Reduced graphene oxide-based nano composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photothermal-photocatalytic synergistic materials, and particularly relates to a reduced graphene oxide-based nanocomposite as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, uniformly dispersing a graphene oxide dispersion liquid; s2, adding Ti < 3 > C < 2 > TX MXene, cobalt chloride hexahydrate and thioacetamide into the graphene oxide dispersion liquid to form a uniform reaction system; s3, carrying out hydrothermal reaction on the reaction system obtained in the step S2; s4, soaking and washing a product obtained after the hydrothermal reaction in the step S3; and S5, carrying out freeze drying on a product obtained after washing to obtain the reduced graphene oxide-based nano composite material. According to the preparation method disclosed by the invention, the reduced graphene oxide with more oxygen-containing functional groups reserved on the surface is obtained by utilizing the in-situ auto-oxidation reduction reaction between the graphene oxide and the Ti3C2TX MXene under the condition of not needing additional oxidizing agents and reducing agents, so that the composite material is endowed with good water transmission performance, and the high water evaporation rate is realized.

Description

Technical Field

[0001] This invention belongs to the field of photothermal-photocatalytic synergistic materials technology, and particularly relates to a reduced graphene oxide-based nanocomposite material, its preparation method and application. Background Technology

[0002] The residual organic pollutants in industrial wastewater, due to their structural diversity, biotoxicity, environmental persistence, and resistance to degradation, constitute a complex bottleneck in water treatment technology. Therefore, developing novel sustainable water purification technologies is of significant strategic importance. Currently, wastewater treatment technologies typically rely on non-renewable energy sources such as electricity and chemical energy, which are unsustainable and environmentally unfriendly. Solar energy, an abundant renewable energy source, is considered a substitute for traditional energy. In recent years, significant progress has been made in using solar energy for photothermal conversion to drive interfacial water evaporation technology. However, wastewater usually contains various organic pollutants. High-boiling-point organic pollutants tend to concentrate in the initial water after evaporation, while volatile organic compounds easily evaporate with the water and accumulate in distilled water, causing secondary environmental pollution. Traditional photothermal-driven water evaporation technology struggles to solve this problem. Therefore, the photothermal-photocatalytic synergistic water treatment technology, which introduces photocatalytic materials to degrade various organic pollutants in water, has attracted widespread attention. As a model of efficient solar energy utilization, the photothermal-photocatalytic synergistic water treatment technology provides an innovative solution for the water treatment field. This technology, through the construction of nanostructured materials, achieves efficient water vapor separation while simultaneously degrading pollutants in situ. Compared to traditional reverse osmosis and distillation processes, this interfacial evaporation strategy exhibits significant energy efficiency advantages.

