Method for synthesizing carbon nanotubes

Abstract

The present application is directed to a method for synthesizing carbon nanotubes using magnetic fluid by thermal chemical vapor deposition. The method includes the steps of producing a catalytic metal using the magnetic fluid, coating the produced catalytic metal on a substrate, and thereby synthesizing carbon nanotubes.

1 . A method for synthesizing carbon nanotubes using magnetic fluid by thermal chemical vapor deposition, which comprises the steps of: 
 (S1) producing a catalytic metal using the magnetic fluid;    (S2) coating the produced catalytic metal on a substrate; and    (S3) synthesizing the carbon nanotubes.    
     
     
         2 . The method of  claim 1 , wherein the step (S1) additionally comprises adding a binder to the catalytic metal.  
     
     
         3 . The method of  claim 1 , wherein the magnetic fluid is produced from iron chloride.  
     
     
         4 . The method of  claim 1 , wherein the step (S1) comprises the steps of: 
 (S1-1) producing an aqueous iron chloride solution with ferrous chloride, ferric chloride and distilled water;    (S1-2) heating and stirring the aqueous iron chloride solution;    (S1-3) adding ammonium hydroxide to the aqueous iron chloride solution to produce magnetite (Fe 3 O 4 ) particles;    (S1-4) adding a surfactant to the aqueous iron chloride solution;    (S1-5) adding water and acetone to the aqueous iron chloride solution to separate the magnetite particles from liquid; and    (S1-6) producing a solution of catalytic metal with the magnetite particles, distilled water and a binder.    
     
     
         5 . The method of  claim 4 , wherein the steps (S1-1) and (S1-3) further comprise adjusting the amount of iron chloride and ammonium hydroxide to obtain the magnetite (Fe 3 O 4 ) particles of a desired size.  
     
     
         6 . The method of  claim 5 , wherein the magnetite (Fe 3 O 4 ) particles have a diameter of 10-100 nm.  
     
     
         7 . The method of  claim 4 , wherein the surfactant used in the step (S1-4) is a fatty acid.  
     
     
         8 . The method of  claim 7 , wherein the fatty acid is CH 3 (CH 2 ) 8 CO 2 H.  
     
     
         9 . The method of  claim 7 , wherein a portion of the fatty acid is added several times with interval.  
     
     
         10 . The method of  claim 1 , wherein in the step (S2), the catalytic metal is coated on the substrate by injection.  
     
     
         11 . The method of  claim 1 , wherein in the step (S2), the catalytic metal is coated on the substrate by dipping the substrate in a catalytic metal solution.  
     
     
         12 . The method of  claim 10 , wherein the coating further comprises spin-coating the catalytic metal with a spin coater.  
     
     
         13 . The method of  claim 11 , wherein the coating additionally comprises spin-coating the catalytic metal with a spin coater.  
     
     
         14 . The method of  claim 12 , wherein the spin-coating is performed at a rotational speed of about 100-5,000 rpm.  
     
     
         15 . The method of  claim 2 , wherein the binder is a ceramic binder.  
     
     
         16 . The method of  claim 1 , wherein the step (S3) comprises step (S3-1) of charging the substrate coated with the catalytic metal into a heating device, into which a source gas is then introduced to synthesize the carbon nanotubes on the substrate.  
     
     
         17 . The method of  claim 16 , wherein the source gas comprises acetylene, ammonia and hydrogen.  
     
     
         18 . The method of  claim 16 , wherein the carbon nanotubes are synthesized at an atmospheric temperature of about 800-900° C., after the substrate coated with the catalytic metal is charged into the heating device.  
     
     
         19 . The method of  claim 1 , wherein the steps (S2) and (S3) further comprise coating the substrate in a batch process, and continuously charging the substrate into the heating device.  
     
     
         20 . The method of  claim 19 , wherein prior to charging the substrate into the heating device, the atmospheric temperature in the device is a temperature for synthesizing the carbon nanotubes.