Influence of the pH on the Morphology of Sol-Gel-Derived Nanostructured SiC

This investigation deals with the use of the carbothermal reduction reaction of carbonaceous silica xerogel for synthesizing nanostructured SiC. The effect of the pH of the early-prepared gel (EPG) on the properties of the finally obtained nanostructured silicon carbide was investigated. The produced silicon carbide samples were characterized by X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy, and N(2) porosimetry. The results revealed that the variation of EPG pH greatly affected the structural properties of the finally obtained nanostructured silicon carbide. The morphology of the produced nanostructured silicon carbide was changed from nanoparticles to nanorods and vice versa with changing the pH values of the gel. The nitrogen adsorption-desorption isotherms of the samples are of classical type IV, characteristic of mesoporous materials. The BET surface areas of the nanostructured silicon carbide are increased from 68 to 106 m2/g with increasing the pH of the EPG from 3 to 5, respectively.