MX2008000293A - Methods for growing and harvesting carbon nanotubes - Google Patents

Abstract

A method for directly growing carbon nanotubes, and in particular single-walled carbon nanotubes on a flat substrate, such as a silicon wafer, and subsequently transferring the nanotubes onto the surface of a polymer film, or separately harvesting the carbon nanotubes from the flat substrate.

Description

METHODS FOR THE GROWTH AND COLLECTION OF CARBON NANOTUBES FIELD OF THE INVENTION The present invention relates to the field of catalysts for the production of carbon nanotubes and methods for their use, and more particularly, but not by way of limitation, with single-walled carbon nanotubes, and with methods to produce polymers and other products that comprise carbon nanotubes. BACKGROUND OF THE INVENTION Carbon nanotubes (CNT) are uniform graphite sheet tubes with full layers of fullerene that were first discovered as concentric multi-layer tubes or multi-walled carbon nanotubes (MWNT, for example). its acronym in English) and subsequently as single-walled carbon nanotubes (SWNT, for its acronym in English) in present transition metal catalysts. Carbon nanotubes have shown promising applications including nanometer-scale electronic devices, high strength materials, electron field emission, scanning probe microscope tips, and gas storage. Generally, single-walled carbon nanotubes are preferred over multi-walled carbon nanotubes for use in these applications because Ref .: 189159 have smaller defects and are therefore stronger and more conductive than multi-walled carbon nanotubes of similar diameter. SWNT defects are less likely to occur than MWNT because occasional defects that form bridges between unsaturated carbon valences may appear in MWNTs, while SWNTs do not have neighboring walls to compensate for defects. BRIEF DESCRIPTION OF THE INVENTION The SWNT exhibit in particular chemical and physical properties that have a vast open number of potential applications. However, the availability of CNTs and SWNTs in particular in quantities and forms necessary for practical applications is still problematic. Large-scale processes for the production of SWNT are still necessary, and adequate forms of the SWNT are still needed for their application to various technologies. The present invention is directed to satisfy these needs. The patents and previous US applications directed to catalysts and production methods of carbon nanotubes, including U.S. Pat. No. 6,33,016, U.S. Pat. No. 6,413,487, the U.S. Publication Application. 2002/0165091 (Serial No. U.S 09 / 988,847), and Published Application 2003/0091496 (Serial No. U.S. 10 / 118,834), are hereby expressly incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE FIGURES Figure 1A shows a micrograph of the growth of carbon nanotubes on a flat substrate, and Figure IB shows a Raman spectrum of the carbon nanotubes of Figure 1A. Figure 2A shows a micrograph of the growth of carbon nanotubes on a flat substrate, and Figure 2B shows a Raman spectrum of the carbon nanotubes of Figure 2A. Figure 3A shows a micrograph of the growth of carbon nanotubes on a flat substrate, and Figure 3B shows a Raman spectrum of the carbon nanotubes of Figure 3A. Figures 4A, 4B and 4C are a schematic drawing showing the steps (A, B, C) of the polymer transfer of the carbon nanotubes from a flat surface. Figures 5A-5B-5C show a Raman spectrum of carbon nanotubes in three stages of polymer transfer of carbon nanotubes from a flat surface. Figures 6A-6B-6C show SEM images of SWNT produced on silicon wafers with a catalyst solution of different concentrations: (Fig. A) 0.38, (fig.b) 0.19%, (fig.c) 0.02%. The concentration is by weight of total metal. These charges correspond to the charges per metal area of (Fig. A) 16 micrograms / cm2, (fig.b) 8 micrograms / cm, and (fig.c) 0.8 micrograms / cm. Figures 7A-7B show the structural characterization of V-SWNT material removed from the silicon wafer without any purification, (fig.7b) Raman spectra of V-SWNT as produced with excitation lasers of wavelengths of 633 nm (solid line) and 488 nm (dotted line). Figures 8A1-8A2-8B1-8B2-8C1-8C2 show the side-by-side comparison of SEM images (left column) of SWNT with AFM images (right column) of corresponding silicon wafers with catalyst solution of different concentrations: (Figures 8A1-8A2) 0.02% by weight, 0.19% by weight, (Figures 8C1-8C2) 0.38% by weight. The concentration (% by weight) refers to the total metal month. The AFM images were obtained after the silicon wafers were calcined in a 500 ° oven. All scale bars in the SEM images are 50 nm and the widths of the AFM three-dimensional frames are 1 μm except the one in panel a2, which is 5 μm. Figure 9 shows a schematic diagram illustrating the proposed growth mechanism of third-order structures of V-SWNT: from left to right is the first-order structure of a single tube, the second-order structure of a beam, and the Third order structure, which can be 2D (xy) lawn or ID (z) forest.

Figures 10A1-10A2-10B1-10B2 show SEM images of ordered arrays of SWNT with a fast-drying process pattern (10al-10a2) and grid-masked splash coating (10bl-10b2). The images were taken with minor (1) and greater amplification (2). Figure 11 is a schematic representation of a continuous process of growth and collection of carbon nanotubes from flat surfaces. Figure 12 is a schematic representation of an alternate continuous process of growth and collection of carbon nanotubes from flat surfaces. Figure 13 shows SEM images of V-SWNT on detaching from the flat surface directly in air. (TO) SEM image of V-SWNT attached to the flat surface; (B) SEM image of V-SWNT detached from the flat surface. Figure 14 is a TEM image of V-SWNT showing the absence of metal impurities. Figure 15 shows XANES spectra of V-SWNT at different incident angles with respect to the upper surface of V-SWNT. Figure 16 shows graphs with experimental data and adjusted peak intensity sigma * and pi *. Figures 17A-17B show SEM micrographs of top (Fig. 17A) and side (Fig.l7B) views of a typical V-SWNT sample by SEM. Figure 18 shows V-SWNT images obtained for a series of reaction time periods. The bars with scales in these images are 1 μm for 0, 30, 60 seconds and 3 minutes, 2 μm for 10 minutes and 5μ for 30 minutes. Figure 19 shows Raman spectra of V-SWNT obtained for a series of reaction time periods: 0.5 minutes, 3 minutes and 10 minutes from bottom to top. These 3 curves are normalized with respect to the Si band at 520 cm "1. The insertion is the G band of V-SWNT obtained for 0.5 minutes (solid line and 10 minutes (dotted line) respectively when normalized with respect to the G band. DETAILED DESCRIPTION OF THE INVENTION The present invention contemplates methods of producing films carrying CNT and preferably films carrying SWNT, on flat surfaces (flat substrates) such as silicon wafers having small amounts of catalytic metal, for example cobalt and molybdenum, disposed thereon The carbon nanotube-polymeric film nanotube compositions produced herein may be used, for example as, electronic field emitters, filled with polymers in any product or material in which an electrically conductive polymer film is useful or necessary for production.The growth of CNT on flat surfaces can be removed from the flat surface by different means (including, but not limited to, detachment as in the examples, cutting, sonication, and guimic engraving of the flat surface) resulting in high purity CNT which can be used for any CNT application. The flat surface material-CNT could also be used in applications such as sensors, interconnects, transistors, field emission devices, and other devices. The flat substrates of the present invention include substrates having continuous surfaces (not as particles) which may be completely planar (planar) or may have a curvature that includes convex and concave surfaces that have one or more pits in them. They may also have a certain roughness, which is small in relation to the macroscopic scale of the substrate. Materials having flat surfaces contemplated for use as flat substrates or support material for the catalysts described herein, may include or may be constructed (but not limited to): wafers and sheets of SiO, Si, organometallic silica, wafer If you put doped are or without a layer of Si2, Si3N4, Al203, MgO, quartz, glass, oxidized silicon surfaces, silicon carbide, ZnO, GaAs, GaPGaN, Ge, and InP, sheet metal such as iron, steel, stainless steel, and molybdenum, and ceramics such as alumina, magnesia and titania. The catalytic materials used in the present invention are prepared in a manner by depositing different metal solutions of specific concentrations on the flat substrate (e.g., a silicon wafer). For example, Co / Mo catalysts can be prepared by impregnating several silicon wafers with aqueous solutions of cobalt nitrate and ammonium heptamolybdate (or molybdenum chloride) to obtain the bimetallic catalysts of the chosen compositions (See U.S. Patent 6,333,016, the entirety of which is expressly incorporated by reference herein). The total metal filler is preferably 0.001 to 1000 mg / cm2. After the deposition of the metal, the flat catalytic substrates are preferably first dried in air at room temperature, then in an oven at 100 ° C-120 ° C for example, and finally in air flow at 400 ° C-600 ° C . Carbon nanotubes can be produced on these catalytic substrates in different reactors known in the art such as packed bed reactors, structured catalytic reactors, or moving bed reactors (for example, having the catalytic substrates placed on a transport mechanism