US20210189598A1 - Novel carbon nanofiber and method of manufacture - Google Patents
Novel carbon nanofiber and method of manufacture Download PDFInfo
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- US20210189598A1 US20210189598A1 US17/269,215 US201917269215A US2021189598A1 US 20210189598 A1 US20210189598 A1 US 20210189598A1 US 201917269215 A US201917269215 A US 201917269215A US 2021189598 A1 US2021189598 A1 US 2021189598A1
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- 239000002134 carbon nanofiber Substances 0.000 title claims abstract description 46
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000004519 manufacturing process Methods 0.000 title abstract description 6
- 229920002239 polyacrylonitrile Polymers 0.000 claims abstract description 71
- 238000011282 treatment Methods 0.000 claims abstract description 48
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000002243 precursor Substances 0.000 claims abstract description 37
- 238000001523 electrospinning Methods 0.000 claims abstract description 35
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 26
- 230000000087 stabilizing effect Effects 0.000 claims abstract description 16
- 239000002121 nanofiber Substances 0.000 claims abstract description 15
- 238000000197 pyrolysis Methods 0.000 claims abstract description 14
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 12
- 239000000126 substance Substances 0.000 claims abstract description 10
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 7
- 239000010439 graphite Substances 0.000 claims abstract description 7
- 239000000835 fiber Substances 0.000 claims description 34
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 18
- 229910052799 carbon Inorganic materials 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 16
- 239000002904 solvent Substances 0.000 claims description 14
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 10
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 6
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 5
- 238000005098 hot rolling Methods 0.000 claims description 5
- 239000001301 oxygen Substances 0.000 claims description 5
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- 238000001816 cooling Methods 0.000 claims description 2
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- PSVRFUPOQYJOOZ-QNPWAGBNSA-O 2-[hydroxy-[(2r)-2-[(5z,8z,11z,14z)-icosa-5,8,11,14-tetraenoyl]oxy-3-octadecanoyloxypropoxy]phosphoryl]oxyethyl-trimethylazanium Chemical compound CCCCCCCCCCCCCCCCCC(=O)OC[C@H](COP(O)(=O)OCC[N+](C)(C)C)OC(=O)CCC\C=C/C\C=C/C\C=C/C\C=C/CCCCC PSVRFUPOQYJOOZ-QNPWAGBNSA-O 0.000 description 29
- 230000005684 electric field Effects 0.000 description 8
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- XMWRBQBLMFGWIX-UHFFFAOYSA-N C60 fullerene Chemical class C12=C3C(C4=C56)=C7C8=C5C5=C9C%10=C6C6=C4C1=C1C4=C6C6=C%10C%10=C9C9=C%11C5=C8C5=C8C7=C3C3=C7C2=C1C1=C2C4=C6C4=C%10C6=C9C9=C%11C5=C5C8=C3C3=C7C1=C1C2=C4C6=C2C9=C5C3=C12 XMWRBQBLMFGWIX-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- ZYSSNSIOLIJYRF-UHFFFAOYSA-H Cl[Ir](Cl)(Cl)(Cl)(Cl)Cl Chemical compound Cl[Ir](Cl)(Cl)(Cl)(Cl)Cl ZYSSNSIOLIJYRF-UHFFFAOYSA-H 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 239000011425 bamboo Substances 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
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- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 229960003638 dopamine Drugs 0.000 description 1
- YAGKRVSRTSUGEY-UHFFFAOYSA-N ferricyanide Chemical compound [Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] YAGKRVSRTSUGEY-UHFFFAOYSA-N 0.000 description 1
- 229910003472 fullerene Inorganic materials 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- 230000003287 optical effect Effects 0.000 description 1
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 1
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Images
Classifications
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- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
- D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
- D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
- D01F9/225—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles from stabilised polyacrylonitriles
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D1/00—Treatment of filament-forming or like material
- D01D1/02—Preparation of spinning solutions
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
- D01D10/02—Heat treatment
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D11/00—Other features of manufacture
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/0007—Electro-spinning
- D01D5/0061—Electro-spinning characterised by the electro-spinning apparatus
- D01D5/0092—Electro-spinning characterised by the electro-spinning apparatus characterised by the electrical field, e.g. combined with a magnetic fields, using biased or alternating fields
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/12—Stretch-spinning methods
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F11/00—Chemical after-treatment of artificial filaments or the like during manufacture
- D01F11/10—Chemical after-treatment of artificial filaments or the like during manufacture of carbon
- D01F11/12—Chemical after-treatment of artificial filaments or the like during manufacture of carbon with inorganic substances ; Intercalation
- D01F11/122—Oxygen, oxygen-generating compounds
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
Definitions
- This disclosure relates to carbon nanofibers having novel and advantageous properties. This disclosure also relates to methods of manufacturing such carbon nanofibers.
- Carbon is among a few elements having a high level of chemical bonding flexibility. This flexibility lends itself to the formation of a large variety of allotropes including diamond, graphite, and fullerenes which, while all being composed essentially of elemental carbon, vary widely in their properties.
- One particular relevant field of interest is the formation of Carbon NanoFibers (CNFs) and Carbon NanoTubes (CNTs). While CNFs and CNTs are both nanometer in scale and produced in similar manners, there are distinct differences that impact their manufacturability and chemical and physical properties. However, the complete range of different CNT and CNF materials has not been fully explored.
- FIG. 1 is a flowchart outlining an exemplary operation for manufacturing a novel Carbon NanoFiber (CNF).
- CNF Carbon NanoFiber
- FIG. 2 depicts an example of an electro-spinning device usable to produce the novel CNF discussed with respect to FIG. 1 .
- FIG. 3 depicts a variant of the electro-spinning device of FIG. 2 , which is also usable to produce the novel CNF discussed with respect to FIG. 1 .
- FIGS. 4A-4K depict various electrode configurations for the electrodes shown in FIG. 3 .
- FIG. 5 provides visual representations of the novel CNFs produced by the methods and systems of this disclosure.
