Titanium dioxide nanoreactor February 21, 2013 The nanoparticles crystallize in a polymer network at room temperature. Credit: HZB Tiny particles of titanium dioxide are found as key ingredients in wall paints, sunscreens, and toothpaste; they act as reflectors of light or as abrasives. However with decreasing particle size and a corresponding change in their surface-to-volume ratio, their properties change so that crystalline titanium dioxide nanoparticles acquire catalytic ability: Activated by the UV component in sunlight, they break down toxins or catalyze other relevant reactions. 据物理学家组织网（ Phys.org ） 2013 年 2 月 21 日 报道，德国柏林 Helmholtz-Zentrum 材料与工程股份有限公司（ Helmholtz-Zentrum Berlin für Materialien und Energie GmbH ）软物质与功能材料研究所（ Institute for Soft Matter and Functional Materials ）以及 柏林洪堡大学 （ Humboldt University Berlin ）的研究人员合作，成功研制出一种 TiO 2 纳米反应器。 在室温条件下， TiO 2 纳米颗粒在聚合物网络结构中结晶（见图示），其中 PS 是聚苯乙烯（ polystyrene 的缩写），直径大约在 160 nm, 与 PS 周围的聚合物网状结构一起直径在 260 nm 左右。热敏核壳 PS-PNIPAM （聚苯乙烯 - 聚（ n- 异丙基丙烯酰胺 ） ， poly(n-isopropylacrylamide) ） 的合成与以前报道的合成方法不同， 首先是通过传统的乳液聚合在 PS 核的外面包裹 薄薄的一层共聚 PNIPAM ，再在室温下与 Ti(OEt) 4 反应在 PS 核外的网状结构中沉积出纳米 TiO 2 （直径 6 nm ） 微粒 。 微小的 TiO 2 粒子主要作为一种配料应用于墙漆（涂料）、防晒霜以及牙膏等产品，其作用是反射阳光，免遭晒伤或作为磨料使用。然而，随着其粒子大小的降低，势必引起表面体积比的相应变化 , 其属性也会出现变化。晶体 TiO 2 纳米颗粒可以获得催化能力 : 通过阳光紫外线激活 , 使其具有分解毒素或对其他相关反应发挥催化作用。 现在 , 德国柏林亥姆霍兹中心（ Helmholtz Centre Berlin ）的 Katja Henzler 博士和其他化学家已经开发出一种合成方法可以在室温下生产纳米粒子。这是迄今为止，关于聚合纳米反应器应用研究过程中取得的重要的研究进展 , 因为以前的研究，必须使纳米粒子完全加热使其结晶。但是，最新的合成步骤由于是在 PNIPAM 网络结构的特殊环境内进行，加热过程则可以免除。 Katja Henzler 博士 带领的研究团队制得的聚合物纳米反应器是由 PNIPAM 链形成的网状结构将聚苯乙烯核包围起来而构成的。将一种钛化合物（即 Ti(OEt) 4 ）添加到一种聚合物胶体的乙醇溶液中 , 聚合物胶体会触发在 PNIPAM 网状结构中形成细小的 TiO 2 粒子。实验结果表明 , 化学家能够控制这些过程的速度 , 同时影响已经形成的纳米晶体的质量。在实验过程中，联合使用 x 射线显微术和光谱学 (NEXAFS-TXM,U41-SGM) 。 Katja Henzler 博士和显微镜研究团队的研究结果已经表明 , TiO 2 纳米粒子在聚合物纳米反应器内整体分布是均匀的。研究人员为了防止人工形成导致样品干燥，他们在低温水环境条件下检查了得到的样品。分析结果表明 , TiO 2 纳米粒子都具有同样的晶体结构即正方锐钛矿结构，这种晶体结构使其具有催化特性的关键。 TiO 2 在自然界中存在 3 种晶体结构：即金红石型、锐钛矿型以及板钛矿型。其中金红石型和锐钛矿型 TiO 2 具有较高的催化活性，尤以锐钛矿型 TiO 2 光催化活性最佳。 研究人员声称他 们新分析方法可以实现对合成粒子质量的控制 , 这样就可以根据特定应用进行最优化处理。 更多信息请浏览： http://doc.sciencenet.cn/DocInfo.aspx?id=16925
J. Electrochem. Soc. / Volume 158 / Issue 5 / Fuel Cells and Energy Conversion Effect of Titanium Dioxide Supports on the Activity of Pt-Ru toward Electrochemical Oxidation of Methanol J. Electrochem. Soc., Volume 158, Issue 5, pp. B461-B466 (2011)(Published 10 March 2011) ABSTRACT REFERENCES (20) Roderick E. Fuentes , Brenda L. García , and John W. Weidner Department of Chemical Engineering, University of South Carolina, Columbia, South Carolina 29208, USA TiO 2 and Nb-TiO 2 were investigated as stable supports for Pt-Ru electrocatalysts towards methanol oxidation. X-ray photo-electron spectroscopy (XPS) data for all these TiO 2 -based supports show oxidation states of Ti 4+ , with no Ti 3+ , suggesting low electronic conductivity. However, the deposition of metal nanoparticles onto the supports at loadings of 60 wt% metal dramatically increased conductivity, making these electrodes (metal particles + support) suitable for electrochemistry even though the supports have low