Carbon nanotube hybrid materials

Abstract

A method for catalytically growing carbon nanotubes on a carbonaceous substrate, and hybrid materials prepared by the method.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Indian Patent Application No. 202211060980, filed October 26, 2022, and U.S. Provisional Application No. 63 / 431,368, filed December 9, 2022, both of which are incorporated herein by reference. [Background technology]

[0002] Carbon black is a form of amorphous carbon used as a pigment or reinforcing filler in rubber and plastic products. Due to its graphitic crystallinity, it imparts some electrostatic properties to non-conductive materials, and therefore finds applications in many areas, such as conductive polymers, inks, paints, and antistatic coatings. In some applications, other forms of nanostructured carbon, such as carbon nanotubes (CNTs), can be combined with carbon black to improve the electrical conductivity, mechanical properties, and chemical strength of the final product.

[0003] CNTs are one-atom-thick carbon sheets rolled to form cylinders with diameters in the nanometer range and lengths up to a few microns. CNTs can be used in composites and microelectronics due to their excellent chemical, mechanical, thermal, and optical properties. However, due to cost, it can be desirable to optimize CNT loading to maintain a material balance between performance and cost. The performance of CNT composites generally depends on a homogeneous mixture of different nanostructures within the vehicle matrix.

[0004] Existing physical mixing methods often result in inhomogeneous dispersions, which have only a minor effect on the final properties. Additionally, mixing two nanoscale components in a vehicle matrix can pose safety hazards during handling. To achieve a single, cohesive material, incorporating CNTs onto the surface of a carbon structure may be beneficial. Summary of the Invention

[0005] The present disclosure describes an improved method for growing CNTs on catalyzed carbonaceous substrates using various feed gases. The creation of the disclosed composite material involves producing catalyzed carbon as a support for growing CNTs on the support. The method utilizes a green approach by utilizing biosources, such as lignin or suitable water-soluble lignin derivatives, to synthesize catalyzed carbon without the use of organic solvents. In contrast, many existing wet impregnation methods often require harsh acidic conditions, expensive surfactants, or multi-step processing to uniformly disperse the catalyst on the carbon support. Unlike the disclosed method, existing methods are expensive or cumbersome.

[0006] In one aspect, a method for making a carbon nanotube hybrid material includes: (a) dispersing a carbonaceous substrate in a medium comprising water and one or more of the following: (i) lignin and a first base or (ii) a water-soluble lignin derivative, wherein the medium is free of organic solvents and non-lignin-derived surfactants; (b) contacting the medium with a metal salt and a second base; (c) forming catalytic sites on the carbonaceous substrate from the metal salt to provide a catalyzed carbonaceous substrate; and (d) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate.

[0007] In a further aspect, the method includes: (a) dispersing a carbonaceous substrate in a medium comprising water and one or more of the following: (i) lignin and a first base or (ii) a water-soluble lignin derivative; (b) contacting the medium with a metal salt and a second base; (c) obtaining a solid from the medium, the solid comprising the carbonaceous substrate and the metal salt supported on the carbonaceous substrate; (d) calcining the solid to convert the metal salt to a metal oxide; (e) reducing the metal oxide to its corresponding elemental metal to form a catalyzed carbonaceous substrate; and (f) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate.

[0008] Carbon nanotube hybrid materials made by any of the disclosed methods are also described. [Brief explanation of the drawings]

[0009] The foregoing summary, as well as the following description of the present disclosure, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the present disclosure, the drawings illustrate some, but not all, alternative embodiments. The disclosure is not limited to the precise arrangements and instrumentalities shown. The following figures, which are incorporated in and constitute a part of this specification, help to explain the principles of the present disclosure.

