Preparation method of few-layer molybdenum sulfide and supported few-layer molybdenum sulfide

Abstract

The invention discloses a preparation method of few-layer molybdenum sulfide and supported few-layer molybdenum sulfide, and belongs to the technical field of catalysts. The few-layer molybdenum sulfide or the supported few-layer molybdenum sulfide is prepared by taking MoO3 or supported MoO3 as a raw material and performing in-situ vulcanization in a mixed atmosphere of methane, hydrogen sulfide and hydrogen. The preparation method provided by the invention is high in repeatability and good in universality, and the few-layer molybdenum sulfide and the supported few-layer molybdenum sulfide can be prepared by using various supported or bulk-phase molybdenum oxides. According to the preparation method provided by the invention, the problem that molybdenum sulfide obtained by a conventional gas-phase vulcanization molybdenum sulfide preparation scheme is too thick is well solved. The preparation method provided by the invention is simple and effective in process, the number of obtained molybdenum sulfide layers is small, and the preparation method can be applied to various fields and is suitable for industrial production and market popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a preparation method of a few-layer molybdenum sulfide and a supported few-layer molybdenum sulfide. Background Art

[0002] The extraordinary performance of two-dimensional materials has opened up a new field for the development of low-dimensional materials. Their unique physical and chemical properties and excellent optoelectronic properties have attracted widespread attention. Transition metal sulfide (TMDC) is another new type of two-dimensional material discovered after graphene. TMDC forms an X-M-X hexagonal structure through covalent bonds, where X is Te, Se, S, etc., and M is a VI, V, IV group element. TMDC is a sandwich structure with two layers of X atoms sandwiching a layer of M atoms, and the layers interact through van der Waals forces. Compared with graphene, TMDC has a natural band gap, among which molybdenum disulfide (MoS2) has an intercalation structure. As the number of layers decreases, the band gap becomes larger and larger. When it becomes a single layer, its band gap changes from an indirect band gap (band gap width is about 1.2eV) to a direct band gap (band gap width is about 1.9eV). Therefore, MoS2 has application potential in field effect transistors, photodetectors, integrated circuits, and memory. However, the preparation of high-performance few-layer molybdenum sulfide or supported few-layer molybdenum sulfide is difficult, and the art urgently needs to develop a method for preparing high-performance few-layer molybdenum sulfide or supported few-layer molybdenum sulfide with a simple process. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a few-layer molybdenum sulfide and a supported few-layer molybdenum sulfide. The few-layer molybdenum sulfide or supported few-layer molybdenum sulfide is prepared by in-situ sulfidation in a mixed atmosphere of methane, hydrogen sulfide and hydrogen using MoO3 or supported MoO3 as a raw material.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] One of the technical solutions of the present invention is to provide a method for preparing a few-layer molybdenum sulfide, comprising the following steps: in-situ sulfiding MoO3 in a mixed atmosphere of methane, hydrogen sulfide and hydrogen to obtain the few-layer molybdenum sulfide.

[0006] The few-layer molybdenum sulfide described in the present invention refers to molybdenum sulfide having an average number of layers less than 3.

[0007] Preferably, the volume ratio of methane, hydrogen sulfide and hydrogen is 2:1:7.

[0008] Preferably, the temperature of the in-situ vulcanization is not less than 700°C.

[0009] Since the sulfurization temperature of MoO3 is 700°C, the in-situ sulfurization temperature of the present invention is not less than 700°C.

[0010] The second technical solution of the present invention: A method for preparing supported few-layer molybdenum sulfide, comprising the following steps: in-situ sulfiding supported MoO3 in a mixed atmosphere of methane, hydrogen sulfide and hydrogen to obtain supported few-layer molybdenum sulfide.

[0011] Optionally, the carrier material of the supported MoO3 may be SiO2, Al2O3, etc.

[0012] Preferably, the volume ratio of methane, hydrogen sulfide and hydrogen is 2:1:7.

[0013] Preferably, the temperature of the in-situ vulcanization is 700-850°C.

[0014] The beneficial technical effects of the present invention are as follows:

[0015] The preparation method provided by the present invention has high repeatability and good universality, and can use various supported or bulk molybdenum oxides to prepare few-layer molybdenum sulfide and supported few-layer molybdenum sulfide.

[0016] The preparation method provided by the present invention effectively solves the problem that the molybdenum sulfide obtained by the conventional gas phase sulfidation method for preparing molybdenum sulfide is too thick.

