CN-121985995-A - Carbon-supported platinum or platinum alloy catalyst, method for producing same, membrane electrode assembly for solid polymer fuel cell using carbon-supported platinum or platinum alloy catalyst, and solid polymer fuel cell

CN121985995ACN 121985995 ACN121985995 ACN 121985995ACN-121985995-A

Abstract

The object is to provide a carbon-supported platinum or platinum alloy catalyst for a solid polymer fuel cell which has high activity and high durability. The solution is a carbon-supported platinum or platinum alloy catalyst in which platinum particles or platinum alloy particles are supported on mesoporous carbon, wherein the platinum or platinum alloy loading rate in the catalyst is 30% to 70% of the total weight of the catalyst on a weight basis, the total weight of the platinum particles or platinum alloy particles supported outside pores of the mesoporous carbon is 60% to 90% of the total weight of the platinum particles or platinum alloy particles, the average particle diameter D1 of the platinum particles or platinum alloy particles supported inside pores of the mesoporous carbon is the same as or greater than the average particle diameter D2 of the platinum particles or platinum alloy particles supported outside pores of the mesoporous carbon, and the average particle diameters D1 and D2 are respectively 2nm to 8nm independently.

Inventors

ITO TAKAYOSHI
AOKI NAOYA
KAZUNORI KOGA
An Lianer
KOBAYASHI DAIKI
NAKAE RYOSUKE

Assignees

石福金属兴业株式会社

Dates

Publication Date: 20260505
Application Date: 20241001
Priority Date: 20231003

Claims (8)

1. A carbon-supported platinum or platinum alloy catalyst having platinum particles or platinum alloy particles supported on mesoporous carbon, characterized in that: the platinum or platinum alloy loading rate in the catalyst is more than 30% and less than 70% of the total weight of the catalyst based on weight, The total weight of the platinum particles or the platinum alloy particles loaded outside the pores of the mesoporous carbon is 60% -90% relative to the total weight of the platinum particles or the platinum alloy particles, The average particle diameter D1 of the platinum particles or platinum alloy particles supported in the pores of the mesoporous carbon is the same as or larger than the average particle diameter D2 of the platinum particles or platinum alloy particles supported outside the pores of the mesoporous carbon, The average particle diameter D1 and the average particle diameter D2 are each independently 2nm to 8 nm.
2. The carbon-supported platinum or platinum alloy catalyst according to claim 1, wherein: The average particle diameter D1 is 2.5nm or more and 8nm or less, The average particle diameter D2 is 2.3nm or more and 7.3nm or less, D1/D2 is 1.0-2.1.
3. A method for producing a carbon-supported platinum catalyst, comprising an in-pore supporting step of supporting platinum in pores of a mesoporous carbon support and an out-pore supporting step of supporting platinum particles out of the pores of the mesoporous carbon support, Wherein the pore-loading step includes: impregnating a mesoporous carbon support with an aqueous solution of a platinum-containing compound, A step of drying the mesoporous carbon support impregnated with the aqueous solution containing the platinum compound obtained in the step under reduced pressure, and A step of heat-treating the decompressed and dried mesoporous carbon support obtained in the decompressed and dried step in a reducing atmosphere; The pore external loading process includes: A step of suspending the mesoporous carbon support having platinum supported in the pores after the pore-supporting step in an aqueous solution, and And a step of mixing the suspension with an aqueous solution containing a platinum compound and a liquid containing a reducing agent and reducing the platinum compound.
4. The method for producing a carbon-supported platinum catalyst according to claim 3, wherein, The pore internal loading process includes: Adding dinitroso diammine platinum nitrate aqueous solution into the mesoporous carbon carrier and mixing to obtain carbon-carried platinum slurry, A step of drying the slurry obtained at a predetermined temperature under reduced pressure to form a dry solid, A step of performing a heat treatment in a reducing atmosphere to reduce dinitroso diammine platinum, and A step of firing in an inert gas atmosphere (firing temperature T1) to grow platinum particles; The pore external loading process includes: Suspending the mesoporous carbon carrier loaded with platinum in the pores after the pore loading process in a nitric acid aqueous solution, A step of heating and stirring the suspension with an aqueous dinitroso diammine platinum nitrate solution and a liquid containing L-ascorbic acid at 80 to 100 ℃ for 30 minutes to 5 hours to support platinum particles outside the pores of the carbon support, and And a step of filtering out the carbon-supported platinum in which the platinum particles are supported outside the pores of the carbon support through the above step, washing, drying, and firing in an inert gas atmosphere (firing temperature T2) to grow the platinum particles.
5. The method for producing a carbon-supported platinum alloy catalyst according to claim 3 or 4, comprising: A step of adding an aqueous solution containing a compound of a metal to be alloyed with the platinum to the carbon-supported platinum catalyst and mixing the aqueous solution to obtain a slurry, A step of heating and drying the obtained slurry under reduced pressure to form a dry solid, and And an alloying step of firing the dry solid in an inert gas atmosphere to perform alloying treatment after the dry solid is fired in a reducing atmosphere.
6. The method for producing a carbon-supported platinum or platinum alloy catalyst according to claim 3 or 4, wherein the average particle diameter D1 of the platinum particles and the average particle diameter D2 of the platinum particles are controlled by setting the firing temperature T1 and the firing temperature T2 to predetermined temperatures, respectively.
7. A membrane electrode assembly for a polymer electrolyte fuel cell, wherein the electrode comprises the carbon-supported platinum or platinum alloy catalyst according to claim 1.
8. A solid polymer fuel cell comprising the carbon-supported platinum or platinum alloy catalyst according to claim 1.

