Periodic mesoporous organosilica mesophases are versatile precursors for the direct preparation of mesoporous silica/carbon composites, carbon and silicon carbide materials

Abstract

We report the direct preparation of mesoporous silica/carbon composites, mesoporous silica, and nanostructured carbon and silicon carbide materials from mesoporous ethyl-bridged organosilica/surfactant mesophases. Well ordered mesoporous silica/carbon composites, with surface area of ca. 820 m2 g−1 and pore volume of 0.4 cm3 g−1, were obtained via pyrolysis of organosilica mesophases under argon flow at between 800–950 °C. Higher pyrolysis temperature (1100 °C) generated composites with lower porosity. Well ordered mesoporous or super-microporous silicas (with surface area >700 m2 g−1 and pore volume >0.35 cm3 g−1) were readily obtained from calcination (at 550 °C for 8 h in static air) of the silica/carbon composites, while porous carbons (surface area >500 m2 g−1 and pore volume >0.3 cm3 g−1) were generated via silica etching of the composites. The mesoporous silica/carbon composites, mesoporous silica and mesoporous carbon materials retained the particle morphology of the organosilica mesophases. Furthermore, nanostructured and highly crystalline silicon carbide materials with high surface area (380–620 m2 g−1) and pore volume (0.35–0.9 cm3 g−1) were also prepared via pyrolysis of the ethyl-bridged organosilica/surfactant mesophases at suitably high (1300–1350 °C) temperatures followed by calcination in air and silica etching.