Fabrication and its characteristics of metal-loaded TiO2/SnO2 thick-film gas sensor for detecting dichloromethane

This study investigated sensitivity of the gas sensor to chemical warfare agents with the various operating temperatures and catalysts. The nano-sized SnO2 powder mixed with metal oxide (TiO2) was doped with transition metals (Pt, Pd and In). Thick film of nano-sized SnO2 powder and TiO2 was prepared by screen-printing method onto Al2O3 substrates with platinum electrode and chemical precipitation method. The physical and chemical properties of sensor material were investigated by SEM/EDS, XRD and BET analyzers. The measured sensitivity to simulant chemical toxic gas is defined as the percentage of resistance of value equation, (Ra − Rg/Ra), that of the resistance (Rair) of SnO2 film in air and the resistance (Rgas) of SnO2 film in dichloromethane. The best sensitivity and selectivity of these thick-film sensor were shown with 1 wt.% Pt and 5 wt.% TiO2 for dichloromethane toxic gas at the operating temperature of 250 °C.