NOTES Chinese Science Bulletin Vol. 45 No. 16 August 2000 1533 Morphological structure and physicochemical properties of nanotube TiO 2 ZHANG Shunli 1 , ZHOU Jingfang 1 , ZHANG Zhijun 1 , DU Zuliang 1 , A.V. Vorontsov 2 & JIN Zhensheng 1 1. Labaratory of Lubrication and Functional Materials, Henan University, Kaifeng 475001, China; 2. Boreskov Institute of Catalysis, Novosibirsk 630090, Russia Correspondence should be addressed to Zhang Zhijun or Jin Zhensheng Abstract Morphological structure and physicochemical properties of nanotube TiO 2 were investigated. It was found that the TiO 2 nanotube consisted of 2 5 monolayers of TiO 2 molecules, and its inner diameter was between 4.2 and 5.9 nm. The nanotube TiO 2 powder had high specific surface area and pore volume (379 m 2 /g and 1.431 cm 3 /g respectively) and its decolorization activity for Reactive Brilliant Red X-3B was 2 times higher than that of raw TiO 2 (p-25). This new type of TiO 2 was hopeful for application in photocatalysis and composite nanomaterial. Keywords: nanomaterial, nanotube, titania, photocatalyst, decolorization of reactive dye. TiO 2 has widely drawn increasing attention in its use as a catalyst or as a support in environmental photocatalysis. A main limitation to the use of TiO 2 obtained by conventional methods is its low surface area. There are some ways to be studied for obtaining TiO 2 with larger surface area, e.g. using surfactant tetradecylphosphate [1] and biopolymer chistosan [2] as template to synthesize mesoporous TiO 2 , and using the supercritical drying method to prepare aerogel TiO 2 [3] . Recently, some people developed methods to deposit titania sol within the pores of template membrane (such as alumina membrane) to produce tube type of TiO 2 , but the tube diameter is larger (ca. 200 nm). In this note, the morphological structure and physicochemical properties of nanotube TiO 2 , synthesized after Kasuga’s work [4] , were investigated. The results showed that this type of nanotube TiO 2 had larger surface area and smaller size than those of mesoporous and tube type TiO 2 , synthesized by Hoyer [5] and Lakshmi et al. [6] . 1 Experiment Degussa TiO 2 was used as the raw material for preparation of nanotube TiO 2 . Transmission electron microscopy (TEM), energy dispersion spectroscopy (EDS) analysis, and electron diffraction (ED) of raw TiO 2 and nanotube TiO 2 were carried out with JEM 1200EX/S apparatus. High resolution transmission electron microscopy (HRTEM) patterns (1.25×10 6 ) of nanotube TiO 2 were taken in Boreskov Institute of Catalysis, Russia. BET surface area and BJH pore volume were determined with ASAP 2010 apparatus (produced by Micromeritics). Fourier transform infrared spectra (FTIR) and UV- visible diffuse reflectance spectra (DRS) were obtained on Nicolet Avatar 360 and Hitachi 2010, respectively. 2 Results and discussion TEM photographs of raw TiO 2 and nanotube TiO 2 are shown in fig 1. Nanotube sample A was calcined at 500 for 5 h in air (fig.1(b)), nanotube sample B was dried at 100 (fig. 1(c)). The nanotube length of sample B is ca. 500 nm (fig.1(d)), its observed layer number is less than that of sample A and its picture contrast is not so striking as that of sample A (fig. 1(b, c)). It can be seen that the nanotube structure of sample A calcined at 500 is not destroyed, but the local sintering and twisting has happened (fig. 1(b)). All of the nanotubes are open and consist of 2 5 monolayers of TiO 2 molecule, and their schematic diagrams are shown in fig. 2. The parameters of the morphological structure of TiO 2 nanotube calculated according to fig. 1(b, c) are listed in table 1. The thickness of one monolayer equals 0.2 — 0.3 nm, and it closes to the diameter of anion O 2- , which indicates that each monolayer represents a TiO 2 molecular layer. The nano tube inner diameter varies with the monolayer number: 5.9 nm for double layer nanotube and 4.2 nm for five layer nanotube (fig. 2). Therefore, this type of TiO 2 provided a new precursor for assembling composite materials, i.e. some nanosized metal