CN104591176B - A kind of preparation method of Graphene - Google Patents

Abstract

The invention provides a method for preparing graphene, comprising the following steps: A) mixing biomass materials, anionic surfactants and water, performing a hydrothermal reaction to obtain a precursor, and the temperature of the hydrothermal reaction is 150- 250°C, the time of the hydrothermal reaction is 1 to 24 hours; B) mixing the metal catalyst with the precursor obtained in the step A) to obtain a precursor containing the metal catalyst; C) the step B) obtained The precursor containing the metal catalyst is heated to obtain graphene. The preparation method provided by the invention uses biomass material as carbon source, and the reaction of biomass material under hydrothermal conditions can produce gas phase products. Form carbon hollow spheres as templates, and obtain precursors with thinner spherical shells and higher surface activity, which are more easily catalyzed by metal catalysts, and graphene with a higher degree of graphitization can be obtained.

Description

A kind of preparation method of graphene

technical field

The invention belongs to the technical field of carbon materials, in particular to a method for preparing graphene.

Background technique

Graphene is the thinnest two-dimensional material in the world. Its thickness is only 1/200,000th that of a hair, but its strength is the highest among known materials, 100 times higher than the best steel. The force required to cross-section a single layer of graphene is 200 times that of steel. The study found that 100nm graphene can withstand a maximum pressure of about 2.9 micronewtons, which is equivalent to applying a pressure of 55 newtons to break a 1m-long graphene. If a graphene film with a thickness of 100nm is made, it can withstand a pressure of about 20,000 Newtons, so a packaging bag made of graphene can carry items weighing about two tons, which fully demonstrates that graphene is the strongest material in the world .

In recent years, people continue to explore new methods to increase the output of graphene. At present, graphene material powder can be prepared by various methods, such as mechanical exfoliation method, oxidation-reduction method, crystal epitaxial growth method, chemical vapor deposition method , organic synthesis and exfoliation of carbon nanotubes. Among these methods, the preparation efficiency of mechanical exfoliation method and epitaxial growth method is very low, and it is difficult to meet the needs of large-scale. Although the chemical vapor deposition method can obtain large-scale continuous graphene films, it is only suitable for micro-nano electronic devices or transparent conductive films, but it cannot meet the large-scale needs in the field of energy storage materials and functional composite materials. The oxidation-reduction method is relatively stable and widely used, but due to the need to use a large number of strong acids and strong oxidants in the oxidation-reduction process, such as concentrated nitric acid, concentrated sulfuric acid, potassium permanganate or potassium chlorate, etc., it not only brings great harm to the environment Pollution will also bring certain risks to the operation process.

The catalytic activation method is a new method of preparing graphene. The catalytic activation method uses biomass materials as the carbon source, uses the abundant functional groups on the surface of the biomass to physically adsorb or ion-exchange metal ions, mixes with pore-forming agents, and is inert at high temperature. Carbonization under atmosphere to prepare porous graphene. Since the catalytic activation method does not use strong acids and strong oxidants, it has less environmental pollution. However, the graphene prepared by the existing catalytic activation technology can only graphitize the surface of the material, and the overall graphitization degree of the biomass material is not high. , affecting product quality.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of graphene, the degree of graphitization of the graphene obtained by adopting the preparation method provided by the invention is higher, and the product quality obtained is better.

The invention provides a kind of preparation method of graphene, comprises the following steps:

A) mixing biomass material, anionic surfactant and water, and performing a hydrothermal reaction to obtain a precursor, the temperature of the hydrothermal reaction is 150-250°C, and the time of the hydrothermal reaction is 1-24 hours;

B) mixing the metal catalyst with the precursor obtained in step A) to obtain a precursor containing the metal catalyst;

C) heating the metal catalyst-containing precursor obtained in step B) to obtain graphene.

Preferably, the biomass material includes one or more of glucose, sucrose, fructose, sorbose, galactose, and mannose.

Preferably, the anionic surfactant includes one or more of sodium lauryl sulfate, sodium dodecylsulfonate, sodium dodecylbenzenesulfonate and sodium stearate.

Preferably, the mass ratio of the biomass material to the anionic surfactant is (10-50):1.

Preferably, the metal catalyst in step B) includes one or more of iron salts, ferrous salts, nickel salts and cobalt salts.

