Oxygen is the most abundant element in the Earth’s crust. The oxygen reduction reaction (ORR) is also the most important reaction in life processes and energy converting/storage systems. Developing techniques toward high-efficiency ORR remains highly desired and a challenge. Here, we report a N-doped carbon (NC) encapsulated CeO₂/Co interfacial hollow structure (CeO₂–Co–NC) via a generalized strategy for largely increased oxygen species adsorption and improved ORR activities. First, the metallic Co nanoparticles not only provide high conductivity but also serve as electron donors to largely create oxygen vacancies in CeO₂. Second, the outer carbon layer can effectively protect cobalt from oxidation and dissociation in alkaline media and as well imparts its higher ORR activity. In the meanwhile, the electronic interactions between CeO₂ and Co in the CeO₂/Co interface are unveiled theoretically by density functional theory calculations to justify the increased oxygen absorption for ORR activity improvement. The reported CeO₂–Co–NC hollow nanospheres not only exhibit decent ORR performance with a high onset potential (922 mV vs RHE), half-wave potential (797 mV vs RHE), and small Tafel slope (60 mV dec^–1) comparable to those of the state-of-the-art Pt/C catalysts but also possess long-term stability with a negative shift of only 7 mV of the half-wave potential after 2000 cycles and strong tolerance against methanol. This work represents a solid step toward high-efficient oxygen reduction.

中文翻译：

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一种通用的工程设计金属氧化物-金属-碳界面以实现高效氧还原的方法

氧气是地壳中最丰富的元素。氧还原反应（ORR）也是生命过程和能量转换/存储系统中最重要的反应。朝着高效ORR的方向发展技术仍然是人们的迫切需求和挑战。在这里，我们通过大量增加氧物种吸附和改善ORR活性的通用策略，报告了一种N掺杂的碳（NC）封装的CeO ₂ / Co界面空心结构（CeO ₂ -Co-NC）。首先，金属Co纳米颗粒不仅提供高电导率，而且还充当电子给体，从而在CeO _2中大量产生氧空位。第二，外碳层可以有效地保护钴免受碱性介质中的氧化和离解，并赋予其更高的ORR活性。同时，通过密度泛函理论计算从理论上揭示了CeO ₂ / Co界面中CeO ₂和Co之间的电子相互作用，以证明增加的氧吸收可改善ORR活性。报道的CeO ₂ -Co-NC中空纳米球不仅表现出良好的ORR性能，而且具有高的起始电势（922 mV vs RHE），半波电势（797 mV vs RHE）和小的Tafel斜率（60 mV dec ^–1））可以与最先进的Pt / C催化剂相媲美，但还具有长期稳定性，在2000次循环后负位移仅为半波电势的7 mV，并且对甲醇具有很强的耐受性。这项工作代表了朝着高效氧气还原迈出的坚实一步。