A method for plasma-modified carbon nanotubes to load metal nanoparticles

Abstract

The present invention relates to a modification and loading method of a carbon product, and in particular to a plasma-modified carbon nanotube, which comprises the following steps: (1) treating the surface of a carbon nanotube with plasma under a specific gas atmosphere to obtain a plasma-modified carbon nanotube; (2) preparing a metal nanoparticle solution: weighing a certain amount of metal salt and preparing it into a metal ion solution of a certain concentration; (3) weighing a certain amount of the plasma-modified carbon nanotube prepared in step (1), and adding it to the solution prepared in step (2); (4) washing the solution in step (3) with deionized water for 2-3 times, separating the carbon nanotube loaded with metal nanoparticles from the solution by suction filtration, and drying the obtained product at 120°C for 12 h to obtain a modified carbon nanotube loaded with metal nanoparticles, wherein the hydrophilicity and adsorption performance of the carbon nanotube are greatly improved without destroying the original structure, thereby increasing the loading amount of the metal nanoparticles.

Description

Technical Field

[0001] The invention relates to a modification and loading method of carbon products, and in particular to a method for plasma-modified carbon nanotubes to load metal nanoparticles. Background Art

[0002] Since carbon nanotubes were first discovered in 1991, based on their unique structure and excellent mechanical, electrical and chemical properties, carbon nanotubes have shown broad application prospects in many fields, attracting the attention of scientists in the fields of materials, physics, electronics, chemistry, etc., and becoming the research frontier and hotspot in the field of international new materials. Carbon nanotubes have better corrosion resistance than carbon black, have obvious catalytic effects on redox reactions, and are suitable as carriers of metal nanoparticles, which can greatly improve their catalytic efficiency. In recent years, certain achievements have been made in the field of carbon nanotube-loaded nanoparticle technology, making breakthrough progress in the application of nanomaterials in the field of catalysis.

[0003] However, since carbon nanotubes are difficult to dissolve in general solvents and have a high radius of curvature, there are many difficulties in loading metal nanoparticles on carbon nanotubes. At present, the commonly used technologies for loading metal nanoparticles on carbon nanotubes are mainly the following: 1. Impregnation method: Place the carbon nanotubes in the catalyst precursor for full impregnation, and select different treatment methods according to different types of catalysts to achieve the loading of metal nanoparticles on the carbon nanotubes. However, the content of loaded metal nanoparticles on the carbon nanotubes prepared by the impregnation method is low; 2. Chemical method: The basic process of the chemical method is to ultrasonically or reflux the carbon nanotubes in sulfuric acid or nitric acid so that the terminal groups of the carbon nanotubes are oxidized to hydroxyl, carboxyl or carbonyl. Then different metal nanoparticles are loaded by reduction, hydrolysis, etc. However, during the strong acid treatment process, the structure of the carbon nanotubes is often destroyed, thereby affecting its original performance; 3. Electrochemical deposition: The electrochemical deposition method uses electrochemical principles to deposit metal nanoparticles on the surface of carbon nanotubes. However, this process is often accompanied by some side reactions (such as the reduction of H+).

[0004] In summary, the traditional method of loading metal nanoparticles on carbon nanotubes has many shortcomings. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for plasma-modified carbon nanotubes to load metal nanoparticles, which can greatly improve the hydrophilicity and adsorption properties of carbon nanotubes without destroying their original structure, thereby increasing the loading amount of metal nanoparticles.

[0006] The technical solution is as follows: a method for plasma-modified carbon nanotubes to load metal nanoparticles, comprising the following steps: (1) In a specific gas atmosphere, the surface of the carbon nanotubes is treated with plasma to obtain plasma-modified carbon nanotubes; (2) Preparing a metal nanoparticle solution: Weigh a certain amount of metal salt and prepare a metal ion solution of a certain concentration; (3) Weighing a certain amount of the plasma-modified carbon nanotubes prepared in step (1) and adding them to the solution prepared in step (2); (4) The solution in step (3) is washed 2-3 times with deionized water, and the carbon nanotubes loaded with metal nanoparticles are separated from the solution by suction filtration. The obtained product is dried at 120° C. for 12 h to obtain modified carbon nanotubes loaded with metal nanoparticles.

