Sulfur vacancy CdS / sulfur vacancy 1T-MoS2 composite photocatalytic material as well as preparation method and application thereof

Abstract

The invention discloses a sulfur vacancy CdS and sulfur vacancy 1T-MoS2 composite photocatalytic material as well as a preparation method and application thereof, and belongs to the technical field of photoelectric energy materials. Sulfur vacancy CdS is grown on the surface of sulfur vacancy 1T-MoS2 in situ, and the sulfur vacancy CdS and sulfur vacancy 1T-MoS2 composite photocatalytic material is constructed. The preparation method comprises the following steps: preparing the sulfur vacancy 1T-MoS2 nanosheet, and preparing the sulfur vacancy CdS and sulfur vacancy 1T-MoS2 composite photocatalytic material. According to the composite photocatalytic material, the catalyst shows excellent photocatalytic nitrogen fixation activity under the irradiation of a xenon lamp, and the generation rate of ammonia reaches 15730.25 [mu] moL <-1 > g <-1 > h <-1 >. The photocatalyst prepared by the invention has the advantages of simple preparation process, high catalytic efficiency and the like, and has a very wide application prospect in the technical field of photocatalysis such as photocatalytic nitrogen fixation.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic energy materials technology, specifically a sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material, its preparation method and application. Background Technology

[0002] Solar energy, as a new energy source, has advantages such as being clean, pollution-free, and renewable. Nitrogen (N2) constitutes up to 78% of the atmosphere and is an essential element for almost all life forms on Earth. Nitrogen and its compounds have wide applications in daily life and production. Ammonia (NH3) is an important chemical product, widely used in fertilizers, plastics, pharmaceuticals, and other fields, and is crucial to global food production, also showing great potential in the field of clean energy. However, due to the stable and inert nature of nitrogen molecules, converting N2 to NH3 under mild conditions remains a significant challenge. Traditional ammonia synthesis processes (Haber-Bosch process) require high-temperature (350-550 ℃) and high-pressure (150-350 atm) reaction conditions, resulting in high energy consumption and high pollution. Therefore, seeking efficient, low-energy, and clean nitrogen fixation methods for ammonia synthesis has become a research hotspot in recent years.

[0003] Inspired by natural photosynthesis, the conversion of N2 and water into NH3 using solar energy through photocatalysis has attracted considerable attention. Photocatalytic nitrogen fixation technology, due to its mild reaction conditions, has become a highly promising alternative. Subsequently, numerous efforts have been made to improve the performance of photocatalytic nitrogen fixation, and many semiconductor catalysts have been synthesized. However, due to poor visible light trapping ability and high recombination rate of photogenerated carriers, the photocatalytic nitrogen fixation activity of most semiconductor catalysts is very low. Therefore, there is an urgent need to develop a superior photocatalyst to improve the efficiency of photocatalytic nitrogen fixation.

[0004] Cadmium sulfide (CdS) has attracted much attention due to its suitable bandgap and excellent photoelectric properties. As a visible-light-responsive semiconductor material, CdS possesses a unique electronic structure and tunable optical properties. Its bandgap of approximately 2.4 eV enables it to effectively absorb visible light, making it widely used in photocatalytic water splitting for hydrogen production and degradation of organic pollutants. However, CdS suffers from high photogenerated electron-hole pair recombination efficiency and photocorrosion. Sulfur vacancy engineering can enhance the visible-light response and photogenerated carrier separation efficiency of CdS, representing an effective strategy to improve its photocatalytic performance. Furthermore, CdS's light absorption is mainly concentrated in the visible light region, while near-infrared light accounts for approximately 43% of sunlight. Its low utilization efficiency of near-infrared light limits the efficient conversion of solar energy. Therefore, using co-catalysts to broaden the light absorption range of CdS and achieve more efficient utilization of the broader solar spectrum is an effective strategy to improve its photocatalytic performance.

