Spinel-type MgMn2O4 nanocrystals represent a promising semiconductor with applications in energy storage as cathode materials for magnesium rechargeable batteries. Presently, thermolysis of complex organic precursors in high boiling point solvents represent the most direct route towards highly crystalline and monodisperse semiconductor metal oxide nanocrystals. Reports of MnO and Mn3O4 nanocrystals exist where researchers start from Mn(II) salts of formates, acetates, or acetylacetonates. Above 200 C, Mn(II) is shown to be stabilized by the organic ligand used and MnO nanocrystals are formed. However, at lower temperatures, the decomposition of Mn salts appears to thermodynamically favor the formation of spinel-type Mn3O4, which contains both Mn(II) and Mn(III) states. Synthetic conditions are usually inert and only the oxygen from the salt’s anion is expected to contribute to the anion lattice of the product. Atmospheric O2 has been used as an oxidizing agent to assist in the formation of spinel Mn3O4 nanocrystals at 210 C. Furthermore, while organic salts of Mn(III) exists, no reports exist of its use as a precursor in the production of manganese oxide nanocrystals. Herein, we report the formation of colloidal nanocrystals of manganese oxide compounds using Mn(II) acetate and Mn(III) acetylacetonate precursors in high boiling point solvents of oleylamine and octadecylamine. Following, the influence of molecular and atmospheric oxidizing agents on product composition was investigated as well. Furthermore, post-treatment with magnesium precursors has been accomplished to form nanometric spinel-type MgMn2O4 cathode for magnesium batteries. Product purity and structural properties was characterized with powder x-ray diffraction and thermogravimetric analysis. Crystal size and morphology was characterized using electron microscopy imaging methods.

Assessing the influence of oxidizing agents when preparing colloidal spinel-type MgMn2O4 nanocrystals

253rd National Meeting (2017)

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