201012747 六、發明說明： 【發明所屬之技術領域】 本發明係關於碳奈米管的製造方法° 【先前技術】201012747 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a method for manufacturing a carbon nanotube. [Prior Art]
碳奈米管（以下，有時簡稱CNT )係由更相當於石墨 的石墨薄片（碳原子排列成六角網眼狀之薄片）被弄圓成 筒狀的立體構造所構成之物質。已知CNT存在有1枚圓筒 狀石墨薄片所構成之單層CNT、和複數枚圓筒狀石墨薄片 i 重疊成同心圓狀之多層CNT。又，一般了解剛合成後的CNT 9 之突端，通常是形成以被稱爲「罩蓋」的半球狀石墨層封 閉之構造。 CNT具有nm級之直徑、和# m~cm級之長度，縱橫比 (CNT長度除以同單位直徑之値）極大，且具有前端之曲 率半徑極小爲數nm〜數十nm之特徴。CNT具有物理性、 機械性皆強韌，化學性、熱安定性優異，對應於圓筒部之 螺旋構造可形成金屬也可形成半導體之特徴。因此，期待 φ CNT在對於發光裝置用電子配線材料、散熱材料、纖維材 料、平面顯示器用電子放出源、電晶體材料、電子顯微鏡 用電子放出源（點光源）之應用。 合成CNT之方法已知有： (1) 在Ar或氮等氣體環境中進行碳棒間之電弧放 電’在陰極上堆積CNT之電弧法（參照專利文獻1)， (2) 在混合有觸媒之石墨表面觸碰YAG雷射等強脈 衝光’將藉此產生之碳煙以電爐加熱，在反應管下游側回 收CNT之雷射蒸發法（參照專利文獻2 )， 201012747 (3)在觸媒金屬微粒子上，將例如甲烷、乙炔、一氧 化碳、苯等低沸點碳化合物予以熱分解之化學氣相成長法 (參照專利文獻3、專利文獻4、非專利文獻1 )等方法。 【先行技術文獻】 【專利文獻】 【專利文獻1】 日本特開2002-201014號公報 【專利文獻2】 日本特開平10-273308號公報 【專利文獻3】 日本特開2000-86217號公報 ^ 【專利文獻4】 日本特開2000-86218號公報A carbon nanotube (hereinafter, abbreviated as CNT) is a structure in which a graphite sheet (a sheet in which carbon atoms are arranged in a hexagonal mesh shape) which is more equivalent to graphite is rounded into a cylindrical shape. It is known that CNTs have a single-walled CNT composed of one cylindrical graphite sheet and a plurality of multi-layered CNTs in which a plurality of cylindrical graphite sheets i are stacked in a concentric shape. Further, it is generally known that the protruding end of the CNT 9 immediately after the synthesis is formed into a structure in which a hemispherical graphite layer called a "cover" is closed. The CNT has a diameter of nm order and a length of #m~cm, and the aspect ratio (the length of the CNT divided by the same unit diameter) is extremely large, and has a characteristic that the curvature radius of the front end is extremely small from several nm to several tens of nm. CNTs are physically and mechanically tough, and are excellent in chemical properties and thermal stability. They correspond to the spiral structure of the cylindrical portion to form a metal or a semiconductor. Therefore, φ CNT is expected to be applied to an electronic wiring material for a light-emitting device, a heat dissipating material, a fiber material, an electron emission source for a flat panel display, a transistor material, and an electron emission source (point source) for an electron microscope. There are known methods for synthesizing CNTs: (1) Arc discharge between carbon rods in a gas atmosphere such as Ar or nitrogen 'Arc method for depositing CNTs on a cathode (see Patent Document 1), (2) Mixed catalysts The surface of the graphite touches a strong pulsed light such as a YAG laser, and the so-called soot is heated in an electric furnace, and a laser evaporation method for recovering CNTs on the downstream side of the reaction tube (refer to Patent Document 2), 201012747 (3) in the catalyst A chemical vapor phase growth method in which a low-boiling carbon compound such as methane, acetylene, carbon monoxide or benzene is thermally decomposed on a metal fine particle (see Patent Document 3, Patent Document 4, Non-Patent Document 1). [PRIOR ART DOCUMENT] [Patent Document 1] Japanese Laid-Open Patent Publication No. Hei. No. 2000-86217 (Patent Document 3) Patent Document 4] Japanese Patent Laid-Open Publication No. 2000-86218
