Ionic liquid-impregnated inorganic material coated catalyst particles, membrane electrode assembly for fuel cells, and fuel cell

Abstract

To provide an ionic liquid-impregnated inorganic material-coated catalyst particle, etc., capable of obtaining a high voltage by including excellent oxygen reduction activities and also having excellent durability.SOLUTION: Ionic liquid-impregnated catalyst particles 1 each comprise a conductive carrier 2 and metal particles 3 that are supported by the conductive carrier 2. At least a portion of each metal particle 3 is coated with an inorganic material 4. At least a part of the surface of the metal particle 3, the surface being coated with the inorganic material 4, is in contact with an ionic liquid 5, and at least one of the requirements A and B described below is satisfied. Requirement A: The conductive carrier is formed of carbon, and the peak intensity ratio (G / D ratio) of the G-band to the D-band as determined by Raman spectroscopy is 1.6 or more and 2.2 or less at the laser wavelength of 532 nm. Requirement B: The conductive carrier has a pore volume of a mesopore region of 0.18 cm3 / g or more as determined by a BJH method, and a peak top pore diameter of the pore distribution curve within the range of 2.6 nm or more and 2.8 nm or less as determined by a BJH method.SELECTED DRAWING: Figure 1

Claims

1. The catalyst particles comprise a conductive carrier and metal particles supported on the conductive carrier, wherein a portion of the surface of the metal particles is coated with an inorganic material. At least a portion of the remaining surface of the metal particles coated with the inorganic material is in contact with the ionic liquid, and the ionic liquid-impregnated inorganic material-coated catalyst particles satisfy at least one of the following A and B. Requirement A: The conductive carrier is carbon, and the peak intensity ratio of the G band to the D band (G / D ratio) measured by Raman spectroscopy is 1.6 or more and 2.2 or less at a laser wavelength of 532 nm. Requirement B: The conductive carrier has a mesoporous pore volume of 0.18 cm³ as determined by the BJH method. ３ The concentration is greater than or equal to / g, and the peak top pore diameter of the pore distribution curve obtained by the BJH method is within the range of 2.6 nm to 2.8 nm.

2. The ionic liquid-impregnated inorganic material-coated catalyst particles according to claim 1, wherein the metal particles are platinum particles and have a crystallite size (1,1,1) of 8 nm or less as determined by XRD.

3. The ionic liquid-impregnated inorganic material coated catalyst particles according to claim 1 or 2, wherein the inorganic material is silica.

4. The ionic liquid is an ionic liquid containing an imidazolium salt, wherein the ionic liquid is an ionic liquid-impregnated inorganic material-coated catalyst particle according to claim 1 or 2.

5. The ionic liquid comprises 1-alkyl-3-methylimidazolium bis(trifluoroomethanesulfonyl)imide, wherein the ionic liquid is an ionic liquid-impregnated inorganic material-coated catalyst particle according to claim 1 or 2.

6. The ionic liquid impregnated inorganic material coated catalyst particles according to claim 1 or 2, wherein the ionic liquid contains at least one selected from the group consisting of 1-butyl-3-methylimidazolium bis(trifluoroomethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bis(trifluoroomethanesulfonyl)imide, and 1-ethyl-3-methylimidazolium bis(trifluoroomethanesulfonyl)imide.

7. The ionic liquid-impregnated inorganic material-coated catalyst particle according to claim 1 or 2, wherein the amount of ionic liquid impregnated in the ionic liquid-impregnated inorganic material-coated catalyst particle is 50 vol% or more and 90 vol% or less of the mesopore volume of the catalyst particle.

8. A membrane electrode assembly for a fuel cell, characterized by comprising a catalyst layer containing catalyst particles coated with an ionic liquid-impregnated inorganic material as described in claim 1 or 2.

9. The fuel cell membrane electrode assembly according to claim 8, characterized in that the catalyst layer further comprises a fibrous material.

10. A fuel cell characterized by comprising catalyst particles coated with an ionic liquid-impregnated inorganic material as described in claim 1 or 2.

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