CN108677048B - Nitrogen-doped graphene silver-based composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a nitrogen-doped graphene-silver-based composite material, and the invention discloses a nitrogen-doped graphene-silver-based composite material and a preparation method, including the following preparation steps. First, a graphene oxide dispersion is prepared, and urea is mixed Dissolved in graphene dispersion, then kept in a hydrothermal reactor for several hours, taken out and cooled to room temperature naturally, the product was washed, centrifuged and dried to obtain nitrogen-doped graphene powder. The nitrogen-doped graphene and the silver powder are mixed with an anhydrous ethanol solution, stirred and dried at 60-80° C. to obtain a composite powder of the nitrogen-doped graphene and the silver powder. The composite powder is ball-milled, three-dimensionally mixed, pressed and hot-pressed and sintered to finally obtain a nitrogen-doped graphene silver-based composite material. Through the above method, doping nitrogen atoms into graphene improves the conductivity of reduced graphene oxide, improves the distribution of graphene in the matrix and the interface between graphene and the metal matrix, and obtains nitrogen-doped nitrogen atoms with excellent comprehensive properties. Silver-based bulk composites of graphene.

Description

A kind of silver-based composite material of nitrogen-doped graphene and preparation method thereof

technical field

The invention belongs to the technical field of silver-based composite materials, in particular to a silver-based composite material with nitrogen-doped graphene, and also relates to a preparation method of the silver-based composite material.

Background technique

The materials prepared by metallic silver have low room temperature resistivity, good ductility, low resistance and excellent oxidation resistance. They are widely used in low-voltage electrical appliances, communication electronic instruments, household appliances, aerospace devices and other fields. A wide range of and at the same time the most economical precious metal materials. Although it has many excellent properties, it has shortcomings such as low strength.

Graphene is a new type of two-dimensional honeycomb-shaped nanomaterial composed of single-layer carbon atoms closely arranged. It has excellent electrical and thermal conductivity, high Young's modulus and hardness. It is the highest strength and thinnest material so far. The excellent properties of graphene have potential applications in supercapacitors, lithium-ion batteries, and nanocomposites, especially in the field of metal matrix composites. The introduction of graphene into the silver matrix can improve the strength of the silver matrix on the basis of maintaining the good electrical and thermal conductivity of the silver matrix, and it is expected to develop a graphene-based silver-based composite material with excellent comprehensive properties.

However, the redox method commonly used in the preparation process of graphene causes partial damage to the graphene structure, resulting in insufficient performance of its excellent properties, and the agglomeration of graphene in the matrix and the poor bonding between graphene and the matrix are also restricted. The application of graphene in silver matrix composites. Therefore, the development of a preparation method that can effectively control the graphene structure and realize the dispersion of graphene in the matrix and the tight bonding between the interface of graphene and the silver matrix is of great engineering significance for obtaining high-performance graphene-silver matrix composites. Practical value.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a silver-based composite material of nitrogen-doped graphene, which solves the problem of poor electrical conductivity of the existing graphene-silver-based composite material.

Another object of the present invention is to provide a method for preparing a nitrogen-doped graphene-based silver-based composite material.

The first technical solution adopted in the present invention is that a nitrogen-doped graphene-silver-based composite material is composed of the following components by mass percentage: Ag 99-99.9%, nitrogen-doped graphene 0.1-1%, and each of the above The sum of the mass percentages of the components is 100%, and the mass ratio of nitrogen elements in the nitrogen-doped graphene is 34.13-39.33%.

The second technical solution adopted in the present invention is a preparation method of a nitrogen-doped graphene silver-based composite material, and the specific operation steps are as follows:

Step 1, adding graphene oxide to deionized water, and ultrasonically dispersing to obtain graphene oxide dispersion;

Step 2, adding urea to the graphene oxide dispersion to obtain a mixed solution A, then performing ultrasonic dispersion treatment on the mixed solution A, and performing magnetic stirring while ultrasonically dispersing to obtain a mixed dispersion;

In step 3, the mixed dispersion is kept in a 160°C hydrothermal reactor for 4-7 hours, taken out, cooled to room temperature naturally, washed with absolute ethanol A, and then centrifuged, and the obtained precipitate is dried , that is, nitrogen-doped graphene powder;

