Excavated Fe-N-C Sites for Enhanced Electrocatalytic Activity in the Oxygen Reduction Reaction

• Published in: ChemSusChem 2014-05, Vol.7 (5), p.1289-1294
• Main Authors: Jeong, Beomgyun, Shin, Dongyoon, Jeon, Hongrae, Ocon, Joey D., Mun, Bongjin Simon, Baik, Jaeyoon, Shin, Hyun-Joon, Lee, Jaeyoung
• Format: Article
• Language: English
• Subjects: Ball milling; Carbon; Carbon - chemistry; Catalysis; electrocatalysts; Electrochemical Techniques; Fuel cells; iron; Iron - chemistry; Microscopy, Electron, Transmission; Nanofibers - chemistry; nanostructures; Nitrogen; Nitrogen - chemistry; Oxidation-Reduction; Oxygen - chemistry; Porosity; reduction; Surface Properties
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201301374

Platinum (Pt) is the best electrocatalyst for the oxygen reduction reaction (ORR) in hydrogen fuel cells, but it is an extremely expensive resource. The successful development of a cost‐effective non‐Pt ORR electrocatalyst will be a breakthrough for the commercialization of hydrogen‐air fuel cells. Ball milling has been used to incorporate metal and nitrogen precursors into micropores of carbon more effectively and in the direct nitrogen‐doping of carbon under highly pressurized nitrogen gas in the process of the preparation of non‐noble ORR catalysts. In this study, we first utilize ball milling to excavate the ORR active sites embedded in Fe‐modified N‐doped carbon nanofibers (Fe‐N‐CNFs) by pulverization. The facile ball‐milling process resulted in a significant enhancement in the ORR activity and the selectivity of the Fe‐N‐CNFs owing to the higher exposure of the metal‐based catalytically active sites. The degree of excavation of the Fe‐based active sites in the Fe‐N‐CNFs for the ORR was investigated with cyclic voltammetry, X‐ray photoelectron spectroscopy, and pore‐size distribution analysis. We believe that this simple approach is useful to improve alternative ORR electrocatalysts up to the level necessary for practical applications. Pt‐free ORR catalyst: Fe‐modified N‐doped carbon nanofibers (Fe‐N‐CNFs) are a promising non‐Pt catalyst for the oxygen reduction reaction (ORR). A pulverization approach to effectively excavate a larger number of active sites embedded in the Fe‐N‐CNFs for the ORR is possible. Facile ball milling results in a significant enhancement in the Fe‐based ORR active sites and the corresponding ORR activity of the Fe‐N‐CNFs.