Room temperature NO2 gas sensor based on PPy/α-Fe2O3 hybrid nanocomposites

Polypyrrole–iron oxide (PPy/α-Fe2O3) hybrid nanocomposite sensor films were prepared by spin coating method on glass substrate and characterized for structural and morphological properties by means of X-ray diffraction (XRD), Fourier transform infra red (FTIR) spectroscopy and scanning electron microscopy (SEM), which proved the strong interaction between polypyrrole and α-Fe2O3 nanoparticles. The gas-sensing properties of the hybrid nanocomposites were studied and compared with those of PPy and α-Fe2O3. It was found that PPy/α-Fe2O3 hybrid nanocomposites can complement the drawbacks of pure PPy and α-Fe2O3 to some extent. It was revealed that PPy/α-Fe2O3 (50%) hybrid sensor operating at room temperature could detect NO2 at low concentration (10 ppm) with very high selectivity (18% compared to C2H5OH) and high sensitivity (56%), with better stability (85%). The sensing mechanism of PPy/α-Fe2O3 materials to NO2 was presumed to be the synergism of PPy and α-Fe2O3 or the effect of p–n heterojunctions.