Described herein are methods of synthesizing metal nanoparticles and the metal nanoparticles synthesized therefrom. Further described in the present disclosure are methods of modifying the surfaces of metal nanoparticles and the metal nanoparticles modified thereby. Also described herein are uses of such metal nanoparticles.

The present invention provides a preparation method for gold nanoparticles based on functionalized ionic liquid. The method comprises synthesizing a functionalized ionic liquid, 3-(12-bromo-dodecyl)-1-(3-pyrrole propyl)-imidazole bromide, as a stabilizer for synthesizing gold nanoparticles, adjusting the concentration of the ionic liquid and the dosage of the reducing agent, thereby successfully preparing the icosahedral gold nanoparticles, and characterizing the morphology thereof by TEM, XRD and SEM. In the present invention, the method employed for preparing the stabilizer is simple, non-toxic, harmless and pollution-free, moreover the preparation of gold nanoparticles by aqueous phase has the advantages of mild conditions, short reaction time, simple operation, green and pollution-free, and belongs to the environment-friendly preparation.

Provided are processes for preparing a thermodynamically stable PtBi.sub.2 alloy nanoparticle. In certain aspects, the process comprises preparing an aqueous mixture, with the aqueous mixture comprising: an inorganic compound comprising SnCl.sub.2; an inorganic compound comprising Bi; and HCl. The process further comprises adding PtCl.sub.4 to the mixture. The process results in the spontaneous reduction of Bi and Pt. Excess SnCl.sub.2 is adsorbed as a ligand at the surface of the PtB.sub.2 alloy nanoparticle, which serves to stabilize the nanoparticle. Another aspect provides a thermodynamically stable PtBi.sub.2 nanoparticle. The nanoparticle comprises a core comprising a PtBi.sub.2 alloy. The nanoparticle further comprises a shell at least partially encapsulating the core, with the shell comprising stannous chloride. The thermodynamically stable PtB.sub.2 nanoparticle has a negative charge.

The present specification relates to a method for preparing a metal nanoparticle.

The invention relates to the rare metal smelting field, and particularly, the present invention relates to a tantalum powder for preparing capacitors and a process for preparing the tantalum powder, and to a sintered anode prepared from the tantalum powder. As to the tantalum powder as provided by the invention, its primary tantalum powder has a BET of from 3.0 to 4.5 m.sup.2/g. After the secondary agglomeration, the tantalum powder has a large particle size. The tantalum powder has an average Fisher sub-sieve size (FSSS) of 1.2 to 3.0 μm wherein as measured with a standard sieve mesh, more than 75% of tantalum powder has a +325-mesh, and a particle size distribution D50 of more than 60 μm, that is, the secondary particle size is high. A resultant capacitor anode prepared by sintering the tantalum powder of the invention at 1200° C. for 20 minutes and then being energized at the voltage of 20 V has the specific capacitance of from 140,000 to 180,000 μFV/g and the residual current of less than 1.0 nA/μFV. Meantime, the invention provides an economical process for making the tantalum powder.

Processes for preparing stabilized metal-containing nanoparticles comprising silver and/or a silver alloy composite by reacting a silver compound with a reducing agent comprising a hydrazine compound at a temperature between about 20° C. and about 60° C. The reaction being carried out by incrementally adding the silver compound or a mixture of the silver compound and a stabilizer to a solution comprising the reducing agent, a stabilizer, and a solvent. Conductive ink compositions containing stabilized metal-containing nanoparticles prepared by such processes.

The invention relates to nano-particles comprising metallic ferromagnetic nanocrystals combined with either amorphous or graphitic carbon in which or on which chemical groups are present that can dissociate in aqueous solutions.

According to the invention there is provided nano-particles comprising metal particles of at least one ferromagnetic metal, which metal particles are at least in part encapsulated by graphitic carbon.

The nano-particles of the invention are prepared by impregnating carbon containing bodies with an aqueous solution of at least one ferromagnetic metal precursor, drying the impregnated bodies, followed by heating the impregnated bodies in an inert and substantially oxygen-free atmosphere, thereby reducing the metal compounds to the corresponding metal or metal alloy.

A silver powder, wherein the silver powder satisfies D.sub.50-IPA>D.sub.50-W, where in measurement of a volume-based particle size distribution of the silver powder by a laser diffraction particle size distribution analysis, D.sub.50-IPA (μm) is a cumulative 50% point of particle diameter of the silver powder when isopropyl alcohol (IPA) is used as a measurement solvent for dispersing the silver powder, and D.sub.50-W (μm) is a cumulative 50% point of particle diameter of the silver powder when water is used as a measurement solvent for dispersing the silver powder, and wherein a phosphorus content in the silver powder is 0.01% by mass or more but 0.3% by mass or less.

A method for producing metal nanowire of small diameter and long length. In the method for producing a metal nanowire, a first solution containing an ionic derivative and a polyol as a solvent are kept at 80-200° C., and a second solution containing a metal salt and a polyol as a solvent is supplied into the first solution so that the ratio between the number of moles of metal atoms in the metal salt supplied in one minute and the total number of moles of halogen atoms in the ionic derivative in the first solution (the number of moles of metal atoms in the metal salt supplied in one minute/the total number of moles of halogen atoms in the ionic derivative) is less than 10. It is preferable that the ionic derivative is a quaternary ammonium halide and the metal salt is silver nitrate.

Disclosed is a method for preparing vanadium or vanadium alloy powder from a vanadium-containing raw material through a shortened process, including: calcinating a mixture of a vanadium-containing raw material and an alkali compound for oxidation to form a water-soluble vanadate; purifying the vanadate followed by vanadium precipitation to produce an intermediate CaV.sub.2O.sub.6 with high purity; dissolving CaV.sub.2O.sub.6 in a molten-salt medium together with other raw materials to form a uniform reaction system; and introducing a reducing agent to the system followed by separation, washing and drying to produce vanadium or vanadium alloy powder having a particle size of 50-800 nm and a purity of 99.0 wt % or more. The method can continuously process vanadium-containing raw materials to prepare vanadium or vanadium alloy powder.