Production method of electrode catalyst, electrode catalyst, composition for forming gas diffusion electrode, gas diffusion electrode, membrane-electrode assembly (MEA), and fuel cell stack

Patent metadata

Field	Value
Publication number	US-9525180-B2
Application number	US-201515023081-A
Country	US
Kind code	B2
Filing date	Mar 27, 2015
Priority date	Mar 28, 2014
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

Provided is an electrode catalyst production method capable of obtaining, through an easy operation, an electrode catalyst whose chlorine (Cl) species content has been reliably and sufficiently reduced, even when using as an electrode catalyst raw material an electrode catalyst precursor containing a high concentration of chlorine.
The method is to produce an electrode catalyst having a core-shell structure including a support, a core part formed on the support and a shell part formed to cover at least a part of a surface of the core part. The method includes a first step (1) of retaining a liquid containing ultrapure water, a reductant such as a hydrogen-containing gas and an electrode catalyst precursor under at least one stage of a predetermined temperature for a predetermined retention time, such electrode catalyst precursor being produced using a material containing chlorine (Cl) species, and exhibiting a chlorine (Cl) species concentration not lower than a predetermined first chlorine (Cl) species concentration when measured by X-ray fluorescence (XRF) spectroscopy.

First claim

The invention claimed is:

1. A production method of an electrode catalyst having a core-shell structure including a support, a core part formed on said support and a shell part formed to cover at least a part of a surface of said core part, comprising:
a first step (1) of retaining a liquid containing ultrapure water, a reductant and an electrode catalyst precursor under at least one stage of a temperature predetermined within a range of 10 to 95° C. for a predetermined retention time, said electrode catalyst precursor being produced using a material containing chlorine (Cl) species, and exhibiting a chlorine (Cl) species concentration not lower than a predetermined first chlorine (Cl) species concentration when measured by X-ray fluorescence (XRF) spectroscopy;
a second step (2) of preparing a first liquid with the catalyst precursor contained in said liquid obtained after said first step being dispersed in ultrapure water, by adding ultrapure water to said liquid obtained after said first step;
a third step (3) of preparing a second liquid by filtrating and washing the catalyst precursor contained in said first liquid with ultrapure water, and then repeatedly performing washing until an electric conductivity ρ of a filtrate obtained after washing has become not higher than a first predetermined value when measured by a JIS-standard testing method (JIS K0552), such that dispersed in ultrapure water is the catalyst precursor contained in said liquid exhibiting an electric conductivity ρ not higher than said first predetermined value; and
a fourth step (4) of drying said second liquid.

2. The production method of the electrode catalyst according to claim 1 , wherein said first chlorine (Cl) species concentration is 6,000 ppm.

3. The production method of the electrode catalyst according to claim 1 , wherein said reductant is at least one kind of compound selected from an organic acid and an organic acid salt.

4. The production method of the electrode catalyst according to claim 1 , wherein said reductant is at least one kind of compound selected from the group consisting of formic acid, sodium formate, oxalic acid and sodium oxalate.

5. The production method of the electrode catalyst according to claim 1 , wherein said reductant is at least one kind of compound selected from an inorganic acid and an inorganic acid salt.

6. The production method of the electrode catalyst according to claim 1 , wherein said reductant is at least one kind of compound selected from the group consisting of carbonic acid, sodium carbonate, thiosulfuric acid, sodium thiosulfate and hydrogen sulfide.

7. The production method of the electrode catalyst according to claim 1 , further comprising a fifth step (5) of drying the dispersion liquid obtained after said first step.

