Composite material with Co9S8 / MoS2 bimetallic sulfide heterojunction and preparation method and application thereof

Abstract

The invention relates to a composite material with Co9S8 / MoS2 bimetallic sulfide heterojunction and a preparation method and application thereof.The preparation method of the composite material comprises the following steps that S1, a cobalt source, dimethylimidazole and hexadecyl trimethyl ammonium bromide are weighed and added into deionized water, stirring and dissolving are conducted, a mixed solution is obtained, then standing, washing and drying are conducted, and ZIF-67 precursor powder is obtained; s2, adding the ZIF-67 precursor powder obtained in S1, a molybdenum source and a sulfur source into deionized water, uniformly stirring, transferring into a reaction kettle for heating reaction, cooling to room temperature, collecting a reaction product, washing, and drying overnight; and S3, placing the sample dried in the step S2 in a reducing atmosphere, and carrying out calcination treatment to obtain the Co9S8 / MoS2 composite material, namely a target product. Compared with the prior art, the composite material provided by the invention has the advantages that the reflection loss intensity of-55.06 dB is realized under the ultrathin thickness of 1.50 mm, and the effective absorption bandwidth reaches 5.28 GHz. The work provides a new view angle for the development of low-density and high-efficiency electromagnetic wave absorbers.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic wave absorbing materials, and relates to a composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of gigahertz (GHz) high-frequency communication technology, the increasingly upgraded electromagnetic wave pollution has become a major destructive factor for the normal operation of precision instruments and poses a potential threat to human health. Although electromagnetic wave absorbers such as ferrite, metal powder and carbon material have certain attenuation effect, their wide application is limited by inherent defects such as poor impedance matching, fixed absorption frequency range and narrow frequency coverage. In recent years, transition metal sulfides have attracted widespread attention in electromagnetic wave absorption due to their unique dielectric properties and adjustable band gap, and in particular, building bimetallic sulfide heterojunction is a promising strategy. The more intimate interface contact between sulfides is conducive to efficient charge transfer and improves the dielectric loss ability. Despite many advantages, it is still a challenge to precisely control the heterojunction architecture to achieve a balance between dielectric loss and impedance matching.

[0003] Chinese patent CN202211079810.1 provides a hollow urchin-shaped cobalt-based sulfide composite wave-absorbing material and a preparation method thereof, which is composed of hollow urchin-shaped Co9S8 and CoO nanosheets grown in situ on the surface thereof. The preparation method comprises the following steps: I: synthesis of urchin-shaped Co precursor; II: conversion of the Co precursor in step I into hollow urchin-shaped Co9S8 / Co(OH)2 under hydrothermal conditions; III: annealing treatment of the hollow urchin-shaped Co9S8 / Co(OH)2 composite material obtained in step II to prepare a hollow urchin-shaped Co9S8 / CoO composite wave-absorbing material. Since CoO is a wide-bandgap insulator, its intrinsic conductivity and dielectric loss ability are weak, which leads to low interface charge transfer efficiency when it is combined with metallic Co9S8, and the polarization relaxation effect is limited, often requiring to increase the material thickness (usually >2.0 mm) to improve the electromagnetic wave absorption performance. SUMMARY

[0004] The purpose of the present application is to provide a composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction and a preparation method and application thereof, which realizes high-efficiency electromagnetic wave absorption effect.

[0005] The purpose of the present application can be achieved by the following technical solutions: In a first aspect, the present application provides a preparation method of a composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction, comprising the following steps: S1, weigh cobalt source, dimethylimidazole, cetyltrimethylammonium bromide into deionized water, stir and dissolve to obtain a mixed solution, then stand, wash and dry to obtain ZIF-67 precursor powder; S2, add the ZIF-67 precursor powder obtained in S1, a molybdenum source and a sulfur source into deionized water, stir uniformly, then transfer into a reaction kettle for heating reaction, then cool to room temperature, collect the reaction product and wash and dry overnight; S3, place the dried sample in S2 in a reducing atmosphere for calcination treatment to obtain a Co9S8 / MoS2 composite material, which is the target product.

[0006] Further, in S1, the cobalt source is cobalt nitrate or a hydrate thereof.

[0007] Further, in S1, the addition amount ratio of the cobalt source, dimethylimidazole and cetyltrimethylammonium bromide is (0.0005-0.0015) mol:(0.005-0.006) mol:5 mg.

[0008] Further, in S2, the molybdenum source is sodium molybdate or a hydrate thereof, and the sulfur source is thiourea.

