Abstract:
A microwave irradiation method has been used to prepare mixed nickel cobalt sulfide (NixCoyS4)
nanosheets with different stoichiometric composition as electrodes for electrochemical capacitors. This
study has been undertaken to determine the effect of synthesis time and concentration of nickel on the
morphology and pseudocapacitance behavior of the NixCoyS4. It was observed that the time had an effect
on the morphology of NixCoyS4, producing sheet-like (leaf-like) morphology which curls in
flower-like
shapes with increase in growth (synthesis) time. The effect of morphology on the electrochemical
behavior was studied by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical
impedance spectroscopy (EIS) techniques in aqueous solutions. The sample with a concentration ratio of
2:1 of nickel and cobalt (NixCoyS4-3) shows higher faradaic performance when compared to other
samples grown under similar conditions but with different ratios. The maximum specific capacitance
values obtained for was 1110 F g 1 at a scan rate of 5 mV s 1 for this sample. The Coulombic efficiency of
the sample was
80% after 2000 galvanostatic charge-discharge cycles at a current density of 5 A g 1.
