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Article

Impact of Structure and Morphology on Gas Adsorption of Titanate-Based Nanotubes and Nanoribbons

Polona Umek,^† Pavel Cevc,^† Adolf Jesih,^† Alexandre Gloter,^‡^§ Christopher P. Ewels,^‡ and Denis Ar

Institute Jozef Stefan, Jamova 39, 1000 Ljubljana, Slovenia, Laboratoire de Physique des Solides, CNRS UMR8502, Universit Paris-Sud, Orsay, France, ICYS, National Institute for Materials Science, Namiki 1-1, Tsukuba 305-0044, Japan, and Faculty of Mathematics and Physics, Jadranska 19, University of Ljubljana, Ljubljana, Slovenia

Chem. Mater., 2005, 17 (24), pp 5945–5950

DOI: 10.1021/cm050928w

Publication Date (Web): November 2, 2005

†

Institute Jozef Stefan.

‡

Université Paris-Sud.

National Institute for Materials Science.

Corresponding author. Fax: + 386 1 4773-191. Tel: + 386 1 4773-492. E-mail: denis.arcon@ijs.si.

University of Ljubljana.

Abstract

We report on the synthesis of titania-based nanotubes and nanoribbons prepared by hydrothermal methods, as well as evaluating their structure and adsorption properties. Nanotubes were found to be hollow scrolls with a typical outer diameter of about 10 nm, inner diameter 4−5 nm and length of several hundred nm. The nanoribbons are highly crystalline, typically 40 nm in cross-section and up to a few μm in length. All these samples were exposed to a NO₂ atmosphere in order to test their adsorption properties using electron paramagnetic resonance (EPR). The nanotubes were found to have high active surface areas of about 250 m²/g. When exposed to NO₂ gas, NO₂ molecules tend to physisorb on the nanotube surface via the nonbonding p_y orbital of the oxygen atoms. In contrast nanoribbons have much smaller active surface areas (30 m²/g). The dominant EPR signal now comes from NO molecules adsorbed on Na⁺ ions. These results show that titania-based nanotubes and nanoribbons may represent an attractive option for the removal and catalysis of nitrogen oxides in future.