Synthesis of Silicon Carbide Nanowires from a Hybrid of Amorphous Biopolymer and Sol-Gel-Derived Silica

We report here the formation of silicon carbide (SiC) nanowires from inorganic-organic hybrid of sol-gel-derived silica and the commercially available lignin that is naturally abundant amorphous biopolymer. This organic-inorganic hybrid material in the absence of catalyst was carbothermally reduced for a period of 1 h at 1400 degrees C in inert atmosphere followed by oxidization. The nanostructures were characterized by scanning electron microscopy and high resolution scanning electron microscopy, which show the continuous formation of beta-SiC nanowires in the range of 50-200 nm diameter and length of few micrometers. Transmission electron microscopy revealed Y-shaped structures (branched) of the nanowires grown in the direction of parallel to the [100] plane having two heads and one leg. The nanowires were formed with joints that were formed at regular intervals as circular rings. The deposition of silica layer on the outer surface of the nanowires was also observed. According to the X-ray diffraction pattern, peaks at 2 theta=35.9 degrees and 59.8 degrees indicate the formation of beta-SiC and a sharp peak at 2 theta=22.1 degrees suggests the presence of unreacted crystalline silica (crystoballite). The Raman shifts for beta-SiC appeared as small peaks at 795.6 and 983.1 cm-1, respectively. The characteristic vibration of SiC at 795 cm-1 in Fourier transform infrared spectroscopy was also observed.