WO2017050263A1

WO2017050263A1 - Novel nanocarbon crystal

Info

Publication number: WO2017050263A1
Application number: PCT/CN2016/099790
Authority: WO
Inventors: 郭留希; 赵清国; 张洪涛; 杨晋中; 刘永奇; 武艳强
Original assignee: 郑州华晶金刚石股份有限公司
Priority date: 2015-09-25
Filing date: 2016-09-23
Publication date: 2017-03-30
Also published as: CN105384160B; CN105384160A

Abstract

The invention relates to the field of carbon material preparation. Disclosed is a novel nanocarbon crystal having an average particle diameter R and containing 99-100% of carbon. R satisfies the following condition: 0 < R ≤ 10 nm. The carbon crystal has a quasi-spherical shape. A surface carbon atom of the carbon crystal and a carbon atom in a diamond phase on an inner layer of the carbon crystal constitute a carbon atom dimer structure. The two carbon atoms of the carbon atom dimer structure are in an asymmetric arrangement. The novel nanocarbon crystal product has high crystallinity, surface activity and adsorbability, is of a regular and controllable shape, and has a loss rate controlled to be within 1%, can absorb full-spectrum solar energy, and a surface carbon atom thereof has high activity.

Description

Specification Name of Invention: A Novel Nano Carbon Crystal

Technical field

[0001] The invention belongs to the technical field of carbon materials, and particularly relates to a novel nano carbon crystal.

Background technique

[0002] Carbon is one of the most widely used elements in the world, and carbon is currently the most widely used material in the world. With the changes of the Sui Dynasty and the advancement of science, people continue to use carbon and discover carbon, and invented many carbon materials, such as: fullerenes, carbon nanotubes, graphene, etc., nanocarbon crystals are in the carbon material family. A new member. The emergence of new materials means an improvement in the material preparation process. The industrial preparation method of fullerenes is mainly a combustion method, and benzene and toluene are mainly used to obtain C ₆ by incomplete combustion under the action of oxygen. With C ₇ . The mixture, the same amount of toxic gas is discharged to pollute the environment, and subsequent purification by other organic substances is required, and the preparation process is complicated. The industrial preparation method of carbon nanotubes is an arc method. The graphite electrode is placed in a reaction vessel filled with nitrogen or argon gas, and an arc is generated between the two poles. Under this condition, c _6Q , amorphous c, and more are prepared. The carbon nanotubes of the layer can not be purified by C _{6Q to} obtain high purity carbon nanotubes, and the preparation method has high energy consumption. The preparation method of graphene is mainly a redox method, the graphite is oxidized by an oxidizing agent, the layer spacing of graphite is increased, and then separated by a physical method, and finally the graphene is obtained by chemical reduction, and the graphene yield by the method is obtained. High, but the quality of the product is low.

technical problem

[0003] It is an object of the present invention to provide a novel nanocarbon crystal.

Problem solution

Technical solution

[0004] Based on the above object, the present invention adopts the following technical solutions: A novel nano carbon crystal having a spherical morphology, and C atoms on the surface of the carbon crystal and C atoms in the inner diamond phase constitute dimerization of C atoms. In the bulk structure, two carbon atoms in the dimeric structure of the C atom are asymmetrically distributed.

Preferably, the lattice spacing is 0.21 nm.

Preferably, the average particle diameter is R, 0 < R ≤ 10 nm. [0007] Preferably, the carbon crystal has a C content of 99 to 100%.

[0008] The nanocarbon crystal is prepared by the following method, and the steps are:

[0009] (1) Preliminary crushing: After the diamond raw material is mechanically crushed, the fine material of 500 mesh or more is sieved, and the fine material is repeatedly sieved more than once to ensure the accuracy of the sorting granularity;

[0010] (2) Re-crushing: The fine material of 500 mesh or more is sent to the airflow crusher, and the fine material is crushed by the high-pressure airflow, and the fine powder of 10000 mesh or more is sieved, and the sieve residue is returned to the airflow crusher. Re-breaking

[0011] (3) Pickling: The fine powder of 10000 mesh or more is washed with concentrated sulfuric acid and concentrated nitric acid, dilute hydrochloric acid and hydrofluoric acid, and then washed with deionized water until the pH of the washing liquid is close. 7; the concentrated sulfuric acid and concentrated nitric acid mixture is composed of a mass fraction of 98% concentrated sulfuric acid and a mass fraction of 10% concentrated nitric acid according to a mass ratio of 5:1;

[0012] (4) Sorting: The washed material is centrifuged, and the upper layer liquid is taken for 4-7 days of precipitation sorting, the supernatant liquid is removed, and the lower layer precipitate is dried to obtain the finished nano carbon crystal; centrifugal separation In the step, the centrifugal chamber is 30 min - 2 h, and the rotation speed is 8000 rpm - 20,000 rpm.

