Ultrasensitive NO2 gas sensing based on rGO/MoS2 nanocomposite film at low temperature

In this paper, both reduced graphene oxide (rGO) and rGO/molybdenum disulfide (MoS2) composite films serving as sensing layers were prepared for nitrogen dioxide (NO2) gas detection at low operation temperature, wherein multiple characterization techniques containing TEM, XRD, XPS and Raman were employed. The experimental results showed that rGO/MoS2 composite film possessed a larger exposure area, more sorption sites and a mass of p -n heterojunctions, thereby resulting in a sensing response of 59.8% toward 2 ppm NO2 at 60 C (optimal operation temperature), which was nearly 200% enhanced in comparison with bare rGO one. Furthermore, we investigated the role of rGO or MoS2 material in the sensing performance as well as the effect of different MoS2 introduction manners. Apart from these, relative humidity was found to pose a small interfering impact on NO2 response, while long-term stability on exposure to 120 ppb NO2 revealed a small response decay after several weeks. Moreover, the composites showed an excellent selectivity toward NO2 gas against other interfering gas species. Through further exploration of ppb-level NO2 detection, the detection limit was calculated to be as low as 5.7 ppb. (C) 2017 Elsevier B.V. All rights reserved.