W 【非專利文獻】 【非專利文獻1】 化學物理快報（Chemical Physics Letters)、第 317 卷、第 497〜503 項（2000 年） 【發明内容】 根據（1)及（2)之合成法所獲得之CNT係任一種皆 完全地朝向隨機方向形成聚合狀態。又，亦有含有多量之 奈米碳球（Carbon Nano Capsule)和非晶形粒子等的情形。 φ 又，爲了產生電弧放電、髙脈衝光而必須有高能量，由於 須有高溫而有製造成本變高等問題。 利用（3)之方法，可用較安定的方法製造C NT，但有 原料係使用乙炔、一氧化碳等有害且具有爆炸性等危險性 質之物質、或甲烷等須有作爲高壓氣體之保存且引燃危險 性高之物質等問題。又，使用苯等液體原料時必須使其氣 化等，而有附帶設備大、必須採取複雜之步驟等問題。 因而，本發明之目的在於可提供具有工業規模且安定 地製造碳奈米管之方法。 201012747 本發明者等人係爲了達成上述目的而反複銳意檢討， 發現在液體中有觸媒的存在下，在碳金屬電極間使脈衝電 漿產生的方式可獲得CNT，而達成本發明。 即，根據本發明，係提供： [1] 一種碳奈米管的製造方法，其特徴爲： 於液體中有觸媒的存在下，在碳電極間使脈衝電 漿放電。 [2] 如[1]記載之製造方法，其中該觸媒係至少丨種選 自長週期型之週期表中的第6族~第10族之金屬及其化合 p 物所構成之群。 根據本發明的製造方法，可用較低的能量（例如低電 壓）製造CNT。即’利用在液體中實施的方式，能量擴散 被抑制、能量效率提高，因此較習知技術可用低的量、高 反應速度獲得目的物》 一般而言，CNT係生成在金屬觸媒上，因此以生成物 附著有觸媒成分的狀態被觀測到，但根據本發明，亦發現 φ 在生成物亦即CNT末端不殘留觸媒之習知技術所未能預測 之效果。 【實施方式】 本發明的碳奈米管之製造方法，其特徵係於液體中有 觸媒的存在下，在碳電極間使脈衝電漿放電。作爲碳電極， 可使用石墨、非晶形碳、玻璃碳等任一種碳材料。 作爲電極之形態：爲棒狀、金屬絲狀、板狀等任一種 形態皆可。關於兩極之大小，亦可任一方具有不同大小等 之形狀。又，兩極使用同一碳材料或不同材料皆可，亦可 201012747 使用單一或複數碳材料成型者。 本發明係於液體中生成CNT。作爲可使用之液體（溶 劑），只要是不影響反應者則無特別限制。液體爲2種以上 化合物之混合物亦可。作爲可使用之液體，可舉出如己烷、 辛烷、癸烷、環己烷、環辛烷等飽和烴、苯、甲苯、二甲 苯、萘之芳香族烴，水、甲醇、乙醇、丙醇、丁醇、乙二 醇、丙二醇、1，4 一 丁二醇等醇類，乙酸甲酯、乙酸乙酯、 乙酸丁酯、苯甲酸甲酯、苯二甲酸二甲酯等酯類，四氫呋W [Non-Patent Document] [Non-Patent Document 1] Chemical Physics Letters, Vol. 317, Nos. 497 to 503 (2000) [Summary of the Invention] According to the synthesis method of (1) and (2) Any of the obtained CNT systems completely forms a polymerization state toward a random direction. Further, there are cases in which a large amount of carbon nanocapsules and amorphous particles are contained. φ In addition, in order to generate an arc discharge or a pulsed light, high energy is required, and there is a problem that a high temperature is required and a manufacturing cost is high. According to the method of (3), C NT can be produced by a relatively stable method, but the raw materials are substances which are harmful and explosive, such as acetylene and carbon monoxide, or methane, etc., which are required to be stored as a high-pressure gas and have ignition danger. High substances and other issues. Further, when a liquid material such as benzene is used, it is necessary to vaporize it, and there is a problem that the attached equipment is large and complicated steps must be taken. Accordingly, it is an object of the present invention to provide a method for producing a carbon nanotube having an industrial scale and stably. In order to achieve the above object, the inventors of the present invention have repeatedly conducted an intensive review and found that CNTs can be obtained by generating a pulsed plasma between carbon-metal electrodes in the presence of a catalyst in a liquid, and the present invention has been achieved. That is, according to the present invention, there is provided: [1] A method for producing a carbon nanotube, which is characterized in that a pulsed plasma is discharged between carbon electrodes in the presence of a catalyst in a liquid. [2] The production method according to [1], wherein the catalyst is at least selected from the group consisting of metals of Groups 6 to 10 and a compound of the group of the long-period periodic table. According to the manufacturing method of the present invention, CNT can be produced with a lower energy (e.g., a low voltage). That is, in the manner of