Electrodeposition of Ag-doped diamond-like carbon films on stainless steel for supercapacitor applications

Abstract

Diamond-like carbon (DLC) is a class of amorphous carbon materials that possess properties similar to those of diamond, such as high hardness, chemical resistance, and low friction. In this work, DLC films are fabricated using an electrodeposition (ED) method, which is a cost-effective and versatile technique that allows control over the film properties. The DLC films are coated onto stainless steel sheets and used as electrodes for supercapacitors. Here, we introduce the incorporation of silver (Ag) into DLC films to improve the film deposition rate and electrical conductivity. The effects of Ag dopant concentration on the film properties and electrochemical performance are investigated. The deposition rate of the DLC film is enhanced by incorporating AgNO3 into the precursor solution during the electrodeposition process. The incorporation of 1 µM AgNO3 results in the highest deposition rate of DLC. Raman spectroscopy analysis indicates that increasing Ag content in the films promotes the formation of sp3 carbon in the DLC structure. The electrochemical performance of the DLC films is evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) measurements. The results reveal that the presence of Ag induces pseudocapacitive behavior in the stainless steel electrodes, with Ag acting as a catalyst to enhance Fe redox reactions, thereby making the stainless steel advantageous for use in DLC-Ag supercapacitors. The DLC-Ag supercapacitor exhibits a high specific capacitance of up to 5.5 mF/cm2. This superior charge storing capacity is attributed to improved internal resistance and charge transfer, making the Ag-doped DLC supercapacitor a promising candidate for next-generation energy storage devices.