Preparation And NO₂ Gas Sensing Performance Study On WO₃/sulfonated Graphene Composite Materiats

Nitrogen dioxide（NO₂）is one of the most common and dangerous air pollutants and an exposure to few ppm is hazardous in terms of both health risk and environmental damage.It is commonly found or generated from domestic heat burners,exhaust gases of automobiles,combustion of fossil fuel,chemical factories,food processing plants,and power plants.Therefore,for the protection of the environment and human health,there is an urgent need for the development of highly sensitive,selective,and rapid response NO₂ gas sensing devices.However,there are still significant challenges for NO₂ sensing at room temperature.To date,the metal oxide/graphene nanocomposites are emerging as one of the promising candidate materials for developing room temperature gas sensors,but these sensors still have more or less disadvantages,such as low sensitivity,slow response and they need a long time to recover to the initial value.Herein,a highly sensitive and fast responding room-temperature NO₂ gas sensor based on WO₃ nanorods /sulfonated reduced graphene oxide（S-r GO）was prepared via a simple and cost-effective hydrothermal method.By introducing the sulfonate acid into rGO,the S-r GO exhibits much better conductivity and dispersing ability than that of r GO.The optimal sensor response of WO₃/S-rGO toward 20 ppm of NO₂ is 149% in 6 s,which is 4.7 times higher and 100 times faster than that of the corresponding WO₃/r GO sensors.In addition,it also exhibits excellent reproducibility,selectivity,and extremely fast recovery kinetics.That proves such impressive features originate from the introduction of S-rGO into the composites.This work may open up new possibilities for further improvement of metal oxide/ functionalized graphene nanocomposites with even higher sensing performances,additionally,it offers guidance for the material design to develop new room temperature sensors.