P2GS.8 - Highly Selective and Sensitive Detection of Methylbenzenes via Concurrent Control of the Gas Reforming and Filtering in Catalytic Oxide Overlayer

17th International Meeting on Chemical Sensors - IMCS 2018
2018-07-15 - 2018-07-19
Vienna, Austria
P-2 - Gas Sensors
J. Kim, H. Jeong, J. Kim, B. Kim, J. Lee - Department of Materials Science and Engineering, Korea University, Seoul (Republic of Korea), H. Jang - 2Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul (Republic of Korea)
785 - 785


A Co3O4 gas sensor coated with catalytic oxide overlayer was fabricated by screen printing of Co3O4 yolk-shell spheres on the substrate and subsequent deposition of SnO2 or TiO2 catalytic overlayer by e-beam evaporation. Co3O4 gas sensors with TiO2 and SnO2 overlayer (thickness: 5 nm) showed high responses (resistance ratios) to 5 ppm xylene (14.5, 28.8) and 5 ppm toluene (11.7, 16.2) at 250 C and exhibited excellent selectivity against other interfering gases such as ethanol, HCHO, CO, and benzene. In contrast, the pure Co3O4 gas sensor did not show high selectivity toward any specific gas. The excellent selectivity to methylbenzenes was attributed to catalytic reforming of less reactive methylbenzene into more reactive and smaller species and catalytic oxidation of reactive interference gases such as ethanol and HCHO at catalytic overlayer. These concurrent tuning of the gas reforming and oxidative filtering processes using a nanoscale catalytic oxide overlayer provides a new, general, and effective method for fabricating highly selective and sensitive metal oxide semiconductor gas sensors.