Ethanol sensing properties of γ-Fe2O3 nanopowder doped with Mg by nonaqueous medium method

In this study, undoped and Mg-doped γ-Fe2O3 nanopowders have been synthesized by nonaqueous medium method and studied for their gas sensing behavior to C2H5OH, CH4, NH3, H2 and CO. Thermo-gravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometer (ICPOES) and transmission electron micrograph (TEM) were employed to characterize the composition, phase and particle size of the products. XRD data show that the Mg is dissolved into the material and acts as nanocrystalline grain inhibitor in the case. Well-formed nanocrystalline particles, essential to good gas sensing properties, are observed by TEM and HRTEM. The results suggest that the γ-Fe2O3 gas sensor doped with 30 mol% Mg presents high sensitivity to C2H5OH but low sensitivity to CH4, NH3, H2 and CO at the operating temperature of 270 °C. Compared with the undoped, the improvement in the gas sensing performance, such as high sensitivity, selectivity and quick response, is mainly attributed to the nature of Mg addition. Besides, the relative mechanism is also discussed in detail.