Response time and mechanism of Pd modified TiO2 gas sensor

In this work, gas response properties of Pd modified TiO2 sensing films are discussed when exposed to H2 and O2. TiO2 films are surface modified in PdCl2-containing solution by the dipping method and treated for different treatment times to get different surface states. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Kröger-Vink defect theory are used to characterize the sensing films. The gas response properties indicate that the sensor response time which related to the rate of change of sensor resistance is affected by the activation energy (E). In particular, the sensor treated at 900 °C for 2 h exhibits a response time of about 20-240 ms when exposed to H2 and 40-130 ms when exposed to O2 at 500-800 °C.