Step 4, weigh 0.1-1% of the nitrogen-doped graphene powder, 99-99.9% of the Ag powder, and the sum of the mass percentages of the above components is 100% according to the mass percentage; disperse the nitrogen-doped graphene powder into anhydrous ethanol B , and ultrasonically treated for 30 min to obtain a nitrogen-doped graphene anhydrous ethanol solution; at the same time, the Ag powder was dispersed in another absolute ethanol C, and after ultrasonic treatment for 30 min, a silver-containing anhydrous ethanol solution was obtained, and then the nitrogen-doped graphene was The anhydrous ethanol solution and the silver-containing anhydrous ethanol solution are mixed and continue to be ultrasonically treated for 30 minutes, and then magnetically stirred at 60-80 ° C until the anhydrous ethanol is completely volatilized, that is, the composite powder is obtained;

Step 5, the composite powder is first subjected to ball milling treatment in a planetary ball mill, and then subjected to powder mixing treatment in a three-dimensional powder mixer to obtain mixed powder;

Step 6, pressing the mixed powder into a block and placing it in a sintering furnace in a nitrogen atmosphere, heating up to 500-800° C., holding the temperature for 2-3 hours, and pressing 20-50 MPa to finally obtain a nitrogen-doped graphene-silver-based composite material, which is nitrogen-doped. The silver-based composite material of graphene is composed of the following components by mass percentage: Ag99-99.9%, nitrogen-doped graphene 0.1-1%, the sum of the above components by mass percentage is 100%, and the nitrogen element in nitrogen-doped graphene is 100%. The mass ratio is 34.13-39.33%.

The present invention is also characterized in that,

It is characterized in that, the drying environment in step 3 is vacuum, the degree of vacuum is not less than 10 ^-2 Pa, the drying temperature is 60°C, and the drying time is 20-30h.

The mass ratio of graphene oxide to deionized water in step 1 is 1:0.5-1, the ultrasonic dispersion time of step 1 is 1-1.5h, and the mass ratio of graphene oxide dispersion to urea in step 2 is 1:30-40.

The time of the ball milling treatment in step 5 is 2-6h, and the time of the powder mixing treatment is 3-5h.

In step 4, the mass ratio of nitrogen-doped graphene powder to absolute ethanol B is 1:20, and the mass ratio of Ag powder to another absolute ethanol C is 1:20.

The beneficial effect of the present invention is that the silver-based composite material of nitrogen-doped graphene of the present invention improves the conductivity of the reduced graphene oxide by introducing nitrogen into the graphene, improves the dispersion of the graphene and improves the relationship between the graphene and the graphene. The wettability between metal matrices was obtained, and the N-doped graphene-silver-based bulk composite material with excellent comprehensive properties was obtained.

Description of drawings

Fig. 1 is the preparation flow chart of the silver-based composite material of a kind of nitrogen-doped graphene of the present invention;

2 is a scanning electron microscope photograph of a silver-based composite material of nitrogen-doped graphene of the present invention.

Detailed ways

The silver-based composite material of nitrogen-doped graphene provided by the present invention is composed of the following components by mass percentage: Ag 99-99.9%, nitrogen-doped graphene 0.1-1%, and the sum of the mass percentages of the above components is 100 %, the mass ratio of nitrogen element in nitrogen-doped graphene is 34.13-39.33%.

A specific process for the preparation of a nitrogen-doped graphene silver-based composite material is shown in Figure 1, and the specific operation steps are as follows:

Step 1, adding graphene oxide to deionized water, the mass ratio of graphene oxide to deionized water is 1:0.5-1, and ultrasonically dispersing for 1-1.5h to prepare graphene oxide dispersion;

Step 2, adding urea in the graphene oxide dispersion to obtain a mixed solution A, then carrying out ultrasonic dispersion treatment to the mixed solution A, carrying out magnetic stirring while ultrasonic dispersion, and the graphene oxide dispersion and urea mass ratio is 1 : 30-40 to obtain mixed dispersion;

Step 3, the mixed dispersion liquid is kept in a hydrothermal reactor at 160°C for 4-7 hours, then taken out, then cooled to room temperature naturally, washed with absolute ethanol, and then subjected to centrifugation, and the precipitate obtained after centrifugation is treated. Drying, the drying environment is vacuum, the vacuum degree is not less than 10 ^-2 Pa, the drying temperature is 60°C, and the drying time is 20-30h, that is, the nitrogen-doped graphene powder is obtained;

