JP2007031231A - Method for producing carbon cluster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a good quality carbon cluster at low cost and with low energy. <P>SOLUTION: This method for producing a carbon cluster comprises a step of irradiating a laser on a compound containing a carbon atom, a nitrogen atom and a hydrogen atom, and not having a carbon to carbon bond, e.g. a melamine derivative. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel method for producing carbon clusters that can be used for producing carbon materials such as carbon nanotubes and fullerenes.

  Various carbon nanomaterials such as carbon nanotubes and fullerenes have attracted attention in recent years. Since carbon nanotubes and fullerenes have extremely specific electrochemical characteristics, gas storage characteristics, mechanical characteristics, optical characteristics, chemical stability, etc., various basic researches and applied researches have been conducted.

  Carbon nanotubes, fullerenes and the like can be usually produced by an arc discharge method, a laser irradiation method, a chemical vapor deposition (CVD) method or the like. Among these, in the arc discharge method and the laser irradiation method, high-purity graphite is used as a raw material, which is decomposed into atomic carbon or low molecular carbon clusters by arc discharge or laser irradiation, and the presence of a catalyst such as Fe and Ni. Originally, carbon nanotubes, fullerenes, and the like can be obtained by cooling in a reduced-pressure inert gas atmosphere to recombine atomic or low-molecular carbon clusters.

  For example, in Patent Document 1, when performing arc discharge, laser light irradiation is performed on the surface of graphite as an electrode, ablation of carbon atoms is generated, and clusters of the carbon atoms are taken into the plasma at a high speed. A method and apparatus for producing a carbon compound for producing a film of a quasi-one-dimensional structure carbon compound is described.

  Patent Document 2 describes that carbon clusters are generated by laser irradiation of graphite or carbon.

Japanese Patent Laid-Open No. 11-229124 Japanese Patent Laid-Open No. 5-179059

  However, in the conventional method of performing arc discharge or laser irradiation on the raw material graphite, it is necessary to use high-purity graphite as the raw material graphite, and the associated high cost is a problem. In addition, if the raw material graphite is low purity, the purity of the obtained carbon cluster is lowered.

  In addition, graphite itself is a very thermally stable substance. In order to decompose graphite into atomic carbon and low molecular carbon clusters, it is necessary to supply a large amount of energy to the graphite, which also increases the cost. It is a factor.

  The present invention is a carbon cluster manufacturing method capable of manufacturing high-quality carbon clusters at low cost and low energy.

  The present invention is a method for producing a carbon cluster, and includes a step of irradiating a compound containing a carbon atom, a nitrogen atom and a hydrogen atom in a molecule and having no carbon-carbon bond with a laser.

  In the method for producing a carbon cluster, it is preferable that the compound does not contain an atom other than a carbon atom, a nitrogen atom and a hydrogen atom in the molecule.

  In the carbon cluster production method, the compound is preferably a melamine derivative.

  In the carbon cluster manufacturing method, the wavelength of the laser is preferably in the range of 250 nm to 1500 nm.

  In the carbon cluster production method, it is preferable to irradiate the crystalline compound with a laser.

  In the present invention, a high-quality carbon cluster is produced at low cost and low energy by irradiating a compound having a carbon atom, a nitrogen atom and a hydrogen atom in the molecule and having no carbon-carbon bond. It is possible to provide a method for producing a carbon cluster capable of satisfying the requirements.

  Embodiments of the present invention will be described below. In the present specification, the “carbon cluster” refers to an aggregate formed by combining a plurality of carbon atoms. Specifically, it refers to a low molecular carbon cluster having about 2 to 30 carbon atoms, and includes atomic carbon.

  An outline of an example of a carbon cluster production apparatus according to an embodiment of the present invention is shown in FIG. The carbon cluster manufacturing apparatus 1 includes a laser transmitter 10, a substrate mounting table 12, a chamber 14, a pipe 16, a vacuum pump 18, and a heating unit 20.

