Layer-by-layer self-assembly of tricobalt tetroxide-polymer nanocomposite toward high-performance humidity-sensing

In this paper, a humidity sensor with tricobalt tetroxide (Co3O4)/poly(sodium styrene sulfonate) (PSS) film coated was fabricated using layer-by-layer (LbL) nano self-assembly method. The nanostructural, surface morphology and the specific surface area of the LbL self-assembled Co3O4/PSS nanocomposite were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen sorption analysis and transmission electron microscopy (TEM) measurements. The humidity sensing properties of the sensor were investigated by exposing to a wide relative humidity range of 11-97% at room temperature. The experimental results indicate that the presented sensor not only exhibited favorable response of up to 2479.97, but also possessed fast response and recovery time, acceptable repeatability and stability. The sensing performance was greatly better than that of pure Co3O4. Moreover, the possible humidity sensing mechanism can ascribed to the synergistic effect of Co3O4 and PSS toward water molecules, as well as the layered nanostructure. This work highlights the LbL self-assembled Co3O4/PSS film is a candidate material for constructing humidity sensors with high performance for various applications.