Step 4, weigh 0.1-1% of the nitrogen-doped graphene powder, 99-99.9% of the Ag powder, and the sum of the mass percentages of the above components is 100% according to the mass percentage; disperse the nitrogen-doped graphene powder into anhydrous ethanol B , the mass ratio of nitrogen-doped graphene powder to anhydrous ethanol B is 1:20, and after ultrasonic treatment for 30 min, nitrogen-doped graphene anhydrous ethanol solution is obtained; The mass ratio of powder to absolute ethanol C is 1:20, and after ultrasonic treatment for 30min, a silver-containing absolute ethanol solution is obtained; then the nitrogen-doped graphene absolute ethanol solution and the silver-containing absolute ethanol solution are mixed and continue Ultrasonic treatment was carried out for 30 min, followed by magnetic stirring at 60-80° C. until the absolute ethanol was completely volatilized to obtain a composite powder of nitrogen-doped graphene and silver powder.

In step 5, the composite powder is first ball-milled on a planetary ball mill for 2-6 hours, and then mixed in a three-dimensional powder mixer for 3-5 hours to obtain a mixed powder.

Step 6, pressing the mixed powder into a block and placing it in a sintering furnace in a nitrogen atmosphere, heating up to 500-800° C., holding the temperature for 2-3 hours, and pressing 20-50 MPa to finally obtain a silver-based composite material of nitrogen-doped graphene.

The present invention will be described in detail below with reference to specific embodiments.

Example 1

Step 1, adding graphene oxide to deionized water, the mass ratio of graphene oxide to deionized water is 1:0.5, and ultrasonically dispersing for 1 h to prepare graphene oxide dispersion;

Step 2, adding urea in the graphene oxide dispersion to obtain a mixed solution A, then carrying out ultrasonic dispersion treatment to the mixed solution A, carrying out magnetic stirring while ultrasonic dispersion, and the graphene oxide dispersion and urea mass ratio is 1 : 30 to obtain mixed dispersion;

Step 3, the mixed dispersion liquid is kept in a 160°C hydrothermal reactor for 4 hours, taken out, then cooled to room temperature naturally, washed with absolute ethanol, and then subjected to centrifugation, and the precipitate obtained after centrifugation is dried, The drying environment is vacuum, the vacuum degree is 1×10 ^-2 Pa, the drying temperature is 60°C, and the drying time is 20h, to obtain nitrogen-doped graphene powder;

Step 4, weigh 0.1% of nitrogen-doped graphene powder and 99.9% of Ag powder according to mass percentage; disperse the nitrogen-doped graphene powder into absolute ethanol B, and the mass ratio of nitrogen-doped graphene powder to absolute ethanol B is 1 : 20, and obtained nitrogen-doped graphene absolute ethanol solution after ultrasonic treatment for 30min; meanwhile, the Ag powder was dispersed in another absolute ethanol C, the mass ratio of Ag powder and absolute ethanol C was 1:20, and the ultrasonic After treatment for 30min, an anhydrous ethanol solution containing silver was obtained; then the nitrogen-doped graphene anhydrous ethanol solution and the silver-containing anhydrous ethanol solution were mixed, and the ultrasonic treatment was continued for 30min, followed by magnetic stirring at 60 ° C until the anhydrous ethanol was completely Volatilize, namely obtain composite powder.

Step 5, the composite powder is first ball-milled on a planetary ball mill for 2 hours, and then subjected to powder mixing treatment in a three-dimensional powder mixer for 3 hours to obtain a mixed powder;

In step 6, the mixed powder is pressed into a block and placed in a sintering furnace in a nitrogen atmosphere, heated to 500° C., kept for 2 hours, and a pressure of 20 MPa to finally obtain a nitrogen-doped graphene silver-based composite material.

Example 2

Step 1, adding graphene oxide to deionized water, the mass ratio of graphene oxide to deionized water is 1:1, and ultrasonically dispersing for 1.5h to prepare graphene oxide dispersion;

Step 2, adding urea in the graphene oxide dispersion to obtain a mixed solution A, then carrying out ultrasonic dispersion treatment to the mixed solution A, carrying out magnetic stirring while ultrasonic dispersion, and the graphene oxide dispersion and urea mass ratio is 1 : 40 to obtain mixed dispersion;

