A carbon nanoribbon and its preparation method and application

Abstract

The present invention discloses a carbon nano ribbon and a preparation method and application thereof, wherein the carbon nano ribbon comprises a first carbon nano ribbon and a second carbon nano ribbon, wherein: the first carbon nano ribbon has P2 / m point group and contains only five-membered carbon rings and seven-membered carbon rings, which are metallic; the second carbon nanoribbon has Pmc2 The present invention provides a method for preparing the carbon nanoribbon, using 1,5-dibromo-1,5-cyclooctadiene as a precursor molecule, and reacting carbon and hydrogen through two elements. sp 2 Hybridization forms a carbon nanobelt having only pure five-membered carbon rings and seven-membered carbon rings. The carbon nanobelt in the present invention does not contain any six-membered carbon rings at all, is a strong metallic carbon nanobelt with good electrical conductivity, and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon material preparation, and in particular relates to a carbon nano-ribbon and a preparation method and application thereof. Background Art

[0002] Graphene Nanoribbons (GNRs) are a kind of carbon nanoribbons. sp 2 The two-dimensional material formed by the hybrid orbital has a single layer of carbon atoms and a width of less than 10nm. Due to its unique structure and properties, this material has important application value in carbon-based optoelectronic devices, sensors, catalysis and other fields.

[0003] At present, the mainstream carbon nanoribbon is graphene nanoribbon. Due to its hexagonal lattice and one-dimensional confinement effect, most graphene nanoribbons show semiconductor properties and can be used in carbon-based devices. Theoretical predictions will sp 2 Hybridized carbon atoms can form bonds in a non-hexagonal manner to achieve a strong metallic nanoribbon structure, which can act as a conductive wire in future carbon-based chips.

[0004] However, there are no reports of strong metallic carbon nanoribbons with good electrical conductivity. In addition, currently, the non-hexagonal carbon rings are embedded in carbon nanoribbons mainly by directly implanting non-hexagonal carbon rings in precursor molecules, which cannot completely remove the hexagonal carbon ring structure in the carbon nanoribbons.

[0005] The present invention is devoted to clarifying a strong metallic carbon nanoribbon that is completely free of hexacyclic carbon rings, so as to promote the development of carbon-based devices, especially carbon-based chips. Summary of the invention

[0006] In view of this, the primary purpose of the present invention is to provide a carbon nanoribbon containing only five-membered carbon rings and seven-membered carbon rings and a preparation method thereof. The carbon nanoribbon does not contain any six-membered carbon rings at all and is a strong metallic carbon nanoribbon with good conductive properties and has broad application prospects.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A first aspect of the present invention provides a carbon nanoribbon, comprising a first carbon nanoribbon and a second carbon nanoribbon, wherein:

[0009] The first carbon nanoribbon has P2 / m The point group contains only five-membered carbon rings and seven-membered carbon rings, which are metallic;

[0010] The second carbon nanoribbon has Pmc2It has a point group of 1 and contains only five-membered carbon rings and seven-membered carbon rings, and is a semiconductor.

[0011] The carbon nanoribbons in the present invention contain only five-membered carbon rings and seven-membered carbon rings, do not contain six-membered carbon rings at all, and have strong metallic properties, so they have broad application prospects.

[0012] The second aspect of the present invention provides a method for preparing the carbon nanoribbons, comprising the following steps:

[0013] Provide 1,5-dibromo-1,5-cyclooctadiene as a precursor molecule, under vacuum pressure less than 5×10 -10 Under the ultra-high vacuum environment of mbar, a coating film is deposited on the substrate surface to form polycyclooctadiene through the Ullmann coupling reaction;

[0014] The polycyclooctadiene is subjected to a dehydrogenation cyclization reaction to generate a polypentene chain;

[0015] The polypentene chain is subjected to a dehydrogenation coupling reaction to form a carbon nanoribbon containing only five-membered carbon rings and seven-membered carbon rings.

