Process for producing carbon-nanotube grafted substrate

Abstract

The present invention relates to a process for producing a carbon nanotube-grafted substrate, the process comprising: providing a substrate having catalytic material deposited thereon; and synthesising carbon nanotubes on the substrate by a chemical vapour deposition process in a reaction chamber; characterised in that the process comprises providing a counter electrode, applying a potential difference to the substrate in relation to the counter electrode and maintaining the potential difference of the substrate in relation to the counter electrode during the chemical vapour deposition process.

1 - 25 . (canceled) 
     
     
         26 . An apparatus for grafting carbon nanotubes to a substrate, the apparatus comprising a reaction chamber, means for positioning in the reaction chamber a substrate having catalytic material deposited thereon, a counter electrode, means for applying a potential difference to the substrate in relation to the counter electrode, heating means for heating the substrate in the reaction chamber and means for exposing the heated substrate to a carbon feedstock gas and a reductive gas while the potential is applied. 
     
     
         27 . The apparatus according to  claim 26 , further comprising an electrical source configured to be connected to the substrate, wherein the counter electrode is connected to the electrical source, such that during operation a capacitance circuit is formed with the substrate acting as one electrode of a capacitor and the counter electrode acting as the other electrode of the capacitor. 
     
     
         28 . The apparatus according to  claim 26 , comprising means for moving the substrate through the reaction chamber. 
     
     
         29 - 31 . (canceled) 
     
     
         32 . The apparatus according to  claim 28 , wherein the means for moving the substrate through the reaction chamber comprises a reel. 
     
     
         33 . The apparatus according to  claim 26 , further comprising a means for shielding the substrate from the counter electrode. 
     
     
         34 . The apparatus according to  claim 26 , wherein the substrate comprises a carbon-containing material. 
     
     
         35 . The apparatus according to  claim 26 , wherein the substrate comprises a fibre material. 
     
     
         36 . The apparatus according to  claim 26 , wherein the substrate comprises a carbon fibre material or precursor thereof. 
     
     
         37 . The apparatus according to  claim 26 , wherein the substrate is conductive. 
     
     
         38 . The apparatus according to  claim 26 , wherein the carbon nanotubes are multi-walled carbon nanotubes. 
     
     
         39 . The apparatus according to  claim 26 , wherein the reductive gas comprises hydrogen. 
     
     
         40 . The apparatus according to  claim 26 , wherein the carbon feedstock gas comprises carbon monoxide, a hydrocarbon or hydroxyl-substituted hydrocarbon, or a mixture of two or more of carbon monoxide, hydrocarbons or hydroxyl-substituted hydrocarbons, in gaseous form. 
     
     
         41 . The apparatus according to  claim 26 , wherein the catalytic material is a d-block transition metal-containing catalytic material or a non-metal seed catalyst, or a mixture thereof. 
     
     
         42 . The apparatus according to  claim 26 , wherein the catalytic material comprises iron (II) acetylacetone, iron (III) acetylacetone, nickel (II) acetylacetone, cobalt (II) acetylacetone, cobalt (III) acetylacetone, iron (III) nitrate, nickel (II) nitrate, cobalt (II) nitrate, cobalt (III) nitrate, or a mixture thereof. 
     
     
         43 . The apparatus according to  claim 26 , wherein the catalytic material comprises silicon oxide, silicon, silicon carbide, germanium, carbon, diamond, amorphous carbon aluminium oxide, zirconium oxide, carbon nanotubes or any other sp 2  carbon nanomaterial, or a mixture thereof. 
     
     
         44 . The apparatus according to  claim 26 , wherein the heating means is configured to heat the substrate in the reaction chamber to a temperature in the range of 400° C. to 1200° C. 
     
     
         45 . The apparatus according to  claim 26 , configured such that the application of the potential difference does not create a plasma. 
     
     
         46 . The apparatus according to  claim 26 , configured such that
 (a) the applied potential difference generates an electric field not exceeding 1 Vμm −1 ; and/or   (b) the current density on the cross section of the substrate does not exceed 50 Acm −2 ; and/or   (c) the current density on the counter electrode surface area does not exceed 10×10 −4  Acm −2 ; and/or   (d) the power density does not exceed 1 Wcm −3 .   
     
     
         47 . The apparatus according to  claim 26 , wherein the reaction chamber comprises a plurality of sequential zones, an aperture between each pair of adjacent zones, and means for supplying gas to each zone. 
     
     
         48 . The apparatus according to  claim 47 , wherein the plurality of zones comprise a reduction zone having an inlet coupled to a source of the reductive gas, in which the heated substrate is exposed to the reductive gas; and a synthesis zone having an inlet coupled to a source of the carbon feedstock gas, in which the heated substrate is exposed to the carbon feedstock gas, wherein the apparatus is configured to move a position on the heated substrate through the synthesis zone after moving the position on the heated substrate through the reduction zone.