Synthesis and characterization of silica nanoparticles preparing by low-temperature vapor-phase hydrolysis of SiCl ₄

An economical and environmentally benign method is proposed for the preparation of silica nanoparticles by hydrolysis of silicon tetrachloride vapor with water vapor at a low temperature (∼150 °C). Analysis by X-ray fluorescence, X-ray diffraction, and scanning electron microscopy, and examination of nanoparticle size distribution, specific surface area, and pore diameter revealed that dry processing was more suitable than wet processing for collection of nanoparticles. The porous amorphous silica had high purity (99.89 wt % SiO ₂), large specific surface area (342.44 m ²/g), and a size distribution (162.8 ± 41.0 nm, polydispersity index = 0.221), and was prepared at a reaction temperature of 150 °C and reaction time of 5 s. The thermal stability of the silica nanoparticles was verified by demonstrating that calcination at temperatures ≤ 600 °C could remove surface hydroxyl groups, achieving hydrophobic modification, while maintaining particle mesostructure. The reduced cost of the synthesis route presented here is a result of the low reaction temperature and the inexpensive materials used in the process, making this a promising method for wide use in various high-end applications.