[0016] In the present invention, 1,5-dibromo-1,5-cyclooctadiene is used as a precursor molecule, and through Ullmann coupling reaction, dehydrogenation cyclization reaction and dehydrogenation coupling reaction, carbon and hydrogen are reacted to form a cyclopentadiene. sp 2 The hybridization forms the carbon nanoribbons having only five-membered carbon rings and seven-membered carbon rings in the present invention.

[0017] The third aspect of the present invention provides the use of the carbon nanoribbons in the preparation of carbon-based devices.

[0018] A fourth aspect of the present invention provides a carbon-based chip comprising conductive wires, wherein the conductive wires are prepared using the carbon nanoribbons.

[0019] The carbon nanoribbons of the present invention include P2 / m The first carbon nanoribbon with point groups and Pmc2 1 point group and the second carbon nanoribbon, both of which are made of carbon and hydrogen. sp 2 Hybrid formation, in which the first carbon nanoribbon is metallic and the second carbon nanoribbon is semiconductor and contains only five-membered carbon rings and seven-membered carbon rings. Therefore, it has excellent conductive properties and strong metallic properties, and its resistance is small. It can be used in carbon-based devices, especially as a conductive wire in carbon-based chips, which can greatly reduce the heating effect when the chip is running.

[0020] Beneficial effects of the present invention:

[0021] The present invention uses 1,5-dibromo-1,5-cyclooctadiene (DBCOD) as a precursor molecule, and carbon and hydrogen are reacted through sp 2 Hybridization forms a carbon nanoribbon with only pure five-membered carbon rings and seven-membered carbon rings, which includes P2 / m The first carbon nanoribbon with point groups and Pmc2 The second carbon nanoribbon of point group 1 is metallic and semiconductor. Since this carbon nanoribbon has only pure five-carbon rings and seven-membered carbon rings and does not contain any six-membered carbon rings, it is a strong metallic carbon nanoribbon with good electrical conductivity. It can act as a conductive wire in future carbon-based chips. It has low resistance and can greatly reduce the heating effect when the chip is running. It has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a schematic diagram of the process of preparing carbon nanoribbons in a preferred embodiment of the present invention.

[0023] Figure 2 The scanning tunneling microscope (STM) and atomic force microscope (AFM) images of the carbon nanoribbons CPHN 1 and CPHN 2 prepared in Example 2 are shown; wherein, Figure 2 a and Figure 2 b are the STM and AFM images of carbon nanoribbon CPHN 1, Figure 2 c and Figure 2 d are the STM and AFM images of carbon nanoribbons CPHN 2, respectively.

[0024] Figure 3 The electron transport properties of the carbon nanoribbons prepared in Example 2 are characterized as follows: Figure 3 a is a schematic diagram of the construction of a dual-electrode device for transport testing. Figure 3 b is the curve of the conductivity of carbon nanoribbons CPHN 1 and CPHN 2 changing with their length. Figure 3 c and Figure 3 d shows the transport of carbon nanoribbons CPHN 1 and CPHN 2. IV curve. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] A first aspect of the present invention provides a carbon nanoribbon, comprising a first carbon nanoribbon (named CPHN 1 herein) and a second carbon nanoribbon (named CPHN 2 herein), wherein:

[0028] Carbon nanoribbon CPHN 1 has P2 / m The point group contains only five-membered carbon rings and seven-membered carbon rings, which are metallic;

[0029] Carbon nanoribbon CPHN 2 has Pmc2 It has a point group of 1 and contains only five-membered carbon rings and seven-membered carbon rings, and is a semiconductor.

[0030] In the present invention, the term "point group" is a mathematical tool for describing the symmetry of a molecule or crystal, which consists of a set of all symmetry operations on a molecule or crystal. In crystallography, a space group is a symmetry group that includes translation operations, while a point group is a symmetry group that does not include translation operations.

