Enhancement of sensitivity and selectivity of α-Fe2O3 nanorod gas sensors by ZnO nanoparticles decoration

The iron oxide nanorods synthesized and decorated with zinc oxide nanoparticles by using hydrothermal method. Spray pyrolysis method was applied to deposit thin films. The morphology and structure of the samples investigated by x-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and fourier-transform infrared spectroscopy (FTIR). The samples were exposed to the vicinity of several toxic gases/alcoholic vapors in the temperature range of 50-300 degrees C and their electrical responses were collected. Approximately 59% response enhancement was achieved for ZnO-decorated alpha-Fe2O3 nanorod samples along with faster response-rate compared to the pure alpha-Fe2O3 nanorods. Results from this study also showed that the decorated ZnO on the alpha-Fe2O3 nanorods exhibited higher sensitivity to H2S gas relative to the other gaseous mixture constituents obtained at 200 degrees C. After exposing the sensor to the target gas molecules, the resistivity decreased compared to the pure alpha-Fe2O3 and ZnO sensor likely due to the existence of various depletion layers on the surface.