Electrocatalysts for oxygen reactions play a vital role in the applications of energy conversion devices, such as in fuel cells, water splitting, and metal–air batteries. Developing novel nonprecious bifunctional electrocatalysts is particularly essential for improved-performance metal–air batteries by overcoming sluggish oxygen reactions. Herein, we demonstrate a composite electrocatalyst with bimetallic CoNi alloy nanocrystals embedded within nitrogen-doped highly graphitic carbon spheres (N-CoNi/PCS). Owing to the efficient design strategy, such a composite electrocatalyst exhibits a unique pomegranate-like morphology and microstructure. When applied to an alkaline electrolyte system, the porous electrocatalyst delivers a low half-wave potential of 0.80 V toward ORR and overpotential of 540 mV toward OER with excellent durability. The high performance is systematically studied and ascribed to the unique nanoarchitecture which enables fast ion transportation and electron transfer, easy access to abundant active sites, and robustness. This work forwards the field of fabricating a highly active, affordable, and stable bifunctional electrocatalyst for energy conversion.

中文翻译：

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双金属CoNi合金纳米粒子嵌入类似石榴的氮掺杂碳球中，用于电催化氧的还原和释放

用于氧反应的电催化剂在能量转换装置的应用中起着至关重要的作用，例如在燃料电池，水分解和金属空气电池中。通过克服缓慢的氧气反应，开发新型的非贵金属双功能电催化剂对于提高性能的金属空气电池尤为重要。在本文中，我们展示了一种复合电催化剂，其中双金属CoNi合金纳米晶体嵌入氮掺杂的高度石墨碳球（N-CoNi / PCS）中。由于有效的设计策略，这种复合电催化剂表现出独特的石榴状形态和微观结构。当应用于碱性电解质系统时，该多孔电催化剂以极好的耐久性向ORR传递0.80 V的低半波电势，向OER传递540 mV的超电势。系统地研究了高性能，并将其归因于独特的纳米结构，该结构可实现快速的离子传输和电子转移，易于访问的大量活性位点以及坚固性。这项工作推进了制造用于能量转换的高活性，价格合理和稳定的双功能电催化剂的领域。