Hydrothermal synthesis and characterization of nanorods of various titanates and titanium dioxide
Hydrothermal synthesis and characterization of nanorods of various titanates and titanium dioxide
复制标题
DOI：
10.1021/jp055687u
复制
发表时间：
2006-03-09
影响因子：
3.3
通讯作者：
Yoshimura, M
中科院分区：
文献类型：
--
作者：
Kolen'ko, YV;Kovnir, KA;Yoshimura, M
研究了无定形二氧化钛-氨水凝胶水热合成二氧化钛基纳米棒的形成过程。在浓NaOH水溶液存在下，用简单的水热法制备了棒状的三钛酸钠(Na2Ti3O7)粒子。合成的Na2Ti3O7纳米棒在超声波作用下与HCl发生离子交换反应，促进了Na2Ti3O7纳米棒的完全钠取代和H_2Ti3O7纳米棒的形成。Na2Ti3O7和H2Ti3O7纳米棒的低温热处理分别导致六钛酸钠(Na2Ti6O13)和亚稳态的TiO2B相的层状晶体结构的丧失和纳米棒的形成。这些转变在粒子形态没有明显变化的情况下进行。采用扫描电子显微镜(SEM)、粉末X射线衍射仪(XRD)、Brunauer-Emmett-Teller(BET)法、热重分析(TGA)和拉曼光谱等手段对纳米结构进行了表征。用高分辨电子显微镜对合成的纳米棒的结构缺陷进行了研究。平面缺陷的存在可以归因于锯齿状的带状层剥离成二维的钛酸盐以及TiO6八面体的层凝聚成三维骨架。
The formation process of titania based nanorods during hydrothermal synthesis starting from an amorphous TiO2-nH(2)O gel has been investigated. Sodium tri-titanate (Na2Ti3O7) particles with a rodlike morphology were prepared by a simple hydrothermal process in the presence of a concentrated NaOH aqueous solution. The ion exchange reaction of the synthesized Na2Ti3O7 nanorods with HCl under ultrasonic treatment promotes a complete sodium substitution and the formation of H2Ti3O7 nanorods. Low-temperature annealing of the as-produced nanorods of Na2Ti3O7 and H2Ti3O7 leads to a loss of the layered crystal structure and the formation of nanorods of condensed framework phases-sodium hexa-titanate (Na2Ti6O13) and metastable TiO2-B phases, respectively. These transformations proceed without a significant change in particle morphology. The nanostructures were investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), and Raman spectroscopy. The structural defects of the synthesized nanorods were investigated by high-resolution electron microscopy. The presence of planar defects can be attributed to the exfoliation of the zigzag ribbon layers into two-dimensional titanates as well as to the condensation of the layers of TiO6 octahedra into three-dimensional frameworks.