Sub-50 nm Iron-Nitrogen-Doped Hollow Carbon Sphere-Encapsulated Iron Carbide Nanoparticles as Efficient Oxygen Reduction Catalysts

Haibo Tan; Yunqi Li; Jeonghun Kim; Toshiaki Takei; Zhongli Wang; Xingtao Xu; Jie Wang; Yoshio Bando; Yong-Mook Kang; Jing Tang; Yusuke Yamauchi

doi:10.1002/advs.201800120

Sub-50 nm Iron-Nitrogen-Doped Hollow Carbon Sphere-Encapsulated Iron Carbide Nanoparticles as Efficient Oxygen Reduction Catalysts

Adv Sci (Weinh). 2018 May 12;5(7):1800120. doi: 10.1002/advs.201800120. eCollection 2018 Jul.

Authors

Haibo Tan^{1

2

3}, Yunqi Li^{1

4}, Jeonghun Kim⁵, Toshiaki Takei¹, Zhongli Wang¹, Xingtao Xu¹, Jie Wang¹, Yoshio Bando^{1

6}, Yong-Mook Kang⁷, Jing Tang¹, Yusuke Yamauchi^{2

3

5

8}

Affiliations

¹ International Center for Materials Nanoarchitectonics (WPI-MANA) National Institute for Materials Science (NIMS) 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan.
² College of Chemistry and Molecular Engineering Qingdao University of Science and Technology Qingdao 266042 China.
³ Faculty of Science and Engineering Waseda University 3-4-1 Okubo Shinjuku Tokyo 169-8555 Japan.
⁴ Department of Automotive Engineering School of Transportation Science and Engineering Beihang University Beijing 100191 P. R. China.
⁵ School of Chemical Engineering & Australian Institute for Bioengineering and Nanotechnology (AIBN) The University of Queensland Brisbane QLD 4072 Australia.
⁶ Australian Institute for Innovative Materials (AIIM) University of Wollongong North Wollongong NSW 2500 Australia.
⁷ Department of Energy and Materials Engineering Dongguk University-Seoul Seoul 04620 South Korea.
⁸ Department of Plant & Environmental New Resources Kyung Hee University 1732 Deogyeong-daero, Giheung-gu Yongin-si Gyeonggi-do 446-701 South Korea.

Abstract

Sub-50 nm iron-nitrogen-doped hollow carbon sphere-encapsulated iron carbide nanoparticles (Fe₃C-Fe,N/C) are synthesized by using a triblock copolymer of poly(styrene-b-2-vinylpyridine-b-ethylene oxide) as a soft template. Their typical features, including a large surface area (879.5 m² g^-1), small hollow size (≈16 nm), and nitrogen-doped mesoporous carbon shell, and encapsulated Fe₃C nanoparticles generate a highly active oxygen reduction reaction (ORR) performance. Fe₃C-Fe,N/C hollow spheres exhibit an ORR performance comparable to that of commercially available 20 wt% Pt/C in alkaline electrolyte, with a similar half-wave potential, an electron transfer number close to 4, and lower H₂O₂ yield of less than 5%. It also shows noticeable ORR catalytic activity under acidic conditions, with a high half-wave potential of 0.714 V, which is only 59 mV lower than that of 20 wt% Pt/C. Moreover, Fe₃C-Fe,N/C has remarkable long-term durability and tolerance to methanol poisoning, exceeding Pt/C regardless of the electrolyte.

Keywords: hollow carbon; iron carbide; nitrogen doping; oxygen reduction reaction; triblock copolymer templates.