Given these advantages of widely designable structures and environmentally friendly characteristics, organic electrode materials (OEMs) are considered to be promising electrode materials for alkaline metal-ion batteries. However, their large-scale application is hampered by insufficient specific capacity and rate performance. Here, Fe 2 + is coupled to the anhydride molecule NTCDA to form a novel K-storage anode Fe-NTCDA. In this way, the working potential of Fe-NTCDA anode is reduced, which makes it more suitable to be used as an anode material. Meanwhile, the electrochemical performance is significantly improved due to the increase in K-storage sites. Moreover, electrolytes regulation is implemented to optimize the K-storage behavior, resulting into a high specific capacity of 167 mAh/g after 100 cycles at 50 mA/g and 114 mAh/g even at 500 mA/g in the 3 M KFSI/ DME electrolytes.
Dopant-free
defective carbon electrocatalysts have been considered
as promising alternatives to traditional precious metal electrocatalysts
recently. Compared with precious metal catalysts and transition-metal
catalysts, since there are no metals doped, electrochemical devices
assembled with dopant-free defective carbons are free from environmental
pollution and subsequent recovery problems. In order to obtain abundant
carbon defects with high-intrinsic catalytic activity, the synthesis
of dopant-free defective carbons requires complex and harsh preparation
conditions. Therefore, the construction of active defects with efficient
utilization, especially through a simple process, is still a great
challenge for the development of dopant-free defective carbon electrocatalysts.
Herein, dissolution–recrystallization strategy was employed
to design Zn-MOF-74 precursors for the synthesis of dopant-free defective
carbons, realizing the synchronous manipulation of high ratio of carbon
defects and highly exposed mass transfer channels. One-dimensional
porous defective carbon nanorods (d-CNRs), which exhibited excellent
oxygen reduction reaction (ORR), electrocatalytic activity, and molecular
selectivity, were synthesized by directly carbonizing rodlike Zn-MOF-74
precursors. Attributed to the dissolution–recrystallization
strategy, with the activation of in situ-formed ZnO, the synthesized
d-CNRs exhibited unique pore–crack nested porous structures,
which carried abundant defects as activity sites for ORR and showed
a surprisingly high specific surface area of 2459 m2/g
with a high ratio of mesopores. d-CNRs also showed promising applications
in Zn–air batteries with a stable long-term discharge of no
obvious voltage drop after 60 h. The dissolution–recrystallization
strategy provided a simple controllable pathway for the efficient
construction of dopant-free defective carbon electrocatalysts.
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