CN104386681A - Method for controllable preparation of graphene employing mechanical friction of flake graphite - Google Patents

Abstract

The invention discloses a method for controllable preparation of graphene employing mechanical friction of flake graphite. The method specifically comprises the following steps: ultrasonically dispersing flake graphite in hydrocarbon solvents of C4-C22; controlling the state before mechanical friction of an end surface; adding graphite dispersed oil to a friction gear oil box; controlling the corresponding friction work condition to carry out mechanical friction operation; and then carrying out reduced pressure distillation to recycle a solvent, namely graphite. The preparation method of the graphite disclosed by the invention is simple and controllable; the graphite is easily prepared greatly; the preparation process is environmentally friendly; the product is stable and controllable in quality; and the yield of single-layer graphite is high.

Description

A method for the controllable preparation of graphene by mechanical friction of flake graphite

technical field

The invention relates to a method for preparing graphene, in particular to a method for preparing graphene under the controllable mechanical friction of flake graphite.

Background technique

Graphene is a planar structure material composed of sp ² hybridized carbon atoms. In the past, it was considered that it could not exist independently. Until 2004, Geim et al. successfully separated graphene from graphite by micromechanical exfoliation, confirming that Graphene can exist alone. Graphene has many excellent properties, including ultra-high thermal conductivity, huge specific surface area, extremely high strength and elastic modulus, and ultra-low resistivity, etc. It is used in nano-devices, wear-resistant materials, sensors and new generation Electronic components and other aspects have great application prospects, however, the controllable preparation of graphene has not been well resolved.

At present, the preparation methods of graphene mainly include micromechanical exfoliation method, chemical vapor deposition method, redox method and so on. The micromechanical exfoliation method needs to heat the graphite, then stick the graphite to the glass plate with an adhesive, then place the glass plate in acetone for vibration, and finally use a single crystal silicon wafer to fish out the peeled graphene sheet. The advantage of this method is that the cost is low and single-layer graphene can be prepared, but the disadvantages are also obvious, such as low efficiency and difficulty in mass production. The chemical vapor deposition method is to decompose methane and other hydrocarbon molecules at high temperature and then adsorb and deposit them on the surface of metal catalyst substrate materials. Carbon atoms recombine on the surface of the substrate to form graphene. The advantage of this method is that large-scale graphene can be prepared. The disadvantages are The base material needs to be etched to remove during use, and the formed graphene structure is easily damaged during the removal operation. The oxidation-reduction method is currently the most commonly used method for preparing graphene. This method is to oxidize graphite with strong acid and strong oxidant, and insert oxygen-containing functional groups between the layers to increase the distance between graphite layers, and then perform ultrasonic treatment to oxidize graphite. After the oxide is peeled off, graphene oxide is obtained, and then the oxygen-containing groups are removed by reducing agent to obtain graphene. The advantage of this method is that the operation process is simple and easy to control, but because the product contains more few-layer graphene, and The content of single-layer graphene is relatively small. In addition, most of these reducing agents used are toxic or environmentally harmful components, which limits its large-scale preparation.

It can be seen that the existing graphene preparation methods have both certain advantages and some obvious deficiencies, and it is urgent to develop new methods for graphene preparation.

Contents of the invention

The present invention aims at the deficiencies of the prior art, and provides a method for preparing graphene under the controllable mechanical friction of flake graphite. The technical problems to be solved are: simple and controllable operation, easy macro-preparation, environmentally friendly preparation process, stable and controllable product quality, and high yield of single-layer graphene.

The present invention is realized through the following technical solutions:

Add flake graphite into C4-C22 hydrocarbon solvent, ultrasonically disperse for 30-60min to form graphite dispersed oil; control the state before mechanical friction of the end face, then add graphite dispersed oil to the oil box of the friction device, and start loading to the friction pair The load is 150N-300N, the speed is 0.1-0.8m/s, and the oil temperature is 40-60°C and the friction is 1-2h; finally, the oil sample after friction is taken out, and the friction is reduced under the condition of 0.01-0.03MPa, 70-90°C The solvent is recovered by pressure distillation to obtain graphene.

The flake graphite as described above is characterized in that the particle size is 160-300 μm, the carbon content is more than 99.90%, and the added amount accounts for 0.1-5% of the mass of the solvent;

As mentioned above, the state before the mechanical friction of the control end face is characterized in that the friction pair is in the form of ring-block surface contact, and the friction contact area is 400-800mm ² ; 6 grooves are evenly distributed on the friction surface of the ring-shaped friction pair, and the grooves The opening width is 5mm, and the depth is 10mm; the diameter of the block friction pair is 10-20mm larger than the outer diameter of the ring friction pair; the materials of the ring and block friction pairs are ductile iron, gray cast iron, No. 45 steel, and GCr15 steel. Any two, the friction surface roughness Ra is 0.10-0.60μm.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The preparation operation is simple and controllable, and it is easy to prepare in large quantities. As long as the appropriate flake graphite raw materials and friction pair materials are selected and the corresponding preparation process conditions are adjusted, the required products can be easily controlled and obtained; the amount of raw materials can be enlarged according to the proportion, and the corresponding enlarged amount can be obtained. Graphene products.

