Kim, Minhyoung Yoo, Ji Mun Ahn, Chi-Yeong Jang, Jue-Hyuk Son, Yoon Jun Shin, Heejong Kang, Jiho Kang, Yun Sik Yoo, Sung Jong Lee, Kug-Seung Sung, Yung-Eun 2024-01-19T18:32:21Z 2024-01-19T18:32:21Z 2021-09-04 2019-12-18 1867-3880 https://pubs.kist.re.kr/handle/201004/119187 Fe-N-C catalysts synthesized by pyrolysis of Fe and N precursors have been intensively studied due to their remarkable activities for the electrochemical oxygen reduction reaction (ORR). Although Fe-N-4 coordinated structures have been suggested as active sites by recent spectroscopic studies, the influence of precursor coordination on the generation of the active sites during high-temperature pyrolysis is not well understood. In this work, phenanthroline isomers were used as systematic model precursors to reveal the correlation between precursor coordination and active site formation in Fe-N-C catalysts. Coordination between Fe and each phenanthroline isomer was effectively controlled by the molecular structure: monodentate (1,7- and 4,7-phenanthroline) and bidentate coordination (1,10-phenanthroline). Through X-ray absorption spectroscopy and X-ray photoelectron spectroscopy study, large difference in atomic distribution of both Fe and N was revealed; the preferential formation of Fe-N-x active sites was featured only in Fe(1,10-phenanthroline)/KB with homogeneously distributed Fe and highly retained pyridinic N. With Fe-N-x active site moieties, Fe(1,10-phenanthroline)/KB exhibited superior ORR activity and stability in alkaline half-cell and full-cell tests. These results highlight the importance of the use of precursors with multiple coordination (i. e. bidentate) for the effective derivation of Fe-N-x active sites for highly active and stable ORR electrocatalysts. English WILEY-V C H VERLAG GMBH METAL-ORGANIC-FRAMEWORK PEM FUEL-CELLS CATALYTIC SITES IRON CARBON POLYANILINE PERFORMANCE PYROLYSIS COMPLEXES GRAPHENE Rational Generation of Fe-N-x Active Sites in Fe-N-C Electrocatalysts Facilitated by Fe-N Coordinated Precursors for the Oxygen Reduction Reaction Article 10.1002/cctc.201901242 1 CHEMCATCHEM, v.11, no.24, pp.5982 - 5988 CHEMCATCHEM 11 24 5982 5988 scie scopus 000490011500001 2-s2.0-85074424080 Chemistry, Physical Chemistry Article METAL-ORGANIC-FRAMEWORK PEM FUEL-CELLS CATALYTIC SITES IRON CARBON POLYANILINE PERFORMANCE PYROLYSIS COMPLEXES GRAPHENE Fe-N-C electrocatalyst Oxygen reduction reaction Active site formation Coordination state Precursor