State Key Laboratory of Precision Spectroscopy, Shanghai Key Laboratory of Magnetic Resonance, Institute of Functional Materials, School of Physics and Materials Science , East China Normal University , Shanghai 200062 , P. R. China.
ACS Appl Mater Interfaces. 2018 May 2;10(17):14684-14697. doi: 10.1021/acsami.8b00953. Epub 2018 Apr 18.
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 (MnO ) 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 MnO or δ-MnO 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, N adsorption-desorption analysis and other techniques, their crystal structure, detailed morphology, and microstructure features were unambiguously revealed. Specifically, their electrochemical Li-ion insertion/extraction properties were well evaluated, and it turns out that these unique 3D microcuboids could achieve a sustained superior lithium-storage performance especially at high rates benefited from the well-orchestrated structural characteristics (MnO microcuboids: 890.7, 767.4, 560.1, and 437.1 mAh g after 400 cycles at 0.2, 0.5, 1, and 2 A g, respectively; δ-MnO microcuboids: 991.5, 660.8, 504.4, and 362.1 mAh g after 400 cycles at 0.2, 0.5, 1, and 2 A g, respectively). To our knowledge, this is the most durable high-rate capability as well as the highest reversible capacity ever reported for pure MnO anodes, which even surpass most of their hybrids. This facile, green, and economical strategy renews the traditional MOF-derived synthesis for highly tailorable functional materials and opens up new opportunities for metal-oxide electrodes with high performance.
理性设计和精细控制金属氧化物材料的结构依赖性应用的纹理特性仍然是巨大的挑战。在这里，我们提出了一种环保且简便的方法，通过在室温下使用一步溶液相反应方案，从基于 Mn-MOF-74 的模板智能地制造三维（3D）层层锰氧化物（MnO）分级介孔微立方体。通过金属有机骨架（MOF）配体与碱性水溶液中的 OH 的受控交换以及中间锰氢氧化物的原位氧化，Mn-MOF-74 模板/前体很容易转化为 MnO 或δ-MnO 对应物，分别由初级纳米颗粒和纳米片构建块组成，形态保留良好。通过 X 射线衍射、透射电子显微镜（TEM）、扫描电子显微镜、高分辨率 TEM、N 吸附-解吸分析和其他技术，明确揭示了它们的晶体结构、详细形态和微观结构特征。具体来说，对它们的电化学锂离子插入/提取性能进行了很好的评估，结果表明，这些独特的 3D 微立方体由于协调良好的结构特征（MnO 微立方体：在 0.2、0.5、1 和 2 A g 下 400 次循环后分别为 890.7、767.4、560.1 和 437.1 mAh g；δ-MnO 微立方体：在 0.2、0.5、1 和 2 A g 下 400 次循环后分别为 991.5、660.8、504.4 和 362.1 mAh g），能够实现持续的优异的锂存储性能，尤其是在高倍率下。为了我们的知识，这是纯 MnO 阳极迄今为止报道的最持久的高倍率能力以及最高的可逆容量，甚至超过了它们中的大多数混合物。这种简便、绿色且经济的策略为高度可定制的功能材料更新了传统的 MOF 衍生合成，并为高性能的金属氧化物电极开辟了新的机会。
