Evolution Pathway from Iron Compounds to Fe1(II)-N4 Sites through Gas-Phase Iron during Pyrolysis

Jingkun Li; Li Jiao; Evan Wegener; Lynne Larochelle Richard; Ershuai Liu; Andrea Zitolo; Moulay Tahar Sougrati; Sanjeev Mukerjee; Zipeng Zhao; Yu Huang; Fan Yang; Sichen Zhong; Hui Xu; A. Jeremy Kropf; Frédéric Jaouen; Deborah J. Myers; Qingying Jia

doi:10.1021/jacs.9b11197

Evolution Pathway from Iron Compounds to Fe₁(II)-N₄ Sites through Gas-Phase Iron during Pyrolysis

Jingkun Li
, Li Jiao
, Evan Wegener
, Lynne Larochelle Richard
, Ershuai Liu
, Andrea Zitolo
, Moulay Tahar Sougrati
, Sanjeev Mukerjee
, Zipeng Zhao
, Yu Huang
, Fan Yang
, Sichen Zhong
, Hui Xu
, A. Jeremy Kropf
, Frédéric Jaouen
, Deborah J. Myers^*
, Qingying Jia

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

241 Citations (Scopus)

Abstract

Pyrolysis is indispensable for synthesizing highly active Fe-N-C catalysts for the oxygen reduction reaction (ORR) in acid, but how Fe, N, and C precursors transform to ORR-active sites during pyrolysis remains unclear. This knowledge gap obscures the connections between the input precursors and the output products, clouding the pathway toward Fe-N-C catalyst improvement. Herein, we unravel the evolution pathway of precursors to ORR-active catalyst comprised exclusively of single-atom Fe₁(II)-N₄ sites via in-temperature X-ray absorption spectroscopy. The Fe precursor transforms to Fe oxides below 300 °C and then to tetrahedral Fe₁(II)-O₄ via a crystal-to-melt-like transformation below 600 °C. The Fe₁(II)-O₄ releases a single Fe atom that diffuses into the N-doped carbon defect forming Fe₁(II)-N₄ above 600 °C. This vapor-phase single Fe atom transport mechanism is verified by synthesizing Fe₁(II)-N₄ sites via "noncontact pyrolysis" wherein the Fe precursor is not in physical contact with the N and C precursors during pyrolysis.

Original language	English
Pages (from-to)	1417-1423
Number of pages	7
Journal	Journal of the American Chemical Society
Volume	142
Issue number	3
DOIs	https://doi.org/10.1021/jacs.9b11197
Publication status	Published - 22 Jan 2020
Externally published	Yes

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Li, J., Jiao, L., Wegener, E., Richard, L. L., Liu, E., Zitolo, A., Sougrati, M. T., Mukerjee, S., Zhao, Z., Huang, Y., Yang, F., Zhong, S., Xu, H., Kropf, A. J., Jaouen, F., Myers, D. J., & Jia, Q. (2020). Evolution Pathway from Iron Compounds to Fe₁(II)-N₄ Sites through Gas-Phase Iron during Pyrolysis. Journal of the American Chemical Society, 142(3), 1417-1423. https://doi.org/10.1021/jacs.9b11197

@article{9f4fa2995df54fadbf0278337d7ffa21,

title = "Evolution Pathway from Iron Compounds to Fe1(II)-N4 Sites through Gas-Phase Iron during Pyrolysis",

abstract = "Pyrolysis is indispensable for synthesizing highly active Fe-N-C catalysts for the oxygen reduction reaction (ORR) in acid, but how Fe, N, and C precursors transform to ORR-active sites during pyrolysis remains unclear. This knowledge gap obscures the connections between the input precursors and the output products, clouding the pathway toward Fe-N-C catalyst improvement. Herein, we unravel the evolution pathway of precursors to ORR-active catalyst comprised exclusively of single-atom Fe1(II)-N4 sites via in-temperature X-ray absorption spectroscopy. The Fe precursor transforms to Fe oxides below 300 °C and then to tetrahedral Fe1(II)-O4 via a crystal-to-melt-like transformation below 600 °C. The Fe1(II)-O4 releases a single Fe atom that diffuses into the N-doped carbon defect forming Fe1(II)-N4 above 600 °C. This vapor-phase single Fe atom transport mechanism is verified by synthesizing Fe1(II)-N4 sites via {"}noncontact pyrolysis{"} wherein the Fe precursor is not in physical contact with the N and C precursors during pyrolysis.",

