钛酸四丁酯水解制备聚苯乙烯/二氧化钛核壳粒子及空心二氧化钛微球

通过无皂乳液聚合方法制备了阳离子型及阴离子型聚苯乙烯(PSt)乳胶粒,并对后者用γ-氨丙基三乙氧基硅烷(KH550)进行了表面改性制得了乳胶粒表面载正电荷的乳液.在乙醇与水的混合溶剂中,分别使用以上3种PSt乳胶粒为核加入钛酸四丁酯制备了核壳型PSt/TiO2复合粒子.结果显示,仅在使用经KH550改性的阴离子PSt乳...     

低温下溶胶凝胶法制备TiO2纳米晶

从含过量水的溶胶出发,在室温下得到了TiO₂纳米晶。通过红外光谱,透射电子显微镜法和X射线粉末衍射法对含有过量水的溶胶体系中TiO₂纳米晶的室温形成机理进行了研究。与传统的溶胶凝胶法相比,在改良的溶胶凝胶体系中,在缩聚反应之前由于水过量使得钛的先驱体快速且充分的水解,从而生成[TiO₆]基团,随之形成TiO₂纳米晶。晶粒的尺寸为约3.5 nm,该法得到的TiO₂纳米晶比传统溶胶凝胶法得到的TiO₂纳米晶和商用光催化剂德固赛P25具有更好的光催化活性。     

Nano sulfated titania as solid acid catalyst in direct synthesis of fatty acid amides

Nanosized sulfated titania was prepared by a sol-gel hydrothermal process. X-ray diffraction (XRD), transmission electron, and scanning electron micrographs (TEM and SEM), FT-IR specific surface area, and BET N(2) adsorption were employed to characterize the properties of the synthesized sulfated TiO(2). The results indicate that both anatase and rutile TiO(2) are obtainable. This prepared sulfated titania showed high catalytic activity in direct amidation of fatty acids as well as benzoic acids with various amines under solvent-free conditions.     

Cu掺杂TiO2及其纳米管的制备、表征与光催化性能

通过溶胶-凝胶法和水热法制备了Cu掺杂TiO₂纳米粉末及其纳米管,并通过XRD、TEM、FE-SEM、EDS、UV-Vis/DRS等手段分析了样品的结构。发现以Cu掺杂TiO₂纳米粉末为水热反应原料制备的纳米管中不含Cu,对其原因进行了分析讨论并通过Zn掺杂TiO₂纳米粉末证实：以金属掺杂TiO₂纳米粉末为原料,通过水热法制备TiO₂纳米管中不含有相应金属离子,这是由于金属离子在强碱水热条件下形成金属配离子,使金属离子溶解于水中而不能形成金属掺杂TiO₂纳米管。对所得样品进行了光催化性能测试,发现：Cu掺杂TiO₂粉末的光催化产氢效率为0.75 μmol·(g·h)^-1,高于由其本身及P25通过水热法制备的TiO₂纳米管(分别为：0.42 μmol·(g·h)^-1,0.25 μmol·(g·h)^-1)的光催化产氢效率。     

Hydrothermal synthesis of single-crystalline anatase TiO2 nanorods with nanotubes as the precursor

Preparation of anatase TiO2 nanorods from solutions in the absence of surfactants or templates has rarely been reported. The present work has found that hydrothermal treatment of titanate nanotube suspensions under an acidic environment resulted in the formation of single-crystalline anatase nanorods with a specific crystal-elongation direction. The nanotube suspensions were prepared by treatment of TiO2 in NaOH, followed by mixing with HNO3 to different pH values. The crystal size of the anatase nanoparticles obtained from the hydrothermal treatment increased with the pH of the suspensions, and nanorods with an aspect ratio up to 6 and a long axis along the anatase [001] were obtained at a pH slightly less than 7. A mechanism for the tube-to-rod transformation has been proposed on the basis of the crystalline structures of the tubes and rods. The local shrinkage of the tube walls to form anatase crystallites and the subsequent oriented attachment of the crystallites have been suggested to be the key steps involved in the nanorod formation.     

