Green and Rational Design of 3D Layer-by-Layer MnOx Hierarchically Mesoporous Microcuboids from MOF Templates for High-Rate and Long-Life Li-Ion Batteries

Rational design and delicate control on the textural properties of metal-oxide materials for diverse structure-dependent applications still remain formidable challenges. Here, we present an eco-friendly and facile approach to smartly fabricate three-dimensional (3D) layer-by-layer manganese oxide (MnOx) hierarchical mesoporous microcuboids from a Mn-MOF-74-based template, using a one-step solution-phase reaction scheme at room temperature. Through the controlled exchange of metal–organic framework (MOF) ligand with OH– in alkaline aqueous solution and in situ oxidation of manganese hydroxide intermediate, the Mn-MOF-74 template/precursor was readily converted to Mn3O4 or δ-MnO2 counterpart consisting of primary nanoparticle and nanosheet building blocks, respectively, with well-retained morphology. By X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy, high-resolution TEM, N2 adsorption–desorption analysis and other techniques, their crystal structure, detailed morphol...