Synthesis of octahedral Mn3O4 crystals and their derived Mn3O4–MnO2 heterostructures via oriented growth

In this work, we demonstrate a facile hydrothermal method to synthesize well-defined Mn3O4 octahedral crystals and their transformation to a unique heterostructure with Mn3O4 as the core and MnO2 nanosheets as the shell.