being carried out in a liquid, energy diffusion is suppressed and energy efficiency is improved, so that the object can be obtained by a low amount and a high reaction rate by a conventional technique. In general, CNT is formed on a metal catalyst, Although the state in which the catalyst component is attached to the product is observed, according to the present invention, it has been found that φ does not predict the effect of the conventional technique in which the product, that is, the CNT end does not remain in the catalyst. [Embodiment] The method for producing a carbon nanotube according to the present invention is characterized in that a pulsed plasma is discharged between carbon electrodes in the presence of a catalyst in a liquid. As the carbon electrode, any carbon material such as graphite, amorphous carbon or glass carbon can be used. The form of the electrode may be any of a rod shape, a wire shape, and a plate shape. Regarding the size of the two poles, either one of them may have a shape of a different size or the like. In addition, the two poles can be made of the same carbon material or different materials, and the 201012747 can be molded with a single or multiple carbon materials. The present invention is the production of CNTs in a liquid. The liquid (solvent) which can be used is not particularly limited as long as it does not affect the reaction. The liquid may be a mixture of two or more compounds. Examples of the usable liquid include saturated hydrocarbons such as hexane, octane, decane, cyclohexane, and cyclooctane, aromatic hydrocarbons of benzene, toluene, xylene, and naphthalene, water, methanol, ethanol, and C. Alcohol, butanol, ethylene glycol, propylene glycol, 1,4-butanediol and other alcohols, methyl acetate, ethyl acetate, butyl acetate, methyl benzoate, dimethyl phthalate and other esters, four Hydrogen
喃、四氫吡喃、二丙醚、二丁醚、二乙二醇、四乙二醇等 P 醚類。考慮到生成之碳生成物的分散、點燃、氧化性，以 使用飽和烴、芳香族烴及醇類較佳，使用甲醇、乙醇更佳。 液體之使用量未受特別限制，只要兩電極在液體中即 可。更佳爲液體不因電漿之產生而飛散、或因生成物濃度 而失去液擴散性之程度即可。 本發明係於有觸媒的存在之下，實施CNT製造。作爲 觸媒，係使用長週期型之週期表中的第6族〜第10族金屬 φ 及其化合物。觸媒可單獨使用1種，亦可同時或階段性地 使用2種以上。作爲第6族〜第10族金屬，可舉出鐵族金 屬（即，鐵、鈷、鎳）、鉻、鉬、釕、铑、銥、鈀、鉑。作 爲觸媒形狀，係使用板狀、線狀、粒子狀任一種形狀皆可， 但考慮到CNT之生成效率，使用粒狀者較佳。使用之粒狀 物的粒度未受特別限制，但使用細粒子的情形連帶提高 CNT生成，因此通常使用粒徑lnm~100#m之粒子，但考 慮到迴避凝集或生成效率，以2nm~50 # m較佳，而使用 5nm~10/z m之粒子更佳。 201012747 作爲第6族~第10族金屬化合物未受特 可使用如碳化鐵、碳化鎳、碳化鈷之碳化物 氯化鉬、氯化鐵、氯化鎳、氯化鈷、氯化釕 化鈀、氯化鉑、溴化鉻、溴化鉬、溴化鐵、 鈷、溴化釕、溴化铑、溴化鈀、溴化鉑、硫麼 硫酸鈷之礦酸鹽，如乙酸鐵、乙酸鎳、乙酸 丁酸鐵、丁酸鎳、丁酸鈷、乳酸鐵、乳酸鎳 石酸鐵、酒石酸鎳、酒石酸鈷之有機酸鹽， 鉻、乙醯丙酮酸鉬、乙醯丙酮酸鐵、乙醯丙 丙酮酸鈷、乙醯丙酮酸釕、乙醯丙酮酸铑、乙 乙醯丙酮酸鉑、二環戊二烯基鐵、二環戊二 戊二烯基鈷、四（三苯基膦）鈀等有機金屬錯 鐵、五羰基鎳、五羰基鈷等金屬錯合物等》 觸媒可分散或溶解於液體中，而分散 可。考慮到反應效率，以分散於碳電極中較 到使用之觸媒種類、反應條件之影響，因而 φ 觸媒之使用量未受特別限制，只要以不 響之濃度存在即可。.使觸媒分散、或溶解於 下’在0.001莫耳/L~5莫耳/L之範圍較佳， 之情形下’在0.01重量％~1〇重量％之範圍 使脈衝電漿放電之溫度未受特別限制， 液體種類，但通常在室溫~300°(：範圍。超過 使用之溶劑的蒸氣壓上升，因有被電漿點燃 低於室溫之溫度時，溶劑黏度上升，因有損 性的傾向而不佳。 別限制，例如 ，如氯化鉻、 、氯化铑、氯 溴化鎳、溴化 老鐵、硫酸鎳、 鈷、乙酸鈀、 、乳酸鈷、酒 如乙醯丙萌酸 酮酸鎳、乙醯 I醯丙酮酸鈀、 烯基鎳、三環 合物、五羯基 於碳電極中亦 佳，但也會受 無特別限制。 對電漿產生影 液體中之情形 混合於電極中 混合較佳。 亦依據使用之 300°C溫度時， 之虞而不佳， 傷生成物擴散 201012747 本發明中作爲使電漿產生之電壓未受特別限制，通常 在50V~500V之範圍，考慮到安全性、特殊裝置之必要性， 而在60V〜4 00V之範圍較佳，8 0V~3 00V之範圍更佳。 又，使電漿產生之電流未特別受限制，通常在0.1 ~20A 之範圍，考慮到能量效率，以在0.2-10A之範圍較佳。 關於脈衝電漿放電之脈衝間隔未受特別限制，但以 5~100毫秒較佳，6~50毫秒之循環更佳。 每一次脈衝電漿放電的持續時間也因使電漿產生之電 壓及電流而不同，但通常在1~ 50微秒範圍，考慮到放電效 率則以2~30微秒範圍較佳。 本發明中，對電極賦予振動亦可。藉由對電極賦予振 動的方式，使電極間不會有析出之碳化合物滯留，可有效 率地進行放電而較佳。