One-step strategy for synthesis of yolk-shell silica spheres using trisiloxane-tailed ionic liquids as a template

Yolk-shell silica spheres consisting of a core and an outer shell were prepared by a one-step method using a new class of eco-friendly templates, trisiloxane-tailed surface active ionic liquids. The effects of pH, calcination, and template concentration were investigated in detail. Our results showed that yolk-shell silica spheres could be obtained only in alkaline conditions when using trisiloxane-tailed ionic liquids as templates. The particle diameter, core diameter, dimension of void space, and shell thickness, which we measured by transmission electron microscopy and nitrogen adsorption-desorption techniques, could be tuned by precisely varying the template concentration. The organosilicon component of the ionic liquid template contributes to the reaction during the formation of yolk-shell nanostructures, which leads to a firm silica sphere skeleton resulting in essentially identical morphology and void structure before and after calcination. This investigation provides a convenient approach to fabricate yolk-shell silica spheres, which may expand the application of organosilicon ionic liquids in the field of nanomaterials and could be expected to generate tailor-made yolk-shell silica with functionality in both the core and shell.