Formation of Si nanowires by the electrochemical reduction of porous Ni/SiO2 blocks in molten CaCl2

• Silicon nanowires (SiNWs) are obtained by direct electrolytic reduction of Ni/SiO2 pellets.
• Nano-sized silicon–nickel droplets form at the Ni/SiO2/CaCl2 three-phase interline.
• The growth mechanism of SiNWs has been further investigated.
• The present method may be a potential approach to synthesis nano-sized metal silicides.

Silicon nanowires (SiNWs) were prepared by the electrochemical reduction of solid Ni/SiO2 blocks in molten CaCl2 at 1173 K. The SiNWs have diameter distributions ranging from 80 to 350 nm, and the nickel–silicon droplets are found on the tips of the nanowires. The growth mechanism of SiNWs was investigated, which confirmed that the nano-sized nickel–silicon droplets formed at the Ni/SiO2/CaCl2 three-phase interline. The droplets lead to the oriented growth of SiNWs. Formation of nano-sized nickel–silicon droplets suggests that this method could be a potential way to produce nano-sized metal silicides.