  In the carbon cluster manufacturing apparatus 1 of FIG. 1, a laser transmitter 10 is installed above a chamber 14 and a substrate mounting table 12 is installed below. A vacuum pump 18 is connected to the chamber 14 via a pipe 16. The chamber 14 is provided with a heating means 20.

The laser transmitter 10 is not particularly limited as long as it can oscillate a laser having a wavelength in the range of 250 nm to 1500 nm. For example, a solid laser such as a YAG laser, a ruby laser, and a glass laser, a GaAs laser, Lasers such as semiconductor lasers such as InGaAsP lasers, gas lasers such as CO ₂ lasers, N ₂ lasers, Ar lasers, and He—Ne lasers, excimer lasers such as KrF lasers, ArF lasers, XeCl lasers, XeF lasers, and dye lasers are used. be able to.

  The substrate mounting table 12 is a table for installing a metal plate 24 such as stainless steel on which the carbon cluster manufacturing raw material 22 is placed. Further, the carbon cluster production raw material 22 may be placed directly on the substrate mounting table 12.

  The vacuum pump 18 is for bringing the inside of the chamber 14 into a vacuum state or a reduced pressure state, and a known vacuum pump can be used.

  The heating means 20 is for controlling the temperature by heating the inside of the chamber 14, and a known heater or the like can be used.

  An operation of the carbon cluster manufacturing method and the carbon cluster manufacturing apparatus 1 according to the present embodiment will be described. In the method for producing a carbon cluster according to the embodiment of the present invention, a carbon atom, a nitrogen atom, and a hydrogen atom are included in the molecule, and a carbon-carbon bond (C—C bond, C═C bond, C≡C bond) is formed. A step of irradiating a compound which does not exist with laser irradiation.

  First, a carbon cluster production raw material 22 which is a compound containing a carbon atom, a nitrogen atom and a hydrogen atom in the molecule and having no carbon-carbon bond is placed on the substrate mounting table 12 in the chamber 14 shown in FIG. A stainless steel plate 24 is installed. Thereafter, the vacuum pump 18 is operated to bring the chamber 14 into a vacuum state. If necessary, the heating means 20 is operated to set the inside of the chamber 14 to a predetermined temperature. After the conditions are met, the laser transmitter 10 irradiates the carbon cluster production raw material 22 with the laser 26 to cut the chemical bonds of the carbon cluster production raw material 22 to generate carbon clusters.

  At this time, since carbon-carbon bonds are not included in the carbon cluster production raw material 22, carbon atoms contained in the compound are vaporized in an atomic state at the time of decomposition. Form a cluster. If a carbon-carbon bond is included in the carbon cluster manufacturing raw material 22, it is difficult for carbon to be in an atomic state at the time of decomposition, so that it is difficult to generate carbon clusters. Nitrogen atoms and hydrogen atoms contained in the carbon cluster production raw material 22 are also vaporized in an atomic state immediately after decomposition, but instantly become nitrogen molecules, hydrogen molecules or ammonia and are stabilized.

  In the present embodiment, the compound used as the carbon cluster production raw material 22 and containing a carbon atom, a nitrogen atom and a hydrogen atom in the molecule and having no carbon-carbon bond is a cyclic compound or a chain compound. Also good. In addition, in order to generate a high-quality carbon cluster in which the content of the cluster other than the carbon cluster consisting of carbon atoms is small in the generated cluster, the above compound contains atoms other than carbon atoms, nitrogen atoms and hydrogen atoms in the molecule. It does not contain, that is, the compound is preferably composed of a carbon atom, a nitrogen atom and a hydrogen atom. If the molecule contains oxygen atoms, sulfur atoms, etc., the content of clusters other than carbon clusters composed of carbon atoms tends to increase in the generated clusters. Here, in the present specification, “not having a carbon-carbon bond” or “not containing an atom other than a carbon atom, a nitrogen atom and a hydrogen atom” in the molecule means a compound used as a raw material 22 for producing a carbon cluster. In the molecule, and a compound “having a carbon-carbon bond” or “containing an atom other than a carbon atom, a nitrogen atom and a hydrogen atom” in the molecule as an impurity in the carbon cluster production raw material 22 Needless to say, it may be included. Further, the compound may be a compound composed of a carbon atom and an element that can exist as a gas.