[0007] It is further characterized in that in step (1), the specific gas atmosphere is one or a mixture of oxygen, nitrogen, air, argon, etc. In step (1), the specific conditions for plasma modification of carbon nanotubes are: discharge voltage of 50-200 V, current of 1-5 A, power of 100-10000 W, discharge time of 30-60 min, and stirring time interval of 5-10 min; In step (2), the metal nanoparticles are one or more of Ni2+, Zn2+, Cr3+, Pb2+, Hg2+, Fe3+, Co2+, Cu2+, and Cd2+; In step (2), the mass volume concentration of the metal ion solution is 1-15 mg / ml; In step (3), the metal nanoparticles are loaded on the plasma-modified carbon nanotubes under the conditions of 0-50° C. and magnetic stirring for 6-36 hours.

[0008] After adopting the present invention, the carbon nanotubes are modified by a plasma method, which has the advantages of low cost, fewer processes, high controllability, etc. compared with the traditional modification method, and avoids the structural damage caused by the pickling process of the carbon nanotubes. The carbon nanotubes are modified by plasma, and the surface of the carbon nanotubes can be made rougher and more porous, thereby obtaining a larger specific surface area and exposing more active sites. At the same time, functional groups that are beneficial to loading metal nanoparticles are introduced into the carbon nanotubes, and the adsorption capacity of the metal nanoparticles and the carbon nanotubes is enhanced while retaining the pore structure, thereby increasing the loading amount of the metal nanoparticles. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram for comparing the comparator and the embodiment. DETAILED DESCRIPTION

[0010] A method for plasma-modified carbon nanotubes to load metal nanoparticles comprises the following steps: (1) In a specific gas atmosphere, the surface of the carbon nanotubes is treated with plasma, and the specific conditions are: discharge voltage is 100-200V, current is 2-4A, power is 50-8000W, discharge time is 30-60min, and stirring time interval is 5-10min; and the carbon nanotubes modified by plasma are obtained; wherein the specific gas atmosphere is one or a mixture of oxygen, nitrogen, air, and argon. (2) Preparing a metal nanoparticle solution: Weigh a certain amount of metal salt and prepare a metal ion solution of a certain concentration, with a mass volume concentration of 1-15 mg / ml; wherein the metal nanoparticles are one or more of Ni2+, Zn2+, Cr3+, Pb2+, Hg2+, Fe3+, Co2+, Cu2+, and Cd2+; (3) Weigh a certain amount of the plasma-modified carbon nanotubes prepared in step (1), add them to the solution prepared in step (2), and stir them with a magnetic stirrer at 0-50° C. for 12-36 h; (4) The solution in step (3) is washed 2-3 times with deionized water, and the carbon nanotubes loaded with metal nanoparticles are separated from the solution by suction filtration. The obtained product is dried at 120° C. for 12 h to obtain modified carbon nanotubes loaded with metal nanoparticles.

[0011] The following describes in detail several embodiments.

[0012] Embodiment 1: Under nitrogen conditions, carbon nanotubes were modified by dielectric barrier discharge plasma (DBD), the discharge time was 30 minutes, stirring every 5 minutes, the discharge voltage was 200V, and the current was 4A to obtain plasma-modified carbon nanotubes. Cobalt nitrate was weighed and prepared into a 5mg / ml solution. 0.5g of plasma-modified carbon nanotubes was weighed and added to 100ml of 5mg / ml cobalt nitrate solution, and the reaction was stirred magnetically for 12h at 20℃. After the reaction, it was washed with deionized water 3 times, filtered and dried at 120℃ for 12h.

[0013] Example 2 Under air conditions, carbon nanotubes were modified by glow discharge plasma, the discharge time was 40 minutes, stirring every 8 minutes, and the discharge power was 5000W to obtain plasma-modified carbon nanotubes. Ferric chloride was weighed and prepared into a solution of 8 mg / ml. 0.8g of plasma-modified carbon nanotubes was weighed and added to 150ml of 8mg / ml ferric chloride solution. The reaction was stirred magnetically for 18 hours at 20°C. After the reaction, it was washed with deionized water 3 times, filtered and dried at 120°C for 12 hours.

[0014] Example 3 Under argon conditions, carbon nanotubes were modified by dielectric barrier discharge plasma (DBD), the discharge time was 60min, stirring every 10min, the discharge voltage was 100V, and the current was 2A to obtain plasma-modified carbon nanotubes. Weigh chromium nitrate and prepare it into a 15mg / ml solution. Weigh 0.5g of plasma-modified carbon nanotubes, add it to 50ml of 15mg / ml chromium nitrate solution, and react for 15h under magnetic stirring at 20℃. After the reaction, wash it with deionized water 3 times, filter it, and dry it at 120℃ for 12h.