[0013] Further, in the step (1), the diamond is sieved out of the mesh of the mechanical pulverizer by 32 mesh or more, and the granules are sieved by the multi-stage vibrating sieve to separate fine materials of 500 mesh or more.

Advantageous effects of the invention

Beneficial effect

[0014] Compared with the prior art, the nanocarbon crystal provided by the invention has the following advantages:

[0015] (1) The C content of the nanocarbon crystal is between 99% and 100%, the purity is high, the particle size range is narrow, 0<R≤10 nm, the product has strong crystallinity, strong surface activity and strong adsorption capacity. The shape is regular and controllable, the loss rate is low, and the loss rate can be controlled within 1%.

[0016] (2) The nanocarbon crystal can absorb the full spectrum of solar energy and has high surface carbon atom activity. When combined with a catalyst such as Ti0 ₂ , it can absorb visible light under illumination and emit short-wavelength light of 325-425 nm, thereby exciting TiO. _{The second} catalyst forms an electron-hole pair, and the electron-hole pair is converted into an active group, thereby degrading the organic dye molecule. Since the nano-carbon crystal is on the surface of the catalyst such as TiO ₂ , it can function to transfer electrons and promote the charge. The separation, electron transport along the surface of the nanocarbon crystal, can prolong the cavity life of the catalyst such as TiO ₂ and improve the catalytic activity. [0017] (3) The surface of the nanocarbon crystal has a dimeric structure of asymmetrically distributed C atoms, has high surface activity, is easily functionalized by the surface, and can be used for various cosmetics, and has the same wear resistance. It is also used for various cleaning agents, oil additives, coating additives, etc. to increase wear resistance.

[0018] (4) According to the Raman test result, the nanocarbon crystal of the invention has no photoluminescence phenomenon, and can be used in the field of stealth aircraft surface coating (requires good optical concealing performance and high temperature and friction resistance), or To make special optical devices, such as optical resonators, limit displays, etc., have unique applications in the field of optics.

[0019] (5) The nanometer carbon crystal has a small particle size, is easily dispersed in the plating solution, and is also easily adsorbed on the surface of the object to be plated, forming a diamond film on the surface of the plated member, and the film has good thermal conductivity. Abrasion resistant, it can be used for surface treatment of various heat and wear parts.

[0020] (6) The nanocarbon crystal phase is composed of a diamond phase, and has high hardness, high wear resistance, high thermal conductivity, high stability, oleophilic hydrophobicity, etc., and can be widely used to improve conventional grinding operations and improve Grinding efficiency and reducing costs.

Brief description of the drawing

DRAWINGS

1 is a block diagram of a process flow of the present invention;

2 is a TEM analysis diagram of nanocarbon crystals prepared in Example 1;

3 is an XRD spectrum of the nanocarbon crystal prepared in Example 1;

4 is an EDS spectrum of the nanocarbon crystal prepared in Example 1;

5 is a Raman spectrum of nanocarbon crystals prepared in Example 1;

6 is a MAS NMR spectrum of the nanocarbon crystal prepared in Example 1.

Embodiments of the invention

[0027] The present invention will be described in detail below with reference to the embodiments.

Embodiment 1

[0029] A novel nano-carbon crystal having an average particle diameter of R, 0 < R ≤ 10 nm, a C content of 99 to 100 < 3⁄4, the carbon crystal is a spheroidal morphology, a C atom on the surface of the carbon crystal and an inner diamond layer The C atom of the phase constitutes a dimer structure of the C atom, and the two carbon atoms in the dimer structure of the C atom are asymmetrically distributed with a lattice spacing of 0.21 nm. Embodiment 2

[0031] The nano carbon crystal is prepared by the following method, and the process flow diagram is as shown in FIG. 1 , and the steps are as follows:

[0032] (1) Preliminary crushing: First, the diamond raw material is sent into the crushing cavity of the mechanical crusher, and is broken by the action of the hammer head inside the crusher, and the crushed material passes through different mesh screens, larger than the sieve. The material of the mesh diameter is left to be re-crushed inside the crusher, and the fine particles filtered by the finest sieve under the crusher are collected through the sieve plate (the mesh number is not less than 32 mesh), and the mesh is filtered by other meshes. The material can be sold as coarse material or used to prepare other granular materials; the particles above 32 mesh are multi-layered by a multi-layer vibrating machine for initial particle size, the vibrating screen is generally controlled at 30 min~3 h, and the mesh number is from 40 mesh. Arranged to 500 mesh, the coarse material sorted by the 40 mesh screen is returned to the mechanical crusher for re-crushing (Fig. 1A), and the material collected from the 40 mesh to 500 mesh sieve is used to prepare other granular materials, passing through a 500 mesh sieve. The fine material collected after the net is used to prepare nano carbon crystals. To ensure the accuracy of the sorting granularity, the collected fine materials are repeatedly sieved and selected more than once.