[0009] Further, in S2, the mass ratio of the ZIF-67 precursor powder, the molybdenum source and the sulfur source is 0.04:(0.1-0.2):(0.15-0.6).

[0010] Further, in S2, the heating reaction temperature is 190-210℃, and the time is 22-26 h.

[0011] Further, in S3, the calcination treatment temperature is 500-700℃, and the time is 2-4 h.

[0012] Further, in S3, the reducing atmosphere is provided by H2 / Ar, wherein the volume fraction of H2 is 5%.

[0013] In a second aspect, the present application provides a composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction, which is prepared by the preparation method according to any one of the above. The Co9S8 / MoS2 bimetallic sulfide heterojunction constructed by the present application can form a heterojunction structure with better band matching and stronger built-in electric field, thereby increasing the interface polarization capacity. In addition, by accurately adjusting the Mo / S ratio, the impedance matching property is optimized. The final composite material realizes a reflection loss capacity of-55.06 dB under the ultra-thin thickness of 1.5 mm, effectively overcoming the deficiencies of traditional sulfide / oxide composite materials in interface engineering, structure design and performance control.

[0014] In a third aspect, the present application provides a use of a composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction in the preparation of an electromagnetic wave absorbing material.

[0015] Compared with the prior art, the present application has the following advantages: (1) The in-situ growth of MoS2 nanosheets forms a nano-flower-like structure, effectively promoting multiple reflection and scattering of electromagnetic waves, thereby improving impedance matching. At the same time, the accurate control of the Mo / S ratio optimizes the electromagnetic performance of the Co9S8 / MoS2 heterojunction, further enhancing the impedance matching of the CMS composite material.

[0016] (2) The unbalanced charge distribution in the Co9S8 / MoS2 heterojunction interface region generates an internal electric field, driving the dynamic balance between carrier drift and diffusion, and triggering a strong polarization relaxation effect, thereby dissipating electromagnetic energy.

[0017] (3) Benefiting from the bimetallic sulfide heterojunction engineering, the Co9S8 / MoS2 composite material provided by the present application exhibits excellent electromagnetic energy dissipation, reaching -55.06 dB at an ultra-thin thickness of 1.5 mm. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 XRD pattern of the ZIF-67 cube prepared in Example 1.

[0019] Figure 2 SEM pattern of the ZIF-67 cube prepared in Example 1.

[0020] Figure 3 XRD pattern of the CoS2 / MoS2 material prepared in S2 of Example 1-4.

[0021] Figure 4 SEM pattern of the CoS2 / MoS2 material prepared in S2 of Example 1-4.

[0022] Figure 5 XRD pattern of the Co9S8 / MoS2 material prepared in S3 of Example 1-4.

[0023] Figure 6 SEM pattern of the Co9S8 / MoS2 material prepared in S3 of Example 1-4.

[0024] Figure 7 XRD pattern of the Co3S4 / NiS material prepared in S2 of Comparative Example 2.

[0025] Figure 8 SEM pattern of the Co9S8 / Ni3S2 material prepared in S3 of Comparative Example 2.

[0026] Figure 9 Electromagnetic parameter map of the Co9S8 / MoS2 material prepared for S3 in Examples 1-4.

[0027] Figure 10 Absorbing performance curve of S3 in Examples 1-4.

[0028] Figure 11 Absorbing performance curve of Example 3 and Comparative Example 1.

[0029] Figure 12 Absorbing performance curve of Example 3 and Comparative Example 2. DETAILED DESCRIPTION

[0030] The application will be described in greater detail with reference to the drawings and specific embodiments. The embodiments are implemented on the premise of the technical scheme of the application, and give detailed implementation modes and specific operation processes, but the protection scope of the application is not limited to the following embodiments.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0032] The selection scope of the terms "and / or", "or / and", "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, including any two related listed items, any more related listed items, or all related listed items. It should be noted that when at least two conjunctions selected from "and / or", "or / and", "and / or" are combined to connect at least three items, it should be understood that in the present application, the technical scheme undoubtedly includes the technical scheme connected by "logical and", and also undoubtedly includes the technical scheme connected by "logical or".

[0033] In the present application, in the technical features described in an open manner, both the closed technical scheme consisting of the listed features and the open technical scheme containing the listed features are included.

[0034] In this application, when referring to numerical intervals, unless otherwise specified, the numerical intervals are considered continuous and include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Further, when a range is provided, it is intended to include every integer within the range, inclusive of the integers at the upper and lower limits of the range. In addition, many aspects are described in terms of sequences, protocols, and other functional descriptions. Unless otherwise specified, the nomenclature utilized in connection with, and the procedures involved in, the described aspects are intended to be consistent with the nomenclature and procedures as set forth in the Guide for the Care and Use of Laboratory Animals, National Academy of Sciences (2000) and the Chemical Abstracts Service Source Index, which are both incorporated herein by reference. Unless otherwise indicated, all ranges are inclusive of the endpoints.

