Method for producing core-shell catalyst

Patent metadata

Field	Value
Publication number	US-9941521-B2
Application number	US-201515313264-A
Country	US
Kind code	B2
Filing date	Apr 3, 2015
Priority date	May 28, 2014
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

The disclosure is to provide a method for producing a core-shell catalyst that is able to increase the power generation performance of a membrane electrode assembly. A dispersion is prepared, in which a palladium-containing particle support, in which palladium-containing particles are supported on an electroconductive support, is dispersed in water; hydrogen gas is bubbled into the dispersion; the palladium-containing particles are acid treated after the bubbling; copper is deposited on the surface of the palladium-containing particles by applying a potential that is nobler than the oxidation reduction potential of copper to the palladium-containing particles in a copper ion-containing electrolyte after the acid treatment; and then a shell is formed by substituting the copper deposited on the surface of the palladium-containing particles with platinum by bringing the copper deposited on the surface of the palladium-containing particles into contact with a platinum ion-containing solution.

First claim

What is claimed is:

1. A method for producing a core-shell catalyst comprising a core containing palladium and a shell containing platinum and covering the core,
wherein the method comprises:
a step of preparing a dispersion in which a palladium-containing particle support, in which palladium-containing particles are supported on an electroconductive support, is dispersed in water;
a bubbling step of bubbling hydrogen gas into the dispersion;
an acid treatment step of acid treating the palladium-containing particles after the bubbling step;
a copper deposition step of depositing copper on the surface of the palladium-containing particles by applying a potential that is nobler than the oxidation reduction potential of copper to the palladium-containing particles in a copper ion-containing electrolyte after the acid treatment step; and
a substitution step of forming the shell by substituting the copper deposited on the surface of the palladium-containing particles after the copper deposition step with platinum by bringing the copper deposited on the surface of the palladium-containing particles into contact with a platinum ion-containing solution.

2. The method for producing the core-shell catalyst according to claim 1 , wherein the method further comprises a boil-washing step of boil-washing the palladium-containing particles with water after the acid treatment step and before the copper deposition step.

3. The method for producing the core-shell catalyst according to claim 1 , wherein the acid is at least one selected from the group consisting of sulfuric acid and nitric acid.

4. The method for producing the core-shell catalyst according to claim 1 , wherein the electroconductive support comprises at least one of a carbonaceous material and a metal material.

Assignees

• Toyota Motor Co Ltd

Inventors

• Kitao Noriyuki
• Sasaki Naoyuki
• Fujisawa Tsugio

Classifications

• C25D3/38

  of copper · CPC title

• C23C18/1671

  Electric field · CPC title

• C23C18/16

  by reduction or substitution, e.g. electroless plating (C23C18/54 takes precedence) · CPC title

• C23C18/1837

  Multistep pretreatment · CPC title

• C23C18/1844

  with use of organic or inorganic compounds other than metals, first · CPC title