UV Light Assisted NO2Sensing by SnO2/Graphene Oxide Composite

Nitric oxide (NO2) is one of the air pollutants that pose serious environmental concerns over the years. In this study, SnO2 nanowires were synthesized by evaporation-condensation method and graphene oxide were synthesized using modified Hummers method for low temperature NO2 detection. Drop cast method was used to transfer graphene oxide (GO), to form composite GO-metal oxide p-n junctions. With integration of reduce graphene oxide (rGO), the UV light absorption was enhanced. This metal oxide composite has shown a reversible response in detecting low concentrations of NO2 under UV irradiation, with a working temperature range of 50–150 °C. Pure SnO2 shows 20% response to NO2 (4 ppm) in dark conditions, while the response increasesupto60%usingUVirradiationat50°C.Furthermore, SnO2/rGOshowsa40%ofresponse in dark, while the response increases to 160% under UV light illumination. This composite exhibits excellent recovery and maintains the baseline under UV light at low temperatures, which effectively overcome the drawbacks of low recovery typically shown by metal oxide gas sensors at low temperature.