ELECTRODE CATALYST, METHOD FOR PRODUCING SAME, AND FUEL CELL
An electrode catalyst includes a mesoporous carbon support having pores, and catalyst metal particles supported in at least some of the pores of the support. The catalyst metal particles are constituted by an alloy of platinum and at least one transition metal selected from Groups 3 to 12 elements of the periodic table. An average degree of alloying of the electrode catalyst calculated by Equation (1) below is 40% or more. A ratio r/R of a mean particle size r of the catalyst metal particles to a modal pore size R of the mesoporous carbon support is from 0.20 to 0.95. Equation (1) is: Degree (%) of alloying=[lattice constant of alloy calculated from XRD−lattice constant of platinum]/[theoretical value of lattice constant of alloy−lattice constant of platinum]×100.
1 . An electrode catalyst comprising:
a mesoporous carbon support having pores; and
catalyst metal particles supported in at least some of the pores of the support,
wherein the catalyst metal particles comprise an alloy comprising: platinum; and at least one transition metal selected from Groups 3 to 12 elements of the periodic table,
an average degree of alloying of the catalyst metal particles calculated by Equation (1) below is 40% or more, and
a ratio r/R of a mean particle size r of the catalyst metal particles to a modal pore size R of the mesoporous carbon support is from 0.20 to 0.95,
Degree
(
%
)
of
alloying
=
[
lattice
constant
of
alloy
calculated
from
XRD
-
lattice
constant
of
platinum
]
/
[
theoretical
value
of
lattice
constant
of
alloy
-
lattice
constant
of
platinum
]
×
100.
(
1
)
2 . The electrode catalyst according to claim 1 , wherein the mean particle size of the catalyst metal particles is 10.0 nm or less.
3 . The electrode catalyst according to claim 1 , wherein the modal pore size R of the mesoporous carbon support is from 3.0 to 30.0 nm.
4 . An electrode catalyst layer for a fuel cell, comprising the electrode catalyst according to claim 1 .
5 . A fuel cell comprising the electrode catalyst layer for a fuel cell according to claim 4 .
6 . A method for producing an electrode catalyst, comprising:
passing a pressurized fluid through a mixture containing a mesoporous carbon support having pores and a catalyst metal source compound to obtain an intermediate in which the catalyst metal source compound is supported in the pores of the mesoporous carbon support; and
heating the intermediate at a temperature of 400 to 930° C. in a hydrogen-containing atmosphere to generate catalyst metal particles from the catalyst metal source compound.
7 . The production method according to claim 6 , wherein a carbon dioxide fluid at a pressure of 7 to 30 MPa is passed through the mixture of the mesoporous carbon support having pores and the catalyst metal source compound.