such as the systems described for example in more detail in Example 6. Flat catalyst substrates may optionally be pre-reduced (for example, by exposure to H2 at 500 ° C, for example, at a temperature up to the reaction temperature) before that the flat catalytic substrate is exposed to the reaction conditions Before exposure to a gas containing carbon (eg, CO) the flat catalytic substrate is heated in an inert gas (eg, He) to the temperature of reaction (600 ° C-1050 ° C) Then a gas containing carbon (for example, CO) or gasified liguid (for example) is introduced. ethanol) After the given reaction period which is in the range of 1 to 600 min., the flat catalyst substrate with CNT thereon is cooled to a lower temperature such as room temperature. For a continuous or semi-continuous system, the pretreatment of the flat catalytic substrate can be carried out in a separate reactor, for example, for pretreatment of fairly large quantities of flat catalytic substrate with which the flat catalytic substrate can be stored for later use in the unit. production of carbon nanotubes. In one embodiment of the invention, the planar catalytic substrate electively produces SWNT by the disproportionation of CO (decomposition at C and C02) to a preferred temperature range of 700-950 ° C (see US Serial No. 10 / 118,834, which is expressly incorporated herein by reference in its entirety). The solutions of catalytic precursors used for the application of catalytic coatings to the flat substrates of the present invention preferably comprise at least one metal from Group VIII, from Group VIb, from Group Vb, or rhenium or mixtures having at least two of those metals . Alternatively, the catalyst precursor solutions may comprise rhenium (Re) and at least one Group VIII metal such as Co, Ni, Ru, Rh, Pd, Ir, Fe and / or Pt. The Re catalyst (Group VIII may comprise in addition a Group VIb metal such as Cr, W, or Mo, and / or a Group Vb metal, such as Nb. Preferably the catalytic precursor solutions comprise a Group VIII metal and a Group VIb metal, for example, Co and Mo. Where the phrase "an effective amount of a gas containing carbon" is used herein means a gaseous species of carbon (which may have been liquid before heating to the reaction temperature) present in sufficient amounts. to produce the deposit of carbon on flat catalytic surfaces at elevated temperatures, such as those described herein, resulting in the formation of CNT thereon.As shown herein, the flat catalytic substrates as shown in FIG. they write herein include a metal catalyst composition deposited on a flat support material. The ratio of the Group VIII metal to Group VIb metal and / or Re and / or Group Vb metal in the catalytic materials may affect the performance, and / or the selective production of SWNT as indicated elsewhere herein. The molar ratio of the Co (or other Group VIII metal) to Group VIb metal or other metal is preferably from about 1:20 to about 20: 1; more preferably from about 1:10 to about 10: 1; even more preferably from 1: 5 to about 5: 1; and additionally including ratios of 1: 9, 1: 8, 1: 7, 1: 6, 1: 5, 1: 4, 1: 3, 1: 2, 1: 1, 2: 1, 3: 1, 4 : 1, 5: 1 6: 1, 7: 1, 8: 1 and 9: 1, inclusive. Generally, the concentration of the metal Re, when present, exceeds the concentration of the Group VIII metal (e.g., Co) in solutions of catalytic precursors and catalytic compositions employed for the selective production of SWNT. The solution of catalytic precursors is deposited preferably on a flat support material (substrate) such as a silicon wafer as indicated above or other flat materials known in the art and other supports as described herein whenever the materials have a flat surface, as described herein. Preferably, the solution of catalytic precursors is applied in the form of a liquefied precursor (catalyst solution) on the flat substrate. Examples of suitable gases containing carbon and gasified liquids which may be used herein include hydrocarbons, both saturated and unsaturated, such as methane, ethane propane, butane, hexane, ethylene, and propylene; carbon monoxide; oxygenated hydrocarbons such as ketones, aldehydes, and alcohols including ethanol and methanol; aromatic hydrocarbons such as toluene, benzene and naphthalene; and mixtures of the foregoing, for example carbon monoxide and methane. The carbon-containing gas can optionally be mixed with a diluent gas such as helium, argon or hydrogen or a gasified stream such as water vapor. The preferred reaction temperature for use with the catalyst is between about 600 ° C and 1200 ° C; more preferably between about 650 ° C and 1000 ° C; and much more preferably between 750 ° C and 900 ° C. In one embodiment, the SWNT may comprise at least 50% of the total CNT product produced on the flat catalytic substrates. In addition, the SWNT may comprise 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97.5%, 98% or 99% of the total CNT product. In an alternate modality, MWNTs may comprise at least 50% of the total CNT product. In addition, MWNTs may comprise 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97.5%, 98% or 99% of the total CNT product. In an alternate embodiment, double-walled CNTs may comprise at least 50% of the total CNT product.

In addition, double-walled CNTs can comprise 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97.5%, 98% or 99% of the total CNT product. In other embodiments, the CNT product may comprise a mixture of SWNT, double walled CNT, and MWNT.

While the invention will now be described in connection with certain preferred embodiments in the following examples in such a way that aspects of it can be understood and appreciated, it is not intended to limit the invention to these particular embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents which may be included within the scope of the invention. Therefore, the following examples, which include preferred embodiments, will serve to illustrate the practice of the present invention, it being understood that the features shown are by way of example and only for purposes of illustrative discussion of preferred embodiments of the present invention and are presented with the purpose of providing or believing in the most useful and easily understandable description of the formulation procedures as well as the principles and conceptual aspects of the invention. EXAMPLE 1: Growth and Collection of SWNT (1) Solution of Catalytic Precursors (to prepare the catalytic composition) Cobalt solution: dissolve 0.3100 g of cobalt nitrate in a solvent such as isopropanol to make the total weight equal to 23.75 g . , resulting in a Co concentration of 0.0442 mmol / g. Molybdenum salt solution: add 1 g of DI water (deionized) to 0.9058 g of molybdenum chloride under a cabin, shake well to make sure all the molybdenum chloride dissolves to form a brown solution. Dilute the solution with a solvent such as isopropanol to 25 g resulting in a Mo concentration of 0.1326 mmol / g. Mix the Co and Mo solutions in equivalent weights and add 5% of a humidifying agent such as tetraethyl orthosilicate or another solvent described below. Other catalytic metals may be used as indicated above, including those of Group VIII, Group VIb, Group Vb, and Re. Solvents that can be used to dissolve catalytic metal components include, but are not limited to, metal, ethanol, isopropanol, and other alcohols, acetone, other organic solvents, acids, and water , depending on the solubility of the metal precursors and the stability of the humidifying agent. Other wetting agents include, but are not limited to, silicates, silanes, and organosilanes, including polysiloxanes, polycarbosilanes, organosilazanes, polysilazanes, siloxanes derived from alkoxides, allyl-cyclosiloxanes, alkyl-alkoxy silanes, poly-alkyl-siloxanes, amino-alkyl -alkoxy-silanes, and alkyl-orthosilicates. A catalyst stabilizer may be included and the group may be selected including, but not limited to: silicates, silanes, and organosilanes including polysiloxanes, polycarbosilanes, organosilazanes, polysilazanes, siloxanes derived from alkoxides, alkyl-cyclosiloxanes, alkyl-alkoxy silanes, poly-algil-siloxanes, amino-alkyl-alkoxy-silanes, or alkyl-orthosilicates, as well as organotitanates, such as titanium alkoxides or titanoxanes; organic aluminoxy compounds, organ zirconates, and organomagnesium compounds (including Mg-alkoxide). The solution of catalytic precursors (e.g., Co, Mo) can be prepared and used immediately, or prepared and stored for later use. (2) Deposit of the Catalytic Precursor Solution (for example, Co / Mo) on Silicon Wafers (Flat Substrates) - DSD (Drip-Disperse-Dry) Process The deposit process in this example involves dripping a small amount of the solution of catalytic precursors on the flat substrate. The solution (coating) is dispersed on the substrate to form a uniform layer on it and dried rapidly forming the catalytic composition on the flat catalytic substrate. Alternatively, the catalyst precursor solution may be applied to the substrate movable substrate support system via spray, coating, spin coating, dipping, screen printing, or other methods known in the art. Also, the drying process can be done slowly, leaving the flat substrate to stand at room temperature and covered to maintain a higher relative humidity and less circulation of air exposed to the air. (3) Thermal Pretreatment of the Flat Catalytic Substrates The silicon wafer of Co / Mo (flat catalytic substrate) produced in this way can be further dried in an oven at 100 ° C for 10 minutes, then calcined in air at 500 ° C ( or 400 ° C-600 ° C for 15 minutes in a muffle.

