Synthesis and formation mechanism of porous silicon carbide stacked by nanoparticles from precipitated silica/glucose composites

Porous silicon carbide (SiC) with a Brunauer–Emmett–Teller specific surface area of 75 m² g⁻¹ and a pore volume of 0.37 cm³ g⁻¹ was synthesized through a facile process using industrial precipitated silica and glucose. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses indicated that the SiC was stacked by β-SiC nanoparticles with size ranging from 60 to 150 nm, and its morphology was similar to that of precipitated silica. Further analysis showed that the formation mechanism of porous SiC was different from the general carbothermal reduction method. The proposed mechanism indicated that precipitated silica is a porous particle stacked by amorphous primary silica nanoparticles. When the temperature was higher than its softening point during the carbothermal reduction reaction, the silica nanoparticles softened and began to change from solid phase to liquid phase with a certain viscosity. Then, the pyrolytic carbon of glucose in contact with silica nanoparticles was diffused into the liquid phase and reacted in situ to form SiC. Precipitated silica served as a template, and SiC inherited its morphology and structure.