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

Abstract

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.