Two-dimensional transition metal / alloy sulfides and methods of making the same

Abstract

The present application relates to the technical field of two-dimensional sulfide, in particular to a kind of two-dimensional transition metal / alloy sulfide and preparation method thereof, the method is first mixed with transition metal oxyacid salt and sulfur element-containing salt according to certain mole ratio, then mixed salt is heated at high temperature by tubular furnace, make mixed salt react to generate two-dimensional transition metal / alloy sulfide, and two-dimensional transition metal / alloy sulfide is deposited on growth substrate to obtain single layer / multi-layer two-dimensional transition metal / alloy sulfide, the method for preparing single layer / multi-layer two-dimensional transition metal / alloy sulfide of the present application has the characteristics of simple operation, economy and strong universality.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional sulfide technology, specifically to a class of two-dimensional transition metal / alloy sulfides and their preparation methods. Background Technology

[0002] In the past decade, two-dimensional transition metal sulfides (2D TMS) have attracted widespread attention and research due to their novel properties arising from their unique layered structure and their excellent performance in various applications. However, the quantity of pure-phase 2D TMS with a fixed stoichiometry is limited, and their structure and properties are fixed, making it difficult to meet the diverse requirements of practical applications. Alloying 2D TMS to obtain two-dimensional transition alloy sulfides (2D TAS) allows for multi-faceted control of the physical and chemical properties of 2D TMS, thereby meeting diverse needs. Chemical vapor deposition (CVD) is a widely used method for synthesizing 2D TMS / 2D TAS and is currently one of the most promising technologies suitable for large-scale industrial production of 2D TMS / 2D TAS. Currently, although various CVD methods have been developed to prepare 2D TMS / 2D TAS, such as traditional CVD methods (using sulfur (S) powder to sulfide transition metal oxides at high temperatures), halide-assisted CVD, and molten salt-assisted CVD, these methods all have their own shortcomings: traditional CVD methods are complex to operate and produce low-quality samples; halide-assisted CVD methods struggle to achieve uniform evaporation of the metal precursor, resulting in difficulty in controlling sample thickness and generating many byproducts during synthesis; the main problem with molten salt-assisted CVD is the uncontrollable sample thickness and size caused by the non-uniform evaporation of sulfur, all of which are detrimental to the preparation of high-quality samples. Therefore, developing a novel CVD technology that is simple to operate, time-saving, labor-saving, economical, and widely applicable for the synthesis of 2D TMS / 2D TAS is of great value for promoting the research and application of 2D TMS / 2D TAS. Summary of the Invention

[0003] The purpose of this invention is to solve the problem of how to develop a novel CVD technology that is easy to operate, time-saving, labor-saving, economical and widely applicable for synthesizing various 2D TMS / 2D TAS, and to provide a novel preparation method for a class of two-dimensional transition metal / alloy sulfides.

[0004] To achieve the above objectives, this invention discloses a method for preparing two-dimensional transition metal / alloy sulfides, comprising the following steps:

[0005] S1, after mixing the transition metal oxoate and the sulfur-containing element salt, put them into an open container, place the growth substrate on top of the container, and then place the container in a tube furnace;

[0006] S2, an inert gas is introduced into a tube furnace, and the mixed salt obtained in step S1 is heated. Once the growth temperature is reached, the temperature is maintained until the growth of a single layer or multiple layers of two-dimensional transition metal / alloy sulfides is completed.

[0007] In step S1, the transition metal oxoate salt is any one of Na2MoO4·2H2O, K2MoO4, Na2WO4·2H2O, or NaReO4, which is used to synthesize a single metal sulfide. The sulfur-containing salt is Na2S, K2S, or Na2S·9H2O.

[0008] In step S1, the molar ratio of transition metal oxophosphates and sulfur-containing elemental salts is 1:9.

[0009] The growth temperature in step S2 is 760℃ or 860℃.

[0010] In step S1, when the transition metal oxoate is a mixture of Na2MoO4·2H2O / Na2WO4·2H2O or a mixture of Na2MoO4·2H2O / NaReO4, it is used to synthesize alloy sulfides, and the sulfur-containing salt is Na2S, K2S or Na2S·9H2O.