[0010] [Figure 1A-C] SEM images of hybrid materials made from nickel catalysts deposited on Raven PFEB (Birla Carbon, Marietta, GA, USA) using carbon monoxide (CO, H, N) as the feed gas are shown in Figure 1A (500 nm scale, Figure 1B: 2 μm scale, Figure 1C: 10 μm scale). [Figure 2] 16 is a Raman spectrum of a hybrid material made from a nickel catalyst deposited on a Raven PFEB substrate with a corresponding Id / Ig ratio of 1.01. [Figure 3A-C] SEM images of exemplary hybrid materials made from a nickel catalyst deposited on a Raven PFEB, a hybrid material made from nickel and cobalt catalysts deposited on a Raven PFEB, and a hybrid material made from a cobalt molybdenum catalyst deposited on a Raven PFEB are shown along with magnified HRTEM insets showing the carbon nanotube morphology (Figure 3A: 2 μm scale, Figure 3B: 5 μm scale, Figure 3C: 2 μm scale). [Figure 4] Figure 4 shows an HRTEM image of a hybrid material made from nickel catalyst deposited on Raven PFEB using ethylene (ethylene, H2, and N2) as the feed gas (Example 2) (10 nm scale). [Figure 5]Figure 5 shows an SEM image of a hybrid material made from a Ni catalyst deposited on graphite using carbon monoxide (CO, H, and N) as the feed gas (Example 3) (10 μm scale). [Figure 6] TEM images of carbon-CNT hybrid materials prepared on Ni-supported Raven PFEB using water-soluble derivatives of lignin and ethylene (ethylene, H, and N) as feed gases (Example 4) (FIG. 6, 20 nm scale). DETAILED DESCRIPTION OF THE INVENTION

[0011] One aspect of the method includes: (a) dispersing a carbonaceous substrate in a medium comprising water and one or more of the following: (i) lignin and a first base or (ii) a water-soluble lignin derivative; (b) contacting the medium with a metal salt and a second base; (c) forming catalytic sites on the carbonaceous substrate from the metal salt to provide a catalyzed carbonaceous substrate; and (d) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate.

[0012] One advantage of the present method is that the medium may be free of organic solvents and non-lignin-derived surfactants. Generally, organic solvents are not required because the present process involves water-soluble metal salts. Specific examples of unnecessary organic solvents include alcohols, such as ethanol, propanol, isopropyl alcohol, and the like, as well as any other volatile organic solvents, such as dichloromethane, chloroform, and others known to those skilled in the art. In some aspects, the present method does not involve the use of organic solvents as a whole, i.e., organic solvents are not used in any step of the process.

[0013] Another advantage of the present method is that it avoids the use of non-lignin-derived surfactants, making it environmentally friendly and sustainable. For example, the medium may be free of non-lignin-derived nonionic surfactants, non-lignin-derived zwitterionic surfactants, non-lignin-derived cationic or amphoteric surfactants. In a particular example, the medium may be free of Triton surfactants, including Triton-X-100.

[0014] The method is suitable for a variety of carbonaceous substrates. Examples include natural graphite, synthetic graphite, graphene, carbon black, carbon fiber, or activated carbon. In one embodiment, the carbonaceous substrate is carbon black. A specific example is Raven PFEB carbon black (Birla Carbon, Marietta, GA, USA). In another embodiment, the carbonaceous substrate is graphite.

[0015] Generally, the first base can be any base suitable for providing a medium pH in the range of 8 to 12. Suitable first bases include ammonia, carbonate, bicarbonate, or hydroxide bases. Specific examples include sodium hydroxide, ammonium bicarbonate, and potassium hydroxide.

[0016] When using a water-soluble lignin derivative, such as an anionic lignin derivative, a first base is not required to dissolve the lignin derivative in the medium. Examples of suitable anionic lignin derivatives include lignosulfonates, which are generally water-soluble anionic polyelectrolyte polymers and are by-products of wood pulp production using sulfite pulping. With water-soluble lignin derivatives, a first base is not required to dissolve the derivative in the aqueous medium, but a second base may be useful for precipitating the metal salt and supporting the metal salt on the carbonaceous substrate. A combination of lignin, a first base, and a water-soluble lignin derivative can also be used.

[0017] The second base and any first base may be the same or different. Suitable examples of the second base include ammonia, carbonate, bicarbonate, or hydroxide bases. Specific examples include sodium hydroxide, ammonium bicarbonate, and potassium hydroxide. In one aspect, the first base, when used with lignin, can be a hydroxide base such as sodium hydroxide or potassium hydroxide, and the second base used in the metal salt loading step can be an ammonia base such as ammonium bicarbonate.