[0031] In the present invention, " P2 / m The "point group" is considered as a subset of the space group P2 / m, considering only its point symmetry; this point group belongs to the monoclinic system, which is characterized by a symmetry operation including a 2-fold rotation axis and a mirror plane perpendicular to the b axis.

[0032] In the present invention, " Pmc2 The "1 point group" belongs to the non-centrosymmetric space group, which does not contain any mirror or rotation inversion operations. Specifically, Pmc2 The point group 1 contains the following symmetry elements: ① a mirror plane (m) parallel to the c-axis; ② a slip plane (c) perpendicular to the c-axis; ③ an anti-axis along the c-axis (2).

[0033] After characterization and calculation, the carbon nanoribbons prepared in the present invention have a carbon nanoribbon CPHN 1 P2 / m Point group, carbon nanoribbon CPHN 2 has Pmc2 1 point group, and both carbon nanoribbons contain only five-membered carbon rings and seven-membered carbon rings, but no six-membered carbon rings at all.

[0034] In this field, metallicity, semiconductors and insulators are generally distinguished based on energy band structure, electron freedom, etc. Specifically, metal conductors have no forbidden bands, and electrons can freely jump between full bands and empty bands, and have strong conductivity; semiconductors have small forbidden band energy, and electrons can easily jump from full bands to empty bands to form conduction bands, and can conduct electricity under certain conditions; while insulators have large forbidden band energy, and electrons cannot jump from full bands to empty bands, and cannot conduct electricity. The carbon nanoribbons in the present invention have been characterized, and it is determined that the carbon nanoribbon CPHN 1 is metallic, while the carbon nanoribbon CPHN 2 is a semiconductor.

[0035] In the present invention, the carbon nanoribbon CPHN 1 and the carbon nanoribbon CPHN 2 are both made of carbon and hydrogen. sp 2 Hybridized.

[0036] Through characterization, it was found that both carbon nanoribbons CPHN 1 and carbon nanoribbons CPHN 2 have planar structures; their thickness is a single carbon atom layer, and their width is 1nm~1.2nm.

[0037] The second aspect of the present invention provides a method for preparing the carbon nanoribbons as described in the first aspect of the present invention, comprising the following steps:

[0038] Provide 1,5-dibromo-1,5-cyclooctadiene (DBCOD) as a precursor molecule, under vacuum pressure below 5×10 - 10 Under the ultra-high vacuum environment of mbar, a coating is deposited on the substrate surface to form polycyclooctadiene (PCOD) through Ullmann coupling reaction;

[0039] The polycyclooctadiene is subjected to a dehydrogenation cyclization reaction to generate a polypentylene chain (PPTL);

[0040] The polypentene chain is subjected to a dehydrogenation coupling reaction to form a carbon nanoribbon containing only five-membered carbon rings and seven-membered carbon rings.

[0041] The specific preparation process can be found in Figure 1 .

[0042] The precursor molecule selected in the present invention is 1,5-dibromo-1,5-cyclooctadiene (DBCOD), and its molecular structure is as follows:

[0043] .

[0044] In the present invention, the precursor molecule 1,5-dibromo-1,5-cyclooctadiene (DBCOD) is prepared by referring to the disclosed method, for details, see van Delft P, de Witte W, Meeuwenoord NJ, et al. Design of a Ribosyltriazole‐Annulated Cyclooctyne for Oligonucleotide Labeling by Strain‐ Promoted Alkyne–Azide Cycloaddition[J]. European Journal of Organic Chemistry, 2014, 2014(34): 7566-7571 .

