Herein, palladium (Pd)-anchored hierarchical structure metallic Co coated by nitrogen-doped carbon (Pd-NC/Co HS) is constructed as a bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). For Pd-NC/Co HS, the carbon shell isolates the metallic Co core from the electrolyte for avoiding corrosion, while the hierarchical metallic Co enhances the overall structural stability, mass transmission, and intrinsic electron transfer for beneficial electrocatalysis. Notably, the metallic Co core underneath carbon suitably tunes the microstructure of interface Pd nanocrystals, forming electron-deficient Pd which is highly active for OER. Moreover, this carbon-isolation induced indirect metal–metal interaction (IMMI) between metallic Co core and Pd boosts the ORR of the hybrid Pd-NC/Co HS. Theoretical calculations further show that, compared to Pd/C, Pd-NC/Co HS possesses an obvious decreased energy barrier for ORR potential limiting step of *OH desorption and for OER potential limiting step of the conversion from *OH to *O, further confirming the appropriate regulation of Co on Pd via carbon shell. The zinc-air battery (168.25 mW/cm) and magnesium-air battery (89.98 mW/cm) driven by Pd-NC/Co HS deliver a higher peak power density than the one driven by precious metal catalysts, along with a longer operation time, showing promising application potentials.

中文翻译：

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碳隔离诱导的间接金属-金属相互作用调节分级钴核对锚定钯的双功能氧电催化作用

在此，氮掺杂碳涂层的钯（Pd）锚定分级结构金属Co（Pd-NC/Co HS）被构建为氧还原反应（ORR）和析氧反应（OER）的双功能催化剂。对于 Pd-NC/Co HS，碳壳将金属 Co 核与电解质隔离，以避免腐蚀，而分级金属 Co 增强了整体结构稳定性、质量传输和固有电子转移，有利于电催化。值得注意的是，碳下方的金属Co核适当地调节了界面Pd纳米晶体的微观结构，形成对OER具有高度活性的缺电子Pd。此外，这种碳隔离诱导金属Co核和Pd之间的间接金属-金属相互作用（IMMI）提高了杂化Pd-NC/Co HS的ORR。理论计算进一步表明，与Pd/C相比，Pd-NC/Co HS对于*OH脱附的ORR电位限制步骤和*OH到*O转化的OER电位限制步骤具有明显降低的能垒，进一步确认通过碳壳对 Co 对 Pd 的适当调节。 Pd-NC/Co HS驱动的锌空气电池（168.25 mW/cm）和镁空气电池（89.98 mW/cm）比贵金属催化剂驱动的电池具有更高的峰值功率密度，并且运行时间更长时间，显示出良好的应用潜力。