Journal of Energy Chemistry ›› 2022, Vol. 66 ›› Issue (3): 306-313.DOI: 10.1016/j.jechem.2021.08.019

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Metal-organic framework-derived carbon nanotubes with multi-active Fe-N/Fe sites as a bifunctional electrocatalyst for zinc-air battery

Chao Yanga, Shanshan Shangb, Qinfen Guc, Jin Shangb, Xiao-yan Lia,d,*   

  1. aCentre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China;
    bSchool of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China;
    cAustralian Synchrotron, ANSTO, 800 Blackburn Rd, Clayton, Victoria 3168, Australia;
    dTsinghua-Berkeley Shenzhen Institute, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, Guangdong, China
  • Received:2021-03-02 Revised:2021-07-15 Accepted:2021-08-09 Published:2022-10-25
  • Contact: * E-mail address: xlia@hku.hk (X.-y. Li).

Abstract: Sustainable metal-air batteries demand high-efficiency, environmentally-friendly, and non-precious metal-based electrocatalysts with bifunctionality for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this research, novel functional carbon nanotubes with multi-active sites including well-dispersed single-atom iron throughout the walls and encapsulated ultrafine iron nanoparticles were synthesized as an electrocatalyst (FeNP@Fe-N-C) through one-step pyrolysis of metal-organic frameworks. High-resolution synchrotron powder X-ray diffraction and X-ray absorption spectroscopy were applied to characterize the unique structure of the electrocatalyst. In comparison to the commercial Pt/C and RuO2 electrodes, the newly prepared FeNP@Fe-N-C presented a superb bifunctional performance with its narrow potential difference (Egap) of 0.73 V, which is ascribed to the metallic Fe nanoparticles that boosts the adsorption and activation of oxygen on the active sites with an enhanced O2 adsorption capacity of 7.88 cm3 g-1 and synergistically functionalizes the iron atoms dispersed on the nanotubes. A rechargeable zinc-air battery based on FeNP@Fe-N-C exhibited a superior open-circuit voltage (1.45 V), power density (106.5 mW cm-2), and stable cycling performance. The green technique developed in this work for the fabrication of functional nanotubes raises the prospect of making more efficient electrocatalysts for sustainable energy cells.

Key words: Bifunctional electrocatalyst, Oxygen reduction reaction, Oxygen evolution reaction, Single-atom iron, Encapsulated iron nanoparticles