Spinel-type oxides are technologically important in many fields, including electronics, magnetism, catalysis and electrochemical energy storage and conversion. Typically, these materials are prepared by conventional ceramic routes that are energy consuming and offer limited control over shape and size. Moreover, for mixed-metal oxide spinels (for example, Co(x)Mn(3-x)O4), the crystallographic phase sensitively correlates with the metal ratio, posing great challenges to synthesize active product with simultaneously tuned phase and composition. Here we report a general synthesis of ultrasmall cobalt manganese spinels with tailored structural symmetry and composition through facile solution-based oxidation-precipitation and insertion-crystallization process at modest condition. As an example application, the nanocrystalline spinels catalyse the oxygen reduction/evolution reactions, showing phase and composition co-dependent performance. Furthermore, the mild synthetic strategy allows the formation of homogeneous and strongly coupled spinel/carbon nanocomposites, which exhibit comparable activity but superior durability to Pt/C and serve as efficient catalysts to build rechargeable Zn-air and Li-air batteries.

中文翻译：

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钴锰尖晶石纳米粒子的相和组成可控的合成，以有效地进行氧电催化。

尖晶石型氧化物在许多领域在技术上都很重要，包括电子，磁性，催化以及电化学能的存储和转化。通常，这些材料是通过常规的陶瓷路线制备的，该路线消耗能量并且对形状和尺寸的控制有限。此外，对于混合金属氧化物尖晶石（例如，Co（x）Mn（3-x）O4），晶体相与金属比敏感地相关，这对合成具有同时调整的相和组成的活性产物提出了很大的挑战。在这里，我们通过适度的基于溶液的氧化沉淀和插入结晶过程，报告了具有定制的结构对称性和组成的超小型钴锰尖晶石的一般合成方法。作为示例应用程序，纳米晶尖晶石催化氧还原/放出反应，表现出相和组成的相互依赖的性能。此外，温和的合成策略允许形成均质且牢固偶联的尖晶石/碳纳米复合材料，该复合材料显示出可比的活性，但与Pt / C相比具有出色的耐久性，并且可以用作构建可充电Zn-空气和Li-空气电池的有效催化剂。