賦予振動之方法未特別受限制，定 期地賦予振動之方法或間歇地賦予振動之方法任一種皆 可。例如作爲賦予振動之手段，若使用電動致動器則可使 振動之振幅及電極間距離穩定化，因而較佳。 實施本發明之環境係於減壓下、加壓下、常壓下任一 種狀態皆可實施，但通常考慮到安全性及操作性，於氮、 氬等非活性氣體下實施較佳。 利用本發明之方法生成的CNT係堆積於液體中，因此 一般方法例如在經進行過濾操作後，可藉由以減壓等操作 去除使用過的液體之方式而獲得CNT。 如以上所獲得之CNT係通常爲管徑在〇.7~50nm之範 圍、管長在50nm〜10# m之範圍者，但視條件亦可獲得該 等範圍外之尺寸者。 201012747 CNT之縱橫比、前端之曲率係可藉由適當調整電漿產 生電壓、電漿產生電流、放電之脈衝間隔、每一次脈衝電 漿放電之持續時間而變化。 實施例 實施例1 在容量300 ml的燒杯秤量200g無水乙醇和O.OOlg乙酸 鐵（III)，實施15分鐘超音波分散。在所獲得的溶液插入 直徑6腿、長度100 mm mm之圓柱狀石墨電極（純度99 %以 上），將電極間固定爲.lmm，利用電動致動器對電極賦予振 動。將各電極連接在交流電源，以200V、2Α進行脈衝電漿 放電。脈衝間隔爲20毫秒，每一次脈衝電漿放電之持續時 間係以1 0微秒進行。開始放電之同時，觀測黑色粉體分散 於液中.，產生反應的情形。繼續30分鐘反應，反應後餾去 乙醇，在殘渣添加20g硝酸，將非晶形部分氧化分解。使 用200g離子交換水，將氧化分解物洗淨除去，以l〇〇°C減 壓乾燥所得結果爲獲得3.14g黑色粉末。 φ 將所獲得之黑色粉末的TEM照片（倍率：10 .萬倍）顯 示在第1圖。從TEM照片判斷所獲得的黑色粉末係管徑約 3nm之CNT。以電極之重量減量分爲100%反應被消耗而計 算，則CNT之產率爲48%。 實施例2 實施例1中，不用乙酸鐵（ΠΙ)作爲觸媒，除了使用 含有1重量％鐵之石墨作爲電極以外’進行與實施例1同 様的操作。將所獲得的黑色粉末之TEM照片顯示在第2圖 (倍率：10萬倍）。從TEM照片判斷所獲得的黑色粉末爲 • 10 - 201012747 管徑約4nm之CNT。 實施例3 實施例1中’除了取代〇.〇〇lg乙酸鐵（III)，使用〇.〇〇lg 乙醯丙酮酸鉬以外’進行與實施例1同様的操作。將所獲 得的黑色粉末之TEM照片（倍率：10萬倍）顯示在第3圖。 從TEM照片判斷所獲得的黑色粉末爲管徑約6nm之CNT 實施例4 實施例1中’除了取代溶劑之200g無水乙醇，使用200g Α 離子交換水以外，進行與實施例1同樣的操作。將所獲得 響 的黑色粉末之TEM照片（倍率：1〇萬倍）顯示在第4圖。 從TEM照片判斷所獲得的黑色粉末爲管徑約4nm之CNT。 TEM-EDX(穿透式電子顯微鏡-會g量分散型X射線分光 法）之觀察結果 以 TEM-EDX( TEM:日本電子製 JEOL JEM-3 00 0F、EDX : NORAN公司製 System SIX)觀測在上述實施例1~4所獲 得的CNT時，未觀測到金屬元素。從該情形得知生成物未 φ 附著有觸媒金靥。 比較例1 在300ml燒杯秤量200g無水乙醇和0.001 g乙酸鐵 (III)，實施15分鐘超音波分散。在所獲得的溶液插入直 徑6麵、長度100腿之圓柱狀石墨電極（純度99%以上）， 將電極間固定爲1 mm，使用電動致動器對電極賦予振動。 將各電極連接在直流電源，以200 V、2A連續放電。開始放 電之同時，觀測黑色粉體分散在液中，引起反應的情形。 繼續30分鐘反應，將溶液離心分離，加入適量無水乙醇進 -11- 201012747 行洗淨和分離。與實施例同樣地，分解非晶形部分，以離 子交換水洗淨去除氧化分解物時，不殘留黑色粉末，而判 斷未生成CNT。 根據本發明的製造方法，可利用較低的電壓等低能量 製造碳奈米管，對産業上之有用性大》 【圖式簡單說明】 第1圖係實施例1所獲得的黑色粉末之穿透式電子顯 微鏡（TEM )照片（倍率：10萬倍）。 第2圖係實施例2所獲得的黑色粉末之TEM照片（倍 率.10萬倍）。 第3圖係實施例3所獲得的黑色粉末之TEM照片（倍 率：10萬倍）。 第4圖係實施例4所獲得的黑色粉末之TEM照片（倍 率：10萬倍）。 【主要元件符號說明】 無。 12-P ethers such as tetrahydropyran, dipropyl ether, dibutyl ether, diethylene glycol, and tetraethylene glycol. In view of dispersion, ignition, and oxidizability of the produced carbon product, it is preferred to use saturated hydrocarbons, aromatic hydrocarbons, and alcohols, and it is more preferable to use methanol or ethanol. The amount of liquid used is not particularly limited as long as the two electrodes are in the liquid. More preferably, the liquid does not scatter due to the generation of the plasma, or the liquid diffusibility is lost due to the concentration of the product. The present invention is directed to the manufacture of CNTs in the presence of a catalyst. As the catalyst, the Group 6 to Group 10 metal φ and its compound in the long period type periodic table are used. The catalyst may be used singly or in combination of two or more kinds at the same time or in stages. Examples of the Group 6 to Group 10 metals include iron group metals (i.e., iron, cobalt, nickel), chromium, molybdenum, rhodium, ruthenium, osmium, palladium, and platinum. As the catalyst shape, any of a plate shape, a wire shape, and a particle shape may be used. However, in consideration of the production efficiency of CNT, it is preferable to use a granular shape. The particle size of the granules to be used is not particularly limited, but the use of fine particles increases the CNT formation, so particles having a particle diameter of 1 nm to 100 #m are usually used, but in consideration of avoidance of agglutination or production efficiency, 2 nm to 50 # m is preferred, and particles of 5 nm to 10/zm are more preferred. 