Method for opening carbon nanotubes at the ends thereof and implementation

Abstract

The invention relates to an efficient and non-damaging method for opening carbon nanotubes, characterized in that it consists of two oxidation stages, the first in liquid phase in a concentrated acid, the second in gaseous phase.

1 . A method for opening carbon nanotubes comprising a first oxidation stage of said nanotubes in a liquid phase in a concentrated acid and a second oxidation stage of said nanotubes in gaseous phase.  
     
     
         2 . The method of  claim 1 , wherein the carbon nanotubes are multiwall carbon nanotubes.  
     
     
         3 . The method according to  claim 2 , wherein the concentrated acid is nitric acid.  
     
     
         4 . The method according to  claim 3 , wherein said first oxidation comprises contacting said nanotubes and nitric acid in the following proportions: 1 g of carbon nanotubes in 0.5 litres to 2 litres of concentrated nitric acid at 60-75% by weight.  
     
     
         5 . The method according to  claim 2  wherein said first oxidation stage further comprises heating at reflux, under stirring.  
     
     
         6 . The method according to  claim 1 , wherein said second oxidation stage is performed in the presence of carbon dioxide at low temperature.  
     
     
         7 . The method according to  claim 6 , wherein said second oxidation stage is performed in the presence of carbon dioxide at 500 to 600° C., for 1 to 2 hours.  
     
     
         8 . The method of  claim 1 , further comprising, between said first oxidation stage and said second oxidation stage, an intermediate stage of filtration and washing of said nanotubes.  
     
     
         9 . (canceled)  
     
     
         10 . Opened carbon nanotubes produced by the method of  claim 1 .  
     
     
         11 . The method of  claim 3  wherein said acid is combined with said nanotubes in an excess amount.  
     
     
         12 . The method of  claim 4  wherein said nitric acid is combined in amount of 1 litre at a concentration on the order of 68-70% by weight.  
     
     
         13 . The method of  claim 7  wherein said second oxidation stage is performed in the presence of carbon dioxide at 500 to 550° C., for 1 hour to 1 hour 40 minutes.  
     
     
         14 . The method of  claim 10  wherein said nanotubes comprise a central channel which is filled with at least one conductive species.