TW201302451A - Metal or metal oxide coated carbon material and manufacturing method thereof - Google Patents

Abstract

This invention adopts bamboo charcoal to perform with acidification modification to replace carbon nanotube and uses polyalchol process to coat metal or metal oxide, capable of obtaining metal or metal oxide coated carbon material in mass preparation and easily controlling metal size, shape, and uniform distribution of the metal can be easily controlled and its manufacturing method.

Description

A metal or metal oxide coated carbon material and a method of producing the same.

The present invention relates to a metal or metal oxide-coated carbon material which utilizes bamboo charcoal as a carbon material and which coats a metal or a metal oxide to a carbon material by a polyol method, and a method for producing the same.

Carbon material is a widely used material since ancient times. Since carbon is stable in acid or alkali, it is suitable for use as a carrier for various catalysts. In recent years, conductive carbon materials can be widely used in various green energy materials. , such as lithium battery positive and negative electrode additives, LED lampshade additives, fuel cells, etc., capacitors

In order to improve the characteristics of the carbon material, there is a method of coating the metal on the surface of the carbon material, and the copper oxide is coated with copper oxide as described in Non-Patent Document 1, and the non-patent document 2 is coated with platinum on the carbon material.

However, most of the current studies on metal or metal oxide coatings have focused on the use of multi-layered carbon nanotubes, graphenes, etc. as carbon sources, which are still very expensive.

Bamboo is abundant in Taiwan, and bamboo charcoal is also a good source of carbon and low in cost.

Previous technical literature:

Non-Patent Document 1: L.L. Ma, Y.U. Ying, W. Y. Huang, L.P. Zhu, J.L. Li, Y.Y., X.H. Qi, Huaxue Xuebao, 2005, 63(18), 1641-1645.

Non-Patent Document 2: Dongyan Xu, Haizhen Wang, Ping Dai and Qingguo Ye, The Open Catalysis Journal, 2009, 2, 92-95.

An object of the present invention is to replace an expensive carbon nanotube with an inexpensive carbon material, and to coat the carbon material with a metal to form a metal or metal oxide-coated carbon material to improve the characteristics of the conductive powder.

The present inventors have found that in order to solve the above problems, it has been found that the use of high-temperature treated bamboo charcoal as a carbon material, surface modification treatment with a mineral acid, and coating of a metal layer on the surface thereof by a polyol method can be obtained. The present invention has been completed by an inexpensive and well-characterized conductive powder.

According to the present invention, a metal or metal oxide-coated carbon material as described below can be obtained.

(1) A metal or metal oxide-coated carbon material which is attached to a metal surface of a carbon material, characterized in that the carbon material is bamboo charcoal and is subjected to surface modification treatment with a mineral acid by a polyol method. The metal salt is reduced and a metal or metal oxide coating is applied to the surface.

(2) The metal or metal oxide-coated carbon material according to (1), wherein the bamboo charcoal is treated at a high temperature of 1200 ° C or higher.

(3) The metal or metal oxide-coated carbon material according to (1), wherein the inorganic acid is at least one selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, and the like.

(4) The metal or metal oxide-coated carbon material according to (1), wherein the metal salt is selected from the group consisting of metal salts of at least one metal composed of Al, Ni, Cu, Ag, Au, and Pd.

(5) A method for producing a metal or metal oxide-coated carbon material, comprising: a step of surface-modifying a carbon material with a mineral acid; and reducing a metal salt by a polyol method on the surface thereof Metal or metal oxide coating step.

(6) The method for producing a metal or metal oxide-coated carbon material according to (5), wherein the bamboo charcoal is treated at a high temperature of 1200 ° C or higher.

(7) The method for producing a metal or metal oxide-coated carbon material according to (5), wherein the inorganic acid is at least one selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, and the like.

(8) The method for producing a metal or metal oxide-coated carbon material according to (5), wherein the metal salt is selected from the group consisting of metal salts of at least one metal composed of Al, Ni, Cu, Ag, Au, and Pd.