Step 3, the mixed dispersion liquid is kept in a 160° C. hydrothermal reactor for 7 hours, taken out, then cooled to room temperature naturally, washed with absolute ethanol, and then subjected to centrifugation, and the precipitate obtained after centrifugation is dried, The drying environment is vacuum, the vacuum degree is 0.5×10 ^-2 Pa, the drying temperature is 60°C, and the drying time is 30h, to obtain nitrogen-doped graphene powder;

Step 4, weigh 1% of nitrogen-doped graphene powder and 99% of Ag powder according to mass percentage; disperse the nitrogen-doped graphene powder into absolute ethanol B, and the mass ratio of nitrogen-doped graphene powder to absolute ethanol B is 1 : 20, and obtained nitrogen-doped graphene absolute ethanol solution after ultrasonic treatment for 30min; meanwhile, the Ag powder was dispersed in another absolute ethanol C, the mass ratio of Ag powder and absolute ethanol C was 1:20, and the ultrasonic After treatment for 30min, an anhydrous ethanol solution containing silver was obtained; then the nitrogen-doped graphene anhydrous ethanol solution and the silver-containing anhydrous ethanol solution were mixed, and the ultrasonic treatment was continued for 30min, followed by magnetic stirring at 80 °C until the anhydrous ethanol was completely Volatilize, namely obtain composite powder.

In step 5, the composite powder is first ball-milled on a planetary ball mill for 6 hours, and then mixed in a three-dimensional powder mixer for 5 hours to obtain a mixed powder.

In step 6, the mixed powder is pressed into a block and placed in a sintering furnace in a nitrogen atmosphere, heated to 800° C., maintained for 3 hours, and a pressure of 50 MPa to finally obtain a nitrogen-doped graphene silver-based composite material.

Example 3

Step 1, adding graphene oxide to deionized water, the mass ratio of graphene oxide to deionized water is 1:0.75, and ultrasonically dispersing for 1.25h to obtain graphene oxide dispersion;

Step 2, adding urea in the graphene oxide dispersion to obtain a mixed solution A, then carrying out ultrasonic dispersion treatment to the mixed solution A, carrying out magnetic stirring while ultrasonic dispersion, and the graphene oxide dispersion and urea mass ratio is 1 : 35, obtain mixed dispersion;

Step 3, the mixed dispersion liquid is kept in a hydrothermal reactor at 160°C for 4-7 hours, then taken out, then cooled to room temperature naturally, washed with absolute ethanol, and then subjected to centrifugation, and the precipitate obtained after centrifugation is treated. Drying, the drying environment is vacuum, the vacuum degree is 0.3×10 ^-2 Pa, the drying temperature is 60°C, and the drying time is 25h, that is, the nitrogen-doped graphene powder is obtained;

Step 4, weigh 0.5% of nitrogen-doped graphene powder and 99.5% of Ag powder according to mass percentage; disperse the nitrogen-doped graphene powder into absolute ethanol B, and the mass ratio of nitrogen-doped graphene powder to absolute ethanol B is 1 : 20, and obtained nitrogen-doped graphene absolute ethanol solution after ultrasonic treatment for 30min; meanwhile, the Ag powder was dispersed in another absolute ethanol C, the mass ratio of Ag powder and absolute ethanol C was 1:20, and the ultrasonic After treatment for 30min, an anhydrous ethanol solution containing silver was obtained; then the nitrogen-doped graphene anhydrous ethanol solution and the silver-containing anhydrous ethanol solution were mixed and continued to be ultrasonically treated for 30min, and then magnetically stirred at 70 ° C until the anhydrous ethanol was completely Volatilize, namely obtain composite powder.

In step 5, the composite powder is first ball-milled on a planetary ball mill for 4 hours, and then mixed in a three-dimensional powder mixer for 4 hours to obtain a mixed powder;

Step 6, pressing the mixed powder into a block and placing it in a sintering furnace in a nitrogen atmosphere, heating up to 650° C., holding the temperature for 2.5 hours, and pressing 35 MPa to finally obtain a nitrogen-doped graphene silver-based composite material.