Synthesis and photonic band calculations of NCP face-centered cubic photonic crystals of TiO2 hollow spheres

With the help of self-assembly, thermal sintering, selective etching techniques and sol-gel process, the non-close packed (ncp) face-centered cubic (fcc) photonic crystals of titanium dioxide (TiO2) hollow spheres connected by TiO2 cylindrical tubes have been fabricated using silica template. The photonic bandgap calculations indicate that the ncp structure of TiO2 hollow spheres was easier to open the pseudogaps than close packed system at the lowest energy.     

利用胶体碳球为模板制备SiO2、TiO2、SnO2空心球

介观尺度的氧化物空心球材料在许多领域都有着潜在的应用价值[1],因此近年来受到人们的广泛关注。其制备方法包括:模板法[2],声化学法[3],水热法[4]等。其中胶体粒子模板合成是制备氧化物空心球材料的一条最为有效的途径。常见的胶体粒子有金、银、CdS的纳米粒子,介观尺度的SiO     

Synthesis of tubular titanate via a self-assembly and self-removal process

Novel morphology titanate tubes were successfully synthesized via a self-assembly and self-removal process. After the product was treated by calcinating and washing, crystalline TiO2 tubes were obtained. In this study, two new concepts are applied to design the synthetic route: (i) titanium glycolate rods obtained from an ethylene glycol-mediated process and titanate sheets synthesized using the hydrothermal process were used as the template and the precursor, respectively, and ii) the template was directly removed in the reaction without posttreatment. Furthermore, a possible mechanism was proposed for the formation of tubular structures.     

Long TiO2 hollow fibers with mesoporous walls: sol-gel combined electrospun fabrication and photocatalytic properties

Long TiO2 hollow fibers with mesoporous walls have been fabricated with the sol-gel combined two-capillary spinneret electrospinning technique using a triblock copolymer (Pluronic, P123, (H(C2H5O)20(C3H7O)70 (C2H5O)20OH) as a pore-directing agent. The as-prepared hollow fibers were as long as 30 cm with an outer diameter of 0.1-4 microm and wall thickness of 60-500 nm. The diameters and wall thicknesses of the hollow fibers could be tuned by adjusting the electrospinning parameters. The fiber walls were composed of mesopores 6.7 nm in diameter as calculated from the N2 adsorption/desorption isotherm. The high-resolution TEM (HR-TEM) images exhibited that the mesopores were hexagonally aligned with a low order because of the curving of the pores. When comparing with other nanostructured TiO2 materials such as commercial TiO2 nanoparticles (P25, Degussa) and mesoporous TiO2 powders, the hollow fibers exhibited higher photocatalytic activities toward degradation of methylene blue and gaseous formaldehyde.     

Phase transition between nanostructures of titanate and titanium dioxides via simple wet-chemical reactions

Titanate nanofibers of various sizes and layered structure were prepared from inorganic titanium compounds by hydrothermal reactions. These fibers are different from "refractory" mineral substances because of their dimension, morphology, and significant large ratio of surface to volume, and, surprisingly, they are highly reactive. We found, for the first time, that phase transitions from the titanate nanostructures to TiO(2) polymorphs take place readily in simple wet-chemical processes at temperatures close to ambient temperature. In acidic aqueous dispersions, the fibers transform to anatase and rutile nanoparticles, respectively, but via different mechanisms. The titanate fibers prepared at lower hydrothermal temperatures transform to TiO(2) polymorphs at correspondingly lower temperatures because they are thinner, possess a larger surface area and more defects, and possess a less rigid crystal structure, resulting in lower stability. The transformations are reversible: in this case, the obtained TiO(2) nanocrystals reacted with concentrate NaOH solution, yielding hollow titanate nanotubes. Consequently, there are reversible transformation pathways for transitions between the titanates and the titanium dioxide polymorphs, via wet-chemical reactions at moderate temperatures. The significance of these findings arises because such transitions can be engineered to produce numerous delicate nanostructures under moderate conditions. To demonstrate the commercial application potential of these processes, we also report titanate and TiO(2) nanostructures synthesized directly from rutile minerals and industrial-grade rutiles by a new scheme of hydrometallurgical reactions.     

