Preparation method and application of bismuth sulfide-reduced graphene oxide composite material

Abstract

The application relates to the technical field of electromagnetic wave absorbing materials, and provides a preparation method and application of a bismuth sulfide-reduced graphene oxide composite material. The main purpose is to solve the problems of high cost, environmental pollution and insufficient absorption capacity of single material of traditional metal material absorbers. The main scheme comprises the following steps: synthesizing graphene oxide nanosheets, taking ethylene glycol as a solvent medium, taking polyvinylpyrrolidone K30 as a surfactant, adding bismuth nitrate pentahydrate and thiourea, and in-situ preparing the bismuth sulfide-reduced graphene oxide composite material through a solvothermal reaction. The application is used for electromagnetic functional materials, including microwave absorbing materials and electromagnetic shielding materials. The composite material is used as a filler and mixed with paraffin or epoxy resin to be coated on the surface of a protected object, so that electromagnetic wave absorption and shielding are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic wave absorbing materials, and provides a preparation method and application of a bismuth sulfide-reduced graphene oxide composite material. BACKGROUND

[0002] In recent years, the wide application of electromagnetic waves has brought serious problems such as mutual interference between electronic devices and harm to human health, so the development of materials that can effectively absorb electromagnetic waves has become a key issue that needs to be solved urgently. Although traditional metal materials have excellent performance, they have high cost and serious environmental pollution problems, which restrict their further application. In addition, the electromagnetic wave interference scene is complex, and the single material absorption capacity is not enough to meet the demand, so it is urgent to develop new composite material absorbers.

[0003] Metal sulfide semiconductor materials have broad application prospects in the fields of catalysis, energy, and optoelectronic devices due to their unique structure and performance, and have gradually become the focus of attention in the field of electromagnetic wave absorbers. Among them, bismuth sulfide is considered to have potential wave absorption application value due to its excellent semiconductor performance and strong one-dimensional growth tendency.

[0004] However, the low conductivity of bismuth sulfide limits its application, and it is usually necessary to be compounded with other materials to improve its dielectric loss performance and achieve better wave absorption effect. Carbon materials are usually used for compounding. Researchers use various strategies to prepare such absorbers, such as introducing matching units, introducing magnetic units, enhancing polarization relaxation, and super-composite material design. The research group of Huang Xiaoxiao of Harbin Institute of Technology prepared a micron flower-like 1T / 2H phase molybdenum disulfide wave-absorbing material. It was found that when the matching thickness was 2.68 mm, the lowest reflection loss reached nearly-59.8 dB, and when the matching thickness was 2.48 mm, the effective absorption bandwidth was 6.8 GHz. (Xiaoxiao Huang, Yuefeng Yan, Kailei Zhang, Guangyu Qin, Yu Zhou, Preparation method of a micron flower-like 1T / 2H phase molybdenum disulfide wave-absorbing material CN117963987A, 2024-05-03.) Jiang et al. prepared boron nitride / reduced graphene oxide (BN / RGO) nanocomposites by one-step thermal nitridation process. The wave-absorbing performance of the obtained BN / RGO hybrid material is 4.2 GHz in the effective absorption bandwidth and reaches a maximum reflection loss (RL) of-48.9 dB at a thickness of 2.6 mm. (Zhiyang Jiang, Haoxu Si, Xin Chen, Huimin Liu, Lei Zhang, Yahong Zhang, Chunhong Gong, and Jingwei Zhang, Composites Communications 22, 100503 (2020).) In summary, bismuth sulfide materials have good potential for electromagnetic wave absorption performance, but there are usually several outstanding problems: one, the conductivity of pure bismuth sulfide is poor, and the impedance is easy to mismatch, which makes its wave-absorbing performance poor; two, the stability of single rod structure is low, and the wave-absorbing environment is complex, which requires a more stable architecture; three, the process is complex, and the cost is high, which is not conducive to large-scale production. SUMMARY

[0005] The purpose of the present application is to provide a bismuth sulfide-reduced graphene oxide composite material with easy preparation, adjustable electrical conductivity, stable properties, and strong broadband microwave absorption performance, as well as a preparation method thereof. Another purpose is to provide the application of the bismuth sulfide-reduced graphene oxide composite material in electromagnetic wave absorption.

