CN103072968B - Carbon nano composite and preparation method thereof - Google Patents

Abstract

The present invention relates to a carbon nanocomposite material and a preparation method thereof, wherein the carbon nanocomposite material comprises: a carbon nanomaterial whose surface is functionalized; and a metal particle formed on the carbon nanomaterial . The carbon nanocomposite material can be used to remove pollutants in wastewater, and the removal effect is significantly higher than that of existing nanomaterials.

Description

Carbon nanocomposite material and preparation method thereof

technical field

The invention relates to a carbon nanocomposite material and a preparation method thereof.

Background technique

Due to their unique structure and excellent electrical, optical, thermodynamic and mechanical properties, carbon nanomaterials are widely used in many fields such as electrodes, energy storage, catalyst supports, and filtration devices. When carbon materials are combined with metals or metal oxides, they can be used as magnetic materials, catalysts and chemical sensors.

At present, the methods for preparing carbon nanomaterials mainly include arc discharge method, laser sputtering method, and chemical vapor deposition method. Among them, the arc discharge method and the laser sputtering method have limited their application in industrial production due to the disadvantages of expensive equipment, high energy consumption, and many impurities in the product. In the process of preparing carbon nanotubes, the chemical vapor deposition method needs to be firstly used in the process of carbon nanotubes. The catalyst is reduced under high temperature conditions, and impurities such as carbon particles and amorphous carbon are likely to be generated during the preparation process, so there are certain problems. The preparation of carbon materials by solid-state pyrolysis of organometallic precursors has become a research hotspot in recent years because of its simple preparation and high yield. Zhi et al. published several articles reporting the application of solid-state pyrolytic organometallic complexes in the preparation of carbon nanotubes and carbon/metal nanocomposites. Such as literature small2005, 1:210–212, small2005, 1:798–801, Adv. Mater.2008, 20:1727–1731, etc. However, the precursors used in the above methods are complex organometallic complexes, the precursor preparation process is complicated, the use of organic reagents is harmful to the environment, and the pyrolysis process requires high temperature and long time.

In addition, due to the poor compatibility and dispersion of carbon nanotubes, they are prone to self-entanglement or agglomeration, which limits their practical applications. For this reason, people modify the surface of carbon nanotubes through various methods such as direct fluorination reaction, acidification reaction, free radical reaction, electrochemical reaction, etc., but the above methods all have cumbersome reaction steps, long reaction cycle and high cost. , poor environmental performance, low degree of functionalization, great damage to the inherent structure of carbon nanotubes, and unsuitable for mass production.

Layered Double Hydroxide (Layered Double Hydroxide, referred to as hydrotalcite), the general formula is [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^X+ ·A ^n- _x/n ·mH ₂ O, Among them, M ²⁺ and M ³⁺ represent divalent and trivalent metal cations, respectively, and ^An- represents interlayer exchangeable anions. This type of material is an effective precursor for preparing metal catalysts and catalyst supports. Sun et al. prepared carbon nanorings by one-step pyrolysis of dodecylsulfonate intercalated cobalt aluminum hydrotalcite precursor (Adv. Mater. 2012, DOI: 10.1002/adma. 201203108). Xu et al prepared carbon nanoparticles/metal oxide nanocomposites by one-step pyrolysis of cobalt-magnesium-aluminum hydrotalcite intercalated with terephthalic acid (Nano Lett., 2001, 1:703-706). The preparation of carbon materials with laminates containing transition metals and organic anion intercalation hydrotalcites as precursors has attracted people's attention.

Contents of the invention

The present invention aims at solving one of the above technical problems at least to a certain extent or at least providing a useful commercial choice.

In one aspect of the present invention, the present invention proposes a carbon nanocomposite material comprising: a carbon nanomaterial whose surface is functionalized; and metal particles formed on the carbon nanomaterial . The carbon nanocomposite material can be used to remove pollutants in wastewater, such as the removal of the azo dye Congo red, and the removal effect is significantly higher than that of the existing nanomaterials. The inventors have found that 30 mg of the carbon nanocomposite material according to the embodiment of the present invention is added to 50 ml, 100 ppm Congo red solution, and it can be completely adsorbed in 10 minutes. At this time, the adsorption capacity is 167 mg/g, which can be obtained by increasing the concentration of the Congo red solution. The maximum adsorption capacity is 880mg/g.

