Polyaniline-Magnesium Oxide Nanocomposites: Synthesis, Characterization, and Optimized LPG Sensing at Room Temperature

In this work, pure Polyaniline (PANI) and PANI–Magnesium Oxide (PANI/MgO) nanocomposites with varying MgO content (10–40 wt%) were successfully synthesized via in situ polymerization. Comprehensive characterization was performed to investigate their structural, morphological, optical, thermal, electrical, and LPG gas sensing properties. X-ray diffraction confirmed the nanocrystalline nature of MgO (34.92 nm) and an increased crystallite size (48.06 nm) in the composite, indicating strong interaction between the components. Scanning electron microscopy revealed a uniform spherical morphology, while Fourier-transform infrared spectroscopy showed band shifts suggesting chemical interaction between PANI and MgO. Optical analysis via UV–vis spectroscopy exhibited characteristic absorption peaks at 274 and 357 nm, with corresponding optical band gap calculations. Thermogravimetric analysis demonstrated improved thermal stability in the composites compared to pure PANI. Electrical measurements using a precision impedance analyzer revealed that the dielectric constant remained stable at high frequencies, while AC conductivity increased with MgO content. Notably, LPG sensing studies indicated that the PANI/MgO (40 wt%) nanocomposite achieved the highest sensitivity of 70% at 25,000 ppmv, with a fast response (40 s) and recovery time (51 s). These results highlight the potential of PANI/MgO nanocomposites as efficient, thermally stable materials for advanced gas sensing applications.