Ammonia Room Temperature Gas Sensor Using Different TiO2 Nano-structure

Abstract In this study, TiO2 Nano-structure were synthesized by three different processes including nanowires, nanoparticles and thin- films. The morphology and crystal structure of the three different TiO2 structures deposited on quartz glasses were characterized by XRD, SEM and FTIR. It has been found that nanowires and nanoparticles showed only the anatase phase while the thin-film exhibited both anatase and rutile phases. The three TiO2 Nano-structures were then used to fabricate gas sensors for ammonia (NH3) detection at different concentrations and various conditions. The samples fabricated with thin-film TiO2 towards 50 ppm NH3 showed a response value of 5% at room temperature, whereas the other two samples exhibited much higher values towards similar condition NH3 at room temperature. Samples with nanowires showed a three-fold increase and samples with nanoparticles exhibit a two-fold increase in response value. We have found that the response of all samples increases with elevating the operating temperature up to 200°C. Increasing the operating temperature improved the nanoparticle sensing conditions more than the other two samples. The samples using nanoparticles showed a 33% increase in response towards 50 ppm NH3 at 200°C compared to the samples with thin films at similar conditions. Further, response and recovery time were investigated and reported in this study.