Synthesis of monolithic mesoporous silicon carbide from resorcinol-formaldehyde/silica composites

Resorcinol-formaldehyde/silica composite (RF/SiO₂) gels were synthesized in one pot using a facile process. RF/SiO₂ aerogels were obtained after supercritical carbon dioxide fluid drying. Monolithic mesoporous silicon carbide (SiC aerogels) was prepared from RF/SiO₂ aerogels after carbothermal reduction and calcination. The as-prepared SiC products exhibited monolithic mesoporous morphology and possessed a BET specific surface area of 251 m²/g and a pore volume of 0.965 cm³/g. X-ray diffraction (XRD) and transmission electron microscopy (TEM) demonstrated that the resulting SiC aerogels were composed of α-SiC nanocrystals. The bulk density and skeleton density of SiC products is 0.288 g/cm³ and 3.12 g/cm³, respectively. The porosity of SiC products is 90.8%. The SiC aerogels were stable up to temperatures near 650 °C.