  As said compound, it is preferable that decomposition temperature is 500 degrees C or less. When the decomposition temperature exceeds 500 ° C., it may be difficult to generate clusters with low energy.

  Moreover, as said compound, a melamine derivative etc. are mentioned, for example. The above compound is preferably a melamine derivative represented by the following structural formula, particularly melamine, because of its low cost, availability, and decomposability at a relatively low temperature.

  In the above structural formula, n is an integer of 1 or more, and n is preferably an integer of 1 to 100. If n exceeds 100, it may be difficult to decompose with a laser.

  Further, the purity required for the above compound is 1.0% or less, preferably 0.1% or less, of impurities. The purity of the compound can be determined by, for example, high performance liquid chromatography or gas chromatography. Moreover, the said compound can be easily refined | purified by the recrystallization method, the column chromatography method, the sublimation purification method, the suspension washing | cleaning method etc., and can be easily made into the said purity.

  When irradiating the carbon cluster manufacturing raw material 22 with a laser, the carbon cluster manufacturing raw material 22 is dissolved in a solvent such as an alcohol-based solvent or a ketone-based solvent, added onto the plate 24, and evaporated to remove the laser. Irradiation may be performed, but in order to generate high-quality carbon clusters, the carbon cluster production raw material 22 is placed on the plate 24 in a crystalline state or in a liquid state, preferably in a crystalline state, and laser irradiation is performed. It is preferable to do.

  The wavelength of the laser to be irradiated is not particularly limited as long as the compound can be decomposed, but is preferably in a range of 250 nm to 1500 nm, which is a wavelength range of a normal laser, and is in a range of 250 nm to 400 nm. More preferred. The laser may be irradiated to the carbon cluster manufacturing raw material 22 in a pulse form.

The output of the laser to be irradiated is not good particularly limited as long as it can decompose the carbon cluster raw material for producing ^22, is preferably in the range of ^{100J / cm 2 ~10kJ / cm 2} , 1kJ / cm 2 ~5kJ / A range of cm ² is more preferable. If the output of the laser used is less than 100 J / cm ² , the carbon cluster production raw material 22 may not be sufficiently decomposed. Further, although it depends on the type of carbon cluster production raw material 22 to be decomposed, an excessive strength exceeding 10 kJ / cm ² is not necessary.

  The irradiation time of the laser to the carbon cluster production raw material 22 is not particularly limited as long as the carbon cluster production raw material 22 can be decomposed, but is preferably in the range of 500 psec to 1 msec, and in the range of 1 nsec to 1 msec. More preferably. If the laser irradiation time is less than 500 psec, the carbon cluster production raw material 22 may not be sufficiently decomposed. Further, although it depends on the type of carbon cluster production raw material 22 to be decomposed, an excessive irradiation time exceeding 1 msec is not necessary.

  The temperature of the ambient atmosphere at the time of laser irradiation of the carbon cluster production raw material 22 is not particularly limited as long as the carbon cluster production raw material 22 can be decomposed, but is preferably in the range of 0 ° C to 350 ° C. . When the temperature of the ambient atmosphere at the time of laser irradiation is less than 0 ° C., a cluster having 20 or more carbon atoms with a large carbon number is hardly generated.

  The pressure (degree of vacuum) in the apparatus at the time of laser irradiation of the carbon cluster production raw material 22 is not particularly limited as long as the carbon cluster production raw material 22 can be decomposed, but is preferably 100 hPa or less. More preferably, it is 10 hPa or less. If the pressure in the apparatus during laser irradiation exceeds 100 hPa, the carbon cluster production raw material 22 may not be sufficiently decomposed.

