Spinel ZnMn2O4 nanoplate assemblies fabricated via “escape-by-crafty-scheme” strategy

Abstract

A two-step process that differs in important details from previous methods used to prepare ZnMn₂O₄ nanoplate assemblies has been reported. This material was prepared by thermal transformation of metal–organic nanoparticles into metal–oxide nanoparticles based on the “escape-by-crafty-scheme” strategy. Firstly, the nanoscale mixed-metal–organic frameworks (MMOFs) precursor, ZnMn₂–ptcda (ptcda = perylene-3,4,9,10-tetracarboxylic dianhydride), containing Zn²⁺ and Mn²⁺, was prepared by the designed soft chemical assembly of mixed metal ions and organic ligands at a molecular scale. In a second step, the MMOFs are thermally transformed into spinel structured ZnMn₂O₄ with morphology inherited from the MMOFs precursors. The well-crystallized spinel structure can be formed by thermal treatment of ZnMn₂–ptcda at 350 °C, and is formed at temperatures ≥450 °C using the co-precipitation method. This “escape-by-crafty-scheme” strategy can be extended to the preparation of other spinel metal–oxide nanoparticles, e.g. CoMn₂O₄, and NiMn₂O₄, with well-defined morphology inherited from the metal–organic precursors. The ZnMn₂O₄ nanoplate assemblies thermally treated at 450 °C have potential application in lithium ion batteries as anode materials, which show high specific capacity and good cyclability.