CN105280900A - Tungsten disulfide/graphene nanobelt composite material and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of transition metal sulfide-carbon materials, and specifically relates to a tungsten disulfide/graphene nanobelt composite material and a preparation method thereof. The graphene nanobelts of the present invention are prepared by a solution oxidation method, and the tungsten disulfide/graphene nanobelt composite material is grown in situ on the graphene nanobelts by a one-step solvothermal method. The graphene nanobelt prepared by the present invention has the advantages of stable chemical properties and good electrical conductivity; the composite material prepared by the present invention has the characteristics of controllable morphology, and the tungsten disulfide nanosheet is evenly loaded on the graphene nanobelt, effectively The agglomeration of tungsten disulfide itself is effectively suppressed, and the unique high specific surface area and high conductivity of graphene nanoribbons are fully utilized. The tungsten disulfide/graphene nanoribbon composite material prepared by the invention can be an ideal high-performance electrocatalytic material and an electrode material for new energy devices such as lithium ion batteries and solar batteries.

Description

A kind of tungsten disulfide/graphene nanobelt composite material and preparation method thereof

technical field

The invention belongs to the technical field of transition metal sulfide-carbon materials, and specifically relates to a tungsten disulfide/graphene nanobelt composite material and a preparation method thereof.

technical background

Graphene nanoribbons are quasi-one-dimensional carbon-based nanomaterials, which have many excellent physical and chemical properties, such as high electrical conductivity, excellent mechanical properties, special edge effects, and good chemical stability. These special properties make it have extremely broad application prospects in the fields of energy conversion and storage, electronic sensors, polymer nanocomposites, etc., and become one of the research hotspots in the field of carbon nanomaterials.

Tungsten disulfide is a typical transition metal chalcogenide. It belongs to the hexagonal crystal system. There are strong S-W-S covalent bonds in the layer and weak van der Waals force between the layers. The thickness of the single layer is about 0.65nm. Single-layer tungsten disulfide nanosheets can be obtained by tape stripping or lithium ion intercalation. Studies have shown that the exposed active edge of tungsten disulfide has hydrogen evolution catalytic activity, so it has a wide range of applications in the field of electrochemical catalysis. However, pure tungsten disulfide is easy to agglomerate, and it preferentially grows the inert inner layer structure instead of the active sheet edge, and a large number of agglomerates further inhibits the exposure of the active edge, coupled with its poor conductivity, pure The excellent properties of tungsten disulfide will not be fully utilized. Therefore, it is of great significance to combine tungsten disulfide with other highly conductive substrate materials.

The invention prepares a novel tungsten disulfide/graphene nanobelt composite material through simple process design. The composite material has the following advantages: the unique edge effect of graphene nanoribbons can provide more growth sites for the growth of tungsten disulfide nanosheets, so that the active edges of tungsten disulfide nanosheets can be more fully exposed; The excellent conductivity of the ribbon is conducive to the transmission of electrons, which can improve the overall conductivity of the composite material; the thin layer structure of the graphene nanoribbon is conducive to the migration of electrolyte ions in the electrochemical process, thereby reducing its contact internal resistance with the solution. The tungsten disulfide nanosheet itself has excellent catalytic activity and energy storage performance, so the effective combination of the two can achieve good synergy to prepare a composite material with excellent performance.

Contents of the invention

The object of the present invention is to provide a tungsten disulfide/graphene nanoribbon composite material with excellent electrochemical performance and a preparation method thereof.

The tungsten disulfide/graphene nanobelt composite material provided by the present invention consists of graphene nanobelts with special band edges and ammonium thiotungstate grown in situ on the graphene nanobelts by a one-step solvothermal method Composed of tungsten disulfide nanosheets; its preparation raw materials include: carbon nanotubes (single-wall or multi-wall), potassium permanganate, concentrated sulfuric acid, phosphoric acid, ammonium thiotungstate, and hydrazine hydrate.

