A General Approach to Preferential Formation of Active Fe–Nx Sites in Fe–N/C Electrocatalysts for Efficient Oxygen Reduction Reaction

• DOI: 10.1021/jacs.6b09470
• Publication Date: 2016-10-18T10:40:56Z
• Authors: Young Jin Sa; Dong-Jun Seo; Jinwoo Woo; Jung Tae Lim; Jae Yeong Cheon; Seung Yong Yang; Jae Myeong Lee; Dongwoo Kang; Tae Joo Shin; Hyeon Suk Shin; Hu Young Jeong; Chul Sung Kim; Min Gyu Kim; Tae-Young Kim; Sang Hoon Joo
• Keywords: Carbon fibers

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