Novel SiOC nanocomposites for high-yield preparation of ultra-large-scale SiC nanowires

Novel SiOC nanocomposites were successfully synthesized from commercial silica sol and sucrose via a simply designed route. The formation of SiOC nanocomposites was studied using thermogravimetry and differential scanning calorimetry. The synthesized nanocomposites were characterized by Fourier transform infrared spectroscopy, x-ray fluorescence spectrometer, x-ray photoelectron spectroscopy, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the synthesized composites are amorphous in nature and homogeneous with the microstructure of close packed SiO₂ and carbon at nanoscale. The SiOC nanocomposites exhibit very high reactivity and can be annealed to produce SiC nanocrystals at 1200 °C which is about 300 °C lower than the value obtained by thermodynamic calculation. Ultra-large-scale β-SiC nanowires with high quality were prepared by directly annealing the synthesized SiOC nanocomposites at 1500 °C under Ar atmosphere, where the yield of SiC nanowires was up to 59%. The SiC nanowires grow along the [111] direction with highly uniform diameters of about 100 nm. Experimental results indicate that the close contact between SiO₂ and carbon at nanoscale plays a vital role in the high yield of SiC nanowires. The present work provides an efficient strategy for the large scale production of high-quality SiC nanowires.