[0005] Catalyst modification is an effective method to improve the catalytic performance and stability of CdS. Among them, 1T-MoS2 (1T-MoS2) has become a research hotspot due to its rich physicochemical properties. Exhibiting a triangular crystal structure, it possesses metallic electronic structure and conductivity, effectively promoting electron transport and making it an ideal cocatalyst. Furthermore, sulfur vacancies, as structural defects in 1T-MoS2, not only provide abundant adsorption, activation, and reactive sites but also exhibit good conductivity and stability. In photocatalytic nitrogen fixation, N2 adsorption and activation are crucial, and regulating their capabilities can effectively enhance photocatalytic activity; sulfur-vacancy 1T-MoS2 perfectly meets this requirement. In addition, sulfur-vacancy 1T-MoS2 can broaden the light absorption range of CdS, allowing for more efficient utilization of sunlight. Therefore, utilizing sulfur-vacancy 1T-MoS2 as a cocatalyst to improve the photocatalytic nitrogen fixation performance of sulfur-vacancy CdS is of great significance for achieving efficient, broad-spectrum photocatalytic nitrogen fixation under sunlight. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, the present invention aims to provide a sulfur-vacancy CdS@sulfur-vacancy 1T-MoS2 composite photocatalyst, its preparation method, and its applications. This photocatalytic method enables the reduction of nitrogen to ammonia at room temperature and pressure. In this composite catalyst, a co-catalyst strategy is employed, with sulfur-vacancy CdS grown in situ on sulfur-vacancy 1T-MoS2 as a co-catalyst. Experimental studies have shown that the photocatalytic nitrogen fixation performance of the sulfur-vacancy CdS@sulfur-vacancy 1T-MoS2 composite photocatalyst is significantly improved compared to that of sulfur-vacancy CdS alone. The catalyst overcomes the problems of low reduction capacity of photogenerated electrons and high recombination rate of photogenerated carriers, while effectively utilizing the unique active sites and efficient N2 adsorption and activation effects of the sulfur-vacancy 1T-MoS2 co-catalyst.

[0007] The sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material is characterized by comprising sulfur vacancy 1T-MoS2 nanosheets and sulfur vacancy CdS grown in situ on the surface of the sulfur vacancy 1T-MoS2 nanosheets.

[0008] The method for preparing a sulfur-vacancy CdS@sulfur-vacancy 1T-MoS2 composite photocatalytic material is characterized by comprising the following steps: 1) Dissolve ammonium molybdate tetrahydrate and thiourea in deionized water at a mass ratio of 1:0.5-2. The concentration of ammonium molybdate tetrahydrate is 10-20 mg / mL. Stir at room temperature and carry out hydrothermal reaction treatment. Centrifuge the obtained precipitate, wash it, and vacuum dry it overnight to obtain black sulfur vacancy 1T-MoS2 powder. 2) Disperse the 1T-MoS2 powder obtained in step 1) in deionized water / anhydrous ethanol / ethylenediamine, with a volume ratio of deionized water:anhydrous ethanol:ethylenediamine of 1:0.5-1.5:3-5, and a concentration of 1T-MoS2 powder of 0.15-0.5 mg / mL. Disperse the powder evenly by ultrasonication to obtain a mixed solution. 3) Then, cadmium acetate dihydrate and thiourea in a mass ratio of 1:2-5 were dissolved in the above mixed solution. The concentration of cadmium acetate dihydrate was 6-12 mg / mL. The mixture was stirred vigorously at room temperature until homogeneous. Finally, the resulting mixed solution was subjected to hydrothermal reaction treatment. The precipitate was centrifuged, washed, and vacuum dried overnight to obtain a dark green sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material. The mass ratio of sulfur vacancy 1T-MoS2 to sulfur vacancy CdS was 1:10-40.

[0009] The method for preparing a sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material is characterized in that, in step 1), the mass ratio of ammonium molybdate tetrahydrate to thiourea is 1:1-1.5, the concentration of ammonium molybdate tetrahydrate is 14-16 mg / mL, the hydrothermal reaction temperature is 160-200 ℃, the hydrothermal reaction time is 10-16 h, and the overnight vacuum drying temperature is 50-80 ℃.

[0010] The method for preparing a sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material is characterized in that, in step 2), the volume ratio of deionized water: anhydrous ethanol: ethylenediamine is 1:0.8-1.2:3.5-4, and the concentration of 1T-MoS2 powder is 0.2-0.3 mg / mL.

[0011] The method for preparing a sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material is characterized in that, in step 3), the mass ratio of cadmium acetate dihydrate to thiourea is 1:3-4, and the concentration of cadmium acetate dihydrate is 8-10 mg / mL.

[0012] The method for preparing a sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material is characterized in that, in step 3), the hydrothermal reaction conditions are: hydrothermal reaction temperature is 80-160 ℃; hydrothermal reaction time is 12-36 h; vacuum drying overnight temperature is 50-80 ℃; and the mass ratio of sulfur vacancy 1T-MoS2 to sulfur vacancy CdS is 1:20-30.

[0013] The application of the sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material in photocatalytic nitrogen fixation reaction.

