La, Mn and Co-based materials with diverse compositions encapsulated in N-doped carbon materials were synthesized by an in-situ sol-gel method. The as-prepared materials were physically activated with CO giving as a result composites with excellent performance for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The composites were characterized by different physicochemical techniques revealing the importance of porosity created by CO activation. This crucial step increases the number of accessible active sites such as Co-N-C sites, Co/MnO heterointerfaces and graphitic N groups. Moreover, the formation of LaOCO was detected to enhance electrical conductivity and electrochemical performance and it is active for ORR. Although the composite containing La, Mn and Co has less concentration of the highly active sites, its small particle size favour a better distribution of these sites. The Co-containing composites were tested as air-electrodes in a Zn-air battery and compared to commercial electrocatalysts. All composites showed a better operation in terms of higher cyclability and higher energy density which is a consequence of metal nanostructures encapsulation in N-doped porous carbon shells. Interestingly, the pure Co-based composite showed an outstanding performance related to the high concentration of the Co-N-C active sites that provide high activity and stability.

中文翻译：

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用于锌空气电池应用的封装氮掺杂碳金属氧化物纳米结构的原位合成

采用原位溶胶-凝胶法合成了封装在氮掺杂碳材料中的不同成分的La、Mn和Co基材料。所制备的材料用 CO 进行物理活化，得到的复合材料在氧还原反应 (ORR) 和析氧反应 (OER) 方面均具有优异的性能。通过不同的物理化学技术对复合材料进行了表征，揭示了 CO 活化产生的孔隙率的重要性。这一关键步骤增加了可访问活性位点的数量，例如 Co-NC 位点、Co/MnO 异质界面和石墨 N 基团。此外，检测到LaOCO的形成可以增强电导率和电化学性能，并且对ORR具有活性。虽然含有La、Mn和Co的复合材料的高活性位点浓度较低，但其较小的粒径有利于这些位点更好的分布。含钴复合材料作为空气电极在锌空气电池中进行了测试，并与商用电催化剂进行了比较。所有复合材料在更高的循环性能和更高的能量密度方面表现出更好的性能，这是金属纳米结构封装在氮掺杂多孔碳壳中的结果。有趣的是，纯钴基复合材料表现出与高浓度的 Co-NC 活性位点相关的出色性能，可提供高活性和稳定性。