[0003] Graphene, as one of the most representative carbon materials, possesses a unique two-dimensional structure and excellent electron transport properties, enabling it to effectively absorb light energy and rapidly convert it into heat energy, making it an excellent matrix material for photothermal conversion. Zhao et al. successfully prepared anisotropic aerogels with porous structures using graphene oxide nanosheets and polyvinyl alcohol as precursors via directional cryo-casting technology, for photothermal conversion-driven water purification (G. Zhao, Y. Zhang, X. Wang, et al. Anisotropic 3D aerogel of graphene oxide and poly(vinyl alcohol) fordesalination by interfacial solar vapor generation. ACS Applied NanoMaterials 2024, 7, 18870.). Yan et al. developed a reduced graphene oxide / polypyrrole composite photothermal aerogel that integrates full-wavelength light absorption, photothermal effect, and photocatalysis, which is beneficial for synergistically enhancing the thermally assisted photodegradation of volatile organic compound-polluted water, achieving a 2.08 kg m³ [details missing]. -2 h -1 The water evaporation rate and phenol removal efficiency of 94.8% further promote the multifunctional development of solar water purification technology (S. Yan, H. Song, Y. Li, et al. Integrated reduced graphene oxide / polypyrrole hybrid aerogels for simultaneous photocatalytic decontamination and water evaporation. Applied Catalysis B:Environmental 2022, 301, 120820.). TiO2, as a common photocatalyst in recent years, has excellent ultraviolet light absorption capacity, excellent photochemical stability and photocatalytic performance, and low cost, showing broad application potential in the field of catalytic degradation in recent years. Zhu et al. used TiO2 and BiOI as photocatalysts and polyvinyl alcohol as binder to load TiO2 / BiOI composite materials onto melamine foam. Based on the color complementarity of the three primary colors, the light absorption capacity of the composite material was improved. The heterojunction between TiO2 / BiOI composite materials accelerated the separation of photogenerated electrons and holes and increased the reactive sites. Under this synergistic effect, a 2.5 kg m -2 h -1The water evaporation rate and effective degradation of Rhodamine B within 60 minutes were studied (Z. Zhu, T. Wang, S, Ren, et al. Construction of evaporator based on the principle of three primary colors to achieve synchronous photothermal conversion water evaporation and photocatalytic degradation. Desalination2025, 606, 118758.). CoS, as a narrow bandgap semiconductor material, has a series of unique advantages such as wide spectral absorption, high absorption coefficient, low production cost, and good chemical stability. It can absorb light energy in different wavelength spectral ranges, effectively promoting catalytic reactions, and is therefore widely used in water treatment, air purification, and energy conversion. Wan et al. deposited Co metal grains on reduced graphene oxide and single-walled carbon nanotubes as substrates by electrodeposition, and then obtained Co-S / reduced graphene oxide / single-walled carbon nanotube composite materials by sulfidation and hydrogen etching. The composite material showed an evaporation rate of 1.46 kg m³ for pure water under 1 solar irradiance. -2 h -1 It can be applied to wastewater purification in different water environments (Q. Wan, P. Xiang, C. Tang, et al. The defected cobaltsulfide for efficient solar water evaporation: Understanding cobalt-based material induced photothermal conversion. Chemical Engineering Journal, 2025, 163551.).

[0004] In summary, photothermal-photocatalytic synergistic water treatment technology has a certain application foundation. However, based on current research findings, it is difficult to simultaneously achieve high water evaporation rates and high photocatalytic degradation efficiency. This is because, generally, high light absorption capacity of materials requires a narrow band gap and a wide wavelength range corresponding to effective photons. Excitons, after receiving light energy, must undergo transitions, relaxation, and recombination to convert solar energy into thermal energy. However, an excessively small band gap increases the recombination probability of photogenerated electrons and holes, while reducing the redox potential, which contradicts the fact that photocatalytic activity depends on electron-hole separation efficiency. Furthermore, simple physical blending of TiO2 and CoS nanoparticles often leads to uneven distribution and agglomeration of the photocatalyst, reducing the reactive sites for photocatalytic degradation and hindering the photocatalytic reaction. Summary of the Invention

[0005] The main objective of this invention is to provide a reduced graphene oxide-based nanocomposite material, its preparation method, and its application, in order to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: According to a first aspect of the present invention, a method for preparing reduced graphene oxide-based nanocomposite materials is provided, comprising the following steps: S1. Stir and ultrasonically disperse the graphene oxide dispersion until uniform, then set aside. S2, Ti3C2T X MXene, cobalt chloride hexahydrate, and thioacetamide were added to the graphene oxide dispersion obtained in step S1, stirred, and ultrasonically dispersed to form a uniform reaction system. S3. The reaction system obtained in step S2 is subjected to a hydrothermal reaction; S4. Soak and wash the product obtained after the hydrothermal reaction in step S3. S5. The product obtained after washing in step S4 is freeze-dried to obtain the reduced graphene oxide-based nanocomposite material.

[0007] Furthermore, the concentration of the graphene oxide dispersion in step S1 is 4-10 mg / mL.

[0008] Furthermore, in step S2, the graphene oxide and Ti3C2T X The mass ratio of MXene is 2:3-5:4; the mass ratio of graphene oxide to cobalt chloride hexahydrate is 2:1-5:1; and the mass ratio of graphene oxide to thioacetamide is 1:1-5:2.

[0009] Furthermore, in step S3, the hydrothermal reaction is carried out at a temperature of 90-180°C for 3-8 hours.

[0010] Furthermore, in step S4, the soaking and washing involves soaking in distilled water for 48-96 hours.

[0011] Furthermore, in step S5, the freeze-drying time is 24-72 hours.

