Co3Fe7/CoCx nanoparticles encapsulated in nitrogen-doped carbon nanotubes synergistically promote the oxygen reduction reaction in Zn-air batteries

Lang Xiao; Wanqing Yu; Jing Liu; Shankui Luan; Wenyu Pei; Xuejing Cui; Luhua Jiang

doi:10.1016/j.jcis.2023.11.034

Co₃Fe₇/CoC_x nanoparticles encapsulated in nitrogen-doped carbon nanotubes synergistically promote the oxygen reduction reaction in Zn-air batteries

J Colloid Interface Sci. 2024 Feb:655:427-438. doi: 10.1016/j.jcis.2023.11.034. Epub 2023 Nov 7.

Authors

Lang Xiao¹, Wanqing Yu¹, Jing Liu², Shankui Luan¹, Wenyu Pei¹, Xuejing Cui¹, Luhua Jiang³

Affiliations

¹ College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China.
² College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China. Electronic address: liuj955@qust.edu.cn.
³ College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China. Electronic address: luhuajiang@qust.edu.cn.

PMID: 37951000
DOI: 10.1016/j.jcis.2023.11.034

Abstract

Efficient and stable non-precious metal catalysts (NPMCs) for the oxygen reduction reaction (ORR) are crucial for the advancement of Zn-air batteries. Herein, we report a supramolecular self-scarifying template and confinement pyrolysis strategy to obtain an efficient ORR catalyst of well-dispersed Co₃Fe₇/CoC_x heterostructure nanoparticles encapsulated by nitrogen-doped carbon nanotubes (Co₃Fe₇/CoC_x@N-CNT). The as-synthesized Co₃Fe₇/CoC_x@N-CNT catalyst exhibited outstanding ORR activity, with a half-wave potential of 0.88 V versus a reversible hydrogen electrode, and good stability. The Zn-air battery based on the Co₃Fe₇/CoC_x@N-CNT cathode achieved a peak power density of 265 mW cm^-2 and a durability of over 200 h, which is superior to most reported NPMCs and even the Pt/C counterpart. The physical characterization and electrochemical poisoning experiments revealed that the Co₃Fe₇/CoC_x nanoparticles in the core along with pyridine N and Fe-N_x hosted in the carbon nanotube all acted as active sites for the ORR. Further theoretical calculations showed that the charge redistribution between the Co₃Fe₇/CoC_x nanoparticles and the Fe-N_x carbon overlayers downshifted the d-band center of Fe and optimized the adsorption ability, which boosted the ORR kinetics. This work provides an effective strategy to synthesize non-precious metal ORR catalysts with multiple active sites and highlights the synergistic role of encapsulated nanoparticles and carbon support.

Keywords: Confined pyrolysis; Heterostructure; Oxygen reduction reaction; Synergistic catalysis; Zn-air battery.