Titania nanotubes, nanorods and nanopowder in the carbon monoxide oxidation process Anastasia V. Grigorieva a, * , Eugene A. Goodilin a, b , Ksenia L. Dubova b , Tatyana A. Anufrieva c , Lyudmila E. Derlyukova c , Alexander S. Vyacheslavov a , Yuri D. Tretyakov a, b a Materials Science Department, Lomonosov Moscow State University, Lenin Hills, Moscow 119992, Russian Federation b Chemistry Department, Lomonosov Moscow State University, Lenin Hills, Moscow 119992, Russian Federation c Institute of Problems of Chemical Physics, Acad. Semenov av. - 1, Chernogolovka 142432, Russian Federation article info Article history: Received 4 January 2009 Received in revised form 2 October 2009 Accepted 3 January 2010 Available online 18 January 2010 Keywords: Titanium dioxide Nanotubes Nanorods CO oxidation abstract Nanotubes, nanorods and nanopowders of hydrated titanium dioxide were studied with respect to their catalytic activity in a model reaction of CO oxidation. It was found that it is the nanotubular form characterized by distorted layered structure that demonstrates outstanding results in catalysis compared to all other forms. Ó 2010 Elsevier Masson SAS. All rights reserved. Numerous nanostructured forms of titania like nanopowders [1], nanotubes [2], nanorods [3], whisker [4], fibers [5], and mes- oporous materials [6] have not yet finally revealed their outstanding practical potential. Research and development of these materials are mostly imposed by their promising applications as catalyst [7], photocatalysts for purification systems [8], bio-medical and cosmetology components [9], fuel cells [10], sensors [6,11], memristors [12], efficient anode materials for batteries and power cells [13], and electrochromic materials [14]. Titanium dioxide powders serve as supports for noble metal catalysts such as gold, silver and also for some oxidic nanoparticles [15]. The catalytic activity of these materials was experimentally investigated in a few works related to the well-studied process of carbon monoxide oxidation reaction. The oxidation of CO over 3d-metal oxides occurs usually due to the Langmuir–Hinshelwood mechanism [17], thus a number of parameters of catalyst (such as specific surface area, surface concentration of acidic and basic sites, structural oxygen deficiency) become quite important. The interaction of CO molecules with the TiO 2 surface is pref- erably realized by the C-end, this orientation is more favorable than by the O-edge [16], and, therefore, the surface oxygen determines strongly adsorption and desorption processes. Hydratation of surface could also predetermine the dependence of reaction rate on specific surface area influencing on a percent of active sites. Nanopowder of titanium dioxide was prepared by a sol–gel method from tetra-n-butyl titanate Ti(C 4 H 9 O) 4 (Aldrich). Distilled water was added slowly under vigorous stirring to Ti(C 4 H 9 O) 4 (Fluka). The hydrolysis product was then dried at 70  C in air. Nanotubular titania was synthesized using a standard technique [18]. Polycrystalline anatase powder (Sigma–Aldrich) was stirred with 10 M sodium hydroxide water solution for 1 h. Then the mixture was autoclaved (80% of infilling) at 180  C for 48 h. The product of hydrothermal treatment was washed repeatedly with 1 M HNO 3 and then with deionized water until pH has reached 6. For the synthesis of nanorods, the nanopowder of TiO 2 served as a precursor. The temperature and duration of hydrothermal process were the same as in the processing of nanotubes. The content of sodium in final samples did not exceed 0.1 wt.% according to EDX data. All the samples were examined by X-ray diffraction (XRD) using Rigaku D/MAX 2500 diffractometer (Japan) with a rotating copper anode (CuKa in a 2Q range of 5–70  with a step 0.01  ). The microstructure of the samples was studied by a transmission electron microscopy (Leo 912 AB Omega (Leo, Germany), LaB 6 cathode, accelerating potential 100 kV). The surface area, pore sizes distribution were examined using nitrogen capillary adsorption * Corresponding author. Fax: þ7 495 939 09 98. E-mail address: anastasia@inorg.chem.msu.ru (A.V. Grigorieva). Contents lists available at ScienceDirect Solid State Sciences journal homepage: www.elsevier.com/locate/ssscie 1293-2558/$ – see front matter Ó 2010 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2010.01.001 Solid State Sciences 12 (2010) 1024–1028