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

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)xFyClz 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 Tan ∼ 600 °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.