Synthesis of Silica-Nanobelt-Based Aerogels with Plasmonic, Magnetic, and Luminescent Functionality

It remains a great challenge to fabricate functional silica aerogel monoliths with tunable properties due to the lack of simple synthetic methods for introducing functional components into one single gel body in a controllable fashion. Here, we report a generic and scalable method for the assembly of presynthesized silica nanobelts into a macroscopic self-supporting aerogel monolith. The method relies on freezing the silica nanobelt aqueous dispersion, followed by freeze-drying, which allows us to tune the density of the aerogel in a predictable way by varying the concentration of nanobelt dispersion, thus optimizing the thermal insulation properties of the aerogel. Through the same method, silica-nanobelt-based composite aerogels are produced simply by introducing water-dispersible gold nanoparticles, Fe3O4 colloidal spheres, or CdSe/CdS/ZnS core/shell quantum dots into the silica nanobelt dispersions. These functional nanomaterials retain their nanoscopic properties, such as plasmonic effects, superparamagnetic behavior, and luminescent properties in the composite aerogels. This cryogelation method significantly simplifies the process of fabricating silica aerogels and enables easy incorporation of other functional nanoparticles into the nonfunctional silica aerogels, providing a platform for tailoring the properties of the aerogels for designated applications.