- FIG. 6 provides a visual contrast of the novel CNFs produced by the methods and systems of this disclosure against other carbon-based materials.
- FIG. 7 provides series of visual representations of the novel CNFs produced by the methods and systems of this disclosure from the macro-scale to an atomic scale.
- the term “appreciable” refers to some quality, e.g., a particular amount or percentage, of something that results in a detectable difference either from a defined base-line or over prior-art materials. Such quality should be detectable either directly through observation, e.g., through a Scanning Electron Microscope (SEM) or a Transmission electron microscope (TEM), or indirectly through physically and/or chemically detectable properties, e.g., electron mobility, conductivity, etc.
- SEM Scanning Electron Microscope
- TEM Transmission electron microscope
- SAPC Stress Activated Pyrolytic Carbon
- SAPC Stress Activated Pyrolytic Carbon
- SAPC refers to the novel composition based on carbon and nitrogen that is the subject of this disclosure.
- SAPC by the definition of this disclosure, refers to an inclusion of a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1 nm and oriented parallel to an axis of a respective carbon nanofiber.
- oriented parallel refers to the general direction of a main surface of a particular graphitic plane and takes into account that variations in angle are expected to occur based on the “wavy” physical nature of SAPC.
- the semi-graphitic carbon material of this disclosure is also characterized by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms with the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms.
- various “levels of SAPC quality” may be obtained using variations within the prescribed limits and ranges of the disclosed methods and systems, and that a “level of SAPC quality” as used in this disclosure refers to a minimum combined percentage of quaternary and pyridinic nitrogen groups of the nitrogen heteroatoms.
- one particular “level of SAPC quality” may refer to the combined percentage of quaternary and pyridinic nitrogen groups exceeding 70%
- a second particular “level of SAPC quality” may refer to the combined percentage of quaternary and pyridinic nitrogen groups exceeding 80%
- a third particular “level of SAPC quality” may refer to the combined percentage of quaternary and pyridinic nitrogen groups exceeding 90%.
- the lowest SAPC quality is to be considered an “appreciable,” i.e., detectable, combined percentage of quaternary and pyridinic nitrogen groups. However, the lowest SAPC quality of interest is not expected to be less than 60%.
- FIG. 1 is a flowchart outlining an exemplary operation for manufacturing a novel SAPC-based Carbon NanoFibers (CNFs).
- CNFs Carbon NanoFibers
- the process starts in step S 110 where a precursor solution is prepared.
- the particular precursor solution in the present embodiment is a Polyacrylonitrile (PAN) based precursor solution that includes: (1) PAN having a molecular weight ranging from 100,000 to 500,000, and (2) a suitable solvent having less than 5% water by weight.
- PAN Polyacrylonitrile
- the PAN-based precursor solution of the present example includes 6% to 20% PAN by weight in the solvent. However, in varying embodiments the exact percentage of PAN to solvent may vary beyond the 6% to 20% range used in the present example.
- Possible solvents include, for example, Dimethylsulfoxide (DMSO), Dimethylformamide (DMF) and Propylene Carbonate (PC). However, a combination of any two or more of DMSO, DMF or PC may also be used. Further, other solvents and precursors than those expressly described above may be used at a possible reduction in the quality of end product.
- DMSO Dimethylsulfoxide
- DMF Dimethylformamide
- PC Propylene Carbonate
- Preparing the PAN-based precursor solution includes dissolving the PAN in the solvent via a convective mixing operation at a temperature ranging from 25° C. to 130° C. until the PAN is completely dissolved.
- the PAN-based precursor solution may be mixed for a set time period ranging from, for example, one hour to one week while at the previously-described temperature range.
- step S 120 the PAN-based precursor solution is provided to a spinneret, and in step S 130 an electro-spinning operation is performed on the PAN-based precursor solution to create one or more PAN-based fibers.
- the electro-spinning device includes a precursor container 210 , a pump 212 , a Direct Current (DC) voltage source 220 , an Alternating Current (AC) voltage source 222 , an enclosure 230 and an external drum 252 .
- the enclosure 230 has disposed within a spinneret 240 and a collector drum 250 surrounded by an atmosphere 232 .
- the example spinneret 240 of FIG. 2 is a needleless (i.e., nozzle) device. While needleless spinnerets can take many forms, needleless spinnerets are often categorized into two forms: stationary and rotating. For example, in one embodiment, a needleless spinneret can take the form of a stationery conductive metal string. In other embodiments, needless spinnerets can take the form of a drum or drum-like object that rotate inside a bath of precursor solution.
- any number of needle-type spinnerets may be used, such as a single needle spinneret, a multiple needle spinneret, and so on.
- Many needle spinnerets are described as “straw-like” while other needle spinnerets are described as “coaxial.”
- Coaxial spinnerets can produce “core and shell” fibers or even fibers with multiple shells.
- spinneret can include future-developed needle devices, future-developed needless devices and any other known or later developed type of spinneret that does not conveniently fit within the characterizations of “needle” or “needleless.”
- spinneret can include future-developed needle devices, future-developed needless devices and any other known or later developed type of spinneret that does not conveniently fit within the characterizations of “needle” or “needleless.”
- the pump 212 provides the PAN-based precursor from the precursor container 210 to the spinneret 240 .
- the spinneret 240 ejects a plurality of fiber streams 260 to the collector drum 250 , and it is at this time that the PAN-based precursor is processed to form PAN-based fibers 262 .
- the resulting combined PAN-based fibers 262 are then passed to the external drum 252 for collection and storage. While the example spinneret 240 is generally circular and the example collector 250 is drum-shaped, it is to be appreciated that the particular configuration of the spinneret 240 and the collector 250 may vary as is known to those skilled in the relevant arts.
- the distance between the spinneret 240 and the collector drum 250 may vary substantially to include distances ranging from 1 cm to 30 cm, and in other embodiments the distance between the spinneret 240 and the collector drum 250 may exceed 30 cm.
- the DC voltage source 220 and the AC voltage source each provide a differential voltage between the spinneret 240 to the collector drum 250 in such a way as to materially alter the resultant PAN-based fibers 262 .