The invention adopts cheap bamboo charcoal as a carbon material, and the surface thereof is modified by acidification, and the metal or metal oxide coated carbon material is obtained by coating the metal or metal oxide on the carbon material by a polyol method, thereby providing an inexpensive product. A metal or metal oxide coated carbon material and a method of producing the same.

Hereinafter, the best mode for carrying out the invention will be described.

One of the features of the present invention is the use of inexpensive bamboo charcoal for carbon materials. Since the bamboo charcoal is hardened by high-temperature carbonization, its structure is close to that of graphite. If some organic surfactant or coupling agent is used for surface modification, the present invention is used in the treatment of CNT surface modification. The method is applied to the modification of bamboo charcoal for high-temperature carbonization, and it is expected to replace the high-cost HMDSZ plasma deposition method instead of MWNTs and CNT as a carrier of the polyol method.

The temperature of the high-temperature carbonized bamboo charcoal is preferably 1200 ° C or more, more preferably 1400 ° C or more, and particularly preferably 1500 ° C or more.

The surface modification of bamboo charcoal is to modify the surface of the bamboo charcoal by a mineral acid to form a functional group such as a hydroxyl group on the surface of the carbon material to improve the surface of the carbon material and the metal interface.

The type of the modifier for the bamboo charcoal modification may be a metal or metal oxide coating to be described later as long as the surface of the bamboo charcoal can be modified, and examples thereof include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and perchloric acid; A compound such as potassium permanganate or potassium dichromate is preferably a mineral acid such as sulfuric acid or nitric acid, and more preferably nitric acid, from the viewpoint of cost and effect.

The temperature of the surface modification treatment is not particularly limited as long as it is a surface property of the bamboo charcoal which can be effectively modified, and the volatility and reaction efficiency of the inorganic acid are considered to be 50 ° C or more at the boiling point of the inorganic acid.

The surface-modified carbon material is reduced by a polyol method to form a metal particle or a film on the surface of the carbon material to cover the metal material to enhance the conductivity of the carbon material.

The polyol method is a method in which a metal salt is dissolved in a polyhydric alcohol, and the reaction is heated to reduce the metal salt to a metal to form fine particles of the metal by the reducing ability of the polyhydric alcohol. The material of the support, such as a carbon material, a porous material, a ceramic powder, or the like, may precipitate fine particles or thin films of metal or metal oxide on the surface of the materials, and metal or metal oxide may be coated on the materials.

The metal used in the metal salt of the present invention may be selected from at least one metal composed of Al, Ni, Cu, Ag, Au, and Pd. Among them, from the viewpoint of improving the conductivity of the carbon material, Al, Ag, Au, and Cu are preferable, and from the viewpoint of use for a catalyst or the like, Cu, Ni, and Pd are preferable.

The type of the metal salt used in the present invention is not particularly limited as long as it is soluble in a suitable solvent to dissociate the metal ion, and examples thereof include a metal halide, a metal cyanide, a nitrate, an acetate, and an oxalate. Sulfate, sulfite, thiosulfate, thiomalate, carbonate, organic acid salt, etc., of which nitrate or acetate is preferred, and acetate is more preferred.

The solvent to be used in the present invention is not particularly limited as long as it can uniformly dissolve the metal salt or the organic metal salt of the precursor, and examples thereof include water, methanol, ethanol, propanol, isopropanol, ethylene glycol, and the like. Alcohols; ethers such as methyl ethyl ether, ethylene glycol methyl ether, and ethylene glycol butyl ether. Among them, water and ethanol are preferred. These solvents may be used alone or in combination of two or more.

The polyol to be used in the present invention is not particularly limited as long as it has two or more hydroxyl groups, and specific examples thereof include ethylene glycol, propylene glycol, butylene glycol, propylene glycol, glycerin, and the like. Glycol and propylene glycol are preferred, and ethylene glycol is more preferred.