[0018] Various metal salts can be used as precursors to metal oxides that can be formed when the carbonaceous substrate is calcined after loading with the metal salt. In one embodiment, the metal salt is a d-block transition metal salt. In a further embodiment, the metal salt is iron-based. In another embodiment, the metal salt is non-ferrous. In a further embodiment, the metal salt is a salt of iron, nickel, molybdenum, copper, or cobalt. Any metal salt with a suitable anion is contemplated. In one embodiment, the metal salt is a transition metal nitrate, transition metal acetate, transition metal citrate, transition metal chloride, or any hydrate or combination of these salts.

[0019] In one aspect, forming catalytic sites on a carbonaceous substrate from a metal salt comprises converting the metal salt to a metal oxide, followed by reducing the metal oxide to its corresponding elemental metal. Thus, the term "catalyzed carbonaceous substrate" refers to a carbonaceous substrate that has a catalyst formed or deposited on it.

[0020] In one particular embodiment, the method includes: (a) dispersing a carbonaceous substrate in a medium comprising water and one or more of the following: (i) lignin and a first base or (ii) a water-soluble lignin derivative; (b) contacting the medium with a metal salt and a second base; (c) obtaining a solid from the medium, the solid comprising the carbonaceous substrate and the metal salt supported on the carbonaceous substrate; (d) calcining the solid to convert the metal salt to a metal oxide; (e) reducing the metal oxide to its corresponding elemental metal to form a catalyzed carbonaceous substrate; and (f) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate. The dispersion may be free of organic solvents, free of non-lignin-derived surfactants, or both, as described above.

[0021] In one embodiment, calcination can be carried out at a temperature ranging from 400°C to 650°C. "Calining" refers to the thermal treatment of a solid by raising the solid to a high temperature without melting it to convert metal salts to metal oxides. In a further embodiment, the solid can be obtained by filtering the solid from the medium, washing the solid, and drying the solid at a temperature below 100°C prior to calcination, followed by the calcination step. In a further embodiment, the metal oxide can be reduced to its corresponding elemental metal using hydrogen gas. In a further embodiment, the catalyzed carbonaceous substrate can be exposed to a carbon-containing gas at a temperature ranging from 600°C to 1200°C, e.g., 600°C to 1000°C, 600°C to 800°C, or in one particular embodiment, about 700°C. Generally, the disclosed process can be carried out using any suitable reactor, such as a fluidized bed reactor, a rotary reactor, or a tubular reactor.

[0022] Various carbon-containing gases and mixtures thereof are contemplated. Carbon-containing gases may include, for example, carbon monoxide, ethylene, acetylene, methane, benzene, xylene, carbon dioxide, or combinations thereof. Other composite gases may be used with any carbon-containing gas, such as hydrogen, nitrogen, etc. One non-limiting example of a carbon-containing gas is ethylene, hydrogen, and nitrogen, which may be used, for example, in a 10:10:80 volume % ratio (ethylene:H2:N2). Another example of a carbon-containing gas is carbon monoxide, hydrogen, and nitrogen, which may be used, for example, in a 40:40:20 volume % ratio (CO:H2:N2).

[0023] In some embodiments, the percent yield of carbon nanotubes formed on the carbonaceous substrate can range from about 100 to 500% by weight of the carbonaceous substrate.

[0024] Carbon nanotube hybrid materials made by any embodiment of the disclosed methods are also described.

[0025] A further advantage of the described methods is that, in some embodiments, the methods do not require the use of non-catalytic materials at any step of the process, including, for example, during steps involving carbon nanotube growth. It has been found that the described methods can enable thin, uniform growth of carbon nanotubes on a carbonaceous substrate without the need to deposit non-catalytic materials on the carbonaceous substrate in addition to metal oxides that are ultimately reduced to the corresponding metals to form the catalyzed carbonaceous substrate. In other words, it has been observed that any interaction between the catalytic sites and the carbonaceous substrate itself does not interfere with carbon nanotube growth. Specific non-catalytic materials that can be excluded from the process include aluminum, aluminum salts, hydrates of aluminum salts, glass, silicates, silanes, and the like.