- the streams of PAN-based precursor are drawn to the collector 250 while being processed.
- the physical dimensions and shape of the resultant PAN-based fibers 262 may be affected so as to produce PAN-based fibers having reduced dimensions. Details regarding an example application of a DC voltage used in an electro-spinning operation may be found in, for example, Ghazinejad, Holmberg et al, “Graphitizing Non-graphitizable Carbons by Stress-induced Routes” published Nov. 29, 2017, by Nature.com (www.Nature.com/scientificreports), the content of which is incorporated by reference in its entirety.
- the AC voltage will include one or more signals each having: (1) a base frequency ranging from 20 Hz to 100,000 Hz, and (2) either a Peak-to-Peak (P-P) voltage ranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to 30,000 V.
- P-P Peak-to-Peak
- RMS Root-Mean-Square
- the one or more voltage signals may be any of a variety of AC signal types, such as a sine wave, a square wave, a triangle wave or combinations thereof.
- the AC voltage provided may not be strictly periodic but may consist of, or include, a random signal, a pseudo-random signal or a signal that appears as white noise or filtered (pink) noise.
- the atmosphere 232 within the container 230 where the electro-spinning operation (e.g., step S 120 ) is performed contains a vapor of the precursor solution solvent at a temperature ranging from 10° C. to 100° C. with a saturation larger than 10%.
- the minimum saturation may exceed 45% at an ambient (sea level) atmosphere.
- a post-electro-spinning operation S 130 is performed on the resultant PAN-based fibers.
- the post-electro-spinning operation S 130 will include both a mechanical treatment and a chemical treatment.
- the mechanical treatment of the post-electro-spinning operation S 130 includes hot-rolling and hot-drawing.
- the hot-rolling treatment is designed to mechanically compress the resultant PAN-based fibers at a stress ranging from 20 kPa to 2000 kPa while at temperature ranging from 50° C. to 300° C.
- the temperature and/or the stress applied may extend beyond their respective cited ranges although the quality of the end product may differ.
- the hot-drawing treatment is designed to stretch the one or more fibers from 5% to 50% of an original length of the resultant PAN-based fibers. However, as with hot-rolling treatment, the amount of stretching may exceed the cited range.
- the chemical treatment of the post-electro-spinning operation includes dipping the resultant PAN-based fibers in a 5% to 30% hydrogen peroxide solution followed by removing any remaining solvent and/or any remaining hydrogen peroxide from the resultant PAN-based fibers.
- any chemical treatment suitable to appropriately clean the resultant PAN-based fibers is envisioned.
- a stabilizing treatment S 140 on the PAN-based fibers which generally involves heating the PAN-based fibers, is performed.
- the stabilizing treatment S 140 may be performed during or after the mechanical treatment of step 130 .
- the stabilizing treatment S 140 will include heating the PAN-based fibers at a temperature ranging from 200° C. to 300° C. while performing the mechanical treatment.
- the stabilizing treatment S 140 will include heating the one or more PAN-based fibers at a temperature ranging from 200° C. to 400° C.
- a pyrolysis treatment S 150 on the PAN-based fibers is performed.
- the pyrolysis treatment S 150 will include heating the PAN fibers in an inert atmosphere containing less than one-percent (1%) oxygen, and will include three separate operations.
- the first operation of step S 150 involves a heating of the PAN-based fibers that takes place in an inert atmosphere, preferably an oxygen-free atmosphere, but generally an atmosphere where oxygen does not exceed one percent.
- temperature will be maintained between 200° C. to 400° C. for a time ranging from one hour to five hours.
- the second operation of step S 150 also involves a heating of the PAN-based fibers in an inert atmosphere. During the second operation, temperature will be maintained between 600° C. to 2000° C. for a time ranging from one hour to five hours.
- the third operation of step S 150 is a cooling operation where temperature is slowly decreased to room temperature.
- the temperature ramp rate should not exceed 20° C./minute.
- the combined percentage of quaternary and pyridinic nitrogen groups will be affected by at least: (1) the choice and/or exact composition of polymer precursor, the AC signal of the electro-spinning operation and the particular pyrolysis treatment used. Accordingly, appropriate choices within the disclosed ranges will cause the combined percentage of quaternary and pyridinic nitrogen groups to exceed, for example, 70%, 80% and even 90%.
- FIG. 3 depicts a variant of the electro-spinning device of FIG. 2 , which is also usable to produce the novel CNFs of this disclosure.
- the AC voltage source 222 instead of providing an AC voltage between the spinneret 240 and the collector drum 250 , the AC voltage source 222 is used to develop an electric field laterally across the fiber streams 260 .
- a channel 320 is formed between electrode 321 and electrode 322 . Accordingly, as the AC voltage source provides an AC electric field between the electrodes ⁇ 320 , 321 ⁇ , the fiber streams 260 will be affected by the AC electric field as the resultant PAN-based fibers 262 are produced.
- FIG. 4A depicts a view of channel 320 along the length of the channel 320 so as to provide a profile of electrode shape.
- the electrodes ⁇ 321 , 322 ⁇ of FIG. 3 are plate-shaped.
- the electrodes ⁇ 321 , 322 ⁇ of FIG. 3 may be substituted with electrodes ⁇ 323 , 324 ⁇ , which are curved to form concave arcs towards the channel 320 .
- the electrodes ⁇ 325 , 326 ⁇ of FIG. 4C may be used, which are curved to form convex arcs towards the channel 320
- the round wire electrodes ⁇ 327 , 328 ⁇ of FIG. 4D may be used.
- FIG. 4E-4K it is to be appreciated that more than two electrodes may be used including the plate-shaped electrodes ⁇ 441 , 442 , 443 ⁇ , ⁇ 444 , 445 , 446 , 447 ⁇ of FIGS. 4E-4F , the concave-shaped electrodes ⁇ 451 , 452 , 453 ⁇ , ⁇ 454 , 455 , 456 , 457 ⁇ of FIGS. 4G-4H , and the convex-shaped electrodes ⁇ 461 , 462 , 463 ⁇ , ⁇ 464 , 465 , 466 , 477 ⁇ of FIGS. 4J-4K .
