P-Fe bond oxygen reduction catalysts toward high-efficiency metal-air batteries and fuel cells

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-05, Vol.8 (18), p.9121-9127
• Main Authors: Jin, Huihui, Kou, Zongkui, Cai, Weiwei, Zhou, Huang, Ji, Pengxia, Liu, Bingshuai, Radwan, Amr, He, Daping, Mu, Shichun
• Format: Article
• Language: English
• Subjects: Atomic properties; Batteries; Carbon; Catalysts; Electrolytes; Electrolytic cells; Fine structure; Fuel cells; Fuel technology; Iron; Metal air batteries; Oxygen; Phosphorus; Photoelectron spectroscopy; Photoelectrons; Proton exchange membrane fuel cells; Ultrastructure; X ray absorption; X ray photoelectron spectroscopy; Zinc-oxygen batteries
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d0ta02334e

The oxygen reduction activity of carbon-based metal-N catalysts can be effectively regulated by doping with phosphorus (P). However, no attempt has been made to improve the catalyst performance by directly distributing P atoms at the active centers of Fe-N. In this work, P atoms are connected with Fe-N x moieties in the carbon structure to form P-Fe-N x bond by the strong electron coupling effect in a novel C-P-Fe-N x -P-C system (CPFeNPC), verified by extended X-ray absorption fine structure (EXAFS) and X-ray photoelectron spectroscopy (XPS). As a result, it leads to an enhanced oxygen reduction performance with ultrahigh half-wave potentials of 0.923 V and 0.791 V in alkaline and acidic electrolytes, respectively. Significantly, they are far more than that of commercial Pt/C (0.854 V) under alkaline conditions and even almost the same as that of commercial Pt/C (0.807 V) under acidic conditions. Moreover, when adopted as the cathode catalyst, the assembled Zn-air battery (ZAB) and proton-exchange membrane fuel cells (PEMFCs) deliver 1.6-fold and 1.25-fold enhancements in the peak power density compared with that based on commercial Pt/C and conventional Fe-N x -C catalysts, respectively. The developed catalysts with abundant P-coordinated Fe-N x sites shine new light on the real application of metal-N-C catalysts in fuel cells. An Fe, N, P co-doped carbon framework catalyst (CPFeNPC) with a novel C-P-Fe-N x -P-C system exhibits superior oxygen reduction reaction (ORR) catalytic performance and shines new light on the real application of metal-N-C catalysts in fuel cells.