A kind of waste soybean shell derived porous carbon @VS2 composite material and its preparation method and application

Abstract

The present invention provides a waste green soybean shell-derived porous carbon@VS2 composite material, its preparation method and application. First, the green soybean shells are pretreated, and then the pretreated green soybean shells are heat-treated in an inert gas to carbonize them. Finally, the heat-treated and carbonized green soybean shells are placed in a mixed solution of thioacetamide, ammonium metavanadate, ammonia water and deionized water for hydrothermal treatment, and VS2 is in-situ grown on the surface of the green soybean shell-derived porous carbon, and the composite material is obtained by washing and drying. The composite material has the characteristics of strong electromagnetic wave absorption, wide effective absorption frequency band, thin thickness, etc., and has great potential for electromagnetic wave absorption applications. In addition, the preparation method of the composite material has the characteristics of stable control, simplicity and easy operation.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic absorption materials in the field of functional materials, and specifically relates to a porous carbon@VS2 composite material derived from discarded edamame shells, and a preparation method and application thereof. Background Art

[0002] With the rapid development of modern science and technology and electronic communications, various electronic and electrical equipment have provided high efficiency for social production and brought great convenience to people's daily life. At the same time, the electromagnetic radiation and interference generated during the operation of electronic and electrical equipment will greatly affect our production and life. On the one hand, it will cause serious interference to other surrounding electronic equipment, instruments, communication signals, etc., and even fail to work normally and cause serious consequences; on the other hand, electromagnetic pollution will also cause great damage to humans and the natural environment. In addition to preventing a series of serious consequences brought about by electromagnetic wave pollution, countries are also working hard to improve their national defense and increase research on new weapons. Therefore, whether in the civilian or military fields, materials with efficient electromagnetic wave absorption or shielding properties are widely needed, and the preparation of new absorbing materials has also become a current research hotspot.

[0003] Carbon materials such as carbon nanotubes, carbon fibers, and graphene have the advantages of low density, light weight, stable physical and chemical properties, and wide absorption bandwidth, and are widely used in the field of electromagnetic wave absorption. However, their relatively complex preparation process limits the application of carbon materials in the field of electromagnetic wave absorption. Biomass carbon materials are new materials inspired by biological structures. They have different internal structures, and their structural diversity provides a very broad space for scientific research and application. After carbonization, the original interesting structure of biomass can be well preserved and provides a carbon source. However, the relatively high complex dielectric constant of pure carbon materials leads to impedance mismatch, which is not conducive to achieving high electromagnetic wave absorption performance. Summary of the invention

[0004] An effective way is to combine carbon materials with other dielectric materials and improve impedance matching and attenuation capabilities through reasonable structural design. Edamame shells are common kitchen waste in daily life. They have a porous structure and can provide an ideal template for the preparation of porous carbon materials. By controlling the appropriate carbonization temperature, a matrix with certain wave-absorbing properties can be obtained. However, the impedance matching characteristics of pure carbon materials are poor and need to be further improved. Vanadium disulfide (VS2) is a VB group metal sulfide that can respond well to changes in electromagnetic fields and dissipate electromagnetic energy. VS2 is synthesized in situ on the surface and cross-section of porous carbon using a hydrothermal method, which not only improves the impedance matching of the composite material, but also improves the attenuation capability.

[0005] In order to solve the above problems, the present invention uses soybean shell as a biomass template, and utilizes carbonization and hydrothermal methods to in-situ synthesize VS2 on the surface and cross section of soybean shell derived porous carbon. Provided is a waste soybean shell derived porous carbon@VS2 composite material and its preparation method and application.

[0006] The specific technical solutions of the present invention are as follows:

[0007] The present invention provides a method for preparing a porous carbon @VS2 composite material derived from waste edamame shells, which is characterized in that it comprises the following steps: step S1, pretreating edamame shells to obtain pretreated edamame shells; step S2, heat-treating the pretreated edamame shells in an inert gas to obtain heat-treated edamame shells; step S3, dissolving thioacetamide, ammonium metavanadate and ammonia water in deionized water to obtain a mixed solution; step S4, adding the heat-treated edamame shells to the mixed solution, performing hydrothermal treatment, washing and drying to obtain the porous carbon @VS2 composite material derived from waste edamame shells, wherein the mass ratio of the heat-treated edamame shells, thioacetamide, ammonium metavanadate, ammonia water and deionized water is 1:(7-9):(2-3):(30-35):(165-170).