Preferably, the mass ratio of the metal catalyst to the precursor obtained in step A) is (0.01˜1):1.

Preferably, the heating temperature in step C) is 800-1200°C;

The heating time is 1-5 hours.

Preferably, the precursor obtained in the step A) has a hollow spherical structure, and the thickness of the hollow spherical shell is 2-30 nm.

Preferably, said step A) specifically includes:

Mix biomass materials, anionic surfactants, hydrofluoric acid and water, and perform a hydrothermal reaction to obtain a precursor, the temperature of the hydrothermal reaction is 150-250°C, and the time of the hydrothermal reaction is 1-24 Hour;

The molar concentration of the hydrofluoric acid is 0.01-2 mol/L.

Preferably, the step B) specifically includes: mixing the pore-forming agent with the metal catalyst-containing precursor obtained in the step A), and heating to obtain graphene;

The pore forming agent includes one or more of water vapor, potassium hydroxide, potassium oxide, zinc chloride, phosphoric acid, sodium oxide and sodium hydroxide;

The mass ratio of the pore forming agent to the biomass material in the step A) is (1-5):1.

The invention provides a method for preparing graphene, comprising the following steps: A) mixing biomass materials, anionic surfactants and water, performing a hydrothermal reaction to obtain a precursor, and the temperature of the hydrothermal reaction is 150- 250°C, the time of the hydrothermal reaction is 1 to 24 hours; B) mixing the metal catalyst with the precursor obtained in the step A) to obtain a precursor containing the metal catalyst; C) the step B) obtained The precursor containing the metal catalyst is heated to obtain graphene. The preparation method provided by the present invention uses biomass material as a carbon source, and the reaction of biomass material under hydrothermal conditions can produce gas phase products, such as CO ₂ , CO and H ₂ , etc., and the anionic surfactant can enrich these bubbles With the biomass material in the bulk solution, and form carbon hollow spheres with bubbles as a template, the obtained carbon hollow spheres have a thin shell and are rich in a large amount of anionic surfactants, which dissociate into negatively charged in aqueous solution group, it is easier to adsorb positively charged metal ions such as iron and nickel, and carbon hollow spheres are more likely to be catalyzed by metal catalysts in the subsequent heating process to obtain graphene with a higher degree of graphitization.

Further, the present invention can also carry out fluorination treatment in the hydrothermal process, and carry out fluorination modification on the obtained carbon hollow spheres, so that the carbon hollow spheres have stronger electronegativity, which is more conducive to the adsorption of positively charged metals particle.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is the TEM figure of the precursor obtained in Example 1 of the present invention;

Fig. 2 is the SEM figure of the graphene that the embodiment of the present invention 1 obtains;

Fig. 3 is the TEM figure of the graphene that the embodiment of the present invention 1 obtains;

Fig. 4 is the graphene specific surface area figure that the embodiment of the present invention 1 obtains;

Fig. 5 is the porosity figure of the graphene that the embodiment of the present invention 1 obtains;

Fig. 6 is the Raman spectrum of the graphene that the embodiment of the present invention 1 obtains;

Fig. 7 is the SEM picture of the precursor obtained in Example 2 of the present invention;

Fig. 8 is the TEM picture of the precursor that comparative example 1 of the present invention obtains;

Fig. 9 is the SEM figure of the graphene that comparative example 1 of the present invention obtains;

10 is a TEM image of graphene obtained in Comparative Example 1 of the present invention.

detailed description

The invention provides a kind of preparation method of graphene, comprises the following steps:

A) mixing biomass material, anionic surfactant and water, and performing a hydrothermal reaction to obtain a precursor, the temperature of the hydrothermal reaction is 150-250°C, and the time of the hydrothermal reaction is 1-24 hours;

B) mixing the metal catalyst with the precursor obtained in step A) to obtain a precursor containing the metal catalyst;

C) heating the metal catalyst-containing precursor obtained in step B) to obtain graphene.

The degree of graphitization of the graphene obtained by the preparation method provided by the invention is relatively high, and the quality of the obtained product is relatively good.

