Butanone Sensing Characteristics, Mechanism and Equivalent Circuit Model of Pd Decorated ZnO Nanorod Based Resistive Sensors

摘要

Zinc oxide (ZnO) nanorods, both unmodified and modified by palladium (Pd) nanoparticles, were prepared via a low temperature chemical bath deposition technique using a sol-gel grown ZnO seed layer on SiO_2 substrate. The surface morphology and crystallinity of the thin film was characterized by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). The Pd modified ZnO nanorods with Pd-Ag catalytic contact were tested for 2-butanone vapor detection in the resistive mode and was found to offer high response magnitude (86%) at moderately lower temperature (～ 190℃). On the other hand, the sensors with as deposited ZnO (with Pd-Ag or Au contact) offered much lower response magnitude (82% and 66%). Surface modification of nanorods by Pd nanoparticles contributed towards improving response time and recovery time for both type of electrodes within the dynamic range of ～ 190-1530 ppm. Finally, the possible mechanism of the 2-butanone vapor sensing has been discussed elaborately invoking the corresponding energy band diagram and equivalent circuit model.