Effect of Zn atom in Fe-N-C catalysts for electro-catalytic reactions: theoretical considerations
Autor: | Zhi-Bin Chen, Jianglan Shui, Riming Hu, Jia-Xiang Shang, Xin Wan, Fu-He Wang, Yongcheng Li |
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Rok vydání: | 2020 |
Předmět: |
biology
Chemistry Graphene Inorganic chemistry Oxygen evolution Active site chemistry.chemical_element 02 engineering and technology Activation energy 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Nitrogen Atomic and Molecular Physics and Optics 0104 chemical sciences law.invention Catalysis law Specific surface area biology.protein General Materials Science Density functional theory Electrical and Electronic Engineering 0210 nano-technology |
Zdroj: | Nano Research. 14:611-619 |
ISSN: | 1998-0000 1998-0124 |
Popis: | Due to the high specific surface area, abundant nitrogen and micropores, ZIF-8 is a commonly used precursor for preparing high performance Fe-N-C catalysts. However, the Zn element is inevitably remained in the prepared Fe-N-C catalyst. Whether the residual Zn element affects the catalytic activity and active site center of the Fe-N-C catalyst caused widespread curiosity, but has not been studied yet. Herein, we built several Fe, Zn, and N co-doped graphene models to investigate the effect of Zn atoms on the electrocatalytic performance of Fe-N-C catalysts by using density functional theory method. The calculation results show that all the calculated Fe-Zn-Nx structures are thermodynamically stable due to the negative formation energies and relative stabilities. The active sites around Fe and Zn atoms in the structure of Fe-Zn-N6(III) show the lowest oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) overpotentials of 0.38 and 0.43 V, respectively. The bridge site of Fe-Zn in Fe-Zn-N5 shows the lowest ηHER of −0.26 V. A few structures with a better activity than that of FeN4 or ZnN4 are attributed to the synergistic effects between Fe and Zn atoms. The calculated ORR reaction pathways on Fe-Zn-N6(III) show that H2O is the final product and the ORR mechanism on the catalyst would be a four-electron process, and the existence of Zn element in the Fe-N-C catalysts plays a key role in reducing the ORR activation energy barrier. The results are helpful for the deep understand of high-performance Fe-N-C catalysts. |
Databáze: | OpenAIRE |
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