In the present invention, the biomass material, anionic surfactant and water are mixed, and a hydrothermal reaction is carried out to obtain a precursor. In the present invention, the biomass material, anionic surfactant and water are mixed, ultrasonicated, and then the ultrasonicated The mixture undergoes a hydrothermal reaction to obtain a precursor. In the present invention, the biomass material preferably includes one or more of glucose, sucrose, fructose, sorbose, galactose and mannose, more preferably one or more of glucose, sucrose and mannose The anionic surfactant preferably includes one or more of sodium lauryl sulfate, sodium dodecylsulfonate, sodium dodecylbenzenesulfonate and sodium stearate, more preferably includes dodecyl sodium Sodium alkylsulfate and/or sodium dodecylbenzenesulfonate; the water used for mixing with the biomass material and anionic surfactant is preferably deionized water. In the present invention, the mass ratio of the biomass material to the anionic surfactant is (10-50):1, more preferably (12-30):1, most preferably 15:1; the biomass The mass ratio of material to water is preferably 1:(8-15), more preferably 1:(9-13), and most preferably 1:(10-12).

In order to make the obtained precursor have stronger electronegativity, the present invention preferably mixes the biomass material, anionic surfactant and hydrofluoric acid solution, and performs ultrasonication to obtain the precursor. In the present invention, the molar concentration of the hydrofluoric acid solution is preferably 0.01 to 2 mol/L, more preferably 0.05 to 1.5 mol/L, and most preferably 0.1 to 0.5 mol/L. The dosage is not particularly limited.

In the present invention, the temperature of the ultrasound is preferably 20-30° C., more preferably 25° C.; the time of the ultrasound is preferably 3-10 minutes, more preferably 5-8 minutes.

After the ultrasound is completed, the present invention performs a hydrothermal reaction on the mixture obtained by ultrasound to obtain a precursor. In the present invention, the hydrothermal reaction refers to a chemical reaction carried out in a sealed pressure vessel with water as a solvent under high temperature and high pressure conditions. In the present invention, the temperature of the hydrothermal reaction is 150-250°C, preferably 170-210°C, more preferably 180°C; the time of the hydrothermal reaction is preferably 1-24 hours, more preferably 8-24 hours 20 hours, most preferably 10 to 18 hours, most preferably 12 to 16 hours; the present invention has no special restrictions on the pressure of the hydrothermal reaction, as long as the temperature in the closed pressure vessel meets the above requirements . In the present invention, the hydrothermal reaction is preferably carried out in a reactor. In the present invention, the precursor obtained by the hydrothermal reaction has a hollow spherical structure, and the thickness of the hollow spherical shell is preferably 2-30 nm, more preferably 5-20 nm, and most preferably 10-15 nm.

After the hydrothermal reaction is completed, the present invention preferably dries the obtained precursor to obtain a dried precursor. In the present invention, the drying temperature is preferably 60-100°C, more preferably 70-90°C, most preferably 80°C; the drying time is preferably 8-12 hours, more preferably 10-11 hours .

After the precursor is obtained, the present invention mixes the metal catalyst with the obtained precursor to obtain the precursor containing the metal catalyst. In the present invention, the metal catalyst preferably includes one or more of iron salt, ferrous salt, nickel salt and cobalt salt, more preferably iron chloride, nickel chloride, nickel acetate, iron acetate, iron sulfate One or more of nickel sulfate, potassium ferricyanide and potassium ferrocyanide, most preferably one or more of nickel chloride, ferric chloride, potassium ferricyanide and nickel acetate; The mass ratio of the metal catalyst to the precursor is preferably (0.01˜1):1. In the present invention, the metal catalyst solution is preferably mixed with the precursor to obtain the precursor containing the metal catalyst. In the present invention, the molar concentration of the metal catalyst solution is preferably 0.01-0.1 mol/L, more preferably 0.05-0.08 mol/L.

In the present invention, the precursor is preferably immersed in the metal catalyst solution so that the metal catalyst is bound to the precursor. In the present invention, the metal catalyst is mainly combined with the precursor by deposition , and at the same time, some metal catalysts are combined with the precursor through the adsorption between functional groups. In the present invention, the soaking time is preferably 1-10 hours, more preferably 2-8 hours. After the above impregnation is completed, the present invention preferably filters the impregnated solution to remove the liquid and obtain a solid. In the present invention, the filtration is a method well known to those skilled in the art.

