Spray Pyrolysis Regulated FeCo Alloy Anchoring on Nitrogen–Doped Carbon Hollow Spheres Boost the Performance of Zinc–Air Batteries

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-06, Vol.20 (23), p.e2310318-n/a
• Main Authors: Huang, Hongrui, Liang, Qianqian, Guo, Huajun, Wang, Zhixing, Yan, Guochun, Wu, Feixiang, Wang, Jiexi
• Format: Article
• Language: English
• Subjects: bifunctional catalyst; bimetallic alloy; Binary alloys; Carbon; Catalysts; Chemical reduction; core–shell structure; Defects; Ferrous alloys; High temperature; Iron; Metal air batteries; Metal oxides; metal–organic frameworks; Nitrogen; Oxygen evolution reactions; Oxygen reduction reactions; Rechargeable batteries; Spray pyrolysis; Substrates; ultrasonic spray pyrolysis; Zinc-oxygen batteries
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202310318

Low‐cost and high‐efficiency non‐precious metal‐based oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional catalysts are the key to promoting the commercial application of metal–air batteries. Herein, a highly efficient catalyst of Fe0.18Co0.82 alloy anchoring on the nitrogen‐doped porous carbon hollow sphere (FexCo1‐x/N‐C) is intelligently designed by spray pyrolysis (SP). The zinc in the SP‐derived metal oxides and metal‐organic framework volatilize at high temperature to construct a hierarchical porous structure with abundant defects and fully exposes the FeCo nanoparticles which uniformly anchor on the carbon substrate. In this structure, the coexistence of Fe0.18Co0.82 alloy and binary metal active sites (Fe‐Nx/Co‐Nx) guarantees the Fe0.2Co0.8/N‐C catalyst exhibiting an excellent half‐wave potential (E1/2 ═ 0.84 V) superior to 20% Pt/C for ORR and a suppressed overpotential (280 mV) than RuO2 for OER. Assembled rechargeable Zn–air battery (RZAB) demonstrates a promising specific capacity of 807.02 mAh g−1, peak power density of 159.08 mW cm−2 and durability without electrolyte circulation (550 h). This work proposes the design concept of utilizing an oxide core to in situ consume the porous carbon shell for anchoring metal active sites and construct defects, which benefits from spray pyrolysis in achieving precise control of the alloy structure and mass preparation. Benefiting from the uniformity and rapid prototyping of spray pyrolysis, mass production and functional customization of material with high specific surface and abundant carbon defects are achievable through in situ doping and etching metal‐organic framework‐derived carbon shells with oxide cores. The active sites of Fe‐N, Co‐N, and Fe0.18Co0.82 alloy synergistically facilitates the exceptional bifunctional catalytic activity of Fe0.2Co0.8/N‐C.