When irradiating the carbon cluster manufacturing raw material 22 with a laser, an inert gas atmosphere such as N ₂ or Ar may be used instead of making the inside of the chamber 14 into a vacuum state, or a reduced pressure inert gas atmosphere may be used. If oxygen is present at the time of laser irradiation, the generated carbon clusters may react with oxygen, which may reduce the generation efficiency.

  The carbon number of the carbon cluster obtained in this manner varies depending on the generation conditions such as the atmospheric temperature, pressure, and atmospheric gas, but is usually a low molecule having 5 to 30 carbon atoms in the vicinity of room temperature of 20 to 25 ° C. Carbon clusters are obtained. When the atmospheric temperature is raised, the carbon number of the generated carbon cluster increases, and when the atmospheric temperature is lowered, the carbon number of the generated carbon cluster tends to decrease. The carbon number of the obtained carbon cluster can be confirmed by the MASS spectrum method.

  The carbon clusters thus obtained can be recombined by heating in a reduced pressure inert gas atmosphere in the presence of a catalyst, and cooled to obtain carbon nanotubes, fullerenes, and the like.

  As the catalyst, the same catalysts as those used for the production of Fe, Ni, Co, etc., usually carbon nanotubes, fullerenes, etc. can be used. The catalyst may be mixed with the carbon cluster manufacturing raw material 22 and placed on a plate, or a catalyst is placed on the chamber 14 at a position different from the substrate setting table 12, and the catalyst is generated by laser irradiation. Carbon clusters to be contacted may be contacted.

  The heating temperature of the produced carbon clusters for obtaining carbon nanotubes, fullerenes, etc. is not particularly limited as long as the carbon clusters can be recombined, but is preferably in the range of 500 ° C. to 1500 ° C., 500 ° C. It is more preferable to be in the range of ˜1000 ° C. When the temperature of the ambient atmosphere at the time of heating is less than 500 ° C., recombination of carbon clusters may not occur sufficiently, and when it exceeds 1500 ° C., re-decomposition may occur.

Examples of the inert gas used for recombination of carbon clusters include N ₂ and Ar.

  The pressure in the chamber 14 when recombining the carbon clusters is not particularly limited as long as the generated carbon clusters can be recombined, but is preferably 1000 hPa or less, and more preferably 100 hPa or less. When the pressure in the apparatus during cooling exceeds 1000 hPa, recombination of carbon clusters may not occur sufficiently.

  After the carbon clusters are recombined, the inside of the chamber 14 is cooled, so that carbon nanotubes, fullerenes, and the like are generated using the catalyst as a nucleus. The cooling temperature is not particularly limited as long as carbon nanotubes, fullerenes and the like can sufficiently grow, but is preferably in the range of 500 ° C to 1500 ° C, and more preferably in the range of 500 ° C to 1000 ° C. . When the temperature of the ambient atmosphere during cooling exceeds 1500 ° C., re-decomposition of clusters occurs, and when it is lower than 500 ° C., growth of carbon nanotubes, fullerene, etc. may not occur sufficiently.

  As described above, in the present embodiment, a compound containing a carbon atom, a nitrogen atom and a hydrogen atom in the molecule and having no carbon-carbon bond, particularly, containing only a carbon atom, a nitrogen atom and a hydrogen atom in the molecule, Further, by irradiating a compound having no carbon-carbon bond with a laser, a high-quality carbon cluster can be produced with low energy. Further, the vaporization temperature of graphite, which has been conventionally used as a raw material for producing carbon clusters, is 5000 ° C., whereas in the case of the above compound, for example, melamine, the decomposition temperature is much lower at 350 ° C., and it has low energy and good quality. Carbon clusters can be produced.

  In this embodiment, a compound containing a carbon atom, a nitrogen atom, and a hydrogen atom in the molecule and having no carbon-carbon bond has a cost higher than that of high-purity graphite (impurity content is in the order of ppm or less). Can produce good quality carbon clusters at a much lower cost. Moreover, the said compound can be refine | purified easily and the raw material for carbon cluster manufacture can be made into high purity.