201012747 As a Group 6 to Group 10 metal compound, it is not specifically used, such as iron carbide, nickel carbide, cobalt carbide, molybdenum chloride, iron chloride, nickel chloride, cobalt chloride, palladium chloride, Platinum chloride, chromium bromide, molybdenum bromide, iron bromide, cobalt, cesium bromide, cesium bromide, palladium bromide, platinum bromide, cobalt sulphate, such as iron acetate, nickel acetate, Iron acetate butyrate, nickel butyrate, cobalt butyrate, iron lactate, iron lactate, nickel tartrate, cobalt tartrate, chromium, acenaphthylpyruvate, acenaphthylpyruvate, acetamidine Cobalt acid, ruthenium acetonate, ruthenium acetonate, ruthenium acetate, dicyclopentadienyl iron, dicyclopentadienyl cobalt, tetrakis(triphenylphosphine)palladium, etc. Metal complex such as metal wrong iron, nickel pentoxide or cobalt pentacarbonyl, etc. The catalyst can be dispersed or dissolved in a liquid, and can be dispersed. In view of the reaction efficiency, the amount of the φ catalyst to be used is not particularly limited as long as it is present in the concentration of the catalyst to be used in the carbon electrode, and the reaction conditions are not particularly limited. The temperature at which the pulsed plasma is discharged in the range of 0.01% by weight to 1% by weight in the case where the catalyst is dispersed or dissolved in the range of 0.001 m/L to 5 m/L. Not particularly limited, liquid type, but usually at room temperature ~ 300 ° (: range. Exceeding the vapor pressure of the solvent used, the solvent viscosity rises due to the temperature of the plasma being ignited below room temperature, due to damage Sexual tendency is not good. Don't limit, for example, such as chromium chloride, barium chloride, nickel chlorobromide, old iron bromide, nickel sulfate, cobalt, palladium acetate, cobalt lactate, wine such as acetamidine Nickel acid ketone, acetonitrile I ruthenium pyruvate, ethylenyl nickel, tricyclo compound, and ruthenium are also preferable in the carbon electrode, but it is also not particularly limited. The case where the plasma is produced in a liquid is mixed with The mixture is preferably mixed in the electrode. It is also inferior to the temperature of 300 ° C, and the product is diffused. 201012747 The voltage generated in the plasma is not particularly limited in the present invention, and is usually in the range of 50V to 500V. Taking into account the safety, the necessity of special devices, and in the 60V~4 00V The range is better, and the range of 80 V to 300 V is better. Further, the current generated by the plasma is not particularly limited, and is usually in the range of 0.1 to 20 A, and is preferably in the range of 0.2 to 10 A in consideration of energy efficiency. The pulse interval of the pulsed plasma discharge is not particularly limited, but it is preferably 5 to 100 milliseconds, and the cycle of 6 to 50 milliseconds is better. The duration of each pulse plasma discharge is also caused by the voltage and current generated by the plasma. However, it is usually in the range of 1 to 50 