[0011] The molar ratio of the transition metal oxoacid salt and the sulfur-containing element salt is 1:19.

[0012] The growth temperature in step S2 is 950℃.

[0013] In step S1, the open container is a quartz boat or a ceramic boat, and the growth substrate is alumina or a silicon wafer with a silicon oxide layer on its surface.

[0014] In step S2, the inert gas is nitrogen or argon, and the heating rate is 20°C / minute.

[0015] The present invention also discloses a class of two-dimensional transition metal / alloy sulfides prepared by the above preparation method.

[0016] Compared with existing technologies, the advantages of this invention are as follows: The method for preparing single-layer / multi-layer two-dimensional transition metal / alloy sulfides (2D TMS / 2D TAS) has the characteristics of highly controllable layer number, simple operation, economy, and strong universality. By replacing the sulfur powder used in traditional CVD methods (high-temperature sulfidation of transition metal oxides) with sulfur-containing elemental salts, the problem of difficult quality control of sulfur evaporation can be effectively solved. Mixing transition metal oxometalates and sulfur-containing elemental salts in a molar ratio and grinding them evenly makes the distribution of sulfur precursors in the raw materials more uniform, thereby obtaining high-quality 2D TMS / 2D TAS in subsequent growth. The entire growth process only requires temperature control in a single temperature zone, achieving the goal of simplifying operation and improving production efficiency.

[0017] This invention uses only 2-4 mg of raw materials per batch, compared to 30-40 mg of sulfur powder required in traditional CVD technology, reducing raw material consumption by more than 10 times. Furthermore, this technology avoids the harmful SO2 generation problem encountered in traditional CVD technology during sulfide preparation, making it more environmentally friendly. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the growth furnace structure used in this invention;

[0019] Figure 2 This is a characterization of the monolayer MoS2 in Embodiment 1 of the present invention. Figure 2 a is an optical microscope image of a single layer of MoS2 in the example. Figure 2 b is the Raman spectrum of monolayer MoS2 in the example. Figure 2 c shows the photoluminescence spectrum of monolayer MoS2 in the embodiment;

[0020] Figure 3 This is a characterization of the single-layer WS2 in Embodiment 10 of the present invention. Figure 3 a is an optical microscope image of a single layer of WS2 in the embodiment. Figure 3 b is the Raman spectrum of a single layer of WS2 in the embodiment. Figure 3 c represents the photoluminescence spectrum of a single-layer WS2 in the embodiment;

[0021] Figure 4 This is a characterization of the few-layer ReS2 in Embodiment 12 of the present invention. Figure 4 a is an optical microscope image of the few-layer ReS2 sample from the example. Figure 4 b is the Raman spectrum of the few-layer ReS2 sample in the example. Figure 4 c is the photoluminescence spectrum of the few-layer ReS2 sample in the example;

[0022] Figure 5 Mo in Embodiment 14 of the present invention x W 1-xCharacterization of S2 (0 < x < 1) alloy, Figure 5 a is the sample Mo from the example. x W 1-x Optical microscope images of S2 alloy. Figure 5 b is the sample Mo from the example. x W 1-x Raman spectrum of S2 alloy Figure 5 c represents the sample Mo from the example. x W 1-x Photoluminescence spectrum of S2 alloy;

[0023] Figure 6 Mo in Embodiment 15 of the present invention x Re 1-x Characterization of S2 (0 < x < 1) alloy, Figure 6 a is the sample Mo from the example. x Re 1-x Optical microscope images of S2 alloy. Figure 6 b is the sample Mo from the example. x Re 1-x Raman spectrum of S2 alloy Figure 6 c represents the sample Mo from the example. x Re 1-x Photoluminescence spectrum of S2 alloy;

[0024] Figure 7 This describes the characterization of sulfides obtained from mixed salts of transition metal oxoates and sulfur-containing elemental salts with different molar ratios as precursors in Examples 1, 5, and 6 of this invention. Figure 7 Image a, c, are optical microscope images of MoS2 obtained using mixed salt powders of sulfur-containing elemental salt Na2S and transition metal oxoate Na2MoO4·2H2O in molar ratios of 3:1, 9:1, and 19:1 as precursors. Figure 7 df are statistical graphs showing the distribution of different number of layers of MoS2 obtained by using Na2S / Na2MoO4·2H2O mixed salt powder with molar ratios of 3:1, 9:1 and 19:1 as precursors. Figure 7 The illustration in f shows the proportion of monolayer sample yield as a function of the molar ratio of transition metal oxoates and sulfur-containing elemental salts.