The calcined flat catalytic substrate was placed in a 2.54 cm (1 inch) diameter quartz reactor, parallel to the direction of gas flow and reduced by 1,000 cm 3. standard / min of pure H2 at 500 ° C, with a heating ramp from room temperature to 500 ° C in 40 minutes and kept at that temperature for an additional 5 minutes. Then, the feed to the reactor was changed to pure He and the temperature was raised to 750 ° C at a rate of 10 ° C / min. The calcination can be carried out immediately after drying or after leaving the dry flat catalytic substrate in storage for several days. The calcination temperature can vary from 300 ° C to 650 ° C and the calcination time from 1 to 30 minutes. Alternatively, the reaction temperature can be varied between 400 ° C to 850 ° C and the reaction time of 1 to minutes. The heating process can use either a ramp from 1 to 100 ° C / min, or by introducing the sample into a preheated zone. (4) Production of SWNT on the flat catalytic substrate a) The reduced plane catalytic substrate was exposed to a flow of 1,000 cm3 standard / min of pure CO at 750 ° C. The reaction remained for 30 minutes under 718 Pa (15 psi) of pure CO. b) After the reaction, the system was maintained at the same temperature for 30 minutes under He flow and was finally cooled to room temperature under He. The speed of the CO gas can vary between lcm / min and 10 / min (standard conditions); with flow regimes from laminar to turbulent. Flow patterns can be altered by the use of deflectors or pits. Alternatively, the feed could be selected from methane, ethane, ethylene, ethanol, or other materials as described elsewhere herein. Also, gases that are fed together such as water, oxygen, or hydrogen can be employed. (5) Transfer of SWNT from the flat catalyst substrate to another medium a) After step 4, a mixture of polydimethylsiloxane prepolymer (PDMS) (Sylgard-184) and a crosslinking agent was deposited on the SWNT / substrate surface catalytic plane. The weight ratio of PDMS to crosslinking agent was 10: 1. b) The wafer (ie SWNT / flat catalytic substrate) is polymeric film was then sent to an oven to cure for 2 h at 60 ° C. After cooling, the resulting polymeric film containing SWNT was peeled off from the silicon wafer (flat catalyst substrate). The Raman characterization on the surface of the Si wafer and the polymer surface indicated that the transfer of SWNT to the polymer was practically (substantially) complete. Examples of polymers that can be applied to the flat catalytic substrate with SWNT included therein include, but are not limited to: polypropylene, polyethylene, polyacrylamide, polycarbonate, polyethylene terephthalate (PET), polyvinyl chloride, polystyrene, polyurethane, Teflon, Saran, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate (PMMA), polyacrylates, poligro rubber, polyesters , and polyamides such as nylon, as well as polymers formed in situ for example by crosslinking prepolymers applied to the flat catalyst substrate carrying nanotubes (for example, as shown in the example). Similarly, the transfer medium could be a metal instead of a polymer. In this case, a metal film could be applied over the CNT by different methods, such as ion bombardment or evaporation. The metal film could subsequently be welded to another metal to make electrical contacts, change surface properties, change heat conduction, and dynamic dynamic properties, for example. The transfer of CNT from the flat catalytic substrate to the transfer medium can take two possible configurations. In the first, the SWNT are completely embedded in the matrix applied to the flat catalytic substrate and in the second, the transfer medium only covers a fraction of the CNT structure and after the transfer, part of the CNTs remain exposed. The scheme shown below illustrates a brush-like structure. However, the concept is not limited to this particular structure, but applies to any other in which a portion of the CNT remains exposed. EXAMPLE 2 (A) SWNT Growth on Flat Catalytic Substrates that Form Two-Dimensional Arrangements Effects of Gas Pressure on the SWNT Density on the Catalytic Substrate The SWNT grew on the surface of Co-MO / wafer for 30 minutes at 750 ° C , under different CO pressures. The planar catalytic substrates (wafers) were prepared following the recipe described in Example 1. The resulting CNT structures, observed by scanning electron microscopy (SEM), are illustrated in Figures 1 and 2. The figure The sample shows the SWNT growth at a lower pressure (718 Pa gauge (15 psig)) and shows a lower density of SWNT than in Figure 2A, which shows a higher density of SWNT obtained at higher pressure (3.830 Pa gauge (80 psig)). The corresponding spectra (Figures IB and 2B) provide clear evidence for the presence of SWNT; that is, bands of strong breathing mode (at 200-300 cm "x), characteristic of the SWNT), acute G bands (1590 cm" 1) char characteristics in the sp2 configuration, and minor D bands (1350 cm) "1), characteristics of disordered coal in the sp3 configuration. (B) Effects of the Co / Mo Concentration on the SWNT Density on the Catalytic Substrate The SWNT grew for 30 minutes under CO (P = 15 psig) at 750 ° C on two surfaces with different charges of Co / Mo catalytic metal In figure 1A, the metallic charge of Co / Mo on the Si wafer was 16 mg / cm2 The SWNT that grew on it had a low density As shown in Figure 1A, in Figure 3A, the metallic charge of Co / Mo on the Si wafer was 32 mg / cm 2. The SWNT that grew on it had a high density as shown in Figure 3A. With respect to the results in (A), the Raman analysis (Figures IB and 3B) clearly shows the presence of SWNT, with bands of strong breathing mode (at 200-300 cm "1), characteristic of the SWNT, an acute G-band (1590 cm" 1) characteristic of ordered carbon, and a lower D-band (1350 c "1), characteristic of disordered coal EXAMPLE 3 (A) Transfer of SWNT from the Flat Catalytic Substrate onto a Transfer Medium In one embodiment of the invention, after which the SWNTs are formed the flat catalytic substrate having catalytic material thereon is transferred onto a transfer medium comprising a polymeric film or other material (eg, metal, ceramic, disordered film, elastomer, or carbon) deposited on the flat catalytic substrate which carries the SWNTs (see Example 1, Step 5) The transfer means may have an adhesive material thereon to improve the adherence of the SWNTs thereon. The transfer process is shown in Figures 4A, B and 4C. Figure 4A shows a flat substrate 10 having a catalytic surface 20 thereon, and a mass of SWNT 30 present on the catalytic surface 20. A transfer medium 40 (e.g., a polymeric material) is applied to the catalytic surface. 20 of the flat substrate 10 and on the mass of SWNT 30 (Figure 4B), where the transfer medium 40 is allowed to cure (if necessary), thereby causing the transfer and adhesion or trapping of most of the mass from SWNT 30 to it. The transfer medium 40 and the mass of SWNT 30 transferred thereto can be removed from the catalytic surface 20 (Figure 4C). There is a residual mass 50 of SWNT remaining on the catalytic surface 20 after most of the mass of SWNT 30 is removed therefrom. (B) Characterization of the Si Wafer and Polymer Waves Demonstrating the Transfer: Figures 5A-5C illustrate the different steps with the corresponding Raman spectrum obtained after the SWNT mass is transferred. Figure 5A shows Raman spectra of the mass of SWNT 30 before transfer. This spectrum shows the clear footprint of the high quality SWNT; that is, a strong G band, a weak D band and clear bands of breathing mode. Figure 5B shows a Raman spectrum of the SWNTs on the polymeric material 40 after forming a film on the Si wafer containing SWNT and detaching it. The Raman spectrum shows that a large fraction of the mass of SWNT 30 has been transferred onto the polymeric material 40. All the characteristic qualities of the SWNT are clearly seen on the polymer material 40. Figure 5C shows a Raman spectrum of a small residue of SWNT that remained on the catalytic surface 20. As an internal calibration of the amount of SWNT on the surface of the Si wafer, the relative intensities of the Si band and the carbon band can be noted (for example, the G band a 1590 cm "1) EXAMPLE 4 (A) Influence of the Catalyst Load on the Morphology of SWNT Formations: Production of Vertically Oriented SWNTs on the Si Flat Substrate Following the preparation procedures described in Example 1, the solutions of Catalytic precursors of varying concentration of metals (0.001-3.8% by weight) were prepared by dissolving Co and Mo salts in isopropanol, while maintaining a correlation Co mole: Mo constant 1: 3. The subsequent steps were identical to those of Example 1. The SWNT as produced on the flat substrate was characterized by Raman spectroscopy electron microscopy (SEM and TEM), and probe microscopy (eg, AFM). Figure 6A-6C illustrates the dramatic effect of the catalyst chart on the morphology resulting from the SWNT formations. This reproducible trend demonstrates without a doubt that the concentration of the catalyst solution affects the type of SWNT growth on the flat substrate. The SEM images clearly show that vertically aligned SWNTs (V-SWNT forest) of almost 40 microns in length grew on the substrate impregnated with the catalytic precursor solution of 0.19% by weight of the total metal concentration (Co-Mo) (Figure 6B). By contrast, on the wafers impregnated with solutions of catalytic precursors of 0.38% by weight (figure 6A) and 0.02% by weight (figure 6C), two-dimensional random networks of SWNT (turf) were observed after the reaction. The sample with the highest metal concentration (0.38% by weight) produced a higher density of nanotubes than the lower metal concentration (0.02% by weight), but none of them resulted in vertical growth under the conditions used in this example. The results indicate that there is an optimal surface concentration of metals that results in vertical growth. In addition, it was observed that the growth of "SWNT turf" with solution of catalytic precursors of the highest concentration (0.38% by weight) was reasonably denser than with the solution of catalytic precursors of lower concentration (0.02% by weight). Other concentrations were studied with higher loads (up to 3.8% by weight) or lower (0.001% by weight), but none of them produced SWNT vertically aligned. In fact, the very high concentration (3.8% by weight) resulted in the formation of carbon fibers and multiwall carbon nanotubes, while the lower concentration of catalyst (0.001% by weight) produced thin sets of SWNT in its mostly scattered. (B) Structural Analysis The structural characteristics of the nanotubes that make up the "forest" and "turf" formations observed by SEM were further evaluated by Raman and TEM spectroscopy (Figures 7a-7b). Raman spectroscopy is a well-known method for assessing SWAT quality based on the relative intensity of D and G bands. TEM provides direct identification of the nature of carbon species deposited on the surface (ie, SWNT, MWNT , amorphous or nanofibers). The Raman spectra (as shown in Figure 7b) of the V-SWNT forest as it was produced were obtained with two excitation lasers (633 nm and 488 nm). The very low D / G ratio is consistent with high quality SWNTs with a low concentration of defective nanotubes or disordered carbon species (eg, nanofibers). At the same time, it is well known that the frequency of the radial breathing mode bands (RBM) is inversely proportional to the diameter of the nanotubes, according to the expression omegaRBM = 234 / ÓSWNT + 10 [cm "1]. Spectra for the V-SWNT sample obtained with three different lasers showed that the RBM bands cover a wide range of frequencies (from 130 cm "1 to 300 cm" 1), which corresponds to a range of diameters of 0.18-1.9 nm, a much wider distribution than that typically obtained by the method of use of Co-Mo catalysts on high silica. Superficial area. The wide distribution of diameters is also reflected in the convergence of the G ~ and G + characteristics and the broad base of the G-band, in contrast to the sharper lines and the steeper separation of the G ~ and G + contributions for the band G in the CoMoCAT material. The TEM observations of the V-SWNT taken directly from the substrate without any purification indicated the presence of nanotubes of varying diameters (Figure 7a) in accordance with the Raman spectra (Figure 7b). At the same time, TEM provided ample evidence of the purity of the V-SWNT as prepared, free of other forms of carbon. To explore the relationship between the metallic charge on the flat substrate and the morphology resulting from the SWNT formations, we use atomic force microscopy (AFM), a powerful tool that provides three-dimensional profiles of surfaces. By investigating the morphology of the catalyst surface before the growth of the nanotubes, we were also able to identify the optimal distribution of particles that result in the forest of V-SWNT. This analysis is illustrated in Figures 8A1-8A2-8B1-8B2-8C1-8C2 which contrast with high amplification SEM images of the SWNT arrays and AFM images of calcined catalysts / substrates for three different metal charges. The AFM image in Figure 8al clearly shows that the catalyst particles generated from the impregnation solution with the low metal concentration (0.02% by weight) were sticky and scarce. From this metal distribution a similarly sparse formation of two-dimensional SWNT turf was obtained (Figure 8a2). In the case of the intermediate metal concentration (0.19% by weight), the AFM in Figure 8bl evidences a dense population of nanoparticles of relatively uniform size. The average distance between these particles was around 60-70 nm. It should be noted that the TEM / EDXA analysis, as well as the XPS analysis of angular resolution, showed that not all Co and Mo added remained exposed on the surface. Rather, a fraction of them was buried in the layer of the product silica resulting from the decomposition of the catalyst stabilizer and the humidifying agent during the heat treatment. The SEM image of Figure 8b2 shows that this distribution succeeds in promoting V-SWNT forest formation. Interestingly, the density of sets of nanotubes is approximately the same as the density of catalyst particles observed by AFM before growth, which suggests that essentially every particle of catalyst is active for the production of nanotubes. In contrast, in the case of the metal concentration of 0.38% by weight as shown in Figure 8c2, some larger alloy particles formed on the flat surface and possibly generated larger cobalt clusters that were not suitable for nucleation of SWNT, while a small fraction of Co clusters with the optimal size for the growth of SWNT remained among the larger ones. Therefore, a thicker layer of SWNT grass grew as shown in Figure 8cl. In another remarkable observation, it is observed that the carbon deposits of a V-SWNT were observed directly perpendicular to the surface, a random network of SWNT sets is clearly evident over the top of the forest, while the observation at different angles shows clearly the well-aligned structure shown in Figure 8bl. There is no doubt that, in this case, a root growth mechanism is operative. Therefore, the fraction of nanotubes that is observed on top of it has formed during the first stages of the reaction, whereas the ordered growth (vertically oriented) only occurs later, evidently restricted by the presence of the two-dimensional cortex formed in the initial stages. Initially, a randomly arranged SWNT layer grows from a loose network to a dense network (see Figure 9). The density of this network depends on the surface concentration of the catalyst. With a low catalyst concentration only a loose structure is formed. In contrast, in a region with the appropriate catalyst density a dense array of nanotubes forms a crust (a horizontal layer of randomly oriented carbon nanotubes) that constitutes a rather solid structure. This bark is then lifted by the nanotubes that grow from the bottom (see Figure 8bl). This is the reason why, although each individual nanotube is not perfectly straight and not necessarily every nanotube has the same length, the forest in general has a smooth upper surface. EXAMPLE 5: Production of Vertically Oriented SWNT Patterns on the Flat Substrate To further demonstrate the effect of the distribution of catalyst particles on the growth of SWNT on flat substrates, in addition to the uniform growth of nanotubes on uniform catalyst films described in Example 4, they prepared nanotube films with patterns by two different methods. In one of the methods, the patterns appeared naturally and in the other, the patterns were controlled. The natural standards were formed when a thin film of wet catalyst was dried at a rapid drying rate. This method resulted in separate circular droplets of catalyst distributed on the Si substrate. In contrast, the formation of the controlled pattern was performed using a mask and bombarding an AuPd film on a homogeneous preformed catalyst film, prepared by slow drying and calcined in air. In this form, the catalyst fraction covered by the Au-Pd alloy was selectively deactivated and the growth of nanotubes on those regions did not take place. As a result, the nanotube forest only grew from the remaining areas of active catalyst. The SWNT as produced on catalyst / wafer were characterized by Raman spectroscopy, electron microscopy (SEM and TEM), and probe microscopy (AFM). In the case of the natural pattern, rapid drying in the air resulted in microscopic circular areas with a varying concentration of catalyst. For the manual process, a TEM grid was used as a mask to protect the previously deposited Co-Mo catalyst. The fraction of the surface that was not covered by the grid was deactivated by means of an Au / Pd film bombarded on the surface. The resulting grown pattern of V-SWNT obtained by the two methods is illustrated in figures 10O-10a2-10bl-10b2. Figure 10 shows SWNT arrangements in the form of a volcano on the patterned substrate by means of the rapid drying method. A cross-sectional image of these higher amplification volcanoes (Figure 10a2) shows that they comprise SWNT aligned vertically near the edge of the ring, with two-dimensional random arrays ("lawn") in the middle part. The image (Figure 10a2) shows parallel V-SWNT bars grown over the area of activated catalyst defined by the TEM grid. Due to the diffusion of Au-Pd from the edge to the space between the grid and the surface, there is a gradient of catalyst concentration in the edge area. As a result, the forest in this area bends to the outside with the bark on the top extending continuously to the lawn attached to the substrate.

