA by T(20%)-TiO 2 catalyst, Cu 2+ could accelerate TBBPA degradation, whereas inhibited by Mn 2+ and Fe 3+. Importantly, five intermediate products of TBBPA at m/ z 463, 355, 293, 255 and 137 were observed by HPLC–MS/MS. The possible photodegradation pathway of TBBPA by tourmaline–TiO 2 composite catalyst was proposed. Generally, the incorporation of mineral with spontaneous permanent poles to TiO 2 with photocatalytic activity offers a promising technology to the practical application of TiO 2 in contamination control. 相似文献
14.
Fe 3+ doped TiO 2 composite nanofiber membranes and pure TiO 2 nanofiber membranes were prepared through electrospinning, and were applied to the photocatalytic degradation of malachite green (MG) in aqueous solutions under simulated sunlight. The effects of ferric ion content, initial concentration of MG, photocatalyst loading, and recycling behavior were studied. Microscopic characterization showed that the products have fiber morphology with bent property and favorable continuity. The degradation results showed that TiO 2 nanofiber membranes containing 0.8 mol% Fe 3+ performed the best photocatalytic activity against MG under identical light irradiation. The TiO 2:Fe 3+ composite nanofiber membranes maintained their photocatalytic efficiency through seven recycling processes. 相似文献
15.
In the present work the nanostructured carbon-doped TiO 2 thin films with nanorod morphology were deposited on glass substrate by a combination of ultrasonic and chemical vapor deposition methods, and for the first time were applied for the photocatalytic degradation of paraoxon and parathion organophosphorus pesticides under visible light irradiation. X-ray Diffraction, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, and scanning electron microscopy techniques were used for characterization of the prepared thin films. Obtained results show that presence of carbon element and also special nanorod morphology of the thin films remarkably improve the optical properties of TiO 2 in visible light region and results in the good visible light photocatalytic activity of the thin films for degradation of the pesticides. The photonic efficiencies of the prepared thin films were also examined based on the international ISO-10678:2010 standard protocol for photocatalytic degradation of methylene blue under UV light irradiation. The results show a maximum photonic efficiency of 0.0312% for the carbon-doped TiO 2 thin film with 570 nm thickness, which compared to a reference standard TiO 2 films indicates a 30% improvement in photonic efficiency. 相似文献
16.
The TiO 2/Eggshell, TiO 2/Clamshell and TiO 2/CaCO 3 loaded composites were prepared by sol-gel method and characterized by XRD and SEM. Their photocatalytic activities were measured through the degradation of Acid Red B under solar light irradiation. The influences of TiO 2 loaded content, heat-treated temperature and time on the photocatalytic activities were reviewed. The effects of irradiation time and dye initial concentration on the photocatalytic degradation were also investigated. The results showed that the photocatalytic activity can be greatly enhanced by appropriate TiO 2 loaded content. 相似文献
17.
A series of polypyrrole (PPy)/titanium dioxide (TiO 2) nanocomposites were prepared in different polymerization conditions by ‘in situ’ chemical oxidative polymerization. The
nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), X-ray
photoelectron spectroscopy spectra (XPS), and UV–Vis diffuse reflectance spectra. The photocatalytic degradation of methyl
orange (MO) was chosen as a model reaction to evaluate the photocatalytic activities of TiO 2/PPy catalysts. The results show that a strong interaction exists at the interface between TiO 2 and PPy, the deposition of PPy on TiO 2 nanoparticles can alleviate their agglomeration, PPy/TiO 2 nanocomposites show stronger absorbance than neat TiO 2 under the whole range of visible light. The obtained PPy/TiO 2 nanocomposites exhibit significantly higher photocatalytic activity than the neat TiO 2 on the degradation of MO aqueous solution under visible and UV light illumination. The reasons for improving the photocatalytic
activity were also discussed. 相似文献
18.
The photocatalytic degradation of indigo carmine dye was studied using hydrothermally prepared TiO 2 impregnated activated carbon (TiO 2: AC). A comparison between the degradation of the indigo carmine dye using commercial TiO 2 and TiO 2: AC revealed the efficiency of the title compound. The degradation reaction was optimized with respect to the dye concentration
and catalyst amount. The reduction in the chemical oxygen demand (COD) revealed the mineralization of dye along with colour
removal. The active compound like TiO 2 was impregnated onto the activated carbon surface under mild hydrothermal conditions (<250°C, P ∼ 40 bars). The impregnated
activated carbon samples were characterized using powder X-ray diffraction (XRD) and scanning electron microscope (SEM). 相似文献
19.
Herein, titanium dioxide (TiO2)-coated vertically aligned silicon nanowires (SiNWs/TiO2) were fabricated and evaluated for photocatalytic degradation of organic dyes. Aligned SiNWs arrays were prepared by facile metal-assisted chemical-etching process with varying the etching time that was followed by TiO2 nanoparticles coating using sputtering technique. The TiO2 film crystallized in pure anatase phase with an average crystalline size of 50 nm, as was elucidated with X-ray diffraction studies. SEM analysis showed nanowires with varying lengths from 2.5 to 13.5 µm and confirmed the homogenous surface decoration with TiO2. The homogeneous distribution of TiO2 nanoparticles on nanowires was co-evidenced with Energy-Dispersive X-ray spectroscopy (EDX) and Raman spectra analysis. The developed SiNWs/TiO2 was exploited for photocatalytic degradation of methylene blue; the role of hydrogen peroxide was also elucidated. The highest photocatalytic efficiency of 96% was achieved for SiNWs/TiO2 with optimum nanowire length of 3.5 μm. The developed photocatalyst was found to be almost stable even after 190 days (~?5 months) and could be used as reusable and easily removable photocatalysts. The current study highlighted the SiNWs/TiO2/H2O2 system as excellent candidate for water remediation applications. 相似文献
20.
The pH-sensitive photocatalytic system was prepared by embedding TiO 2 into poly(vinyl alcohol)/poly(acrylic acid) hydrogel. Two different type TiO 2/hydrogel composites, such as matrix and nanofiber, were prepared to investigate the morphological effects on the photocatalytic activity. TiO 2 was distributed uniformly in the composite hydrogel and kept the original anatase structure without any structural change. The photocatalytic activity of TiO 2 was evaluated based on the efficiency of photobleaching of dye. The photobleaching of dye was improved greatly as the pH was changed into basic condition and the larger surface area of hydrogel was available for TiO 2 by using nanofiber supports. 相似文献
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