METHOD FOR MANUFACTURING PLATINUM CATALYST, AND FUEL CELL USING SAME
|発明の名称 （英語）||METHOD FOR MANUFACTURING PLATINUM CATALYST, AND FUEL CELL USING SAME|
|発明の概要（英語）||The purpose of the present invention is to provide a method for manufacturing a platinum core-shell catalyst that uses palladium (Pd) as a core metal, or a platinum catalyst containing platinum and a metal besides platinum, wherein the platinum catalyst is supported on carbon and has excellent oxygen reduction activity; and a manufacturing method by which it is possible to manufacture the catalyst industrially on a mass scale. This method for manufacturing a platinum catalyst for a fuel cell containing platinum and a metal besides platinum includes (I) a step for bringing about the presence of a chemical species imparting higher potential than the initial oxide formation potential of the platinum of the platinum catalyst, and (II) a step for bringing about the presence of a chemical species imparting lower potential than the initial oxide formation potential of the platinum of the platinum catalyst, the steps being carried out in a dispersion solution of the platinum catalyst dispersed in an acidic solution containing protons.|
Is a solid polymer fuel cell (PEFC), the oxidation reaction of hydrogen to the anode side, the reduction reaction of oxygen on the cathode side by causing, in clean energy device to generate only water, as a catalyst on the cathode side, platinum (Pt) known in advance is used. To use the platinum catalyst is a noble metal, and high catalyst activity and, in addition, a state of the environment around the substance present in the environment around a sensor less susceptible to corrosion due to poisoning the advantage.
On the other hand, platinum is a small amount of resources and the problem that the price is high, its use to improve the efficiency and durability in order to reduce the use amount has been variously examined. As one of the study, the dissimilar metal on the support is coated with a platinum core-shell catalyst has attracted attention. Core-shell catalyst is platinum, the platinum atoms exhibit catalytic activity of the catalyst particles exposed on the outermost layer of platinum atoms only in is devised by paying attention to, coated with platinum atomic layer (shell) (core) is dissimilar metal fine particles, a carrier such as carbon or the like having a configuration in which are supported in high dispersion.
As one of the core metal of a platinum core shell catalyst, known palladium (Pd). Non-patent document 1 and non-patent document 2 is, in the case of using Pd as the core metal, the oxygen reduction reaction in PEFC (Oxygen Reduction Reaction: ORR) disclosed increases the activity. Pd (0. 38898 nm) is the lattice constant of less than Pt(0.39231 nm), provided on the core shell Pt Pd a slight compressive stress is generated. These compressive stresses, the oxygen reduction reaction on the surface of the shell Pt tends to the realization of the situation, it is considered ORR activity are increased.
Platinum shell, a core-shell core a palladium catalyst, as described above which the activity was improved ORR on the other hand, the standard oxidation-reduction potential (0.92 V vs. NHE) Pt(1.19 V vs. NHE) Pd is lower than for, there is a problem in its durability. In non-patent document 3, the carbon-supported Pd/Pt core shell catalyst (hereinafter, may be referred to as Pt/Pd/C catalyst.) Used in the PEFC cathode, a part of the core Pd dissolved by power generation, the solid polymer electrolyte film and a metal is re-precipitated Pd, Pd is the appearance of bands have been reported.
The inventors already, the elution is Pd oxide core problem from the viewpoint of the durability of the catalyst on the one hand, by elution of the oxide of the catalyst Pd Pt/Pd/C change occurs in the particle size and form, an increase in finding ORR activity. Is Patent Document 1, conventional, (Accelerated Durability Test, ADT) potential cycles of the catalyst after the durability test has been carried out as the voltage is removed, due to the enhanced activity of the catalyst Pt/Pd/C result in disclosed. Is Patent Document 1, Pt/Pd/C catalyst, an oxide of Pt and a potential higher than the redox initiation, initiation potential Pt oxide generation of repeatedly by applying an electric potential lower than, the activity of the catalyst Pt/Pd/C disclosed can also be enhanced.
Disclosed in Patent Document 1 specific potential applying method, platinum in the proton of the acidic solution containing dispersed core-shell catalyst, the oxidation-reduction potential of the oxide of a platinum core shell catalyst start potential lower than the metal coexist while, in such a way that the oxygen supply was is stirred. The method is a completely new technique to, obtain a certain effect in the above, a further improvement in ORR activity has been expected.
On the other hand, the catalyst of the platinum alloys of Patent Document 2 is disclosed and a method for manufacturing. Patent Document 2 disclosed methods of fabrication, and the organometallic complex of the platinum metal chloride from the dispersed in an organic solvent, a mixed solution prepared by adding a reducing agent by pressing and heating, the alloy nano-particles of 2 nm or less in diameter to synthesize and platinum, the platinum alloy nano-particles 300 °C or more in a vacuum heating (annealing) at a temperature below 1000 °C and, the diameter of 2 nm or more and a step 100 nm or less. In the invention of Patent Document 2, a platinum alloy nanoparticle followed by heating (annealing) is performed, the particle diameter of 2 nm or more alloy adjusted to not more than 100 nm, to obtain alloy particles having a particular crystalline form of platinum can be considered.
National States: AE AG AL AM AO AT AU AZ BA BB BG BH BN BR BW BY BZ CA CH CL CN CO CR CU CZ DE DK DM DO DZ EC EE EG ES FI GB GD GE GH GM GT HN HR HU ID IL IN IR IS KE KG KN KP KR KZ LA LC LK LR LS LU LY MA MD ME MG MK MN MW MX MY MZ NA NG NI NO NZ OM PA PE PG PH PL PT QA RO RS RU RW SA SC SD SE SG SK SL SM ST SV SY TH TJ TM TN TR TT TZ UA UG US UZ VC VN ZA ZM ZW
ARIPO: BW GH GM KE LR LS MW MZ NA RW SD SL SZ TZ UG ZM ZW
EAPO: AM AZ BY KG KZ RU TJ TM
EPO: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
OAPI: BF BJ CF CG CI CM GA GN GQ GW KM ML MR NE SN ST TD TG
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