Oxygen vacancy engineering for enhanced sensing performances: A case of SnO2 nanoparticles-reduced graphene oxide hybrids for ultrasensitive ppb-level room-temperature NO2 sensing

In this paper, SnO 2 nanoparticles (NPs) decorated reduced graphene oxide hybrids with abundant vacancies (designated as SnO 2 -RGO-OVs) have been successfully prepared by a combined hydrothermal synthesis and chemical solution deposition method. It is found that high density SnO 2 NPs with the size of 3–5 nm are uniformly distributed on the surface of RGO nanosheets. Most importantly, SnO 2 -RGO-OVs hybrids exhibit excellent room-temperature NO 2 sensing properties with the low detection limit of 50 ppb. When SnO 2 -RGO-OVs-based sensor was exposed to 1 ppm NO 2 , the response is 3.80 and response time and recovery time are 14 s and 190 s, respectively. These sensing performances are superior to those of most reported room-temperature NO 2 sensors based on RGO-based materials and other materials. The excellent sensing performances of SnO 2 -RGO-OVs hybrids can be attributed to their specific structure, e.g., RGO that could facilitate transferring carriers during sensing progress, and abundant OVs that could facilitate adsorption of more NO 2 molecules onto SnO 2 NPs in SnO 2 -RGO-OVs hybrids.