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Superior Electrochemical Properties of Nanofibers Composed of Hollow CoFe 2 O 4 Nanospheres Covered with Onion‐Like Graphitic Carbon
Author(s) -
Hong Young Jun,
Cho Jung Sang,
Kang Yun Chan
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201503357
Subject(s) - kirkendall effect , materials science , nanofiber , electrospinning , carbon nanofiber , chemical engineering , carbon fibers , amorphous carbon , amorphous solid , nanotechnology , electrochemistry , nanoscopic scale , carbon nanotube , electrode , composite material , polymer , metallurgy , chemistry , composite number , organic chemistry , engineering
Nanofibers composed of hollow CoFe 2 O 4 nanospheres covered with onion‐like carbon are prepared by applying nanoscale Kirkendall diffusion to the electrospinning process. Amorphous carbon nanofibers embedded with CoFe 2 @onion‐like carbon nanospheres are prepared by reduction of the electrospun nanofibers. Oxidation of the CoFe 2 ‐C nanofibers at 300 °C under a normal atmosphere produces porous nanofibers composed of hollow CoFe 2 O 4 nanospheres covered with onion‐like carbon. CoFe 2 nanocrystals are transformed into the hollow CoFe 2 O 4 nanospheres during oxidation through a well‐known nanoscale Kirkendall diffusion process. The discharge capacities of the carbon‐free CoFe 2 O 4 nanofibers composed of hollow nanospheres and the nanofibers composed of hollow CoFe 2 O 4 nanospheres covered with onion‐like carbon are 340 and 930 mA h g −1 , respectively, for the 1000th cycle at a current density of 1 A g −1 . The nanofibers composed of hollow CoFe 2 O 4 nanospheres covered with onion‐like carbon exhibit an excellent rate performance even in the absence of conductive materials.