POSTECH: Ghost-Template Synthesis of Amorphous Hollow Silica Nanostructures

One of the core strategies of nanotechnology is nanostructures, which can be described as a container – smaller than a few hundred thousand the size of a hair strand – that can carry or transport materials. They are widely used as a drug-delivery device or catalyst and can carry more materials if they have a hollow interior, which increases their efficiency. The challenge has been synthesizing these nanostructures – they were usually synthesized by making a template and removing it. A Korean research team has recently proposed a new synthesis technique to fabricate a “ghost template” with metal salts that dissolve.

Hollow octahedral nanostructures have wide applicability since materials freely flow through and easily combine with other materials. These structures had to be synthesized into a template and the template had to be removed again.

Taking a hint from metal salts that dissolve and disappear depending on the acidity of the solution, the researchers developed a simple synthetic method of making a template with metal salt and dissolving it. With this new method, hollow nanostructures, as well as unconventional nanostructures like polygonal or spherical structures, can be synthesized by controlling the reaction rate of the silica precursor.

The researchers also confirmed that these hollow nanostructures can assemble into a large octahedral structure through self-assembly. The hollow interior is a porous material in which chemical reactions occur actively and can be applicable in catalysis, gas storage, and others

Professor In Su Lee explained, “The hollow nanostructures synthesized with this new method use the biocompatible silica and have the structural advantage of hollow interior space and large surface area, making it highly applicable as a catalyst or drug delivery device.”