New strategy to prepare hollow silica microspheres with tunable holes on the shell wall

Hollow silica microspheres with holes of tunable numbers and sizes on the shell wall were prepared in this study. Clusters with positively charged polystyrene (PS) microspheres as the central spheres (CSs) and negatively charged PS spheres as the "halo" spheres (HSs) were formed via electrostatic interactions and utilized as a template. In the subsequent silica coating process, only CS was selectively coated; hence, after calcination, porous hollow silica microspheres were obtained.