Effect of the Chemical Structure of a Self-Assembled Monolayer on the Gas-Sensing Behavior of SnO2 Nanowires

In this study, detailed investigations of the selective sensing capability of semiconducting metal oxide (SMO)-based gas sensors with self-assembled monolayer (SAM) functionalization were conducted. The selective gas-sensing behavior was improved by employing a simple and straightforward postmodification technique using functional SAM molecules. The chemical structure of the SAM molecules promoted interaction between the gas and SAM molecules, providing a gas selective sensing of SnO₂ nanowires (NWs). In addition, a bundle of SnO₂ NWs provided a large surface area that could act as a sensing site. SAM functionalization was confirmed by infrared spectroscopy and thermogravimetric analysis, and the selective gas-sensing behaviors were investigated under different sensing conditions. With variations in the chemical structures of the SAM molecules, the selective gas-sensing behaviors also changed as the corresponding intermolecular interaction forces were different. This integration of selective gas sensing and passivation of a sensing surface provides a straightforward approach for the preferred gas sensing of SnO₂ NWs. Furthermore, owing to the universal binding characteristics of SAM molecules to the metal oxide surface, this approach can be expanded to other SMO-based gas-sensing platforms.