In-situ growth and relevant mechanisms of thick SiC nanowhiskers from hybrid silicon sources

Abstract

SiC nanowhiskers were prepared from photovoltaic silicon waste and quartz sand (as a hybrid silicon source) and coconut fiber (as a carbon source). The phase evolution of the reaction was investigated using X-ray diffraction (XRD) and the microstructure of the product powders was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the temperature range of 1300–1500 °C, SiC whiskers were grown on the surfaces of the carbonized coconut fibers through vapor-solid (VS) mechanism. Above 1100 °C, straight SiC whiskers were also generated in the residual powders by vapor-liquid-solid (VLS) mechanism. The number of SiC whiskers increased significantly with increased reaction temperature. At the optimum reaction temperature of 1500 °C, thick carbon-rich SiC whiskers with straight and dendrite shape covered the whole surface of the carbonized coconut fiber. We have developed a novel, clean, and sustainable method of preparing SiC nanowhiskers. It provides a new way to recycle valuable resources from photovoltaic waste and enables the high-value utilization of agricultural wastes.