Electrospinning preparation of Pd@Co3O4-ZnO composite nanofibers and their highly enhanced VOC sensing properties

In this paper, pure ZnO, Co3O4-ZnO, Pd@ZnO and Pd@Co3O4-ZnO composite nanofibers were synthesized by electrospinning method. Multiple characterizations were employed to investigate the crystal structure, composition, morphology, and bonding states of the Pd@Co3O4-ZnO composite nanofibers. The sensing properties of the as -synthesized nanofibers were evaluated toward different volatile organic components (VOCs) including ethanol, acetone, isopropanol and formaldehyde under the various operating temperatures. The obtained results have clearly demonstrated that the Pd@Co3O4-ZnO composite nanofibers exhibits significantly enhanced VOC sensing performance compared with other nanofibers. Specifically, the response of Pd@Co3O4-ZnO composite nanofibers toward 200 ppm ethanol is 59 at 240 degrees C, which is much higher than that of ZnO nanofibers. The enhanced VOC sensing properties of Pd@Co3O4-ZnO composite nanofibers could be attributed to the electronic and chemical sensitizations of Pd and the p-n junction formation at the interface of Co3O4 and ZnO