Polypyrrole (PPy) and polypyrrole/cerium oxide nanocomposite (PPy/CeO₂) were prepared by the chemical oxidative method in an aqueous medium using anhydrous ferric chloride (FeCl₃) as an oxidant. The successful formulation of materials was confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmittance electron microscopy (TEM). A four-in-line probe device was used for studying DC electrical conductivity and ammonia vapor sensing properties of PPy and PPy/CeO₂. The significant improvement in both the conductivity and sensing parameters of PPy/CeO₂ compared to pristine PPy reveals some synergistic/electronic interaction between PPy and cerium oxide nanoparticles (CeO₂ NPs) working at molecular levels. The initial conductivity (i.e., conductivity at room temperature) was found to be 0.152 Scm⁻¹ and 1.295 Scm⁻¹ for PPy and PPy/CeO₂, respectively. Also, PPy/CeO₂ showed much better conductivity retention than pristine PPy under both the isothermal and cyclic ageing conditions. Ammonia vapor sensing was carried out at different concentration (0.01, 0.03, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 vol %). The sensing response of PPy/CeO₂ varied with varying concentrations. At 0.5 vol % ammonia concentration, the % sensing response of PPy and PPy/CeO₂ sensor was found to be 39.1% and 93.4%, respectively. The sensing efficiency of the PPy/CeO₂ sensor was also evaluated at 0.4. 0.3, 0.2, 0.1, 0.05, 0.03, and 0.01 vol % ammonia concentration in terms of % sensing response, response/recovery time, reversibility, selectivity as well as stability at room temperature.

The chemical stability of PVC-based Neodymium phosphate (NP) ion-exchange membrane shows better results with strong oxidizing agent KMnO₄ as compared to the acidic and alkaline medium and it was synthesized by sol–gel and die casting method. The characterization of the ion-exchange composite membrane was carried out by employing Fourier transform infrared spectroscopy, thermogravimetry analysis and scanning electron microscopy. The membrane with 25% PVC and 75% NP shows excellent mechanical and thermal stability as well as good ion-exchange capacity. The observed membrane potential data were used to determine the transport number of cation and anion and other electrochemical parameters of the composite membrane. The prepared membrane can be considered as an excellent material for desalination and wastewater treatment applications.