A novel flexible CO2 gas sensor based on polyvinyl alcohol/yttrium oxide nanocomposite films

Polyvinyl alcohol/yttrium oxide (PVA/Y2O3) nanocomposite films with five different weight ratios of PVA and Y2O3 nanoparticles (NPs) were prepared using a simple solution casting method. The prepared polymer nanocomposite (PNC) films were examined using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). FTIR spectra exhibited a strong interaction between the PVA matrix and Y2O3 NPs. SEM results indicated that Y2O3 NPs were properly dispersed in the PVA matrix. The thermal stability of the PVA/Y2O3 nanocomposite films was found to be dependent on Y2O3 NP loading (wt%) in the nanocomposite films. Furthermore, chemiresistive gas sensing properties of the PVA/Y2O3 nanocomposite films were evaluated and the sensing parameters including sensing response, operating temperature, selectivity, stability, response/recovery time, and repeatability were systematically investigated based on the change in electrical resistance of the nanocomposite film in the presence of carbon dioxide (CO2) gas. The maximum sensing response (S) of 92.72% at a concentration of 100 ppm under an optimized operating temperature of 100 °C with a fast response/recovery time of ∼15/11 s towards CO2 gas detection was observed for the PVA/Y2O3 nanocomposite film with 5 wt% loading of Y2O3 NPs in the PVA matrix. The finding in this work suggest that Y2O3 NPs are sufficiently fast as a CO2 gas sensing material at a relatively low operating temperature. Moreover, the key role of the Y2O3 NPs in modulating the electrical and gas sensing properties of the PVA matrix is discussed here.