Synthesis and structural evolution of hollow flower-type mesoporous silica microspheres.

Hollow flower-type mesoporous silica microspheres (designated as HFMSs) with tunable smaller pores and lager pores in the shell have been successfully synthesized via a structural difference-based selective etching treatment of solid silica core/mesoporous silica shell (sSiO@mSiO) microspheres. The structure of sSiO@mSiO microspheres could evolve to rattle-type, hollow structure, flower-type structure, and peanut-type structure from core/shell structure just by varying the etching agent from NaCO solution to ammonia solution and adjusting the concentration of etching agent, respectively. Transmission electron microscopy, scanning electron microscopy, and nitrogen adsorption-desorption analysis are applied to characterize the synthesized samples. The mechanism of such a structural evolution is explained in this work. [ABSTRACT FROM AUTHOR]