- an electric field may be generated that does not oscillate back and forth, but rotates about the center axis of the channel 320 .
- one or more rotating fields may be used independently or in combination with one or more alternating fields.
- FIG. 5 depicts an atomic view of SAPC-based carbon fibers. As shown in view 510 of FIG. 5 , a microscopic view of a mass of SAPC-based carbon nanofibers produced by the disclosed methods and devices is provided.
- TEM Transmission Electron Microscope
- the exemplary CNF includes a semi-graphitic carbon material characterized by wavy graphite planes that are generally oriented parallel to an axis of the exemplary carbon nanofiber.
- XPS X-ray Photoelectron Spectroscopy
- FIG. 6 provides comparative views of SAPC against other forms of carbon.
- SAPC from a given fiber is shown next to CNTs embedded in the same fiber.
- CNTs may be made from a similar process as SAPC.
- the substantive differences not only provide CNTs with a different chemistry than SAPC, but also cause the CNT fringes to have a “bamboo” shape.
- an amorphous carbon composition i.e., carbon nitrides
- Carbon nitrides are similar to carbon black but include nitrogen groups instead of oxygen.
- Carbon nitrides come in powder form and, as can be seen in view 620 , carbon nitride planes are not oriented in any particular direction.
- FIG. 7 shows five different views of SAPC.
- the first view (view 710 ) is an optical image of a mat of SAPC fibers held by a pair of tweezers.
- the second view (view 720 ) shows a microscopic view of individual SAPC nanofibers taken from the mat of SAPC nanofibers of view 710 .
- the third view (view 730 ) is another atomic view of an individual SAPC nanofiber taken using a TEM process.
- view 740 shows an exemplary structure of several layers of SAPC with view 750 providing an exemplary molecular structure of a particular molecule/layer consistent with the above-described structure of SAPC.
- the redox species used to measure the electrochemical response in the example of view 750 is ferricyanide.
- any particular redox species, and other redox species, for example, dopamine and iridium hexachloride, can be used.
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Abstract
A method of producing carbon nanofibers is disclosed that substantially impacts the carbon nanofibers' chemical and physical properties. Such carbon nanofibers include a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1 nm and oriented parallel to an axis of a respective carbon nanofiber, the semi-graphitic carbon material also being characterized by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms, the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms. The method of manufacture includes, for example, preparing a Polyacrylonitrile (PAN) based precursor solution, providing the PAN-based precursor solution to a spinneret and then performing an electro-spinning operation on the PAN-based precursor solution to create the one or more PAN-based nanofibers. The electro-spinning operation includes passing the PAN-based precursor solution from the spinneret to a collector at a distance between 1 cm to 30 cm while providing an Alternating Current (AC) voltage between the spinneret and the collector, the AC voltage including a frequency ranging from 20 Hz to 100,000 Hz and either a Peak-to-Peak (P-P) voltage ranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to 30,000 V. Afterwards, post-electro-spinning operations, stabilizing treatments and pyrolysis treatments are performed.
Description
- This disclosure relates to carbon nanofibers having novel and advantageous properties. This disclosure also relates to methods of manufacturing such carbon nanofibers.
- Carbon is among a few elements having a high level of chemical bonding flexibility. This flexibility lends itself to the formation of a large variety of allotropes including diamond, graphite, and fullerenes which, while all being composed essentially of elemental carbon, vary widely in their properties. One particular relevant field of interest is the formation of Carbon NanoFibers (CNFs) and Carbon NanoTubes (CNTs). While CNFs and CNTs are both nanometer in scale and produced in similar manners, there are distinct differences that impact their manufacturability and chemical and physical properties. However, the complete range of different CNT and CNF materials has not been fully explored.
- The features and nature of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the accompanying drawings in which reference characteristics identify corresponding items.
-
FIG. 1 is a flowchart outlining an exemplary operation for manufacturing a novel Carbon NanoFiber (CNF). -
FIG. 2 depicts an example of an electro-spinning device usable to produce the novel CNF discussed with respect toFIG. 1 . -
FIG. 3 depicts a variant of the electro-spinning device ofFIG. 2 , which is also usable to produce the novel CNF discussed with respect toFIG. 1 . -
FIGS. 4A-4K depict various electrode configurations for the electrodes shown inFIG. 3 . -
FIG. 5 provides visual representations of the novel CNFs produced by the methods and systems of this disclosure. -
FIG. 6 provides a visual contrast of the novel CNFs produced by the methods and systems of this disclosure against other carbon-based materials. -
FIG. 7 provides series of visual representations of the novel CNFs produced by the methods and systems of this disclosure from the macro-scale to an atomic scale. - The disclosed methods and systems below may be described generally, as well as in terms of specific examples and/or specific embodiments. For instances where references are made to detailed examples and/or embodiments, it should be appreciated that any of the underlying principals described are not to be limited to a single embodiment, but may be expanded for use with any of the other methods and systems described herein as will be understood by one of ordinary skill in the art unless otherwise stated specifically.
- The following special definitions apply for this disclosure.
- The term “appreciable” refers to some quality, e.g., a particular amount or percentage, of something that results in a detectable difference either from a defined base-line or over prior-art materials. Such quality should be detectable either directly through observation, e.g., through a Scanning Electron Microscope (SEM) or a Transmission electron microscope (TEM), or indirectly through physically and/or chemically detectable properties, e.g., electron mobility, conductivity, etc.
- The term “about” refers to variations expected in industrial manufacturing equipment for CNFs that may vary for different forms of equipment. For example, it is expected that even the most expensive high-voltage equipment will likely produce voltage outputs that vary a few percent.
- The term “about” also refers to variations in an end product that are expected to occur even when reasonable quality controls are employed.