[0025] Figure 8 These are optical microscope images of sulfides obtained at different growth temperatures in Examples 1, 7-9, and 12-13 of this invention. Figure 8 a and Figure 8 b are optical microscope images of MoS2 grown at 600℃ and 860℃, respectively. Figure 8 c and Figure 8 Image d shows optical microscope images of WS2 grown at 860℃ and 900℃, respectively. Figure 8 e and Figure 8 f are optical microscope images of ReS2 grown at 760℃ and 820℃, respectively.

[0026] The numbers in the diagram represent:

[0027] 1-Heater; 2-Open container; 3-Growth substrate; 4-Growth furnace cavity. Detailed Implementation

[0028] The above and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0029] The present invention provides a method for preparing monolayer / few-layer 2D TMS / 2D TAS using mixed salts as precursors, which mainly includes two steps: the first step is to mix transition metal oxophosphates and sulfur-containing element salts in a certain molar ratio, and the second step is to heat the mixed salts in a tube furnace to synthesize monolayer / multilayer 2D TMS / 2D TAS.

[0030] Transition metal oxoates and sulfur-containing salts are mixed in a certain molar ratio. Specifically, a certain amount of sulfur-containing salt powder is weighed, and the mass of transition metal oxoate powder to be weighed is calculated according to the molar ratio. After weighing, the powder is poured into a mortar and mixed with the sulfur-containing salt powder. The mixture is then thoroughly ground with a pestle to ensure that the two are evenly mixed.

[0031] The synthesis of 2D TMS / 2D TAS includes the following steps:

[0032] S11: After mixing transition metal oxophosphate powder and sulfur-containing element salt powder in a certain molar ratio, put them into an open container, place a growth substrate on top of the container, and then place the container in a tube furnace.

[0033] S12: Inert gas at a certain flow rate is passed through a tube furnace to heat the mixed salt powder; when the growth temperature is reached, the temperature is maintained for a certain time to grow a single layer / few layers of 2D TMS / 2D TAS on the growth substrate.

[0034] Figure 1 This is a schematic diagram of the tube furnace structure used in the above steps. In the diagram, 1 is the heater, 2 is the open container, 3 is the growth substrate, and 4 is the growth furnace cavity.

[0035] In the above-described 2D TMS / 2D TAS synthesis steps, the transition metal oxoate can be a sodium salt containing the target transition metal element, a potassium salt containing the target transition metal element, or other salts containing the target transition metal element; the sulfur-containing salt can be a sulfur-containing sodium salt, a sulfur-containing potassium salt, or other sulfur-containing salts. By selecting suitable transition metal oxoates and sulfur-containing salts, this invention can prepare most types of 2D TMS / 2D TAS.

[0036] Example 1

[0037] A quartz boat was filled with 4 mg of a Na₂S / K₂MoO₄ mixed salt at a molar ratio of 9:1, and the SiO₂ / Si growth substrate was placed directly above the mixture. The quartz boat was placed in a tube furnace, nitrogen gas was introduced, and the mixture was heated to 860°C at a heating rate of 20°C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the nitrogen gas was turned off to complete the growth of MoS₂. The nitrogen gas flow rate was maintained at 150 cubic centimeters per minute (SCCM) throughout the heating, holding, and cooling processes.

