Abstract:
A quaternary composite has been synthesized from metal-organic frameworks (MOFs),
one of the widely used precursors for the development of electrode material for
supercapacitors. ZIF-67 template has been synthesized using a typical co-precipitation
method followed by addition of titania in a solvothermal reactor. Three quaternary
composites derived from ZIF-67 pyrolyzed at 700 ℃, 800 ℃ and 900 ℃ are synthesized
using simple co-precipitation method followed by solvothermal reaction. The
morphological analysis revealed a nearly globular morphology for composite prepared at
temperature 900 ℃ (TZ-900). An increased degree of graphitization for carbon in
thesample pyrolyzed at high temperature as confirmed using Raman spectroscopy can be
attributed to better electrochemical performance. Three aqueous electrolytic media are
used to study the electrochemical behavior of the prepared sample comprising 1M KOH,
1M H2SO4, and 1M Na2SO4. The prepared electrodes, TZ-700, TZ-800, and TZ-900
exhibited a specific capacitance of 303, 615, and 1617 F g-1 in the acidic media at 0.5 A g-1. Cyclic stability run for 10,000 cycles with TZ-900 electrode showed a specific capacitance retention of 84% at a current density of 10 A g. X-ray photoelectron spectroscopy and transmission electron microscopy further helped to examine the synergistic effect of metallic cobalt, Co (II), Co (III) and titanium ions in the nanographitic carbon matrix.
