A variety of polyhedral nanocages are provided having a hollow interior, ultrathin walls, and well-defined facets of metal atoms. The nanocages can include a variety of precious metals such as Pt, Au, Ru, Rh, or Ir. The metal atoms can take a face-centered cubic structure with {111} facets on the surface. The walls can be thin, sometimes less than 1 nm in thickness or only a few atomic layers in thickness. The nanocages can provide for efficient uses of valuable precious metals, among other things, in catalysis. For example, catalysts are provided exhibiting high mass activities in oxygen reduction reactions. Methods of making and methods of using the nanocages and catalysts are also provided.

A method for producing a catalyst system for gas reactions comprising at least one planar structure of noble metal having gas-permeable openings, comprising the steps of:

(1) providing at least one noble metal powder consisting of at least substantially spherical noble metal particles, and

(2) repeatedly applying the noble metal powder or powders provided in step (1) in layers to a substrate in a build chamber, respectively followed by an at least partial melting of the respective noble metal powder applied as a layer with high-energy radiation, and allowing the melted noble metal powder to solidify within the scope of additive manufacturing.

Methods of forming metal multipod nanostructures. The methods may include providing a mixture that includes a metal acetylacetonate, a reducing agent, and a carboxylic acid. The mixture may be contacted with microwaves to form the metal multipod nanostructures. The methods may offer control over the structure and/or morphology of the metal multipod nanostructures.

Proposed is an iridium alloy catalyst having reversible catalytic activity for an oxygen evolution reaction (OER), a hydrogen evolution reaction (HER), and a hydrogen oxidation reaction (HOR) by including an iridium alloy including iridium (Ir) and nickel (Ni). The iridium alloy catalyst according to the present disclosure is rapidly converted to an iridium alloy catalyst in an oxide form and an iridium alloy catalyst in a metallic form according to applied voltage by controlling its crystallinity. Thus, even in case an oxide layer is formed after the OER, the oxidation layer disappears during the HER and HOR and the properties of an iridium metal catalyst remain, thereby maintaining HER/HOR performance.

Provided herein are methods of preparing three-dimensional photonic crystals having tunable optical properties and control over stopband location and width, the three-dimensional photonic crystals comprising nanoparticles and spacer groups.

Methods of forming metal multipod nanostructures. The methods may include providing a mixture that includes a metal acetylacetonate, a reducing agent, and a carboxylic acid. The mixture may be contacted with microwaves to form the metal multipod nanostructures. The methods may offer control over the structure and/or morphology of the metal multipod nano structures.

A nanocomposite metal material includes a carrier formed of Zr and two-element metal particles supported on the carrier. The two-element metal is formed of Cu and Ni, and a degree of oxidation of the carrier is more than 31% and 100% or less. In a case where the nanocomposite metal material is disposed in a reaction furnace of a thermal reactor, the inside of the reaction furnace is brought into a vacuum state, and the inside of the reaction furnace is heated to a temperature range of 250° C. or higher and 350° C. or lower with a heating mechanism included in the thermal reactor while supplying at least one of hydrogen gas and deuterium gas into the reaction furnace, excessive heat of the nanocomposite metal material is 100 W/kg or more.

The present invention provides a process for making nanoparticle based bulk materials. Also provided is a single component metal nanoparticle based bulk glass material comprising less than about 1% by weight of ligand capped nanocrystals; and wherein the metal is palladium.

The cathode member for electron beam generation of the present disclosure includes: 95% by area or more of a single phase or two phases of a compound composed of iridium and cerium. A total content of one or more subcomponents of metallic iridium and an oxide of one or more elements of iridium and cerium is 5% by area or less of the cathode member.

The invention includes apparatus and methods for instantiating precious metals in a nanoporous carbon powder.