According to an embodiment of the present invention, the above-mentioned carbon nanocomposite material can also have at least one of the following additional technical features:

According to an embodiment of the present invention, the surface of the carbon nanomaterial carries -OH and -COO- functional groups.

According to an embodiment of the present invention, the metal particles are at least one selected from the group consisting of Co, Ni, Fe, and Cu metal elements or alloys composed of them, and selected from the group consisting of Mg, Zn, and Al oxides. at least one of .

According to an embodiment of the present invention, the carbon nanomaterial is in the form of multi-walled carbon nanotubes, and the metal element or alloy particles are formed in at least one of the inner tube and the tube head of the multi-walled carbon nanotubes.

According to an embodiment of the present invention, the carbon nanomaterial is in the form of a carbon nanolayer, and the metal element or alloy particles are coated on the carbon nanolayer. According to an embodiment of the present invention, when the coating structure is used, the carbon-coated metal element or alloy particles are optionally dispersed in the metal oxide.

In a second aspect of the present invention, the present invention proposes a method for preparing a carbon nanocomposite material. According to an embodiment of the present invention, the method includes: a) forming a salicylate-intercalated layered metal hydroxide precursor containing a transition metal element in a laminate; and b) calcining the precursor to obtain the A carbon nanocomposite material, wherein the carbon nanocomposite material comprises: a carbon nanomaterial whose surface is functionalized; and metal particles formed on the carbon nanomaterial. The aforementioned carbon nanocomposite material can be effectively prepared by using this method.

According to an embodiment of the present invention, the above method for preparing carbon nanocomposites may also have at least one of the following additional technical features:

According to an embodiment of the present invention, the salicylate intercalation layered metal hydroxide precursor described in step a) is prepared by at least one of coprecipitation method, hydrothermal method, roasting recovery method, and ion exchange method. Wherein, in the co-precipitation method and the hydrothermal method, the reaction pH range is 6.5-8.5, and the crystallization temperature range is room temperature-100°C. According to a specific example of the present invention, metal salt solution, alkali solution and salicylate solution are mixed, and at a temperature lower than 100 degrees Celsius, crystallization treatment is carried out, so as to obtain the salicylic acid group containing metal elements in the laminate Intercalated layered metal hydroxide precursors.

According to an embodiment of the present invention, the metal salt is at least one selected from metal nitrate, metal sulfate and metal chloride, and the salicylate is preferably sodium salicylate and potassium salicylate.

According to an embodiment of the present invention, the alkaline solution is at least one selected from NaOH, KOH, and urea.

According to an embodiment of the present invention, calcination of the precursor includes:

The precursor is placed in a tube-type atmosphere furnace, calcined at 500° C. to 1000° C. for 0.2 h to 10 h in a non-oxidizing atmosphere, and then cooled down to room temperature naturally. Preferably, for the laminate containing the Co element system, the firing temperature is 600-1000 degrees Celsius, and the firing time is 1h-10h, and the laminate contains the Ni element system, the firing temperature is 500-1000 degrees Celsius, and the firing time is 0.2h-10h.

According to an embodiment of the present invention, the non-oxidizing atmosphere is composed of at least one of hydrogen and inert gases.

According to an embodiment of the present invention, the inert gas is at least one selected from N ₂ , He or Ar.

In the third aspect of the present invention, the present invention also proposes the use of the above-mentioned carbon nanocomposite material.

The technical method of the present invention can have at least one of the following advantages:

1. According to the embodiments of the present invention, the layered hydroxide precursor used in the preparation of carbon nanocomposites has the characteristics of uniform structure, adjustable composition, simple preparation process, and can be applied to industrial scale production. Water that provides carbon sources The sycylic acid radical is a small organic molecule, and the decomposition product is single, which is beneficial to the preparation of high-purity carbon materials, and the raw materials are easy to obtain, and have no pollution to the environment.

2. According to the embodiment of the present invention, since the layered hydroxide precursor is used, the atomic level dispersion of the layered metal elements makes the metals in the roasted products have higher catalytic activity, thereby effectively reducing the pyrolysis process. Medium growth temperature of carbon nanotube composites, and greatly shorten the firing time.

