TWI427026B - Method for metal plating carbon nanotubes - Google Patents

Description

Metal coating method for carbon nanotubes

The present invention relates to a carbon nanotube, and more particularly to a method of metal plating on a carbon nanotube using a metal plating treatment agent.

Carbon Nanotube (CNT) was discovered by Professor Sumio Iijima, a senior researcher at NEC in Japan, when he observed carbon clusters by a transmission electron microscope when he produced C60 by arc discharge in 1991. According to different growth modes, the shape of the carbon nanotubes is generally divided into a single-layer carbon nanotube having a diameter of several nanometers, and a multilayer carbon nanotube having a diameter of several tens of nanometers. The wall thickness is only a few nanometers. Due to the different arrangement of carbon atoms in the carbon nanotubes, a carbon nanotube with semiconductor or conductor characteristics can be obtained, which makes it not only usable in field emission displays, but also in hydrogen storage materials, biomedicine, and electricity. Crystals and other aspects. In addition, among the many display technologies, Field Emission Display (FED) claims to be the newest technology to replace LCD. The technical principle of FED is similar to that of traditional cathode ray tube (CRT), so it has a small starting voltage and a high current density. The principle of field emission is that the radius of curvature of the electrode tip is small, and electrons are easy to be emitted. The electron gun also uses this principle to make electrons. Therefore, the principle of the carbon nanotube field emission display is the same as that of the electron gun. Since the carbon nanotube has a small diameter, the electron is more easily excited, and therefore, the carbon nanotube (Carbon Nanotube; CNT) is a material with good field emission characteristics among alternative materials for many field emitters.

However, in order to make the carbon nanotubes exert their characteristics, in practical applications, the surface of the carbon nanotubes is plated with a metal plating by an electroless metal plating method. The electroless metal plating method is one of methods for forming a metal film on a substrate having no conductivity, and generally uses a method of activating a noble metal (e.g., palladium) which is previously adhered to a substrate as a catalyst. And do the electroless plating before use. Heretofore, a method of adsorbing Pd on a substrate by immersion in an aqueous solution of PdCl 2 after treatment with a solution of hydrochloric acid of SnCl 2 , or a solution of Pd by a colloidal solution containing Sn and Pd has been used. The method of supporting on the surface, but these methods have many problems such as the complicated processing steps required to use Sn. Therefore, there are many methods for forming a decane coupling agent having a functional group with such a noble metal, such as: Japanese Patent Laid-Open No. 59-52701, Japanese Laid-Open Patent Publication No. Sho 60-181294, Japan The contents disclosed in Japanese Laid-Open Patent Publication No. SHO-61-194183 and Japanese Patent Application Laid-Open No. Hei No. 3-44149 are all precious metal (e.g., Pd) methods capable of supporting the surface as a catalyst for an electroless plating layer, even There are also electroless plating methods and metal plating treatments which can be easily applied to powdery materials or mirror materials, as disclosed in Taiwan Patent No. 438,905.

However, when the carbon nanotubes are plated with a metal plating by the method of electroless metal plating, the carbon nanotubes cannot be individually dispersed and then plated with metal plating, as shown in the first and second figures, that is, It is because the carbon nanotubes 10 are aggregated due to the mutual force and electrostatic force between the carbon nanotubes 10, so after the nickel plating layer 20 is applied, the surface of the carbon nanotube 10 is not sufficiently plated with the nickel plating layer 20; It is not easy to disperse the tubes individually, so many related research or practical application production techniques will make good and bad results and reproduce Sex is very unstable.

In view of the above, the object of the present invention is to provide a method for metal plating of carbon nanotubes, which not only can disperse the carbon nanotubes individually, but also fully metallize the surface of the structure, and improve the conductive transmission characteristics of the carbon nanotubes themselves. In the past, there was a problem of uneven distribution of plating due to aggregation between carbon nanotubes.

In order to achieve the foregoing object, the metal plating method of the carbon nanotube of the present invention is characterized in that the carbon nanotubes are sequentially placed in a dispersion liquid and a metal plating treatment agent, or the carbon nanotubes are placed in a metal plating treatment. In the mixed solution of the agent and the dispersion, the carbon nanotubes are dispersed individually by ultrasonic vibration, and then the electroless plating layer is used to obtain the metal-coated carbon nanotubes, and the dispersion is a low-carbon alcohol solution.

Compared with the prior art, the invention utilizes the characteristics that the physical and chemical inertness of the carbon nanotube itself does not react with other materials, and can not only enable the carbon nanotubes to be used in the metal plating treatment when using the metal plating treatment agent. It can disperse evenly and make the surface of the carbon nanotube structure fully metal-plated, which solves the problem of uneven distribution of coatings in the past. Even when used in field emission display, it can improve the carbon nanotube itself under the action of electric field. The field enhancement factor makes the electron beam easier to release and increases the amount of current emitted.

The present invention will be further described below in conjunction with the drawings and embodiments.