[0033] (2) Re-crushing: The fine material sieved in step (1) is sent into the crushing chamber of the airflow crusher, and the fine material is crushed by the high-pressure airflow, and the sieve mesh is collected at the receiving port of the airflow crusher. After the separation, the mesh number of the mesh is arranged from 1000 mesh to 10000 mesh from high to low, and the fine powder selected by the 10000 mesh screen is collected for preparing the nano carbon crystal, and the other mesh mesh is used for preparation. The other material is still returned to the airflow crusher for re-crushing, and the coarse material collected by the 1000 mesh screen is automatically returned to the airflow crusher for re-crushing (Fig. 1B).

[0034] (3) pickling: the collected 10,000 mesh fine powder is placed in concentrated sulfuric acid and concentrated nitric acid mixture for pickling for 1 ~ 5h, filtered, washed, the concentrated sulfuric acid and concentrated nitric acid mixture by mass The fraction of 98% concentrated sulfuric acid and the mass fraction of 10% concentrated nitric acid are mixed according to the mass ratio of 7:1.2; then the fine powder is placed at a temperature of 120 ° C ~ 180 ° C with a mass fraction of 5 < 3⁄4 ~ 10 < 3⁄4 4~l lh in hydrochloric acid, filtered; then put the fine powder in hydrofluoric acid for 5~20 h, remove the metal impurities in the material and the impurities attached to the material during mechanical crushing and airflow breaking, and then use Ion water is washed until the pH of the cleaning solution is close to 7.

[0035] (4) Sorting: The washed material is centrifuged, the centrifugation is 1 h, the rotation speed is 1000 rpm, and the core mixture is separated by centrifugation and the bottom sediment of the centrifuge tube is taken; The mixed solution is subjected to 5 days of precipitation sorting. The longer the sedimentation time is, the finer the particle size of the sorted material is. The supernatant is removed after the sedimentation, and the lower layer precipitate is dried after the particle size test. Nano carbon crystal. The sediment at the bottom of the centrifuge tube can be returned to the airflow crusher to continue to be broken or sold as a coarser-grained finished material. The prepared nano carbon crystal has a particle size of 9-10 nm, and the particle size is a small range. The peak of the particle size, the particle size of the peak is at least 98% or more in the particle size sorted by the corresponding sorting.

Embodiment 3

[0037] The preparation process of Example 3 is different from that of Embodiment 2 in that: the centrifugal chamber is 30 minutes, and the rotation speed is 200.

At OOrpm, the sedimentation was divided into 4 days.

[0038] The prepared nanocarbon crystal has a particle size of 6 to 8 nm.

Example 4

[0040] The preparation process of Example 4 is different from that of Example 2 in that: the centrifugal day is lh, the rotation speed is lOOOOr pm, and the precipitation separation time is 6 days.

[0041] The prepared nano carbon crystal has a particle size of 5 to 6 nm.

Embodiment 5

[0043] The preparation process of Example 5 is different from that of Example 2 in that: the centrifugal chamber is 2 h, the rotation speed is 20000 rpm, and the sedimentation time is 7 days.

[0044] The prepared nano carbon crystal has a particle size of 0 to 5 nm.

[0045] performance test

(1) TEM analysis

2 is a TEM analysis diagram of the nanocarbon crystal provided in Example 1, in which: a: nanocarbon crystal; b: explosion method nanodiamond; 1 represents a partial enlarged view, 2 represents a HRTEM image, and 1 is in the upper left The illustration of the corner is the corresponding SAED diagram.

[0048] It can be seen from the TEM analysis chart of FIG. 2 that the nanocarbon crystal prepared in the embodiment is approximately spherical, the morphology is relatively regular, the particle size is 2-5 nm, and the explosive nanodiamond is composed of some agglomerated particles. , and the morphology is not regular, the particle size is between 5-10nm. It can be seen from the corresponding SAED diagram that both materials have polycrystalline structure, and the corresponding HRTEM image can measure the crystal of nano-carbon crystal. The lattice spacing is 0.21 nm, which is very close to the lattice spacing d=0.206 nm of the (111) crystal plane of the diamond phase, which indicates that the nanocarbon crystal prepared by the invention has a diamond phase structure.

