Diamond-Like Carbon - Coated Silicon Nanowires as a Supercapacitor Electrode in an Aqueous LiClO4 Electrolyte

Silicon nanowires (SiNWs) were successfully coated by uniform, adherent, and homogenous films of diamond-like carbon (DLC) using electrophoretic method. The coating was performed in an organic dimethylsulfoxide (DMSO) solution at 70 degrees C for 60 min with an applied voltage of 150 V. The as prepared samples of SiNWs and DLC/SiNWs were characterized by a scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and Raman spectroscopy techniques. The SEM micrographics showed that the films were uniformly deposited on the whole of SiNWs surface and composed of compact and small spherical grains with uniform distribution. Raman spectroscopy indicates that the coating films were DLC in nature. These results were well confirmed by the EDX and XRD techniques. The electrochemical investigation including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy, showed that the electrochemical behavior of SiNWs was clearly enhanced after coating with a DLC film. Indeed, the latter showed a specific capacitance of 400 mF/cm(2) at scan rate of 5 mV/s in an aqueous 0.5 M LiClO4 solution with capacitance retention of 90% after 16.000 cycles. Thus, the deposition of DLC film onto silicon nanowires (SiNWs) substrate can be considered as a simple and economical method to fabricate a high-performance electrode for supercapacitors.