Please refer to the third to fifth figures, which are the flow and results of the metal plating method of the carbon nanotube of the present invention, wherein an embodiment of the present invention first takes a carbon nanotube 30 of an appropriate length on the device. The carbon nanotubes 30 were placed in an alcohol solution, shaken for three seconds with ultrasonic waves, and then ultrasonically cleaned for three seconds with water, and the washing step was repeated three times. The components of the chemical solutions used in the preferred embodiment and the operating conditions of the mixing are as follows: Operating conditions: (1) sodium hydroxide (NaOH), water (H ₂ O) and alcohols (C _n H _{2n +1} OH) of a mixed solution (an alcohol-containing solution, preferably 5 to 30%), 80 ℃; (ii) sulfuric acid (H ₂ SO _4), water (H ₂ O) with alcohols (C _n H _{2n + 1} Mixed solution of OH) (5~30% of alcohol solution is preferred), room temperature; (3) Palladium activation solution (containing palladium chloride (PdCl ₂ ), stannous chloride (SnCl ₂ ), hydrochloric acid (HCl) , a mixed solution of water (H ₂ O) and an alcohol (C _n H _2n+1 OH) (5-30% of an alcohol-containing solution is preferred), 30-45 ° C; (4) nickel sulfate (NiSO ₄ ) , sodium pyrophosphate (Na ₄ P ₂ O ₇ ), sodium hypophosphite (NaH ₂ PO ₂ ), a mixture of water and alcohol (5-30% alcohol solution is preferred), 50-60 ° C, pH 10~ 11.

Step 1: Put the cleaned carbon nanotubes into the solution of operating condition (1), perform ultrasonic vibration for 10 seconds, continue to soak and stir for about 3 minutes, then clean the carbon nanotubes with water and ultrasonically oscillate 5 second.

Step 2: Next, put the carbon nanotubes into the solution of the operating condition (2), perform ultrasonic vibration for 10 seconds, continue to soak and stir for about 1 minute, then rinse the carbon nanotubes with water and ultrasonically oscillate for 5 seconds.

Step 3: Then place the carbon nanotubes in the solution of the operating condition (3) After ultrasonic vibration for 3 seconds, continuous soaking and stirring for about several minutes, the carbon nanotubes were washed with water and ultrasonically shaken for 5 seconds.

Step 4: Finally, put the carbon nanotubes into the solution of operating condition (4), perform ultrasonic vibration for 20 seconds and stir slightly, then wash the carbon nanotubes with water and ultrasonically oscillate for 5 seconds to place the carbon nanotubes. The carbon nanotube 30 having the nickel plating layer 40 is completed by removing the drying.

The above-mentioned use of the solution of the operating conditions (1) to (4) and the use of the metal plating treatment agent, and the use of the ultrasonic shock metal plating method, which not only allows the carbon nanotubes 30 to be uniformly dispersed, but also allows the carbon nanotubes to be dispersed. The surface wall of the structural surface is fully plated with nickel plating layer 40, which can improve the conductive transmission characteristics of the carbon nanotube itself, and solve the problem of uneven distribution of the plating layer due to the aggregation between the carbon nanotubes.

In another preferred embodiment of the present invention, the method for metal plating of carbon nanotubes, the composition of each step and the chemical solution and the operating conditions are as follows: Operating conditions: (1) Palladium activation solution (containing palladium chloride (PdCl ₂ )) , a mixed solution of stannous chloride (SnCl ₂ ), hydrochloric acid (HCl), water (H ₂ O) and alcohol (C _n H _2n+1 OH) (5~30% of the alcohol-containing solution is the best) , 30-45 ° C; (2) nickel sulfate (NiSO ₄ ), sodium pyrophosphate (Na ₄ P ₂ O ₇ ), sodium hypophosphite (NaH ₂ PO ₂ ), a mixture of water and alcohol (alcohol-containing solution) 5~30% is the best), 50-60 ° C, pH 10~11.

Step 1: Cut the carbon nanotube into about 3-5mm each section, add a proper amount of nitric acid and sulfuric acid mixture (nitric acid: sulfuric acid = 1:3), oscillate and heat with ultrasonic waves. After continuing to 65 to 75 ° C for 90 minutes, it is diluted with 4 times or more of water and filtered, and the collected carbon nanotubes 30 are washed with water several times to obtain a dispersed carbon nanotube.

Step 2: The washed carbon nanotubes are sequentially placed in the solution of the operating condition (1), respectively subjected to ultrasonic vibration for 3 minutes and 1 minute, and then filtered, and the carbon nanotubes 30 on the filter paper are washed with water several times.

Step 3: Put the cleaned carbon tube into the solution of operating condition (2), perform ultrasonic vibration for 10 seconds, filter, wash the carbon nanotube on the filter paper several times, and then dry it, that is, complete with nickel plating 40 Nano carbon tube 30.

