Method for manufacturing manganese oxide nanostructure and oxygen reduction electrode using said manganese oxide nanostructure
It is an object of the present invention to provide an oxygen reduction electrode having excellent oxygen reduction catalysis ability. In a method of manufacturing a manganese oxide nanostructure having excellent oxygen reduction catalysis ability and composed of secondary particles which are aggregations of primary particles of manganese oxide, a target plate made of manganese oxide is irradiated with laser light to desorb the component substance of the target plate, and the desorbed substance is deposited on a substrate facing substantially parallel to the aforementioned target plate.
1. A method for manufacturing a nanostructured manganese oxide which has oxygen reduction catalysis ability and is formed from secondary particles that is an agglomeration of primary particles, wherein the method comprises the steps of;
removing components from a target plate that comprises one or more kinds of manganese oxides by irradiating the target plate with laser light, and
depositing the removed components on a substrate that is opposed to the target plate substantially in parallel to obtain the nanostructured manganese oxide.
2. The method of claim 1 , wherein the oxygen reduction potential of the nanostructured manganese oxide is in the vicinity of −0.1 V in a cyclic voltammogram employing a cyclic voltammetry, the cyclic voltammetry using a three-electrode cell in which the nanostructured manganese oxide is used as the working electrode, platinum is used as the counter electrode, silver/silver chloride is used as the reference electrode, and an aqueous 0.1mol/l potassium hydroxide solution at pH 13 is usedas the electrolyte.
3. The manufacturing method according to claim 1 , wherein the steps are carried out in an atmosphere comprising inert gas.
4. The manufacturing method according to claim 3 , wherein energy is provided to activate the atmosphere.
5. The manufacturing method according to claim 3 , wherein the pressure of the gas is in the range of no less than 13.33 Pa and no more than 1333 Pa.
6. The manufacturing method according to claim 3 , wherein the pressure of the atmosphere is altered.
7. The manufacturing method according to claim 1 , wherein the steps are carried out in an atmosphere comprising a mixed gas of inert gas and reactive gas.
8. The manufacturing method according to claim 7 , wherein the content of the reactive gas is no less than 0.1% and no more than 50% in terms of the mass flow ratio.
9. The manufacturing method according to claim 7 , wherein the reactive gas is an oxidizing gas.
10. The manufacturing method according to claim 9 , wherein the oxidizing gas is a gas containing oxygen gas.
11. The manufacturing method according to claim 7 , wherein energy is provided to activate the atmosphere.
12. The manufacturing method according to claim 7 , wherein the pressure of the gas is in the range of no less than 13.33 Pa and no more than 1333 Pa.
13. The manufacturing method according to claim 7 , wherein the pressure of the atmosphere is altered.
14. The manufacturing method according to claim 1 , wherein the laser light is pulse laser light with a pulse duration of no less than 5 ns and no more than 20 ns.
15. The manufacturing method according to claim 1 , wherein the laser light is from an excimer laser having halogen gas and noble gas as the laser medium.
16. The manufacturing method according to claim 1 , wherein the energy density of the laser light is no less than 0.5 J/cm 2 and no more than 2 J/cm 2 .
17. The manufacturing method according to claim 1 , wherein the target plate absorbs light having the wavelength range of the laser light.
18. The manufacturing method according to claim 1 , wherein the target plate is a sintered body of manganese oxide.
19. The manufacturing method according to claim 1 , further comprising a step of heating the obtained nanostructured manganese oxide.
20. The manufacturing method according to claim 1 , further comprising a step of installing the target plate and the substrate in the reaction system so as to be facing and parallel to each other in advance before the steps.
21. The manufacturing method according to claim 1 , further comprising a step of adjusting at least one of 1) the pressure of the atmosphere and 2) the distance between the target plate and the substrate, in order to control the size of the high-temperature and the high-pressure region that is formed in the vicinity of the target plate by irradiating the target plate with the laser light.