Growth of high density NiSi/SiC core-shell nanowires by hot-wire chemical vapour deposition for electrochemical applications

In this work, NiSi/SiC core-shell nanowires were grown on crystal silicon and Ni foil substrates by hot-wire chemical vapour deposition technique. The growth of these core-shell nanowires were facilitated by NiSi nanoparticles. These core-shell nanowires were found to be grown at substrate temperatures above 350 °C. The nanowires consisted of single crystalline NiSi and polycrystalline SiC nanocolumn as core and shell nanowires, respectively. Increase of the substrate temperature enhances the growth of high density vertically aligned nanowires. The electrochemical properties of NiSi/SiC core-shell nanowires also have been investigated. The specific capacitance of the NiSi/SiC core-shell nanowires obtained from the cyclic voltammetry curve is about 75 mF/cm2, which is nearly three times higher than the intrinsic NiSi nanowires (21 mF/cm2) and four times higher than the blank Ni foil (17 mF/cm2). The superior electrochemical performances of the nanowire electrode were attributed to the synergetic effects of the core-shell structure and the large specific surface area of the high density vertically aligned nanowires. Moreover, the nanowires grown directly on the Ni foil as a supporting electrode showed to improve their charge transport efficiencies during the electrochemical processes.