  In addition, since high-quality carbon clusters can be easily manufactured, various carbon nanomaterials such as carbon nanotubes and fullerenes can be easily manufactured with high yield.

  Various carbon nanomaterials such as carbon nanotubes, fullerenes, and diamond-like carbons that can be produced from the carbon clusters obtained by the carbon cluster production method according to the present embodiment have excellent electrochemical properties, gas storage properties, mechanical properties. Various electronic materials such as semiconductors, diodes, transistors, emitters for field emission displays (FEDs), sensors, wiring materials; optical materials such as optical switch materials Energy materials such as hydrogen storage materials, catalyst support materials for lithium batteries and fuel cells; composite materials; measuring materials such as scanning probe microscope (SPM) probes; medical materials such as anticancer agents and cosmetics; electronic, optical, It can be applied to all fields such as energy, medical care and diagnosis.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail more concretely, this invention is not limited to a following example.

Example 1
A MALDI-TOF-MASS (Matrix Assisted Laser Desorption / Ionization Time of Flight Mass Spectrometry) device (Shimadzu Corporation AXIMA type) is used as a raw material, consisting of carbon atoms, nitrogen atoms and hydrogen atoms. Not 0.1 mg of melamine (special grade reagent) represented by the following structural formula (1) was placed on a stainless steel plate in a powder state. Thereafter, the chamber was evacuated (10 ⁻⁵ Pa) by a vacuum pump. The temperature in the chamber was set to 25 ° C. After the conditions were met, the compound was irradiated with a nitrogen laser having a wavelength of 337 nm and an intensity of 1 kJ / cm ^{2 in} a pulsed manner for an irradiation time of 1 nsec to generate carbon clusters, and a MASS spectrum was measured. The measurement conditions are as follows. The MASS spectrum of the product is shown in FIG.

  Note that the measurement conditions of the MASS spectrum were raster scan in the range of 1 mm × 1 mm on the sample surface in the reflectron mode, and integrated 100 times. Detection ions were positive ions.

  As can be seen from the MASS spectrum shown in FIG. 2, carbon clusters could be obtained by irradiating the melamine with a laser. By using melamine, which consists of carbon atoms, nitrogen atoms and hydrogen atoms and does not have carbon-carbon bonds, as a raw material, the generated cluster has a low content of clusters other than carbon clusters consisting only of carbon atoms. Carbon clusters (5 to 27 carbon atoms) could be obtained.

It is the schematic which shows an example of the carbon cluster manufacturing apparatus which concerns on embodiment of this invention. It is a figure which shows the MASS spectrum of the product obtained in Example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carbon cluster manufacturing apparatus, 10 Laser transmitter, 12 Board | substrate installation stand, 14 Chamber, 16 Piping, 18 Vacuum pump, 20 Heating means, 22 Carbon cluster manufacturing raw material, 24 Plate, 26 Laser.

Claims (5)

A method for producing a carbon cluster, comprising:
A method for producing a carbon cluster, comprising a step of irradiating a compound containing a carbon atom, a nitrogen atom and a hydrogen atom in a molecule and having no carbon-carbon bond. A method for producing a carbon cluster according to claim 1, comprising:
The said compound does not contain atoms other than a carbon atom, a nitrogen atom, and a hydrogen atom in a molecule | numerator, The manufacturing method of the carbon cluster characterized by the above-mentioned. A method for producing a carbon cluster according to claim 1 or 2,
The said compound is a melamine derivative, The manufacturing method of the carbon cluster characterized by the above-mentioned. It is a manufacturing method of the carbon cluster according to any one of claims 1 to 3,
The method for producing a carbon cluster, wherein the wavelength of the laser is in the range of 250 nm to 1500 nm. It is a manufacturing method of the carbon cluster of any one of Claims 1-4,
A method for producing a carbon cluster, comprising irradiating the compound in a crystalline state with a laser.

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