The preparation method of the tungsten disulfide/graphene nanoribbon composite material provided by the present invention is to prepare the graphene nanoribbon through the solution oxidation method; and then grow the tungsten disulfide nanosheet in situ on the graphene nanoribbon by one-step solvothermal method ;Specific steps are as follows:

(1) Disperse the carbon nanotubes in 95%~98% concentrated sulfuric acid, and then add a certain amount of 85% phosphoric acid after the dispersion is uniform. During this process, keep stirring to obtain a uniform dispersion;

(2) Add potassium permanganate to the above dispersion and keep stirring;

(3) Slowly raise the temperature of the reaction system. After the temperature is stable, keep it warm and keep stirring;

(4) The resulting mixed solution was naturally cooled to room temperature, then poured into ice water containing hydrogen peroxide, and left overnight to allow it to settle naturally;

(5) The obtained precipitate was washed several times with aqueous hydrochloric acid solution, and then washed several times with a mixed solution of ethanol/ether;

(6) Centrifugal drying to obtain solid graphene oxide nanobelts;

(7) Disperse graphene oxide nanoribbons in an organic solvent, and obtain a stable dispersion of graphene oxide nanoribbons by ultrasonication;

(8) Dissolve ammonium thiotungstate in the graphene oxide nanoribbon dispersion liquid, and disperse it uniformly by ultrasonic to obtain ammonium thiotungstate/graphene oxide nanoribbon dispersion liquid;

(9) Drop the hydrazine hydrate solution into the mixed dispersion of ammonium thiotungstate and graphene oxide nanoribbons, and disperse evenly by ultrasonic;

(10) Put the prepared dispersion liquid containing graphene oxide nanoribbons, ammonium thiotungstate and hydrazine hydrate into a hydrothermal kettle, heat the organic solvent for a period of time, and wash the prepared black precipitate with deionized water and Repeated washing with ethanol several times to obtain the tungsten disulfide/graphene nanoribbon composite material.

In the present invention, the graphene oxide nanoribbons are prepared by radially cutting carbon nanotubes by a solution oxidation method. For this method, refer to the patent US2010/0105834Al.

In the present invention, the organic solvent includes N,N -dimethylformamide, N,N -dimethylacetamide and N -methylpyrrolidone, preferably N,N -dimethylformamide.

In the present invention, the concentration of the carbon nanotubes in step (1) is 3-5 mgmL ^-1 , and the volume ratio of concentrated sulfuric acid to phosphoric acid is 8:1-10:1, preferably 9:1.

In the present invention, the quality of the potassium permanganate described in step (2) is 2 to 5 times the amount of carbon nanotubes, preferably adding potassium permanganate in batches.

In the present invention, the temperature reached after the temperature rise in step (3) is 60-80° C., and the holding time is 2-3 hours.

In the present invention, the weight concentration of the hydrochloric acid aqueous solution described in step (5) is 5-20%.

In the present invention, the concentration of the graphene oxide nanoribbon dispersion in step (7) is 0.5-2 mgmL ^-1 , preferably 1-1.5 mgmL ^-1 .

In the present invention, the mass ratio of the graphene oxide nanoribbons described in step (8) to ammonium thiotungstate is 1:1-1:4.

In the present invention, the concentration of the hydrazine hydrate described in step (9) is 30%-80%, and the dosage is 0.1-0.2mL.

In the present invention, the reaction temperature in step (10) is 220-260° C., and the reaction time is 10-24 hours.

Use transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffractometer (XRD) to characterize the structural morphology of the tungsten disulfide/graphene nanobelt composite material obtained in the present invention, the results are as follows:

(1) The TEM test results show that the boundary of the inner wall layer of the graphene nanoribbons disappears through the solution oxidation method, which confirms that the carbon nanotubes are cut open radially. The prepared graphene nanoribbons have a high aspect ratio and special band edges. Compared with the original carbon nanotubes, its size is increased, the bandwidth is about 100nm, and its higher specific surface area is tungsten disulfide nanosheets. The growth of provides more growth sites. See attached drawing 1. In the tungsten disulfide/graphene nanobelt composite material, tungsten disulfide nanosheets grow uniformly on the surface of graphene nanoribbons, and the number of tungsten disulfide nanosheets is less, about 5-10 layers, which is thinner The tungsten disulfide nanosheets provided more active edges, resulting in significantly improved catalytic activity and energy storage performance. See attached drawing 2.

(2) SEM test results show that: in the tungsten disulfide/graphene nanoribbon composite material, tungsten disulfide nanosheets grow uniformly on the graphene nanoribbons, which effectively inhibits the agglomeration of tungsten disulfide itself and makes disulfide The active edges of the tungsten nanosheets are fully exposed. This is due to the banded edge structure and high specific surface area of graphene nanoribbons, which endow it with more flexible and adjustable properties, which is also the main feature different from sheet graphene. See attached drawing 3.