[0017] The preparation method provided by the invention is simple and effective, the number of obtained molybdenum sulfide layers is small, and the method can be applied to various fields and is suitable for industrial production and market promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 XRD patterns of the few-layer molybdenum sulfide and supported few-layer molybdenum sulfide prepared in Examples 1-3.

[0019] Figure 2 These are Raman spectra of the few-layer molybdenum sulfide or supported few-layer molybdenum sulfide prepared in Examples 1 to 3 and Comparative Examples 1 to 3, wherein A is the Raman spectrum of the Al2O3-supported few-layer molybdenum sulfide prepared in Example 3 and Comparative Example 3; B is the Raman spectrum of the SiO2-supported few-layer molybdenum sulfide prepared in Example 2 and Comparative Example 2; and C is the Raman spectrum of the few-layer molybdenum sulfide prepared in Example 1 and Comparative Example 1.

[0020] Figure 3 TEM images of the supported few-layer molybdenum sulfide prepared in Example 2-3 and Comparative Example 2-3, wherein A is the TEM image of the Al2O3 supported few-layer molybdenum sulfide prepared in Comparative Example 3, B is the TEM image of the SiO2 supported few-layer molybdenum sulfide prepared in Comparative Example 2, C is the TEM image of the Al2O3 supported few-layer molybdenum sulfide prepared in Example 3, and D is the TEM image of the SiO2 supported few-layer molybdenum sulfide prepared in Example 2. DETAILED DESCRIPTION

[0021] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0022] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0023] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0024] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0025] The SiO2 and MoO3 used in the examples and comparative examples of the present invention are commercially available materials.

[0026] The Al2O3 used in the examples and comparative examples of the present invention was prepared by the following method:

[0027] After dissolving 6.44g aluminum nitrate and 9.4g urea in 190g distilled water, adding ammonia water to adjust the pH to 4, and then treating at a constant temperature of 100°C in a high-pressure reactor for 48h, finally centrifugally washing, drying at 100°C, and calcining at 600°C for 2h to obtain the product.

[0028] Example 1

[0029] Preparation of few-layer molybdenum sulfide:

[0030] 1g MoO3 is placed in V 甲烷 :V 硫化氢 :V 氢气 =2:1:7 atmosphere at 800℃ for 3h to obtain a few layers of molybdenum sulfide.

[0031] Example 2

[0032] Preparation of SiO2-supported few-layer molybdenum sulfide:

[0033] 0.184 g of ammonium heptamolybdate tetrahydrate was dissolved in 1.5 g of deionized water, 1 g of SiO2 was added, and then dried at 120 °C for 12 h, and then calcined at 550 °C for 4 h to obtain SiO2-supported MoO3;

[0034] 1g SiO2-loaded MoO3 was placed at V 甲烷 :V 硫化氢 :V 氢气 =2:1:7 atmosphere at 800°C for 3h to obtain SiO2-supported few-layer molybdenum sulfide.

[0035] Example 3

[0036] Preparation of Al2O3-supported few-layer molybdenum sulfide:

[0037] 0.184 g of ammonium heptamolybdate tetrahydrate was dissolved in 1.5 g of deionized water, 1 g of Al2O3 was added, and then dried at 120°C for 12 h, and then calcined at 550°C for 4 h to obtain Al2O3-supported MoO3;

[0038] 1 g of MoO3 loaded with Al2O3 was placed on V 甲烷 :V 硫化氢 :V 氢气 =2:1:7 atmosphere at 800°C for 3h to obtain Al2O3-supported few-layer molybdenum sulfide.

[0039] Comparative Example 1

[0040] Preparation of few-layer molybdenum sulfide:

[0041] Compared with Example 1, the only difference is that the in-situ sulfurization atmosphere is replaced by V 硫化氢 :V 氢气 =1:7.

[0042] Comparative Example 2

[0043] Preparation of SiO2-supported few-layer molybdenum sulfide:

[0044] Compared with Example 2, the only difference is that the in-situ sulfurization atmosphere is replaced by V 硫化氢 :V 氢气 =1:7.

[0045] Comparative Example 3

[0046] Preparation of Al2O3-supported few-layer molybdenum sulfide:

[0047] Compared with Example 3, the only difference is that the in-situ sulfurization atmosphere is replaced by V 硫化氢 :V 氢气 =1:7.

