GS6.1 - Highly selective and sensitive detection of benzene, toluene, and xylene using oxide semiconductors

17th International Meeting on Chemical Sensors - IMCS 2018
2018-07-15 - 2018-07-19
Vienna, Austria
Gas Sensors 6 - Sensing VOCs
J. Lee - Department of Materials Science and Engineering, Korea University, Seoul (South Korea)
235 - 235


Metal oxide semiconductor gas sensors have been widely used to detect ethanol, propane, carbon monoxide, formaldehyde and methane for screening intoxicated drivers and alarming the presence of explosive/dangerous gases. In contrast, the selective and sensitive detection of harmful BTX (Benzene, Xylene, and Toluene) for monitoring indoor/outdoor air pollution using oxide semiconductor chemiresistors remains challenging because of their low reactivity. In this contribution, various new strategies to achieve selective detection of sub-ppm-level BTX gases will be presented. The key ideas are (1) the use of catalytically active sensing materials with tuned nanostructures, (2) synergistic combination of different catalytic materials, (3) the gas reforming of less reactive BTX gas into more active and smaller species using catalyst-loaded micro-reactors, and (4) the tuning of sensing reaction using bilayer sensor design. Various examples for selective and sensitive BTX sensing will be covered, which include Pd-loaded SnO2 yolk-shell micro-reactors, Cr-doped NiO hierarchical nanostructures, Cr-doped Co3O4 nanorods, Pd-loaded Co3O4 hierarchical nanostructures, NiO/NiMoO4 nanocomposite hierarchical spheres, NiO/NiWO4 composite yolk-shell spheres, Cr2O3-ZnCr2O4 hetero-nanostructures, Co3O4 film with SnO2/TiO2 overlayer, and Pd-SnO2 film with Co3O4 overlayer. The main focus will be placed on the elucidation of gas sensing mechanism in relation to the gas reactivity, catalytic activity of sensing/additive materials, gas reforming of analyte gas, and catalytic oxidation of interference gas.