[0008] The method for preparing the waste edamame shell-derived porous carbon@VS2 composite material provided by the present invention also has the following technical features, wherein the pretreatment process in step S1 is: washing the edamame shell with deionized water and anhydrous ethanol, and drying.

[0009] The preparation method of the waste edamame shell-derived porous carbon@VS2 composite material provided by the present invention also has the following technical characteristics, wherein the inert gas in step S2 is argon, the heat treatment temperature is 650-750°C, the time is 100-150min, and the heating rate is 3-8°C / min.

[0010] The preparation method of the waste edamame shell-derived porous carbon@VS2 composite material provided by the present invention also has the following technical characteristics, wherein the temperature of the hydrothermal treatment in step S4 is 150-200°C, the time is 18-24h, the heating rate is 3-8°C / min, the washing detergent is deionized water and anhydrous ethanol, and the drying temperature is 50-80°C.

[0011] The present invention also provides a waste edamame husk-derived porous carbon @VS2 composite material, which is characterized in that it is prepared by using the above-mentioned preparation method of the waste edamame husk-derived porous carbon @VS2 composite material.

[0012] The present invention also provides an application of the above-mentioned waste edamame shell-derived porous carbon@VS2 composite material in electromagnetic wave absorption.

[0013] Functions and Effects of the Invention

[0014] The preparation method of the waste edamame shell-derived porous carbon @VS2 composite material provided by the present invention is to first pretreat the edamame shells, then heat-treat the pretreated edamame shells in an inert gas to carbonize them, and finally put the heat-treated carbonized edamame shells into a mixed solution of thioacetamide, ammonium metavanadate, ammonia water and deionized water for hydrothermal treatment, washing and drying to obtain the composite material.

[0015] The present invention uses waste soybean shells as raw materials, obtains soybean shell-derived porous carbon by carbonization, and then uses a hydrothermal method to in-situ grow VS2 on the surface of the soybean shell-derived porous carbon to obtain a waste soybean shell-derived porous carbon@VS2 composite material. Therefore, compared with the prior art, the composite material has the characteristics of strong electromagnetic wave absorption, wide effective absorption bandwidth, and thin thickness, and can meet the current requirements for electromagnetic wave absorbing materials. In addition, the preparation method of the composite material is stable, controllable, simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the XRD spectrum of SHVS prepared in the embodiment of the present invention, PVS prepared in Comparative Example 1 and PSH prepared in Comparative Example 2.

[0017] Figure 2 SHVS prepared in the embodiment of the present invention, PVS prepared in Comparative Example 1, and PSH prepared in Comparative Example 2 are SEM and EDS images, wherein: Figure 2 (a) and (e) are SEM images of PVS prepared in Comparative Example 1; Figure 2 (b) and (f) are SEM images of PSH prepared in Comparative Example 2; Figure 2 (c), (d), (g) and (h) are SEM images of SHVS prepared in the embodiments of the present invention; Figure 2 (i) is the EDS graph of the SHVS prepared in the embodiment of the present invention.

[0018] Figure 3 SHVS prepared in the embodiment of the present invention, PVS prepared in Comparative Example 1, and PSH prepared in Comparative Example 2 are shown in the figure. Figure 3 a in the figure is a graph showing the wave absorption performance of PVS obtained in Comparative Example 1; Figure 3 b is a graph showing the wave absorption performance of the PSH obtained in Comparative Example 2; Figure 3 c in FIG. 1 is a diagram showing the wave absorption performance of the SHVS prepared in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The terms used in the present invention, unless otherwise specified, generally have the meanings that are commonly understood by those of ordinary skill in the art.

[0020] In the following examples, various processes and methods not described in detail are conventional methods well known in the art.

[0021] The reagents used in the following examples were purchased from common commercial sources, and the experimental operations and experimental conditions not specified were referred to the conventional operations and conventional conditions in the art.

[0022] The specific implementation of the present invention is described below in conjunction with specific embodiments and drawings.

[0023] <Example>

[0024] This embodiment provides a waste soybean shell-derived porous carbon@VS2 composite material (SHVS), and the preparation steps are as follows:

[0025] Step S1, pre-treating edamame shells to obtain pre-treated edamame shells, the specific process is:

[0026] The edamame shells were ultrasonically cleaned with deionized water and anhydrous ethanol for 3 times, each time for 10 minutes, and placed in a 60°C oven for drying for 24 hours to obtain pretreated edamame shells;

[0027] Step S2, heat-treating the pretreated edamame hulls in an inert gas to obtain heat-treated edamame hulls, the specific process is:

[0028] The pretreated soybean shells were heat treated in an argon atmosphere at a temperature of 700°C for 120 min at a heating rate of 5°C / min to obtain heat treated soybean shells, which were then cooled to room temperature.