Example 4

Step 1, adding graphene oxide to deionized water, the mass ratio of graphene oxide to deionized water is 1:0.5, and ultrasonically dispersing for 1.1 h to prepare graphene oxide dispersion;

Step 2, adding urea in the graphene oxide dispersion to obtain a mixed solution A, then carrying out ultrasonic dispersion treatment to the mixed solution A, carrying out magnetic stirring while ultrasonic dispersion, and the graphene oxide dispersion and urea mass ratio is 1 : 32, obtain mixed dispersion;

In step 3, the mixed dispersion is kept in a 160°C hydrothermal reactor for 6 hours, taken out, then cooled to room temperature naturally, washed with absolute ethanol, and then subjected to centrifugation, and the precipitate obtained by centrifugation is dried and dried. The environment is vacuum, the vacuum degree is 0.6×10 ^-2 Pa, the drying temperature is 60°C, and the drying time is 20h, that is, the nitrogen-doped graphene powder is obtained;

Step 4, weigh 0.1% of nitrogen-doped graphene powder and 99.9% of Ag powder according to mass percentage; disperse the nitrogen-doped graphene powder into absolute ethanol B, and the mass ratio of nitrogen-doped graphene powder to absolute ethanol B is 1 : 20, and obtained nitrogen-doped graphene absolute ethanol solution after ultrasonic treatment for 30min; meanwhile, the Ag powder was dispersed in another absolute ethanol C, the mass ratio of Ag powder and absolute ethanol C was 1:20, and the ultrasonic After treatment for 30min, an anhydrous ethanol solution containing silver was obtained; then the nitrogen-doped graphene anhydrous ethanol solution and the silver-containing anhydrous ethanol solution were mixed, and the ultrasonic treatment was continued for 30min, followed by magnetic stirring at 80 °C until the anhydrous ethanol was completely Volatilize, namely obtain composite powder.

Step 5, the composite powder is first ball-milled on a planetary ball mill for 3 hours, and then subjected to powder mixing treatment in a three-dimensional powder mixer for 4 hours to obtain a mixed powder;

Step 6, pressing the mixed powder into a block and placing it in a sintering furnace in a nitrogen atmosphere, heating up to 550° C., holding the temperature for 3 hours, and pressing 30 MPa to finally obtain a nitrogen-doped graphene silver-based composite material.

Example 5

Step 1, adding graphene oxide to deionized water, the mass ratio of graphene oxide to deionized water is 1:0.7, and ultrasonically dispersing for 1.5h to prepare graphene oxide dispersion;

Step 2, adding urea in the graphene oxide dispersion to obtain a mixed solution A, then carrying out ultrasonic dispersion treatment to the mixed solution A, carrying out magnetic stirring while ultrasonic dispersion, and the graphene oxide dispersion and urea mass ratio is 1 : 35 to obtain a mixed dispersion;

Step 3, the mixed dispersion liquid is kept in a 160° C. hydrothermal reactor for 7 hours, taken out, then cooled to room temperature naturally, washed with absolute ethanol, and then subjected to centrifugation, and the precipitate obtained after centrifugation is dried, The drying environment is vacuum, the vacuum degree is 1×10 ^-2 Pa, the drying temperature is 60°C, and the drying time is 25h, to obtain nitrogen-doped graphene powder;

Step 4, weigh 0.3% of nitrogen-doped graphene powder and 99.7% of Ag powder according to mass percentage; disperse the nitrogen-doped graphene powder into absolute ethanol B, and the mass ratio of nitrogen-doped graphene powder to absolute ethanol B is 1 : 20, and obtained nitrogen-doped graphene absolute ethanol solution after ultrasonic treatment for 30min; meanwhile, the Ag powder was dispersed in another absolute ethanol C, the mass ratio of Ag powder and absolute ethanol C was 1:20, and the ultrasonic After treatment for 30min, an anhydrous ethanol solution containing silver was obtained; then the nitrogen-doped graphene anhydrous ethanol solution and the silver-containing anhydrous ethanol solution were mixed and continued to be ultrasonically treated for 30min, and then magnetically stirred at 70 ° C until the anhydrous ethanol was completely Volatilize, namely obtain composite powder.

In step 5, the composite powder is first subjected to ball milling treatment in a planetary ball mill, and the ball milling time is 5 h, and then the powder mixing treatment is carried out in a three-dimensional powder mixer, and the powder mixing time is 3.5 h to obtain mixed powder;

Step 6, pressing the mixed powder into a block and placing it in a sintering furnace in a nitrogen atmosphere, heating up to 700° C., holding the temperature for 2.5 hours, and pressing 40 MPa to finally obtain a nitrogen-doped graphene silver-based composite material.

Fig. 2 is a scanning electron microscope photo of nitrogen-doped graphene, which shows the nitrogen-doped graphene with a thinner sheet-like and wrinkled structure.

