Effects of graphene on the microstructures of SnO2@rGO nanocomposites and their formaldehyde-sensing performance

Performance modulation of formaldehyde (HCHO) sensing active nanomaterials is of great significance in environmental monitoring and disease diagnosis. This paper reports a simple but robust solvothermal process to synthesize SnO2@rGO nanocomposites for HCHO sensors with rGO mass fractions of 0-2%. The phases, chemical compositions, microstructures and surface states of the as-obtained SnO2@rGO nanocomposites are well characterized. The results indicate that the addition of GO overcomes the agglomeration of SnO2 nanocrystals (35 nm) and highly enhances the specific surface area (SSA) of the SnO2@rGO nanocomposites, leading to higher response and lower operating temperature in the HCHO-sensing application. The SSA of SnO2@rGO is 133.1 m(2)/g, much larger than that (58.3 m(2)/g) of pure SnO2 nanocrystals. The SnO2@rGO nanocomposites exhibit highly selective and sensitive to HCHO vapors at a relatively low operating temperature range of 100200 degrees C. The amount of GO added has a key effect on the HCHO-sensing performance, and the sample of SnO2@rGO-0.5% exhibits the highest response at 100 160 degrees C. Their recovery/response times are shorter than 20 s to HCHO vapors (less than 25 ppm). The enhanced HCHO-sensing performance is attributed to the formation of porous SnO2@rGO nanostructures with high SSAs and suitable electron transfer channels. (C) 2018 Elsevier B.V. All rights reserved.