The invention not only enables the carbon nanotube treatment agent to be uniformly dispersed when the metal plating layer is used, but also can fully coat the surface of the surface of the carbon nanotube structure, thereby solving the problem of uneven distribution of the plating layer in the past. Of course, for the present invention, the most important thing is to use various solutions used in various operating conditions in combination with the metal plating treatment agent, and use ultrasonic vibration to promote the individual dispersion of the carbon nanotubes, so as to facilitate the implementation of the metal electroless plating method. Further, a carbon nanotube of the metal plating layer is obtained. For example, the various solutions used in the various operating conditions described above are alcohol solutions, surfactants with thiol functional groups, surfactants with sulfonic acid functional groups, or both thiol functional groups and sulfonic acid functional groups. All of the surfactants (such as: HS-(CH2)n-SO ₃ Na), and the metal plating is performed by copper or nickel or gold, or by using other metal plating treatment agents, etc. It is within the scope of the invention and will not be described again here.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above is only the preferred embodiment of the present invention. The scope of the present invention is not limited to the above-described embodiments, and equivalent modifications or variations made by those skilled in the art to the spirit of the present invention are intended to be included in the scope of the following claims.

10‧‧‧Nano Carbon Tube

20‧‧‧ Nickel plating

30‧‧‧Nano Carbon Tube

40‧‧‧ Nickel plating

The first figure is a schematic diagram of nickel metal plating on a carbon nanotube by a conventional metal plating method; the second drawing is an enlarged schematic view of the nickel metal of the first figure after being plated on a carbon nanotube; the third drawing is the present invention. The fourth drawing is a schematic diagram of nickel metal plating on a carbon nanotube according to a preferred embodiment of the present invention; and the fifth drawing is an enlarged schematic view of nickel metal plating on a carbon nanotube in the fourth drawing.

Claims (13)

A metal plating method for carbon nanotubes, comprising the steps of: providing an appropriate amount of carbon nanotubes; placing the aforementioned carbon nanotubes in a dispersion and a metal plating treatment agent, and using ultrasonic vibration to make nano carbon The tubes are uniformly dispersed uniformly; the carbon nanotubes are electrolessly plated, and the surface of the surface of the carbon nanotube structure is sufficiently plated with a metal plating layer to obtain a carbon nanotube which has been uniformly plated with a metal plating layer. A metal plating method using a metal plating treatment agent according to the first aspect of the patent application scope, wherein a carbon nanotube is first placed in a dispersion, and then in a supersonic wave together with a carbon nanotube and a dispersion After the vibration, the carbon nanotubes are dispersed and uniformly dispersed, and then the metal plating treatment agent is used for the electroless plating layer. According to the metal plating method of the carbon nanotube according to claim 1, wherein the dispersion is first added to the metal plating treatment agent, and then the carbon nanotube is placed in the solution of the metal plating treatment agent and dispersion. Then, ultrasonic vibration is used to separately disperse and disperse the carbon nanotubes in the solution of the metal plating treatment agent and the dispersion liquid, and then perform an electroless plating layer to obtain the metal coated carbon nanotubes. The metal plating method of the carbon nanotube according to Item 1 or 2 or 3 of the patent application scope, wherein the dispersion is an alcohol solution, and a mixed solution containing 5 to 30% of the alcohol solution is prepared. The carbon nanotubes were immersed in the mixed solution and stirred. A metal plating method according to the invention of claim 4, wherein the dispersion has a molecular formula of CnH2n+1OH. Metal plating method for carbon nanotubes according to item 5 of the patent application scope Wherein the molecular formula n is less than 5, and the dispersion is a low carbon number alcohol solution. The metal plating method of the carbon nanotube according to claim 1 or 2 or 3, wherein the surfactant having a thiol functional group is used as a dispersion, and the alcohol-containing solution is prepared. 5~30% of the mixed solution, soak the carbon nanotubes in the mixed solution and stir. The metal plating method of the carbon nanotube according to claim 1 or 2 or 3, wherein the surfactant having a sulfonic acid functional group is used as a dispersion, and the alcohol-containing solution is prepared. 5~30% of the mixed solution, soak the carbon nanotubes in the mixed solution and stir. A metal plating method for use in a carbon nanotube according to the first or second or third aspect of the patent application, wherein a surfactant having a thiol functional group and a sulfonic acid functional group is used as a dispersion. Further, a mixed solution containing 5 to 30% of the alcohol-containing solution was prepared, and a carbon nanotube was immersed in the mixed solution and stirred. According to the metal plating method of the carbon nanotube according to claim 9, wherein the surfactant of the sulfonic acid functional group is HS-(CH2)n-SO3Na. The metal plating method of the carbon nanotube according to the first or second aspect or the third aspect of the patent application, wherein the electroless plating layer is performed with copper. The metal plating method of the carbon nanotube according to the first or second aspect or the third aspect of the patent application, wherein the electroless plating layer is performed with nickel. The metal plating method of the carbon nanotube according to the first or second aspect or the third aspect of the patent application, wherein the electroless plating layer is performed with gold.