Nanoporous Metals (NPMs) are nanostructured pure metals with pores ranging from approximately 1-100 nm in diameter. They have been sought-after for their unique combinations of metallic characteristics and nanostructured size-effect properties, ranging from catalysis, plasmonics, battery electrodes to actuators. Many synthesis routes for nanoporous metals have been developed in the past 30 years, the oldest and most popular being the dealloying method. This method involves chemically or electrochemically removing the less-noble element from an alloy, leaving behind a nanoporous metal. Other techniques include combustion synthesis, block-copolymer templating, or directed assembly of metal nanoparticles.

Here, we demonstrate a scalable, room temperature synthesis method capable of producing a variety of nanoporous metal structures. Nanoporous Fe, Co, Au, Cu, Ag and Ni were formed by reacting metal-halide salts with organolithium reducing agents to form a metal/lithium salt nanocomposite. During this conversion reaction, the metal phase coalesces into an interconnected network of fine metal filaments surrounded by a lithium salt matrix. When the lithium salt is removed via dissolution in a polar organic solvent, the metal filament network remains and is an effective nanoporous pure metal (See Figure 1 for representative images). Nitrogen adsorption analysis and microscopy studies showed that these materials have high specific surface area (up to ~160 m²/g) with pore diameters ranging from 2 nm to 50 nm. This technique can also synthesize hybrid nanoporous structures of two or more metals by performing the conversion reaction on mixed precursors. Metals (e.g. Co and Cu) were found to stabilize each other when converted into a hybrid nanoporous structure, resulting in a mixed nanoporous metal with smaller pore sizes and higher surface areas than each respective element in its pure nanoporous metal form. This synthesis pathway greatly expands our access to new compositions and microstructures of nanoporous metals.