催化作用
密度泛函理论
化学
无机化学
过渡金属
计算化学
有机化学
作者
Yongcheng Li,Riming Hu,Zhibin Chen,Xin Wan,Jiaxiang Shang,Fu-He Wang,Jianglan Shui
出处
期刊:Nano Research
[Springer Nature]
日期:2020-11-06
卷期号:14 (3): 611-619
被引量:61
标识
DOI:10.1007/s12274-020-3072-6
摘要
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.
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