Selective room-temperature ammonia sensing using CeO 2 -multiwalled carbon nanotube composite

A chemiresistive sensor has been developed for the room-temperature detection of ammonia vapors using CeO 2 /multiwalled carbon nanotubes composite synthesized via. two-step method. Structural analysis has revealed the successful formation of the composite. The ammonia sensing measurements using composite-based sensor have shown an increase in device resistance when exposed to ammonia vapors. This indicates p-type conduction in the composite. A linear relation between sensing response and ammonia concentration was obtained. On the one hand, sensor made from CeO 2 also gave a sensing response at room temperature and corresponding recovery time was quiet large (190 s). On the other hand, sensor made from CeO 2 /MWCNTs has shown a response time of 35 s and relatively smaller recovery time (100 s). Further, composite-based sensor has shown higher sensitivity to ammonia when compared with dimethyl formamide, N-methyl pyrrolidone, methanol, isopropyl alcohol, ethanol and chloroform. Importantly, the device has shown a stable and reproducible characteristics over a wide range of humidity.