Epitaxial growth of MnFe2O4 nanosheets arrays for supercapacitor

Abstract

Due to its isotropic growth habit, preparation of well-defined MnFe2O4 arrays is still a great challenge. In this paper, the MnFe2O4 nanosheets arrays (MFONSAs) have been successfully fabricated on Ni foam (NF) by immersing the NF into the precursor solution and subsequent hydrothermal treatment. According to the results of the control experiments, the pH value of precursor solution has significant effect on the formation of MFONSAs. When the pH is 13, a layer of Ni(OH)2 nanoarrays will be grown on the surface of NF during the immersion process by in situ etching. The (404) and (311) facets of MnFe2O4 will be subsequently growth along with the (111) and (101) facets of Ni(OH)2 seeds by epitaxial growth in the following hydrothermal treatment and well-defined MFONSAs can be obtained. When evaluated as a supercapacitor electrode, the as-prepared MFONSAs exhibit an ultrahigh specific capacity of 302.6 mC cm−2 under the current density of 1 mA cm−2. Furthermore, the asymmetric supercapacitors (ASCs) based on as-obtained MFONSAs cathode and actived carbon (AC) anode displayed an excellent electrochemical behavior with a high energy density of 68.7 mWh cm−2 at 587 mW cm−2 and superior cyclic stability. For a practical application test, a light-emitting diode was immuinated for 50 s by an ASC with only charged 10 s, which demonstrated a potential electrode material in supercapacitor.