Sensitive NO2 sensor based on silver nanowires-decorated monolayer graphene with assistance of UV illumination

In this study, a gas sensor consisting of Ag nanowires (Ag NWs) dispersed on surface of monolayer graphene was prepared by spray coating. The sensing performance was investigated in terms of response sensitivity and recovery speed at room temperature with the assistance of UV illumination. The correlation between initial volume of Ag NWs solution and final coverage of Ag NWs was built. A series of systematical sensing tests indicated the sensing performance was greatly dependent on the coverage of Ag NWs, and the sensor consisted of 4.8% Ag NWs coverage exhibited highest response upon NO2 exposure. Raman spectrum revealed electron-donor role of Ag NWs, which facilitates adsorption of NO2 on graphene resulting in a doubled response compared to that of bare graphene (40% for 5 ppm of NO2). In addition, with photoexcitation using UV illumination, the sensor exhibited recovery time of 4 min, which was much faster than that of exposure to NO2 without UV illumination (15 min at the same concentration of NO2). This approach appeared to be highly practical to overcome the problematic low recovery speed of graphene-based sensors.

Automated summary

In this study, a gas sensor with Ag nanowires dispersed on graphene was prepared by spray coating. The sensing performance was evaluated in terms of sensitivity and recovery speed at room temperature with UV illumination. The coverage of Ag nanowires greatly influenced the sensing performance, with a coverage of 4.8% exhibiting the highest response to NO2 exposure.