1. Facile synthesis of Fe3C-dominated Fe/Fe3C/FeN0.0324 multiphase nanocrystals embedded in nitrogen-modified graphitized carbon as efficient pH-universal catalyst for oxygen reduction reaction and zinc-air battery.
- Author
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Li, Guang, Sheng, Kuang, Lei, Yu, Yang, Juan, Chen, Yulian, Guo, Xiaowei, Chen, Gairong, Chang, Baobao, Wu, Tianjing, and Wang, Xianyou
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GRAPHITIZATION , *ALKALINE batteries , *OXYGEN reduction , *ZINC catalysts , *NANOCRYSTALS , *OPEN-circuit voltage , *DENSITY functional theory , *ACTIVATION energy - Abstract
[Display omitted] • A facile strategy is developed to synthesize multiphase Fe-based catalyst. • The Fe/Fe 3 C/FeN 0.0324 @N-GC exhibits excellent pH-universal ORR activity. • It possesses better battery performance than Pt/C in alkaline and neutral media. • The activity is attributed to the synergy among Fe-based sites dominated by Fe 3 C. • The active of Fe-based sites is probed by DFT calculation: Fe 3 C > Fe > FeN 0.0324. Iron-based nitrogen-doped carbonaceous materials are currently the most promising alternative towards oxygen reduction reaction (ORR) electrocatalysts due to the highly efficient active sites of single-atom Fe-N X coordination. However, the fact that iron-containing nanocrystals are easier to form during pyrolysis without additional tuning while providing activity comparable to single-atom sites cannot be ignored. Herein, we propose a facile and efficient strategy to synthesize iron nanocrystals sites with multiphase embedded in porous nitrogen-doped graphitized carbon (Fe/Fe 3 C/FeN 0.0324 @N-GC-X, X = 700, 850, and 1000). Based on highly active Fe 3 C@N-GC sites and the synergistic effect of Fe 3 C-dominated multiple iron-based, Fe/Fe 3 C/FeN 0.0324 @N-GC-850 exhibits excellent electrocatalytic activity towards ORR in pH-universal media. Specifically, it exhibits satisfactory onset potential (E onset), half-wave potential (E 1/2) and stability, and thus surpassing the benchmark Pt/C in both alkaline and neutral media as well as approaching Pt/C in acidic media. When employed as an air cathode in zinc-air batteries (ZABs), it also presents higher open-circuit voltage (OCV), discharge voltage plateaus, capacity, and peak power density compared with Pt/C. Density functional theory (DFT) calculations demonstrate that Fe 3 C (2 2 0)/N-GC has lower activation energy during ORR process and the overpotential generated by Fe 3 C/N-GC (0.7 V) is obviously less than one of Fe/N-GC (1.37 V) and FeN 0.0324 /N-GC (1.69 V). [ABSTRACT FROM AUTHOR]
- Published
- 2023
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