Synthesis of cubic type hollow silica particles

Abstract

Cubic-type hollow silica particles were prepared from Fe 2O 3–SiO 2 core-shell composite particles by selectively leaching the iron oxide core materials using acidic solution. The cubic Fe 2O 3 core particles were obtained by the hydrolysis reaction of iron salts. The Fe 2O 3–SiO 2 core-shell type particles were prepared by the deposition of a SiO 2 layer onto the surface of Fe 2O 3 particles using a two-step coating process. The first step involved primary coating with sodium silicate solution followed by subsequent coating by controlled hydrolysis of tetraethoxysilicate (TEOS). The core Fe 2O 3 was removed by dissolution in an acidic solution which gave rise to the hollow type silica particles. Scanning electron microscopic observation clearly revealed that the morphology is closely related to those of core the Fe 2O 3 particles. The cross sectional view determined by transmission electron microscopy revealed a silica shell with a thickness of about 50 nm. The porous texture of the hollow type silica particles is further characterized by nitrogen adsorption–desorption isotherm measurements.