期刊
ADVANCED MATERIALS
卷 33, 期 39, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.202006613
关键词
electrocatalysis; fuel cells; M-N-C catalysts; oxygen reduction; single atom catalysts; stability
类别
资金
- National Nature Science Foundation of China [21972051]
- Department of Science and Technology of Guangdong Province [2017ZT07Z479]
- Graduates' Innovation Fund, Huazhong University of Science and Technology [2019ygscxcy031]
- Pico Center at Southern University of Science and Technology (SUSTech) CRF from Presidential fund and Development and Reform Commission of Shenzhen Municipality
An effective strategy is developed to enhance the stability of non-noble-metal catalysts in fuel cells by improving the bonding strength between metal ions and chelating polymers. The optimized catalyst exhibits outstanding activity and stability in both half-cell and fuel cell cathodes, with near 100% retention of current density for an extended period. The study suggests that the Fe-N-4/C site can strongly stabilize Fe centers against demetalation, providing insights for further catalyst design.
An effective and universal strategy is developed to enhance the stability of the non-noble-metal M-N-x/C catalyst in proton exchange membrane fuel cells (PEMFCs) by improving the bonding strength between metal ions and chelating polymers, i.e., poly(acrylic acid) (PAA) homopolymer and poly(acrylic acid-maleic acid) (P(AA-MA)) copolymer with different AA/MA ratios. Mossbauer spectroscopy and X-ray absorption spectroscopy (XAS) reveal that the optimal P(AA-MA)-Fe-N catalyst with a higher Fe3+-polymer binding constant possesses longer Fe-N bonds and exclusive Fe-N-4/C moiety compared to PAA-Fe-N, which consists of approximate to 15% low-coordinated Fe-N-2/N-3 structures. The optimized P(AA-MA)-Fe-N catalyst exhibits outstanding ORR activity and stability in both half-cell and PEMFC cathodes, with the retention rate of current density approaching 100% for the first 37 h at 0.55 V in an H-2-air fuel cell. Density functional theory (DFT) calculations suggest that the Fe-N-4/C site could optimize the difference between the adsorption energy of the Fe atoms on the support (E-ad) and the bulk cohesive energy (E-coh) relative to Fe-N-2/N-3 moieties, thereby strongly stabilizing Fe centers against demetalation.
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