In situ Fabrication of Tugnsten Disulfide on Copper Foam for Application as Electrodes in Supercapacitors by Reactive Sputtering Technique.

Tungsten disulfide, owing to its high theoretical specific capacitance is one of the most studied and promising candidates for electrochemical energy storage applications among various layered materials. Herein, we have fabricated WS2 thin films on silicon substrates by using reactive DC magnetron sputtering technique with metallic tungsten target and H2S as sulfur source at room temperature (Ar:H2S 2:1). For electrochemical application, the electrodes have been prepared in-situ using copper foam as current collector. The in-situ growth allows the films to form actively structured electrodes as well as provide an opportunity to study the morphological effect of electrodes on electrochemical performance. The morphological results depicted the growth of grainy WS2 thin films on current collector with an average roughness of 2.7 nm. Further, we have performed detailed electrochemical analysis and studied the supercapacitive properties of tungsten disulfide. We found the electric double layer capacitance of WS2 thin films to be 2.42 mF/cm² with linear charge discharge characteristics. This high areal capacitance of WS2 thin films may be attributed to the contribution of metallic foam current collector which reduces the global equivalent series resistance of electrode-electrolyte system. Additionally, copper foam functions as a mechanical backbone and improves the charge carrier transport across the electrode. [ABSTRACT FROM AUTHOR]