Synthesis of thermally stable porous SiC hollow spheres and control of the shell thickness

• Thermally stable SiC hollow spheres were prepared using SiO2 templates.
• Shell structure of SiC hollow sphere was determined in the template preparation step.
• SiC shell could be prepared at the calcination step.
• The surface areas of the prepared SiC hollow spheres were higher than 770 m2/g.

Thermally stable SiC hollow spheres were prepared using SiO2 templates with two layers. At the calcination at higher than 1300 °C, the SiC hollow sphere could be obtained. The shell thickness of the porous SiC hollow spheres can be controlled by the molar ratio of TMS/TEOS. The pore volumes and BET surface areas of the template SiO2 increased with the molar ratio of TMS/TEOS, while those of the SiC/SiO2 and SiC spheres decreased. It is evident that the pore sizes of the SiC hollow spheres were not influenced by the TMS/TEOS ratio. The wall thickness of the SiC sample increased with an increase in the TMS/TEOS mole ratio. The prepared SiC hollow spheres with the surface area higher than 770 m2/g were thermally stable up to temperatures higher than 700 °C.

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