Phosphorus induced activity-enhancement of Fe-N-C catalysts for high temperature polymer electrolyte membrane fuel cells

• Published in: Nano research 2023-05, Vol.16 (5), p.6531-6536
• Main Authors: Jin, Xiangrong, Li, Yajie, Sun, Hao, Gao, Xiangxiang, Li, Jiazhan, Lü, Zhi, Liu, Wen, Sun, Xiaoming
• Format: Article
• Language: English
• Subjects: Absorption spectroscopy; Atomic properties; Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Catalysts; Charge density; Chemistry and Materials Science; Condensed Matter Physics; Doping; Electrolytes; Electrolytic cells; Electron microscopy; Fuel cells; Fuel technology; High temperature; Materials Science; Nanotechnology; Noble metals; Phosphoric acid; Poisoning; Polymers; Proton exchange membrane fuel cells; Research Article; X ray absorption; X-ray absorption spectroscopy
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-022-5314-2

Fe-N-C materials with atomically dispersed Fe—N 4 sites could tolerate the poisoning of phosphate, and is regarded as the most promising alternative to costly Pt-based catalysts for the oxygen reduction in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). However, they still face the critical issue of insufficient activity in phosphoric acid. Herein, we demonstrate a P-doping strategy to increase the activity of Fe-N-C catalyst via a feasible one-pot method. X-ray absorption spectroscopy and electron microscopy with atomic resolution indicated that the P atom is bonded with the N in Fe—N 4 site through C atoms. The as prepared Fe-NCP catalyst shows a half-wave potential of 0.75 V (vs. reversible hydrogen electrode (RHE), 0.1 M H 3 PO 4 ), which is 60 and 40 mV higher than that of Fe-NC and commercial Pt/C catalysts, respectively. More importantly, the Fe-NCP catalyst could deliver a peak power density of 357 mW·cm −2 in a high temperature fuel cell (160 °C), exceeding the non-noble-metal catalysts ever reported. The enhancement of activity is attributed to the increasing charge density and poisoning tolerance of Fe—N 4 caused by neighboring P. This work not only promotes the practical application of Fe-N-C materials in HT-PEMFCs, but also provides a feasible P-doping method for regulating the structure of single atom site.