[0035] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with any other lower limit to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. Further, each individual disclosed point or single numerical value can be combined with any other point or single numerical value as a lower limit or an upper limit to form a range not explicitly recited.

[0036] In this application, unless otherwise specified, the temperature parameters allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows fluctuations within the accuracy of the instrument control. Fluctuations within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0037] In this application, "suitable", "suitable manner", "any suitable manner", and the like, are used to refer to the ability to implement the technical solutions of the application, solve the technical problems of the application, and achieve the intended technical effects of the application.

[0038] In this application, "further", "still further", "in particular", and the like are used to describe purposes and indicate differences in content, but should not be understood as limiting the scope of protection of the application.

[0039] In this application, "optionally", "optional", and "optional" mean that it can or can not be present, i.e., it is selected from either of the two parallel schemes "yes" or "no". If there are multiple "optional" in a technical solution, unless otherwise specified, and there is no contradictory or mutual restrictive relationship, each "optional" is independent.

[0040] In the description of the application, "multiple" means at least two, for example, two, three, etc., unless otherwise specifically limited.

[0041] Unless otherwise specified, all formulations and tests in this application occur in an environment of 25°C.

[0042] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0044] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0045] In the following examples, 2-methylimidazole, cobalt nitrate hexahydrate, and hexadecyltrimethylammonium bromide were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Thiourea and sodium molybdate dihydrate were purchased from Sinopharm Chemical Reagent Co., Ltd. Unless otherwise specified, all other raw materials or processing techniques are commercially available and conventional in the art.

[0046] Example 1 A method for preparing a composite material with a Co9S8 / MoS2 bimetallic sulfide heterostructure, comprising the following steps: S1: 0.001 mol cobalt nitrate hexahydrate and hexadecyltrimethylammonium bromide were dissolved in 10 mL of deionized water and magnetically stirred. The resulting mixture was then rapidly added to 70 mL of an aqueous solution containing 0.0055 mol dimethylimidazole. The mixture was stirred at room temperature for 30 min and allowed to stand for 2 h. The product was collected by centrifugation, washed several times with ethanol, and dried under vacuum at 70°C overnight to obtain ZIF-67 cubes.

[0047] S2: 0.04 mg ZIF-67 cubes were dispersed in 25 mL of deionized water, then 0.15 g sodium molybdate dihydrate and 0.15 g thiourea were added, and the mixture was stirred for 1 h. The mixture was transferred to a 50 mL polytetrafluoroethylene autoclave and heated at 200°C for 24 h. After cooling to room temperature, the mixture was washed three times with ethanol and deionized water, and then vacuum dried at 60°C for 12 h. The final CoS2 / MoS2 composite material was obtained.

[0048] The sample prepared by S3:S2 was calcined at 600 °C for 3 h in an H2 / Ar atmosphere. The final product was a Co9S8 / MoS2 composite material.

[0049] Example 2 Compared with Example 1, most of the steps are the same, except for step S2: 0.04 mg of ZIF-67 cubes were dispersed in 25 mL of deionized water, followed by the addition of 0.15 g of sodium molybdate dihydrate and 0.30 g of thiourea, and the mixture was stirred for 1 h. The mixture was then transferred to a 50 mL polytetrafluoroethylene autoclave and heated at 200°C for 24 h. After cooling to room temperature, the mixture was washed three times with ethanol and deionized water, and then vacuum dried at 60°C for 12 h. The final CoS2 / MoS2 composite material was obtained.

[0050] Example 3 Compared with Example 1, most of the steps are the same, except for step S2: 0.04 mg ZIF-67 cubes were dispersed in 25 mL of deionized water, followed by the addition of 0.15 g sodium molybdate dihydrate and 0.45 g thiourea, and the mixture was stirred for 1 h. The mixture was then transferred to a 50 mL polytetrafluoroethylene autoclave and heated at 200°C for 24 h. After cooling to room temperature, the mixture was washed three times with ethanol and deionized water, and then vacuum dried at 60°C for 12 h. The final CoS2 / MoS2 composite material was obtained.

