Issue 48, 2022

Tailoring the MOF structure via ligand optimization afforded a dandelion flower like CoS/Co–Nx/CoNi/NiS catalyst to enhance the ORR/OER in zinc–air batteries

Abstract

Due to their affordability and good catalytic activity for oxygen reactions, MOF-derived carbon composites containing metal alloys have piqued interest. However, during synthesis, MOFs have the disadvantage of causing significant carbon evaporation, resulting in a reduction of active sites and durability. This study proposes tailoring the molecular structure of MOFs by optimizing bipyridine and flexible 4-aminodiacetic terephthalic acid ligands, which have numerous coordination modes and framework structures, resulting in fascinating architectures. MOF frameworks having optimized N and O units are coordinated with Co and Ni ions to provide MOF precursors that are annealed at 700 °C in argon. The MOF-derived Co9S8/Co–Nx/CoNi/Ni3S2@CNS-4 catalyst exhibits excellent catalytic activity, revealing an ORR half-wave potential of 0.86 V and an overpotential (OER) of 196 mV at 10 mA cm−2, a potential gap of 0.72 V and a Tafel slope of 79 mV dec−1. The proposed strategy allows for the rational design of N-coordinated Co and CoNi alloys attached to ultrathin N, S co-doped graphitic carbon sheets to enhance bifunctional activity and sufficient active sites. Consequently, the zinc–air battery using the synthesized catalyst shows a high peak power density of 206.9 mW cm−2 (Pt/C + RuO2 116.1 mW cm−2), a small polarization voltage of 0.96 V after 370 h at 10 mA cm−2, and an outstanding durability of over 2400 cycles (400 h). The key contributions to the superior performance are the synergetic effects of the CoNi alloys plus the N,S-incorporated carbon skeleton, due to the small charge transfer resistances and enhanced active sites of CoNi, metal–S, and pyridinic N.

Graphical abstract: Tailoring the MOF structure via ligand optimization afforded a dandelion flower like CoS/Co–Nx/CoNi/NiS catalyst to enhance the ORR/OER in zinc–air batteries

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
08 Sep 2022
Accepted
06 Nov 2022
First published
07 Nov 2022
This article is Open Access
Creative Commons BY license

Nanoscale, 2022,14, 17908-17920

Tailoring the MOF structure via ligand optimization afforded a dandelion flower like CoS/Co–Nx/CoNi/NiS catalyst to enhance the ORR/OER in zinc–air batteries

M. Gopalakrishnan, M. Etesami, J. Theerthagiri, M. Y. Choi, S. Wannapaiboon, M. T. Nguyen, T. Yonezawa and S. Kheawhom, Nanoscale, 2022, 14, 17908 DOI: 10.1039/D2NR04933C

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