EXAMPLE 6 System for the Continuous Production of Carbon Nanotubes on Flat Substrates In an alternative embodiment, the SWNT can grow on flat substrates 100 (as defined elsewhere herein) in a continuous process, shown for example in Figures 11 and 12. The flat substrates 100 are applied to a transport assembly 110 in such a way that the conveyor belt can move directionally in a continuous manner. A catalyst 120 precursor solution can be applied to the flat substrates 100 by means of a spray mechanism 130 or by other application means including the use of slotted dies, rods, engravings, blades, on roll and reverse roll thus forming flat catalytic substrates 100. As shown for example, the furnaces 140, 150 and 160 can be located in such a way that the transport assembly 110 can transport the flat catalytic substrates 100 to a reaction zone 170 for sequential calcination and reduce the flat catalytic substrates 100. to make them catalytically more active causing the growth of nanotubes at variable temperatures. For example, at the inlet 180, air can be introduced into the reaction zone 170 to calcine the flat catalytic substrates 100 in the oven 140, and H2 can be introduced into the inlet 190 in the reaction zone 170 to reduce the planar catalytic substrates 100 in the furnace 150. A carbon containing gas such as CO or ethanol can then be introduced into the reaction zone 170 at the inlet 200 for supplying the carbon containing gas for the catalytic nanotube production process in the furnace 160. When the flat catalytic substrates carrying SWNT 210 leave the furnace 160 with SWNT thereon, the SWNTs can be collected from these for example by means of a knife 230 or other methods not shown, including but not limited to, passing the tape through a tank and using sonication to promote the release of the tubes by subjecting the nanotube field to a cutting field (gas or liquefied) or contacting a tape / weft / plate covered with nanotubes with a sticky material. The gases can be removed or recycled from the reaction zone 170 (to be reused or to have byproducts removed from it) via exits 185, 195 and 205, for example. The flat catalytic substrates 100 which have been collected from the SWNT 220 can then be removed from the transport assembly 110, for example, by passing them through a recirculation unit 240 or simply the catalyst composition 120 can be removed therefrom. The new flat substrates 100 can then be applied to the transport assembly 110 or a new, catalytic precursor solution 120 can be applied to the flat substrates 100 which remain on the transport assembly 110. Alternatively flat catalytic substrates carrying SWNT 210 could be used in the a process described elsewhere herein to produce transfer media (eg, polymeric films) with CNT embedded therein (see examples 1-3). The solution of catalytic precursors 120 on the flat substrate 100 can be patterned through printing, photolithography, or laser writing, for example after spraying, or in place of spraying. The preparation and conditioning of the catalyst precursor solution 120 can be done offline. In Figure 12 an alternate version of the invention is shown, similar to the embodiment of Figure 11, which comprises a plurality of flat substrates 100a which are disposed on and secured to a transport assembly 110a.

A solution of catalytic precursors 120a, as described above, is applied to the flat substrates 100a, via, for example, a spray mechanism 130a, or any other applicable method (before or after the flat substrates 100a are applied to the assembly transport 110a). The transport assembly 110a transfers the flat catalytic substrates 100a to the furnace 140a in a reaction zone 170a which receives air via the inlet 180a for calcining the flat catalytic substrates 100a, which are transferred to the furnace 150a which receives a reducing gas from the inlet 190a to reduce the flat catalytic substrates HOd which are then transferred to the furnace 160a, which receives from the reaction zone 17Ca and an entry 200a a carbon containing gas as discussed on either side herein to cause the formation of the SWNT or CNT on the flat catalytic substrates 100a to form flat catalytic substrates carrying SWNT 210a having SWNT 220 about them. The SWNTs 220a are then removed by means of a blade 230a or by other means as discussed elsewhere herein. The flat catalytic substrates 100a remain on the transport assembly 110a and are used one or two additional times to form SWNT before being recycled or removed and replaced. The flat catalytic substrates 100a remaining on the transport assembly 110a can finally be treated or cleaned to remove the catalyst precursor solution 120a, and left on the transport assembly 110a or can be completely removed therefrom and replaced with the new flat substrate 100a, manually or automatically. Other alternatives of a continuous belt that may be used include roller-to-roll (unwinding and winding) or continuous feeding of flat substrates or plates traveling on a conveyor belt. In alternate embodiments, an annealing step may be included to take place before releasing the SWNTs from flat catalytic substrates carrying SWNT 210 or 210a. In addition, a functionalization step may occur before the SWNT is released, for example, by radiation or plasma. The product resulting from this process could be either the SWNT itself or the SWNT attached to the flat substrates. EXAMPLE 7 Removal of SWNT in Liquids When the SWNT produced on the flat catalytic substrates have to be transferred to a liquid medium, it is convenient to transfer them directly from the flat catalytic substrate to the liquid, thus avoiding intermediate stages. This transfer to a liquid medium can be achieved by immersing the flat catalytic substrate carrying SWNT in a surfactant solution. In a simple experiment, a piece of 2 cm x 1 cm of silicon wafer carrying V-SWNT was placed in a vial containing 7 ml of 1.3 mmol / l of NaDDBS solution. Other surfactants can be used. After sonication of the sample for 1 minute in a sonicator bath, the V-SWNT film was peeled off and the silicon wafer was removed from the surfactant solution. If a good dispersion of the nanotubes in the liquid medium is required, sonication by horn can be used to break the nanotube assemblies after the wafer has been removed from the surfactant solution. Horn sonication of the surfactant solution with the piece of wafer still inside can result in contamination of the sample with particles coming from the substrate. Similar experiments were performed using other surfactants including: sodium cholate, NaDDBS, CTAB and SDS; and other solvents including: isopropanol, chloroform, dichlorobenzene, THF and different amines. Alternative surfactants that could be used include, but should not be limited to: Surfynol CT324, Aerosol OS, Dowfax 2 I, Dowfax 8390, Surfynol CT131, Triton X-100, Ceralution F, Tween 80, CTAT and Surfonic L24-7. Other compounds such as polysaccharides (e.g., sodium carboxymethylcellose) as a "surfactant" to change the humidification capacity of the surface or improve the dispersibility of the SWNT in the liquid medium. As an alternative to surfactant solutions, other solvents that may be used include, but are not limited to, alcohols, ketones, aldehydes, ethers, esters, alkanes, alkenes, aromatic hydrocarbons, and mixtures thereof. In some cases the sonication bath may not be required to remove the V-SWNT film from the flat substrate and the V-SWNT film could come out by itself after it has been submerged in the solution or after leaving the liquid flow in the part. top of the V-SWNT movie. In some other cases, agitation or gentle agitation may be used as an alternative to the sonication bath. An alternative method to transfer the V-SWNT to a liquid medium is to apply a liquid film to the top of the V-SWNT material, reduce the temperature in order to freeze the liguid, mechanically remove the frozen liquid containing the V -SWNT and mix the frozen liquid containing the V-SWNT with more liquid. Alternatively, other CNTs, including SWNT or MWNT not vertically oriented could be suspended using these methods. EXAMPLE 8 Removal of SWNT in vacuum / air Nanotubes produced on flat substrates can be removed from the flat catalytic substrate directly in air using several simple methods, such as sweeping the surface with a soft spatula or blade or peeling the film from the flat substrate (see Figure 13). In general, it was observed that by increasing the thickness of the nanotube film, it was easier to remove the nanotube material. The XPS analysis on the flat catalytic substrate used for nanotube growth and the TEM and EDXA analyzes of the V-SWNT material after it was detached from the catalytic substrate showed that most of