▎ 摘　　要

In this work, a selective chemi-resistive gas sensor of molybdenum diselenide/graphene (MoSe2/G) nanoflakes (NF) that detects ammonia (NH3) and nitrogen dioxide (NO2) gas at room temperature is successfully fabricated. The MoSe2/G NF based sensor shows good sensitivity (2.476 ppm(-1)) and selectivity to NO2 in comparison with some VOCs and toxic gases than MoSe2 NF (2.275 ppm(-1)). But in case of NH3 gas, it shows a drastic increase in sensitivity of MoSe2/G NF (9.115 ppm(-1)) than MoSe2 NF (2.466 ppm(-1)). The MoSe2/G NF shows a low detection limit (11 ppb for NH3 and 41 ppb for NO2), an outstanding repeatability, and a reliable long-term device durability (more than eight weeks) significantly. The reason of the significant improvement in gas sensing performance can be attributed mainly due to the addition of graphene in MoSe2 NF which in turns increases the surface-to-volume ratio. It encourages the adsorption of gas molecules on the surface of the material, thereby facilitating the charge transfer process. The superior performance of this gas sensor makes MoSe2/G NF a potential candidate for NO2 and NH3 gas detection at room temperature. Due to the presence of graphene, MoSe2 NF becomes less hydrophilic which shows very less effect of humidity effect.