Synthesis and Characterization of Noble Metal Tin Oxide Plasmonic Nanocomposites for Sensing Applications

Abstract

Detection of toxic gases has emerged as one of the major issues in recent years in areas such as industrial production (e.g. detection of methane in mines) [1-4], medical diagnostics [5-7], automotive industry (e.g. detection of polluting gases from vehicles) [8-12], monitoring indoor air quality (e.g. detection of carbon monoxide) [13-20] and environmental studies (e.g. green house gas monitoring) [21-24].Various methods such as gas chromatography, Fourier-transform infrared spectroscopy, mass spectrometry, chemiluminescence detection, metal oxide semiconductor based gas sensing have been used for the detection and monitoring of toxic gases. Metal oxide semiconductor gas sensors have distinct advantages than other sensors due to their lower fabrication cost, simpler design, compact size, compatibility with modern electronic devices and enhanced gas sensing performance [25-28]. Among the various metal oxide semiconductors SnO2 is considered as the most promising candidate for gas sensors due to its fascinating electrical and optical properties [29, 30]. Although gas sensors based on SnO2 nanostructures have been used these sensors suffer from limitations like poor selectivity, poor long term stability and elevated operating temperature. However, these limitations of SnO2 based gas sensors can be overcome by employing different approaches to modify their properties for improved gas sensing such as (i) doping SnO2 with metals [31, 32], (ii) decoration of SnO2 with metal nanostructures [33-35], (iii) formation of nanocomposites of SnO2 with other semiconductors [36-39] and (iv) ion irradiation [40]. These approaches are aimed at modifying the electronic band gap structure of SnO2 so that the variation in conductivity of the sensor can be tuned for improved gas sensing. newlineThis thesis explores the possibility of developing SnO2 nanostructures based highly efficient CO gas sensors by employing the above mentioned strategies. We have synthesized SnO2 nanostructures with different morphologies (nanoparticles, nanotowers...