Abstract:
Metal-organic frameworks (MOFs) have been reported as promising electrode materials
for high performance supercapacitors. Significant research has been conducted to prepare
MOF composites using conductive additives such as graphene nanosheets. Furthermore,
conductive redox-active metals such as Copper and Cobalt have also been incorporated
into MOF structures to boost up the electrochemical performance. However, in this work
we used graphene nanosheets to influence the crystallization and growth of iron-MOFs
followed by the washing away of graphene. This in-situ synthesis protocol was carried out
via a facile hydrothermal approach. Later, the conductive Copper was also added into the
MOF to investigate its influence on the performance of electrode material. The synthesized
materials (i.e., Fe-MOF, Fe-MOF/G, and FeCu-MOF/G) were tested against their
electrochemical performance using a tri-electrode electrochemical system in 1M KOH
solution. These MOF samples were characterized using X-ray diffraction (XRD), Scanning
electron microscopy (SEM), Fourier transform infrared (FTIR) and Raman spectroscopy.
The electrochemical properties of the prepared samples were analysed using cyclic
voltammetry (CV), galvanostatic charge and discharge (GCD), and electrochemical
impedance spectroscopy (EIS). The in-situ growth of iron-MOFs using graphene resulted
in enhanced specific capacitance and higher charge/discharge stability which validates the
superiority of this in-situ synthesis approach.
One of the developed electrode materials, FeCu-MOF/G, displayed a high specific
capacitance of 1132 Fg−1
at current density of 3 A g
−1
. Moreover, FeCu-MOF/G also
showed a cyclic charge/ discharge stability of 85% for 6000 cycles at 10 A g−1
. The
exceptional performance displayed by the developed MOFs in the presence of graphene
are highlighted their potential as appropriate electrode materials for supercapacitors.
The in-situ growth of iron-MOFs using graphene resulted in enhanced specific capacitance
and higher charge/discharge stability which validates the superiority of this in-situ
synthesis approach.