microseconds, and it is preferably in the range of 2 to 30 microseconds in consideration of the discharge efficiency. In the present invention, vibration may be applied to the electrodes, and the electrodes may be provided by vibrating the electrodes. The carbon compound which is precipitated is not retained, and it is preferable to discharge efficiently. The method of imparting vibration is not particularly limited, and a method of periodically imparting vibration or a method of intermittently imparting vibration may be employed. In the vibration means, it is preferable to use an electric actuator to stabilize the amplitude of the vibration and the distance between the electrodes. The environment for carrying out the present invention can be either under reduced pressure, under pressure, or under normal pressure. Implementation However, in view of safety and operability, it is preferably carried out under an inert gas such as nitrogen or argon. The CNTs produced by the method of the present invention are deposited in a liquid, so that the general method can be, for example, after performing a filtration operation. The CNT is obtained by removing the used liquid by a pressure reduction operation or the like. The CNT system obtained as described above generally has a tube diameter in the range of 7. 7 to 50 nm and a tube length in the range of 50 nm to 10 # m, but According to the conditions, the size outside the range can also be obtained. 201012747 The aspect ratio of the CNT and the curvature of the front end can be generated by appropriately adjusting the voltage generated by the plasma, the current generated by the plasma, the pulse interval of the discharge, and the pulse discharge of each pulse. Change in duration. EXAMPLES Example 1 200 g of absolute ethanol and 1.000 g of iron (III) acetate were weighed in a beaker having a capacity of 300 ml, and ultrasonic dispersion was carried out for 15 minutes. A cylindrical graphite electrode having a diameter of 6 legs and a length of 100 mm mm (more than 99% purity) was inserted into the obtained solution, and the electrodes were fixed to .l mm, and the electrodes were vibrated by an electric actuator. Each electrode was connected to an AC power source, and pulse plasma discharge was performed at 200 V and 2 Torr. The pulse interval is 20 milliseconds and the duration of each pulsed plasma discharge is performed at 10 microseconds. At the same time as the discharge was started, it was observed that the black powder was dispersed in the liquid to cause a reaction. The reaction was continued for 30 minutes, and after the reaction, ethanol was distilled off, and 20 g of nitric acid was added to the residue to oxidize and decompose the amorphous portion. Using 200 g of ion-exchanged water, the oxidative decomposition product was washed and removed, and dried under reduced pressure at 10 ° C to obtain 3.14 g of a black powder. φ The TEM photograph (magnification: 100,000 times) of the obtained black powder is shown in Fig. 1. From the TEM photograph, the obtained black powder was a CNT having a diameter of about 3 nm. The CNT yield was 48% as calculated by dividing the weight loss of the electrode into 100% of the reaction. [Example 2] In Example 1, the operation in the same manner as in Example 1 was carried out except that iron acetate (barium) was used as the catalyst except that graphite containing 1% by weight of iron was used as the electrode. The TEM photograph of the obtained black powder is shown in Fig. 2 (magnification: 100,000 times). The black powder obtained from the TEM photograph was a CNT having a diameter of about 4 nm from 10 to 201012747. Example 3 The operation of Example 1 was carried out in the same manner as in Example 1 except that 〇.