Three-dimensional porous Fe-N-C derived from iron-citrate-functionalized melamine foam as a highly active oxygen reduction catalyst for Zn-air batteries

Jing Liu, Yuanyuan Zhu, Chaohua Fan, Fanglin Du, Luhua Jiang^Z

College of Materials Science and Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao, Shandong 266042, China

Abstract

Herein, we reported a facile strategy to synthesize Fe-N-C catalysts with three dimensional porous structure by employing melamine foam as the self-scarified template, and citrate acid and iron trichloride as the precursors. Scanning electronic micrographs (SEM) and X-ray photoelectron spectroscopy (XPS) were performed to characterize the morphology and chemical valence state of the surface elements of the catalyst. Cyclic voltammetry (CV), liner scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were employed to evaluate the catalytic performance towards the oxygen reduction reaction (ORR). The results show that, the catalyst CA-Fe/MF-N900 (calcinated at 900^oC) displays the best ORR activity and stability. In alkaline electrolyte, the ORR onset potential starts at 0.98V vs. RHE, the half-wave potential at 0.83V vs. RHE, and the limiting current density reaches 5.3 mA cm^-2. After 1000 cycles, the half-wave potential only shifts negatively by 7 mV. The enhanced activity could be attributed to the advanced three-dimensional interconnected porous structure of the Fe-N-C catalyst, which can not only accommodate abundant active sites but also significantly reduce the mass/charge transfer resistance. This work provides a novel preparation route of three-dimensional interconnected porous composites for energy storage and conversion.

Keywords: Oxygen reduction reaction; three-dimensional porous carbon; electrocatalyst

 ^z Email: luhuajiang@qust.edu.cn

DOI: 10.1002/ente.202000149