When the metal or metal oxide is coated by the polyol method, the solution may also be added with a pH buffer. For example, a pH buffer may be added to a concentration range of 0.1 to 100 g/L for the purpose of stabilizing the pH of the solution, and a phosphoric acid or a phosphoric acid compound, a boric acid or a boric acid compound.

The temperature at which the metal or metal oxide is treated is not particularly limited as long as it can effectively reduce the metal on the surface of the bamboo charcoal. However, considering the volatility and reaction efficiency of the polyol, the boiling point of the inorganic acid is 100 ° C or lower. The above is preferably 180 ° C or lower and 130 ° C or higher. In addition, the temperature at which the metal or metal oxide is applied has a great influence on the particle size of the metal to be coated. Therefore, the metal or the metal oxide or the metal oxide can be used to coat the carbon material, and the desired properties and particle diameters are suitable for determining the metal or The temperature at which the metal oxide is treated.

The metal or metal oxide coating treatment time is not particularly limited as long as it can effectively reduce the metal coating on the surface of the bamboo charcoal, and has a great influence on the density of the coating metal. Therefore, it can also be covered by metal or metal oxide. The use of the carbon-carrying material, the required characteristics, and the particle size are suitable for determining the time of the metal or metal oxide coating treatment.

The concentration of the metal salt in the metal or metal oxide treatment is not particularly limited as long as it can effectively reduce the metal on the surface of the bamboo charcoal, and has a great influence on the ratio of the metal to the bamboo charcoal. Or the use of the metal oxide-coated carbon material, the desired characteristics, and the particle size are suitable for determining the concentration of the metal salt during the metal or metal oxide treatment.

The metal or metal oxide-coated carbon material of the present invention can also be obtained by a suitable reduction treatment to obtain a metal-coated carbon material. The method of reduction is not particularly limited, and examples thereof include reduction annealing such as hydrogen gas or a carbon monoxide atmosphere.

The detailed steps of the embodiments of the present invention are described below, but the present invention is not limited to the embodiments.

First, it is necessary to provide bamboo charcoal powder treated at a high temperature of 1200 ° C or higher as described above, as a carbon material, as in step S100.

Next, the bamboo charcoal powder is put into a solution containing an acidifying agent and heated and stirred, as in step S101.

After the surface modification treatment, the surface modified bamboo charcoal powder is filtered, washed with water several times, and then dried in an oven to obtain an acidified and modified carbon material, as in step S102.

The surface-modified carbon material as described above is charged into a solution containing a metal salt dissolved in the solvent, stirred uniformly, and dried in an oven to obtain a bamboo charcoal/metal salt composite, as shown in step S103.

The bamboo charcoal/metal salt composite is mixed with a polyol and heated and stirred, and the metal salt is reduced and supported on bamboo charcoal, and then centrifuged and dried to obtain a metal or metal oxide-covered carbon material of the present invention, as in step S104.

The microscopic morphology of the metal or metal oxide-coated carbon material of the present invention is observed by a scanning electron microscope.

The crystal structure of the metal or metal oxide-coated carbon material of the present invention is measured by an X-ray diffraction apparatus to determine that a metal or metal oxide is coated on the carbon material.

[Examples]

The present invention will be more specifically described by the following examples, but the present invention is not limited thereto, and may be appropriately modified without departing from the spirit of the invention.

