Pd-doped TiO2 film sensors prepared by premixed stagnation flames for CO and NH3 gas sensing

Abstract

This paper synthesized Pd-TiO2 films by the flame stabling on a rotating surface (FSRS) technique with different doping ratios of Pd. The semiconductor metal oxide (SMO) particles together with Pd additive condensed in the post flame zone, and then deposited directly on a sensor subtract which is fixed on a rotating plant to form the sensing films. The composition and structure of sensing films were assessed with TEM, SEM, XPS, XRD and EDS techniques. It was found that TiO2 particles prepared by the FSRS technique had diameters ranging from 9 to 17 nm and are in anatase type. Pd-doped TiO2 films remained porous anatase and Pd element dispersed well in the TiO2 film. The sensing test results showed that the nano film sensors synthesized by FSRS technique responded rapidly to CO concentration change while rather slowly to NH3 concentration change. The doping Pd improved the response sensitivity of TiO2 sensor remarkably for CO sensing, and a certain extent for NH3. An optimal doping ratio existed and the TiO2 film sensor sample with 1.0 wt.% Pd-doping ratio had the best gas sensing performance.