The impact of Zn vacancy on gas sensitivity of ZnSn(OH)6

Regular octahedral pure ZnSn(OH)6 (ZHS) and ZHS with Zn vacancy (VZn-ZHS) are fabricated with hydrothermal method. The samples are characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The results are as follows: the obtained samples are ZHS, both the left shift of XRD (200) peak and the decline of crystalline can be ascribed to Zn vacancy (VZn); the morphology of the samples is regular octahedron and the surface is covered with steps-like stripes and small holes; the growth orientation of the crystal is [111]; the elements are evenly distributed and there are only Zn, Sn and O elements in the material. The gas sensing experiments show that the sensitivity of VZn-ZHS to 100 ppm triethylamine (TEA) is up to 69.25 at 280 °C under 36% relative humidity (RH), compared to ZHS of 30.84. The theoretical calculation shows that the band gap width and the electric resistance increases with the increase of Zn vacancies (VZn) which is consistent with the experimental results. Meanwhile, VZn can also decrease the work function of ZHS (200) surface, which is the theoretical basis for the improvement of gas sensitivity.