In situ hydrothermal preparation of mesoporous Fe3O4 film for high- performance negative electrodes of supercapacitors

A mesoporous Fe3O4 film was prepared as binder-free electrode material for supercapacitors through a facile process that included the hydrothermal electroplating of an Fe/Zn alloy, in situ electrolytic dealloying to remove the Zn template, and oxidation in a water vapor environment. The Fe3O4 film showed a cubic structure and mesoporosity with a specific surface area of 247 m(2) g(-1). As a negative electrode material, the mesoporous Fe3O4 film delivered a high gravimetric capacity of 221 C g(-1) at 1 A g(-1), and the gravimetric capacity was maintained at 154 C g(-1) even at a high current density of 50 A g(-1). In addition, the mesoporous Fe3O4 electrode exhibited very high cycling stability (only 4.7% capacity loss after 10,000 galvanostatic charge-discharge cycles). Electrochemical impedance spectroscopy revealed that the mesoporous Fe3O4 film had excellent conductivity, implying its promising application as a supercapacitor electrode.