Development of semiconductor metal oxide gas sensors modified by mesoporous silica materials

Abstract

Recently mesoporous materials (such as MCM-41 and SBA-15) have attracted considerable attention due to their highly-ordered pore structure and high specific surface area. Therefore, it is of great interest to apply such mesoporous materials as support for metal oxide gas sensor to improve the sensitivity. In this study, a simple chemical mixing method has been successfully applied for the synthesis of a new composite gas sensor (SnO2/mesoporous material) with superior gas sensitivity. The N2 isotherms, O2-TPD, TPR and XPS results reveal for the first time that the increase of the amount of surface-adsorbed-oxygen played an important role in increasing the sensitivity of such composite. This surface-adsorbed-oxygen enhancing mechanism has also been verified using various types of silica and non-silica materials as sensor supports. In order to improve the sensitivity further, noble metal has been introduced into the composite sensing system, and much higher sensitivities and selectivities have been achieved.