CN104817080B - A kind of preparation method of nitrogen sulfur phosphorus doping graphene film - Google Patents

Abstract

The invention discloses a method for preparing graphene sheet doped with nitrogen, sulfur and phosphorus. The specific steps are as follows: adding hydrotalcite to an appropriate amount of tetramethylammonium bromide solution, stirring and aging, and then adding dimethyl sulfoxide and orthophosphate Butyl ester, stirred in a constant temperature water bath at 60-70°C for 6-8 hours, separated the precipitate from the liquid, washed the precipitate 2-3 times with deionized water, dried, ground, and passed through a 20-40 mesh sieve to obtain modified water Talc powder: put the obtained powder into a vacuum tube furnace, heat it to 400-600°C under vacuum, calcinate it for 2-4 hours, then add it to the hydrofluoric acid solution, separate the precipitate, and then heat it to After heat treatment at 2000-2500°C for 3-6 hours, nitrogen-sulfur-phosphorus-doped graphene sheets can be obtained after cooling. The method has simple materials and mild conditions.

Description

A kind of preparation method of nitrogen sulfur phosphorus doped graphene sheet

technical field

The invention belongs to the technical field of nanomaterial preparation, in particular to a preparation method of nitrogen, sulfur and phosphorus doped graphene sheets.

Background technique

In the research and development of new materials, dimensionality has become an important parameter for modulating the structure and properties of matter. When the material changes from three-dimensional structure to two-dimensional, one-dimensional and zero-dimensional, its geometric structure and physical and chemical properties will change significantly. Two-dimensional nanomaterials have been widely used in many fields such as solid-state nanodevices, sensing and functional thin films due to their anisotropy and unique optoelectronic properties. In particular, highly oriented graphitic carbon 001 has a unique resistance to radiation, which is expected to be used in medical low-energy neutron radiation-resistant materials, X-Ray monochromator radiation-resistant materials, and nuclear fusion reactor radiation-resistant materials. It will become an advanced A new anti-radiation material in the field of science and technology.

As a two-dimensional material, the general thickness direction is monoatomic layer or diatomic layer carbon atoms. The discovery of graphene broke the theoretical inference that two-dimensional single-layer atomic crystals cannot exist, and triggered the current research boom on two-dimensional single-atom layer materials. This not only becomes one of the important sources of new knowledge in the field of nanoscience, but also provides an opportunity for the development of high-performance functional nanomaterials and devices. One of the current research hotspots in this field is the functional modification of single atomic layer materials. With the deepening of research, the demand for two-dimensional nanomaterials is gradually increasing, and there is an urgent need for simple and feasible synthesis methods.

However, due to the high surface free energy of two-dimensional nanomaterials, unconventional methods are often used in the preparation process. For example, high-quality and large-area graphene two-dimensional nanomaterials can be prepared by CVD, but the ideal substrate material single crystal The price of nickel is too expensive, which is an important factor affecting the industrial production of graphene. In addition, the cost is high and the process is complicated. In addition, there is an oxidation-reduction method, the disadvantage of which is that the macro-preparation is easy to cause waste liquid pollution and the prepared graphene has certain defects, for example, topological defects such as five-membered rings and seven-membered rings or structures with -OH groups These defects will lead to the loss of some electrical properties of graphene, which will limit the application of graphene.

One of the current research hotspots in the field of graphene is the functional modification of single atomic layer materials. People have always dreamed of regularly and discretely introducing metal atoms into these single atomic layer materials to form new single atomic layer magnetic materials, catalytic materials and gas adsorption materials, but this dream has not been possible due to the easy aggregation of transition metal atoms. Realized in graphene and monatomic layers.

Semiconductors can be doped, and the energy bands of semiconductors after doping will be changed. Depending on the dopant, different energy levels appear between the energy gaps of the intrinsic semiconductor. The donor atom creates a new energy level close to the conduction band, while the acceptor atom creates a new energy level close to the valence band. Another significant effect of dopants on the band structure is to change the position of the Fermi level. In the state of thermal equilibrium, the Fermi level will remain constant, and this property will lead to many other useful electrical properties.

The general chemical structure formula of bentonite is: [M ²⁺ _1-x M ³⁺ x(OH) ₂ ] ^x+ [(A ^n- ) _x/n mH ₂ O], where M ²⁺ is Mg ²⁺ , Ni ^{2 +} , Mn ²⁺ , Zn ²⁺ , Ca ²⁺ , Fe ²⁺ , Cu ²⁺ and other divalent metal cations; M ³⁺ is Al ³⁺ , Cr ³⁺ , Fe ³⁺ , Co ³⁺ and other trivalent metal cations Cation; ^An- is an anion, such as CO ₃ ^2- , NO ₃ ^- , Cl ^- , OH ^- , SO ₄ ^2- , PO ₄ ^3- , C ₆ H ₄ (COO) ₂ ^2- and other inorganic and organic ions and Complex ions, when the inorganic cations between layers are different, the interlayer spacing of bentonite is different.