Example 1

2 g of 1500 ° C high temperature bamboo charcoal was mixed with 200 ml of nitric acid, heated to 80 ° C and stirred for 4 hours. Use a filter paper and a funnel and rinse with distilled water to remove the nitric acid and rinse it about five to six times. The acidified bamboo charcoal on the filter paper was washed with alcohol and placed in a beaker, placed in an oven and dried at 120 ° C for about 10 hr to obtain a modified bamboo charcoal. The modified bamboo charcoal was then mixed with aluminum nitrate, water and the mixture in a beaker, and stirred at room temperature for 6 hours. It was again placed in an oven and dried at 75 ° C for 10 hours. When 50 ml of ethylene glycol was added and heated at 140 ° C, 2.5 ml of distilled water was added and heating was continued to 180 ° C for 2 hr. Centrifuge after cooling. After centrifugation, the precipitate was washed out into an aluminum foil cup with absolute ethanol after decantation, and dried in an oven at 60 ° C for 6 hr. The material coated with aluminum in bamboo charcoal can be obtained. Figure 2 shows a scanning electron micrograph. 2, the fine particles P1 of Al are coated on the surface of the carbon material powder P2. The X-ray diffraction of the obtained powder is shown in Fig. 3. The diffraction peak of Al metal can be clearly observed from Fig. 3, and it can be confirmed that aluminum is indeed coated on the carbon material.

Example 2

2 g of 1500 ° C high temperature bamboo charcoal was mixed with 200 ml of nitric acid, heated to 80 ° C and stirred for 4 hours. Use a filter paper and a funnel and rinse with distilled water to remove the nitric acid and rinse it about five to six times. The acidified bamboo charcoal on the filter paper was washed with alcohol and placed in a beaker, placed in an oven and dried at 120 ° C for about 10 hr to obtain a modified bamboo charcoal. Then, the modified bamboo charcoal was mixed with copper acetate, water and a substance in a beaker, and alcohol was added and stirred at room temperature for 6 hours. It was again placed in an oven and dried at 75 ° C for 10 hours. When 50 ml of ethylene glycol was added and heated at 140 ° C, 2.5 ml of distilled water was added and heating was continued to 180 ° C for 2 hr. Centrifuge after cooling. After centrifugation, the precipitate was washed out into an aluminum foil cup with absolute ethanol after decantation, and dried in an oven at 60 ° C for 6 hr. Copper can be obtained on bamboo charcoal. 4, the surface of the carbon material powder P4 is coated with fine particles P3 of Cu ₂ O.

P1. . . aluminum

P2. . . Bamboo charcoal

P3. . . copper

P4. . . Bamboo charcoal

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing an embodiment of the present invention.

2 is a scanning electron micrograph of the aluminum-coated carbon material prepared in Example 1.

4 is an X-ray diffraction pattern of the aluminum-coated carbon material prepared in Example 1.

Figure 5 is a scanning electron micrograph of a copper-coated carbon material prepared in Example 2.

Claims (8)

A metal or metal oxide-coated carbon material, which is attached to a surface of a carbon material, characterized in that the carbon material is bamboo charcoal, and is subjected to surface modification treatment with a mineral acid to form a metal salt by a polyol method. Reduction, metal or metal oxide coating on the surface. The metal or metal oxide-coated carbon material according to claim 1, wherein the bamboo charcoal is treated at a high temperature of 1200 ° C or higher. The metal or metal oxide-coated carbon material according to claim 1, wherein the inorganic acid is at least one selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, and the like. The metal or metal oxide-coated carbon material according to claim 1, wherein the metal salt is selected from the group consisting of metal salts of at least one metal composed of Al, Ni, Cu, Ag, Au, and Pd. A method for producing a metal or metal oxide-coated carbon material, comprising: a step of surface-modifying a carbon material with a mineral acid; and reducing a metal salt by a polyol method to carry out metal or metal on the surface thereof The step of oxide coating. The method for producing a metal or metal oxide-coated carbon material according to claim 5, wherein the bamboo charcoal is treated at a high temperature of 1200 ° C or higher. The method for producing a metal or metal oxide-coated carbon material according to claim 5, wherein the inorganic acid is at least one selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, and the like. The method for producing a metal or metal oxide-coated carbon material according to claim 5, wherein the metal salt is selected from the group consisting of metal salts of at least one metal composed of Al, Ni, Cu, Ag, Au, and Pd.