[0038] Example 2

[0039] 4 mg of a Na₂S / Na₂MoO₄·2H₂O mixed salt with a molar ratio of 9:1 was placed in a quartz boat. The mixture was heated to 860°C at a heating rate of 20°C / min and held at this temperature for 10 minutes. After the reaction was complete, the system was allowed to cool naturally to room temperature, and the nitrogen gas was turned off to complete the growth of MoS₂. The nitrogen gas flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0040] Example 3

[0041] 3 mg of a K₂S / K₂MoO₄ mixed salt with a molar ratio of 9:1 was placed in a quartz boat, and the growth substrate SiO₂ / Si was placed directly above the mixture. The quartz boat was placed in a tube furnace, nitrogen gas was introduced, and the mixture was heated to 860°C at a heating rate of 20°C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the nitrogen gas was turned off to complete the growth of MoS₂. The nitrogen gas flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0042] Example 4

[0043] 4 mg of a K₂S / Na₂MoO₄·2H₂O mixed salt with a molar ratio of 9:1 was placed in a quartz boat, and the growth substrate SiO₂ / Si was placed directly above the mixture. The quartz boat was placed in a tube furnace, nitrogen gas was introduced, and the mixture was heated to 860°C at a heating rate of 20°C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the nitrogen gas was turned off to complete the growth of MoS₂. The nitrogen gas flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0044] Example 5

[0045] A 3 mg Na₂S / K₂MoO₄ mixed salt solution with a molar ratio of 3:1 was placed in a quartz boat, and the SiO₂ / Si growth substrate was placed directly above the mixed salt solution. The mixed salt solution was heated to 860 °C at a heating rate of 20 °C / min and held at that temperature for 10 minutes. After the reaction was complete, the system was allowed to cool naturally to room temperature and the gas supply was shut off to complete the growth of MoS₂. The nitrogen flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0046] Example 6

[0047] A 3 mg Na₂S / K₂MoO₄ mixed salt solution with a molar ratio of 19:1 was placed in a quartz boat, and the SiO₂ / Si growth substrate was placed directly above the mixed salt solution. The mixed salt solution was heated to 860 °C at a heating rate of 20 °C / min and held at that temperature for 10 minutes. After the reaction was complete, the system was allowed to cool naturally to room temperature and the gas supply was shut off to complete the growth of MoS₂. The nitrogen flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0048] Example 7

[0049] 2 mg of a K₂S / K₂MoO₄ mixed salt with a molar ratio of 19:1 was placed in a quartz boat, and the SiO₂ / Si growth substrate was placed directly above the mixed salt. The mixed salt was heated to 600 °C at a heating rate of 20 °C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the gas was turned off to complete the growth of MoS₂. The nitrogen flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0050] Example 8

[0051] A 6 mg mixture of Na₂S·9H₂O / Na₂WO₄·2H₂O (9:1 molar ratio) was placed in a quartz boat, with the SiO₂ / Si growth substrate positioned directly above it. The mixture was heated to 860 °C at a rate of 20 °C / min and held at that temperature for 10 minutes. After the reaction was complete, the system was allowed to cool naturally to room temperature, and the gas supply was shut off to complete the growth of WS₂. Throughout the heating, holding, and cooling processes, the flow rate of the nitrogen / hydrogen mixture was maintained at 302 SCCM, with nitrogen at 300 SCCM and hydrogen at 2 SCCM.

[0052] Example 9

[0053] 5 mg of a Na₂S·9H₂O / Na₂WO₄·2H₂O mixed salt with a molar ratio of 9:1 was placed in a quartz boat, and the growth substrate SiO₂ / Si was placed directly above the mixed salt. The mixed salt was heated to 900°C at a heating rate of 20°C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the gas supply was turned off to complete the growth of WS₂. Throughout the heating, holding, and cooling processes, the flow rate of the nitrogen / hydrogen mixed gas was maintained at 302 SCCM, with nitrogen at a flow rate of 300 SCCM and hydrogen at a flow rate of 2 SCCM.

