Preparation of AgO hollow porous microsphere via the combination of hard templating, strong electrostatic adsorption and oxidation method and its bactericidal property

Abstract

Hollow architectures have attracted great attention owing to their huge inside space and good performances. In this work, AgO hollow porous microsphere is successfully synthesized through a combination method using low-cost fumed SiO2 nanospheres as a template. Silver diammine ion is adsorbed onto the surface of fumed SiO2 nanospheres via strong electrostatic adsorption, and then converted into AgO@SiO2 composite sphere. The hollow porous structure is obtained by removing SiO2 core through NaOH etching. The removal amount of SiO2 can be controlled by increasing immersion time, resulting in the formation of loose porous shell and the decrease of shell thickness. However, the hollow porous structure is easy to collapse with excessive immersion. After 16 h immersion in NaOH solution, it obtained monoclinic AgO hollow porous sphere with a size of ~1000 nm, a shell thickness of ~200 nm and a BET surface area of 24.50 m2 · g−1. The bactericidal activity of AgO can be significantly improved through such a hollow porous structure. Furthermore, the formation mechanism of AgO hollow porous sphere was elucidated. The combination of strong electrostatic adsorption and removal of SiO2 template with sodium hydroxide is an effective and facile approach for preparing highly active AgO hollow porous microspheres.