Ultralow-Density Nanostructured Metal Foams:  Combustion Synthesis, Morphology, and Composition

Abstract

The synthesis of low-density, nanoporous materials has been an active area of study in chemistry and materials science dating back to the initial synthesis of aerogels. These materials, however, are most often limited to metal oxides, e.g., silica and alumina, and organic aerogels, e.g., resorcinol/formaldehyde, or carbon aerogels, produced from the pyrolysis of organic aerogels. The ability to form monolithic metallic nanocellular porous materials is difficult and sometimes elusive using conventional methodology. Here we report a relatively simple method to access unprecedented ultralow-density, nanostructured, monolithic, transition-metal foams, utilizing self-propagating combustion synthesis of novel transition-metal complexes containing high nitrogen energetic ligands. During the investigation of the decomposition behavior of the high-nitrogen transition metal complexes, it was discovered that nanostructured metal monolithic foams were formed in a post flame-front dynamic assembly having remarkably low densities down to 0.011 g cm(-3) and extremely high surface areas as high as 270 m(2) g(-1). We have produced monolithic nanoporous metal foams via this method of iron, cobalt, copper, and silver metals. We expect to be able to apply this to many other metals and to be able to tailor the resulting structure significantly.

Synthesis and Characterization of Cyclotriphosphazenes Containing Silicon as Single Solid-State Precursors for the Formation of Silicon/Phosphorus Nanostructured Materials

“…In fact, the exothermal peaks at 250°C and 300°C can be assigned to the carbonization of the organic matter. Similar exothermic peaks have been observed during the oxidation of organometallic complexes [36][37][38] .…”

Global scattering functions: a tool for grazing incidence small angle X-ray scattering (GISAXS) data analysis of low correlated lateral structures

“…Thus it can be applied to model the system's structural features starting from the smallest structural level, such as a nanoparticle towards clusters of particles up to the macro-scale. It was applied successfully in transmission scattering geometry to several particle systems [30][31][32]. In addition, it was also applied to scattering from soft matter systems [29,33,34].…”

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

“…There are several techniques available for the preparation of metal nanofoams: dealloying [1][2][3] , sol-gel approaches 4,5 , nanosmelting 6,7 , and combustion synthesis 8 . In the dealloying process, the starting material is usually a binary alloy, for example, an alloy of silver and gold.…”

“…The less noble metal, silver in this case, can be removed either chemically or electrochemically resulting in a disordered porous gold foam with nanosized ligaments. In combustion synthesis, metal is mixed with an energetic precursor that releases energy during its decomposition and drives the formation of metal nanofoam 8 . Studies on the mechanical behavior of metal foams indicate that in disordered architectures stresses cannot be transmitted effectively from the ligament nanoscale to the overall macroscale 9-11. Thus well-ordered metal nanofoams are expected to have superior mechanical properties in comparison to the disordered ones.…”