Phthalocyanine/silica hybrid films on QCM for enhanced nitric oxide sensing

We have attempted to detect nitric oxide (NO) in gaseous state by immobilizing cobalt phthalocyanine (CoPc) in a mesoporous silica matrix deposited on a quartz crystal microbalance (QCM). CoPc/mesoporous silica hybrids are prepared by using thermal calcination process. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) are used to characterize the CoPc/silica hybrids. The sensor response towards NO is tested in a sealed gas chamber. To estimate the sensitivity enhancement introduced by the mesoporous silica film, NO response of non-modified QCM and CoPc-modified QCM are also recorded. Cross-sensitivity to potential interfering analyte such as carbon monoxide (CO) is then investigated. The experiment results show that sensitivities up to 25 ppb/Hz could be achieved by using the developed CoPc/silica hybrid on QCM. (c) 2007 Elsevier B.V. All rights reserved.