- The term “Stress Activated Pyrolytic Carbon,” or “SAPC,” refers to the novel composition based on carbon and nitrogen that is the subject of this disclosure. SAPC, by the definition of this disclosure, refers to an inclusion of a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1 nm and oriented parallel to an axis of a respective carbon nanofiber. The term “oriented parallel” refers to the general direction of a main surface of a particular graphitic plane and takes into account that variations in angle are expected to occur based on the “wavy” physical nature of SAPC.
- The semi-graphitic carbon material of this disclosure is also characterized by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms with the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms. However, it is to be appreciated that various “levels of SAPC quality” may be obtained using variations within the prescribed limits and ranges of the disclosed methods and systems, and that a “level of SAPC quality” as used in this disclosure refers to a minimum combined percentage of quaternary and pyridinic nitrogen groups of the nitrogen heteroatoms.
- For example, one particular “level of SAPC quality” may refer to the combined percentage of quaternary and pyridinic nitrogen groups exceeding 70%, a second particular “level of SAPC quality” may refer to the combined percentage of quaternary and pyridinic nitrogen groups exceeding 80%, and a third particular “level of SAPC quality” may refer to the combined percentage of quaternary and pyridinic nitrogen groups exceeding 90%.
- The lowest SAPC quality is to be considered an “appreciable,” i.e., detectable, combined percentage of quaternary and pyridinic nitrogen groups. However, the lowest SAPC quality of interest is not expected to be less than 60%.
- Testing by the inventors of the disclosed method and systems indicates that the uppermost range of SAPC quality according to the presently-disclosed methods and systems exceeds 90%.
-
FIG. 1 is a flowchart outlining an exemplary operation for manufacturing a novel SAPC-based Carbon NanoFibers (CNFs). - The process starts in step S110 where a precursor solution is prepared. The particular precursor solution in the present embodiment is a Polyacrylonitrile (PAN) based precursor solution that includes: (1) PAN having a molecular weight ranging from 100,000 to 500,000, and (2) a suitable solvent having less than 5% water by weight.
- The PAN-based precursor solution of the present example includes 6% to 20% PAN by weight in the solvent. However, in varying embodiments the exact percentage of PAN to solvent may vary beyond the 6% to 20% range used in the present example.
- Possible solvents include, for example, Dimethylsulfoxide (DMSO), Dimethylformamide (DMF) and Propylene Carbonate (PC). However, a combination of any two or more of DMSO, DMF or PC may also be used. Further, other solvents and precursors than those expressly described above may be used at a possible reduction in the quality of end product.
- Preparing the PAN-based precursor solution includes dissolving the PAN in the solvent via a convective mixing operation at a temperature ranging from 25° C. to 130° C. until the PAN is completely dissolved. Alternatively, the PAN-based precursor solution may be mixed for a set time period ranging from, for example, one hour to one week while at the previously-described temperature range.
- Next, in step S120, the PAN-based precursor solution is provided to a spinneret, and in step S130 an electro-spinning operation is performed on the PAN-based precursor solution to create one or more PAN-based fibers.
- Referring to
FIG. 2 , an example of an electro-spinning device usable to produce the SAPC-based CNFs is disclosed. The electro-spinning device includes aprecursor container 210, apump 212, a Direct Current (DC)voltage source 220, an Alternating Current (AC)voltage source 222, anenclosure 230 and anexternal drum 252. Theenclosure 230 has disposed within a spinneret 240 and acollector drum 250 surrounded by anatmosphere 232. - The example spinneret 240 of
FIG. 2 is a needleless (i.e., nozzle) device. While needleless spinnerets can take many forms, needleless spinnerets are often categorized into two forms: stationary and rotating. For example, in one embodiment, a needleless spinneret can take the form of a stationery conductive metal string. In other embodiments, needless spinnerets can take the form of a drum or drum-like object that rotate inside a bath of precursor solution. - While the example spinneret 240 of
FIG. 2 is needleless, in still other embodiments any number of needle-type spinnerets may be used, such as a single needle spinneret, a multiple needle spinneret, and so on. Many needle spinnerets are described as “straw-like” while other needle spinnerets are described as “coaxial.” Coaxial spinnerets can produce “core and shell” fibers or even fibers with multiple shells. - In addition to known needle and needless devices, it is envisioned that the term “spinneret” can include future-developed needle devices, future-developed needless devices and any other known or later developed type of spinneret that does not conveniently fit within the characterizations of “needle” or “needleless.” By way of example, by providing an atomized mist of the PAN-precursor into a volume of space and then “blasting” the individual PAN-precursor particles constituting the mist towards a collector using an appropriate gas or vapor, it is possible to produce a number fine fibers.
- In operation, the
pump 212 provides the PAN-based precursor from theprecursor container 210 to thespinneret 240. The spinneret 240, in turn, ejects a plurality offiber streams 260 to thecollector drum 250, and it is at this time that the PAN-based precursor is processed to form PAN-basedfibers 262. The resulting combinedPAN-based fibers 262 are then passed to theexternal drum 252 for collection and storage. While the example spinneret 240 is generally circular and theexample collector 250 is drum-shaped, it is to be appreciated that the particular configuration of thespinneret 240 and thecollector 250 may vary as is known to those skilled in the relevant arts. - Within the operation of the embodiment of
FIGS. 1-2 , the distance between thespinneret 240 and thecollector drum 250 may vary substantially to include distances ranging from 1 cm to 30 cm, and in other embodiments the distance between thespinneret 240 and thecollector drum 250 may exceed 30 cm. - As the fiber streams 260 are passed from the
spinneret 240 to thecollector drum 250, theDC voltage source 220 and the AC voltage source each provide a differential voltage between thespinneret 240 to thecollector drum 250 in such a way as to materially alter the resultantPAN-based fibers 262. - For example, by providing a DC voltage ranging from about plus or minus 1000 V to about plus or minus 30,000 V between the
spinneret 240 and thecollector 250 while passing the fiber streams 260, the streams of PAN-based precursor are drawn to thecollector 250 while being processed. In addition, the physical dimensions and shape of the resultantPAN-based fibers 262 may be affected so as to produce PAN-based fibers having reduced dimensions. Details regarding an example application of a DC voltage used in an electro-spinning operation may be found in, for example, Ghazinejad, Holmberg et al, “Graphitizing Non-graphitizable Carbons by Stress-induced Routes” published Nov. 29, 2017, by Nature.com (www.Nature.com/scientificreports), the content of which is incorporated by reference in its entirety. - Further, by providing an appropriate AC voltage between the
spinneret 240 and thecollector drum 250, the physical and chemical properties unique to SAPC are enabled. In various embodiments, the AC voltage will include one or more signals each having: (1) a base frequency ranging from 20 Hz to 100,000 Hz, and (2) either a Peak-to-Peak (P-P) voltage ranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to 30,000 V. - Also in various embodiments, the one or more voltage signals may be any of a variety of AC signal types, such as a sine wave, a square wave, a triangle wave or combinations thereof.