[0012] According to a second aspect of the present invention, a reduced graphene oxide-based nanocomposite material prepared by any of the above-described preparation methods is provided, the reduced graphene oxide-based nanocomposite material comprising reduced graphene oxide and Ti3C2T X TiO2 generated by in-situ oxidation of MXene, and CoS generated by the reaction of cobalt chloride hexahydrate and thioacetamide.

[0013] Furthermore, the reduced graphene oxide is connected to TiO2 via Ti-OC covalent bonds.

[0014] Furthermore, an S-shaped heterojunction is formed between the CoS and TiO2.

[0015] According to a third aspect of the present invention, the application of the reduced graphene oxide-based nanocomposite material described in any one of the present inventions in photothermal evaporation of water and / or photocatalytic degradation of pollutants is provided.

[0016] Compared with the prior art, the advantages of the present invention include: 1. This invention utilizes graphene oxide and Ti3C2T X The in-situ self-redox reaction between MXenes enables the in-situ reduction of graphene oxide to reduced graphene oxide and Ti3C2T without the need for additional oxidizing and reducing agents. X The in-situ oxidation transformation of MXene to TiO2 yields reduced graphene oxide with more oxygen-containing functional groups on the surface, thereby endowing the composite material with good water transport properties and achieving a high water evaporation rate.

[0017] 2. This invention uses reduced graphene oxide as a substrate and takes advantage of its excellent visible light capture capability to achieve efficient photothermal conversion, thereby endowing the composite material with good photothermal conversion performance.

[0018] 3. This invention utilizes Ti3C2T X MXene, as a reinforcing material, utilizes its good water dispersibility and ease of oxidation to TiO2 to endow the composite material with excellent photocatalytic performance.

[0019] 4. This invention utilizes CoS as a reinforcing material, taking advantage of its excellent broad-spectrum absorption and good chemical stability, thereby endowing the composite material with good photocatalytic performance.

[0020] 5. The CoS prepared by the method of the present invention can effectively adjust the band gap contradiction between materials by constructing an S-type heterojunction with TiO2, broaden the redox potential of the composite material, and improve the photothermal and photocatalytic performance of the material.

[0021] 6. The method of the present invention requires only one hydrothermal synthesis reaction, the equipment is simple, the operation is easy, and it is easy to scale up production. Attached Figure Description

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 Scanning electron microscope image of the reduced graphene oxide-based nanocomposite material prepared in this invention; Figure 2 The photocatalytic degradation rate of pollutants by the reduced graphene oxide-based nanocomposite material prepared by the method of this invention; Figure 3 This is a flowchart of a method for preparing a reduced graphene oxide-based nanocomposite material in a typical embodiment of the present invention. Detailed Implementation

[0023] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0024] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0026] like Figure 1 As shown, this invention provides a method for preparing reduced graphene oxide-based nanocomposite materials, comprising the following steps: S1. Stir and ultrasonically disperse the graphene oxide dispersion until uniform, with a concentration of 4-10 mg / mL, and set aside. S2, Ti3C2TX MXene, cobalt chloride hexahydrate, and thioacetamide were added to the graphene oxide dispersion obtained in step S1, stirred, and ultrasonically dispersed to form a homogeneous reaction system; the graphene oxide reacted with Ti3C2T X The mass ratio of MXene is 2:3-5:4; the mass ratio of graphene oxide to cobalt chloride hexahydrate is 2:1-5:1; the mass ratio of graphene oxide to thioacetamide is 1:1-5:2. S3. The reaction system obtained in step S2 is subjected to a hydrothermal reaction; the temperature of the hydrothermal reaction is 90-180℃, and the time is 3-8 hours. S4. Soak and wash the product obtained after the hydrothermal reaction in step S3; the soaking and washing is done by soaking in distilled water for 48-96 hours. S5. The product obtained after washing in step S4 is freeze-dried to obtain the reduced graphene oxide-based nanocomposite material. The freeze-drying time is 24-72 hours.

[0027] According to a second aspect of the present invention, a reduced graphene oxide-based nanocomposite material prepared by any of the above-described preparation methods is provided, the reduced graphene oxide-based nanocomposite material comprising reduced graphene oxide and Ti3C2T X The reduced graphene oxide is converted into TiO2 by in-situ oxidation of MXene, and CoS is generated by the reaction of cobalt chloride hexahydrate and thioacetamide. The reduced graphene oxide and TiO2 are connected by Ti-OC covalent bonds. An S-type heterojunction is formed between CoS and TiO2.

