Electrochemical Energy Laboratory Materials Science and Engineering Program, University of Texas at Austin, Austin, Texas 78712, USA.
Inorg Chem. 2012 Mar 19;51(6):3505-12. doi: 10.1021/ic202239n. Epub 2012 Mar 1.
The various polymorphs (anatase, rutile, and brookite) of TiO(2) with different nanomorphologies have been synthesized by a facile microwave-assisted solvothermal process without surfactants, employing TiCl(4) or TiCl(3) as precursors in various alcohol (ethanol, propanol, butanol, and octanol) media. The samples have been characterized by X-ray diffraction (XRD), electron microscopy, and Brunauer-Emmett-Teller (BET) surface area analysis. The Ti/Cl ion concentration, reaction pH, and size of the alcohol molecule are found to control the morphology, crystal structure, and crystallite size of the TiO(2) particles. Among the various TiO(2) polymorphs synthesized, the rutile TiO(2) spheres built up of nanorods that were synthesized with TiCl(4) in octanol have an average pore size and surface area of, respectively, 5 nm and 404 m(2)/g and exhibit the best electrochemical performance with a capacity of >200 mAh/g after 100 cycles and high rate capability. The excellent electrochemical properties originate from the nanorod-building morphology and mesoporosity of TiO(2) spheres that provide good electrical contact, accommodates the strain smoothly, and facilitates facile lithium-ion diffusion.
各种 TiO(2)多晶型物（锐钛矿、金红石和板钛矿）具有不同的纳米形态，已通过无表面活性剂的简便微波辅助溶剂热工艺合成，使用 TiCl(4)或 TiCl(3)作为前驱体在各种醇（乙醇、丙醇、丁醇和辛醇）介质中。样品通过 X 射线衍射（XRD）、电子显微镜和 Brunauer-Emmett-Teller（BET）表面积分析进行了表征。发现 Ti/Cl 离子浓度、反应 pH 值和醇分子的大小控制着 TiO(2)颗粒的形态、晶体结构和晶粒尺寸。在所合成的各种 TiO(2)多晶型物中，锐钛矿 TiO(2)球由纳米棒组成，这些纳米棒是用 TiCl(4)在辛醇中合成的，具有 5nm 的平均孔径和 404m(2)/g 的比表面积，在 100 次循环后表现出最佳的电化学性能，容量超过 200mAh/g，并且具有高倍率性能。优异的电化学性能源于 TiO(2)球的纳米棒构建形态和中孔性，这提供了良好的电接触、顺利容纳应变和促进了锂离子的扩散。