After the filtration is completed, in the present invention, the solid obtained by the filtration is preferably dried to obtain a dry precursor containing the metal catalyst. In the present invention, the drying temperature of the solid obtained by the filtration is preferably 60-100°C, more preferably 70-90°C, most preferably 80°C; the drying time of the solid obtained by the filtration is preferably 8 to 12 hours, more preferably 10 to 11 hours.

After the precursor containing the metal catalyst is obtained, the present invention heats the precursor containing the metal catalyst to obtain graphene. In the present invention, the precursor containing the metal catalyst is preferably mixed with a pore-forming agent and heated to obtain graphene. In the present invention, the pore-forming agent preferably includes one or more of water vapor, potassium hydroxide, potassium oxide, zinc chloride, phosphoric acid, sodium oxide, and sodium hydroxide, more preferably includes sodium hydroxide, hydrogen One or more of potassium oxide and water vapor, most preferably potassium hydroxide; the mass ratio of the pore-forming agent to the precursor containing the metal catalyst is preferably (1 to 5): 1, more preferably 2:1.

In the present invention, after mixing the pore-forming agent and the precursor containing the metal catalyst, it is preferred to dry first and then heat to obtain graphene. In the present invention, the drying of the pore-forming agent and the precursor mixture containing the metal catalyst is a method well known to those skilled in the art.

In the present invention, the mixture of the pore-forming agent and the precursor containing the metal catalyst is preferably heated under a protective gas atmosphere to obtain graphene. In the present invention, the protective gas is preferably an inert gas and/or nitrogen. In the present invention, the heating temperature is preferably 800-1200°C, more preferably 900-1100°C, most preferably 1000°C; the heating time is preferably 1-5 hours, more preferably 2-4 hours . In the present invention, the above-mentioned heating temperature is preferably achieved by raising the temperature, and the heating rate is preferably 3-8°C/min, more preferably 4-6°C/min, and most preferably 5°C/min.

After the heating is completed, in the present invention, the product obtained by heating is preferably acid-washed and filtered in order to remove the residual metal catalyst therein. In the present invention, the acid solution used in the pickling is preferably one or both of hydrochloric acid, sulfuric acid and nitric acid, and the immersion time of the pickling is preferably 0.5 to 8 hours, more preferably 1 to 7 hours, Most preferably, it is 2 to 6 hours.

After the pickling is completed, in the present invention, the pickled product is preferably subjected to solid-liquid separation, and the liquid is removed to obtain graphene. In the present invention, the solid-liquid separation is preferably filtration, which is a commonly used technical means by those skilled in the art.

After the solid-liquid separation is completed, in the present invention, the product obtained by the solid-liquid separation is preferably dried to obtain graphene. In the present invention, the drying is preferably drying, and the drying temperature is preferably 100-150°C, more preferably 90-140°C, most preferably 100-120°C; the drying time is preferably 8 to 12 hours, more preferably 10 hours.

The specific surface area of the graphene obtained according to the above preparation method is preferably 1000-2000 cm ³ /g, more preferably 1200-1800 cm ³ /g; the pore diameter of the graphene is preferably 1-10 nm, more preferably 2-9 nm, most preferably Preferably it is 3 to 8 nm.

After obtaining graphene, the present invention has carried out scanning electron microscope detection (SEM) to graphene, the result shows, graphene provided by the present invention is lamellar appearance, degree of graphitization is higher, and graphene surface distribution has a large amount of micropores .

The present invention uses a fully automatic specific surface area and microporous physical adsorption analyzer to detect the specific surface area and porosity of the graphene obtained in the present invention. The results show that the specific surface of the obtained porous graphene is relatively large, at 1000-2000cm ³ /g; The pore distribution is mainly 1-10nm.

The present invention carries out Raman spectrum detection on the obtained graphene, and the result shows that the obtained porous graphene has a certain degree of graphitization.