The performance parameters of examples and traditional silver matrix composites are shown in Table 1

Comparison of performance parameters between the embodiment of table 1 and the traditional silver matrix composite material

sample name Conductivity/IACS Hardness/HV Example 4 97.41% 92.3 Example 5 93.97% 85.13 Silver Matrix Composites of Traditional SnO₂ 67.58% 81.71

It can be clearly seen from Example 4 and Example 5 that the silver-based composite material of nitrogen-doped graphene prepared by the present invention has excellent electrical conductivity and hardness. Compared with the traditional _SnO2 -based silver-based composites, the conductivity and hardness of the silver-based composites prepared in Example 4 were increased by 44.14% and 12.96%, respectively. The conductivity and hardness of the silver-based composite material prepared in Example 5 were increased by 39.05% and 4.18%, respectively. The silver-based composite material prepared by the invention can be widely used in electrical fields such as relays, contactors, and low-voltage switches.

Claims (5)

1. a preparation method of the silver-based composite material of nitrogen-doped graphene, is characterized in that, concrete operation steps are as follows: Step 1, adding graphene oxide to deionized water, and ultrasonically dispersing to obtain graphene oxide dispersion; Step 2, adding urea to the graphene oxide dispersion to obtain a mixed solution A, then carrying out ultrasonic dispersion treatment on the mixed solution A, and performing magnetic stirring while ultrasonically dispersing to obtain a mixed dispersion; Step 3, the mixed dispersion is taken out after being kept in a 160 ℃ hydrothermal reactor for 4-7 hours, then cooled to room temperature naturally, then washed with absolute ethanol A, and then centrifuged to obtain The precipitate is dried to obtain nitrogen-doped graphene powder; Step 4, weigh 0.1-0.3% of the nitrogen-doped graphene powder and 99-99.9% of the Ag powder according to the mass percentage, and the sum of the mass percentages of the above components is 100%, and then disperse the nitrogen-doped graphene powder to no In water ethanol B, and ultrasonically treated for 30min to obtain a nitrogen-doped graphene absolute ethanol solution, at the same time, the Ag powder was dispersed in another absolute ethanol C, and after ultrasonic treatment for 30min, a silver-containing absolute ethanol solution was obtained , and then mix the nitrogen-doped graphene anhydrous ethanol solution and the silver-containing anhydrous ethanol solution and continue ultrasonic treatment for 30min, and then magnetically stir at 60-80 ° C until the anhydrous ethanol is completely volatilized to obtain a composite powder. ; Step 5, the composite powder is first subjected to ball milling treatment in a planetary ball mill, and then subjected to powder mixing treatment in a three-dimensional powder mixer to obtain mixed powder; Step 6, pressing the mixed powder into a block and placing it in a sintering furnace in a nitrogen atmosphere, heating up to 500-800° C., holding the temperature for 2-3h, and pressing 20-50MPa, and finally obtaining a silver-based composite material of nitrogen-doped graphene, The nitrogen-doped graphene-silver-based composite material is composed of the following components by mass percentage: Ag99.7-99.9%, nitrogen-doped graphene 0.1-0.3%, and the sum of the mass percentages of the above components is 100%. The mass proportion of nitrogen element in nitrogen-doped graphene is 34.13-39.33%. 2. the preparation method of the silver-based composite material of a kind of nitrogen-doped graphene according to claim 1, is characterized in that, the drying environment described in step 3 is vacuum, vacuum degree is not less than ^10-2 Pa, drying temperature 60 ℃ ℃, drying time 20-30h. 3. the preparation method of the silver-based composite material of a kind of nitrogen-doped graphene according to claim 1, is characterized in that, the graphene oxide described in step 1 and deionized water mass ratio are 1:0.5-1, The ultrasonic dispersion time described in step 1 is 1-1.5h; the mass ratio of graphene oxide dispersion liquid and urea described in step 2 is 1:30-40. 4. the preparation method of the silver-based composite material of a kind of nitrogen-doped graphene according to claim 1, is characterized in that, the time of the ball milling process described in step 5 is 2-6h, and the time of three-dimensional powder mixing process is 3 -5h. 5. the preparation method of the silver-based composite material of a kind of nitrogen-doped graphene according to claim 1, is characterized in that, the mass ratio of nitrogen-doped graphene powder described in step 4 and dehydrated alcohol B is 1:20, The mass ratio of the Ag powder to the additional absolute ethanol C was 1:20.

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