[0006] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0007] The present application provides a bismuth sulfide-reduced graphene oxide composite material, wherein the surface of the reduced graphene oxide nanosheet has rod-shaped Bi2S3, and the rod-shaped Bi2S3 is grown in situ during the solvothermal process of the graphene oxide nanosheet.

[0008] The application further provides a preparation method of the bismuth sulfide-reduced graphene oxide composite material.

[0009] Synthesizing graphene oxide nanosheets, ready for use;

[0010] In the solvent medium of ethylene glycol, using polyvinylpyrrolidone K30 as the surfactant, graphene oxide nanosheet as the base, adding bismuth nitrate pentahydrate and thiourea, mixing and stirring uniformly, then transferring to the inner liner of the hydrothermal kettle, heating to the reaction temperature, and the reaction temperature is between 180-220℃;

[0011] The solvothermal reaction time is 8-18 hours, after the reaction is completed, the hydrothermal kettle is completely cooled to room temperature, and the black powder formed on the inner wall of the inner liner is the bismuth sulfide-reduced graphene oxide composite material.

[0012] In the above scheme, the polytetrafluoroethylene inner liner of the hydrothermal kettle is cleaned:

[0013] The inner wall of the polytetrafluoroethylene inner liner of the hydrothermal kettle and the inner wall of the cover are washed with flowing tap water, then 800-1200 mL of deionized water is used to wash the inner wall of the inner liner and the inner wall of the cover, then 50-100 mL of anhydrous ethanol is used to fill the inner liner, and the inner liner is placed in an ultrasonic cleaner for ultrasonic cleaning for 15-25 min;

[0014] In the above scheme, the synthesis of graphene oxide powder:

[0015] Step a1. A dry container is placed in a water bath, a mechanical stirring device is fixed above the bottle mouth, 3g of graphite flakes, 360mL of sulfuric acid, 40mL of orthophosphoric acid and 18g of potassium permanganate are sequentially added, and stirring is performed in the water bath at 46℃ for 12-16h;

[0016] Step a2. A beaker containing 350-450mL of deionized water is placed in an ice bath, the solution after stirring in a1 is slowly added, 10-15mL of hydrogen peroxide is added dropwise after cooling, until the solution turns bright yellow;

[0017] Step a3. Then the bright yellow solution described in ② is washed with deionized water, and the washing is performed for 3-5 times, centrifuged until the pH value of the solution is close to 7.0, the finally washed product is freeze-dried to obtain dry graphene oxide powder, and the graphene oxide powder is stored for standby use;

[0018] In the above scheme, the synthesis of the bismuth sulfide-reduced graphene oxide composite material:

[0019] Step b1. Dissolve 20-80 mg of graphene oxide powder prepared in step a3 in 30-50 mL of ethylene glycol, ultrasonic for 15-25 min, then add 0.05-0.2 g of polyvinylpyrrolidone K30 powder, stir for 20-40 min;

[0020] Step b2. Add 0.8-1.5 g of bismuth nitrate pentahydrate and 0.1-0.6 g of thiourea, then stir the mixed solution for 20-40 min;

[0021] Step b3. Transfer to a 100 mL stainless steel autoclave with a polytetrafluoroethylene liner, seal and keep at 180-220℃ for 8-18 hours;

[0022] Step b4. After the whole hydrothermal kettle is completely cooled to room temperature, open the polytetrafluoroethylene liner and collect the black powder in the centrifuge tube, which is the bismuth sulfide-reduced graphene oxide composite material;

[0023] Step b5. Wash the black powder in step b4 with deionized water and anhydrous ethanol, dry the black powder at 60-80℃, and store after complete drying.

[0024] The application also provides an application of the bismuth sulfide-reduced graphene oxide composite material, which is used as an electromagnetic functional material, including but not limited to microwave absorbing materials and electromagnetic shielding materials.

[0025] In the above scheme, the method of using the bismuth sulfide-reduced graphene oxide composite material is to uniformly mix the bismuth sulfide-reduced graphene oxide composite material as a filler with paraffin or epoxy resin in proportion, coat the surface of the protected object, and use it as a coating.