[0026] Similarly, the disclosed methods do not require a polymer coating on the carbonaceous substrate prior to the formation of carbon nanotubes on the substrate, e.g., no barrier coating of a polymer of furfuryl alcohol is required on the carbonaceous substrate.

[0027] Exemplary Embodiments Without limitation, the following exemplary aspects of the present disclosure are specifically contemplated.

[0028] Aspect (1): A method for making a carbon nanotube hybrid material, the method comprising: (a) dispersing a carbonaceous substrate in a medium comprising water and one or more of the following: (i) lignin and a first base or (ii) a water-soluble lignin derivative, wherein the medium is free of organic solvents and non-lignin-derived surfactants; (b) contacting the medium with a metal salt and a second base; (c) forming catalytic sites on the carbonaceous substrate from the metal salt to provide a catalyzed carbonaceous substrate; and (d) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate.

[0029] Aspect (2): The method of aspect (1), wherein the carbonaceous substrate comprises natural graphite, synthetic graphite, graphene, carbon black, carbon fiber, or activated carbon.

[0030] Embodiment (3): The method of any of the preceding embodiments, wherein the first base brings the medium pH to a range of 8 to 12.

[0031] Embodiment (4): The method of any preceding embodiment, wherein the first base is an ammonia, carbonate, bicarbonate, or hydroxide base.

[0032] Embodiment (5): The method of any preceding embodiment, wherein the first base is sodium hydroxide.

[0033] Embodiment (6): The method of any preceding embodiment, wherein the second base is an ammonia, carbonate, bicarbonate, or hydroxide base.

[0034] Embodiment (7): The method of any preceding embodiment, wherein the second base is sodium hydroxide.

[0035] Embodiment (8): The method of any preceding embodiment, wherein the second base is ammonium bicarbonate.

[0036] Aspect (9): The method of any of the preceding aspects, wherein the water-soluble lignin derivative is an anionic lignin derivative.

[0037] Aspect (10): The method of any of the preceding aspects, wherein the water-soluble lignin derivative is a lignosulfonate.

[0038] Embodiment (11): The method of any preceding embodiment, wherein the metal salt is a d-block transition metal salt.

[0039] Aspect (12): The method of any of the preceding aspects, wherein the metal salt is ferrous or non-ferrous.

[0040] Embodiment (13): The method of any of the preceding embodiments, wherein the metal salt is a salt of iron, nickel, molybdenum, or cobalt, or a combination thereof.

[0041] Embodiment (14): The method of any preceding embodiment, wherein forming catalytic sites on the carbonaceous substrate from a metal salt comprises converting the metal salt to a metal oxide, and subsequently reducing the metal oxide to its corresponding elemental metal.

[0042] Aspect (15): The method of any of the preceding aspects, wherein the carbon-containing gas comprises ethylene, acetylene, methane, benzene, xylene, carbon dioxide, or a combination thereof.

[0043] Aspect (16): A carbon nanotube hybrid material produced by the method of any of the preceding aspects.

[0044] Aspect (17): A method for making a carbon nanotube hybrid material, the method comprising: (a) dispersing a carbonaceous substrate in a medium comprising water and one or more of: (i) lignin and a first base or (ii) a water-soluble lignin derivative; (b) contacting the medium with a metal salt and a second base; (c) obtaining a solid from the medium, the solid comprising the carbonaceous substrate and the metal salt supported on the carbonaceous substrate; (d) calcining the solid to convert the metal salt to a metal oxide; (e) reducing the metal oxide to its corresponding elemental metal to form a catalyzed carbonaceous substrate; and (f) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate.

[0045] Aspect (18): The method of aspect (17), wherein the dispersion does not include an organic solvent.

[0046] Aspect (19): The method of aspect (17) or (18), wherein the dispersion does not contain a non-lignin-derived surfactant.

[0047] Aspect (20): The method of any one of Aspects (17) to (19), wherein the carbonaceous substrate comprises natural graphite, synthetic graphite, graphene, carbon black, carbon fiber, or activated carbon.

