The cryogelation method represents a simple and sophisticated way for producing highly porous aerogel materials of nanoparticles with extremely large specific surface areas. Therefore, an aqueous dispersion of nanoparticles, which are serving as building blocks, is frozen rapidly by the use of liquid nitrogen. A sudden crystallization of the solvent leads to a formation of many small ice crystals. In this process, the previously dispersed particles are excluded from the ice, so that a network of crystal boundaries filled with nanoparticles is formed. In a subsequent step, the solvent is sublimed and removed by lyophilization, to finally obtain a self-supported monolith. Providing a sufficiently high nanoparticle concentration, the shape of the resulting aerogel resembles the frozen colloid.^[1] This fact offers the opportunity to prepare thin films on substrates by means of doctor blading or, on the other hand, to use molds for the fabrication of other macroscopic shapes.^[2] Besides, a time-consuming hydrogelation step, which would be necessary for a conventional chemical gelation, is avoided. In the end, this procedure is applicable for a variety of nanoparticle systems, due to the fact that there is no chemical selectivity.^[3] Here, we will present the chemical and physical properties of these superstructures and discuss their benefits in consideration of applications in the field of electrochemistry.

[1] A. Freytag, M. Colombo, N. C. Bigall, Z. Phys. Chem., 2017, 231(1), 63-75.

[2] T. Kodanek, Axel Freytag et al., Z. Phys. Chem., 2018, aop.

[3] A. Freytag et al., Angew. Chem. Int. Ed., 2016, 55, 1200-1203.