Silica-Tin Oxide Sensor with Molecular Recognition Ability

Abstract

This article reviews a novel technique to create a molecular recognition ability based on the molecular shape on a tin oxide semi-conducting sensor. The surface of the tin oxide was covered by a thin layer of silica using the chemical vapor deposition (CVD) method after the adsorption of aldehyde. Later the aldehyde was removed. The silica filled the micropores whose shape and size were controlled by the template aldehyde molecule, as evidenced by the selective chemisorption behavior. Thus, the modified silica/tin oxide showed shape-selective sensing ability. The sensor prepared with benzaldehyde as the template showed low sensitivity to cyclohexane (cyclic) and 2,2-dimethylbutane (dimethylbranched), while it showed high sensitivity to 2-methylpentane (monomethyl-branched) and hexane (linear). The sensor prepared with butanal showed low sensitivities to the cyclic, dimethyl-branched and monobranched molecules and showed high sensitivity only to the linear molecule. Thus, these sensors could distinguish the presence of a single methyl branch on an alkane molecule. The molecular recognition ability was also demonstrated for alcohols and aldehydes. The preparation process is given in detail.