Improvement of Recovery of SnO2-Based Thick Film Gas Sensors for Dimethyl Methylphosphonate (DMMP) Detection

Response and recovery behaviors of SnO2-based gas sensors promoted with MoO3 and Sb2O3 were investigated under a very low concentration of dimethyl methylphosphonate (DMMP) in a flow system. The SnO2-based gas sensor, promoted simultaneously with MoO3 and Sb2O3, showed not only good sensor response in the detection of the DMMP (0.1-0.5 ppm), but also a complete recovery by means of the thermal treatment in air. In particular, the Mo5Sb1(P) sensor, which was prepared by the physical mixing of 5 wt% MoO3, 1 wt% Sb2O3, and SnO2, showed a high sensor response of about 40% in the detection of 0.5 ppm of DMMP at 350 degrees C, and its sensor response was maintained during multiple cycles of detection and recovery. The roles of additives and the effects of physical properties such as pore diameter and surface composition of the sensing material on the sensor response and recovery were discussed.