Bifunctional Oxygen Electrocatalysts Derived from Metal–Organic Framework-Hydrolyzed Nanosheets for Rechargeable Zn-Air Batteries

Abstract

The upsurging interest in rechargeable Zn-air batteries (ZABs) has recently spurred tremendous research effort on exploiting highly efficient and stable bifunctional oxygen electrocatalysts. Herein, we proposed a facile metal–organic framework-hydrolyzed method to fabricate a three-dimensional N-doped carbon nanotube material enriched with FeCo species (FeCo/N-CNT) showing a small potential difference of 0.71 V for oxygen electrocatalytic reactions. When it was used as the air electrode catalyst to assemble the ZAB, high maximum power density (237.5 mW cm–2) and large specific capacity (747.4 mAh g–1) were achieved. More importantly, the corresponding ZABs exhibited high cycling durability with an insignificant voltage gap after the 1300th constant current charge–discharge cycling. Such outstanding rechargeable ZAB performance should originate from FeCo nanoparticles and Fe/Co–N co-doping species integrated into well-graphitized carbon nanotubes. This study offers a novel method to prepare efficient and stable bifunctional oxygen electrocatalysts for rechargeable ZABs.

Progress on Bifunctional Carbon‐Based Electrocatalysts for Rechargeable Zinc–Air Batteries Based on Voltage Difference Performance

“…PA@Z8-Fe-N-C 0.89 1.77 0.89 Gao et al [ 78] Fe/Fe-NC-3 0.87 1.69 0.82 Deng et al [ 91] Co/N-Pg 0.82 1.63 0.81 Tian et al [ 92] Fe-ZIF/OCNT 0.865 1.672 0.807 Sheng et al [ 93] FeCo-N-C 0.81 1.61 0.80 Wu et al [ 94] Co@N-C 0.82 1.58 0.76 Ma et al [ 95] FeNi/NS-C 0.83 1.585 0.755 Li et al [ 96] Mn@Co-NS 0.89 1.61 0.72 Li et al [ 97] FeCo/N-CNT 0.87 1.58 0.71 He et al [ 98] CoNi@CoCN 0.86 1.57 0.71 Zhang et al [ 99] Co/CoFe@NC 0.84 1.54 0.70 Niu et al [ 100] interact with the electrons of sp 2 -C materials through the electron coupling effect, resulting in an activation effect. [86] In the M-N-C catalysts, the N atoms have lone electron pairs, which can form strong interactions with the metal atoms and facilitate the immobilization of metal atom dopants in the carbon skeleton.…”

“…Based on this, an ultrafine bimetallic FeCo-N-C electrocatalyst was designed by Wu et al [94] The catalyst was prepared by a two-step method using imidazolate zeolite skeletons (ZIFs) as intermediates. Compared with two SMCs (Fe-N-C and Co-N-C) synthesized in the same way, FeCo-N-C has an [98] Copyright 2022, American Chemical Society.…”

“…ultra-high ORR/OER electrochemical catalytic performance with a half-wave potential of 0.81 V, E i = 10 of 1.61 V, and ΔE = 0.80 V, which was attributed to its higher degree of graphitization, more active sites of FeCo and the synergic effect between Fe and Co. [94] He et al proposed a 2D MOF derivatization strategy to construct 3D CNTs by combining precursors with bimetallic centers with Fe/Co-N co-dopants and FeCo nanoparticles (FeCo/N-CNT). [98] The 2D MOFs have a large exposed surface area where most of the metal centers are exposed, reducing the number of metal atoms buried in the FeCo/N-CNT derivatives. Figure 11a shows the ORR polarization curves of the optimized FeCo/N-CNT material and the benchmark Pt/C material.…”

Two-Dimensional Atomically Dispersed Co–N/C Oxygen Reaction Electrocatalysts via Molten-Salt-Assisted Pyrolysis of Metal–Organic Frameworks

“…Co–N-doped carbon materials have been acknowledged as one of the most promising candidates because of their many advantages including high electrocatalytic activity, excellent chemical stability, good electrical conductivity, and low cost. − Reports demonstrate that the active parts of this kind of materials are Co–N x moieties anchored in the graphene plane . Notably, such materials involve high-temperature pyrolysis of C, N, and Co-containing precursors, during which Co atoms are mobile and more easily agglomerate into relatively low-activity nanoparticles.…”

Prussian-Blue-Analogue-Derived Ultrathin Co2P-Fe2P Nanosheets for Universal-pH Overall Water Splitting

“…Figure b shows P 2p XPS spectra of NF@CoFeP. The peaks located at 129.3 and 130.1 eV are attributed to metal–P bonds including Fe–P, Co–P, and Ni–P while 134.0 eV originates from P–O bondd in phosphate groups. − The Co 2p XPS spectrum shows six fitting peaks at 782.6, 780.6, 786.0, 795.8, 798.0, and 803.7 eV, respectively ascribed to Co 2+ 2p 3/2 , Co 3+ 2p 3/2 , Co 2p 3/2 satellite, Co 2+ 2p 1/2 , Co 3+ 2p 1/2 , and Co 2p 1/2 satellite (Figure c). − Similarly, Fe 2+ and Fe 3+ are also demonstrated in NF@CoFeP (Figure d). , The Ni 2p XPS spectrum reveals that Ni 0 , Ni 2+ , and Ni 3+ coexist in NF@CoFeP (Figure S7). − The Ni 0 signal should be from the NF substrate, while Ni 2+ and Ni 3+ are due to the presence of Ni 5 P 4 species on NF.…”