Zhou F. Y.,Xu J. C.,Hong B.,Peng X. L.,Zeng Y. X.,Li J.,Ge H. L.,Wang X. Q.
Mesoporous SnO 2 nanospheres are synthesized by template-free solvothermal method, and then reduced graphene oxide (rGO) nanosheets are anchored on SnO 2 nanospheres (SnO 2 @rGO nanocomposites) by hydrothermal method. The gas-sensing results indicate that rGO nanosheets greatly affect the formaldehyde (HCHO) gas-sensing properties, which the response to 100 ppm HCHO gas increases with the rGO content and reach the maximum of 113.56 at 190 °C for SnO 2 @0.5%rGO sensor. Owing to the huge surface area and conductivity, rGO nanosheets absorb more oxygen molecules and extract electrons from SnO 2 nanospheres, leading to the thicker electron depletion layer of SnO 2 nanospheres. Furthermore, p-n heterojunctions at the interface of rGO nanosheets and SnO 2 nanospheres further increase the thickness of electron depletion layer. However, SnO 2 @0.8%rGO sensor presents the lower response for the new conductive pathways between the surface rGO nanosheets due to the excess of rGO content.
Graphical abstract
Porous SnO2 nanospheres with high surface areas have been synthesized through a solvothermal method in the absence of any templates. The structure and morphology of the resultant products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption–desorption technique. The as-prepared SnO2 porous nanospheres with the diameters ranging from 90–150 nm are composed of small nanocrystals with average sizes of less than 10 nm. Results demonstrated that the formation of porous SnO2 nanospheres is ascribed to etching the center part of the nanospheres. It was found that hydrochloric acid and NaClO played important roles in determining the final morphologies of the porous SnO2 nanospheres. The gas sensing properties of the as-prepared porous SnO2 nanospheres were investigated. By the comparative gas sensing tests, the porous SnO2 nanospheres exhibited a superior gas sensing performance toward ppb level 2-chloroethanol and formaldehyde vapor, implying promising applications in detecting toxic volatile organic compounds (VOCs).
危险品化学品经营许可证（带存储）