Fibrous nano-carbon and preparation method thereof

Abstract

This invention relates to fibrous nanocarbons, especially to ladder-structured and pair-structured fibrous nanocarbons, and the preparation thereof. Specifically, the fibrous nanocarbons of this invention, which are designed to be used for molecular composite materials, fuel cell catalyst supports, organic reaction catalyst supports, gas storage of methane and hydrogen, electrodes or conductors for lithium secondary battery, and electrodes for electric double layered capacitor, are characterized by the graphite-like structure with the sp 2 hybrid carbon content of more than 95% per total content; the interlayer spacing (d 002 , d-spacing of C (002) profiles determined by X-ray diffraction method) of 0.3360 nm˜0.3700 nm; the (002) plane stacking of more than 4 layers (or 1.5 nm); the aspect ratio of more than 10; the fiber cross-section width/thickness of 5 nm˜500 nm; and the ladder-like and pair structure with no continuous hollow core.

1 . A fibrous nanocarbon characterized by carbon hexagonal plane or stacking thereof, having one or both directional growth axis, whereby; 
 (1) the sp 2  hybrid carbon content of more than 95% per total content; (2) the interlayer spacing (d 002 , d-spacing of C(002) profiles determined by X-ray diffraction method) of 0.3360 nm˜0.3800 nm; (3) the (002) plane stacking of more than 4 layers and the aspect ratio of more than 20; (4) the fiber cross-section width/thickness of 2.0 nm˜800 nm; (5) the inclination angle of hexagonal plane alignment for each composed carbon nanofibers to the fiber axis of 0˜85 degrees; and carbon hexagonal planes stacking along the fiber axis, forming knots (nodes) at intervals of 5 nm˜100 nm, sharing partly the structure or stacking layers in carbon hexagonal planes of each composed carbon nanofibers and connecting periodically to each other, consequently forming ladder-like structure with open parts between each connection units, through which the inner side of the fibrous nanocarbon is open and connected to the outer space.    
     
     
         2 . A fibrous nanocarbon characterized by carbon hexagonal plane or stacking thereof, having one or both directional growth axis, whereby; 
 (1) the sp 2  hybrid carbon content of more than 95% per total content; (2) the interlayer spacing (d 002 , d-spacing of C(002) profiles determined by X-ray diffraction method) of 0.3360 nm˜0.3800 nm; (3) the (002) plane stacking of more than 8 layers; (4) the width/thickness of fiber cross-section of 2.0 nm˜800 nm; (5) the aspect ratio is more than 20; and (6) bonding of two unit carbon nanofibers with said (1)˜(5) features at 0.5 nm˜30 nm distance by the inter-fiber force between the two unit fibers from the beginning of fiber formation    
     
     
         3 . A preparation method of fibrous nanocarbon according to  claim 1  through catalytic pyrolysis of gaseous or liquid carbon sources, wherein 
 said catalyst is unsupported bulk metal or particulate metal, and said bulk metal or particulate metal are reduced and simultaneously formed into very fine metal particles by hydrogen or hydrogen radical during the catalyst reduction process.    
     
     
         4 . A preparation method of fibrous nanocarbon according to  claim 2  through catalytic pyrolysis of gaseous or liquid carbon sources, wherein 
 said catalyst is unsupported bulk metal or particulate metal, and said bulk metal or particulate metal are reduced and simultaneously formed into very fine metal particles by hydrogen or hydrogen radical during the catalyst reduction process.    
     
     
         5 . A preparation method according to  claim 3 , wherein 
 transition metals such as Fe, Ni or Co active to said carbon sources are used as primary metals; to assist dispersion of said primary metals, the addition of 5˜95 wt % secondary metals inactive to said carbon sources results in formation of fine particle catalyst; and hydrocarbon/hydrogen gas mixtures containing 2˜95v/v % hydrogen are introduced at the rate of 0.5˜30 sccm per 1 mg catalyst at the temperatures of 380˜750° C. for the reaction time of 2 min˜48 h over said fine particle catalyst.    
     
     
         6 . A preparation method according to  claim 4 , wherein 
 transition metals such as Fe, Ni or Co active to said carbon sources are used as primary metals; to assist dispersion of said primary metals, the addition of 5˜95 wt % secondary metals inactive to said carbon sources results in formation of fine particle catalyst; and hydrocarbon/hydrogen gas mixtures containing 2˜95 v/v % hydrogen are introduced at the rate of 0.5˜30 sccm per 1 mg catalyst at the temperatures of 380˜750° C. for the reaction time of 2 min˜48 h over said fine particle catalyst.    
     
