One-dimensional Nanostructured TiO₂ And SrTi_1-xFe_xO₃?x=0,0.35? For Gas Sensing

Metal-oxide semiconductor(MOS) based gas sensors have attracted much attention in recent years. In this work, one-dimensional TiO2 and SrTi0.65Fe0.35O3 nanofibers were prepared by electrospinning, and TiO2 nanotubes by anodic oxidation, and their gas(CO and O2) sensing performances were investigated. TiO2 nanofibers, Pd decorated TiO2 nanofibers and highly ordered arrays of TiO2 nanotubes showed high sensitivity to CO, and SrTi0.65Fe0.35O3 nanofibers showed good sensitivity to O2.Therefore, the sensor performances could be dramatically improved by surface decoration and morphology modification.In Chapter 1, gas sensing mechanism and electrospinning technology are briefly introduced, and the state-of-art of one-dimensional MOS nanostructures for gas sensing is elaborated.In Chapter 2, our works about TiO2 nanofibers and nanotubes are summarized. The influences of electrospinning parameters on the morphology of nanofibers, in the case of TiO2, were explored. To demonstrate the effects of morphology on the gas sensing behaviors, the CO gas sensing performances of TiO2 nanofibers, Pd decorated TiO2 nanofibers(average diameter is 180 nm), and TiO2 nanotube arrays(diameter150 nm and tube wall thickness 10 nm) were compared.In Chapters 3 and 4, our work about SrTi1-x FexO3(x = 0, 0.35) nanofibers are summarized. SrTi1-xFexO3(x = 0, 0.35) nanofibers were prepared by electrospinning, and the electrical properties and oxygen sensing performance of SrTiO3 thick film and SrTi0.65Fe0.35O3 nanofibers were explored. At 750 °C, the response of the nanofibers to 1%O2 was 2.5, and response time and recovery time were 5 s and 40 s, respectively. As to 0.1%O2, the response time was less than 2 s, with recovery time of about 20 s.