Method of preparing catalyst for manufacturing carbon nanotubes

Abstract

A novel method of forming catalyst particles, on which carbon nanotubes grow based, on a substrate with increased uniformity, and a method of synthesizing carbon nanotubes having improved uniformity are provided. A catalytic metal precursor solution is applied to a substrate. The applied catalytic metal precursor solution is freeze-dried, and then reduced to catalytic metal. The method of forming catalyst particles can minimize agglomeration and/or recrystallization of catalyst particles when forming the catalyst particles by freeze-drying the catalyst metal precursor solution. The catalyst particles formed by the method has a very uniform particle size and are very uniformly distributed on the substrate.

1 . A method of preparing catalyst particles for carbon nanotube manufacture, the method comprising: 
 applying a catalytic metal precursor solution to a substrate, the catalytic metal precursor solution comprising a catalytic metal precursor and a solvent;    freeze-drying the catalytic metal precursor solution applied to the substrate; and    reducing the freeze-dried catalytic metal precursor to catalytic metal.    
     
     
         2 . The method of  claim 1 , wherein the catalytic metal precursor is an organo-metallic compound.  
     
     
         3 . The method of  claim 2 , wherein the catalytic metal precursor is an organo-metallic compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Y, Mo, Cu, Pt, V, and Ti.  
     
     
         4 . The method of  claim 1 , wherein the solvent of the catalytic metal precursor solution is ethanol, ethylene glycol, polyethylene glycol, polyvinyl alcohol, or a mixture thereof.  
     
     
         5 . The method of  claim 1 , wherein the concentration of the catalytic metal precursor in the catalytic metal precursor solution is 10 mM to 200 mM.  
     
     
         6 . The method of  claim 1 , wherein the step of freeze-drying the catalytic metal precursor solution comprises cooling the catalytic metal precursor solution applied to the substrate below the freezing point of the catalytic metal precursor solution and evaporating the solvent in the catalytic metal precursor solution under a reduced pressure.  
     
     
         7 . The method of  claim 6 , wherein the step of cooling the catalytic metal precursor solution comprises using a freezer or liquid nitrogen.  
     
     
         8 . Catalyst particles prepared by the method of  claim 1 .  
     
     
         9 . A method of manufacturing carbon nanotubes, comprising utilizing the catalyst particles of  claim 8 .  
     
     
         10 . A method of manufacturing carbon nanotubes, the method comprising: 
 forming catalyst particles on a substrate by applying a catalytic metal precursor solution comprising a catalytic metal precursor and a solvent to the substrate, freeze-drying the catalytic metal precursor solution applied to the substrate, and reducing the freeze-dried catalytic metal precursor to a catalytic metal; and    growing carbon nanotubes on the catalyst particles by supplying a carbon source to the catalyst particles.    
     
     
         11 . The method of  claim 10 , wherein the catalytic metal precursor is an organo-metallic compound, and the solvent is ethanol, ethylene glycol, polyethylene glycol, polyvinyl alcohol, or a mixture thereof.  
     
     
         12 . The method of  claim 10 , wherein the catalytic metal precursor is an organo-metallic compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Y, Mo, Cu, Pt, V, and Ti.  
     
     
         13 . The method of  claim 10 , wherein the concentration of the catalytic metal precursor in the catalytic metal precursor solution is 10 mM to 200 mM.  
     
     
         14 . The method of  claim 10 , wherein the step of freeze-drying the catalytic metal precursor solution comprises cooling the catalytic metal precursor solution applied to the substrate below the freezing point of the catalytic metal precursor solution and evaporating the solvent in the catalytic metal precursor solution under a reduced pressure.  
     
     
         15 . The method of  claim 10 , wherein the step of cooling the catalytic metal precursor solution comprises using a freezer or liquid nitrogen.  
     
     
         16 . The method of  10 , wherein the step of growing the carbon nanotubes comprises placing the substrate on which the catalyst particles are formed in a reaction chamber, supplying carbon precursor gas into the reaction chamber, and decomposing the carbon precursor gas in the reaction chamber to supply carbon to the catalyst particles.  
     
     
         17 . The method of  16 , wherein the internal temperature of the reaction chamber is in the range of about 450 to 1100° C.  
     
     
         18 . The method of  claim 10 , wherein the reduction of the freeze-dried catalytic metal precursor to a catalytic metal comprises heating the freeze-dried catalytic metal precursor in an oxidation atmosphere to oxidize the catalytic metal precursor, and reducing the oxidized catalytic metal precursor to the catalyst metal by heat-treatment or plasma-treatment.  
     
     
         19 . A method of manufacturing carbon nanotubes, the method comprising: 
 applying a catalytic metal precursor solution to the substrate, the catalytic metal precursor solution comprising a catalytic metal precursor dissolved in a solvent;    cooling the catalytic metal precursor solution applied to the substrate below the freezing point of the catalytic metal precursor solution;    evaporating the solvent in the catalytic metal precursor solution to form catalytic metal precursor particles;    converting the catalytic metal precursor particles to a catalyst particles; and    growing carbon nanotubes on the catalyst particles.    
     
     
         20 . The method of  claim 19 , wherein the step of converting the catalytic metal precursor particles to the catalyst particles comprises heating the catalytic metal precursor particles in an oxidation atmosphere to oxidize the catalytic metal precursor particles, and reducing the oxidized catalytic metal precursor particles to the catalyst particles by heat-treatment or plasma-treatment.