(3) The XRD test results show that the prepared graphene oxide nanoribbons have a strong diffraction peak at 2θ=10°, indicating that the carbon nanotubes have been successfully exfoliated or cut into nanoribbon structures. The reduced graphene nanoribbons have a broad diffraction peak at 2θ=26°, corresponding to the (002) crystal plane. The as-prepared tungsten disulfide/graphene nanoribbon composites show the characteristic peaks of tungsten disulfide, and the diffraction peaks appear at 2θ=14°, 33°, 40° and 59°, corresponding to the (002 ), (101), (103) and (100) crystal planes. See attached drawing 4.

The advantages of the present invention are:

1. The preparation process is simple and easy to operate, which is a convenient and effective preparation method;

2. The experimental design is ingenious;

First, the chosen substrate is graphene nanoribbons. Its unique aspect ratio and edge structure endow it with a high specific surface area and provide more sites for the growth of tungsten disulfide nanosheets. Graphene nanobelts have excellent electrical conductivity, and their sheet structure enables fast and effective transport of electrons and ions during electrocatalysis, which can further improve the catalytic activity and energy storage performance of tungsten disulfide;

Second, the composite of quasi-one-dimensional materials and two-dimensional materials is realized through a simple solvothermal method, so that the advantages of the two can be fully utilized, thereby constructing composite materials with excellent properties.

The tungsten disulfide/graphene nanobelt composite material prepared by the invention can be used as a high-performance catalyst material and an ideal electrode material for new energy sources such as lithium ion batteries and solar batteries.

Description of drawings

Fig. 1 is a TEM image of the material in the present invention. Among them, (A) multi-walled carbon nanotubes, (B) graphene nanoribbons.

Figure 2 is a TEM image of the tungsten disulfide/graphene nanoribbon composite material of the present invention.

Fig. 3 is the SEM image of the tungsten disulfide/graphene nanoribbon composite material composite material of the present invention.

Fig. 4 is an XRD pattern of the tungsten disulfide/graphene nanoribbon composite material of the present invention.

detailed description

Below in conjunction with specific example, further set forth the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Embodiment 1, the present embodiment comprises the following steps:

(1) Disperse 150 mg of multi-walled carbon nanotubes in 98% concentrated sulfuric acid, and then add 85% phosphoric acid after the dispersion is uniform, and keep stirring during this process to obtain a uniform dispersion;

(2) Add 750mg potassium permanganate to the above dispersion, add in batches, and keep stirring;

(3) Slowly raise the temperature of the reaction system to 70°C. After the temperature is stable, keep it warm for a period of time and keep stirring;

(4) Cool the resulting mixed dispersion to room temperature naturally, then pour it into ice water containing 7mL of 50% hydrogen peroxide, and let it settle overnight;

(5) Wash the obtained precipitate several times with 10% hydrochloric acid aqueous solution, and then wash it several times with a mixed solution of ethanol/ether;

(6) Centrifugal drying to obtain solid graphene oxide nanobelts;

(7) Disperse the graphene oxide nanoribbons in N,N -dimethylformamide, and obtain a stably dispersed 1 mgmL ^-1 graphene oxide nanoribbons by ultrasonication;

(8) Dissolve 11 mg of ammonium thiotungstate in 10 mL of graphene oxide nanoribbon dispersion liquid, and disperse it evenly by ultrasonic;

(9) Drop 0.2mL of 50% hydrazine hydrate into the mixed dispersion of graphene oxide nanoribbons and ammonium thiotungstate, and disperse evenly by ultrasonic;

(10) Put the prepared dispersion containing graphene oxide nanoribbons, ammonium thiotungstate and hydrazine hydrate into a hydrothermal kettle, and conduct a hydrothermal reaction at 240°C for 12 hours, and wash the prepared black precipitate with deionized water and After repeated washing with ethanol for several times, the tungsten disulfide nanosheet/graphene nanoribbon composite material can be obtained, which is denoted as GNRWS ₂ -1 .

Example 2. Change the mass of ammonium thiotungstate in Example 1 to 22 mg, and the rest are the same as in Example 1. The finally obtained composite material is denoted as GNRWS ₂ -2.

