SnO2/Co3O4 nanofibers (NFs) are synthesized by using a homopolar electrospinning system with double jets of positive polarity electric fields.The morphology and structure of SNO2/Co3O4 hetero-nanofibers are characterized by using field emission scanning electron microscope (FE-SEM),transmission electron microscope (TEM),x-ray diffraction (XRD),and x-ray photoelectron spectrometer (XPS).The analyses of SnO2/Co3O4 NFs by EDS and HRTEM show that the cobalt and tin exist on one nanofiber,which is related to the homopolar electrospinning and the crystallization during sintering.As a typical n-type semiconductor,SnO2 has the disadvantages of high optimal operating temperature and poor reproducibility.Comparing with SnO2,the optimal operating temperature of SnO2/Co3O4 NFs is reduced from 350 ℃ to 250 ℃,which may be related to the catalysis of Co3O4.The response of SnO2/Co3O4 to 100-ppm ethanol at 250 ℃ is 50.9,9 times higher than that of pure SnO2,which may be attributed to the p-n heterojunction between the n-type SnO2 crystalline grain and the p-type Co3O4 crystalline grain.The nanoscale p-n heterojunction promotes the electron migration and forms an interface barrier.The synergy effects between SnO2 and Co3O4,the crystalline grain p-n heterojunction,the existence of nanofibers and the large specific surface area all jointly contribute to the improved gas sensing performance.