[0045] The substrate used in the present invention is a silver single crystal (111), that is, the deposition is performed on the (111) crystal plane of the single crystal silver. The deposition method is molecular beam epitaxy. Specifically, under ultra-vacuum conditions, the precursor molecules are deposited on the surface of the silver single crystal (111) at a temperature of 300K~320K, and are catalyzed by the surface of the silver single crystal. The C-Br bond is immediately broken and an Ullmann coupling reaction is performed between the molecules to form polycyclooctadiene (PCOD). Subsequently, under the catalytic action of the silver single crystal (111) surface, the four sp3 The hybridized carbon atoms lose six hydrogen atoms and two of the diagonal carbon atoms undergo CC coupling to form polypentylene chains (PPTL). Finally, under the catalytic action of the silver single crystal (111) surface, each polypentylene unit further loses two hydrogen atoms and undergoes a dehydrogenation coupling reaction with another dehydrogenated pentylene chain to form carbon nanoribbons CPHN 1 and CPHN 2.

[0046] It is understandable that specific deposition conditions, such as temperature, speed and time, can be determined experimentally based on methods known to those skilled in the art. In some specific implementation cases of the present invention, the deposition temperature is 300K~320K, the speed is 0.5nm / h~1.5nm / h, and the time is 5min~10min.

[0047] Ullmann Coupling is generally an organic chemical reaction in which a halogenated aromatic compound and an aromatic nucleophile undergo coupling reaction under the action of a catalyst to form a carbon-carbon bond. In the present invention, a variant of the Ullmann coupling reaction on an ultra-high vacuum solid surface is used. Specifically, the silver single crystal (111) surface is used as a catalyst to catalyze the dissociation of the C-Br bond of the 1,5-dibromo-1,5-cyclooctadiene (DBCOD) precursor molecule and cause it to undergo a CC covalent coupling reaction to form a polymer chain structure. It is understandable that the specific temperature and duration of the Ullmann coupling reaction can be determined by experiment or adjustment according to the specific situation. In some specific implementation cases of the present invention, the temperature of the Ullmann coupling reaction is 300K~320K, and the duration is 10min~15min.

[0048] In a dehydrogenation cyclization reaction, an oxidant usually captures a hydrogen atom in a molecule, thereby forming a free radical in the molecule; then, the free radical forms a new bond with an adjacent carbon atom, while releasing a hydrogen atom, thereby cyclizing the molecule. In most cases, the dehydrogenation cyclization reaction is a free radical mechanism reaction. In the present invention, the two diagonal carbon atoms in the polycyclooctadiene sp 3 Under the catalytic action of the silver single crystal (111) surface, the hybridized carbon atoms each remove a hydrogen atom to form a free radical, and then a new carbon-carbon bond is formed between the two. At the same time, the removed hydrogen atoms migrate on the silver single crystal (111) surface and combine with each other to form hydrogen molecules, which are then desorbed from the surface. Subsequently, due to the adsorption of the silver single crystal (111) surface, all sp 3 The hybridized carbon atoms are further dehydrogenated to form planar sp 2Hybridized carbon atoms, thereby forming a polypentane chain. It is understood that the temperature and duration of the dehydrogenation cyclization reaction can be determined by experiment or adjustment according to the specific situation. In some specific implementation cases of the present invention, the temperature of the dehydrogenation cyclization reaction is 600K~650K, and the duration is 10min~15min.

[0049] Cross-Dehydrogenative Coupling (CDC reaction) is a cross-coupling reaction that forms CC bonds through the CH bonds of two different reaction substrates under oxidative conditions. In the present invention, under the catalytic action of the silver single crystal (111) surface, the CH bonds in the pentylene unit in the polypentylene chain are broken to form free radicals, and bond with the edge carbon atoms in another polypentylene chain, and then a hydrogen atom is removed for aromatization; the removed hydrogen atoms migrate on the surface and bond with each other to form hydrogen molecules and desorb from the surface. It can be understood that the temperature and duration of the dehydrogenation coupling reaction can be determined by experiment or adjustment according to the specific situation. In some specific implementation cases of the present invention, the temperature of the dehydrogenation coupling reaction is 700K~750K, and the duration is 10min~15min.

[0050] in, Figure 1 FIG. 2 shows a schematic diagram of the preparation process of carbon nanoribbons in a preferred embodiment of the present invention.