[0054] Example 10

[0055] 4 mg of a Na₂S·9H₂O / Na₂WO₄·2H₂O mixed salt with a molar ratio of 9:1 was placed in a quartz boat, and the growth substrate SiO₂ / Si was placed directly above the mixture. The quartz boat was placed in a tube furnace, nitrogen gas was introduced, and the mixture was heated to 860°C at a heating rate of 20°C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the nitrogen gas was turned off to complete the growth of WS₂. The nitrogen gas flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0056] Example 11

[0057] 3 mg of a K₂S / Na₂WO₄·2H₂O mixed salt with a molar ratio of 9:1 was placed in a quartz boat, and the growth substrate SiO₂ / Si was placed directly above the mixture. The quartz boat was placed in a tube furnace, nitrogen gas was introduced, and the mixture was heated to 860°C at a heating rate of 20°C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the nitrogen gas was turned off to complete the growth of WS₂. The nitrogen gas flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0058] Example 12

[0059] A quartz boat was filled with 4 mg of a Na₂S / NaReO₄ mixed salt at a molar ratio of 9:1, and the SiO₂ / Si growth substrate was placed directly above the mixture. The quartz boat was placed in a tube furnace, nitrogen gas was introduced, and the mixture was heated to 760°C at a heating rate of 20°C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the nitrogen gas was turned off, thus completing the growth of ReS₂. The nitrogen gas flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0060] Example 13

[0061] A 2 mg Na₂S / NaReO₄ mixed salt solution with a molar ratio of 14:1 was placed in a quartz boat, and the SiO₂ / Si growth substrate was placed directly above the mixed salt solution. The mixed salt solution was heated to 900 °C at a heating rate of 20 °C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the gas supply was turned off to complete the growth of ReS₂. The nitrogen flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0062] Example 14

[0063] 3 mg of a K₂S / Na₂MoO₄·2H₂O / Na₂WO₄·2H₂O mixed salt with a molar ratio of 95:2:3 was placed in a quartz boat, and the SiO₂ / Si growth substrate was placed directly above the mixed salt. The mixed salt powder was heated to 950 °C at a heating rate of 20 °C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the gas was turned off to complete the Mo₂O₃ reaction. x W 1-x Growth of S2 alloy. Nitrogen flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0064] Example 15

[0065] 3 mg of a K₂S / Na₂MoO₄·2H₂O / NaReO₄ mixed salt with a molar ratio of 95:2:3 was placed in a quartz boat, and the SiO₂ / Si growth substrate was placed directly above the mixed salt. The mixed salt was heated to 950 °C at a heating rate of 20 °C / min and held at that temperature for 10 minutes. After the reaction was completed, the system was allowed to cool naturally to room temperature and the gas was turned off to complete the Mo₂O₃ reaction. x Re 1-x Growth of S2 alloy. Nitrogen flow rate was maintained at 150 SCCM throughout the heating, holding, and cooling processes.

[0066] Figure 2 This is a characterization of the monolayer MoS2 in Embodiment 1 of the present invention. Wherein, Figure 2 Image a is an optical microscope image of the monolayer MoS2 sample from Example 1, showing a typical triangular morphology of the monolayer MoS2 sample. Figure 2 b and 2c are the Raman spectrum and photoluminescence spectrum of monolayer MoS2 sample from Example 1, respectively.

[0067] Figure 3 This is a characterization of the single-layer WS2 in Embodiment 10 of the present invention. Wherein, Figure 3 Image a shows an optical microscope image of a monolayer WS2 sample from the example, illustrating a typical triangular morphology of the grown monolayer WS2 sample. Figure 3 b and 3c are the Raman spectrum and photoluminescence spectrum of the monolayer WS2 sample in the example, respectively.

[0068] Figure 4 This is a characterization of the few-layer ReS2 in Embodiment 12 of the present invention. Wherein, Figure 4 Image a is an optical microscope image of ReS2 from the example sample, showing the typical morphology of the grown ReS2 sample, where the edges are a single-layer structure and the center is a multi-layer structure. Figure 4 b and 4c are the Raman spectrum and photoluminescence spectrum of the ReS2 sample in the example, respectively.

[0069] Figure 5 Mo in Embodiment 14 of the present invention x W 1-x Characterization of S2 alloy. Among them, Figure 5 a is the sample Mo from the example. x W 1-x Optical microscope images of S2 alloy show a typical morphology of the grown sample. Figure 5 b and Figure 5 c represents the Mo sample from the example. x W 1-x Raman and photoluminescence spectra of S2 alloy.

