Aerosol assisted chemical vapor deposition routes for the selective formation of gas sensitive iron oxide structures.

Iron oxide (Fe 2 O 3) structures with various morphologies are synthesized by aerosol-assisted chemical vapor deposition (AACVD) method. The structures are formed reproducibly by tuning different AACVD synthesis parameters, including temperatures, solvents, and samples' position in the reaction chamber. The properties of these structures are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Results demonstrate the formation of six types of crystalline Fe 2 O 3 structures - flattened pyramids (fPy), pyramids (Py), porous pyramids (pPy), sheets (Sh), bricks (Br), and quasi-spherical particles (qsP). The formation of these structures is mainly connected with the use of acetone or acetone/ethanol mixture as solvents and their effect on boosting the influence of the temperature or sample's position, respectively, on the properties of the structures. The gas sensing tests of the structures with higher aspect ratios or porosity (pPy, Py, fPy, and Sh) showed responses to various gases (acetone, ethanol, toluene, carbon monoxide, hydrogen, methane, ammonia, and nitrous oxide), reporting maximum sensitivity and selectivity to acetone and ethanol. The best results recorded are for the porous pyramids which show sensitivities of 5.1 % ppm−1 and 3.9 % ppm−1 (in the range of 10–40 ppm) to acetone and ethanol, respectively. [ABSTRACT FROM AUTHOR]