Highly Sensitive and Selective CO/NO/H2/NO2 Gas Sensors Using Noble Metal (Pt, Pd) Decorated MOx (M = Sn, W) Combined With SiO2 Membrane

0.5 mol% Pt decorated SnO₂ (Pt-SnO₂), 0.5 mol% Pd decorated SnO₂ (Pd-SnO₂), 0.5 mol% Pt decorated WO₃ (Pt-WO₃), and 0.5 mol% Pd decorated WO₃ (Pd-WO₃) gas sensing films were fabricated by screen printing. Subsequently, SiO₂ membrane was deposited in situ by CVD. The response of the sensing films to CO, NO, H₂, and NO₂ were investigated. Pt-SnO₂, Pd-SnO₂, and Pt-WO₃ with SiO₂ membrane deposited for 20 min (Pt-WO₃-SiO₂) and Pd-WO₃ showed highly sensitive and selective to CO, NO, H₂, and NO₂ at each optimal operating temperature respectively. Different enhancements of response to target gases might be associated to the combined effects of electronic, chemical sensitizations, and “support effect”. The highly sensitive and selective gas sensors in this paper can be integrated into a gas sensor array to fabricate an electronic nose for H₂, CO, NO, and NO₂ detection