[0048] Aspect (21): The method according to any one of Aspects (17) to (20), wherein the first base adjusts the medium pH to a range of 8 to 12.

[0049] Aspect (22): The method of any one of Aspects (17) to (21), wherein the first base is an ammonia, carbonate, bicarbonate, or hydroxide base.

[0050] Aspect (23): The method of any one of Aspects (17) to (22), wherein the first base is sodium hydroxide.

[0051] Aspect (24): The method of any one of Aspects (17) to (23), wherein the second base is an ammonia, carbonate, bicarbonate, or hydroxide base.

[0052] Aspect (25): The method of any one of Aspects (17) to (24), wherein the second base is sodium hydroxide.

[0053] Aspect (26): The method of any one of Aspects (17) to (25), wherein the second base is ammonium bicarbonate.

[0054] Aspect (27): The method according to any one of Aspects (17) to (26), wherein the water-soluble lignin derivative is an anionic lignin derivative.

[0055] Aspect (28): The method according to any one of Aspects (17) to (27), wherein the water-soluble lignin derivative is a lignosulfonate.

[0056] Aspect (29): The method of any one of Aspects (17) to (28), wherein the metal salt is a d-block transition metal salt.

[0057] Aspect (30): The method of any one of Aspects (17) to (29), wherein the metal salt is non-ferrous.

[0058] Aspect (31): The method of any one of Aspects (17) to (30), wherein the metal salt is a salt of nickel, molybdenum, or cobalt, or a combination thereof.

[0059] Aspect (32): The method according to any one of Aspects (17) to (31), wherein the calcination is carried out at a temperature in the range of 400°C to 650°C.

[0060] Aspect (33): The method of any one of Aspects (17) to (32), wherein the solid is obtained by filtering the solid from the medium, washing the solid, and drying the solid at a temperature less than 100°C.

[0061] Embodiment (34): The method of any one of embodiments (17) to (33), wherein the metal oxide is reduced to its corresponding elemental metal using hydrogen gas.

[0062] Embodiment (35): The method of any one of Embodiments (17) to (34), wherein the catalyzed carbonaceous substrate is exposed to a carbon-containing gas at a temperature in the range of 600°C to 1200°C.

[0063] Aspect (36): The method of any one of Aspects (17) to (35), wherein the carbon-containing gas comprises ethylene, acetylene, methane, benzene, xylene, carbon dioxide, or a combination thereof.

[0064] Aspect (37): A carbon nanotube hybrid material produced by the method of any of the preceding aspects. [Example]

[0065] The present disclosure is further illustrated by the following examples, which do not limit the scope of the present disclosure and claims.

[0066] Example 1 An exemplary carbon nanotube hybrid material was prepared according to the following method. Lignin was dissolved in an alkaline aqueous medium (0.0032 M NaOH, i.e., the first base), and carbon black was added. The mixture was stirred to disperse the carbon black in the medium. Nickel metal salt (Ni(NO3)2) was added dropwise along with an alkaline source, in this case NH4HCO3, i.e., the second base. The resulting mixture was stirred at 80°C for 3 hours. The solid carbon black substrate with Ni metal salt loaded on the substrate was then filtered from the aqueous medium and washed to remove impurities, including residual lignin and lignin derivatives. The solid was dried at 80°C for 12 hours under vacuum or 24 hours under vacuum at 80°C.

[0067] To prepare the catalyzed substrate, the dried solid was calcined at 600 °C for 4 hours under a nitrogen atmosphere. The resulting catalyzed substrate was then heated under a nitrogen atmosphere. Once the furnace temperature reached 700 °C, carbon monoxide and hydrogen gases were passed through the furnace while the furnace temperature was maintained between 680 °C and 1200 °C for a period of 10 minutes to 3 hours. The heating was turned off, the substrate was cooled under a nitrogen atmosphere, and the resulting carbon nanotube-carbon black hybrid substrate was collected. The yield of CNT formation was found to be 264 wt% of the carbonaceous substrate.