[0051] The third aspect of the present invention provides the use of the carbon nanoribbons as described in the first aspect of the present invention in the preparation of carbon-based devices. The carbon-based devices described here are carbon-based chips, carbon-based sensors, etc., but are not limited thereto. Preferably, the carbon-based devices are carbon-based chips.

[0052] The fourth aspect of the present invention provides a carbon-based chip containing conductive wires, which are prepared using the carbon nanostrips described in the first aspect of the present invention. Since the carbon nanostrips in the present invention only contain five-membered carbon rings and seven-membered carbon rings, and do not contain six-membered carbon rings at all, they have excellent conductivity and strong metallic properties, and their resistance is small, which can greatly reduce the heating effect during the operation of the carbon-based chip, and has broad application prospects.

[0053] The present invention is described below by means of specific examples. It should be noted that the following specific examples are only for illustrative purposes and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods without specific conditions or steps are conventional methods, and the reagents and materials used can be obtained from commercial channels.

[0054] Example 1

[0055] This embodiment provides a carbon nanoribbon having pure five-membered carbon rings and seven-membered carbon rings, and the specific preparation method thereof is as follows:

[0056] (1) Using 1,5-dibromo-1,5-cyclooctadiene (DBCOD) as the precursor molecule, in an ultra-high vacuum environment (vacuum chamber pressure less than 5×10 -10 mbar), a film was deposited on the surface of a silver single crystal (111) maintained at 300K using molecular beam epitaxial growth technology (deposition rate was 0.5nm / h, deposition time was 10min), and maintained for 15min, resulting in an Ullmann coupling reaction to form polycyclooctadiene (PCOD).

[0057] (2) The polycyclooctadiene in step (1) is further heated to 650K and maintained for 10 minutes to cause a dehydrogenation cyclization reaction to generate a polypentylene chain (PPTL).

[0058] (3) The polypentadiene chain in step (2) is heated to 700 K and maintained for 15 min to undergo a dehydrogenative coupling reaction to form (5-7) carbon nanoribbons CPHN 1 and CPHN 2, thereby obtaining carbon nanoribbons with pure five-membered carbon rings and seven-membered carbon rings.

[0059] Example 2

[0060] This embodiment provides another carbon nanoribbon having pure five-membered carbon rings and seven-membered carbon rings, and the specific preparation method thereof is as follows:

[0061] (1) Using 1,5-dibromo-1,5-cyclooctadiene as the precursor molecule, in an ultra-high vacuum environment (vacuum chamber pressure less than 5×10 -10 mbar), a film was deposited on the surface of a silver single crystal (111) maintained at 310K using molecular beam epitaxial growth technology (deposition rate was 1.0nm / h, deposition time was 8min), and maintained for 12min, resulting in an Ullmann coupling reaction to form polycyclooctadiene.

[0062] (2) The polycyclooctadiene in step (1) is further heated to 625 K and maintained for 12 min to cause a dehydrogenation cyclization reaction to generate polypentadiene chains.

[0063] (3) The polypentadiene chain in step (2) is heated to 725 K and maintained for 12 min to undergo a dehydrogenative coupling reaction to form (5-7) carbon nanoribbons CPHN 1 and CPHN 2, thereby obtaining carbon nanoribbons with pure five-membered carbon rings and seven-membered carbon rings.

[0064] The CPHN 1 and CPHN 2 of the carbon nanoribbons prepared in Example 2 were scanned using a scanning tunneling microscope (STM) and an atomic force microscope (AFM). Figure 2 .

[0065] The results show that the carbon nanoribbons prepared in Example 2 have pure five- and seven-membered carbon ring structures, and CPHN 1 and CPHN 2 are planar structures with a thickness of a single carbon atom layer and a width of 1 to 1.2 nm.