[0048] (1) XRD experiment

[0049] The few-layer molybdenum sulfide or supported few-layer molybdenum sulfide prepared in Examples 1-3 was subjected to scanning diffraction using a Rigaku D / Max-1200 diffractometer. The radiation source was 40 kV CuKα (λ=0.154 nm), the operating current was 30 mA, the scanning range 2θ was 10-90°, and the scanning fineness was 5° / min. The scanning results are shown in Figure 1 (Among them, MoO is the XRD curve of few-layer molybdenum sulfide, Mo-Si is the XRD curve of SiO2-supported few-layer molybdenum sulfide, and Mo-Al is the XRD curve of Al2O3-supported few-layer molybdenum sulfide).

[0050] Figure 1 It shows that all samples have obvious molybdenum sulfide peaks, indicating that the materials are well sulfurized.

[0051] (2) Ramam Experiment

[0052] Raman measurements were performed using a Raman spectrometer (LabRAM HR Evolution, HORIBA JobinYvon, France) with an excitation wavelength of 532 nm.

[0053] The Raman spectra of the few-layer molybdenum sulfide or supported few-layer molybdenum sulfide prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Figure 2 , wherein A is the Raman spectrum of the Al2O3-supported few-layer molybdenum sulfide prepared in Example 3 and Comparative Example 3; B is the Raman spectrum of the SiO2-supported few-layer molybdenum sulfide prepared in Example 2 and Comparative Example 2; C is the Raman spectrum of the few-layer molybdenum sulfide prepared in Example 1 and Comparative Example 1.

[0054] The closer the distance between the two peaks in the Raman spectrum, the fewer the number of molybdenum sulfide layers. Figure 2 It can be seen that the Raman spectrum peak spacing of all samples with methane added to the sulfiding atmosphere is narrower than that without methane, indicating that the addition of methane can further reduce the number of molybdenum sulfide layers.

[0055] (3) Transmission electron microscopy experiment

[0056] After the image benchmark was calibrated by the probe forming spherical distortion corrector, the aberration-corrected high-angle annular dark-field scanning transmission electron micrograph (HAADF-STEM) was obtained. The equipment model was JEOL JEM-F200.

[0057] The TEM images of the supported few-layer molybdenum sulfide prepared in Example 2-3 and Comparative Example 2-3 are shown in Figure 3, wherein A is the TEM image of the Al2O3-supported few-layer molybdenum sulfide prepared in Comparative Example 3, B is the TEM image of the SiO2-supported few-layer molybdenum sulfide prepared in Comparative Example 2, C is the TEM image of the Al2O3-supported few-layer molybdenum sulfide prepared in Example 3, and D is the TEM image of the SiO2-supported few-layer molybdenum sulfide prepared in Example 2.

[0058] Figure 3 It shows that the average number of layers of the Al2O3-loaded few-layer molybdenum sulfide prepared in Comparative Example 3 is 3.9, the average number of layers of the SiO2-loaded few-layer molybdenum sulfide prepared in Comparative Example 2 is 5.5, the average number of layers of the Al2O3-loaded few-layer molybdenum sulfide prepared in Example 3 is 1.4, and the average number of layers of the SiO2-loaded few-layer molybdenum sulfide prepared in Example 2 is 2.4; the materials treated with CH4 / H2S / H2 atmosphere have even fewer molybdenum sulfide layers.

[0059] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a few-layer molybdenum sulfide, characterized in that: The following steps are involved: MoO3 is in-situ sulfided in a mixed atmosphere of methane, hydrogen sulfide and hydrogen to produce a few-layer molybdenum sulfide.

2. The method for preparing a few-layer molybdenum sulfide according to claim 1, characterized in that: The volume ratio of methane, hydrogen sulfide and hydrogen is 2:1:

7.

3. The method for preparing a few-layer molybdenum sulfide according to claim 1, characterized in that: The temperature of the in-situ vulcanization is 700-850°C.

4. A method for preparing supported few-layer molybdenum sulfide, characterized in that: The following steps are involved: The supported MoO3 is in-situ sulfided in a mixed atmosphere of methane, hydrogen sulfide and hydrogen to obtain supported few-layer molybdenum sulfide.

5. The method for preparing supported few-layer molybdenum sulfide according to claim 4, characterized in that: The volume ratio of methane, hydrogen sulfide and hydrogen is 2:1:

7.

6. The method for preparing supported few-layer molybdenum sulfide according to claim 4, characterized in that: The temperature of the in-situ vulcanization is not less than 700°C.

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