Effect of Electrolyte Type on Properties of Diamond - like Carbon Films Electrodeposited onto N-Type Si Substrate, Application as Electrode for Supercapacitors

Abstract

In this work, diamond-like carbon (DLC) thin films were successfully electrodeposited onto n-type Si(100) substrate using three types of organic electrolyte (as carbon precursor) namely dimethylsulfoxide (C₂H₆OS), acetonitrile (CH₃CN) and ethanol (CH₂CH₂OH). The effect of electrolyte type on morphological, structural and chemical properties was investigated using Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray and X-ray diffraction (XRD). The DLC films Raman spectra show the films are amorphous and the more disorder film is obtained by dimethylsulfoxide (DMSO). These results were confirmed by energy dispersive X-ray and XRD techniques. The SEM observations show that the DLC films were uniformly deposited on the whole Si substrate surface and that it contains of compact and small spherical grains with uniform distribution. Moreover, it was found that the DLC film obtained from a DMSO electrolyte is more conductive, which enables it to be more favorable for the fabrication of a good supercapacitor electrode. The study of electrochemical properties of Si and DLC/Si electrode has shown that the deposition of DLC films from DMSO electrolyte remarkably improves the electrochemical activity of Si electrode and the specific capacitance. Indeed, it allows to get a specific capacitance of 17 mF/cm² in KOH aqueous solution at scan rate of 5 mV/s with capacitance retention of 95% after 4000 cycles. Thus, the deposition of DLC film from DMSO electrolyte onto silicon substrate can be considered as a simple and economical method to fabricate of a performant electrode of supercapacitors.