the catalytic metal (Co and Mo) remained on the flat catalytic substrate while the nanotube material was free of metallic impurities (see Figure 14), and therefore did not pull catalytic material from the flat substrate during the removal of the CNTs. Alternatively, vibrations or a turbulent gas stream could be used to induce separation of the nanotube material from the planar substrate. The described methods could be used either in air, any other gas or vacuum. The described methods could be performed with the sample at room temperature or after the sample has been heated above room temperature or cooled below it. EXAMPLE 9 Vertical Alignment of SWNT during Growth on Flat Substrates Due to the Formation of a Randomly Oriented Nanotube Crust In this example, a description of the growth of vertically aligned single wall carbon nanotubes (or V-SWNT) on catalyst is provided. of Co-Mo supported on a flat substrate of silicon. The evolution of the growth time of V-SWNT has been examined by scanning electron microscopy (SEM) and resonant Raman spectroscopy. A different induction period has been identified, during which a thin layer or shell of two-dimensional SWNT nanotubes randomly oriented is formed on the substrate. The formation of this crust is followed by the concerted growth of a "forest" of vertical nanotubes whose height is controlled by the crust of rigid nanotubes that supports the entire structure as a whole. As a result, all SWNTs are forced to grow in a substantially aligned fashion. An X-ray study of structure near the absorption edge of angular resolution of (XANES) of the full growth SWNT forest sample was obtained. The intensity of the transitions C (ls) to pi * and C (ls) to sigma * were quantified as a function of the angle of incidence. A significant deviation of the experimental variation of intensity with incident angle from the theoretical equation that could be expected for perfectly oriented vertical nanotubes was observed at low angles of incidence. This deviation is in full agreement with the presence of a nanotube shell on an upper surface of the nanotube forest parallel to the upper surface of the substrate. further, several examples of different forms of SWNT grown on a flat substrate are given to demonstrate the effect of a nanotube shell structure on the resulting topology of the SWNT forest. (a) The Co and Mo catalyst supported on Si wafer was prepared as written in Example 1. After pretreatment, the wafer was placed in a quartz reactor, oriented parallel to the direction of the flowing gas and the growth of SWNT was carried out as described above. (b) The SWNT as produced on the catalyst / wafer (flat catalytic substrate) were characterized by Raman spectroscopy, electron microscopy (SEM and TEM), X-ray spectroscopy of structure near the edge of angular resolution (XANES). XANES spectra of CK edge of angular resolution were taken under UHV with total electron yield mode (TEY) in the bending of the magnet beam line 9.3.2 of the Advanced Light Source (ALS). English) at the Lawrence Berkely National Laboratory (LBNL). The XANES data were collected at various angles in the interval from theta = 10 ° ("oblique geometry") to theta = 80 ° ("normal geometry"), where theta denotes the angle between the normal sample and the direction of the vector electric X-ray beam. (c) Results of the XANES characterization: Figure 15 shows the changes in XANES intensities at different incident angles for the SWNT forest, where theta is also the angle between the normal sample and the vector of the electric field of the X-ray beam. The leading edge and the trailing edge in the XANES spectra were normalized to 0 and 1, respectively. Several characteristic peaks can be identified in each set of XANES spectra. The XANES spectra of CK edge of the SWNT forest are very similar to those of graphite, as have others. The spectra are characterized by an acute pC * CC transition near 284.5 eV, a sigma * acute CC link excitation near 291.5 eV, two sigma * transitions from 292 to 298 eV, and wide transitions (sigma + pi) of 301 at 309 eV. The position and width of these resonances are typical of the simple link C-C. Two small peaks in the region of 287-290 eV can be assigned to oxygenated surface functionalities introduced while processing the SWNT bosgue. This corresponds to the resonances of pi * C = 0 and sigma * C-0. Following the method proposed by Outka et al., The XANES spectra were fitted to a Gaussian series, a tangent arc stage corresponding to the excitation edge of the carbon, and a background. The presence of a local order and texture in the SWNT is observed in the angular dependency of XANES of the SWNT forest. Since the synchrotron light is horizontally linearly polarized, the intensity of the transition pi * is sensitive to the orientation of the orbital pi * with respect to the polarization vector. Therefore, if the pi * orbitals in the nanotube specimen are partially oriented with respect to the incident photon beam, a rotation of the specimen relative to the incoming photon will show a measurable angular dependence. At a normal incidence, the electric field E is in the same cross-sectional plane as the orbitals pi *, and therefore, the resonance peak pi * will be the highest at this angle, contrary to the oblique angles. In contrast, when E is normal to the surface, the field is located along the axis of the tube (along z) and is perpendicular to the plane of the orbitals pi *, the intensity of the resonance pi * is in its minimum. Specifically, there is an increase in the intensity of the resonance of pi * with the increase in the angle of incidence of the X-ray beam. The local contribution to the XAS intensity of excitation of pi * is proportional to the square of the scalar product of the normal local and E. Obviously the intensity of the resonance pi * is proportional to the square sine function of the angle of incidence. A graph of the excitation of pi * versus the angle of incidence shows a square sine dependence as shown in the lower panel of Figure 16. However, an orbital C-C sigma * orthogonal to the orbital pi * will show an opposite tendency. The pi * orbitals can be seen as the combination of two perpendicular components, one is parallel to the direction of the tube axis (sigma * //), another along the circumferential direction (also perpendicular to the axis of the tube, sigma * ± ), as seen in the upper panel of Figure 16. The local contribution to the XAS intensity of sigma excitation * at 291.5 eV is proportional to the sum of the scalar products of the two components and the electric polarization vector. With a simple calculation that considers all the contributions of sigma * in the entire circumference of the tube, we find that the intensity of the resonance of the sigma * link to 291.5 eV is proportional to (l + cos2theta). The intensity of the excitation has a square cosine dependence with respect to the angle of incidence as shown in Figure 16. It is very different from the observation of thin sheet aggregates of SWNT, whose resonance does not appear to be a systematic variation in intensity with angle of incidence due to the order of random distribution of the tubes. A marked deviation of adjusted data is observed from experimental data for both the sigma * and pi * transitions at low angles. Considering the mechanism discussed above, it is obvious to infer the presence of a crust with nanotubes oriented parallel to the substrate in the upper part of the V-SWNT. The presence of this cortex is further supported by the SEM images of Figure 17A-17B, which shows above the forest, SWNT oriented parallel to the surface in a random two-dimensional network. (d) Evolution in the Growth Time of V-SWNT In order to investigate the formation mechanism of the V-SWNT structure, we inspect the system at each stage of the growth process. The morphology of V-SWNT by SEM was observed after different reaction times. The results are summarized in the series shown in Figure 18. Starting from a flat substrate are carbon deposit, short SWNT sets evolve after 30 seconds at certain catalytically preferential points which is probably due to the geometric and compositional difference in Co-Mo particles. But at this stage, a continuous SWNT movie has not yet been formed. During the next 30 seconds almost all the particles - which are capable of nuclear caps that can grow in SWNT - have been activated. Subsequently, the SWNTs grow in this manner by raising the lids. As a result (after 60 seconds), a thin layer of randomly oriented SWNT has been woven. In 3 minutes, you can clearly see a uniform crust with sets of SWNT aligned very short below. The tangle of SWNT sets due to different growth rates and random