[0026] Because the application adopts the above technical means, the following beneficial effects are achieved:

[0027] (1) The bismuth sulfide-reduced graphene oxide composite material has good electromagnetic wave absorption performance and can be used as an electromagnetic functional material, including but not limited to microwave absorbing materials and electromagnetic shielding materials.

[0028] (2) The bismuth sulfide-reduced graphene oxide composite material is prepared in situ under solvothermal conditions with graphene oxide nanosheets as the substrate, bismuth nitrate pentahydrate as the bismuth source, and thiourea as the sulfur source, and has the characteristics of simple reaction process flow, high yield, and tunable product conductivity.

[0029] (3) The morphology, properties and yield of bismuth sulfide-reduced graphene oxide composite material can be adjusted by controlling the concentration of graphene oxide, the concentration of sulfur source and bismuth source, the temperature of solvothermal reaction and the reaction time. Therefore, the present invention has the characteristics of simple process, easy operation and large-scale production. Attached Figure Description

[0030] Figure 1 This is a SEM image of the bismuth sulfide-reduced graphene oxide composite material prepared in Example 1 of the present invention;

[0031] Figure 2 This is a TEM image of the bismuth sulfide-reduced graphene oxide composite material prepared in Example 1 of the present invention;

[0032] Figure 3 The XRD pattern of the bismuth sulfide-reduced graphene oxide composite material prepared in Example 1 of this invention;

[0033] Figure 4 The image shows the reflection loss spectrum of the bismuth sulfide-reduced graphene oxide composite material prepared in Example 1 of this invention. Detailed Implementation

[0034] The embodiments of the present invention will be described in detail below. Although the present invention will be described and illustrated in conjunction with some specific embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, any modifications or equivalent substitutions made to the present invention should be covered within the scope of the claims of the present invention.

[0035] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without these specific details.

[0036] This invention provides a bismuth sulfide-reduced graphene oxide composite material, wherein the surface of the reduced graphene oxide nanosheets has rod-shaped Bi2S3, which is grown in situ during the solvothermal process of the graphene oxide nanosheets.

[0037] This invention also provides a method for preparing a bismuth sulfide-reduced graphene oxide composite material, comprising the following steps:

[0038] Synthesize graphene oxide nanosheets for later use;

[0039] Using ethylene glycol as the solvent medium, polyvinylpyrrolidone K30 as the surfactant, and graphene oxide nanosheets as the substrate, bismuth nitrate pentahydrate and thiourea were added, mixed and stirred evenly, and then transferred to the lining of a hydrothermal reactor. The mixture was heated to the reaction temperature, which was between 180 and 220°C.

[0040] The solvent thermal reaction time is 8-18 hours, the hydrothermal kettle is completely cooled to room temperature after the reaction is over, and the black powder formed on the inner wall of the inner lining is the bismuth sulfide-reduced graphene oxide composite material.

[0041] In the above scheme, the polytetrafluoroethylene lining of the hydrothermal kettle is cleaned:

[0042] The inner wall of the polytetrafluoroethylene lining of the hydrothermal kettle and the inner wall of the cover are washed with flowing tap water, and then 800-1200 mL of deionized water is used to wash the inner wall of the lining and the inner wall of the cover, and then 50-100 mL of anhydrous ethanol is used to fill the lining, which is placed in an ultrasonic cleaner for 15-25 min.

[0043] In the above scheme, the chemical reaction raw materials are prepared:

[0044] The chemical raw materials required for preparing the bismuth sulfide-reduced graphene oxide composite material are prepared, all chemical reagents are analytical grade reagents, and do not need to be further purified and can be directly used, as follows:

[0045] Flaky graphite: solid, purity ≥ 99.5%;

[0046] Potassium permanganate: solid, purity ≥ 99.5%;

[0047] Bismuth nitrate pentahydrate: solid, purity ≥ 99.0%;

[0048] Thiourea: solid, purity ≥ 99.0%;

[0049] Polyvinylpyrrolidone K30: solid, purity ≥ 99.0%;

[0050] Sulfuric acid: liquid, concentration ≥ 98%;

[0051] Orthophosphoric acid: liquid, purity ≥ 98%;

[0052] Hydrogen peroxide: liquid, concentration ≥ 30%;

[0053] Ethanol: liquid, purity ≥ 99.7%;

[0054] Ethylene glycol: liquid, purity ≥ 99.5%;

[0055] Deionized water: liquid, purity ≥ 99.99%.