〇〇lg of iron (III) acetate was used, except that 〇.〇〇lg acetyl acetonate pyruvate was used. A TEM photograph (magnification: 100,000 times) of the obtained black powder is shown in Fig. 3. The black powder obtained from the TEM photograph was a CNT having a diameter of about 6 nm. The same operation as in Example 1 was carried out except that 200 g of anhydrous ethanol was used in the first embodiment except that 200 g of hydrazine-exchanged water was used instead of the solvent. A TEM photograph (magnification: 1 million times) of the obtained black powder is shown in Fig. 4. The black powder obtained from the TEM photograph was judged to be a CNT having a tube diameter of about 4 nm. Observation results of TEM-EDX (transmission electron microscope-g-dispersive X-ray spectroscopy) were observed by TEM-EDX (TEM: JEOL JEM-3 00 0F, EDX: System SIX, manufactured by NORAN) In the CNTs obtained in the above Examples 1 to 4, no metal element was observed. From this case, it was found that the catalyst gold was attached to the product φ. Comparative Example 1 Ultrasonic dispersion was carried out for 15 minutes by weighing 200 g of absolute ethanol and 0.001 g of iron (III) acetate in a 300 ml beaker. A cylindrical graphite electrode having a diameter of 6 faces and a length of 100 legs (purity of 99% or more) was inserted into the obtained solution, and the electrodes were fixed to 1 mm therebetween, and an electric actuator was used to impart vibration to the electrodes. Each electrode was connected to a DC power source and continuously discharged at 200 V and 2 A. At the same time as the discharge was started, it was observed that the black powder was dispersed in the liquid to cause a reaction. The reaction was continued for 30 minutes, the solution was centrifuged, and an appropriate amount of absolute ethanol was added thereto for washing and separation in -11-201012747. In the same manner as in the examples, when the amorphous portion was decomposed and washed with ion-exchanged water to remove the oxidative decomposition product, no black powder remained, and it was judged that no CNT was formed. According to the manufacturing method of the present invention, it is possible to manufacture a carbon nanotube by using a low voltage and the like with low energy, which is industrially useful. [Fig. 1] Fig. 1 is a black powder obtained in Example 1. Transmitted electron microscope (TEM) photograph (magnification: 100,000 times). Fig. 2 is a TEM photograph (magnification: 100,000 times) of the black powder obtained in Example 2. Fig. 3 is a TEM photograph (magnification: 100,000 times) of the black powder obtained in Example 3. Fig. 4 is a TEM photograph (magnification: 100,000 times) of the black powder obtained in Example 4. [Main component symbol description] None. 12-