SnO2-Au nanocomposite synthesized by successive ionic layer deposition method: Characterization and application in gas sensors

Abstract

A possibility of synthesizing the SnO2-Au nanocomposite by the successive ionic layer deposition (SILD) method is demonstrated in this article. It is shown that as a result of successive treatments in solutions of Sn(OH)(x)FyClz and HAuCl4 the SnO2-Au nanocomposite with a Sn/Au ratio varying from 1:1 to 6:1 can be formed on the surface of substrates. It is found that the value of this ratio depends on the concentration of F ions in solution. The gold in the indicated composite is in the metallic state. The growth of the SnO2-Au composite takes place through the formation of 3-D precipitates, which form a continuous film after 13 deposition cycles. As a result, a layer with averaged thickness of up to 20 nm is formed on the surface. Nanocomposite films, even after treatment at an annealing temperature T-an similar to 600 degrees C, have finely dispersed structure. The size of the Au clusters incorporated in the SnO2 matrix is in the range from 3 to 15 nm. Gas sensing characteristics of SnO2 films modified by SnO2-Au nanocomposites are discussed as well. It is shown that surface modification by SnO2-Au nanocomposites can be used for improving operating characteristics of conductometric SnO2-based gas sensors. (C) 2011 Elsevier B.V. All rights reserved.