Synthesis of Alloy Nanoparticles as a Stable Core for Core-Shell Electrocatalysts

Patent metadata

Field	Value
Publication number	US-2015372312-A1
Application number	US-201414309293-A
Country	US
Kind code	A1
Filing date	Jun 19, 2014
Priority date	Jun 19, 2014
Publication date	Dec 24, 2015
Grant date	—

Abstract

A method for making tungsten-alloy nanoparticles that are useful for fuel cell applications includes a step of combining a solvent system and a surfactant to form a first mixture. A tungsten precursor is introduced into the first mixture to form a tungsten precursor suspension. The tungsten precursor suspension is heated to form tungsten nanoparticles. The tungsten nanoparticles are combined with carbon particles to form carbon-nanoparticle composite particles. The carbon-nanoparticle composite particles are combined with a metal salt to form carbon-nanoparticle composite particles with adhered metal salt, the metal salt including a metal other than tungsten. The third solvent system is then removed. A two-stage heat treatment is applied to the carbon-nanoparticle composite particles with adhered metal salt to form carbon supported tungsten-alloy nanoparticles. A method for making carbon supported tungsten alloys by reducing a tungsten salt and a metal salt is also provided.

First claim

What is claimed is:

1 . A method for making tungsten-alloy nanoparticles comprising:
a) combining a first solvent system and a surfactant to form a first mixture; b) introducing a tungsten precursor into the first mixture to form a tungsten precursor suspension; c) heating the tungsten precursor suspension to form tungsten nanoparticles; d) combining the tungsten nanoparticles with carbon particles in an optional second solvent system to form carbon-nanoparticle composite particles; e) contacting the carbon-nanoparticle composite particles with a metal salt in an optional third solvent system to form carbon-nanoparticle composite particles with adhered metal salt or product particles thereof, the metal salt including a metal other than tungsten; f) collecting carbon-nanoparticle composite particles with adhered metal salt or product particles thereof; and g) applying a two stage heat treatment to the carbon-nanoparticle composite particles with adhered metal salt or product particles thereof to form carbon supported tungsten-alloy nanoparticles, the two stage heat treatment including:
heating the carbon-nanoparticle composite particles with adhered metal salt or product particles thereof to a first heat treatment temperature under a first hydrogen-containing environment; and
heating the carbon-nanoparticle composite particles with adhered metal salt or product particles thereof to a second heat treatment temperature under a second hydrogen-containing environment, the second heat treatment temperature being higher than the first heat treatment temperature, the first hydrogen-containing environment including hydrogen in a higher concentration than in the second hydrogen-containing environment.

2 . The method of claim 1 wherein the metal salt include a component selected from the group consisting of nickel salts, iron salts, cobalt salts, copper salts, molybdenum salts, iridium salts, palladium salts, and combinations thereof.

3 . The method of claim 1 wherein the tungsten alloy includes a metal selected from the group consisting of nickel, iron, cobalt, copper, molybdenum, iridium, palladium, and combinations thereof.

4 . The method of claim 1 wherein the tungsten alloy is a tungsten nickel alloy.

5 . The method of claim 1 wherein the tungsten alloy has an average spatial dimension from about 1 to 10 nanometers.

6 . The method of claim 1 wherein the first solvent system includes solvent with a boiling point greater than about 200° C.

7 . The method of claim 1 wherein the carbon particles have an average spatial dimension from about 10 to 100 nanometers.

8 . The method of claim 1 wherein the first solvent system includes dibenzyl ether.

9 . The method of claim 1 wherein the surfactant is selected from the group consisting of cetyltrimethylammonium bromide, oleylamine, oleic acid, and combinations thereof.

10 . The method of claim 1 wherein the tungsten precursor suspension is heated to a temperature from about 200° C. to 300° C. to form the carbon-nanoparticle composite particles.

11 . The method of claim 1 wherein the first solvent system and the second solvent system each independently include a component selected from the group consisting of ethanol, tetrahydrofuran, o-xylene, and combinations thereof.

