Electrochemical probing into the active sites of graphitic-layer encapsulated iron oxygen reduction reaction electrocatalysts

Lijie Zhong*, Jens Oluf Jensen, Lars Nilausen Cleemann, Chao Pan, Qingfeng Li

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The graphitic-layer encapsulated iron-containing nanoparticles (G@Fe) have been proposed as a potential type of active and stable non-precious metal electrocatalysts (NPMCs) for the oxygen reduction reaction (ORR). However, the contribution of the encapsulated components to the ORR activity is still unclear compared with the well-recognized surface coordinated FeNx/C structure. Using the strong complexing effect of the iron component with anions, cyanide (CN) in alkaline and thiocyanate (SCN) in acidic media, the metal containing active sites are electrochemically probed. Three representative catalysts are chosen for a comparison including the as-prepared encapsulated G@Fe, commercial Fe/N/C catalyst with iron–nitrogen coordinated surface functionalities and molecular iron phthalocyanine (FePc) containing well-defined structures and compositions. It was found that all samples showed significant shifts of half-wave potentials indicating that surface Fe coordinated sites in all cases. The G@Fe catalyst showed the weakest poisoning effect (the lowest shifts of half-wave potential) compared to the Fe/N/C and FePc catalysts in both electrolytes. These results could be explained that the encapsulated iron components influence the FeNx/C and/or NxC surface functionality.
Original languageEnglish
JournalScience Bulletin
Volume63
Issue number1
Pages (from-to)24-30
ISSN0309-7552
DOIs
Publication statusPublished - 2018

Keywords

  • Encapsulated Fe catalysts
  • Oxygen reduction reaction
  • Ion poisoning
  • Active sites
  • NPMCs

Cite this

@article{6d8dd7e09d764cb7a765c1a85f905709,
title = "Electrochemical probing into the active sites of graphitic-layer encapsulated iron oxygen reduction reaction electrocatalysts",
abstract = "The graphitic-layer encapsulated iron-containing nanoparticles (G@Fe) have been proposed as a potential type of active and stable non-precious metal electrocatalysts (NPMCs) for the oxygen reduction reaction (ORR). However, the contribution of the encapsulated components to the ORR activity is still unclear compared with the well-recognized surface coordinated FeNx/C structure. Using the strong complexing effect of the iron component with anions, cyanide (CN−) in alkaline and thiocyanate (SCN−) in acidic media, the metal containing active sites are electrochemically probed. Three representative catalysts are chosen for a comparison including the as-prepared encapsulated G@Fe, commercial Fe/N/C catalyst with iron–nitrogen coordinated surface functionalities and molecular iron phthalocyanine (FePc) containing well-defined structures and compositions. It was found that all samples showed significant shifts of half-wave potentials indicating that surface Fe coordinated sites in all cases. The G@Fe catalyst showed the weakest poisoning effect (the lowest shifts of half-wave potential) compared to the Fe/N/C and FePc catalysts in both electrolytes. These results could be explained that the encapsulated iron components influence the FeNx/C and/or NxC surface functionality.",
keywords = "Encapsulated Fe catalysts, Oxygen reduction reaction, Ion poisoning, Active sites, NPMCs",
author = "Lijie Zhong and Jensen, {Jens Oluf} and Cleemann, {Lars Nilausen} and Chao Pan and Qingfeng Li",
year = "2018",
doi = "10.1016/j.scib.2017.11.017",
language = "English",
volume = "63",
pages = "24--30",
journal = "Science Bulletin",
issn = "0309-7552",
number = "1",

}

Electrochemical probing into the active sites of graphitic-layer encapsulated iron oxygen reduction reaction electrocatalysts. / Zhong, Lijie; Jensen, Jens Oluf; Cleemann, Lars Nilausen; Pan, Chao; Li, Qingfeng.

In: Science Bulletin, Vol. 63, No. 1, 2018, p. 24-30.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Electrochemical probing into the active sites of graphitic-layer encapsulated iron oxygen reduction reaction electrocatalysts

AU - Zhong, Lijie

AU - Jensen, Jens Oluf

AU - Cleemann, Lars Nilausen

AU - Pan, Chao

AU - Li, Qingfeng

PY - 2018

Y1 - 2018

N2 - The graphitic-layer encapsulated iron-containing nanoparticles (G@Fe) have been proposed as a potential type of active and stable non-precious metal electrocatalysts (NPMCs) for the oxygen reduction reaction (ORR). However, the contribution of the encapsulated components to the ORR activity is still unclear compared with the well-recognized surface coordinated FeNx/C structure. Using the strong complexing effect of the iron component with anions, cyanide (CN−) in alkaline and thiocyanate (SCN−) in acidic media, the metal containing active sites are electrochemically probed. Three representative catalysts are chosen for a comparison including the as-prepared encapsulated G@Fe, commercial Fe/N/C catalyst with iron–nitrogen coordinated surface functionalities and molecular iron phthalocyanine (FePc) containing well-defined structures and compositions. It was found that all samples showed significant shifts of half-wave potentials indicating that surface Fe coordinated sites in all cases. The G@Fe catalyst showed the weakest poisoning effect (the lowest shifts of half-wave potential) compared to the Fe/N/C and FePc catalysts in both electrolytes. These results could be explained that the encapsulated iron components influence the FeNx/C and/or NxC surface functionality.

AB - The graphitic-layer encapsulated iron-containing nanoparticles (G@Fe) have been proposed as a potential type of active and stable non-precious metal electrocatalysts (NPMCs) for the oxygen reduction reaction (ORR). However, the contribution of the encapsulated components to the ORR activity is still unclear compared with the well-recognized surface coordinated FeNx/C structure. Using the strong complexing effect of the iron component with anions, cyanide (CN−) in alkaline and thiocyanate (SCN−) in acidic media, the metal containing active sites are electrochemically probed. Three representative catalysts are chosen for a comparison including the as-prepared encapsulated G@Fe, commercial Fe/N/C catalyst with iron–nitrogen coordinated surface functionalities and molecular iron phthalocyanine (FePc) containing well-defined structures and compositions. It was found that all samples showed significant shifts of half-wave potentials indicating that surface Fe coordinated sites in all cases. The G@Fe catalyst showed the weakest poisoning effect (the lowest shifts of half-wave potential) compared to the Fe/N/C and FePc catalysts in both electrolytes. These results could be explained that the encapsulated iron components influence the FeNx/C and/or NxC surface functionality.

KW - Encapsulated Fe catalysts

KW - Oxygen reduction reaction

KW - Ion poisoning

KW - Active sites

KW - NPMCs

U2 - 10.1016/j.scib.2017.11.017

DO - 10.1016/j.scib.2017.11.017

M3 - Journal article

VL - 63

SP - 24

EP - 30

JO - Science Bulletin

JF - Science Bulletin

SN - 0309-7552

IS - 1

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