Silica-based nanoarchitectures

One of the most typical clay-based nanoarchitectures is the so-called pillared clays (PILCs). They are built by incorporation of diverse species in the interlayer region of layered silicates, such as smectites, which provoke a permanent separation of the structural layers as do pillars in the building constructions. PILCs are mainly prepared in two-step processes in which polyoxocations of diverse type of metal (e.g., Al(III), Cr(III), Fe(III), and Ga(III)) are first intercalated by ion exchange reactions and further transformed into oxide particles by an adequate thermal treatment [8]. In certain cases, for instance, in the preparation of silica. 

Similar silica-montmorillonite nanoarchitectures have also been prepared by sol-gel, as reported by Qian et al., using TEOS and another type of clay (from Zhangjiakou, China), corroborating the usefulness of this methodology in the development of silica-silicate-based porous materials [58]. 

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