[0070] Figure 6 Mo in Embodiment 15 of the present invention x Re 1-x Characterization of S2 alloy. Among them, Figure 6 a is the sample Mo from the example. x Re 1- x Optical microscope images of S2 alloy show a typical morphology of the grown sample. Figure 6 b and Figure 6 c represents the Mo sample from the example. x Re 1-x Raman and photoluminescence spectra of S2 alloy.

[0071] Figure 7 Characterization of sulfides obtained by using a mixture of transition metal oxoates and sulfur-containing element salts in different molar ratios as precursors in Examples 1, 5, and 6 of this invention. Figure 7 Image a, c, are optical microscope images of MoS2 obtained using mixed salt powders of sulfur-containing elemental salt Na2S and transition metal oxoate Na2MoO4·2H2O in molar ratios of 3:1, 9:1, and 19:1 as precursors. Figure 7 df are statistical graphs showing the distribution of different number of layers in MoS2 obtained by using Na2S / Na2MoO4·2H2O mixed salt powder with molar ratios of 3:1, 9:1 and 19:1 as precursors. Figure 7The inset in f shows the change in the proportion of monolayer samples with the molar ratio of transition metal oxoates and sulfur-containing elemental salts. As can be seen from the figure, as the content of Na2MoO4·2H2O decreases, the monolayer yield can increase from 5% to nearly 90%, indicating that the technology has good control over the number of layers of the obtained sulfide.

[0072] Figure 8 These are optical microscope images of sulfides obtained at different growth temperatures in Examples 1, 7-9 and 12-13 of the present invention. Figure 8 a and Figure 8 b are optical microscope images of MoS2 grown at 600℃ and 860℃, respectively. Figure 8 c and Figure 8 Image d shows optical microscope images of WS2 grown at 860℃ and 900℃, respectively. Figure 8 e and Figure 8 Images f are optical microscope images of ReS2 grown at 760℃ and 820℃, respectively. The figures show a close relationship between sample quality and growth temperature, indicating that this technique allows for the control of sample quality by adjusting the temperature.

[0073] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing a class of two-dimensional transition metal / alloy sulfides, characterized in that, Includes the following steps: S1, after mixing the transition metal oxoate and the sulfur-containing element salt, put them into an open container, place the growth substrate on top of the container, and then place the container in a tube furnace; S2, Inert gas is introduced into the tube furnace and the mixed salt obtained in step S1 is heated. When the growth temperature is reached, the temperature is maintained until the growth of a single layer or multiple layers of two-dimensional transition metal / alloy sulfide is completed. In step S1, the transition metal oxophosphate is any one of Na2MoO4·2H2O, K2MoO4, Na2WO4·2H2O, and NaReO4, and the sulfur-containing salt is Na2S, K2S, or Na2S·9H2O.

2. The method for preparing a type of two-dimensional transition metal / alloy sulfide as described in claim 1, characterized in that, The molar ratio of the transition metal oxoacid salt and the sulfur-containing element salt is 1:

9.

3. The method for preparing a type of two-dimensional transition metal / alloy sulfide as described in claim 1, characterized in that, The growth temperature in step S2 is 760℃ or 860℃.

4. The method for preparing a type of two-dimensional transition metal / alloy sulfide as described in claim 1, characterized in that, In step S1, the transition metal oxoate is a mixture of Na2MoO4·2H2O / Na2WO4·2H2O or a mixture of Na2MoO4·2H2O / NaReO4, and the sulfur-containing salt is Na2S, K2S or Na2S·9H2O.

5. The method for preparing a type of two-dimensional transition metal / alloy sulfide as described in claim 4, characterized in that, The molar ratio of the transition metal oxoacid salt and the sulfur-containing element salt is 1:

19.

6. The method for preparing a type of two-dimensional transition metal / alloy sulfide as described in claim 4, characterized in that, The growth temperature in step S2 is 950℃.

7. The method for preparing a type of two-dimensional transition metal / alloy sulfide as described in claim 1, characterized in that, In step S1, the open container is a quartz boat or a ceramic boat, and the growth substrate is alumina or a silicon wafer with a silicon oxide layer on its surface.

8. The method for preparing a type of two-dimensional transition metal / alloy sulfide as described in claim 1, characterized in that, In step S2, the inert gas is nitrogen or argon, and the heating rate is 20°C / minute.

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