Formation of Si Nanowires by Direct Electrolytic Reduction of Porous SiO2 Pellets in Molten CaCl2

The effects of starting material and catalyst on the morphology of produced Si have been investigated for the direct electrolytic reduction of porous SiO 2 pellets in molten CaCl 2 at 1123 K. The Si nanowires (SiNWs) were produced using amorphous SiO 2 pellets with a tetrapod-like microstructure as the starting material, whereas plate-like Si was obtained from pellets made of spherical fumed SiO 2 . The SiNWs showed irregular branching and a wide distribution of diameters as the electrolysis proceeded. On the other hand, elongated SiNWs were formed during the electrolysis of pellets comprised of Au nanoparticles (AuNPs) and tetrapod-like microstructured SiO 2 powder. This suggests that AuNPs work as catalysts for longitudinal nanowire growth in the present electrolytic process.