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

•Hollow ZnO–SnO2 core–shell nanofibers are fabricated via two-step process. First, hollow SnO2 nanofibers are synthesized by electrospinning. Second, the ZnO shell is grown on the fibers via the hydrothermal method.•The ZnO–SnO2 sensor exhibits a dramatic improvement in ethanol sensing performance at 200 °C.

Designingcomposite 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–SnO2 heterostructure is reported. The hollow SnO2 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–SnO2 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–SnO2 sensor is 392.29, which is 11 times larger than that of SnO2 sensor (about 35.02). The response and recovery time of ZnO–SnO2 sensor are 75 s and 12 s, while that of SnO2 sensor are 86 s and 14 s, respectively. The results reveal that ZnO–SnO2 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–SnO2 heterojunction and the ethanol sensing mechanism are analyzed.

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