Room temperature NO_2 gas sensor based on PPy/α-Fe_2O_3 hybrid nanocomposites

摘要

Polypyrrole-iron oxide (PPy/α-Fe_2O_3) 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-Fe_2O_3 nanoparticles. The gas-sensing properties of the hybrid nanocomposites were studied and compared with those of PPy and α-Fe_2O_3. It was found that PPy/α-Fe_2O_3 hybrid nanocomposites can complement the drawbacks of pure PPy and α-Fe_2O_3 to some extent. It was revealed that PPy/α-Fe_2O_3 (50%) hybrid sensor operating at room temperature could detect NO_2 at low concentration (10 ppm) with very high selectivity (18% compared to C_2H_5OH) and high sensitivity (56%), with better stability (85%). The sensing mechanism of PPy/α-Fe_2O_3 materials to NO_2 was presumed to be the synergism of PPy and α-Fe_2O_3 or the effect of p-n heterojunctions.