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Atomically Dispersed Fe‐N x /C Electrocatalyst Boosts Oxygen Catalysis via a New Metal‐Organic Polymer Supramolecule Strategy
Author(s) -
Miao Zhengpei,
Wang Xiaoming,
Tsai MengChe,
Jin Qianqian,
Liang Jiashun,
Ma Feng,
Wang Tanyuan,
Zheng Shijian,
Hwang BingJoe,
Huang Yunhui,
Guo Shaojun,
Li Qing
Publication year - 2018
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201801226
Subject(s) - catalysis , materials science , electrocatalyst , scanning transmission electron microscopy , dispersion (optics) , proton exchange membrane fuel cell , metal , passivation , chemical engineering , polymer , metal organic framework , inorganic chemistry , nanotechnology , electrode , transmission electron microscopy , chemistry , electrochemistry , organic chemistry , adsorption , composite material , physics , layer (electronics) , optics , engineering , metallurgy
The development of high‐performance oxygen reduction reaction (ORR) catalysts derived from non‐Pt group metals (non‐PGMs) is urgent for the wide applications of proton exchange membrane fuel cells (PEMFCs). In this work, a facile and cost‐efficient supramolecular route is developed for making non‐PGM ORR catalyst with atomically dispersed Fe‐N x /C sites through pyrolyzing the metal‐organic polymer coordinative hydrogel formed between Fe 3+ and α‐L‐guluronate blocks of sodium alginate (SA). High‐angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and X‐ray absorption spectroscopy (XAS) verify that Fe atoms achieve atomic‐level dispersion on the obtained SA‐Fe‐N nanosheets and a possible fourfold coordination with N atoms. The best‐performing SA‐Fe‐N catalyst exhibits excellent ORR activity with half‐wave potential ( E 1/2 ) of 0.812 and 0.910 V versus the reversible hydrogen electrode (RHE) in 0.5 m H 2 SO 4 and 0.1 m KOH, respectively, along with respectable durability. Such performance surpasses that of most reported non‐PGM ORR catalysts. Density functional theory calculations suggest that the relieved passivation effect of OH* on Fe‐N 4 /C structure leads to its superior ORR activity to Pt/C in alkaline solution. The work demonstrates a novel strategy for developing high‐performance non‐PGM ORR electrocatalysts with atomically dispersed and stable M‐N x coordination sites in both acidic and alkaline media.