Electrochemical studies of microwave synthesised bimetallic sulfides nanostructures as faradaic electrodes

摘要

A microwave irradiation method has been used to prepare mixed nickel cobalt sulfide (NixCoyS4)nanosheets with different stoichiometric composition as electrodes for electrochemical capacitors. Thisstudy has been undertaken to determine the effect of synthesis time and concentration of nickel on themorphology and pseudocapacitance behavior of the NixCoyS4. It was observed that the time had an effecton the morphology of NixCoyS4, producing sheet-like (leaf-like) morphology which curls inflower-likeshapes with increase in growth (synthesis) time. The effect of morphology on the electrochemicalbehavior was studied by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemicalimpedance spectroscopy (EIS) techniques in aqueous solutions. The sample with a concentration ratio of2:1 of nickel and cobalt (NixCoyS4-3) shows higher faradaic performance when compared to othersamples grown under similar conditions but with different ratios. The maximum specific capacitancevalues obtained for was 1110 F g 1 at a scan rate of 5 mV s 1 for this sample. The Coulombic efficiency ofthe sample was 80% after 2000 galvanostatic charge-discharge cycles at a current density of 5 A g 1.