制备均一形貌的长二氧化钛纳米管

在温和的水热条件下,用碱溶液处理不同粒径的锐钛矿相和金红石相二氧化钛 纳米粉体,得到了不同形貌的二氧化钛纳米管,并用TEM,XRD,FT-Raman和BET等 对其进行了表征。金红石相的超细纳米晶有利于形成均一形貌的纳米管,用粒径仅 为7.2 nm的金红石相纳米粉体为前驱体得到了长度为500 nm的长二氧化钛纳米管。 用纳米晶反应活性对晶粒尺寸的依赖性及晶相稳定性解释了长纳米管的形成机理。     

Bamboo-shaped carbon tubes from coal

Bamboo-shaped carbon tubes (BCTs) were first synthesized in high yields from iron-loaded carbon electrodes prepared from coal by arc discharge. The BCTs were characterized by scanning electron microscopy and transmission electron microscopy (TEM). The TEM characterization reveals that the tubes have bamboo-like structures consisting of hollow compartments separated with conical shaped graphite layers. The diameters of BCTs are in the range of 40–60 nm with their length being about several micrometers. For some BCTs, the hollow compartments are quite uniform with a size of 100 nm. A growth model is suggested to explain the formation of bamboo structure in tubes.     

拓扑相变制备具有拓宽可见光响应范围的Ti3+自掺杂3D空盒状TiO2

TiO2广泛用作半导体光催化材料, 但由于自身对光利用率低(只吸收紫外光)、禁带宽度较大、光生载流子复合率极高, 限制了它在相关领域的应用. 为此, 设计了Ti3+离子自掺杂来克服TiO2半导体材料的上述缺点, 进而提高其光催化活性. 在不引入其他元素的情况下, 以TiOF2为原料, Zn粉为还原剂, 在水热条件下采用拓扑相变法原位制备了具有可见光响应的Ti3+自掺杂空盒状TiO2(记为Ti3+/TiO2)催化剂材料. 掺杂金属离子可以改变半导体TiO2的结晶度和产生晶格缺陷, 形成电子或空穴的捕获中心, 影响电子-空穴对的复合; 同时, 掺杂金属离子产生的晶格缺陷有利于Ti3+和氧空位的形成, 有利于提高TiO2的量子效率. Ti3+掺杂是一种既清洁又未引入其他金属离子的掺杂改性方法, 它能有效保持催化剂的结构和形貌不受其他金属离子的影响. 总之, 金属离子掺杂有效拓展了TiO2的光吸收范围, 并极大地提高了TiO2的光催化活性.本文研究了不同量的还原剂对催化剂空盒状TiO2结构形貌影响, 以及在可见光下光催化降解罗丹明B反应性能, 发现Ti3+/TiO2催化剂均拥有非常好的光催化活性, 其中R0.25催化剂在可见光下120 min, RhB降解率达到96%, 是TiO2的4倍多. 且可循环使用5次的光催化循环降解实验后, 表现出较高的稳定性. 催化剂经过Ti3+自掺杂后, 对催化剂自身的空盒状结构形貌并无很大的影响, 随着还原剂Zn粉的量增加, Ti4+还原形成Ti3+数量增加, 导致形成更多的氧空位. 皆为锐钛矿型TiO2,与未掺杂Ti3+的TiO2比较发现, 自掺杂Ti3+的TiO2的(105)XRD衍射峰越来越尖锐, (004)衍射峰越来越宽. 随着还原剂Zn粉质量的逐渐增加, 催化剂的光响应范围拓宽到可见光区, 且逐渐增强. 这说明Ti3+的掺杂不仅提高了TiO2在可见光的响应能力, 也提高了TiO2在紫外光范围的响应能力. 另外, 掺杂后的TiO2禁带宽度的减小, 使其价带上的电子更容易被可见光激发, 产生更多的电子-空穴对参与光催化反应, 从而提高TiO2的光催化效率.     