[0014] The application is characterized in that, at room temperature and pressure, the composite material is used as a catalyst to reduce N2 to NH3 under light irradiation.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The preparation method of this high-performance photocatalytic nitrogen fixation catalyst, sulfur vacancy CdS, is simple and efficient, and can fundamentally realize the ammonia synthesis by nitrogen reduction at room temperature and pressure through photocatalysis. It effectively overcomes the problems of low photocatalytic reduction efficiency of CdS for N2, weak photogenerated electron reduction ability, and high recombination rate of photogenerated carriers.

[0016] 2. The preparation method of this high-performance photocatalytic nitrogen fixation catalyst, sulfur-vacancy CdS@sulfur-vacancy 1T-MoS2 composite photocatalyst, is convenient and rapid. The composite photocatalyst possesses advantages such as broad spectral response and high photocatalytic efficiency, making it a promising photocatalytic nitrogen fixation catalyst. Modification by introducing sulfur-vacancy 1T-MoS2 co-catalyst enhances N2 adsorption and activation, accelerates electron transport, and overcomes the shortcomings of weak N2 adsorption and activation capacity and low reduction capacity of photogenerated electrons in sulfur-vacancy CdS materials. Furthermore, sulfur-vacancy 1T-MoS2 can broaden the light absorption range of CdS, enabling more efficient utilization of sunlight.

[0017] 3. This invention tested the effects of reagent ratios and solvent composition on the composite material's performance in the photocatalytic ammonia fixation reaction, and determined the optimal synthesis parameters. The performance of sulfur-vacancy CdS is 2.09 times that of CdS; the performance of the sulfur-vacancy CdS@sulfur-vacancy 1T-MoS2 composite photocatalyst is 3.02 times that of CdS and 1.44 times that of sulfur-vacancy CdS. The preparation method of this high-performance photocatalytic nitrogen fixation catalyst is simple and shows promise for industrial application. Attached Figure Description

[0018] Figure 1 XRD patterns of the prepared samples: (a) sulfur vacancy 1T-MoS2, (b) CdS, (c) sulfur vacancy CdS, (d) sulfur vacancy CdS@sulfur vacancy 1T-MoS2; Figure 2 SEM images of the prepared samples: (a, b) sulfur vacancy 1T-MoS2, (c, d) CdS, (e, f) sulfur vacancy CdS, (g, h) sulfur vacancy CdS@sulfur vacancy 1T-MoS2; Figure 3 SEM-EDX image of sulfur vacancy CdS@sulfur vacancy 1T-MoS2 in the prepared sample; Figure 4 (A) UV-Vis DRS spectrum and (B) band gap width plot of the prepared sample (a) CdS, (b) sulfur vacancy CdS, (c) sulfur vacancy CdS@sulfur vacancy 1T-MoS2; Figure 5(A) Photoluminescence spectrum and (B) Fluorescence lifetime decay spectrum of the prepared samples (a) CdS, (b) sulfur vacancy CdS, (c) sulfur vacancy CdS@sulfur vacancy 1T-MoS2; Figure 6 EPR spectra of the prepared samples under (A) magnetic field and (B) g value range: (a) CdS, (b) sulfur vacancy CdS, (c) sulfur vacancy 1T-MoS2, (d) sulfur vacancy CdS@sulfur vacancy 1T-MoS2. Figure 7 (A) EIS Nyquist plot and (B) transient photocurrent response plot of the prepared sample (a) CdS, (b) sulfur vacancy CdS, (c) sulfur vacancy CdS@sulfur vacancy 1T-MoS2; Figure 8 To prepare the sample of (A)NH4 + Generation time curve and (B)NH4 + Generation rate diagrams: (a) CdS, (b) CdS with sulfur vacancies, (c) CdS with sulfur vacancies@1T-MoS2. Detailed Implementation

[0019] The technical solutions of the present invention will be described in detail below with reference to the embodiments and accompanying drawings. Of course, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by researchers in the art without creative effort are within the scope of protection of the present invention.

[0020] The materials and reagents used in the following examples and comparative examples include: ammonium molybdate tetrahydrate, thiourea, cadmium acetate dihydrate, ethylenediamine, anhydrous methanol, and anhydrous ethanol, all purchased from Sinopharm Chemical Reagent Co., Ltd. All chemicals are ready for use without further purification.

[0021] The present invention discloses a sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material, comprising sulfur vacancy 1T-MoS2 nanosheets and sulfur vacancy CdS grown in situ on the surface of the sulfur vacancy 1T-MoS2 nanosheets.