3. According to the embodiment of the present invention, the prepared carbon nanotube/metal nanocomposite material has uniform structure, high purity, can be mass-produced, and realizes its surface functionalization in one step without any chemical modification.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is the X-ray crystal diffraction spectrum of the cobalt-aluminum layered hydroxide precursor of the salicylate intercalation prepared in Example 1 of the present invention;

Fig. 2 is the scanning electron micrograph of the carbon nanotube/metal nanocomposite material prepared in Example 1 of the present invention;

Fig. 3 is the XRD spectrogram of the carbon nanotube/metal nanocomposite material prepared in Example 1 of the present invention;

Fig. 4 is the Fourier transform infrared data of the carbon nanotube/metal nanocomposite material prepared in Example 1 of the present invention.

Detailed ways

The embodiments of the present invention will be described in detail below, these embodiments are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention. In addition, unless otherwise specified, the raw materials and equipment used below are all commercially available.

Example 1:

Step A: Weigh 11.64g of Co(NO ₃ ) ₂ ·6H ₂ O and 7.5g of Al(NO ₃ ) ₃ ·9H ₂ O and add deionized water to make a 50ml mixed solution, and weigh 12.81g of salicylic acid NaOH was dissolved in 100mL of deionized water, and 8g of NaOH was weighed and added into deionized water to prepare 100mL of a 2M alkali solution. Under mechanical stirring, the mixed salt solution and NaOH solution were added dropwise to the sodium salicylate solution at the same time. During the dropwise addition, the pH of the solution was kept at 7. The resulting slurry was transferred to a high-pressure reactor and crystallized at 100°C for 24 hours. After the crystallization is completed, wait for the temperature to drop to room temperature, wash with deionized water, centrifuge 4 times, and dry at 60°C for 12 hours to obtain a cobalt aluminum hydrotalcite precursor intercalated with salicylic acid radicals.

Step B: After grinding, weigh 1.5g ^of the hydrotalcite precursor, spread it evenly on a porcelain boat and place it in a _tube furnace. The temperature was raised to 600° C. and kept for 2 hours. According to SEM and TEM detection, the obtained pyrolysis product is a composite material of multi-walled carbon nanotubes and cobalt, in which the carbon nanotubes are about 1 μm in length and about 24 nm in diameter, and the metal cobalt is mainly located in the tube head and diameter of the carbon nanotubes , it was found by FT-IR characterization that the surface of the composite had hydroxyl groups and deprotonated carboxyl groups. The results are shown in Figures 1-4.

Wherein, Fig. 1 is the X-ray crystal diffraction spectrogram of the cobalt-aluminum layered hydroxide precursor of the salicylate intercalation prepared in the present embodiment; Fig. 2 is the carbon nanotube/metal nanocomposite material prepared in the present embodiment Scanning electron micrographs show that the product morphology obtained is a carbon nanotube with uniform structure; Fig. 3 is the XRD spectrum of the carbon nanotube/metal nanocomposite material prepared in this embodiment, showing that the product obtained is carbon nanotube and metal Co Figure 4 is the Fourier transform infrared data of the carbon nanotube/metal nanocomposite material prepared in this example, which shows that the surface of the obtained carbon nanotube has a large number of hydroxyl and carboxyl groups, and is a functionalized carbon nanotube.

Example 2:

Step A: Weigh 11.63g of Ni(NO ₃ ) ₂ ·6H ₂ O and 7.5g of Al(NO ₃ ) ₃ ·9H ₂ O and add deionized water to make a 50ml mixed solution, and weigh 12.81g of salicylic acid NaOH was dissolved in 100mL of deionized water, and 8g of NaOH was weighed and added into deionized water to prepare 100mL of a 2M alkali solution. Under mechanical stirring, the mixed salt solution and NaOH solution were added dropwise to the sodium salicylate solution at the same time. During the dropwise addition, the pH of the solution was kept at 7. The resulting slurry was transferred to a high-pressure reactor and crystallized at 100°C for 24 hours. After the crystallization is completed, wait for the temperature to drop to room temperature, wash with deionized water, centrifuge 4 times, and dry at 60°C for 12 hours to obtain a nickel aluminum hydrotalcite precursor intercalated with salicylate radicals.

Step B: After grinding, weigh 1.5g ^of the hydrotalcite precursor, spread it evenly on a porcelain boat and place it in a _tube furnace. The temperature was raised to 500° C. and kept for 2 hours. According to SEM and TEM detection, the obtained pyrolysis product is a carbon/metal nanocomposite material covered with a large number of multi-walled carbon nanotubes on the surface, wherein the carbon nanotubes are about 400nm in length and about 25nm in diameter. The composite surface bears hydroxyl groups and deprotonated carboxyl groups.