Example 3. Change the mass of ammonium thiotungstate in Example 1 to 44 mg, and the rest are the same as in Example 1. The finally obtained composite material is recorded as GNRWS ₂ -3.

Claims (10)

1. a preparation method for tungsten disulfide/graphene nano belt composite, is characterized in that: prepare graphene nanobelt by solution oxide method; Again by step solvent-thermal method growth in situ tungsten disulfide nano slices on graphene nanobelt; Concrete steps are as follows:

(1) by carbon nanotube dispersed in the concentrated sulfuric acid of 95% ~ 98%, after being uniformly dispersed, adding the phosphoric acid of a certain amount of 85% again, in the process, constantly stirring and obtain homogeneous dispersion liquid;

(2) in above-mentioned dispersion liquid, potassium permanganate is added, Keep agitation;

(3) reaction system is slowly warmed up to 60 ~ 80 DEG C, after temperature stabilization, insulation 2 ~ 3h, and constantly stir;

(4) mixed solution of gained is naturally cooled to room temperature, then pour in the frozen water containing hydrogen peroxide, placement overnight, make its natural subsidence;

(5) the sediment aqueous hydrochloric acid solution obtained is washed repeatedly, then wash repeatedly with the mixed solution of ethanol/ether;

(6) centrifugal drying obtains solid oxidation graphene nanobelt;

(7) stannic oxide/graphene nano band is scattered in organic solvent, ultrasonicly obtains stannic oxide/graphene nano band stable dispersions;

(8) sulfo-ammonium tungstate is dissolved in stannic oxide/graphene nano band dispersion liquid, ultrasonicly makes it be uniformly dispersed, obtain sulfo-ammonium tungstate/stannic oxide/graphene nano band dispersion liquid;

(9) instilled by hydrazine hydrate solution in the mixed dispersion liquid of sulfo-ammonium tungstate and stannic oxide/graphene nano band, ultrasonic disperse is even;

(10) the prepared dispersion liquid containing stannic oxide/graphene nano band, sulfo-ammonium tungstate and hydrazine hydrate is put into water heating kettle, organic solvent thermal response, reaction temperature is 220 ~ 260 DEG C, reaction time is 10 ~ 24h, by the black precipitate deionized water for preparing and ethanol cyclic washing repeatedly, tungsten disulfide/graphene nano belt composite is namely obtained.

2. the preparation method of tungsten disulfide according to claim 1/graphene nano belt composite, is characterized in that, described organic solvent is n, N-dimethyl formamide, n, N-dimethylacetylamide or n-methyl pyrrolidone.

3. the preparation method of tungsten disulfide according to claim 1/graphene nano belt composite, is characterized in that, the concentration of the carbon nano-tube described in step (1) is 3 ~ 5mgmL ^-1, the volume ratio of the concentrated sulfuric acid and phosphoric acid is 8:1 ~ 10:1.

4. the preparation method of tungsten disulfide according to claim 1/graphene nano belt composite, is characterized in that, the quality of the potassium permanganate described in step (2) is 2 ~ 5 times of carbon nano-tube consumption.

5. the preparation method of tungsten disulfide according to claim 1/graphene nano belt composite, is characterized in that, the aqueous hydrochloric acid solution weight concentration described in step (5) is 5 ~ 20%.

6. the preparation method of tungsten disulfide according to claim 1/graphene nano belt composite, is characterized in that, the concentration of the stannic oxide/graphene nano band dispersion liquid described in step (7) is 0.5 ~ 2mgmL ^-1.

7. the preparation method of tungsten disulfide according to claim 1/graphene nano belt composite, is characterized in that, the mass ratio of the stannic oxide/graphene nano band described in step (8) and sulfo-ammonium tungstate is 1:1 ~ 1:4.

8. the preparation method of tungsten disulfide according to claim 1/graphene nano belt composite, is characterized in that, the concentration of hydrazine hydrate described in step (9) is 30% ~ 80%, and consumption is 0.1 ~ 0.2mL.

9. the tungsten disulfide that the preparation method as described in one of claim 1 ~ 8 prepares/graphene nano belt composite.

10. tungsten disulfide/graphene nano belt composite as claimed in claim 9 is as high-performance electric catalysis material, and the application of electrode material as lithium ion battery and solar cell.