▎ 摘　　要

Mesoporous SnO2 nanospheres are synthesized by template-free solvothermal method, and then reduced graphene oxide (rGO) nanosheets are anchored on SnO2 nanospheres (SnO2@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 & DEG;C for SnO2@0.5%rGO sensor. Owing to the huge surface area and conductivity, rGO nanosheets absorb more oxygen molecules and extract electrons from SnO2 nanospheres, leading to the thicker electron depletion layer of SnO2 nanospheres. Furthermore, p-n heterojunctions at the interface of rGO nanosheets and SnO2 nanospheres further increase the thickness of electron depletion layer. However, SnO2@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.