Ultrahigh-performance impedance humidity sensor based on layer-by-layer self-assembled tin disulfide/titanium dioxide nanohybrid film

An ultrahigh-performance impedance-type humidity sensor based on tin disulfide (SnS2)/titanium dioxide (TiO2) nanocomposite was demonstrated via layer-by-layer self-assembly technique in this work. The nanostructures, morphologies, composition properties of the SnS2/TiO2 nanocomposite were fully examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The humidity sensing characteristics of the SnS2/TiO2 film sensor were investigated at room temperature. The results show that the SnS2/TiO2 film sensor has an impedance response up to 200050 and a sensitivity of 442000 Ω/%RH, which is much better than that of the existing humidity sensors. Excellent stability and repeatability are also exhibited for the SnS2/TiO2 film sensor. Moreover, the underlying sensing mechanism for the SnS2/TiO2 sensor toward humidity was explored with the complex impedance spectroscopy and the Bode diagram. The SnS2/TiO2 nanocomposite provides a promising building block for ultrahigh-sensitive humidity sensing and detection of human respiratory.