Effect of Graphene Oxide Thin Film on Growth and Electrochemical Performance of Hierarchical Zinc Sulfide Nanoweb for Supercapacitor Applications

Surface morphology induced electrical conductivity and specific surface area of a material play a significant role to facilitate electrochemical behavior for supercapacitor application. Therefore, the synthesis step for controlling such parameters becomes very imperative and challenging. Herein, a ZnS nanoweb is deposited directly onto Ni foam with a pre-deposited thin layer of hydrothermally prepared graphene oxide. The structure and surface morphology of the deposited ZnS is observed using XRD and SEM, respectively. The electrical conductivity of the graphene oxide supported ZnS nanoweb, determined using the four probes method, is 100.15 Scm(-1). The specific surface area is 104.42 m(2)g(-1) as determined by BET measurements. Pseudocapacitive behavior is monitored by cyclic voltammetry, and the excellent specific capacity of 3052 Fg(-1) has been found at a scan rate of 2 mVs(-1), while it is 2400.30 Fg(-1) according the galvanostatic charge-discharge profile at a current density of 3 mAcm(-2). Both values are significantly higher than those measured for bare GO or ZnS layers. The energy and power densities of GO supported ZnS nanoweb are determined in a three electrode setup, are 120 WhKg(-1) at 3 mAcm(-2) and 4407.73 Wkg(-1), respectively. In a symmetric two electrode setup, an energy density of 20.29 WhKg(-1) at 2 mAcm(-2) is observed. Hence, both symmetric and asymmetric measurements suggest that GO supported ZnS nanoweb can be applied as a suitable electrode for supercapacitors.