2. The preparation process is environmentally friendly, the product quality is stable and controllable, and the yield of single-layer graphene is high. There is no need to use toxic or environmentally harmful ingredients in the preparation process, and the hydrocarbon solvents can be effectively recovered by vacuum distillation; the surface of the prepared graphene can form frictional electrostatic repulsion to ensure that the prepared graphene will not be re-agglomerated , so as to meet the requirements of stable and controllable product quality; through the combined control of friction pair surface roughness, friction load, friction speed, oil temperature, friction time and other factors, the flake graphite raw material can be converted into single-layer graphene, so the single The yield of layer graphene is high.

Description of drawings

Figure 1 is a schematic diagram of an end-face mechanical friction device, in which 1 is an annular friction pair, 2 is a block friction pair, 3 is graphite dispersion oil, 4 is an oil box, and 5 is an oil temperature heating control device.

Fig. 2 is a schematic diagram of an annular friction pair, wherein (a) is a three-dimensional schematic diagram, and (b) is a cross-sectional view.

Figure 3 is a micrograph of flake graphite raw materials and graphene products, wherein (a) is flake graphite, (b) is an example of graphene 1, and (c) is an example of graphene 2.

Figure 4 is a Raman spectrogram, wherein (a) is an example of graphene 1, and (b) is an example of graphene 2.

specific embodiment

In order to better understand the present invention, the present invention is illustrated by the following specific examples, but these examples do not limit the present invention.

Example 1: Add 1.0g of flake graphite with a particle size of 160-220μm and a carbon content of 99.95% into 99g of C4-C12 hydrocarbon solvent, ultrasonically disperse for 40min, and form graphite dispersion oil; control the state before mechanical friction of the end surface, and then Graphite dispersed oil was added to the oil box of the mechanical friction device, and the load was started until the load of the friction pair was 150N, the speed was 0.2m/s, and the oil temperature was 45°C for 1.2h; MPa, under the condition of 75°C, the solvent is recovered by distillation under reduced pressure to obtain graphene. Among them, the state before the mechanical friction of the end face is: the friction pair is in the form of ring-block surface contact, and the friction contact area is 423.9mm ² ; The opening width is 5mm and the depth is 10mm; the diameter of the block friction pair is 45mm; the ring and block friction pair materials are ductile iron and No. 45 steel respectively, and the friction surface roughness Ra is 0.22μm and 0.38μm.

Example 2: Add 50g of flake graphite with a particle size of 250-300μm and a carbon content of 99.96% into 950g of C10-C22 hydrocarbon solvent, ultrasonically disperse for 60min, and form graphite dispersed oil; control the state before mechanical friction of the end surface, and then put the graphite Add the dispersed oil into the oil box of the mechanical friction device, start loading until the load of the friction pair is 300N, the speed is 0.6m/s, and the oil temperature is 50°C for 2h; Under the condition of 85°C, the solvent is recovered by distillation under reduced pressure to obtain graphene. Among them, the state before the mechanical friction of the end face is: the friction pair is in the form of ring-block surface contact, and the friction contact area is 728.5mm ² ; The opening width is 5 mm, the depth is 10 mm; the diameter of the block friction pair is 80 mm; the ring and block friction pairs are made of gray cast iron and GCr15 steel cast iron respectively, and the friction surface roughness Ra is 0.32 μm and 0.45 μm, respectively.

Claims (3)

1. A method for the controllable preparation of graphene by mechanical friction of flake graphite, is characterized in that, flake graphite is added in the hydrocarbon solvent of C4-C22, ultrasonic dispersion 30-60min, forms graphite dispersed oil; Control end face mechanical friction front state , and then add the graphite dispersion oil into the oil box of the friction device, start loading until the load of the friction pair is 150N-300N, the speed is 0.1-0.8m/s, and the oil temperature is 40-60℃ for 1-2h; finally put The oil sample after rubbing is taken out, and the solvent is recovered by distillation under reduced pressure at 0.01-0.03MPa and 70-90°C to obtain graphene. 2. the method for preparing graphene under the controllable mechanical friction of flake graphite according to claim 1, is characterized in that: described flake graphite, its particle diameter is 160-300 μ m, and carbon content is more than 99.90%, and addition accounts for solvent quality 0.1-5%. 3. the method for preparing graphene under the controllable mechanical friction of flake graphite according to claim 1 is characterized in that: the state before the mechanical friction of the control end face adopts the ring-block surface contact form of the friction pair, and the friction contact area is 400-800mm ² ; 6 grooves are evenly distributed on the friction surface of the ring friction pair, the opening width of the groove is 5mm, and the depth is 10mm; the diameter of the block friction pair is 10-20mm larger than the outer diameter of the ring friction pair; the ring and block friction pair The materials are any two of ductile iron, gray cast iron, No. 45 steel, and GCr15 steel, and the friction surface roughness Ra is 0.10-0.60 μm.