A facile route to prepare high surface area mesoporous SiC from SiO2 sphere templates

Abstract

A simple and economic process for the preparation of mesoporous SiC ceramics with high BET surface area was developed by using commercially available sources. Low viscosity polycarbosilane as a SiC precursor was infiltrated into a sacrificial silica sphere template, which was precipitated by the centrifugation of an aqueous silica sol having a particle diameter in the range 20–100 nm. It was subsequently etched off by aqueous HF after pyrolysis in an argon atmosphere at 1000–1400 °C. The mesoporous SiC prepared from 20–30 nm aqueous silica sol exhibited a significantly high surface area of 612.7 m² g⁻¹ (pore volume 0.81 cm³ g⁻¹), with a bimodal pore size distribution. The pore characteristics of various mesoporous SiC ceramics were investigated by controlling the diameter of colloidal silica sols and pyrolytic temperatures. In addition, it was demonstrated that mesoporous SiC patterns with a 20 µm width could be fabricated on a Si wafer using a micromolding in capillaries (MIMIC) method as one of the soft lithography techniques. Finally, the prepared mesoporous SiC products were thoroughly analyzed using SEM, TEM, nitrogen adsorption isotherms and XRD.