[0068] The specific carbon black substrate used was Raven PFEB (Birla Carbon, Marietta, GA, USA). The nickel catalyst loading on the substrate was confirmed to be 18.24 wt% of the substrate. SEM images of the hybrid material are shown in Figure 1A-C (A: 500 nm scale, B: 2 μm scale, C: 10 μm scale), demonstrating that uniform, thin carbon nanotubes were grown on the carbon black, which appear as grape-like clusters in the SEM images. The Raman spectrum of the hybrid material is shown in Figure 2.

[0069] Additional metal catalysts were also evaluated, and the yields are shown in Table 1. The corresponding SEM / HRTEM images of the Ni-Raven PFEB hybrid, Ni-Co / Raven PFEB hybrid, and Co-Mo / Raven PFEB hybrid are shown in Figures 3A (2 μm scale), 3B (5 μm scale), and 3C (2 μm scale), respectively. [Table 1]

[0070] Example 2 In this example, ethylene was used as the carbon source. The catalyzed substrate prepared as described above was heated under a nitrogen atmosphere. Once the furnace temperature reached 700 °C, ethylene, hydrogen, and nitrogen gas (10:10:80 vol%) were passed through the furnace while maintaining the furnace temperature at 700 °C for a period of 30 minutes to 3 hours. The heating was turned off, the substrate was cooled under a nitrogen atmosphere, and the resulting carbon nanotube-carbon black hybrid substrate was collected. The yield of the carbonaceous material was found to be in the range of 300-500%. The resulting TEM image is shown in Figure 4.

[0071] Example 3 In this example, graphite was used as the catalyst support. Ni was deposited on the graphite support using a lignin co-precipitation process in a manner similar to that previously described. The catalyzed substrate was heated under a nitrogen atmosphere. Once the furnace temperature reached 700 °C, carbon monoxide, hydrogen, and nitrogen gas (40:40:20 vol%) were passed through the furnace while the furnace temperature was maintained at 700 °C for a period of 3 hours. The heating was turned off, the substrate was cooled under a nitrogen atmosphere, and the resulting carbon nanotube-carbon black hybrid substrate was collected. The percent yield of the carbonaceous material was found to be in the range of 300-500%. The resulting SEM images are shown in Figure 5.

[0072] Example 4 In this example, a water-soluble lignin derivative was used to disperse carbon black, Raven PFEB, in an aqueous medium. Catalyst deposition was performed in a similar manner to that described in the previous example. The catalyzed substrate was heated under a nitrogen atmosphere. Once the furnace temperature reached 700°C, ethylene, hydrogen, and nitrogen gas (10:10:80% by volume) were passed through the furnace while the furnace temperature was maintained at 700°C for 3 hours. The heating was turned off, the substrate was cooled under a nitrogen atmosphere, and the resulting carbon nanotube-carbon black hybrid substrate was collected. The percent yield of carbonaceous material was found to be in the range of 100-200%. The resulting TEM image is shown in Figure 6.

[0073] The features and advantages of the present disclosure are apparent from the detailed specification, and the claims encompass all such features and advantages. Many variations will occur to those skilled in the art, and any variations equivalent to those described in this disclosure are within the scope of the present disclosure. Those skilled in the art will appreciate that the conception on which the present disclosure is based may be used as a basis for designing other methods and systems for carrying out some of the purposes of the present disclosure. Consequently, the claims should not be deemed limited by the descriptions or examples.

Claims

1. 1. A method for making a carbon nanotube hybrid material, comprising: a) water and: i) lignin and a first base, or ii) a water-soluble lignin derivative, Dispersing a carbonaceous substrate in a medium that is free of organic solvents and non-lignin-derived surfactants; b) contacting the medium with a metal salt and a second base; c) forming catalytic sites on the carbonaceous substrate from the metal salt to provide a catalyzed carbonaceous substrate; and d) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate.

2. 10. The method of claim 1, wherein the carbonaceous substrate comprises natural graphite, synthetic graphite, graphene, carbon black, carbon fiber, or activated carbon.

3. 2. The method of claim 1, wherein the first base provides a medium pH in the range of 8 to 12.

4. 10. The method of claim 1, wherein the first base is an ammonia, carbonate, bicarbonate, or hydroxide base.