(2) XRD analysis

3 is an XRD spectrum of the nanocarbon crystal prepared in Example 1, in which: a: an explosion method nanodiamond; b: a nanocarbon crystal. [0051] As can be seen from FIG. 3, the peak positions of the two materials are all at about 44°, and compared with the standard PDF card, the diamond-like Miller index corresponds to the (111) crystal plane, which proves again. Both of these materials are composed of diamond phase, but it can be seen that nano-carbon crystals have a large amorphous package between 20° and 40°, and the crystallinity of nano-carbon crystals is better than that of explosive nano-diamonds. Weak, but still have strong crystallinity. According to Xie Le formula

[number]

, K is a constant, β is a full width at half maximum, λ is the wavelength of Κα ray of Cu, and the calculated result is D _BZ = 8.5 nm, D _c = 3.5 nm. The grain size of the nanodiamond synthesized by the explosion method is about 2.4 of the nanometer carbon crystal. Therefore, it can be seen that the nano-carbon crystal grains prepared by the invention are smaller than the nano-diamonds synthesized by the explosion method, and have many grain boundaries. Different degrees of distortion occur inside the small crystal grains, thereby affecting the properties of the material. Therefore, the nano carbon crystal synthesized by the present invention is superior in activity to the nano diamond synthesized by the explosion method.

(3) EDS analysis

4 is an EDS spectrum of the nanocarbon crystal prepared in Example 1, in which: a: nanocarbon crystal; b: explosive method nanodiamond.

[0054] As can be seen from FIG. 4, the nanocarbon crystals prepared by the present invention are basically composed of C elements, and the purity is high.

This is similar to the nano-diamond prepared by the explosion method and belongs to the C material.

(4) Raman analysis

5 is a Raman spectrum of the explosive nano-diamonds and nano-carbon crystals, in which: a: an explosion-type nano-diamond, b: a nano-carbon crystal prepared in Example 1.

[0057] It can be clearly seen from FIG. 5 that the two carbon materials obviously have different Raman spectra, and the nano-diamond synthesized by the explosion method also has the characteristic Raman peak D peak and G peak typical of the C material, and the present invention The synthesized nanocarbon crystals do not have any Raman peak, which indicates that the nanocarbon crystals prepared by the present invention have different carbon atom arrangements from the explosive nanodiamonds. Infrared spectroscopy only has a strong absorption signal for molecules with infrared activity. For pure C element crystals, the structure cannot be detected by infrared spectroscopy. The so-called infrared activity refers to a structure in which the dipole change is not zero and the structure is more symmetrical, so the dipole change is smaller, for example. CC, C=C, C≡C, 0-0, N≡N, etc. These homonuclear diatomic pairs are infrared inactive, so it is difficult to observe these homonuclear diatomic pairs in the infrared spectrum. Telescopic vibration characteristic peaks (if such homonuclear diatomic atoms are to be observed, a relatively weak infrared absorption peak can be detected by attaching an asymmetric group around them). However, in general, the Raman activity of the homonuclear diatomic pair with weak infrared activity is relatively strong, so it can be concluded that the nanocarbon crystal is different from the C atom arrangement of the explosive nanodiamond.

(5) MAS NMR analysis

6 is a MAS NMR spectrum of the nanocarbon crystal and the explosive nanodiamond prepared in Example 1, wherein: a: the nanocarbon crystal prepared in Example 2; b: the explosion method nanodiamond.

[0060] It can be seen from FIG. 6 that both the carbon nanocrystals and the explosive nanodiamonds have two C peaks, which indicates that there are two different carbon atoms C^nC _{2 in the} nanocarbon crystal and the explosive nanodiamond sample. At 34ppm and 30ppm respectively. In general, the 0 _{C of the} sp ³ orbital hybrid carbon is usually 0 to 60 ppm, the δ c of the sp ² orbital hybrid carbon is usually 100 to 220 ppm, and the δ _{c of the} sp orbital hybrid carbon is usually 60 to 90 ppm. We can see that the δ _c of C ₁ and C ₂ of both samples a and b are between ₀ and 60 ppm, and there is no peak at other positions, although the peak positions of these two peaks are between 0 and 60 ppm. Between, but C ^nC ₂