[0051] Example 4 Compared with Example 1, most of the steps are the same, except for step S2: 0.04 mg ZIF-67 cubes were dispersed in 25 mL of deionized water, followed by the addition of 0.15 g sodium molybdate dihydrate and 0.60 g thiourea, and the mixture was stirred for 1 h. The mixture was then transferred to a 50 mL polytetrafluoroethylene autoclave and heated at 200°C for 24 h. After cooling to room temperature, the mixture was washed three times with ethanol and deionized water, and then vacuum dried at 60°C for 12 h. The final CoS2 / MoS2 composite material was obtained.

[0052] Comparative Example 1 Compared with Example 3, most of them are the same, and step S3 is not performed.

[0053] Comparative Example 2 It is largely the same as Example 3, except that sodium molybdate dihydrate is replaced with an equimolar amount of nickel nitrate hexahydrate.

[0054] X-ray electron diffraction (XRD) was performed on the ZIF-67 cube precursor prepared in Example 1. The test results are as follows.Figure 1 As shown, the XRD pattern of the ZIF-67 cube prepared in this invention matches well with the results of crystallographic data simulation. Scanning electron microscopy (SEM) testing yielded the following results: Figure 2 As shown, ZIF-67 exhibits a cubic morphology.

[0055] XRD tests were performed on the CoS2 / MoS2 materials prepared by S2 in Examples 1-4. The test results are as follows: Figure 3 As shown, the different diffraction peaks at 2θ = 14.3°, 33.5°, 39.5°, and 60.1° in Examples 1-4 correspond to the (002), (101), (103), and (008) crystal planes of the 2H-MoS2 phase, respectively. Furthermore, the diffraction peaks observed at 2θ = 32.3°, 36.2°, and 54.9° also correspond to the (200), (210), and (311) crystal planes of CoS2. Comparing Examples 1-4, it can be observed that the intensity of the derived peaks corresponding to MoS2 increases with increasing thiourea content. Therefore, by controlling the thiourea content to change the Mo / S molar ratio, the relative content between CoS2 and MoS2 can be effectively adjusted.

[0056] SEM analysis was performed on the CoS2 / MoS2 materials prepared by S2 in Examples 1-4. The test results are as follows: Figure 4 As shown, the CoS2 / MoS2 materials in Examples 1-4 exhibit a nanoflower-like structure, which consists of MoS2 nanosheets grown on the surface of ZIF-67 derived CoS2 cubes. Furthermore, with increasing thiourea content, the number of MoS2 nanosheets acting as "petals" increases, resulting in a denser and more complex flower-like morphology in Examples 3 and 4.

[0057] XRD tests were performed on the Mo9S8 / MoS2 materials prepared by S3 in Examples 1-4. The test results are as follows: Figure 5 As shown, during the high-temperature pyrolysis of S3, CoS2 undergoes a phase transition to form the more stable Co9S8. The diffraction peaks at 2θ = 29.8°, 31.2°, 47.6° and 52.1° correspond to the (311), (222), (511) and (440) crystal planes of Co9S8.

[0058] SEM analysis was performed on the Mo9S8 / MoS2 materials prepared by S3 in Examples 1-4. The test results are as follows: Figure 6 As shown, the unique nanoflower structure is well preserved after the high-temperature pyrolysis process, which is beneficial to promoting multiple reflections and scattering of incident electromagnetic waves.

[0059] The sample prepared in Comparative Example 2 was subjected to XRD testing. The test results are as follows: Figure 7As shown, when sodium molybdate dihydrate is replaced with an equimolar amount of nickel nitrate hexahydrate, the hydrothermal reaction yields NiS and Co3S4 products. The diffraction peaks at 2θ = 18.46°, 32.25°, and 48.93° correspond to the (110), (300), and (131) crystal planes of NiS. The diffraction peaks at 2θ = 16.29°, 31.49°, and 55.13° correspond to the (111), (311), and (440) crystal planes of Co3S4. The XRD results of Comparative Example 2 after high-temperature pyrolysis are shown below. Figure 8 As shown, NiS transforms into Ni3S2, and Co3S4 transforms into Co9S8.

[0060] The electromagnetic properties of the materials prepared in S3 in Examples 1-4 were analyzed using a vector network analyzer (VNA, Agilent N5224B, 2-18 GHz). The test results are as follows: Figure 9 As shown, the dielectric constant of the material decreases with increasing thiourea content. Specifically, the real part of the dielectric constant ( ε' The average value of the dielectric constant gradually decreases from 13.61 to 8.96 in the range of 2-18 GHz, and the imaginary part of the dielectric constant ( ε" The average value decreased from 6.38 to 2.34. By controlling the thiourea content and changing the Mo / S molar ratio, the electromagnetic parameters of the composite material can be effectively adjusted, and the impedance matching can be improved.