5. 10. The method of claim 1, wherein the first base is sodium hydroxide.

6. 10. The method of claim 1, wherein the second base is an ammonia, carbonate, bicarbonate, or hydroxide base.

7. 10. The method of claim 1, wherein the second base is sodium hydroxide.

8. 10. The method of claim 1, wherein the second base is ammonium bicarbonate.

9. The method of claim 1 , wherein the water-soluble lignin derivative is an anionic lignin derivative.

10. The method of claim 1 , wherein the water-soluble lignin derivative is a lignosulfonate.

11. The method of claim 1 , wherein the metal salt is a d-block transition metal salt.

12. The method of claim 1 , wherein the metal salt is ferrous or non-ferrous.

13. 10. The method of claim 1, wherein the metal salt is an iron, nickel, molybdenum, or cobalt salt, or a combination thereof.

14. 10. The method of claim 1, wherein forming catalytic sites on the carbonaceous substrate from the metal salt comprises converting the metal salt to a metal oxide, followed by reducing the metal oxide to its corresponding elemental metal.

15. The method of claim 1 , wherein the carbon-containing gas comprises ethylene, acetylene, methane, benzene, xylene, carbon dioxide, or a combination thereof.

16. A carbon nanotube hybrid material produced by the method of any one of claims 1 to 15.

17. 1. A method for making a carbon nanotube hybrid material, comprising: a) water and: i) lignin and a first base, or ii) a water-soluble lignin derivative; and b) contacting the medium with a metal salt and a second base; c) obtaining a solid from the medium, the solid comprising the carbon substrate agent having the metal salt supported thereon; d) calcining the solid to convert the metal salt to a metal oxide; e) reducing the metal oxide to its corresponding elemental metal to form a catalyzed carbonaceous substrate; f) exposing the catalyzed carbonaceous substrate to a carbon-containing gas to grow carbon nanotubes on the catalyzed carbonaceous substrate.

18. 18. The method of claim 17, wherein the dispersion is free of organic solvents.

19. 19. The method of claim 17 or 18, wherein the dispersion is free of non-lignin derived surfactants.

20. 18. The method of claim 17, wherein the carbonaceous substrate comprises natural graphite, synthetic graphite, graphene, carbon black, carbon fiber, or activated carbon.

21. 18. The method of claim 17, wherein the first base provides a medium pH in the range of 8 to 12.

22. 18. The method of claim 17, wherein the first base is an ammonia, carbonate, bicarbonate, hydroxide base.

23. 18. The method of claim 17, wherein the first base is sodium hydroxide.

24. 18. The method of claim 17, wherein the second base is an ammonia, carbonate, bicarbonate, or hydroxide base.

25. 18. The method of claim 17, wherein the second base is sodium hydroxide.

26. 18. The method of claim 17, wherein the second base is ammonium bicarbonate.

27. 18. The method of claim 17, wherein the water-soluble lignin derivative is an anionic lignin derivative.

28. 18. The method of claim 17, wherein the water-soluble lignin derivative is a lignosulfonate.

29. 18. The method of claim 17, wherein the metal salt is a d-block transition metal salt.

30. 18. The method of claim 17, wherein the metal salt is non-ferrous.

31. 18. The method of claim 17, wherein the metal salt is a salt of nickel, molybdenum, or cobalt, or a combination thereof.

32. 18. The method of claim 17, wherein the calcining is carried out at a temperature in the range of 400°C to 650°C.

33. 18. The method of claim 17, wherein the solids are obtained from the medium by filtering the solids from the medium, washing the solids, and drying the solids at a temperature less than 100°C.

34. 18. The method of claim 17, wherein the metal oxide is reduced to its corresponding elemental metal using hydrogen gas.

35. 18. The method of claim 17, wherein the catalyzed carbonaceous substrate is exposed to the carbon-containing gas at a temperature in the range of 600°C to 1200°C.

36. 18. The method of claim 17, wherein the carbon-containing gas comprises ethylene, acetylene, methane, benzene, xylene, carbon dioxide, or a combination thereof.

37. A carbon nanotube hybrid material produced by the method of any one of claims 17 to 36.

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