Chemical Vapor Synthesis and Characterization of Manganese Oxides

Manganese oxide nanoparticles are synthesized by a chemical vapor process using manganese(0) carbonyl as the precursor. The synthesis temperature of the materials is varied from 500 to 1500 degrees C at 200 degrees C intervals. These nanomaterials are characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, and X-ray photoelectron spectroscopy (XPS). XRD shows that the manganese oxide nanoparticles synthesized at 500, 700 - 1100, 1300, and 1500 degrees C are mainly MnO(2), Mn(2)O(3), Mn(2)O(3)/Mn(3)O(4), and Mn(3)O(4), respectively. The TEM and BET results also confirm that the particle size is on the nanometer scale with a large specific surface area (SSA) of 81 - 215m(2) g(-1). XPS indicates the catalysts to have manganese oxidation states of (2+), (3+), or (4+) depending on the synthesis temperature.