[0028] According to a third aspect of the present invention, the application of the reduced graphene oxide-based nanocomposite material described in any one of the present inventions in photothermal evaporation of water and / or photocatalytic degradation of pollutants is provided.

[0029] This invention effectively modulates the band gap discrepancy between materials by constructing heterojunctions, while simultaneously improving the photothermal-photocatalytic performance of the materials. A one-step hydrothermal method is used with GO and Ti3C2T... XA reduced graphene oxide-based nanocomposite material was prepared using MXene and cobalt chloride hexahydrate as precursors. This material uses reduced graphene oxide, with its excellent photothermal conversion capabilities, as a framework, and in-situ supports two semiconductor photocatalysts, CoS and TiO2, for synergistic photothermal-photocatalytic water treatment. The in-situ reaction results in a more uniform distribution of CoS and TiO2 compared to traditional physical blending, which provides more reactive sites for photocatalysis, thereby improving the photocatalytic performance. Simultaneously, this invention broadens the redox potential of the composite material by precisely constructing an S-shaped heterojunction between CoS and TiO2. This promotes the recombination of TiO2 electrons and CoS holes while also facilitating the spatial separation of TiO2 holes and CoS electrons, significantly enhancing the synergistic photothermal-photocatalytic ability of the material.

[0030] This invention successfully developed a method based on graphene oxide and Ti3C2T X A multifunctional reduced graphene oxide-based nanocomposite material of MXene and cobalt chloride hexahydrate. The principle lies in the fact that during the in-situ hydrothermal synthesis reaction, the oxygen-containing functional groups (-COOH and -OH) on the surface of graphene oxide first react with H+ in the solution. + Ion formation -C=OH + and -C=OH 2+ Ti-O in MXene - It will attack C=OH + and -C=OH 2+ The carbon atoms in MXene undergo nucleophilic substitution and dehydration reactions, ultimately forming a Ti-OC covalent bond, reducing GO to rGO. Furthermore, during etching and heat treatment, some Ti atoms are exposed in MXene, which are easily oxidized by air and water in high-temperature and humid environments. Therefore, MXene is oxidized to TiO2, serving as the main component of the photocatalyst. This achieves in-situ reduction of graphene oxide to reduced graphene oxide and Ti3C2T… X In-situ oxidation transformation of MXene to TiO2 was achieved. This reduced graphene oxide-based nanocomposite exhibits excellent multifunctional properties. The CoS component, acting as a narrow-bandgap semiconductor, possesses outstanding visible light trapping ability, enabling efficient photothermal conversion. By altering the redox potential of the S-type heterojunction and utilizing the multi-level separation and recombination of charge carriers, the separation efficiency of photogenerated charge carriers is significantly improved, accelerating the photocatalytic reaction kinetics. Performance testing results show that this nanocomposite achieves a thickness of 2.88 kgm³ under simulated sunlight irradiation at one solar intensity. -2 h -1 It exhibits a high water evaporation rate and excellent removal efficiency for a variety of dyes and antibiotics.

[0031] To better understand the technical solution of the present invention, the following detailed discussion is provided in conjunction with specific embodiments.

[0032] Example 1 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, the steps of which are as follows: (1) Stir 10 mL of graphene oxide dispersions of different concentrations and disperse them using ultrasound for 30 minutes, then set aside. (2) 10 mL of Ti3C2T with a mass ratio of 1:1 to graphene oxide was added. X MXene, 20 mg cobalt chloride hexahydrate and 40 mg thioacetamide were added to the solution obtained in step (1), stirred and dispersed by ultrasonication for 10 minutes to form a reaction system; (3) Place the product obtained in step (2) into a hydrothermal reactor and place it in a 120 ℃ oven for 5 h to react; (4) Soak the product obtained in step (3) in distilled water for 72 h to obtain reduced graphene oxide-based hydrogel; (5) Place the product obtained in step (4) in a freeze dryer and freeze dry for 48 h to obtain reduced graphene oxide-based nanocomposite material.