The peak positions are 4ppm apart, and the positions are very close, which indicates that the chemical environment of C ^nC ₂ is relatively close. Combined with EDS analysis, the nano-carbon crystals and the explosive nano-diamond samples are composed of C elements, so C, and C ₂ has a different structure. According to Raman spectroscopy results, it is known that the nanocarbon crystal synthesized by the invention does not have any Raman spectral peak, and the nanodiamond synthesized by the explosion method has the characteristic Raman peak of the C material. Based on the above analysis, we can infer the nano carbon crystal synthesized by the invention and the explosion method. The surface of the nanodiamond is different in C atom arrangement. The C atom on the surface of the carbon crystal synthesized by the present invention and the C atom of the inner diamond phase constitute a dimer structure of C atoms, and the two carbon atoms are asymmetrically distributed. The C atom of the nanodiamond surface synthesized by the explosion method and the C atom of the diamond phase also constitute a dimer structure of C atoms, and the two C atoms are symmetrically distributed, so that two distinct ones appear. Raman Peak. Asymmetric C atom arrangement is more active than symmetrically arranged C atoms, and it is easier to recombine with different groups. The C atom on the surface of the same particle is more active and easy to agglomerate. For diamonds, surface functionalization is easier to perform.

The nanocarbon crystal provided by the invention can absorb the full spectrum of solar energy and has high surface carbon atom activity. When combined with a catalyst such as Ti0 ₂ , it can absorb visible light under illumination and emit short-wavelength light of 325-425 nm. Thus, the catalyst such as TiO _{2 is} excited to form an electron-hole pair, and the electron-hole pair is converted into an active group, thereby degrading the organic dye molecule. Since the nano-carbon crystal is on the surface of the catalyst such as TiO ₂ , it can transmit electrons. The action, which promotes the separation of charges, and the transport of electrons along the surface of the nanocarbon crystal, can prolong the hole lifetime of the catalyst such as Ti0 ₂ and improve the catalytic activity. The carbon atom arrangement on the surface of the nanocarbon crystal synthesized in the present application is asymmetric, and the carbon atoms of the surface layer and the carbon atoms of the inner layer constitute an asymmetric dimer structure, which is relative to the explosion method nanodiamond. , more active, more easily surface-functionalized, easier to recombine with other materials in the form of covalent or non-covalent bonds. This carbon crystal can be used in extreme displays due to its special photoluminescence properties. Optical resonators, etc., due to their small particle size and large specific surface area, can be used to prepare various adsorption membranes, such as seawater desalination membrane, brackish water desalination membrane, deionized water to prepare membranes, etc., and also have strong catalytic action. , can be used to prepare non-metal catalyzed Qi 1J. The carbon crystal synthesized by the invention is a material with very good biocompatibility, has no toxic and side effects, can be compounded with the active component of the drug, and can be used for directed drug conduction, so that the effective molecule of the drug can rapidly pass through the phospholipid bilayer of the human body. Quickly reach the lesion site, achieve targeted treatment of drugs, improve drug utilization, and reduce treatment cycle. Carbon crystal can also be used in a variety of daily cosmetics, such as: facial cleanser, soap, soap, toothpaste, etc., to achieve the purpose of less whitening effect, can effectively remove melanin from human skin and make teeth whiter . The nanocarbon crystal synthesized by the invention has strong surface activity, strong composite property with other materials, and has wear resistance, so it can be used for compounding with various lubricating oils, improving lubricity of lubricating oil and preparing various coatings. Agent. Since the carbon crystal synthesized by the invention has a small particle size, it is easy to disperse in the plating solution, and is also easily adsorbed onto the surface of the object to be plated, and a diamond film is formed on the surface of the plated part, and the film has good thermal conductivity and wear resistance. It can be used for surface treatment of all kinds of heat-generating and wearable parts (including non-stick pan).

Claims

Claim

[Claim 1] A novel nanocarbon crystal, characterized in that the carbon crystal is a spheroidal shape, and the surface of the carbon crystal

The C atom and the C atom of the inner diamond phase constitute a dimer structure of the C atom, and the two carbon atoms in the dimer structure of the C atom are asymmetrically distributed.

[Claim 2] The novel nanocarbon crystal according to claim 1, wherein the lattice spacing is 0.21 η m.

[Claim 3] The novel nanocarbon crystal according to claim 1 or 2, wherein the average particle diameter is R

, 0 < R ≤ 10 nm.

[Claim 4] The novel nanocarbon crystal according to claim 3, wherein the carbon crystal has a C content of 99 to 100 < 3⁄4.