The invention provides a method for preparing graphene, comprising the following steps: A) mixing biomass materials, anionic surfactants and water, performing a hydrothermal reaction to obtain a precursor, and the temperature of the hydrothermal reaction is 150- 250°C, the time of the hydrothermal reaction is 1 to 24 hours; B) mixing the metal catalyst with the precursor obtained in the step A) to obtain a precursor containing the metal catalyst; C) the step B) obtained The precursor containing the metal catalyst is heated to obtain graphene. The preparation method provided by the present invention uses biomass material as a carbon source, and the reaction of biomass material under hydrothermal conditions can produce gas phase products, such as CO ₂ , CO and H ₂ , etc., and the anionic surfactant can enrich these bubbles With the biomass material in the bulk solution, and form carbon hollow spheres with bubbles as a template, the obtained carbon hollow spheres have a thin shell and are rich in a large amount of anionic surfactants, which dissociate into negatively charged in aqueous solution group, it is easier to adsorb positively charged metal ions such as iron and nickel, and carbon hollow spheres are more likely to be catalyzed by metal catalysts in the subsequent heating process to obtain graphene with a higher degree of graphitization.

Further, the present invention can also carry out fluorination treatment in the hydrothermal process, and carry out fluorination modification on the obtained carbon hollow spheres, so that the carbon hollow spheres have stronger electronegativity, which is more conducive to the adsorption of positively charged metals particle.

In order to further illustrate the present invention, a method for preparing graphene provided by the present invention will be described in detail below in conjunction with examples, but it should not be construed as limiting the protection scope of the present invention.

Example 1

Take 10g of glucose and 1g of sodium lauryl sulfate, add it to 150ml of hydrofluoric acid aqueous solution with a concentration of 0.01mol/l, then ultrasonicate the obtained glucose solution for 5 minutes, pour it into a reaction kettle, and carry out hydrothermal treatment at 180°C After reacting for 10 hours, dry at 80°C to obtain a precursor.

Take 1g of precursor, add it to 100ml of solution containing 1g of potassium ferricyanide, ultrasonicate for 15 minutes, let stand for 4h, filter, and dry the filtered solid at 80°C to obtain iron ion-containing precursor. According to the mass ratio of iron ion-containing precursor to KOH, it is mixed with KOH at a ratio of 1:1, dried, and calcined at 1000°C for 2h under an inert atmosphere with a heating rate of 5°C/min. Wash with hydrochloric acid, filter, and dry the filtered solid at 120°C to obtain porous graphene.

The present invention has carried out transmission electron microscope detection (TEM) to the precursor obtained in this embodiment, and the result is as shown in Figure 1, and Figure 1 is the TEM figure of the precursor obtained in Example 1 of the present invention; As can be seen from Figure 1, this embodiment The precursor obtained in the example is a hollow sphere structure with a thickness of 2-30nm.

The present invention has carried out scanning electron microscope detection (SEM) to the graphene that the present embodiment obtains, and the result is as shown in Figure 2, and Fig. 2 is the SEM figure of the porous graphene that the embodiment of the present invention 1 obtains;

The present invention has carried out transmission electron microscope detection (TEM) to the graphene obtained in the present embodiment, and the result is as shown in Figure 3, and Figure 3 is the TEM figure of the graphene obtained in Embodiment 1 of the present invention. It can be seen from FIG. 2 and FIG. 3 that the graphene material obtained in Example 1 of the present invention has a three-dimensional sheet morphology, and a large number of micropores are distributed on the surface of the porous graphene, and the size is mainly 1-10 nm.

The present invention has tested the specific surface area of the graphene obtained in the present embodiment according to the above-mentioned technical scheme, and the result is as shown in Figure 4, and Figure 4 is a graph of the specific surface area of the graphene obtained in Example 1 of the present invention. It can be seen from Figure 4 that the obtained graphene has a larger specific surface area, between 1000 and 2000 cm3/g.

The present invention tests the porosity of the graphene obtained in the present embodiment according to the above-mentioned technical scheme, and the result is shown in Figure 5, which is a graph of the graphene obtained in Example 1 of the present invention. It can be seen from Figure 5 that the pore distribution is mainly 1-10nm.

The present invention has carried out Raman spectrum (Raman) detection to the graphene obtained in this embodiment, and the result is shown in Figure 6, and Figure 6 is the Raman spectrum of the graphene obtained in Example 1 of the present invention. It can be seen from Figure 6 that the obtained graphene has a certain degree of graphitization.

