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.