Fuel cell comprising oxygen electrode with surface nanostructure

Abstract

The present invention is aimed to realize, in a fuel cell with an oxygen electrode (a catalytic electrode), both catalytic function and immobilization of the catalyst nanoparticles when the catalyst nanoparticles are very small nanoparticles in the size of 1-3 nm.Oxygen electrode used in the fuel cell according to the present invention is an oxygen electrode comprising a plurality of carbon particles, a carbon thin-film, and surface nanostructure, wherein the carbon particles are bonded to one another with the carbon thin-film 2, the surface nanostructure is formed on the surface of the carbon thin-film, the surface nanostructure comprises catalyst nanoparticles made of platinum (Pt) and carbon nanoparticles, diameter of each of the carbon particles is 30 nm or more and 100 nm or less, diameter of the catalyst nanoparticle is 1.7 nm or more and 3.1 nm or less, and diameter of the carbon nanoparticle is 1.0 nm or more and 11.2 nm or less. According to this combination of these elements, the catalyst nanoparticles are confined within three-dimensional structure to be formed by the carbon nanoparticles and are immobilized without losing space which allows any reactant to be accessed to the surface of the catalyst nanoparticles.

Description

[0001]This is a continuation application under U.S.C. 111(a) of pending prior International application No. PCT / JP2009 / 001319, filed on Mar. 25, 2009, which in turn claims the benefit of Japanese Application No. 2008-104424 filed on Apr. 14, 2008, the disclosures of which Application are incorporated by reference herein.1. TECHNICAL FIELD[0002]The present invention relates to a fuel cell characterized in surface structure of an oxygen electrode thereof.2. BACKGROUND ART[0003]Power generation performance of fuel cell is strongly depended on net surface area of catalyst contained in a catalytic electrode. When the surface area is increased, the current density at electrical generation is increased to improve the output voltage. Downsizing of catalyst in the form of several nanometer particles is an effective method to increase the surface area of the catalyst per unit mass. Thus, nanoparticles of metal or alloy with a diameter of about 5 nm have usually been used as catalyst nanoparti...

AI Technical Summary

Benefits of technology

[0029]According to the fuel cell of the present invention, improved and stable power generation performance will be realized without reducing reactive area in the catalyst.

Problems solved by technology

According to the foregoing conventional methodologies, since the platinum nanoparticles were completely embedded below carbon overlayers at the earlier stage, any reactive element (oxygen, hydrogen) is not capable of being accessed to the surface thereof to lose any catalytic function.

Thus, it is substantially impossible to apply similar immobilizing treatment to the numerous platinum nanoparticles, any desired immobilizing effect would not be realized thereby.

When chemical bonding force based on molecular cross-linked structure was employed to immobilize the catalyst nanoparticles, there are problems both of significantly changing the surface property of the catalyst nanoparticles with chemical bonding and of significantly reducing the surface area with catalytic activity.

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