Example 2

Take 20g of glucose and 1g of sodium dodecylbenzenesulfonate, add 150ml of deionized water, then ultrasonicate the resulting glucose solution for 5 minutes, pour it into a reaction kettle, and carry out hydrothermal reaction at 150°C. After 6 hours of reaction, 80 °C drying to obtain the precursor.

Take 1 g of the precursor, add it to 100 ml of a solution containing 0.5 g of ferric chloride, ultrasonicate for 15 minutes, let stand for 10 h, filter, and dry the filtered solid at 80° C. to obtain a precursor containing iron ions. Calcined at 800°C for 2 hours under an inert atmosphere with a heating rate of 5°C/min. The calcined product was washed with 1 mol/L hydrochloric acid, filtered, and the filtered solid was dried at 120°C to obtain graphene.

The present invention has carried out scanning electron microscope detection (SEM) to the precursor obtained in this embodiment, and the result is as shown in Figure 7, and Figure 7 is the SEM figure of the precursor obtained in Example 2 of the present invention; As can be seen from Figure 7, this embodiment The precursor obtained in this example has a lamellar structure.

Example 3

Take 50g of sucrose and 1g of sodium lauryl sulfate, add 300ml of deionized water, then ultrasonicate the obtained sucrose solution for 5 minutes, pour it into a reaction kettle, and carry out hydrothermal reaction at 250°C. After 24 hours of reaction, dry at 80°C , to obtain the precursor.

Take 1 g of the precursor, add it to 100 ml of nickel chloride solution containing 0.8 g, ultrasonicate for 15 minutes, let stand for 4 hours, filter, and dry the filtered solid at 80 ° C to obtain a precursor containing nickel ions. According to the ratio of the mass ratio of nickel ion-containing precursor to KOH of 1:3, mix it with KOH, dry it, and calcinate it at 1200°C for 2 hours under an inert atmosphere with a heating rate of 5°C/min. Wash with hydrochloric acid, filter, and dry the filtered solid at 120°C to obtain porous graphene.

Example 4

Take 30g of glucose and 1g of sodium dodecylsulfonate, add it to 300ml of hydrofluoric acid aqueous solution with a concentration of 0.01mol/l, then ultrasonicate the obtained glucose solution for 5 minutes, pour it into a reaction kettle, and carry out water treatment at 250°C. Heat reaction, after 1 hour of reaction, dry at 80°C to obtain the precursor.

Take 1 g of the precursor, add it to 100 ml of potassium ferricyanide solution containing 0.4 g, ultrasonicate for 15 minutes, let stand for 4 hours, filter, and dry the filtered solid at 80° C. to obtain a precursor containing iron ions. According to the mass ratio of the iron ion-containing precursor to KOH, it is mixed with KOH at a ratio of 1:2, dried, and calcined at 1000°C for 2h under an inert atmosphere, with a heating rate of 5°C/min. The calcined product is treated with 1mol/L Wash with hydrochloric acid, filter, and dry the filtered solid at 120° C. to obtain graphene.

Example 5

Take 40g of mannose and 1g of sodium dodecylbenzenesulfonate, add it to 300ml of hydrofluoric acid aqueous solution with a concentration of 2mol/l, then ultrasonicate the obtained mannose solution for 5 minutes, pour it into a reaction kettle, and heat it at 200°C Carry out hydrothermal reaction, after reacting for 5 hours, dry at 60°C to obtain the precursor.

Take 1g of the precursor, add it to 100ml of potassium ferricyanide solution containing 1g, sonicate for 15 minutes, let it stand for 4h, filter, and dry the filtered solid at 80°C to obtain a precursor containing iron ions. According to the mass ratio of iron ion-containing precursor to KOH, it is mixed with KOH, dried, and calcined at 1000°C for 2h under an inert atmosphere with a heating rate of 5°C/min. The calcined product is treated with 1mol/L Wash with hydrochloric acid, filter, and dry the filtered solid at 120°C to obtain porous graphene.

Example 6

Take 10g of glucose and 1g of sodium lauryl sulfate, add it to 300ml of hydrofluoric acid aqueous solution with a concentration of 1mol/l, then ultrasonicate the obtained glucose solution for 5 minutes, pour it into a reaction kettle, and carry out hydrothermal reaction at 170°C , after reacting for 16h, drying at 80°C to obtain the precursor.