[0033] Figure 2 This is a scanning electron microscope image of the reduced graphene oxide-based nanocomposite material prepared in Example 1 of this invention. As shown in the figure, the porous structure of the reduced graphene oxide can suppress incident light reflection through multiple light scattering and reflection, and the interpenetrating pores can effectively enhance the absorption of sunlight across the entire wavelength range. The porous framework structure significantly reduces the thermal conductivity and improves the mechanical strength of the material. The porous structure and superhydrophilic framework allow water to be rapidly transported to various locations within the material, while the uniform distribution of TiO2 and CoS provides more reactive sites for photocatalysis, thereby improving the photocatalytic performance of the catalyst.

[0034] Figure 3 This is a comparative diagram showing the photocatalytic degradation of pollutants by the reduced graphene oxide-based nanocomposite material prepared in Example 1 of this invention. It can be seen that after 1 hour of adsorption in the dark, the sample and pollutants reached adsorption-desorption equilibrium. Subsequent quantitative analysis showed that the degradation rates of several simulated pollutants, including rhodamine B, methylene blue, tetracycline, and norfloxacin, reached 96%, 97%, 90%, and 85%, respectively, confirming the excellent pollutant removal capacity of the reduced graphene oxide-based nanocomposite material.

[0035] Example 2 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, which differs from Example 1 in that in step (2), 20 mg of cobalt chloride hexahydrate is replaced with 0 mg and 40 mg of thioacetamide is replaced with 0 mg.

[0036] Example 3 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, which differs from Example 1 in that in step (2), 20 mg of cobalt chloride hexahydrate is changed to 10 mg and 40 mg of thioacetamide is changed to 20 mg.

[0037] Example 4 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, which differs from Example 1 in that in step (2), 20 mg of cobalt chloride hexahydrate is changed to 30 mg and 40 mg of thioacetamide is changed to 60 mg.

[0038] Example 5 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, which differs from Example 1 in that in step (2), 20 mg of cobalt chloride hexahydrate is changed to 40 mg and 40 mg of thioacetamide is changed to 80 mg.

[0039] Example 6 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, which differs from Example 1 in that in step (2), 20 mg of cobalt chloride hexahydrate is replaced with 20 mg of cadmium acetate dihydrate.

[0040] Example 7 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, which differs from Example 1 in that in step (2), 20 mg of cobalt chloride hexahydrate is replaced with 20 mg of zinc acetate dihydrate.

[0041] Example 8 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, including the following steps: S1. Stir and ultrasonically disperse the graphene oxide dispersion until it is uniformly dispersed. The concentration of the graphene oxide dispersion is 4 mg / mL. Set aside for later use. S2, Ti3C2T X MXene, cobalt chloride hexahydrate, and thioacetamide were added to the graphene oxide dispersion obtained in step S1, stirred, and ultrasonically dispersed to form a homogeneous reaction system; the graphene oxide reacted with Ti3C2T X The mass ratio of MXene is 2-5; the mass ratio of graphene oxide to cobalt chloride hexahydrate is 1-5; the mass ratio of graphene oxide to thioacetamide is 1-5. S3. The reaction system obtained in step S2 is subjected to a hydrothermal reaction; the temperature of the hydrothermal reaction is 90°C and the time is 3 hours. S4. The product obtained after the hydrothermal reaction in step S3 is soaked and washed; the soaking and washing is done by soaking in distilled water for 48 hours. S5. The product obtained after washing in step S4 is freeze-dried to obtain the reduced graphene oxide-based nanocomposite material. The freeze-drying time is 24 hours.

[0042] Example 9 This embodiment provides a method for preparing reduced graphene oxide-based nanocomposite materials, including the following steps: S1. Stir and ultrasonically disperse the graphene oxide dispersion until it is uniformly dispersed. The concentration of the graphene oxide dispersion is 10 mg / mL. Set aside for later use. S2, Ti3C2T X MXene, cobalt chloride hexahydrate, and thioacetamide were added to the graphene oxide dispersion obtained in step S1, stirred, and ultrasonically dispersed to form a homogeneous reaction system; the graphene oxide reacted with Ti3C2T X The mass ratio of MXene is 3:4; the mass ratio of graphene oxide to cobalt chloride hexahydrate is 2:1; and the mass ratio of graphene oxide to thioacetamide is 1:2. S3. The reaction system obtained in step S2 is subjected to a hydrothermal reaction; the temperature of the hydrothermal reaction is 180°C and the time is 8 hours. S4. The product obtained after the hydrothermal reaction in step S3 is soaked and washed; the soaking and washing is done by soaking in distilled water for 96 hours. S5. The product obtained after washing in step S4 is freeze-dried to obtain the reduced graphene oxide-based nanocomposite material. The freeze-drying time is 72 hours.

