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  • 02월 19일 23시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제119회 대한화학회 학술발표회, 총회 및 기기전시회 안내 A General Approach to Preferential Formation of Active Fe–Nx Sites in Fe–N/C Electrocatalysts for Efficient Oxygen Reduction Reaction

등록일
2017년 3월 21일 09시 51분 32초
접수번호
5216
발표코드
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발표시간
목 10시 : 39분
발표형식
구두발표
발표분야
한국다우케미칼 우수논문상 수상자 구두발표
저자 및
공동저자
사영진, 우진우1, 주상훈1,*
UNIST 화학과, Korea
1UNIST 에너지화학공학부, Korea

Iron- and nitrogen-doped carbon (Fe−N/C) catalysts have emerged as promising nonprecious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) in energy conversion and storage devices. It has been widely suggested that an active site structure for Fe−N/C catalysts contains Fe−Nx coordination. However, the preparation of high-performance Fe−N/C catalysts mostly involves a high-temperature pyrolysis step, which generates not only catalytically active Fe−Nx sites, but also less active large iron-based particles. In this presentation, we present a general “silica-protective-layer-assisted” approach that can preferentially generate the catalytically active Fe−Nx sites in Fe−N/C catalysts while suppressing the formation of less-active large Fe-based particles. The catalyst preparation consisted of an adsorption of iron porphyrin precursor on carbon nanotube (CNT), silica layer overcoating, high-temperature pyrolysis, and silica layer etching, which yielded CNTs coated with thin layer of porphyrinic carbon (CNT/PC) catalysts. Temperature-controlled in situ X-ray absorption spectroscopy during the preparation of CNT/PC catalyst revealed that the coordination of silica layer can stabilize the Fe−N4 sites. The CNT/PC catalyst contained higher density of active Fe−Nx sites compared to the CNT/PC prepared without silica coating. The CNT/PC showed high ORR activity and excellent stability in alkaline media. Importantly, an alkaline anion exchange membrane fuel cell (AEMFC) with a CNT/PC-based cathode exhibited record high performances among NPMC-based AEMFCs. In addition, a CNT/PC-based cathode exhibited a high volumetric current density of 320 A cm−3 in acidic proton exchange membrane fuel cell.


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