[0056] In the above scheme, the synthesis of graphene oxide powder:

[0057] Step a1. Place a dry container in a water bath, fix a mechanical stirring device above the bottle mouth, and sequentially add 3 g of flaky graphite, 360 mL of sulfuric acid, 40 mL of orthophosphoric acid, and 18 g of potassium permanganate, and stir in a 46°C water bath for 12-16 h;

[0058] Step a2. A beaker containing 350-450 mL of deionized water was placed in an ice bath, and the stirred solution in a1 was slowly added. After cooling, 10-15 mL of hydrogen peroxide was added dropwise until the solution turned bright yellow;

[0059] Step a3. The bright yellow solution in ② was then washed with deionized water, 3-5 times, and centrifuged until the pH of the solution was close to 7.0. The final washed product was freeze-dried to obtain a dry graphene oxide powder, which was stored for later use;

[0060] In the above scheme, the synthesis of bismuth sulfide-reduced graphene oxide composite material:

[0061] Step b1. 20-80 mg of graphene oxide powder prepared in step a3 was dissolved in 30-50 mL of ethylene glycol, and ultrasonicated for 15-25 min. Then, 0.05-0.2 g of polyvinylpyrrolidone K30 powder was added, and stirred for 20-40 min;

[0062] Step b2. 0.8-1.5 g of bismuth nitrate pentahydrate and 0.1-0.6 g of thiourea were added, and the mixed solution was stirred for 20-40 min;

[0063] Step b3. It was transferred to a 100 mL stainless steel autoclave with a polytetrafluoroethylene liner, sealed and kept at 180-220 °C for 8-18 hours;

[0064] Step b4. After the hydrothermal kettle was completely cooled to room temperature, the polytetrafluoroethylene liner was opened, and the black powder in the centrifuge tube was collected. This black powder was the bismuth sulfide-reduced graphene oxide composite material;

[0065] Step b5. The black powder in step b4 was washed with deionized water and anhydrous ethanol several times, and dried at 60-80 °C. After complete drying, it was stored for later use.

[0066] The prepared black solid powder, i.e., the bismuth sulfide-reduced graphene oxide composite material, was analyzed for morphology, chemical composition, performance, and other characterization. The morphology of the composite material was analyzed by field emission scanning electron microscopy. The microstructure of the composite material was analyzed by high-resolution transmission electron microscopy. The composition of the product was analyzed by X-ray powder diffraction. The electromagnetic parameters of the composite material were tested by a vector network analyzer.

[0067] Conclusion: The product is black, bismuth sulfide-reduced graphene oxide composite material; the rod-shaped structure has a diameter of 50 nanometers and a length of several microns; the sheet-shaped structure has an area of several tens of square microns; the product contains elements such as sulfur, bismuth and carbon; the maximum reflection attenuation in the Ku band can reach 24.1 dB, and the effective absorption bandwidth can reach 6.72 GHz, that is, it has good electromagnetic wave absorption performance.

[0068] The application also provides an application of the bismuth sulfide-reduced graphene oxide composite material, which is used as an electromagnetic functional material, including but not limited to a microwave absorbing material and an electromagnetic shielding material.

[0069] In the above scheme, the method using the bismuth sulfide-reduced graphene oxide composite material is as follows: the bismuth sulfide-reduced graphene oxide composite material is used as a filler, uniformly mixed with paraffin or epoxy resin in proportion, coated on the surface of a protected object, and used as a coating.

[0070] Example 1:

[0071] The preparation method of the bismuth sulfide-reduced graphene oxide composite material of the application comprises the following steps:

[0072] (1) Synthesis of graphene oxide nanosheets.