[0029] Step S3, dissolving 2.4 g of thioacetamide, 0.8 g of ammonium metavanadate, and 10 ml of aqueous ammonia in 50 ml of deionized water, and stirring for 10 min to obtain a mixed solution;

[0030] Step S4, adding the heat-treated edamame shells into the mixed solution, performing hydrothermal treatment, washing and drying to obtain the waste edamame shell-derived porous carbon@VS2 composite material, the specific process is:

[0031] 300 mg of heat-treated edamame shell was added to the mixed solution, stirred for 30 min, and then poured into a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and heated to 160 °C at a heating rate of 5 °C / min in a muffle furnace for hydrothermal treatment. The hydrothermal treatment time was 20 h, and the sample was cooled to room temperature. The obtained sample was washed three times with deionized water and anhydrous ethanol, respectively, and dried in a vacuum oven at 60 °C for 24 h to obtain the waste edamame shell-derived porous carbon@VS2 composite material (SHVS).

[0032] <Comparative Example 1>

[0033] This embodiment provides a pure vanadium disulfide absorbing material (PVS), and the preparation steps are as follows:

[0034] Step S1, dissolving 2.4 g of thioacetamide, 0.8 g of ammonium metavanadate, and 10 ml of aqueous ammonia in 50 ml of deionized water, and stirring for 10 min to obtain a mixed solution;

[0035] Step S2, pour the mixed solution into a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, heat it to 160° C. at a heating rate of 5° C. / min in a muffle furnace for hydrothermal treatment, the hydrothermal treatment time is 20 h, cool it to room temperature, wash the obtained sample with deionized water and anhydrous ethanol for 3 times, place it in a vacuum oven at 60° C. and dry it for 24 h to obtain pure vanadium disulfide absorbing material (PVS).

[0036] <Comparative Example 2>

[0037] This embodiment provides a pure biomass-derived porous carbon absorbing material (PSH), the preparation steps of which are as follows:

[0038] Step S1, ultrasonically cleaning the edamame hulls with deionized water and anhydrous ethanol for 3 times, each cleaning for 10 minutes, and placing them in a 60° C. oven for drying for 24 hours to obtain pretreated edamame hulls;

[0039] Step S2, heat treating the pretreated edamame shell in an argon atmosphere at a temperature of 700°C for 120 min at a heating rate of 5°C / min, cooling to room temperature, washing the obtained sample with deionized water and anhydrous ethanol for 3 times, respectively, and drying it in a vacuum oven at 60°C for 24 h to obtain a pure biomass-derived porous carbon absorbing material (PSH).

[0040] The SHVS prepared in the above embodiment, the PVS prepared in comparative example 1, and the PSH prepared in comparative example 2 were characterized by XRD, SEM, and wave absorption performance test. The wave absorption performance test characterization is to measure the electromagnetic parameters of the complex dielectric constant and complex magnetic permeability of the electromagnetic parameters by the coaxial line method using the Siyi 3672B-S vector network analyzer in the frequency range of 2 to 18 GHz. Preparation of test samples: The object to be tested is evenly dispersed in paraffin with a mass percentage of 25%, and then pressed into a ring-shaped part with an outer diameter of 7.0 mm and an inner diameter of 3.04 mm. The test characterization results are as follows:

[0041] Figure 1 SHVS prepared in the embodiment of the present invention, PVS prepared in Comparative Example 1, and PSH prepared in Comparative Example 2 are XRD patterns. Figure 1It can be seen that the PVS prepared in Comparative Example 1 is VS2, the PSH prepared in Comparative Example 2 is a typical amorphous carbon diffraction peak, and the SHVS prepared in the example is composed of amorphous carbon and VS2. The positions of each peak and the corresponding PDF cards are marked in the figure.

[0042] Figure 2 SHVS prepared in the embodiment of the present invention, PVS prepared in Comparative Example 1, and PSH prepared in Comparative Example 2 are SEM and EDS images, wherein: Figure 2 (a) and (e) are SEM images of PVS prepared in Comparative Example 1; Figure 2 (b) and (f) are SEM images of PSH prepared in Comparative Example 2; Figure 2 (c), (d), (g) and (h) are SEM images of SHVS prepared in the embodiments of the present invention; Figure 2 (i) is the EDS diagram of SHVS prepared in the embodiment of the present invention. Figure 2 It can be seen that the PVS prepared in Comparative Example 1 is flower-shaped, composed of several sheet-shaped VS2, with a diameter of about 20 μm. The PSH prepared in Comparative Example 2 has an uneven surface and a porous interior. The SHVS prepared in Example 1 has flower-shaped VS2 uniformly covering the porous carbon surface and cross-section.

