Highly sensitive and rapidly responding room-temperature NO2 gas sensors based on WO3 nanorods/sulfonated graphene nanocomposites

Metal oxide/graphene nanocomposites are emerging as promising materials for developing room-temperature gas sensors. However, the unsatisfactory performances owing to the relatively low sensitivity, slow response, and recovery kinetics limit their applications. Herein, a highly sensitive and rapidly responding room-temperature NO 2 gas sensor based on WO 3 nanorods/sulfonated reduced graphene oxide (S-rGO) was prepared via a simple and cost-effective hydrothermal method. The optimal sensor response of the WO 3 /S-rGO sensor toward 20 ppm NO 2 is 149% in 6 s, which is 4.7 times higher and 100 times faster than that of the corresponding WO 3 /rGO sensors. In addition, the sensor exhibits excellent reproducibility, selectivity, and extremely fast recovery kinetics. The mechanism of the WO 3 /S-rGO nanocomposite gas sensor is investigated in detail. In addition to the high transport capability of S-rGO as well as its excellent NO 2 adsorption ability, the superior sensing performance of the S-rGO/WO 3 sensor can be attributed to the favorable charge transfer occurring at the S-rGO/WO 3 interfaces. We believe that the strategy of compositing a metal oxide with functionalized graphene provides a new insight for the future development of room-temperature gas sensors.