[0022] Examples of the preparation method of the composite photocatalytic material of the present invention are as follows: Example 1

[0023] 1) Preparation of sulfur vacancy 1T-MoS2: 1.16 g of ammonium molybdate tetrahydrate and 1.06 g of thiourea were dissolved in 70 mL of deionized water and stirred at room temperature for 30 min; then the resulting mixed solution was subjected to hydrothermal reaction at 180 ℃ for 12 h; finally, the precipitate was centrifuged, washed three times, and vacuum dried overnight at 60 ℃ to obtain black sulfur vacancy 1T-MoS2 powder.

[0024] 2) Preparation of sulfur vacancy CdS@sulfur vacancy 1T-MoS2: 7.5 mg of sulfur vacancy 1T-MoS2 powder was dispersed in 30 mL of a mixed solution of deionized water / anhydrous ethanol / ethylenediamine (volume ratio 1:1:4) and ultrasonically dispersed until uniform. 3) Then, 266.53 mg of cadmium acetate dihydrate and 913.44 mg of thiourea were dissolved in the above mixed solution and stirred vigorously at room temperature for 60 min; then, the resulting mixed solution was subjected to hydrothermal reaction at 100 °C for 24 h; finally, the precipitate was centrifuged, washed three times, and vacuum dried overnight at 60 °C to obtain dark green sulfur vacancy CdS@sulfur vacancy 1T-MoS2.

[0025] In step 1) of this invention: the mass ratio of ammonium molybdate tetrahydrate to thiourea is 1:0.5 or 1:2, the concentration of ammonium molybdate tetrahydrate is 10 mg / mL or 20 mg / mL, the hydrothermal reaction temperature is 160 ℃ or 200 ℃, the hydrothermal reaction time is 10 h or 16 h, and the overnight vacuum drying temperature is 50 ℃ or 80 ℃; in step 2): the volume ratio of deionized water: anhydrous ethanol: ethylenediamine is 1:0.5:4.5 or 1:1.5:3.5, and the concentration of 1T-MoS2 powder is 0.15 mg / mL or 0.5 mg / mL; in step 3): the mass ratio of cadmium acetate dihydrate to thiourea is 1:2 or 1:5, the concentration of cadmium acetate dihydrate is 6 mg / mL or 12 mg / mL, the hydrothermal reaction temperature is 80 ℃ or 160 ℃, and the time is 12 h or 36 h; other aspects are the same as in Example 1, and the beneficial effects described in this invention can also be obtained.

[0026] Comparative Example 1: Preparation of CdS: 266.53 mg of cadmium acetate dihydrate and 228.36 mg of thiourea were dissolved in 30 mL of deionized water / ethylenediamine mixed solution (volume ratio 1:5) and stirred at room temperature for 30 min; then the resulting mixed solution was subjected to hydrothermal reaction at 100 °C for 24 h; finally, the precipitate was centrifuged, washed three times, and vacuum dried overnight at 60 °C to obtain bright yellow CdS powder.

[0027] Comparative Example 2: Preparation of sulfur vacancy CdS: 266.53 mg of cadmium acetate dihydrate and 913.44 mg of thiourea were dissolved in 30 mL of a mixed solution of deionized water / anhydrous ethanol / ethylenediamine (volume ratio 1:1:4) and stirred at room temperature for 30 min; then the resulting mixed solution was subjected to hydrothermal reaction at 100 °C for 24 h; finally, the precipitate was centrifuged, washed three times, and vacuum dried overnight at 60 °C to obtain yellow sulfur vacancy CdS powder.

[0028] The following data further demonstrates the beneficial effects of the present invention.

[0029] 1. Photocatalytic Nitrogen Fixation Process: Photocatalytic nitrogen fixation and ammonia synthesis experiments were conducted on a self-assembled photocatalytic reaction platform. Photocatalytic ammonia fixation was achieved at a three-phase interface (gas phase N2, liquid phase H2O, and solid phase photocatalyst) at room temperature and atmospheric pressure. A 300 W xenon lamp (full spectrum) was used as the light source, with the light source 10 cm above the liquid surface. The specific experimental steps are as follows: First, 20 mg of the photocatalyst prepared in Example 1 was dispersed in 100 mL of methanol solution (methanol: 20%, deionized water: 80%) and added to a reactor equipped with a circulating water system. Second, high-purity N2 was introduced into the mixture under light-free conditions, and the mixture was continuously stirred for 30 minutes until the N2 in the aqueous solution reached saturation. Then, light conditions were applied, and 5 mL of the reaction solution was taken every 30 minutes and filtered through a 0.2 μm filter to detect the ammonia content.

