Electrocatalyst for electrochemical cell, method for producing the electrocatalyst, electrochemical cell, single cell of fuel cell, and fuel cell
An electrocatalyst for an electrochemical cell of the present invention includes a metal catalyst containing metal that has a metal oxidation potential of 0.5V or higher to 1.5V or lower, and is directly involved in an electrode reaction. Further, the electrocatalyst includes an aromatic heterocyclic compound having a six-membered cyclic structure containing a heteroatom, wherein the heteroatom has a metal coordination capacity that is not directly involved in the electrode reaction. The aromatic heterocyclic compound is heterogeneously adsorbed and coordinated on a surface of the metal catalyst while interposing the heteroatom therebetween.
1. An electrocatalyst for an electrochemical cell, comprising:
a metal catalyst which contains metal having a metal oxidation potential of 0.5V or higher to 1.5V or lower, the metal being directly involved in an electrode reaction; and
an aromatic heterocyclic compound which has a six-membered ring structure containing a heteroatom, the heteroatom having a metal coordination capacity that is not directly involved in the electrode reaction,
wherein the aromatic heterocyclic compound is heterogeneously adsorbed and coordinated on a surface of the metal catalyst while interposing the heteroatom therebetween, and
wherein the aromatic heterocyclic compound coordinated in a ratio of 0.1 to 1.5 nmol/cm 2 per unit area of the metal exposed to the surface of the metal catalyst.
2. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the metal that has the oxidation potential is metal belonging to fourth to sixth periods of the Periodic Table.
3. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the metal that has the oxidation potential is metal belonging to groups IV to XII of the Periodic Table.
4. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the metal that has the oxidation potential is metal belonging to groups VI to XI of the Period Table.
5. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the metal catalyst is at least one selected from the group consisting of platinum, rhodium and palladium, and/or alloys of these.
6. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the aromatic heterocyclic compound is adsorbed and coordinated on 20 to 70% of the at least one selected from the group consisting of platinum, rhodium and palladium, and/or the alloys of these, which are exposed to the surface of the metal catalyst.
7. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the aromatic heterocyclic compound is adsorbed and coordinated on 30 to 60% of the at least one selected from the group consisting of platinum, rhodium and palladium, and/or the alloys of these, which are exposed to the surface of the metal catalyst.
8. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the heteroatom contained in the aromatic heterocyclic compound is a nitrogen atom.
9. The electrocatalyst for an electrochemical cell according to claim 1 , wherein the aromatic heterocyclic compound is a pyridine derivative.
10. The electrocatalyst for an electrochemical cell according to claim 9 , wherein the pyridine derivative is at least one derivative selected from the group consisting of bipyridines, terpyridines and phenanthrolines.
11. The electrocatalyst for an electrochemical cell according to claim 9 , wherein the pyridine derivative is 2,2′-bipyridine.
12. An electrocatalyst for an electrochemical cell, comprising:
a metal catalyst which contains metal that is directly involved in an electrode reaction; and
an aromatic heterocyclic compound that is adsorbed on the surface of the metal catalyst and which has a six-membered ring structure containing a heteroatom, the heteroatom having a metal coordination capacity that is not directly involved in the electrode reaction,
wherein, in comparison with a metal catalyst with which the aromatic heterocyclic compound does not exist, a rising potential in an oxidation reaction of the metal catalyst itself, which is observed in a current-potential behavior, is shifted to a high potential side, or an oxidation peak of the metal catalyst itself is reduced, and
wherein the aromatic heterocyclic compound is coordinated in a ratio of 0.1 to 1.5 nmol/cm 2 per unit area of the metal exposed to the surface of the metal catalyst.
13. The electrocatalyst for an electrochemical cell according to claim 12 , wherein the aromatic heterocyclic compound is adsorbed and coordinated on 20 to 70% of at least one selected from the group consisting of platinum, rhodium and palladium, and/or alloys of these, which are exposed to a surface of the metal catalyst.
14. A method for producing an electrocatalyst for an electrochemical cell according to claim 1 , the method comprising:
dissolving the aromatic heterocyclic compound in a solvent into a predetermined concentration;
dispersing the metal catalyst, on which the metal having the metal oxidation potential of 0.5V or higher to 1.5V or lower is supported, into a solution in which the aromatic heterocyclic compound is dissolved;
mixing and stirring the solution into which the metal catalyst is dispersed; and
taking out and drying the metal catalyst on which the aromatic heterocyclic compound is adsorbed and coordinated.
15. An electrochemical cell, comprising:
as a cathode electrode, an electrocatalyst for an electrochemical cell according to claim 1 .
16. The electrochemical cell according to claim 15 , wherein the electrocatalyst for an electrochemical cell is used in a state where a voltage of higher than 0V to 1.2V or lower is applied thereto.
17. A single cell of a fuel cell, comprising:
an electrochemical cell according to claim 15 ; and
a solid polymer electrolyte membrane.
18. A fuel cell, comprising:
a single cell of a fuel cell according to claim 17 .