Enhanced Room-temperature Ammonia Sensing Performance of PANI@ZnO/Fe₃O₄Hybrid Nanocomposites Synthesized via Chemical Oxidative Polymerization

Abstract

Hybrid organic–inorganic nanocomposites have attracted considerable attention owing to their enhanced sensitivity toward oxidizing and reducing gases and their potential for sustainable sensing technologies. In this study, a novel PANI@ZnO/Fe₃O₄ hybrid nanocomposite film was synthesized through chemical oxidative polymerization for high-performance ammonia sensing under ambient conditions. The incorporation of ZnO and Fe₃O₄ nanoparticles into the PANI matrix resulted in measurable changes in the structural, optical, and thermal characteristics of the hybrid nanocomposite. The successful formation of the hybrid nanocomposite was confirmed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, and thermogravimetric analysis (TGA). The optical band gap decreased from 3.18 eV for pure PANI to 2.79 eV for the PANI@ZnO/Fe₃O₄-5 nanocomposite, indicating improved charge transfer characteristics. Among the fabricated sensors, the PANI@ZnO/Fe₃O₄-5 sensor exhibited the highest sensing response of approximately 215% toward 300 ppm NH₃, with a sensitivity of 0.727 % ppm⁻¹ (R² = 0.9989) over the investigated concentration range of 50–300 ppm and rapid response and recovery times of about 11 s. The sensor also demonstrated excellent selectivity against interfering gases, including CO, CO₂, H₂S, and ethanol, together with good long-term stability and humidity tolerance. The enhanced sensing performance may be associated with interactions among PANI, ZnO, and Fe₃O₄ nanoparticles and the resulting changes in the sensing behavior toward NH₃. These findings demonstrate the potential of PANI@ZnO/Fe₃O₄ hybrid nanocomposites as sustainable materials for advanced environmental monitoring and room-temperature ammonia sensing applications.