Take 1 g of the precursor, add it to 100 ml of potassium ferricyanide solution containing 0.01 g, ultrasonicate for 15 minutes, let stand for 4 hours, filter, and dry the filtered solid at 80° C. to obtain a precursor containing iron ions. According to the mass ratio of iron ion-containing precursor to KOH, it is mixed with KOH at a mass ratio of 1:1, dried, and calcined at 900°C for 1h under an inert atmosphere with a heating rate of 5°C/min. Wash with hydrochloric acid, filter, and dry the filtered solid at 120°C to obtain porous graphene.

Comparative example 1

Take 10g of glucose, add 150ml of deionized water, sonicate the obtained glucose solution for 5 minutes, then pour it into the reaction kettle, and carry out hydrothermal reaction at 180°C. After reacting for 12h, the reaction solution is dried at 80°C to obtain the precursor.

Take 1 g of the precursor, add it to 100 mL of potassium ferricyanide solution containing 1 g, ultrasonicate for 15 minutes, let it stand for 4 hours, filter, and dry the filtered solid at 80 ° C to obtain a precursor containing iron ions. Mix with KOH at a mass ratio of 1:1, dry and calcinate at 1000°C for 2 hours under a nitrogen atmosphere with a heating rate of 5°C/min, wash the calcined product with 1mol/L hydrochloric acid, filter, and dry at 120°C to obtain graphite alkene.

The present invention has carried out transmission electron microscope detection (TEM) to the precursor that this comparative example obtains, and the result is as shown in Figure 8, and Figure 8 is the TEM figure of the precursor that Comparative Example 1 of the present invention obtains; As can be seen from Figure 8, this comparison The precursor obtained in this example has a solid spherical structure.

The present invention has carried out scanning electron microscope detection (SEM) to the graphene that the present comparative example obtains, and the result is as shown in Figure 9, and Fig. 9 is the SEM figure of the graphene that comparative example 1 of the present invention obtains;

The present invention has carried out transmission electron microscope detection (TEM) to the graphene obtained in this comparative example, and the result is shown in Figure 10, and Figure 10 is the TEM figure of the graphene obtained in Comparative Example 1 of the present invention. It can be seen from FIG. 9 and FIG. 10 that the graphene material obtained in Comparative Example 1 of the present invention has a wrinkled sheet morphology, but the sheet is thicker and the degree of graphitization is lower.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (7)

1. a preparation method of graphene, comprising the following steps: A) Mixing biomass material, anionic surfactant, hydrofluoric acid and water, and performing a hydrothermal reaction to obtain a precursor, the temperature of the hydrothermal reaction is 150-250°C, and the time of the hydrothermal reaction is 1 ~24 hours; the molar concentration of the hydrofluoric acid is 0.01~2mol/L; the biomass material includes one or more of glucose, sucrose, fructose, sorbose, galactose, and mannose; B) mixing the metal catalyst with the precursor obtained in step A) to obtain a precursor containing the metal catalyst; the metal catalyst includes one or more of iron salts, ferrous salts, nickel salts and cobalt salts; C) heating the metal catalyst-containing precursor obtained in step B) to obtain graphene. 2. preparation method according to claim 1, is characterized in that, described anion surfactant comprises sodium lauryl sulfate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate and stearic acid One or more of sodium. 3. The preparation method according to claim 1, characterized in that, the mass ratio of the biomass material to the anionic surfactant is (10-50):1. 4. The preparation method according to claim 1, characterized in that the mass ratio of the metal catalyst to the precursor obtained in step A) is (0.01-1):1. 5. The preparation method according to claim 1, characterized in that, the heating temperature in the step C) is 800-1200°C; The heating time is 1-5 hours. 6 . The preparation method according to claim 1 , wherein the precursor obtained in step A) has a hollow spherical structure, and the thickness of the hollow spherical shell is 2-30 nm. 7. The preparation method according to any one of claims 1 to 6, wherein the step C) specifically comprises: mixing the pore-forming agent with the metal catalyst-containing precursor obtained in the step B), and performing heating to obtain graphene; The pore forming agent includes one or more of water vapor, potassium hydroxide, potassium oxide, zinc chloride, phosphoric acid, sodium oxide and sodium hydroxide; The mass ratio of the pore forming agent to the biomass material in the step A) is (1-5):1.