orientation seems to stop this stage. Instead, the growth rate of each individual set is averaged by the restriction imposed by the cortex. As a result (10 min and 30 min.), Macroscopically uniform growth and alignment of the SWNTs occurs synchronously. In addition to the SEM, Raman spectroscopy was performed on the V-SWNT samples evolved over time. Figure 19 shows the Raman spectrum of V-SWNT produced in a time period of 0.5 minutes, 3 minutes and 10 minutes. The Raman characteristics include a G band at 1590 cm "1, a D band at 1340 cm" 1 and radial breathing mode at 150-300 c "1 which is typical for V-SWNT The peak at 520 cm" 1 is characteristic of the inelastic dispersion on silicon, whose intensity depends on the distance from the focal plane which is determined by the height of the V-SWNT and the area covered by the SWNT. In Figure 19, three spectra are normalized to the Si band and the amount of V-SWNT can be estimated by the size of the G band. It is clearly shown that the intensity of the G band increases with time. It's interesting, that the shape of the G bands for the cortex formed during the initial moments (0.5 min.) and for the V-SWNT formed after 10 minutes are different. As shown in the insert after normalization, the V-SWNT sample shows convergent G- and G + and a wider peak base in contrast to the acute lines and the more pronounced G- and G + separation corresponding to the cortex. The data in this example indicates that (1) the growth of a V-SWNT forest requires a very important stage (referred to as the induction period), during which a thin layer (cortex) composed of SWNT assemblies is initially formed. randomly oriented tangles as a guide surface for vertically aligned SWNT growth, and (2) after the nanotube shell is formed, the subsequent SWNT growth below is limited by the cortex, thereby causing all the nanotubes have substantially the same length. Changes may be made in the construction and operation of the various compositions, components, elements and assemblies described herein or in the steps or sequence of steps of the methods described herein without departing from the scope of the invention. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (55)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A method for forming carbon nanotubes, characterized in that it comprises: arranging a flat substrate on a movable support mechanism; apply a solution of catalytic precursors on the flat substrate forming a flat catalytic substrate; disposing the a flat catalytic substrate within a reactor; and exposing a flat catalytic substrate to a heated gas containing carbon or gasified liquid under conditions that cause the production of carbon nanotubes on a flat catalytic substrate thereby forming a flat catalytic substrate carrying carbon nanotubes.
2. 2. The method according to claim 1, characterized in that it additionally comprises the step of removing carbon nanotubes from a flat catalytic substrate carrying carbon nanotubes.
3. The method according to any of claim 1 or 2, characterized in that it includes the step of calcining and reducing a flat catalytic substrate before exposing a flat catalytic substrate to those containing carbon in the reactor.
4. 4. The method according to any of claims 1-3, characterized in that the flat substrate comprises at least one of the following: wafers and sheets of Si02, Si, Si wafers put doped with or without a layer of Si02, Si3N , Al203, MgO, quartz, oxidized silicon surfaces, silicon carbide, glass, ZnO, GaAs, GaP, GaN, Ge and InP, metal sheets such as iron, steel, stainless steel, molybdenum and ceramics including alumina, magnesia and titania
5. 5. The method according to any of claims 1-4, characterized in that the solution of catalytic precursors comprises at least one metal from the group consisting of Group VIII, Group VIb and Group Vb and rhenium metals.
6. 6. The method according to any of claims 1-5, characterized in that the movable support mechanism is a transport mechanism, plate or tape.
7. 7. The method according to any of claims 1-6, characterized in that the catalytic composition is formed on the flat substrate by spraying, coating, rotating coating, dipping or screen printing the solution of catalytic precursors thereon.
8. The method according to any of claims 1-7, characterized in that the solution of catalytic precursors is applied to the flat substrate by sputtering metal or metal evaporation.
9. 9. The method according to any of claims 1-8, characterized in that the gas or gasified liquid containing carbon is heated to a temperature of 700 ° C to 1000 ° C.
10. 10. The method according to any of claims 1-9, characterized in that the gas or liquid gasified containing carbon is selected from the group consisting of aliphatic hydrocarbons, both saturated and unsaturated, such as methane, ethane propane, butane, hexane , ethylene, and propylene; carbon monoxide; oxygenated hydrocarbons such as ketones, aldehydes, and alcohols including ethanol and methanol; aromatic hydrocarbons such as toluene, benzene and naphthalene; and mixtures of the above.
11. The method according to any of claims 1-10, characterized in that the carbon-containing gas can optionally be mixed with a diluent gas such as helium, argon or hydrogen or a gasified liquid such as steam.
12. 12. The method according to any of claims 1-11, characterized in that the carbon nanotubes produced on the flat catalytic substrate are mainly single-walled carbon nanotubes.
13. 13. The method according to any of claims 1-12, characterized in that the carbon nanotubes produced on the flat catalytic substrate are oriented mainly vertically.
14. 14. The method according to any of claims 1-12, characterized in that the carbon nanotubes produced on the flat catalytic substrate are mainly oriented horizontally.
15. 15. The method according to any of claims 1-14, characterized in that in the step of removing the carbon nanotubes, the carbon nanotubes are cut from the flat catalytic substrate with a blade or other cutting device.
16. 16. The method according to any of claims 1-15, characterized in that the step of removing the carbon nanotubes includes the use of a gaseous or liquid medium in configurations which include passing the tape through a tangue and using sonication to promote the release of the tubes or to subject the nanotubes to a cutting field such as gas or liquid.
17. 17. The method according to any of claims 1-16, characterized in that the step of removing the carbon nanotubes includes contacting the flat catalytic substrate carrying carbon nanotubes is a sticky material.
18. 18. The method according to any of claims 1-17, characterized in that the flat catalytic substrate is removed from the movable support mechanism after use.
19. 19. The method according to any of claims 1-17, characterized in that the flat catalytic surface is retained on the movable support mechanism for more than one use.
20. 20. The method according to any of claims 1-19, characterized in that the solution of catalytic precursors is applied to the flat substrate before it is placed on the movable support system.
21. 21. A method of forming carbon nanotubes on a flat substrate, characterized in that it comprises: providing a flat substrate; providing a solution of catalytic precursors for preparing the catalyst composition, the catalyst precursor solution comprising a catalytic metal, a surface wetting agent, and a catalyst stabilizer; apply the solution of catalytic precursors on the flat substrate and dry the solution of catalytic precursors forming the catalytic composition on it forming a flat catalytic substrate; and exposing the flat catalytic substrate to a gas or heated gasified liquid containing carbon causing the production of carbon nanotubes on the flat catalytic substrate forming a flat catalytic substrate that carries carbon nanotubes.
22. 22. The method according to claim 21, characterized in that the carbon nanotubes are mainly single-walled carbon nanotubes.
23. 23. The method according to any of claims 21 or 22, characterized in that the carbon nanotubes are mainly vertically oriented carbon nanotubes.
24. 24. The method according to any of claims 21 or 22, characterized in that the carbon nanotubes are mainly horizontally oriented carbon nanotubes.
25. 25. The method according to any of claims 21-24, characterized in that the surface humidifying agent of the catalytic metal composition is selected from the group consisting of silicates, silanes, and organosilanes, including polysiloxanes, polycarbosilanes, organosilazanes, polysilazanes , siloxanes derived from alkoxides, alkyl-cyclosiloxanes, alkyl-alkoxy silanes, poly-alkyl-siloxanes, amino-alkyl-alkoxy-silanes, and alkyl-orthosilicates.