12 . The method of claim 1 wherein the first heat treatment temperature is from about 350° C. to 500° C. and the second heat treatment temperature is from about 500° C. to 800° C.

13 . The method of claim 1 wherein the first hydrogen-containing environment includes from 10 to 100 weight percent hydrogen.

14 . The method of claim 1 wherein the second hydrogen-containing environment includes less than 15 weight percent hydrogen.

15 . The method of claim 1 further comprising coating the carbon supported tungsten-alloy nanoparticles with a 0.1 to 2 nanometer platinum layer.

16 . A method for making tungsten-nickel nanoparticles comprising:
a) combining a first solvent system and a surfactant to form a first mixture, the first solvent system including a solvent having a boiling point greater than 200° C.; b) introducing a W(CO) 6 into the first mixture to form a tungsten precursor suspension; c) heating the tungsten precursor suspension to form tungsten nanoparticles; d) combining the tungsten nanoparticles with carbon particles in an optional second solvent system to form carbon-nanoparticle composite particles; e) contacting the carbon-nanoparticle composite particles with a nickel salt in an optional third solvent system to form carbon-nanoparticle composite particles with adhered nickel salt or product particles thereof; f) collecting the carbon-nanoparticle composite particles with adhered nickel salt or product particles thereof; and g) applying a two stage heat treatment to the carbon-nanoparticle composite particles with adhered nickel salt or product particles thereof to form carbon supported tungsten-nickel nanoparticles, the two stage heat treatment including:
heating the carbon-nanoparticle composite particles with adhered nickel salt or product particles thereof to a first heat treatment temperature under a first hydrogen-containing environment; and
heating the carbon-nanoparticle composite particles with adhered nickel salt or product particles thereof to a second heat treatment temperature under a second hydrogen-containing environment, the second heat treatment temperature being higher than the first treatment temperature, the first hydrogen-containing environment including hydrogen in a higher concentration than in the second hydrogen-containing environment.

17 . The method of claim 16 wherein the tungsten-nickel has an average spatial dimension from about 1 to 10 nanometers.

18 . The method of claim 16 wherein the first hydrogen-containing environment includes from 10 to 100 weight percent hydrogen.

19 . Carbon supported tungsten-alloy nanoparticles comprising:
carbon particles having an average spatial dimension from about 10 to 100 nanometers; and tungsten alloy nanoparticles supported on the carbon particles, the tungsten alloy nanoparticles having an average spatial dimension from about 1 to 10 nanometers.

20 . The carbon supported tungsten-alloy nanoparticles of claim 19 comprising tungsten and a metal selected from the group consisting of nickel, iron, cobalt, copper, molybdenum, iridium, palladium, and combinations thereof.

21 . A method of making tungsten alloy particles comprising:
combining a tungsten salt, a metal salt of a metal other than tungsten, and a surfactant to form a reaction mixture; adding a reducing agent to the reaction mixture such to initiate a reduction reaction; adding carbon particles to the reaction mixture; collecting modified carbon particles from the reaction mixture; annealing the modified carbon particles under a hydrogen-containing environment to form carbon-tungsten alloy composite particles in which a tungsten alloy is disposed over the carbon particles, the hydrogen-containing environment including less than about 20 weight percent hydrogen gas with the balance being an inert gas.

22 . The method of claim 21 wherein the surfactant is selected from the group consisting of tetrabutylammonium chloride (TBAC), cetyltrimethylammonium bromide (CTAB) oleylamine, oleic acid, and combinations thereof.

23 . The method of claim 21 wherein the reducing agent is lithium triethylborohydride.

24 . The method

Assignees

• Gm Global Tech Operations Inc

Inventors

• Atwan Mohammed
• Kongkanand Anusorn
• Carpenter Michael K

Classifications

• B22F1/16

  Metallic particles coated with a non-metal (coated with lubricating or binding agents or with organic material B22F1/10) · CPC title

• B22F1/054

  Nanosized particles · CPC title

• H01M4/8882

  Heat treatment, e.g. drying, baking · CPC title

• H01M2250/20

  Fuel cells in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M4/9083

  on carbon or graphite · CPC title