Caged nanoparticle electrocatalyst with high stability and gas transport property

Patent metadata

Field	Value
Publication number	US-11121379-B2
Application number	US-201614991167-A
Country	US
Kind code	B2
Filing date	Jan 8, 2016
Priority date	Jan 15, 2015
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

A method for forming a caged electrocatalyst particles for fuel cell applications include a step of forming modified particles having a porous SiO2 shell on a surface of platinum-containing particles. The modified particles are subjected to acid treatment or electrochemical oxidation to remove a portion of the platinum-containing particle thereby creating caged electrocatalyst particles having a gap between the platinum-containing particles and their SiO2 shell.

First claim

What is claimed is:

1. A method for forming caged electrocatalyst particles for a fuel cell catalyst layer, the method comprising:
a) reacting platinum group metal-containing particles, which are supported on carbon particles, with an absorption solution, the absorption solution including a compound having formula 1 and a compound having formula 2:
X 1 —R 2 -M-(OR 1 ) n   1

X 2 —R 3 —Y  2

wherein:
X 1 and X 2 are each independently SH or NH 2 ;
R 1 are each independently C 1-6 alkyl;
M is a metal that can form a metal oxide;
Y is a moiety that does not react with the compound having formula 1;
n is an integer represent the number of OR 1 groups attached to M;
R 2 , R 3 are each independently is a C 1-6 alkylenyl;
the compounds having formula 1 and formula 2 being adsorbed onto the platinum group metal-containing particles to form an adsorbed layer over the platinum group metal-containing particles;
b) allowing M in the compound having formula 1 to hydrolyze to form modified particles on the carbon particles, each of the modified particles having a porous metal oxide shell on surfaces of the platinum group metal-containing particles; and then
c) subjecting the modified particles to acid treatment or electrochemical oxidation to remove a portion of the platinum group metal-containing particles from the modified particles and thereby form a gap between the platinum group-metal containing particles and each corresponding porous metal oxide shell that surrounds the platinum group metal-containing particles, thus creating caged electrocatalyst particles in which each of the corresponding metal oxide shells is attached to each of the corresponding carbon particles and the platinum group metal-containing particles are disposed within a central cavity defined by each of the corresponding metal oxide shells such that each of the corresponding metal oxide shells and the platinum group metal-containing particles are separated by the gap inside each of the corresponding metal oxide shells and do not contact one another.

2. The method of claim 1 wherein M is Si, Al, Ti, or W.

3. The method of claim 1 wherein when M is Si or Ti, n is 3 and when M is Al, n is 2.

4. The method of claim 1 wherein M is Si.

5. The method of claim 1 wherein Y is CO 2 H, CH 3 , NH 2 , or halo.

6. The method of claim 1 wherein X 1 and X 2 are each SH.

7. The method of claim 1 wherein the platinum group metal-containing particles are each nanoparticles.

8. The method of claim 1 wherein the platinum group metal-containing particles are platinum alloy particles.

9. The method of claim 8 wherein the platinum group metal-containing particles are PtNi 3 particles, PtCo particles, PtCo 3 particles, PtCu 3 particles, PtFe 3 particles, PdNi 3 particles, PdFe 3 particles, or PdRhFe 3 particles.

10. The method of claim 9 wherein in step c) a portion of the Ni is removed from PtNi 3 particles.

11. The method of claim 1 wherein the compound having formula 1 is mercaptopropyltrimethoxysilane (MPTS).

12. The method of claim 1 wherein the compound having formula 2 is mercaptopropionic acid (MPA).

13. The method of claim 1 wherein step b) comprises dispersing the platinum group metal-containing particles in a mixture comprising water and tetraethoxysilane (TEOS).

14. The method of claim 1 wherein in step c) all of the compound having formula 2 is removed from the surface of the platinum group metal-containing particle.

15. The method of claim 1 wherein step c) comprises stirring the modified particles in a sulfuric acid solution.

16. The method of claim 1 comprising, after step c), converting remaining R—SH on the porous metal oxide shell to R—SO 3 H, R—SO 2 NHSO 2 —R, or R—R—NH 2 , wherein R is a C 1-6 alkyl or a C 1-6 alkylenyl.

17. The method of claim 1 comprising dispersing the caged electrocatalyst particles in isopropanol with a hydrophobic ionic liquid to incorporate the ionic liquid into the gap between the platinum group metal-containing particles and each corresponding metal oxide shell that surrounds the platinum group metal-containing particles.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Kongkanand Anusorn

Classifications

• H01M4/9016 Primary

  Oxides, hydroxides or oxygenated metallic salts · CPC title

• H01M4/9058

  of noble metals or noble-metal based alloys · CPC title

• H01M4/921

  Alloys or mixtures with metallic elements · CPC title

• H01M4/92 Primary

  Metals of platinum group (H01M4/94 {, H01M4/9058} take precedence) · CPC title

• Y02T90/40

  Application of hydrogen technology to transportation, e.g. using fuel cells · CPC title