8. The production method of the electrode catalyst according to claim 7 , wherein said electrode catalyst precursor used in said first step is subjected to a pretreatment process comprising:
a step (P1) of preparing a P1 liquid with an electrode catalyst precursor being dispersed in ultrapure water by adding said electrode catalyst precursor (PI) to the ultrapure water, said electrode catalyst precursor being produced using a material containing chlorine (Cl) species, and exhibiting a chlorine (Cl) species concentration not lower than a predetermined second chlorine (Cl) species concentration when measured by X-ray fluorescence (XRF) spectroscopy;
a step (P2) of preparing a P2 liquid by dispersing an electrode catalyst precursor in ultrapure water, said electrode catalyst precursor being obtained by washing said electrode catalyst precursor contained in said P1 liquid with ultrapure water, and then repeatedly performing washing until an electric conductivity ρ of a filtrate obtained after washing has become not higher than a predetermined value of the step P1 when measured by the JIS-standard testing method (JIS K0552); and
a step (P3) of drying said P2 liquid.

9. The production method of the electrode catalyst according to claim 1 , wherein said first predetermined value is a value selected from a range of not higher than 100 μS/cm.

10. The production method of the electrode catalyst according to claim 1 , wherein said electrode catalyst precursor used in said first step is subjected to a pretreatment process comprising:
a step (P1) of preparing a P1 liquid with an electrode catalyst precursor being dispersed in ultrapure water by adding said electrode catalyst precursor (PI) to the ultrapure water, said electrode catalyst precursor being produced using a material containing chlorine (Cl) species, and exhibiting a chlorine (Cl) species concentration not lower than a predetermined second chlorine (Cl) species concentration when measured by X-ray fluorescence (XRF) spectroscopy;
a step (P2) of preparing a P2 liquid by dispersing an electrode catalyst precursor in ultrapure water, said electrode catalyst precursor being obtained by washing said electrode catalyst precursor contained in said P1 liquid with ultrapure water, and then repeatedly performing washing until an electric conductivity ρ of a filtrate obtained after washing has become not higher than a predetermined value of the step P1 when measured by the JIS-standard testing method (JIS K0552); and
a step (P3) of drying said P2 liquid.

11. The production method of the electrode catalyst according to claim 10 , wherein said second chlorine (Cl) species concentration is 6,000 ppm.

12. The production method of the electrode catalyst according to claim 10 , wherein said predetermined value of the step P1 is a value selected from the range of not higher than 100 μS/cm.

13. The production method of the electrode catalyst according to claim 1 , wherein said shell part contains at least one metal selected from platinum (Pt) and a platinum (Pt) alloy, and said core part contains at least one metal selected from the group consisting of palladium (Pd), a palladium (Pd) alloy, a platinum (Pt) alloy, gold (Au), nickel (Ni) and a nickel (Ni) alloy.

14. The production method of the electrode catalyst according to claim 13 , wherein a platinum (Pt) chloride is used as a raw material of a metal constituting said shell part.

15. The production method of the electrode catalyst according to claim 1 , wherein said shell part has:
a first shell part formed to cover at least a part of the surface of said core part; and
a second shell part formed to cover at least a part of a surface of said first shell part.

16. The production method of the electrode catalyst according to claim 15 , wherein a platinum (Pt) chloride is used as a raw material of a metal constituting said second shell part.

17. A production method of an electrode catalyst having a core-shell structure including a support, a core part formed on said support and a shell part formed to cover at least a part of a surface of said core part, comprising:
a first step′ (1′) of retaining a liquid containing ultrapure water, a hydrogen-containing gas and an electrode catalyst precursor under at least one stage of a temperature predetermined within a range of 10 to 60° C. for a predetermined retention time, said electrode catalyst precursor being produced using a material containing chlorine (Cl) species, and exhibiting a chlorine (Cl) species concentration not lower than a predetermined first chlorine (Cl) species concentration when measured by X-ray fluorescence (XRF) spectroscopy.

18. The production method of the electrode catalyst according to claim 17 , further comprising:
a second step (2) of preparing a first liquid with

Assignees

• N E Chemcat Corp
• N E Chemcat Corp

Inventors

• Mizusaki Tomoteru
• Nagamori Kiyotaka
• Nakamura Yoko
• Tsubaki Takuya

Classifications

• H01M8/1002

  Electricity · mapped topic

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title

• H01M4/88

  Processes of manufacture · CPC title

• Y02P70/56

  Cross-Sectional Technologies · mapped topic

• B01J23/44

  Palladium · CPC title