Xue Yuanyuan, Chen Letian, Zhang Lijuan, Zheng Gengfeng, Zhang Xu, Zhou Zhen
Laboratory of Advanced Materials, Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University Shanghai 200438 China
School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Renewable Energy Conversion and Storage Center (ReCast), Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University Tianjin 300350 China
Chem Sci. 2025 Jan 13;16(7):3323-3328. doi: 10.1039/d4sc08019j. eCollection 2025 Feb 12.
The exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performances of core-shell catalysts are well documented, yet their activity and durability origins have been interpreted only based on the static structures. Herein we employ a NiFe alloy coated with a nitrogen-doped graphene-based carbon shell (NiFe@NC) as a model system to elucidate the active structure and stability mechanism for the ORR and OER by combining constant potential computations, molecular dynamic simulations, and experiments. The results reveal that the synergistic effects between the alloy core and carbon shell facilitate the formation of Fe-N-C active sites and replenish metal sites when central metal atoms detach. The metal core and catalytic environment function as an "ammunition depot" and "automatic loader," respectively, ensuring long-term stability. Notably, atomic diffusion behaviors are identified as critical for the formation and regeneration of active sites during the ORR/OER. This work provides new insights into the activity and stability of core-shell catalysts and emphasizes the importance of reconstruction and dynamic structural evolution in electrocatalysts.
核壳催化剂卓越的氧还原反应（ORR）和析氧反应（OER）性能已有充分记录，但其活性和耐久性的根源仅基于静态结构进行了解释。在此，我们采用涂覆有氮掺杂石墨烯基碳壳的镍铁合金（NiFe@NC）作为模型体系，通过结合恒电位计算、分子动力学模拟和实验，阐明ORR和OER的活性结构及稳定性机制。结果表明，合金核与碳壳之间的协同效应促进了Fe-N-C活性位点的形成，并在中心金属原子脱离时补充金属位点。金属核和催化环境分别起到“弹药库”和“自动装填器”的作用，确保了长期稳定性。值得注意的是，原子扩散行为被确定为ORR/OER过程中活性位点形成和再生的关键因素。这项工作为核壳催化剂的活性和稳定性提供了新的见解，并强调了电催化剂中重构和动态结构演变的重要性。