26. 26. The method according to any of claims 21-25, characterized in that the catalyst stabilizer of the catalytic metal composition is selected from the group consisting of: silicates, silanes, and organosilanes including polysiloxanes, polycarbosilanes, organosilazanes, polysilazanes, siloxanes derivatives of alkoxides, alkyl-cyclosiloxanes, alkyl-alkoxy silanes, poly-alkyl-siloxanes, amino-alkyl-alkoxy-silanes, or alkyl-orthosilicates, as well as organotitanates, such as titanium alkoxides or titanoxanes; organic aluminoxy compounds, organozirconates, and organomagnesium compounds (including Mg alkoxide).
27. 27. The method according to any of claims 21-26, characterized in that the humidifying agent and the catalyst stabilizer are the same.
28. 28. The method according to any of claims 21-27, characterized in that the catalytic metal of the catalytic metal composition comprises at least one metal selected from the group consisting of Group VIII metals, Group VIb metals and Group metals. Vb and rhenium.
29. 29. The method according to any of claims 21-28, characterized in that the catalytic metal comprises at least one Group VIII metal and at least one Group VIb metal.
30. The method according to any of claims 21-29, characterized in that the catalytic metal is Co and Mo.
31. 31. The method according to any of claims 21-30, characterized in that before the formation of carbon nanotubes. vertically oriented from the upper surface, a horizontal layer of carbon nanotubes is formed randomly oriented on the surface forming a superior crust on the carbon nanotubes oriented vertically as the carbon nanotubes are formed vertically oriented between the upper surface and the horizontal layer of carbon nanotubes. carbon nanotubes randomly oriented.
32. 32. The method according to any of claims 21-23 and 25-31, characterized in that the single-walled carbon nanotubes comprise from 60% to 90% of the vertically oriented carbon nanotubes.
33. 33. The method according to any of claims 21-32, characterized by comprising the additional step of removing the vertically oriented carbon nanotubes from the flat catalytic substrate which carries carbon nanotubes.
34. 34. The method according to any of claims 21-33, characterized in that the carbon nanotubes are removed by cutting by means of a blade, sonication, cutting via the application of a gas or liquid cutting field, or the application of a film, adhesive material, or other sticky material to which carbon nanotubes can adhere or trap.
35. 35. The method according to any of claims 21-34, characterized in that the catalytic metal composition is applied to the flat substrate by spraying, dripping, coating, rotating coating, dipping, or screen printing.
36. 36. The method according to any of claims 21-35, characterized in that when the solution of the dry catalyst composition on the flat substrate is formed atalitic islands on it, and where the catalytic islands are separated by an average distance of 30 nm to 100 nm.
37. 37. The method according to any of claims 21-36, characterized in that the catalytic composition on the flat substrate comprises metallic species which remain at least partially mixed with a decomposition product of the catalyst stabilizer or humidifying agent.
38. 38. The method according to any of claims 21-37, characterized in that the flat substrate comprises at least one of the following: wafers and sheets of SiO2, Si, wafers of Si p or n doped with or without a layer of Si02, Si3N4, Al203, MgO, quartz, oxidized silicon surfaces, silicon carbide, glass, ZnO, GaAs, GaP, GaN, Ge and InP, metal sheets such as iron, steel, stainless steel, and molybdenum and ceramics including alumina , magnesia and titania.
39. 39. The method according to any of claims 21-38, characterized in that the gas or liquid gasified containing carbon is selected from the group consisting of aliphatic hydrocarbons, both saturated and unsaturated, such as methane, ethane propane, butane, hexane , ethylene, and propylene; carbon monoxide; oxygenated hydrocarbons such as ketones, aldehydes, and alcohols including ethanol and methanol; aromatic hydrocarbons such as toluene, benzene and naphthalene; and mixtures of the above.
40. 40. The method according to any of claims 21-39, characterized in that the carbon-containing gas can be mixed with a diluent gas such as helium, argon or hydrogen or a gasified liquid such as water vapor.
41. 41. A method of transferring carbon nanotubes from a catalytic substrate, characterized in that it comprises: providing a catalytic substrate having a flat surface, the catalytic substrate has carbon nanotubes on the flat surface thereof; applying a transfer medium to the layer of carbon nanotubes, wherein the transfer medium can adhere or trap carbon nanotubes in such a way that the carbon nanotubes adhere or are embedded in the transfer medium; and removing the transfer medium from the catalytic surface thereby substantially completely removing the carbon nanotubes from the catalytic substrate.
42. 42. The method according to claim 41, characterized in that the transfer medium comprises polymeric material, an elastomeric material, a metal, a ceramic, such as quartz, alumina, silicates, carbides, and nitrides, disordered films comprising inorganic oxides such as silica, or polymers, and carbon.
43. 43. The method according to any of claims 41 or 42, characterized in that the catalytic substrate comprises at least one of the following: wafers and sheets of SiO2, Si, Si wafers put doped with or without a layer of SiO2, Si3N4 , Al203, MgO, quartz, oxidized silicon surfaces, silicon carbide, glass, ZnO, GaAs, GaP, GaN, Ge and InP, metal sheets such as iron, steel, stainless steel, and molybdenum and ceramics including alumina, magnesia and titania.
44. 44. The method according to any of claims 41-43, characterized in that the transfer medium comprises a polymeric material which is applied as a liquid or semi-solid to the layer of carbon nanotubes.
45. 45. The method according to any of claims 41-44, characterized in that the carbon nanotubes are transferred by the application of a liquid film on the carbon nanotubes, reducing the temperature in order to freeze the liquid, and remove mechanically frozen liquid and carbon nanotubes.
46. 46. The method according to any of claims 41-45, characterized in that the polymeric material comprises polypropylene, polyethylene, polyacrylamide, polycarbonate, polyethylene terephthalate (PET), polyvinyl chloride, polystyrene, polyurethane, Teflon, Saran, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate (PMMA), polyacrylates, poligro rubber, polyesters , and polyamides such as nylon, as well as polymers formed in situ for example by crosslinking prepolymers.
47. 47. The method according to any of claims 41-46, characterized in that the transfer medium is a polymer film having a layer of adhesive thereon.
48. 48. The method according to any of claims 41-43, characterized in that the transfer medium is a metal.
49. 49. The method according to any of claims 41-48, characterized in that the carbon nanotubes are embedded substantially completely in the transfer medium.
50. 50. The method according to any of claims 41-48, characterized in that the carbon nanotubes are only partially embedded in the transfer medium in such a way that the carbon nanotubes are exposed at least partially.
51. 51. A carbon nanotube structure, characterized by porgue comprises: a flat catalytic substrate having a catalytic surface; a first layer of carbon nanotubes comprising randomly oriented carbon nanotubes; and a second layer of carbon nanotubes comprising vertically oriented carbon nanotubes, and wherein the first layer of nanotubes is arranged as an outer shell on the second layer of nanotubes in such a way that the second layer of nanotubes is located between the first layer of nanotubes. layer of nanotubes and the catalytic surface of the flat substrate.
52. 52. The carbon nanotube structure according to claim 51, characterized in that the carbon nanotubes are mainly single-walled carbon nanotubes.
53. 53. The structure of carbon nanotubes according to any of claims 51-52, characterized in that the flat substrate is constructed of a material comprising wafers and sheets of SiO2, Si, Si wafers or doped with or without a layer of Si02, Si3N4, Al203, MgO, quartz, glass, oxidized silicon surfaces, silicon carbide, ZnO, GaAs, GaP, GaN, Ge and InP, metal sheets such as iron, steel, stainless steel, and molybdenum and ceramics such as alumina, magnesia and titania.
54. 54. The carbon nanotube structure according to any of claims 51-53, characterized in that the catalytic surface comprises catalytic islands thereon comprising one or more metals selected from the group consisting of Group VIII metals, Group VIb metals , Group Vb metals and Re.
55. 55. The structure of carbon nanotubes according to any of claims 51-54, characterized in that the catalytic islands are formed on the catalytic surface, and wherein the catalytic islands are separated by a distance average of 30 nm to 100 nm.