Hydrothermal synthesis, characterization, and photocatalytic performance of silica-modified titanium dioxide nanoparticles

Silica-modified titanium dioxides were prepared by a hydrothermal method and then characterized by XRD, FT-IR, XPS, TEM, and UV-visible spectroscopy. The silica-modified titanium dioxides were in anatase phase and had large surface areas. There was strong interaction between SiO2 and TiO2, and TiOSi bonds formed during the hydrothermal process. The addition of silica in TiO2 particles could effectively suppress the formation of the rutile phase and the growth of titanium dioxide crystals. DRS spectra proved an increase in the band-gap transition with the increase of silica. The silica-modified TiO2 nanoparticles exhibited better photocatalytic activity, which increased with the silica amount, in comparison with pure TiO2 nanoparticles. Due to better thermal stability, the photocatalytic activity of the silica-modified TiO2 sample held good photocatalytic activity even after calcined at 1273 K.     

Laponite-supported titania photocatalysts

This study builds on previous results published on the synthesis and characterization of laponite-supported titania photocatalysts. Titania nanocrystals are prepared prior to addition to the clay dispersion, by a sol-gel synthesis incorporating a microwave hydrothermal step. In addition to previously examinations with XRD, TEM, and FT-IR, the samples are further characterized with SEM, 29Si NMR, and BET N2 sorption to gain additional insight into the effect of TiO2 concentration and surface area on the photoactivity of the samples.     

中空纳米二氧化硅微球的制备及表征

本文介绍了一种制备中空纳米二氧化硅微球的新方法。利用模板首先合成介孔纳米二氧化硅微球,再用水热反应法,成功制备了非功能化和巯基、氨基功能化中空纳米二氧化硅微球。利用透射电子显微镜,热重分析等手段对其形貌进行了表征。另外,对中空介孔纳米二氧化硅微球的形成机制进行了探讨。     

Fabrication of rutile rod-like particle by hydrothermal method: an insight into HNO3 peptization

In this work, well-crystallized and well-dispersed rod-like TiO(2) rutile particles were prepared by hydrothermally treating acid-peptized TiO(2) sols at relatively low temperatures of 200 and 240 degrees C. Raman spectra, transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the peptized sols before and after hydrothermal treatment. The results showed that HNO(3) peptization of amorphous TiO(2) was able to promote, at room temperature, the formation of crystalline phases of anatase or rutile, at low (HNO(3)/Ti=1) or at high (HNO(3)/Ti=4) concentrations of peptizer, respectively. However, after hydrothermal treatment, well-crystalline rutile developed independent of the starting concentration of the peptizer. The formation of well-dispersed rutile particles is attributed to high long-range electrostatic forces between particles in the presence of the high concentration of the peptizer. The acid peptization would easily break the oxolation bonds between triple bond Ti-O-Ti triple bond, promote the formation of titanium species with fewer oxolation bonds depending on the amount of acid, and create conditions for the formation of rutile nuclei after structural rearrangements.     

静电纺丝-碱热法制备高活性由纳米片组装的TiO2纳米纤维（英文）

半导体光催化有望解决日益严峻的环境污染与能源危机,因而得到广泛重视.纳米TiO2因为其强的氧化能力和良好的(光)化学稳定性与生物相容性,成为了最受欢迎的半导体光催化材料.到目前为止,材料科学家们制备了多种形貌的TiO2光催化材料,如纳米棒(线)、纳米片和空心微球等.作为染料太阳能电池的光阳极材料,小颗粒尺寸的纳米TiO2具有大的比表面积,有利于敏化剂的吸附,从而增强太阳能电池的光电转换性能.但是尺寸太小的TiO2颗粒不利于光散射,导致入射的太阳光直接穿透光阳极薄膜而不利于吸收和利用太阳光.为了解决敏化剂吸附和增强光散射这对矛盾,本文设计制备了由纳米片组装的TiO2纳米纤维:(1)首先通过静电纺丝法制备TiO2纳米纤维前躯体;(2)将TiO2纳米纤维前驱体在500°C焙烧,去除有机物,得到晶化度良好的由纳米颗粒组装的TiO2纳米纤维;(3)将TiO2纳米纤维进行NaOH碱热处理,使TiO2纳米颗粒转化成钛酸盐纳米片,然后经历酸洗和焙烧,得到由纳米片组装的TiO2纳米纤维.染料敏化太阳能电池的性能测试结果显示,碱热2.5 h所得TiO2样品的光阳极薄膜的光电转化效率提升了2.3倍;同时,利用丙酮光催化分解的活性来评价纳米纤维的光催化活性,发现碱热2.5 h所得纳米纤维上光催化降解丙酮的活性提升了3.1倍.结构表征结果显示,随着碱热时间的延长,从纤维表面生长出来的纳米片逐渐变长,催化剂的比表面积和孔容不断增加.大的比表面积有利于底物的吸附,纳米片结构有利于增强光散射,通过延长光程增强对光的利用效率,从而提升纳米纤维的光活性.光电流测试的结果显示,与碱热前的TiO2纳米纤维相比,碱热后的TiO2纳米纤维光电流显著增强,这是由于纳米片结构减小了扩散距离,有利于光生载流子快速转移到催化剂表面,引发丙酮的光催化氧化.     