- In other embodiments, however, the AC voltage provided may not be strictly periodic but may consist of, or include, a random signal, a pseudo-random signal or a signal that appears as white noise or filtered (pink) noise.
- Returning to
FIG. 2 , theatmosphere 232 within thecontainer 230 where the electro-spinning operation (e.g., step S120) is performed contains a vapor of the precursor solution solvent at a temperature ranging from 10° C. to 100° C. with a saturation larger than 10%. However, in various embodiments the minimum saturation may exceed 45% at an ambient (sea level) atmosphere. - Returning to
FIG. 1 , after the electro-spinning operation ofstep 120, a post-electro-spinning operation S130 is performed on the resultant PAN-based fibers. According to the present disclosure, the post-electro-spinning operation S130 will include both a mechanical treatment and a chemical treatment. - The mechanical treatment of the post-electro-spinning operation S130 includes hot-rolling and hot-drawing.
- The hot-rolling treatment is designed to mechanically compress the resultant PAN-based fibers at a stress ranging from 20 kPa to 2000 kPa while at temperature ranging from 50° C. to 300° C. However, in other embodiments the temperature and/or the stress applied may extend beyond their respective cited ranges although the quality of the end product may differ.
- The hot-drawing treatment is designed to stretch the one or more fibers from 5% to 50% of an original length of the resultant PAN-based fibers. However, as with hot-rolling treatment, the amount of stretching may exceed the cited range.
- The chemical treatment of the post-electro-spinning operation includes dipping the resultant PAN-based fibers in a 5% to 30% hydrogen peroxide solution followed by removing any remaining solvent and/or any remaining hydrogen peroxide from the resultant PAN-based fibers. However, any chemical treatment suitable to appropriately clean the resultant PAN-based fibers is envisioned.
- Continuing, a stabilizing treatment S140 on the PAN-based fibers, which generally involves heating the PAN-based fibers, is performed. The stabilizing treatment S140 may be performed during or after the mechanical treatment of
step 130. - If the stabilizing treatment S140 is performed during the mechanical treatment, the stabilizing treatment S140 will include heating the PAN-based fibers at a temperature ranging from 200° C. to 300° C. while performing the mechanical treatment.
- If the stabilizing treatment S140 is performed after the mechanical treatment, the stabilizing treatment S140 will include heating the one or more PAN-based fibers at a temperature ranging from 200° C. to 400° C.
- After performing the post-electro-spinning operation and stabilizing treatment of steps S130 and S140, a pyrolysis treatment S150 on the PAN-based fibers is performed. Generally, the pyrolysis treatment S150 will include heating the PAN fibers in an inert atmosphere containing less than one-percent (1%) oxygen, and will include three separate operations.
- The first operation of step S150 involves a heating of the PAN-based fibers that takes place in an inert atmosphere, preferably an oxygen-free atmosphere, but generally an atmosphere where oxygen does not exceed one percent. During the first operation, temperature will be maintained between 200° C. to 400° C. for a time ranging from one hour to five hours.
- The second operation of step S150 also involves a heating of the PAN-based fibers in an inert atmosphere. During the second operation, temperature will be maintained between 600° C. to 2000° C. for a time ranging from one hour to five hours.
- The third operation of step S150 is a cooling operation where temperature is slowly decreased to room temperature.
- It is to be appreciated that, for all three operations of the pyrolysis treatment S150, the temperature ramp rate should not exceed 20° C./minute.
- In view of the discussion above, it should be appreciated that the combined percentage of quaternary and pyridinic nitrogen groups will be affected by at least: (1) the choice and/or exact composition of polymer precursor, the AC signal of the electro-spinning operation and the particular pyrolysis treatment used. Accordingly, appropriate choices within the disclosed ranges will cause the combined percentage of quaternary and pyridinic nitrogen groups to exceed, for example, 70%, 80% and even 90%.
