Selective NO₂Sensors Using MoS₂-MoO₂Composite Yolk-shell Spheres

Abstract

Abstract The gas sensing characteristic of MoS 2 -MoO 2 composite yolk-shell spheres were investigated. MoO 3 -carbon compositespheres were prepared by ultrasonic spray pyrolysis of aqueous droplets containing Mo-source and sucrose in nitrogen,which were converted into MoO 3 yolk-shell spheres by heat treatment at 400 o C in air. Subsequently, MoS 2 -MoO 2 compositeyolk-shell spheres were prepared by the partial sulfidation of MoO 3 . The MoS 2 -MoO 2 composite yolk-shell spheres showedrelatively low and irreversible gas sensing characteristics at < 200 o C. In contrast, the sensor showed high and reversibleresponse (S=resistance ratio) to 5 ppm NO 2 (S = 14.8) at 250 o C with low cross-responses (S = 1.17-2.13) to other interferencegases such as ethanol, CO, xylene, toluene, trimethylamine, NH 3 , H 2 , and HCHO. The MoS 2 -MoO 2 composite yolk-shellspheres can be used as reliable sensors to detect NO 2 in a selective manner.Keywords: Gas sensors, MoS 2 Yolk-shell Spheres, NO 2 Sensor, Selectivity