MoS2/multiwalled carbon nanotubes based composite for room-temperature ammonia sensing

In past few years, two-dimensional transition metal dichalcogenides (TMDCs) with general formula MX2, where M is a transition metal (Mo, W or Ti) and X is a chalcogen (S, Se or Te) atom, have attracted significant attention in gas sensing applications due to their layered structure, semiconducting properties and superior responsivity at room-temperature. Multiwalled carbon nanotubes (MWCNT), on the other hand, have been used to enhance the gas sensing response of a base material. Herein, we report sensitive, selective and improved detection of ammonia by MoS2/MWCNTs composite as compared to MoS2 based two-terminal devices at room-temperature. A facile hydrothermal route was used to prepare MoS2/ MWCNTs composite. An alumina substrate with pre-deposited gold contacts was used to make twoterminal devices. The resulting two-terminal devices have shown n-type semiconducting nature and high sensitivity/selectivity towards ammonia when compared with other reducing gases like hydrogen sulfide, formaldehyde and ethanol. Further, the composite based device shows faster response and recovery features compared to MoS2 and lower detection limit down to 10 ppm. Raman spectra from the sample indicated the presence of various Raman modes corresponding to vibrations of various atoms in MoS2 and D, G bands belonging to MWCNTs. Present results suggest that MoS2/MWCNTs composite can be employed for improved and selective ammonia gas monitoring at room-temperature. (c) 2021 Elsevier Ltd. All rights reserved. Second International Conference on Aspects of Materials Science and Engineering (ICAMSE 2021).