-
FIG. 3 depicts a variant of the electro-spinning device ofFIG. 2 , which is also usable to produce the novel CNFs of this disclosure. In the embodiment ofFIG. 3 , instead of providing an AC voltage between thespinneret 240 and thecollector drum 250, theAC voltage source 222 is used to develop an electric field laterally across the fiber streams 260. As shown inFIG. 3 , achannel 320 is formed betweenelectrode 321 andelectrode 322. Accordingly, as the AC voltage source provides an AC electric field between the electrodes {320, 321}, the fiber streams 260 will be affected by the AC electric field as the resultantPAN-based fibers 262 are produced. -
FIG. 4A depicts a view ofchannel 320 along the length of thechannel 320 so as to provide a profile of electrode shape. As shown inFIG. 4A , the electrodes {321, 322} ofFIG. 3 are plate-shaped. However, as shown inFIG. 4B , the electrodes {321, 322} ofFIG. 3 may be substituted with electrodes {323, 324}, which are curved to form concave arcs towards thechannel 320. Similarly, the electrodes {325, 326} ofFIG. 4C may be used, which are curved to form convex arcs towards thechannel 320, and as another variant the round wire electrodes {327, 328} ofFIG. 4D may be used. - Turning to
FIG. 4E-4K , it is to be appreciated that more than two electrodes may be used including the plate-shaped electrodes {441, 442, 443}, {444, 445, 446, 447} ofFIGS. 4E-4F , the concave-shaped electrodes {451, 452, 453}, {454, 455, 456, 457} ofFIGS. 4G-4H , and the convex-shaped electrodes {461, 462, 463}, {464, 465, 466, 477} ofFIGS. 4J-4K . - It should be appreciated that, by using three or four electrodes of various configurations, an electric field may be generated that does not oscillate back and forth, but rotates about the center axis of the
channel 320. Additionally, one or more rotating fields may be used independently or in combination with one or more alternating fields. - For example, by using the four electrodes {444, 445, 446, 447} of
FIG. 4F , it is possible to produce a clockwise rotating electric field that rotates aboutchannel 320 at a rate of 20,000 Hz, a counter-clockwise rotating electric field that rotates aboutchannel 320 at a rate of 51,000 Hz, a first oscillating electric field that oscillates between electrodes {444, 446} at a rate of 150,000 Hz, and a second oscillating electric field that oscillates between electrodes {445, 447} at a rate of 210,000 Hz. -
FIG. 5 depicts an atomic view of SAPC-based carbon fibers. As shown inview 510 ofFIG. 5 , a microscopic view of a mass of SAPC-based carbon nanofibers produced by the disclosed methods and devices is provided. - In contrast to view 510, in view 520 a Transmission Electron Microscope (TEM) image of SAPC for an exemplary CNF is provided. As shown in
view 520, the exemplary CNF includes a semi-graphitic carbon material characterized by wavy graphite planes that are generally oriented parallel to an axis of the exemplary carbon nanofiber. While not shown inFIG. 5 , X-ray Photoelectron Spectroscopy (XPS) confirms the presence of graphitic and pyridinic nitrogen groups, which grants SAPC with unique electrocatalysis orders of magnitude greater than similar materials. -
FIG. 6 provides comparative views of SAPC against other forms of carbon. As shown inview 610, SAPC from a given fiber is shown next to CNTs embedded in the same fiber. CNTs may be made from a similar process as SAPC. However, the substantive differences not only provide CNTs with a different chemistry than SAPC, but also cause the CNT fringes to have a “bamboo” shape. - Continuing, as shown in
view 620, an amorphous carbon composition, i.e., carbon nitrides, is provided. Carbon nitrides are similar to carbon black but include nitrogen groups instead of oxygen. Carbon nitrides come in powder form and, as can be seen inview 620, carbon nitride planes are not oriented in any particular direction. -
FIG. 7 shows five different views of SAPC. The first view (view 710) is an optical image of a mat of SAPC fibers held by a pair of tweezers. The second view (view 720) shows a microscopic view of individual SAPC nanofibers taken from the mat of SAPC nanofibers ofview 710. The third view (view 730) is another atomic view of an individual SAPC nanofiber taken using a TEM process. - Continuing, view 740 shows an exemplary structure of several layers of SAPC with
view 750 providing an exemplary molecular structure of a particular molecule/layer consistent with the above-described structure of SAPC. The redox species used to measure the electrochemical response in the example ofview 750 is ferricyanide. However, any particular redox species, and other redox species, for example, dopamine and iridium hexachloride, can be used. - What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
Claims (20)
1. A method of producing one or more carbon nanofibers, the carbon nanofibers including a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1 nm and oriented parallel to an axis of a respective carbon nanofiber, the semi-graphitic carbon material also being characterized by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms, the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms, the method comprising:
preparing a Polyacrylonitrile (PAN) based precursor solution;
providing the PAN-based precursor solution to a spinneret;
performing an electro-spinning operation on the PAN-based precursor solution followed by pyrolysis of the PAN-based fibers to create the one or more carbon nanofibers, wherein the electro-spinning operation includes passing the PAN-based precursor solution from the spinneret to a collector at a distance between 1 cm to 30 cm while providing an Alternating Current (AC) voltage between the spinneret and the collector, the AC voltage including a frequency ranging from 20 Hz to 100,000 Hz and either a Peak-to-Peak (P-P) voltage ranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to 30,000 V;
performing a post-electro-spinning operation on the one or more carbon nanofibers, the post-electro-spinning operation including a mechanical treatment and a chemical treatment;
performing a stabilizing treatment on the one or more PAN-based nanofibers, the stabilizing treatment including heating the one or more PAN-based nanofibers; and
after performing the post-electro-spinning operation and stabilizing treatment, performing a pyrolysis treatment on the one or more PAN-based nanofibers, the pyrolysis treatment including heating the one or more PAN-based nanofibers in an inert atmosphere containing less than 1% oxygen.
2. The method of claim 1 , wherein the electro-spinning operation further includes providing a Direct Current (DC) voltage between the spinneret and the collector at a distance between 1 cm to 30 cm while passing the PAN-based precursor solution from the spinneret to the collector, the DC voltage ranging from about plus or minus 100 V to about plus or minus 30,000 V.
3. The method of claim 2 , wherein the electro-spinning operation is performed in an atmosphere containing vapor of the precursor solution solvent at a temperature ranging from 10° C. to 100° C. with a saturation larger than 10%.
4. The method of claim 3 , wherein the electro-spinning operation is performed in an ambient atmosphere at a temperature ranging from 10° C. to 100° C. with minimum saturation of 45%.
5. The method of claim 1 , wherein the PAN-based precursor solution includes 6% to 20% PAN by weight in a solvent.
6. The method of claim 5 , wherein the solvent includes at least one of Dimethylsulfoxide (DMSO) Dimethylformamide (DMF), Propylene Carbonate (PC) and a combination of any or all of DMSO, DMF or PC, and wherein the solvent has less than 5% water by weight.
7. The method of claim 5 , wherein preparing the PAN-based precursor solution includes dissolving the PAN in the solvent via a convective mixing operation at a temperature ranging from 25° C. to 130° C. until the PAN is completely dissolved or for 1 hour to 1 week, wherein the PAN has a molecular weight ranging from 100,000 to 500,000.
