Thursday, January 28, 2010

Samsung Unveils Carbon Nanotube Electrodes for Improved Liquid and Gaseous Polymer Electrolyte Fuel Cells


Branched carbon nanotubes directly grown over a carbon substrate can be applied as electrodes in alkaline fuel cells, phosphoric acid fuel cells and solid polymer membrane fuel cells (PEMFC and DMFC), according to Samsung scientists. 

FIG. 2 is a scanning electron microscopic (SEM) photograph showing the uniform distribution of metallic carbon particles over a carbon substrate for use in polymer electrolyte fuel cells  




Samsung SDI Co., Ltd. (Suwon-si, KR) reveals the use of carbon nanotubes for use in a fuel cell, a method for fabricating the same, and a polymer electrolyte fuel cell using the carbon nanotubes for its electrode in U.S. Patent Application 20100018851. The internal and external walls of the carbon nanotubes are doped with nano-sized metallic catalyst particles uniformly to a degree of 0.3-5 mg/cm2.

The carbon nanotubes are grown over a carbon substrate using chemical vapor deposition or plasma enhanced chemical vapor deposition. Since the carbon nanotubes have a large specific surface area, and metallic catalyst particles are uniformly distributed over the internal and external walls, the reaction efficiency in an electrode becomes maximal when the carbon nanotubes are used for the electrode of a fuel cell.

The carbon nanotubes fabricated using the method can be applied to form a large electrode. The carbon nanotubes grown over the carbon substrate can be readily applied to an electrode of a fuel cell, providing economical advantages and simplifying the overall electrode manufacturing process. A fuel cell using as the carbon nanotubes for its electrode provides improved performance, says inventors Won-bong Choi,  Jae-uk Chu, Chan-ho Park and Hyuk Chang.

The electrodes can be used in both proton exchange membrane fuel cells and direct methanol fuel cells.

FIG. 3 is a SEM photograph of carbon nanotubes for use in fuel cells.

 


FIG. 4 is a transmission electron microscopic (TEM) photograph of a branched carbon nanotube for use in fuel cells.   


In addition, since the carbon nanotubes are directly grown over a carbon substrate that can be used for an electrode, the carbon substrate with the carbon nanotubes grown thereover can be readily applied as an electrode of a fuel cell at low costs, without the need for complicated electrode manufacturing processes.

Moreover, since mono, binary, ternary or higher metallic elements can be used as a catalyst, the carbon nanotubes grown over a carbon substrate according to the present invention can be used for cathodes as well as anodes. When branched carbon nanotubes are grown over a carbon substrate using CVD or PECVD method, the branched carbon nanotubes grown over the carbon substrate have a larger surface area, so that they can be used for more effective electrodes. A fuel cell using as an electrode a carbon substrate over which the carbon nanotubes are grown provides improved performance, compared to conventional fuel cells.




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