[0043] Figure 3 SHVS prepared in the embodiment of the present invention, PVS prepared in Comparative Example 1, and PSH prepared in Comparative Example 2 are shown in the figure. Figure 3 a in the figure is a graph showing the wave absorption performance of PVS obtained in Comparative Example 1; Figure 3 b is a graph showing the wave absorption performance of the PSH obtained in Comparative Example 2; Figure 3 c in FIG. 1 is a diagram showing the wave absorption performance of the SHVS prepared in an embodiment of the present invention.

[0044] The wave absorption performance parameters and heat treatment process of the SHVS prepared in the embodiment of the present invention, the PVS prepared in Comparative Example 1 and the PSH prepared in Comparative Example 2 are listed in Table 1.

[0045] Table 1

[0046]

[0047] RL is the reflection loss; RL min Minimum reflection loss.

[0048] Depend on Figure 3As shown in Table 1, the thickness range of PVS prepared in Comparative Example 1 is 1.0-5.0 mm. When the frequency is 11.32 GHz and the thickness is 2.5 mm, the RLmin is -33.25 dB, and its absorption bandwidth is 3.28 GHz at this thickness. The thickness range of PSH prepared in Comparative Example 2 is 1.0-5.0 mm, and the wave absorption performance is poor within the measured range. When the thickness is 1.5 mm and the frequency is 13.52 GHz, the RLmin is -14.55 dB, and the corresponding absorption bandwidth is 3.38 GHz. The thickness range of SHVS prepared in the embodiment is 1.0-5.0 mm. When the frequency is 14.56 GHz and the thickness is 1.7 mm, the RLmin is -62.74 dB, and its absorption bandwidth (RL<-10 dB) is 6.04 GHz at this thickness. It can be seen that the SHVS prepared in the embodiment shows excellent wave absorbing performance in a thinner matching thickness (d=1.7 mm) and a wider frequency range (Ku band), and has great application potential in electromagnetic wave absorption.

[0049] The above is a detailed description of the embodiments, which is convenient for those skilled in the art to correctly understand and use the present invention. Any improvements or modifications to the technical solutions obtained by those skilled in the art based on the present invention on the basis of the prior art, without innovative work, only through analysis, analogy or limited enumeration, etc., should be within the scope of protection determined by the claims.

Claims

1. A method for preparing a porous carbon@VS2 composite material derived from waste soybean shells, characterized in that: The steps include: Step S1, pre-treating edamame hulls to obtain pre-treated edamame hulls; Step S2, heat-treating the pretreated edamame hulls in an inert gas to obtain heat-treated edamame hulls; Step S3, dissolving thioacetamide, ammonium metavanadate, and aqueous ammonia in deionized water to obtain a mixed solution; Step S4, adding the heat-treated soybean shells to the mixed solution, performing hydrothermal treatment, washing, and drying to obtain the waste soybean shell-derived porous carbon@VS2 composite material, Wherein, the mass ratio of the heat-treated soybean shell, the thioacetamide, the ammonium metavanadate, the ammonia water and the deionized water is 1:(7-9):(2-3):(30-35):(165-170), The pretreatment process in step S1 is: washing the soybean shells with deionized water and anhydrous ethanol, drying, The heat treatment temperature in step S2 is 650-750°C, the time is 100-150 min, and the heating rate is 3-8°C / min. In step S4, the temperature of the hydrothermal treatment is 150-200°C, the time is 18-24 h, the heating rate is 3-8°C / min, the washing agent is deionized water and anhydrous ethanol, and the drying temperature is 50-80°C.

2. The method for preparing the waste soybean husk-derived porous carbon@VS2 composite material according to claim 1, characterized in that: in, The inert gas in step S2 is argon.

3. A porous carbon@VS2 composite material derived from discarded soybean shells, characterized in that: The porous carbon@VS2 composite material derived from waste edamame shells is prepared by the preparation method of claim 1 or 2.

4. The waste soybean husk derived porous carbon@VS2 composite material according to claim 3, characterized in that: The waste edamame shell-derived porous carbon@VS2 composite material is applied in products for electromagnetic wave absorption.

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