UV light irradiation enhanced gas sensor selectivity of NO2 and SO2 using rGO functionalized with hollow SnO2 nanofibers

Herein, to enhance selective detection of NO2 and SO2 using a single device, an ultraviolet (UV) light activated gas sensor has been reported based on reduced graphene oxide (rGO) functionalized with hollow SnO2 nanofibers (NFs) at room temperature. The porous hollow SnO2 NFs are synthesized using electrospinning and calcination treatment, then different contents of SnO2 are introduced to rGO for preparation of rGO/SnO2 nanocomposites by facile magnetic stirring and ultrasonic treatment. The rGO/SnO2 samples reveal obvious sensing response, great reversibility and good humidity resistance to target gases at ppm level. Under different intensities of UV light illumination, gas sensing properties of rGO/SnO2 are studied to explore the photoexcited sensing behaviors. The greatly enhanced selective detection to NO2 (102%) and SO2 (11%) is achieved with a response ratio of 9.3 by using UV light illumination. The results show sensor response and selectivity can be improved using appropriate intensity of excitation light, demonstrating significant modulation effect of UV light assistance on gas detection. The mechanism may be attributed to light motivated electron-hole pairs due to built-in electric fields under UV light illumination, which can be captured by target gases and lead to UV controlled gas sensing performance.