[0066] Further, through Figure 3 It can be seen that the carbon nanoribbon CPHN 1 transport IV The curve has a large slope near zero bias, confirming that it has a metallic band structure and good conductivity. I - V The curve has no electronic state density and zero conductivity near zero bias, proving that it is a semiconductor. The energy gap obtained by measurement is about 0.2 eV.

[0067] Example 3

[0068] This embodiment provides another carbon nanoribbon having pure five-membered carbon rings and seven-membered carbon rings, and the specific preparation method thereof is as follows:

[0069] (1) Using 1,5-dibromo-1,5-cyclooctadiene as the precursor molecule, in an ultra-high vacuum environment (vacuum chamber pressure less than 5×10 -10 mbar), a film was deposited on the surface of a silver single crystal (111) maintained at 320K using molecular beam epitaxial growth technology (deposition rate was 1.5nm / h, deposition time was 5min), and maintained for 10min, resulting in an Ullmann coupling reaction to form polycyclooctadiene.

[0070] (2) The polycyclooctadiene in step (1) is further heated to 600 K and maintained for 15 min to cause a dehydrogenation cyclization reaction to form a polypentadiene chain.

[0071] (3) The polypentadiene chain in step (2) is heated to 750 K and maintained for 10 min to cause a dehydrogenative coupling reaction to form (5-7) carbon nanoribbons CPHN 1 and CPHN 2, thereby obtaining carbon nanoribbons with pure five-membered carbon rings and seven-membered carbon rings.

[0072] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A carbon nanoribbon, characterized in that: The method comprises a first carbon nanoribbon and a second carbon nanoribbon, wherein: The first carbon nanoribbon has P2 / m The point group contains only five-membered carbon rings and seven-membered carbon rings, which are metallic; The second carbon nanoribbon has Pmc2 It has a point group of 1 and contains only five-membered carbon rings and seven-membered carbon rings, and is a semiconductor.

2. The carbon nanoribbon according to claim 1, characterized in that: The first carbon nanoribbon and the second carbon nanoribbon are both made of carbon and hydrogen. sp 2 Hybridized.

3. The carbon nanoribbon according to claim 1, characterized in that: The first carbon nanoribbon and the second carbon nanoribbon are both planar structures; And / or, the thickness of the first carbon nanoribbon and the second carbon nanoribbon are both a single carbon atom layer, and the width is 1 nm to 1.2 nm.

4. A method for preparing the carbon nanoribbon according to any one of claims 1 to 3, characterized in that: The following steps are involved: Provide 1,5-dibromo-1,5-cyclooctadiene as a precursor molecule, under vacuum pressure less than 5×10 -10 Under the ultra-high vacuum environment of mbar, a coating film is deposited on the substrate surface to form polycyclooctadiene through the Ullmann coupling reaction; The polycyclooctadiene is subjected to a dehydrogenation cyclization reaction to generate a polypentene chain; The polypentene chain is subjected to a dehydrogenation coupling reaction to form a carbon nanoribbon containing only five-membered carbon rings and seven-membered carbon rings.

5. The method according to claim 4, characterized in that The substrate is a silver single crystal (111) and is maintained at a temperature of 300K to 320K, and the deposition method is molecular beam epitaxial growth; And / or, the deposition temperature is 300K~320K, the speed is 0.5nm / h~1.5nm / h, and the duration is 5min~10min.

6. The method according to claim 4, characterized in that The temperature of the Ullmann coupling reaction is 300K~320K, and the duration is 10min~15min.

7. The method according to claim 4, characterized in that The temperature of the dehydrogenation cyclization reaction is 600K~650K, and the duration is 10min~15min.

8. The method according to claim 4, characterized in that The temperature of the dehydrogenation coupling reaction is 700K~750K, and the duration is 10min~15min.

9. Use of the carbon nanoribbon according to any one of claims 1 to 3 in the preparation of carbon-based devices.

10. A carbon-based chip containing conductive wires, characterized in that: The conductive wire is prepared by using the carbon nanoribbon according to any one of claims 1 to 3.

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