Contents of the invention

The purpose of the present invention is to provide a method for preparing graphene sheets doped with nitrogen, sulfur and phosphorus in order to overcome the deficiencies in the prior art such as complicated preparation process and high price.

For this reason, the invention provides following technical scheme, a kind of preparation method of nitrogen sulfur phosphorus doped graphene sheet, comprises the following steps successively:

1) According to the amount of 0.5-1 mmol tetramethylammonium bromide per gram of hydrotalcite, add hydrotalcite that has passed through a 20-50 mesh sieve into a tetramethylammonium bromide solution with a concentration of 0.1% to 1% by mass , stirring in a constant temperature water bath at 60-70°C for 5-6 hours, and aging for 12-24 hours to obtain tetramethylammonium bromide-modified hydrotalcite suspension;

2) Add dimethyl sulfoxide and n-butyl phosphate to tetramethylammonium bromide-modified dimethyl sulfoxide and 2-4 mmol of n-butyl phosphate according to the corresponding amount of 1-3 mmol per gram of hydrotalcite. In the hydrotalcite suspension, stir in a constant temperature water bath at 60-70°C for 6-8 hours, separate the precipitate from the liquid, wash the precipitate with deionized water 2-3 times, dry, grind, and pass through a 20-40 mesh sieve Obtain modified hydrotalcite powder;

3) Put the obtained modified hydrotalcite powder into a vacuum tube furnace, heat to 400-600°C under vacuum conditions, vacuum calcinate for 2-4 hours, and cool to room temperature;

4) Add the calcined powder to a hydrofluoric acid solution with a mass percentage concentration of 20% to 40%, each gram of powder corresponds to 5 to 10 milliliters of hydrofluoric acid solution, stir for 3 to 4 hours under nitrogen protection, and precipitate and separate, drying;

5) Heating the obtained product to 2000-2500° C. under vacuum conditions, heat-treating for 3-6 hours, and obtaining nitrogen-sulfur-phosphorus-doped graphene sheets after cooling.

Compared with the prior art, the present invention has the following beneficial technical effects:

1. The source of the nanomaterial is simple. The common cationic surfactant tetramethylammonium bromide is used to exchange tetramethylammonium bromide into the hydrotalcite layer through cation exchange, and then use the distribution of organic matter. Adsorb dimethyl sulfoxide and n-butyl phosphate to the interlayer of hydrotalcite, and the phosphorus and sulfur atoms can be evenly distributed among the organic matter. After drying, carbonization and exfoliation, a sheet carbon material with nanoscale can be prepared. .

2. Utilize the special structure of hydrotalcite to ensure that the interlayer organic matter is dispersed in one or two layers of single molecules, and forms a two-dimensional polymeric aromatic carbon structure after carbonization at 400-600 °C.

3. After the carbonized material is pickled, the structure of the hydrotalcite itself is destroyed, the magnesium aluminum oxide is dissolved by the acid, and the carbonaceous material between the layers is naturally peeled off. The process is simple and gentle.

4. The nitrogen, sulfur and phosphorus doped graphene sheets after heat treatment can still maintain the original interlayer thickness.

detailed description

The present invention will be described in detail below in conjunction with the examples, but the present invention is not limited thereto.

Example 1

According to the amount of 0.5mmol tetramethylammonium bromide per gram of hydrotalcite, the commercially available magnesium aluminum hydrotalcite passing through a 20-mesh sieve is added to the tetramethylammonium bromide solution with a mass percentage concentration of 0.1%. Stir in a constant temperature water bath for 5 hours, and age for 12 hours to obtain a hydrotalcite suspension modified by tetramethylammonium bromide; Add methyl sulfoxide and n-butyl phosphate to tetramethylammonium bromide-modified hydrotalcite suspension, stir in a constant temperature water bath at 60°C for 6 hours, separate the precipitate from the liquid, and wash the precipitate with deionized water 2 times, dry, grind, and pass through a 20-mesh sieve to obtain modified hydrotalcite powder; put the obtained modified hydrotalcite powder into a vacuum tube furnace, heat to 400°C under vacuum conditions, vacuum calcine for 2 hours, and cool to room temperature ; The calcined powder is added to a hydrofluoric acid solution with a mass percentage concentration of 20%, and each gram of powder corresponds to 5 milliliters of hydrofluoric acid solution, stirred for 3 hours under nitrogen protection, precipitated and separated, and dried; Under vacuum conditions, heat to 2000°C, heat-treat for 3 hours, and obtain nitrogen-sulfur-phosphorus-doped graphene sheets after cooling.

