Nanofoam

Nanofoams are a class of nanostructured, porous materials (foams) containing a significant population of pores with diameters less than 100 nm. Aerogels are one example of nanofoam.
Metal.
In 2006, researchers produced metal nanofoams by igniting pellets of energetic metal bis(tetrazolato)amine complexes. Nanofoams of iron, cobalt, nickel, copper, silver, and palladium have been prepared through this technique. These materials exhibit densities as low as 11 mg/cm3, and surface areas as high as 258 m2/g. These foams are effective catalysts and electrocatalyst supports. Also, metal nanofoams can be made by electrodeposition of metals inside templates with interconnected pores, such as 3D-porous anodic aluminum oxide (AAO). Such method gives nanofoams with an organized structure and allows to control the surface area and porosity of the fabricated material.
Carbon.
Carbon nanofoam is an allotrope of carbon discovered in 1997. It consists of a cluster-assembly of carbon atoms strung together in a loose three-dimensional web. The material has a density of 2–10 mg/cm3 (0.0012 lb/ft3).
Glass.
In 2014, researchers also fabricated glass nanofoam via femtosecond laser ablation. Their work consisted of raster scanning femtosecond laser pulses over the surface of glass to produce glass nanofoam with ~70 nm diameter wires.