8. The method of claim 1 , wherein
the mechanical treatment of the post-electro-spinning operation includes one or both of hot-rolling and/or hot-drawing; and
the chemical treatment of the post-electro-spinning operation includes dipping the one or more carbon nanofibers in a 5% to 30% hydrogen peroxide solution followed by removing any remaining solvent and/or any remaining hydrogen peroxide from the one or more carbon nanofibers.
9. The method of claim 8 , wherein
the hot-rolling mechanically compresses the one or more PAN-based nanofibers at temperature ranging from 50° C. to 300° C. and a stress ranging from 20 kPa to 2000 kPa; and
the hot-drawing stretches the one or more carbon nanofibers 5%-50% of an original length of the one or more PAN-based nanofibers.
10. The method of claim 8 , wherein the stabilizing treatment includes heating the one or more PAN-based nanofibers at a temperature ranging from 200° C. to 300° C. while performing the mechanical treatment.
11. The method of claim 1 , wherein the stabilizing treatment includes heating the one or more PAN-based nanofibers at a temperature ranging from 200° C. to 400° C.
12. The method of claim 1 , wherein the pyrolysis treatment includes:
performing first heating operation of the one or more PAN-based nanofibers in the inert atmosphere at temperature between 200° C. to 400° C. for a time ranging from 1 hour to five hours;
after the first heating operation, performing a second heating operation of the one or more PAN-based nanofibers in the inert atmosphere at temperature between 600° C. to 2000° C. for a time ranging from 1 hour to five hours; and
after the second heating operation, performing a cooling operation on the one or more carbonized PAN-based nanofibers to room temperature;
wherein a temperature ramp rate for each operation of the pyrolysis treatment does not exceed 20° C./minute.
13. The method of claim 1 , wherein the choice of polymer precursor, the electro-spinning operation and the pyrolysis treatment is sufficient to cause the combined percentage of quaternary and pyridinic nitrogen groups to exceed 80%.
14. The method of claim 13 , wherein the choice of polymer precursor, the electro-spinning operation and the pyrolysis treatment is sufficient to cause the combined percentage of quaternary and pyridinic nitrogen groups to exceed 90%.
15. A carbon-based composition; comprising:
one or more carbon nanofibers that include a carbon composite, wherein
the carbon composite is a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1.0 nm and having fringes oriented parallel to an axis of a respective carbon nanofiber, and the semi-graphitic carbon material is also characterized by an inclusion of by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms, the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms.
16. The carbon-based composition of claim 15 , wherein the combined percentage of quaternary and pyridinic nitrogen groups of the nitrogen heteroatoms exceeds 80%.
17. The carbon-based composition of claim 16 , wherein the combined percentage of quaternary and pyridinic nitrogen groups of the nitrogen heteroatoms exceeds 90%.
18. A carbon-based composition of one or more carbon nanofibers that include a carbon composite, wherein the carbon composite is a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1.0 nm and oriented parallel to an axis of a respective carbon nanofiber, the semi-graphitic carbon material also being characterized by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms with the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms, wherein the carbon-based composition is prepared by a process comprising the steps of:
preparing a Polyacrylonitrile (PAN) based precursor solution;
providing the PAN-based precursor solution to a spinneret;
performing an electro-spinning operation on the PAN-based precursor solution to create the one or more carbon nanofibers, wherein the electro-spinning operation includes passing the PAN-based precursor solution from the spinneret to a collector while providing an Alternating Current (AC) voltage between the spinneret and the collector, the AC voltage having a frequency ranging from 20 Hz to 100,000 Hz and either a Peak-to-Peak (P-P) voltage ranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to 30,000 V;
performing a post-electro-spinning operation on the one or more carbon nanofibers, the post-electro-spinning operation including a mechanical treatment and a chemical treatment;
performing a stabilizing treatment on the one or more carbon nanofibers, the stabilizing treatment including heating the one or more carbon nanofibers; and
after performing the post-electro-spinning operation and stabilizing treatment, performing a pyrolysis treatment on the one or more carbon nanofibers, the pyrolysis treatment including heating the one or more carbon nanofibers in an inert atmosphere containing less than 1% oxygen.
19. The carbon-based composition of claim 18 , wherein the combined percentage of quaternary and pyridinic nitrogen groups of the nitrogen heteroatoms exceeds 80%.
20. The carbon-based composition of claim 19 , wherein the combined percentage of quaternary and pyridinic nitrogen groups of the nitrogen heteroatoms exceeds 90%.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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US15/998,860 US11180870B2 (en) | 2018-08-17 | 2018-08-17 | Carbon nanofiber and method of manufacture |
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US11180870B2 (en) * | 2018-08-17 | 2021-11-23 | Cence Inc. | Carbon nanofiber and method of manufacture |
CN114606579B (en) * | 2020-12-03 | 2023-08-01 | 吉林碳谷碳纤维股份有限公司 | Ammoniation method and device for polyacrylonitrile spinning solution |
CN112599777B (en) * | 2020-12-14 | 2022-09-27 | 河北工业大学 | Preparation method and application of transition metal sulfide/nitrogen and sulfur co-doped carbon composite fiber electrode material |
CN113113599B (en) * | 2021-04-19 | 2022-08-05 | 四川轻化工大学 | Preparation method and application of nitrogen-doped self-supporting nanofiber membrane |
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US20040092185A1 (en) * | 2002-11-13 | 2004-05-13 | Grafe Timothy H. | Wipe material with nanofiber layer |
JP5350635B2 (en) * | 2004-11-09 | 2013-11-27 | ボード・オブ・リージエンツ,ザ・ユニバーシテイ・オブ・テキサス・システム | Production and application of nanofiber ribbons and sheets and nanofiber twisted and untwisted yarns |
CN100387762C (en) * | 2006-07-10 | 2008-05-14 | 浙江大学 | Polyacrylonitrile mesopore-macropore ultrafine carbon fiber and its preparation method |
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