Enhanced ethanol sensing performance of hollow ZnO–SnO2 core–shell nanofibers

TLDR: In this paper, a design of the ethanol sensor based on ZnO-SnO 2 heterostructure is reported, and the performance of the fabricated sensors is systematically investigated, which reveal that the hollow shell structure enhances the sensing performance and shortens the response and recovery time.

Abstract: Designing composite nanomaterials is one of the most important key techniques for improving gas sensing performance. In this paper, a design of the ethanol sensor based on ZnO–SnO 2 heterostructure is reported. The hollow SnO 2 nanofibers are first synthesized by using the electrospinning method, and then the ZnO shell is subsequently grown on the fibers via the hydrothermal method. The ZnO–SnO 2 core–shell structure is confirmed by X-ray diffraction (XRD), energy dispersive spectrometer (EDS), scanning electron microcopy (SEM), transmission electron microscopy (TEM) and elemental mapping analysis. The gas sensing behaviors of the fabricated sensors are systematically investigated. Under optimum operating temperature (200 °C) at 100 ppm ethanol, the response of ZnO–SnO 2 sensor is 392.29, which is 11 times larger than that of SnO 2 sensor (about 35.02). The response and recovery time of ZnO–SnO 2 sensor are 75 s and 12 s, while that of SnO 2 sensor are 86 s and 14 s, respectively. The results reveal that ZnO–SnO 2 core–shell structure enhances the sensing performance and shortens the response/recovery time, which is attributed to unique hollow structure, oxygen vacancies and n–n heterojunction. In addition, the energy band structure of ZnO–SnO 2 heterojunction and the ethanol sensing mechanism are analyzed.