Example 3:

Step A: Weigh 11.64g of Co(NO ₃ )2·6H ₂ O and 7.5g of Al(NO ₃ ) ₃ ·9H ₂ O and add deionized water to make a 50ml mixed solution, and weigh 12.81g of salicylic acid NaOH was dissolved in 100mL of deionized water, and 8g of NaOH was weighed and added into deionized water to prepare 100mL of an alkali solution with a concentration of 2M. Under mechanical stirring, the mixed salt solution and NaOH solution were added dropwise to the sodium salicylate solution at the same time. During the dropwise addition, the pH of the solution was kept at 7. The resulting slurry was transferred to a high-pressure reactor and crystallized at 100°C for 24 hours. After the crystallization is completed, wait for the temperature to drop to room temperature, wash with deionized water, centrifuge 4 times, and dry at 60°C for 12 hours to obtain a cobalt aluminum hydrotalcite precursor intercalated with salicylic acid radicals.

Step B: After grinding, weigh 1.5g _of hydrotalcite precursor, spread it evenly on a porcelain boat and place it in a _tube furnace ^. The temperature was raised to 600°C at 5°C/min, and the temperature was kept for 2 hours. After SEM and TEM detection, the obtained pyrolysis product is a composite material of multi-walled carbon nanotubes and cobalt, in which the carbon nanotubes are about 2 μm in length and about 27 nm in diameter, and the metal cobalt is mainly located in the tube head and diameter of the carbon nanotubes , it was found by FT-IR characterization that the surface of the composite had hydroxyl groups and deprotonated carboxyl groups.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations to the present invention. Variations, modifications, substitutions, and modifications to the above-described embodiments are possible within the scope of the present invention.

Claims (5)

1. A carbon nanocomposite, comprising:

a carbon nanomaterial that is surface functionalized; and

elemental metal or alloy particles formed on the carbon nanomaterial,

wherein,

the carbon nano material is in the form of a multi-walled carbon nano tube, and the metal simple substance or the alloy particles are formed in at least one of the tube and the tube head of the multi-walled carbon nano tube; or

The carbon nano material is in the form of a carbon nano layer, the metal simple substance or the alloy particles are coated on the carbon nano layer, wherein the carbon coated metal simple substance or the alloy particles are dispersed in the metal oxide,

the surface of the carbon nano material carries-OH and-COO-functional groups,

the metal simple substance or the alloy particles are at least one selected from the group consisting of Co, Ni, Fe, Cu metal simple substances or alloys consisting of the metal simple substances, and at least one selected from the group consisting of Mg, Zn and Al oxides.

2. A method of preparing the carbon nanocomposite of claim 1, comprising:

a) forming a salicylate intercalation layered metal hydroxide precursor containing transition metal elements on the laminate; and

b) firing the precursor to obtain the carbon nanocomposite,

wherein,

the carbon nanocomposite comprises:

a carbon nanomaterial that is surface functionalized; and

elemental metal or alloy particles formed on the carbon nanomaterial.

3. The method for producing a carbon nanocomposite material according to claim 2,

the salicylate intercalation layered metal hydroxide precursor in the step a) is prepared by at least one of a coprecipitation method, a hydrothermal method, a roasting and restoring method and an ion exchange method,

wherein the reaction pH range in the coprecipitation method and the hydrothermal method is 6.5-8.5, the crystallization temperature range is room temperature-100 ℃,

mixing a metal salt solution, an alkali solution and a salicylate solution, and carrying out crystallization treatment at the temperature lower than 100 ℃ so as to obtain a salicylate intercalation layered metal hydroxide precursor containing metal elements of the laminate.

4. The method for producing a carbon nanocomposite as recited in claim 3, wherein the metal salt is at least one selected from the group consisting of metal nitrate, metal sulfate, and metal chloride, the salicylate is selected from the group consisting of sodium salicylate and potassium salicylate, and the alkali solution is at least one selected from the group consisting of NaOH, KOH, and urea.

5. The method of preparing a carbon nanocomposite as recited in claim 3, wherein firing the precursor comprises:

placing the precursor in a tubular atmosphere furnace, roasting at 500-1000 ℃ for 0.2-10 h in non-oxidizing atmosphere, naturally cooling to room temperature,

wherein the non-oxidizing atmosphere is composed of at least one of hydrogen and an inert gas.