Example 2

According to the amount of 1 mmol tetramethylammonium bromide per gram of hydrotalcite, commercially available nickel-aluminum hydrotalcite passing through a 50-mesh sieve is added to a tetramethylammonium bromide solution with a concentration of 1% by mass, and kept at a constant temperature of 70°C Stir in a water bath for 6 hours, and age for 24 hours to obtain a hydrotalcite suspension modified by tetramethylammonium bromide; Add sulfoxide and n-butyl phosphate to tetramethylammonium bromide-modified hydrotalcite suspension, stir in a constant temperature water bath at 70°C for 8 hours, separate the precipitate from the liquid, and wash the precipitate with deionized water 3 drying, grinding, and passing through a 40-mesh sieve to obtain modified hydrotalcite powder; put the obtained modified hydrotalcite powder into a vacuum tube furnace, heat to 600°C under vacuum conditions, vacuum calcinate for 4 hours, and cool to room temperature; Add the calcined powder to a hydrofluoric acid solution with a concentration of 40% by mass, each gram of powder corresponds to 10 milliliters of hydrofluoric acid solution, stir for 4 hours under nitrogen protection, precipitate and separate, and dry; Under the conditions, heating to 2500°C, heat treatment for 6h, and cooling to obtain nitrogen, sulfur, and phosphorus doped graphene sheets.

Example 3

According to the amount of 1 mmol of tetramethylammonium bromide per gram of hydrotalcite, the hydrotalcite passing through a 20-mesh sieve is added to the tetramethylammonium bromide solution with a concentration of 0.5% by mass, and stirred in a constant temperature water bath at 60°C for 6 hours , aging for 24h to obtain tetramethylammonium bromide-modified hydrotalcite suspension; then according to the corresponding amount of 2mmol of dimethyl sulfoxide and 3mmol of n-butyl phosphate per gram of hydrotalcite, dimethyl sulfoxide and phosphoric acid Add n-butyl ester to tetramethylammonium bromide-modified hydrotalcite suspension, stir in a constant temperature water bath at 70°C for 8 hours, separate the precipitate from the liquid, wash the precipitate 3 times with deionized water, and dry , ground, and passed through a 40-mesh sieve to obtain modified hydrotalcite powder; put the obtained modified hydrotalcite powder into a vacuum tube furnace, heat to 500 °C under vacuum conditions, vacuum calcined for 4 hours, and cooled to room temperature; the calcined The powder is added to a hydrofluoric acid solution with a concentration of 40% by mass, and each gram of powder corresponds to 10 milliliters of hydrofluoric acid solution, stirred for 4 hours under nitrogen protection, precipitated and separated, and dried; the obtained product is heated under vacuum conditions After heat treatment at 2500°C for 5 hours, nitrogen, sulfur, and phosphorus doped graphene sheets can be obtained after cooling.

Claims (1)

1. a preparation method of nitrogen sulfur phosphorus doped graphene sheet, is characterized in that: comprise the steps successively: 1) According to the amount of 0.5-1 mmol tetramethylammonium bromide per gram of hydrotalcite, add hydrotalcite that has passed through a 20-50 mesh sieve into a tetramethylammonium bromide solution with a concentration of 0.1% to 1% by mass , stirring in a constant temperature water bath at 60-70°C for 5-6 hours, and aging for 12-24 hours to obtain tetramethylammonium bromide-modified hydrotalcite suspension; 2) Add dimethyl sulfoxide and n-butyl phosphate to tetramethylammonium bromide-modified dimethyl sulfoxide and 2-4 mmol n-butyl phosphate according to the corresponding amount of 1-3 mmol per gram of hydrotalcite. In the hydrotalcite suspension, stir in a constant temperature water bath at 60-70°C for 6-8 hours, separate the precipitate from the liquid, wash the precipitate with deionized water 2-3 times, dry, grind, and pass through a 20-40 mesh sieve Obtain modified hydrotalcite powder; 3) Put the obtained modified hydrotalcite powder into a vacuum tube furnace, heat to 400-600°C under vacuum conditions, vacuum calcinate for 2-4 hours, and cool to room temperature; 4) Add the calcined powder to a hydrofluoric acid solution with a mass percentage concentration of 20% to 40%, each gram of powder corresponds to 5 to 10 milliliters of hydrofluoric acid solution, stir for 3 to 4 hours under nitrogen protection, and precipitate and separate, drying; 5) Heating the obtained product to 2000-2500° C. under vacuum conditions, heat-treating for 3-6 hours, and obtaining nitrogen-sulfur-phosphorus-doped graphene sheets after cooling.