[0030] 2. Detection method for ammonium ions in aqueous solution: The Nessler reagent method is used for the analysis and detection of NH4+. + The concentration was determined. Filter 5 mL of the suspension to obtain a clear solution for testing. Add Nessler's reagent and mix thoroughly, then let stand for 10 min. Measure the absorbance at λ = 420 nm using a UV-Vis spectrophotometer. Calculate the NH4 produced during the reaction based on the established standard curve. + The concentration.

[0031] 3. The phase structure of the catalyst was characterized using powder X-ray diffraction (XRD), demonstrating the successful synthesis of sulfur vacancy CdS@sulfur vacancy 1T-MoS2. The XRD pattern of 1T-MoS2 showed the successful preparation of the 1T phase; a comparison of the XRD patterns of CdS and sulfur vacancy CdS showed a decrease in the diffraction peak intensity of sulfur vacancy CdS, indicating the successful construction of sulfur vacancies; and the presence of 1T-MoS2 diffraction peaks in the XRD pattern of sulfur vacancy CdS@sulfur vacancy 1T-MoS2 indicated the successful preparation of the composite material.

[0032] 4. The morphology of the catalyst was characterized using scanning electron microscopy (SEM) to obtain the corresponding catalyst morphology. For example... Figure 2 a and Figure 2 As shown in b, 1T-MoS2 exhibits a flower-like structure, which facilitates N2 adsorption and electron transfer; as Figure 2 c. Figure 2 d、 Figure 2 e and Figure 2 As shown in f, CdS and sulfur-vacant CdS exhibit distinct nanorod structures; as Figure 2 g and Figure 2 As shown in h, sulfur-vacant CdS nanorods were successfully grown in situ on sulfur-vacant 1T-MoS2 nanosheets in the composite material, forming a tight heterojunction interface, indicating the successful preparation of the composite material.

[0033] 5. The elemental distribution of the catalyst was characterized using energy-dispersive X-ray spectroscopy (EDX) of sulfur vacancies CdS@sulfur vacancies 1T-MoS2, yielding the corresponding elemental distribution of the catalyst. For example... Figure 3 As shown in the elemental distribution diagram, Cd, S, and Mo are evenly distributed, further confirming the successful construction of the composite material.

[0034] 6. The catalyst's spectroscopic properties are characterized using UV-Vis diffuse reflectance (DRS) spectroscopy to obtain the corresponding absorption spectrum. For example... Figure 4 A. Spectroscopic results show that the absorption margin of sulfur vacancy CdS@sulfur vacancy 1T-MoS2 is red-shifted compared to CdS; and the calculated band gap indicates that the band gap of sulfur vacancy CdS@sulfur vacancy 1T-MoS2 is narrower.

[0035] 7. The electronic properties of the catalyst are characterized using steady-state and transient photoluminescence (PL) curves. For example... Figure 5 A. The peak intensity of sulfur-vacancy CdS is enhanced compared to CdS, indicating a significant influence of vacancies on the electronic structure of CdS. The defect energy levels formed in the band gap are conducive to electron transfer. The emission peak intensity of the composite material is significantly reduced, indicating that electrons are transferred to the sulfur vacancy 1T-MoS2, which acts as an electron acceptor, improving charge separation efficiency and suppressing electron-hole recombination, which is extremely beneficial to improving photocatalytic activity. Figure 5 B. The extended fluorescence lifetime of sulfur-vacant CdS indicates that the presence of sulfur vacancies leads to an extension of the electronic lifetime. The further extension of the fluorescence lifetime of the composite material is attributed to the rapid injection of electrons from CdS into 1T-MoS2 and the slow recovery of electrons from 1T-MoS2 back to CdS in the composite material. The presence of 1T-MoS2 can improve conductivity, increase electron transport efficiency, effectively suppress carrier recombination, and extend carrier lifetime, which is beneficial to the photocatalytic nitrogen fixation reaction.

[0036] 8. Characterize the physical structure of the catalyst using electron paramagnetic resonance (EPR) to demonstrate the presence of sulfur vacancies. For example... Figure 6 As shown, the sulfur vacancy signal intensity of the composite material is more obvious than that of the sulfur vacancy CdS, indicating that two types of sulfur vacancies exist simultaneously in the composite material, which provides a basis for the synergistic catalysis of the composite material.

