A wide range sensor of a 3D mesoporous silica coated QCM electrodes for the detection of volatile organic compounds

Abstract

A quartz crystal microbalance (QCM) electrode coated with high surface area mesoporous silica KIT-6 films was designed as a sensor for the detection of a wide range of volatile organic compounds (VOCs) such as aliphatic alcohols, aliphatic amines, benzene and toluene at room temperature. A thin film of KIT-6 coating on Au-electrode of QCM was prepared by a simple drop-coating approach. The mesoporous silica KIT-6 was characterized with transmission electron microscope (TEM), low-angle X-ray difraction (XRD), Fourier transform infrared spectrocsopy (FT-IR) and N2 sorption isotherm. The frequency shifts (Δf) of the QCM coated with mesoporous silica KIT-6 films were measured as a function of time after injection of different VOCs vapors. Δfs were found to be increased linearly with the injected chemical vapor concentration. The results definitely showed an enhanced detection sensitivity and a fast response of the QCM sensor. The sensor showed an unusual high sensitivity and selectivity for amine compounds and the equilibrium was achieved within few seconds. The adsorption kinetics and relaxation time of methanol and ethanol vapors were carefully studied.