[0073] A dry three-necked flask is placed in a water bath, a mechanical stirring device is fixed above the mouth of the flask, 3g of graphite flakes, 360mL of sulfuric acid, 40mL of orthophosphoric acid and 18g of potassium permanganate are sequentially added, and stirring is performed in a 46℃ water bath for 12h:

[0074] A beaker containing 400mL of deionized water is placed in an ice bath, the solution stirred for 12h is slowly added, 10mL of hydrogen peroxide is added dropwise after cooling, until the solution turns bright yellow. Then, the aforementioned bright yellow solution is washed with deionized water for 3 times, centrifuged until the pH value of the solution approaches 7.0, and the finally washed product is freeze-dried to obtain dry graphene oxide powder, which is stored for use;

[0075] (2) Synthesis of bismuth sulfide-reduced graphene oxide composite material

[0076] 20mg of graphene oxide powder is dissolved in 40mL of ethylene glycol, ultrasonically treated for 15min, then 0.1g of polyvinylpyrrolidone K30 powder is added, and stirred for 20min. Then, 1g of bismuth nitrate pentahydrate and 0.2g of thiourea are added, and the mixed solution is stirred for 20min. Then, the solution is transferred to a 100mL polytetrafluoroethylene-lined stainless steel autoclave, sealed and kept at 180℃ for 10h.

[0077] After the hydrothermal kettle is completely cooled to room temperature, the polytetrafluoroethylene lining is carefully opened, and the black powder in the centrifuge tube is collected, which is the bismuth sulfide-reduced graphene oxide composite material.

Claims

1. A method for preparing a bismuth sulfide-reduced graphene oxide composite material, characterized by, Comprising the following steps: Step 1: Synthesis of graphene oxide nanosheets, ready for use; Step 2: Dissolve 20-80 mg of the graphene oxide powder in 30-50 mL of ethylene glycol, ultrasonic for 15-25 min, add 0.05-0.2 g of polyvinylpyrrolidone K30, stir for 20-40 min; Step 3: Add 0.8-1.5 g of bismuth nitrate pentahydrate and 0.1-0.6 g of thiourea to the solution obtained in step 2, continue to stir for 20-40 min, to obtain a mixed solution; Step 4: Transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, seal and react at 180-220℃ for 8-18 hours; Step 5: After the reactor is naturally cooled to room temperature, collect the black powder in the liner, and the bismuth sulfide-reduced graphene oxide composite material is obtained; wherein the rod-shaped Bi2S3 is in-situ grown on the surface of the reduced graphene oxide nanosheet in the composite material.

2. The preparation method of the bismuth sulfide-reduced graphene oxide composite material as described in claim 1, characterized in that, Washing the polytetrafluoroethylene liner of the hydrothermal kettle: Rinse the inner wall of the polytetrafluoroethylene liner of the hydrothermal kettle and the inner wall of the cover with flowing tap water, then rinse the inner wall of the liner and the inner wall of the cover with 800-1200 mL of deionized water, then fill the liner with 50-100 mL of anhydrous ethanol, and place it in an ultrasonic cleaner for 15-25 min.

3. The preparation method of the bismuth sulfide-reduced graphene oxide composite material as described in claim 2, characterized in that, Synthesis of graphene oxide powder: Step a1. Place a dry container in a water bath, fix a mechanical stirring device above the bottle mouth, and sequentially add 3 g of phosphorus flake graphite, 360 mL of sulfuric acid, 40 mL of orthophosphoric acid, and 18 g of potassium permanganate, and stir in a 46℃ water bath for 12-16 h; Step a2. Place a beaker containing 350-450 mL of deionized water in an ice bath, slowly add the stirred solution in a1, and after cooling, add 10-15 mL of hydrogen peroxide dropwise until the solution turns bright yellow; Step a3. Then wash the bright yellow solution in step a2 with deionized water, 3-5 times, centrifuge until the pH of the solution is close to 7.0, and freeze-dry the final washed product to obtain dry graphene oxide powder, and store for later use.

4. Use of a composite material prepared according to the method of claim 1, characterized in that, The bismuth sulfide-reduced graphene oxide composite material is used as an electromagnetic functional material, including but not limited to microwave absorbing materials and electromagnetic shielding materials.

5. Use of a composite material prepared according to the method of claim 4, characterized in that, The method of using the bismuth sulfide-reduced graphene oxide composite material is to uniformly mix the bismuth sulfide-reduced graphene oxide composite material as a filler with paraffin or epoxy resin in proportion, and coat the surface of the protected object as a coating.

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