conductivity. For some of these TiO 2 -based supports, the activity of Pt-Ru towards methanol oxidation was excellent, even surpassing the activity of the same electrocatalysts supported on carbon. The activity of the electrocatalyst depended on TiO 2 crystalline structure, the addition of Nb into the support and the weight loading of metal. For example, using anatase Nb-TiO 2 as a support increased the electrochemical activity of Pt-Ru by 83% compared to the same electrocatalysts supported on either carbon Vulcan XC-72R or rutile Nb-TiO 2 . This electrode was also 64% more active than the one that had anatase TiO 2 as the support with no Nb. Finally, increasing the weight loading of metal from 5 to 60% increased the conductivity by 5 orders of magnitude and the activity by a factor of 20. 2011 The Electrochemical Society History: Submitted 1 June 2010; revised 24 January 2011; published 10 March 2011 Permalink: http://dx.doi.org/10.1149/1.3559495
Journal of Power Sources Article in Press, Accepted Manuscript - Note to users doi:10.1016/j.jpowsour.2011.01.077 | How to Cite or Link Using DOI Copyright 2011 Published by Elsevier B.V. Permissions Reprints Mesoporous polyaniline/TiO2 microspheres with core-shell structure as anode materials for lithium ion battery C. Lai a , H.Z. Zhang a , G.R. Li a and X.P. Gao , a , a Institute of New Energy Material Chemistry, Tianjin Key Laboratory of Metal and Molecule Based Material Chemistry, Nankai University, Tianjin 300071, China, Received 7 November 2010; revised 7 January 2011; accepted 20 January 2011. Available online 28 January 2011. Abstract Mesoporous polyaniline/anatase TiO2 composite microspheres with the core-shell structure for lithium-ion battery applications are prepared via a facile hydrothermal route. The structure of as-prepared sample is characterized by electron microscopy (TEM), and scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area. It is suggested that the formation of the core-shell structure can be designated as a two-step assembly process induced by the polymerization of the aniline. The electrochemical tests demonstrate that the discharge capacity of the as-prepared polyaniline/anatase TiO2 microspheres can be stably retained at 157.1 mAh g−1 after 50th cycle at the high current density of 1500mAg−1. The high rate performance of the as-prepared sample at various current densities from 200 to 2000mAg−1 is also investigated. The discharge capacity of 123.9 mAh g−1 can be obtained at the high current density of 2000mAg−1, which is about 73.4% of that at the low current density of 200mAg−1 upon cycling, indicating that the as-prepared sample can endure great changes of various current densities to retain a good stability due to the core shell mesoporous structure. Keywords: Lithium-ion batteries; Titanium dioxide; Polyaniline; Mesoporous; Core-shell.
Preparation and spectroscopic characterization of quantum-size titanium dioxide， Preparation and spectroscopic characterization of ，Chemical Journal on Internet， 2000， 17-17
标签: 二氧化钛
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