Synthesis and characterization of silicon carbide nanowires from lignin-phenolic resin and silicon powder with an in-situ formed molten salt as catalyst

Silicon carbide (SiC) nanowires were synthesized using lignin-phenolic resin (LPR) and silicon powder as raw materials. The morphology and structures of the nanowires were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The influence of reaction conditions on the growth of the nanowires was investigated by thermodynamic analysis. It was revealed that the growth of the nanowires starts at around 1 100 °C by a vapor-liquid-solid (VLS) mechanism and the growth temperature is lower than that for the formation of SiC nanowires from commercial phenolic resin and silicon powder. The nanowires have diameters of 30-100 nm and lengths of several microns. It was revealed that the inorganic salts are formed in-situ from LPR in the lignin segment as liquid catalyst droplets during pyrolysis. These dissolve SiC and become supersaturated, from which SiC nanowires grow along the [1 1 1] direction by the stacking of (1 1 1) planes.