     
         7 . A preparation method according to  claim 5 , wherein 
 Said catalyst contains 5˜95 wt % composition ratio of said primary metals and secondary metals.    
     
     
         8 . A preparation method according to  claim 6 , wherein 
 Said catalyst contains 5˜95 wt % composition ratio of said primary metals and secondary metals.    
     
     
         9 . A fibrous nanocarbon characterized by carbon hexagonal plane or stacking thereof, having one or both directional growth axis, whereby; 
 (1) more than 95 wt % of carbon content; (2) 5.5˜550 nm fiber diameters; (3) the aspect ratio of more than 10; (4) and carbon hexagonal planes stacking along the fiber axis forming knots at regular intervals sharing partly the structure or stacking layers in carbon hexagonal planes of each composed carbon nanofibers and connecting periodically to each other, forming open parts between each connection units through which the inner side of the fibrous nanocarbon is open and connected to the outer space with continuous hollow core in the inner space of said fibrous nanocarbon.    
     
     
         10 . A fibrous nanocarbon characterized by carbon hexagonal plane or stacking thereof, having one or both directional growth axis, whereby; 
 (1) more than 95 wt % of carbon content; (2) 5.5˜550 nm fiber diameters; (3) the aspect ratio of more than 10, and bonding of two unit carbon nanofibers with no continuous hollow core in the inner space of said fibrous nanocarbon.    
     
     
         11 . A preparation method of fibrous nanocarbon according to  claim 1  through catalytic pyrolysis of gaseous or liquid carbon sources, wherein 
 iron catalyst or iron-alloy catalysts are used as production catalyst wherein iron is a primary metal catalyst, and nickel, cobalt, manganese, and molybdenum are secondary metals for dispersion of said primary metal; and carbon monoxide/hydrogen gas mixtures containing 0˜25v/v % hydrogen are introduced at the rate of 0.5˜30 sccm per 1 mg catalyst at the temperatures of 400˜700° C. for the reaction time of 2 min˜12 h over said production catalyst.    
     
     
         12 . A preparation method of fibrous nanocarbon according to  claim 9  through catalytic pyrolysis of gaseous or liquid carbon sources, wherein 
 iron catalyst or iron-alloy catalysts are used as production catalyst wherein iron is a primary metal catalyst, and nickel, cobalt, manganese, and molybdenum are secondary metals for dispersion of said primary metal; and carbon monoxide/hydrogen gas mixtures containing 0˜25v/v % hydrogen are introduced at the rate of 0.5˜30 sccm per 1 mg catalyst at the temperatures of 400˜700° C. for the reaction time of 2 min˜12 h over said production catalyst.    
     
     
         13 . A preparation method of fibrous nanocarbon according to  claim 10  through catalytic pyrolysis of gaseous or liquid carbon sources, wherein 
 iron catalyst or iron-alloy catalysts are used as production catalyst wherein iron is a primary metal catalyst, and nickel, cobalt, manganese, and molybdenum are secondary metals for dispersion of said primary metal; and carbon monoxide/hydrogen gas mixtures containing 0˜25 v/v % hydrogen are introduced at the rate of 0.5˜30 sccm per 1 mg catalyst at the temperatures of 400˜700° C. for the reaction time of 2 min˜12 h over said production catalyst.    
     
     
         14 . A preparation method according to  claim 11 , wherein 
 said alloy catalyst according to the alloy kind is composed of 0/1.0˜0.8/0.2 (wt/wt) of Ni/Fe, and 0/1.0˜0.8/0.2 (wt/wt) of Co/Fe or Mn/Fe or Mo/Fe.    
     
     
         15 . A preparation method according to  claim 12 , wherein 
 said alloy catalyst according to the alloy kind is composed of 0/1.0˜0.8/0.2 (wt/wt) of Ni/Fe, and 0/1.0˜0.8/0.2 (wt/wt) of Co/Fe or Mn/Fe or Mo/Fe.    
     
     
         16 . A preparation method according to  claim 13 , wherein 
 said alloy catalyst according to the alloy kind is composed of 0/1.0˜0.8/0.2 (wt/wt) of Ni/Fe, and 0/1.0˜0.8/0.2 (wt/wt) of Co/Fe or Mn/Fe or Mo/Fe.