Description

Carbon-supported platinum or platinum alloy catalyst, method for producing same, membrane electrode assembly for solid polymer fuel cell using carbon-supported platinum or platinum alloy catalyst, and solid polymer fuel cell Technical Field The present invention relates to a highly active and highly durable carbon-supported platinum or platinum alloy catalyst for a solid polymer fuel cell, wherein platinum particles or platinum alloy particles are supported on the inside and outside of pores of a support. Background In recent years, as a countermeasure for energy and environmental problems, decarbonizing and carbon neutralization have been proposed, and the use of hydrogen has been attracting attention as a clean energy source for replacing chemical fuels. A fuel cell that generates electricity by chemically reacting hydrogen with oxygen is expected to be a novel power generation system that contributes to carbon neutralization because it does not emit carbon dioxide as a greenhouse gas. Among them, a Polymer Electrolyte Fuel Cell (PEFC), which is one of fuel cells, uses a polymer electrolyte membrane in an electrolyte layer, and has a low operating temperature of normal temperature to 100 ℃ to achieve miniaturization of the device, and thus has been put into practical use as a power source for electric vehicles and a stationary power source. The polymer electrolyte fuel cell has a stack structure in which a plurality of unit cells are stacked with Membrane Electrode Assemblies (MEA) sandwiched between separators. The MEA has a structure in which two electrode catalyst layers composed of an electrode catalyst and an electrolyte polymer (ionomer) sandwich an electrolyte layer. In the MEA, the following electrochemical reaction is performed to generate electricity. First, hydrogen supplied as fuel is oxidized by an electrode catalyst in a fuel electrode (anode) side electrode catalyst layer to become protons and electrons. Next, the generated protons pass through the electrolyte layer composed of the ion-conductive electrolyte, while the electrons pass through an external circuit, and reach the oxygen electrode (cathode) side electrode catalyst layer, respectively. Protons and electrons reaching the cathode-side electrode catalyst layer react with oxygen supplied to the cathode side to generate water. Electrons generated in the anode-side electrode are used as electric energy when they move to the cathode-side electrode via an external circuit. In the conventional electrode catalyst, a carbon-supported platinum or platinum alloy catalyst is used, in which nanoparticles of platinum (Pt) or a platinum alloy are supported on a carbon black support having high electron conductivity. In the carbon-supported platinum or platinum alloy catalyst, carbon having a high specific surface area is used to highly disperse and support platinum particles or platinum alloy particles without aggregation, so that the electrode reaction area on the surface of the platinum particles or platinum alloy particles can be increased, and sufficient activity can be exhibited with a small platinum or platinum alloy support amount. In view of the popularization of Fuel Cell Vehicles (FCV) for carbon neutralization, development of a cathode catalyst for a solid polymer fuel cell (PEFC) which is efficient and can be operated at high load has been demanded. In reference 1, there is a carbon-supported platinum catalyst, which is supported on solid structural carbon blocked inside particles such as furnace black or acetylene black. Patent document 2 discloses a catalyst for an electrode in which platinum particles are supported in pores of a porous hollow carbon support such as ketjen black. It is mentioned that by supporting platinum particles in the pores, adsorption of the ionomer on the surface of the platinum particles is suppressed, and the reduction of the effective reaction surface area of the platinum particles can be prevented. Prior art literature Patent literature Patent document 1, japanese patent laid-open No. 2007-112660; patent document 2, japanese patent application laid-open No. 2013-109856. Disclosure of Invention Problems to be solved by the invention For example, a carbon-supported platinum catalyst having solid carbon blocked in the interior of particles such as furnace black or acetylene black has excellent material transport characteristics because platinum particles are supported on the surface of the carrier, and the reaction gas is likely to contact with and react with the platinum particles, but the platinum particles are located on the surface of the carrier, and there is a problem that the activity is lowered due to poisoning of an ionomer or the catalyst is deteriorated due to aggregation (sintering) of the platinum particles. On the other hand, carbon-supported platinum catalysts in which platinum particles are supported in pores using porous carbon such as ketjen black as a carrier have also been widely used. Si