Lyson-Sypien, B. and Czapla, A. and Lubecka, M. and Zakrzewska, K. and Radecka, M. and Kusior, A. and Balogh, A. and Lauterbach, S. and Kleebe, H.-J. (2012):
Gas sensing properties of TiO2 - SnO2 nanomaterials.
In: 14th International Meeting on Chemical Sensors, pp. 1611-1614, AMA Association for Sensor Technology, ISBN 978-3-9813484-2-2,
[Book Section]

Abstract

Nanocomposites of TiO2/SnO2 for hydrogen and ammonia detection are compared with complex oxides that belong to TiO2/SnO2 system. Nanocomposites have been prepared by mechanical mixing of nanopowders with different specific surface area SSA=159 m2/g for TiO2 and SSA=21 m2/g for SnO2 as determined from BET measurements. Complex oxides have been synthesized by sol - gel method from organic precursor of TTIP and SnCl2*2H2O. The resulting SSA=91 m2/g has turned out to be larger for 50 mol % TiO2 + 50 mol % SnO2 sol-gel sample as compared with 65 m2/g for the nanocomposite of the same nominal chemical content. Nanocomposites consist of two separate phases of larger-grain (21-28 nm) cassiterite SnO2 and smaller-grain (8-11 nm) rutile TiO2, respectively, over a full compositional range. XRD and STEM suggest that a solid solution with some precipitation of SnO2 is formed for 50 mol. % TiO2 + 50 mol. % SnO2. For nanocomposites, TEM experiments reveal the presence of small, elongated TiO2 crystals and larger SnO2 crystals of irregular shape. For 50 mol.% TiO2 + 50 mol.% SnO2 sol - gel sample, spherical, homogeneously distributed grains are seen in TEM. Sensor responses exhibit a broad maximum over the compositional range at 20 - 50 mol.% of TiO2 mixed with SnO2. The electrical resistivity of 50 mol % TiO2 + 50 mol % SnO2 sol-gel sample is less affected than that of the nanocomposite of the same composition, by the exposure to H2 and NH2 at elevated temperatures.

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