磷钨酸钾模板法制备高活性二氧化钛空心微球

TiO2空心微球因具有低密度、高活性、易分离而有利于多次重复使用的优点而广受关注.本文介绍一种无氟制备TiO2空心微球的简单方法——磷钨酸钾(K3PW12O40)模板法.首先,将H3PW12O40和KCl溶液混匀,得到白色牛奶状的K3PW12O40模板(式(1)),然后在磁力搅拌下加入一定量的Ti(SO4)2粉末,加热至大约125oC开始回流.回流8 h后,过滤洗涤.滤饼分散在强NaOH溶液中,原位除去K3PW12O40模板(式(2)).最后,将催化剂洗涤到滤液为中性,干燥后即得到TiO2空心微球.3KCl + H3PW12O40= K3PW12O40ˉ+3HCl (1) K3PW12O40+24NaOH =12Na2WO4+ K3PO4+12 H2O (2) Ti(SO4)2+2H2O = TiO2+2H2SO4(3)我们将所制备的TiO2空心微球,采用X射线衍射、透射电子显微镜、扫描电子显微镜、傅立叶红外光谱、固体粉末漫反射和X射线光电子能谱等进行了表征.采用紫外光催化降解阴离子染料(活性嫣红X3B)来评价催化剂的性能.实验结果显示：(1)所制TiO2空心微球直径在0.5–1.0μm;(2)磷钨酸钾模板剂充当晶核,有利于空心微球的晶化;(3)加入的高浓度硫酸钛,水解产生大量的硫酸,抑制硫酸钛水解,不利于TiO2空心微球的晶化(式(3));(4)催化剂的活性随着硫酸钛量的增加而先增后降.4 mmol硫酸钛用量的TiO2空心微球具有最高的光催化活性,是TiO2颗粒样品(无磷钨酸钾模板法制备)的2.1倍.用该方法制备的TiO2空心微球活性高可归因于以下主要原因：(1)TiO2空心微球独特的孔结构;(2)良好的晶化程度(TiO2样品晶化度越高,越有利于光生载流子的分离,抑制复合);(3)样品残余磷钨酸钾模板和TiO2之间存在光生电子转移,有利于空心微球TiO2活性的提高.该法具有操作简单、重复性好、易于批量制备的等优点,有望广泛应用于(光)催化、电化学、分离与纯化以及药物缓释等领域.     

Chelating ligand-mediated synthesis of hollow ZnS microspheres and its optical properties

Monodispersed hollow ZnS microspheres have been successfully synthesized by a facile ethylenediamine tetraacetic acid (EDTA) mediated hydrothermal route. The sizes of the hollow spheres vary from 1.5 to 3.5 microm when the reaction temperature varied from 130 to 230 degrees C. The formation of these hollow spheres is attributed to the oriented aggregation of ZnS nanocrystals around the gas-liquid interface between H(2)S and water. EDTA plays important role as chelating ligand and capping reagent, which regulates the release of Zn(2+) ions for the formation of ZnS hollow spheres. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy, photoluminescence, and Raman spectroscopy. The obtained ZnS hollow spheres show a sharp and photostable UV emission approximately 370 nm, which is attributed to the recombination process associated with interstitial sulfur vacancy.