[0061] Figure 10 The graphs show the microwave absorption performance of the materials prepared by S3 in Examples 1-4, and the RL values ​​of Example 1 at 11.92 GHz with a thickness of 1.7 mm. min The absorption intensity was only -14.75 dB. Example 2 showed improved absorption, achieving an RL of -29.06 dB at 14.42 GHz and a thickness of 1.5 mm. min Example 3 exhibits excellent electromagnetic wave absorption capability, RL min The absorption value reached -55.06 dB at 15.84 GHz with a thickness of only 1.5 mm. In contrast, the absorption of Example 4 decreased due to the continuous increase in MoS2 content, with an RL value of -55.06 dB at 10.32 GHz. min It is only -17.26 dB.

[0062] Figure 11 The graph shows a comparison of the electromagnetic parameters and absorption performance of Example 3 and Comparative Example 1. The results show that Example 3, after high-temperature carbonization, has a higher dielectric constant and stronger dielectric loss capability. The magnitude of the attenuation constant also verifies this view. Comparing the absorption performance curves, Example 3, due to the construction of a Co9S8 / MoS2 bimetallic sulfide heterojunction, synergistically enhances the interface polarization effect by optimizing the space charge distribution and accelerating charge carrier migration.

[0063] Figure 12 The graph shows a comparison of the electromagnetic parameters and absorption performance of Example 3 and Comparative Example 2. The results show that Comparative Example 2, after high-temperature carbonization, has a higher dielectric constant and stronger dielectric loss capability. However, due to the high conductivity of Ni3S2, the impedance matching is poor, and it cannot completely absorb electromagnetic waves. Comparing the absorption performance curves, Example 3 achieves a perfect balance between interface loss and impedance matching, jointly improving the electromagnetic wave absorption capability.

[0064] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a composite material having a Co9S8 / MoS2 bimetallic sulfide heterojunction, characterized by, The method comprises the following steps: S1, a cobalt source, dimethylimidazole, and cetyltrimethylammonium bromide are weighed and added to deionized water, stirred and dissolved to obtain a mixed solution, and then the mixed solution is left to stand, washed, and dried to obtain ZIF-67 precursor powder; S2, the ZIF-67 precursor powder obtained in S1, a molybdenum source, and a sulfur source are added to deionized water, stirred uniformly, and then transferred to a reaction kettle for heating reaction, and then cooled to room temperature, and the reaction product is collected and washed and dried overnight; S3, the dried sample in S2 is placed in a reducing atmosphere for calcination treatment to obtain a Co9S8 / MoS2 composite material, which is the target product.

2. The method for preparing a composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction according to claim 1, characterized in that, In S1, the cobalt source is cobalt nitrate or a hydrate thereof.

3. The method for preparing a composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction according to claim 1, characterized in that, In S1, the addition amount ratio of the cobalt source, dimethylimidazole, and cetyltrimethylammonium bromide is (0.0005-0.0015) mol:(0.005-0.006) mol:5 mg.

4. The method of claim 1, wherein the composite material having a Co9S8 / MoS2 bimetallic sulfide heterojunction is prepared by the steps of: In S2, the molybdenum source is sodium molybdate or a hydrate thereof, and the sulfur source is thiourea.

5. The method of claim 1, wherein the composite material having a Co9S8 / MoS2 bimetallic sulfide heterojunction is prepared by the steps of: In S2, the mass ratio of the ZIF-67 precursor powder, the molybdenum source, and the sulfur source is 0.04:(0.1-0.2):(0.15-0.6).

6. The method of claim 1, wherein the composite material having a Co9S8 / MoS2 bimetallic sulfide heterojunction is prepared by the steps of: In S2, the heating reaction temperature is 190-210℃, and the time is 22-26 h.

7. The method of claim 1, wherein the composite material having a Co9S8 / MoS2 bimetallic sulfide heterojunction is prepared by the steps of: In S3, the calcination treatment temperature is 500-700℃, and the time is 2-4 h.

8. The method of claim 1, wherein the composite material having a Co9S8 / MoS2 bimetallic sulfide heterojunction is prepared by the steps of: In S3, the reducing atmosphere is provided by H2 / Ar, wherein the volume fraction of H2 is 5%.

9. A composite material having a Co9S8 / MoS2 bimetallic sulfide heterojunction, characterized in that, The method is prepared by the preparation method of any one of claims 1-8.

10. Use of the composite material with a Co9S8 / MoS2 bimetallic sulfide heterojunction according to claim 9 in the preparation of electromagnetic wave absorbing materials.

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