[0043] The water evaporation performance parameters of the reduced graphene oxide-based nanocomposites prepared in Examples 1-7 are shown in Table 1. This demonstrates that the water evaporation rate of the reduced graphene oxide-based nanocomposites varies with the amount of cobalt chloride hexahydrate and thioacetamide added.

[0044] Table 1

[0045] The water evaporation rates shown in Table 1 are calculated using the following formula: v = dm / (S × dt); In the formula, v is the evaporation rate, m is the mass of evaporated water, t is the irradiation time, and S is the projected area of ​​the sample directly exposed to simulated sunlight.

[0046] Example 1 exhibits superior water evaporation performance compared to Examples 6 and 7. This is because replacing the precursors with cadmium acetate dihydrate and zinc acetate dihydrate results in cadmium sulfide and zinc sulfide instead of CoS. CoS, a black, narrow-bandgap semiconductor, has a narrower bandgap than cadmium sulfide and zinc sulfide. This narrower bandgap allows CoS to receive a greater number of photons generated by solar radiation. These photons have higher energy than the CoS bandgap, causing CoS to generate electron-hole pairs under irradiation. These pairs then relax to the band edge through thermal relaxation, converting excess energy into heat. Therefore, CoS has better light absorption and photothermal conversion capabilities than other metallic semiconductors such as cadmium sulfide and zinc sulfide, thereby increasing the water evaporation rate per unit time and ultimately achieving a significant increase in freshwater production.

[0047] The above descriptions are merely some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing a reduced graphene oxide-based nanocomposite, characterized by, The method comprises the following steps: S1, stirring and ultrasonic dispersion of graphene oxide dispersion liquid, standby; S2, adding Ti3C2T X MXene, cobalt chloride hexahydrate and thioacetamide are added into the graphene oxide dispersion solution obtained in step S1, stirred and ultrasonically dispersed to form a uniform reaction system; S3, the reaction system obtained in step S2 is subjected to hydrothermal reaction; S4, the product obtained after hydrothermal reaction in step S3 is subjected to soaking and washing; S5, the product obtained after washing in step S4 is subjected to freeze drying to obtain the reduced graphene oxide-based nanocomposite.

2. The production method according to claim 1, characterized by, The concentration of the graphene oxide dispersion liquid in step S1 is 4-10 mg / mL.

3. The production method according to claim 1, characterized by, In step S2, the graphene oxide is mixed with Ti3C2T X The mass ratio of MXene is 2:3-5:4; the mass ratio of graphene oxide to cobalt chloride hexahydrate is 2:1-5:1; the mass ratio of graphene oxide to thioacetamide is 1:1-5:

2.

4. The method of claim 1, wherein, In step S3, the temperature of the hydrothermal reaction is 90-180℃, and the time is 3-8 hours.

5. The preparation method according to claim 1, characterized in that, In step S4, the soaking and washing is performed by using distilled water for 48-96 hours.

6. The method of claim 1, wherein, In step S5, the freeze drying time is 24-72 hours.

7. A reduced graphene oxide-based nanocomposite produced by the method of any one of claims 1-6, characterized in that, The reduced graphene oxide-based nanocomposite comprises reduced graphene oxide, Ti3C2T X TiO2formed in situ from oxidation of MXene, and CoS formed from reaction of cobalt chloride hexahydrate and thioacetamide.

8. The reduced graphene oxide-based nanocomposite of claim 7, wherein the reduced graphene oxide-based nanocomposite is a graphene nanoplatelet-based nanocomposite. The reduced graphene oxide and TiO2 are connected through Ti-O-C covalent bond.

9. The reduced graphene oxide-based nanocomposite of claim 7, wherein the reduced graphene oxide-based nanocomposite is a graphene nanoplatelet-based nanocomposite. The CoS and TiO2 form S-type heterojunction.

10. The reduced graphene oxide-based nanocomposite according to any one of claims 7-9 is used in photothermal evaporation of water and / or photocatalytic degradation of pollutants.

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