The rational modulation of composition and structure is critical for the development of robust and efficient oxygen evolution reaction (OER) catalysts for water splitting. In this study, an onion-like N-doped carbon nanorods hybrid (denoted as ONC) with encapsulated Ni/Fe₃O₄ heterostructures has been fabricated by the pyrolysis of an NiFe-based coordination polymer under a N₂ atmosphere. The nanorod-like morphology is transferred from the polymer to the hybrids and generates ONC nanolayers encapsulated with core–shell Ni/Fe₃O₄ nanostructures. The synergistic effects between the ONC layers and the encapsulated Ni/Fe₃O₄ heterostructures result in high electronic conductivity due to the nitrogen-doped carbon with an appropriate level of defects and enlarged electrochemical surface area due to the well-defined mesoporous morphology. Compared with Ni@ONC, Fe₃O₄@ONC, NiFe₂O₄ and commercial RuO₂ electrocatalysts, the as-prepared Ni/Fe₃O₄@ONC exhibits extraordinary electrocatalytic activity for water oxidation with an overpotential of merely 296 mV at 10 mA cm⁻² and a small Tafel slope of 61 mV dec⁻¹. This Ni/Fe₃O₄@ONC OER catalyst highlights the great potential of integrating hetero-composite nanocatalysts with hetero-atom doped nanocarbon supports for the development of high-performance electrocatalysts for renewable energy applications.

中文翻译：

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将Ni / Fe ₃ O ₄异质结构封装在洋葱状的N掺杂碳纳米棒中可实现水氧化的协同电催化作用†

组成和结构的合理调节对于开发用于水分解的稳健而高效的析氧反应（OER）催化剂至关重要。在这项研究中，通过在N ₂气氛下热解NiFe基配位聚合物，制备了具有封装的Ni / Fe ₃ O ₄异质结构的洋葱状N掺杂碳纳米棒杂化物（表示为ONC）。纳米棒状形态从聚合物转移到杂化物中，并生成用核-壳Ni / Fe ₃ O ₄纳米结构封装的ONC纳米层。ONC层与封装的Ni / Fe ₃ O ₄之间的协同效应异质结构由于掺杂了氮的碳具有适当水平的缺陷而导致了高电子电导率，并且由于定义明确的中孔形态而扩大了电化学表面积。与Ni @ ONC，Fe ₃ O ₄ @ ONC，NiFe ₂ O ₄和市售RuO ₂电催化剂相比，所制备的Ni / Fe ₃ O ₄ @ONC对水氧化表现出非凡的电催化活性，其超电位在296 mV时仅为296 mV。 10 mA cm ^-2，小的Tafel斜率为61 mV dec ^-1。镍/铁₃ O ₄@ONC OER催化剂突出了将杂化复合纳米催化剂与杂原子掺杂的纳米碳载体整合在一起的巨大潜力，以开发可再生能源应用中的高性能电催化剂。