Powder of fine alloy particles having an uneven surface and method of manufacturing the powder
View Patent ↗The invention provides a powder of fine particles of an alloy of platinum-family metal having a surface with a large amount of unevenness that is suitable as a catalyst metal. It is a powder of an alloy containing T and M in a composition ratio represented by the formula [T X M 1−X ], where T is one or two or more of the elements Fe, Co and Ni, M is one or two or more of the elements Pt, Pd and Ru, X represents a numerical value in the range 0.1-0.9, and wherein: its average grain size as measured under TEM observation (D TEM ) is 50 nm or less, and under TEM observation, a plurality of protruding points is observed on the surface of the particles and indentations are observed between the protruding points, making it a fine powder of alloy particles with an uneven surface. This powder of fine alloy particles has a crystal structure with a face-centered cubic (fcc) structure, and its single crystallinity (D TEM )/(D X ) is 1.50 or greater. In addition, the average grain size of the alloy particles as found by the dynamic light-scattering method is 50 nm or less.
1. A method of producing a powder of fine alloy particles having an uneven surface which is a method for producing a powder of an alloy containing T and M in a composition ratio represented by the formula [T X M 1−x ], where
T is one or two or more of the elements Fe, Co and Ni,
M is one or two or more of the elements Pt, Pd and Ru,
X represents a numerical value in the range 0.1-0.9,
the method comprising the steps of:
dissolving metal salts containing the T component and the M component in a solution of polyhydric alcohol and/or a derivative thereof with a boiling point of 100° C. or greater such that no solids remain, and
heating the solution in an inert gas atmosphere at a temperature of 100° C. or greater and 250° C. or less to reduce the metal salts with the polyhydric alcohol and/or derivative thereof, wherein a solution heat up rate to the temperature of 100° C. or greater and 250° C. or less is 0.5 ° C./minute or more and less than 15° C./min,
thereby synthesizing a powder of alloy particles such that under TEM observation, a plurality of protruding points is observed on the surface of the particles and indentations are observed between the protruding points.
2. The method of producing a powder of fine alloy particles having an uneven surface according to claim 1 , wherein the metal salts are reduced with the polyhydric alcohol and/or derivative thereof in the presence of a nucleating agent added to the solution, the nucleating agent selected from the group consisting of at least one metal salt of Au, Ag Ru, Rh, Pd, Os, Ir or Pt, wherein when the metal component in the at least one metal salt is the same as the M component, a different salt is used for the nucleating agent.
3. A method according to claim 1 further comprising supporting the fine alloy particles having the uneven surface on a carrier by dispersing the fine alloy particles in a dispersant such that there is a space of 1 nm or greater between them to form a suspension and coating the carrier with the formed suspension.