Non-stoichiometric Mn-oxides (MnO x and MnO y) were prepared by temperature-programmed oxidation (TPO) of Mn-oxalates, MnC 2O 4·3H 2O and MnC 2O 4·2H 2O. Both oxides provide high specific surface areas (525 m 2 g -1 and 385 m 2 g -1, respectively) and identical CO oxidation reaction rates of 10 -2 molecules nm -2 s -1 (0.017 μmol CO m -2 s -1) at 298 K. A "spinodal" transformation of oxalates into oxides was observed by transmission electron microscopy (TEM). The quantitative evaluation of TPO and temperature-programmed reduction with CO allowed x-values of 1.61, ⋯, 1.67 to be determined for MnO x. The Mn oxidation state in MnO x was found to be 3.4 ± 0.1 by X-ray absorption near-edge structure analysis and X-ray photoelectron spectroscopy. In accordance with the high specific surface area and mixed-type I/IV adsorption isotherms of MnO x, high resolution TEM demonstrated the occurrence of nested micro-rod features along with nanocrystalline particles in the endings of the rods. After CO oxidation MnO and Mn 3O 4 phases were able to be identified in the regions between rods.
- CO oxidation
- Manganese oxide
- Micro-rods and nanocrystals
ASJC Scopus subject areas
- Physical and Theoretical Chemistry