[0015] Example 4 Under the condition of volume flow ratio of N2:O2=1:1, carbon nanotubes were modified by glow discharge plasma, the discharge time was 30min, stirring every 10min, and the discharge power was 8000W to obtain plasma-modified carbon nanotubes. Nickel nitrate was weighed and prepared into a 12mg / ml solution. 0.6g of plasma-modified carbon nanotubes was weighed and added to 80ml of 12mg / ml nickel nitrate solution. The reaction was stirred magnetically at 20℃ for 18h. After the reaction, it was washed with deionized water 3 times, filtered and dried at 120℃ for 12h.

[0016] Example 5 Under argon conditions, carbon nanotubes were modified by radio frequency plasma, with a radio frequency power of 50W, a pressure of 20Pa, and a discharge time of 60min to obtain plasma-modified carbon nanotubes. Weigh chloroplatinic acid and prepare a 1mg / ml solution. Weigh 0.1g of plasma-modified carbon nanotubes and add them to 50ml of 1mg / ml chloroplatinic acid solution. At 20°C, stir magnetically to react for 36h. After the reaction, wash with deionized water 3 times, filter and dry at 120°C for 12h.

[0017] Figure 1 In the comparative example, the carbon nanotubes are not treated with plasma, and are compared with the carbon nanotubes modified with plasma in the embodiment of the present invention.

[0018] The present invention adopts plasma to modify carbon nanotubes, which can make the surface of carbon nanotubes rougher and more porous, obtain a larger specific surface area, and expose more active sites. At the same time, functional groups that are beneficial to the loading of metal nanoparticles are introduced into the carbon nanotubes, and the adsorption capacity of metal nanoparticles and carbon nanotubes is enhanced while retaining the pore structure. The obtained modified carbon nanotubes loaded with metal nanoparticles have better conductivity, are conducive to electron transfer, and thus have better catalytic performance.

[0019] In the present invention, plasma is used to modify carbon nanotubes, and the required temperature is low, and less carbon nanotubes are lost during the modification process. Compared with the direct impregnation method, the loading amount of metal nanoparticles is greatly increased, and the catalytic efficiency is improved; compared with the chemical method, the damage to the structure of carbon nanotubes caused by acid washing and the pollution of the environment by waste water after acid washing are avoided; compared with the electrochemical deposition method, the whole process is more controllable, and no by-products appear.

[0020] In summary, the method for plasma-modified carbon nanotubes loaded with metal nanoparticles proposed in the present invention is simple, efficient, easy to operate, and has more advantages than traditional methods.

Claims

1. A method for plasma-modified carbon nanotubes to load metal nanoparticles, characterized in that: It includes the following steps: (1) In a specific gas atmosphere, the surface of the carbon nanotubes is treated with plasma to obtain plasma-modified carbon nanotubes; (2) Preparing a metal nanoparticle solution: Weigh a certain amount of metal salt and prepare a metal ion solution of a certain concentration; (3) Weighing a certain amount of the plasma-modified carbon nanotubes prepared in step (1) and adding them to the solution prepared in step (2); (4) The solution in step (3) is washed 2-3 times with deionized water, and the carbon nanotubes loaded with metal nanoparticles are separated from the solution by suction filtration. The obtained product is dried at 120° C. for 12 h to obtain modified carbon nanotubes loaded with metal nanoparticles.

2. The method for plasma-modified carbon nanotubes to load metal nanoparticles according to claim 1, characterized in that: In step (1), the specific gas atmosphere is one or a mixture of oxygen, nitrogen, air, and argon.

3. The method for plasma-modified carbon nanotubes to load metal nanoparticles according to claim 1, characterized in that: In step (1), the specific conditions for plasma modification of carbon nanotubes are: discharge voltage of 50-200 V, current of 1-5 A, power of 100-10000 W, discharge time of 30-60 min, and stirring time interval of 5-10 min.

4. The method for plasma-modified carbon nanotubes to load metal nanoparticles according to claim 1, characterized in that: In step (2), the metal nanoparticles are one or more of Ni2+, Zn2+, Cr3+, Pb2+, Hg2+, Fe3+, Co2+, Cu2+, and Cd2+.

5. The method for plasma-modified carbon nanotubes to load metal nanoparticles according to claim 1, characterized in that: In step (2), the mass volume concentration of the metal ion solution is 1-15 mg / ml.

6. The method for plasma-modified carbon nanotubes to load metal nanoparticles according to claim 1, characterized in that: In step (3), the metal nanoparticles are loaded on the plasma-modified carbon nanotubes under the conditions of 0-50° C. and magnetic stirring for 6-36 hours.

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