Enhanced LPG sensing-performance at room temperature of poly(o-anisidine)–CeO2 nanocomposites

Abstract

We report a fast-responding and selective room temperature liquefied petroleum gas (LPG) sensor based on poly(o-anisidine)–cerium oxide (POA–CeO₂) nanocomposites. The POA–CeO₂ nanocomposites were prepared by an in situ chemical oxidative polymerization of o-anisidine in the presence of pre-prepared CeO₂ nanoparticles (size ∼5–10 nm). The pre-prepared CeO₂ nanoparticles were synthesized by a simple and rapid microwave-assisted method. The POA, CeO₂ nanoparticles and their nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The results of the characterization revealed that interaction occurred between the POA and CeO₂ nanoparticles, leading to the formation of POA–CeO₂ nanocomposites. The LPG sensing-performance of the nanocomposites was investigated and compared with that of sensors based on POA. The sensor based on a POA–CeO₂ nanocomposite with known weight percentage of CeO₂ showed better LPG sensing properties than that of pure POA. Upon exposure to 3.4% LPG, the nanocomposite with 30 wt% CeO₂ exhibited an enhanced response (∼2.06%), very fast response (∼3–4 s), full recovery within 20 s in air and, most notably, better selectivity at room temperature. Furthermore, the lower detection limit was ∼0.09% which is lower than the permissible explosive limit for LPG. The reproducibility and stability study reveals that these nanocomposites are highly stable. Thus, the combination of the CeO₂ nanoparticles and POA offers an attractive selective sensing-performance for LPG at room temperature with fast response/recovery rate.