author = "Jingkun Li and Li Jiao and Evan Wegener and Richard, \{Lynne Larochelle\} and Ershuai Liu and Andrea Zitolo and Sougrati, \{Moulay Tahar\} and Sanjeev Mukerjee and Zipeng Zhao and Yu Huang and Fan Yang and Sichen Zhong and Hui Xu and Kropf, \{A. Jeremy\} and Fr{\'e}d{\'e}ric Jaouen and Myers, \{Deborah J.\} and Qingying Jia",

note = "Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

year = "2020",

month = jan,

day = "22",

doi = "10.1021/jacs.9b11197",

language = "English",

volume = "142",

pages = "1417--1423",

journal = "Journal of the American Chemical Society",

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Li, J, Jiao, L, Wegener, E, Richard, LL, Liu, E, Zitolo, A, Sougrati, MT, Mukerjee, S, Zhao, Z, Huang, Y, Yang, F, Zhong, S, Xu, H, Kropf, AJ, Jaouen, F, Myers, DJ & Jia, Q 2020, 'Evolution Pathway from Iron Compounds to Fe₁(II)-N₄ Sites through Gas-Phase Iron during Pyrolysis', Journal of the American Chemical Society, vol. 142, no. 3, pp. 1417-1423. https://doi.org/10.1021/jacs.9b11197

TY - JOUR

T1 - Evolution Pathway from Iron Compounds to Fe1(II)-N4 Sites through Gas-Phase Iron during Pyrolysis

AU - Li, Jingkun

AU - Jiao, Li

AU - Wegener, Evan

AU - Richard, Lynne Larochelle

AU - Liu, Ershuai

AU - Zitolo, Andrea

AU - Sougrati, Moulay Tahar

AU - Mukerjee, Sanjeev

AU - Zhao, Zipeng

AU - Huang, Yu

AU - Yang, Fan

AU - Zhong, Sichen

AU - Xu, Hui

AU - Kropf, A. Jeremy

AU - Jaouen, Frédéric

AU - Myers, Deborah J.

AU - Jia, Qingying

PY - 2020/1/22

Y1 - 2020/1/22

N2 - Pyrolysis is indispensable for synthesizing highly active Fe-N-C catalysts for the oxygen reduction reaction (ORR) in acid, but how Fe, N, and C precursors transform to ORR-active sites during pyrolysis remains unclear. This knowledge gap obscures the connections between the input precursors and the output products, clouding the pathway toward Fe-N-C catalyst improvement. Herein, we unravel the evolution pathway of precursors to ORR-active catalyst comprised exclusively of single-atom Fe1(II)-N4 sites via in-temperature X-ray absorption spectroscopy. The Fe precursor transforms to Fe oxides below 300 °C and then to tetrahedral Fe1(II)-O4 via a crystal-to-melt-like transformation below 600 °C. The Fe1(II)-O4 releases a single Fe atom that diffuses into the N-doped carbon defect forming Fe1(II)-N4 above 600 °C. This vapor-phase single Fe atom transport mechanism is verified by synthesizing Fe1(II)-N4 sites via "noncontact pyrolysis" wherein the Fe precursor is not in physical contact with the N and C precursors during pyrolysis.

AB - Pyrolysis is indispensable for synthesizing highly active Fe-N-C catalysts for the oxygen reduction reaction (ORR) in acid, but how Fe, N, and C precursors transform to ORR-active sites during pyrolysis remains unclear. This knowledge gap obscures the connections between the input precursors and the output products, clouding the pathway toward Fe-N-C catalyst improvement. Herein, we unravel the evolution pathway of precursors to ORR-active catalyst comprised exclusively of single-atom Fe1(II)-N4 sites via in-temperature X-ray absorption spectroscopy. The Fe precursor transforms to Fe oxides below 300 °C and then to tetrahedral Fe1(II)-O4 via a crystal-to-melt-like transformation below 600 °C. The Fe1(II)-O4 releases a single Fe atom that diffuses into the N-doped carbon defect forming Fe1(II)-N4 above 600 °C. This vapor-phase single Fe atom transport mechanism is verified by synthesizing Fe1(II)-N4 sites via "noncontact pyrolysis" wherein the Fe precursor is not in physical contact with the N and C precursors during pyrolysis.

UR - https://www.scopus.com/pages/publications/85078335253

U2 - 10.1021/jacs.9b11197

DO - 10.1021/jacs.9b11197

M3 - Article

C2 - 31880925

AN - SCOPUS:85078335253

SN - 0002-7863

VL - 142

SP - 1417

EP - 1423

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 3

ER -

Evolution Pathway from Iron Compounds to Fe₁(II)-N₄ Sites through Gas-Phase Iron during Pyrolysis

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