[0037] 9. Characterize the electron transfer properties of catalysts using electrochemical tests. For example... Figure 7 A. The composite material has the smallest Nyquist plot radius, indicating that the charge transfer resistance of the sulfur vacancy CdS@sulfur vacancy 1T-MoS2 is small and the electron migration is fast, which is beneficial to the reduction reaction process. For example... Figure 7 B. The composite material exhibits a stronger photoelectric response, indicating a higher electron mobility, which is beneficial for the photocatalytic nitrogen fixation reaction.

[0038] 10. Performance characterization of the catalyst using photocatalytic nitrogen fixation reaction. The sulfur vacancy CdS@sulfur vacancy 1T-MoS2 catalyst exhibited excellent photocatalytic nitrogen fixation activity, with an ammonia formation rate reaching 15730.25 μmol / L. -1 g -1 h -1 It is CdS (5214.39 μmol / L) -1 g -1 h -1 3.02 times that of sulfur vacancy CdS (10924.09 μmol / L) -1 g -1 h -1 1.44 times that of ).

[0039] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A sulfur-vacancy CdS@sulfur-vacancy 1T-MoS2 composite photocatalytic material, characterized in that: It includes sulfur vacancy 1T-MoS2 nanosheets and sulfur vacancy CdS grown in situ on the surface of the sulfur vacancy 1T-MoS2 nanosheets.

2. The preparation method of the sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material as described in claim 1, characterized in that... Includes the following steps: 1) Dissolve ammonium molybdate tetrahydrate and thiourea in deionized water at a mass ratio of 1:0.5-2. The concentration of ammonium molybdate tetrahydrate is 10-20 mg / mL. Stir at room temperature and carry out hydrothermal reaction treatment. Centrifuge the obtained precipitate, wash it, and vacuum dry it overnight to obtain black sulfur vacancy 1T-MoS2 powder. 2) Disperse the 1T-MoS2 powder obtained in step 1) in deionized water / anhydrous ethanol / ethylenediamine, with a volume ratio of deionized water:anhydrous ethanol:ethylenediamine of 1:0.5-1.5:3-5, and a concentration of 1T-MoS2 powder of 0.15-0.5 mg / mL. Disperse the powder evenly by ultrasonication to obtain a mixed solution. 3) Then, cadmium acetate dihydrate and thiourea in a mass ratio of 1:2-5 were dissolved in the above mixed solution. The concentration of cadmium acetate dihydrate was 6-12 mg / mL. The mixture was stirred vigorously at room temperature until homogeneous. Finally, the resulting mixed solution was subjected to hydrothermal reaction treatment. The precipitate was centrifuged, washed, and vacuum dried overnight to obtain a dark green sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material. The mass ratio of sulfur vacancy 1T-MoS2 to sulfur vacancy CdS was 1:10-40.

3. The preparation method of the sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material as described in claim 1, characterized in that... In step 1): the mass ratio of ammonium molybdate tetrahydrate to thiourea is 1:1-1.5, the concentration of ammonium molybdate tetrahydrate is 14-16 mg / mL, the hydrothermal reaction temperature is 160-200 ℃, the hydrothermal reaction time is 10-16 h, and the overnight vacuum drying temperature is 50-80 ℃.

4. The preparation method of the sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material as described in claim 1, characterized in that... In step 2), the volume ratio of deionized water to anhydrous ethanol to ethylenediamine is 1:0.8-1.2:3.5-4, and the concentration of 1T-MoS2 powder is 0.2-0.3 mg / mL.

5. The preparation method of the sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material as described in claim 1, characterized in that... In step 3), the mass ratio of cadmium acetate dihydrate to thiourea is 1:3-4, and the concentration of cadmium acetate dihydrate is 8-10 mg / mL.

6. The preparation method of the sulfur-vacancy CdS@sulfur-vacancy 1T-MoS2 composite photocatalytic material as described in claim 1, characterized in that... In step 3): hydrothermal reaction conditions: hydrothermal reaction temperature is 80-160 ℃; hydrothermal reaction time is 12-36 h; overnight vacuum drying temperature is 50-80 ℃; mass ratio of sulfur vacancy 1T-MoS2: sulfur vacancy CdS is 1:20-30.

7. The application of the sulfur vacancy CdS@sulfur vacancy 1T-MoS2 composite photocatalytic material as described in claim 1 in photocatalytic nitrogen fixation reaction.

8. The application as described in claim 7, characterized in that: At room temperature and pressure, using the composite material as a catalyst, N2 is reduced to NH3 under light irradiation.

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