Upon Particle Size and Film Thinness of TiO2 Sensor Prepared by Flame Synthesis

Abstract

Nanostructured semiconducting metal oxide (SMO) gas sensor can be fabricated with flame synthesis by combusting a premixed fuel-oxidizer mixture doped with a selected metal precursor in the stagnation flow configuration. Particle size and film thickness of the SMO sensor are the most significant parameters for the sensing performance. Thus, they should be well predicted and properly controlled. In this study, some experiments on the particle size and film thickness were conducted. It was found that the particle size was mainly depended on the concentration of precursor. Results shojwed that the growth rate increase firstly then decrease with time. A TiO2 gas sensor was then prepared by flame synthesis directly with desired particle size and film thickness at a given precursor concentration. After proper post-processing, the CO sensing properties of the TiO2 sensor were tested under different testing temperatures. The sensor showed excellent performance in sensitivity and response time, and the optimal testing temperature was around 500 o C.