Development of a highly active Fe–N–C catalyst with the preferential formation of atomic iron sites for oxygen reduction in alkaline and acidic electrolytes

Asad Mehmood, Basit Ali, Mengjun Gong, Min Gyu Kim, Ji Young Kim, Jee Hwan Bae, Anthony Kucernak, Yong Mook Kang, Kyung Wan Nam

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Nitrogen-doped porous carbons containing atomically dispersed iron are prime candidates for substituting platinum-based catalysts for oxygen reduction reaction (ORR) in fuel cells. These carbon catalysts are classically synthesized via complicated routes involving multiple heat-treatment steps to form the desired Fe-Nx sites. We herein developed a highly active Fe–N–C catalyst comprising of exclusive Fe-Nx sites by a simplified solid-state synthesis protocol involving only a single heat-treatment. Imidazole is pyrolyzed in the presence of an inorganic salt-melt resulting in highly porous carbon sheets decorated with abundant Fe-Nx centers, which yielded a high density of electrochemically accessible active sites (1.36 × 1019 sites g−1) as determined by the in situ nitrite stripping technique. The optimized catalyst delivered a remarkable ORR activity with a half-wave potential (E1/2) of 0.905 VRHE in alkaline electrolyte surpassing the benchmark Pt catalyst by 55 mV. In acidic electrolyte, an E1/2 of 0.760 VRHE is achieved at a low loading level (0.29 mg cm−2). In PEMFC tests, a current density of 2.3 mA cm−2 is achieved at 0.90 ViR-free under H2–O2 conditions, reflecting high kinetic activity of the optimized catalyst.

Original languageEnglish
Pages (from-to)148-157
Number of pages10
JournalJournal of Colloid and Interface Science
Volume596
DOIs
StatePublished - 15 Aug 2021

Keywords

  • Fe–N–C
  • Fuel cells
  • Non-precious metal catalysts
  • Oxygen reduction reaction
  • Site density

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