Study of solvent variation on controlled synthesis of different nanostructured NiCo2O4 thin films for supercapacitive application

Abstract

The present investigation deals with controlled synthesis of nanostructured NiCo2O4 thin films directly on stainless steel substrates by facile and economical chemical bath deposition technique, without adding a surfactant or a binder. The consequences of different compositions of solvents on morphological and electrochemical properties have been studied systematically. We used different solvent composition as Double Distilled Water (DDW), DDW:Ethanol (1:1) and DDW: N, N dimethylformamide (1:1). The films have been named as NCO-W for DDW, NCO-WE for DDW: Ethanol (1:1) solvent and NCO-WD for DDW: N, N dimethylformamide (1:1) solvent. The morphologies of NiCo2O4 thin films modify substantially with change in a solvent. NCO-W exhibited the spikes of Crossandra infundibuliformis like nanostructures. The NCO-WE favored the formation of uniformly distributed leaf-like nanostructure whereas NCO-WD showed randomly oriented nanoplates all over the surface area. The Electrochemical performance of these NiCo2O4 thin films were studied using cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy techniques. The NCO-W, NCO-WE and NCO-WD electrodes showed specific capacitance values of 271, 553 and 140 F/g respectively at the current density of 0.5 mA/cm2 and excellent capacitance retention of 90%, 91% and 80% after 2000 cycles for NCO-W, NCO-WE and NCO-WD samples respectively. This result reveals that NiCo2O4 is a prominent electrode material for supercapacitor application.