A MoS2-COF composite photothermal material and its preparation and application methods

Abstract

The application provides a MoS2-COF composite photothermal material and a preparation and application method thereof, and comprises the following steps: adding a MoS2 water dispersion liquid into acetonitrile to obtain a mixed liquid, wherein the volume ratio of water in the MoS2 water dispersion liquid to the acetonitrile-water solvent system is 0.1-20%; after adding COF monomers into the mixed liquid, the mixed liquid is placed in a normal temperature environment and stirred to obtain a reaction liquid; the reaction liquid is centrifuged, washed and vacuum dried to obtain the MoS2-COF composite photothermal material, so that the COF is two-dimensionally limited on the surface of the MoS2 in a thin, uniform and directional manner in the normal temperature environment.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional heterogeneous composite materials and photothermal conversion materials, specifically to a MoS2-COF composite photothermal material and its preparation and application methods, particularly to a composite photothermal material in which COF is grown in a two-dimensional confined space on the surface of MoS2 under the induction of a water-acetonitrile interface layer and its preparation method. Background Technology

[0002] MoS2, as a typical two-dimensional layered material, possesses certain potential for light absorption and photothermal conversion, but it also has significant intrinsic limitations that severely restrict further improvements in its photothermal performance. On the one hand, pure MoS2 has low light absorption efficiency in the visible-near-infrared region, making it difficult to fully utilize the effective spectral energy for photothermal conversion. On the other hand, single MoS2 nanosheets are prone to van der Waals aggregation, and the stacking of layers destroys its two-dimensional structural advantages, further reducing the contact area between light and the material and exacerbating light absorption losses.

[0003] The inherent properties of covalent organic frameworks can perfectly complement the performance of MoS2, making them ideal materials for modifying MoS2 and improving its photothermal properties: COF has an extended π-conjugated framework structure, which can significantly enhance the absorption of visible and near-infrared light, effectively reduce light reflectivity, and provide a sufficient energy source for photothermal conversion; at the same time, COF can achieve molecular-level structural control through monomer design, and can form ultra-thin and uniform films on the surface of two-dimensional substrates, avoiding aggregation, while retaining the advantages of the two-dimensional structure of the material and increasing the contact area between light and the material.

[0004] However, existing COF growth techniques on MoS2 surfaces have many drawbacks, making it difficult to achieve efficient composite growth. Traditional methods often involve COF growth in organic solvents or under high-temperature solvothermal conditions. These harsh conditions not only exacerbate the aggregation of MoS2 nanosheets but also lead to disordered COF stacking and uncontrollable thickness, making it impossible to achieve ultrathin, uniform, and directional two-dimensional confined growth of COF on MoS2 surfaces at room temperature. At the same time, traditional growth methods also result in poor heterogeneous interface bonding between MoS2 and COF, uncontrollable COF thickness, and an inability to form stable interfacial coupling, ultimately making it difficult to improve the photothermal conversion efficiency of the composite system.

[0005] Therefore, it is urgent to construct a MoS2-COF heterostructure with strong interfacial coupling to achieve precise confined growth of COF on the MoS2 surface, thereby significantly improving the light absorption and photothermal conversion efficiency of the composite material. Summary of the Invention The purpose of this invention is to provide a MoS2-COF composite photothermal material and its preparation and application method, which achieves the effect of ultra-thin, uniform, and directional two-dimensional confinement of COF on the surface of MoS2 at room temperature, and can construct a MoS2-COF composite photothermal material with strong interfacial coupling to significantly improve its light absorption and photothermal conversion efficiency.

[0006] To achieve the above objectives, this technical solution provides a method for preparing MoS2-COF composite photothermal material, comprising the following steps: A mixture was obtained by adding MoS2 aqueous dispersion to acetonitrile, wherein the water in the MoS2 aqueous dispersion accounted for 0.1~20% of the volume of the acetonitrile-water solvent system; After adding COF monomer to the mixture, the mixture was stirred at room temperature to obtain a reaction solution. The reaction solution was centrifuged, washed, and vacuum dried to obtain the MoS2-COF composite photothermal material.

[0007] This scheme enables two-dimensional confined growth of COF on the surface of MoS2 at room temperature (25℃). The core reason is that it abandons the traditional high-temperature solvothermal / pure organic solvent reaction-driven mode and constructs a microenvironment regulation and interface-induced polymerization mechanism for the water-based interface adsorption layer. It achieves controllable growth at room temperature from three aspects: reaction kinetics, growth sites, and polymerization rate.

[0008] Specifically, the solvent system composed of water and acetonitrile in this scheme forms a water-based interfacial adsorption layer with compatible hydrophilic / hydrophobic properties on the surface of MoS2 nanosheets. The MoS2 surface has a certain degree of hydrophobicity, acetonitrile serves as the continuous phase of the organic solvent, and trace amounts of water are directionally adsorbed on the MoS2 surface to form aqueous micro-regions. Due to the hydrophilic-hydrophobic interaction, COF monomers are directionally enriched and orderly arranged in this water-based interfacial adsorption layer, resulting in a local monomer concentration much higher than that in the bulk solution. This significantly increases the contact probability and reaction efficiency between monomers. The interfacial enrichment effect replaces the molecular motion acceleration effect of high temperature, allowing condensation polymerization to occur efficiently at room temperature. In addition, through the interfacial anchoring and two-dimensional planar confinement of the water-based interfacial adsorption layer, the polymerization reaction of COF can only occur in the two-dimensional space on the surface of the MoS2 nanosheets. This avoids the random free polymerization that easily occurs in the bulk solution at room temperature and achieves directional growth.

[0009] Preferably, the mixture contains surface-pretreated MoS2, wherein the surface-pretreated MoS2 forms a water-based interfacial adsorption layer on the surface of MoS2.

[0010] Furthermore, the water-based interface adsorption layer includes an aqueous micro-interface layer adsorbed on the surface of MoS2, and an acetonitrile molecular layer coating the outside of the aqueous micro-interface layer.

[0011] Furthermore, the aqueous micro-interface layer is formed through hydrogen bonds and dipole interactions between water molecules and hydrophilic sites at the edges of the MoS2 sheets, while the acetonitrile molecular layer is formed through hydrophilic interactions between acetonitrile and the aqueous micro-interface layer, as well as van der Waals adsorption.

[0012] Using Carl Trace amounts of water were determined using a Fischer coulometric titrator to obtain the change in water content in the bulk solution before and after adsorption. The volume of water adsorbed on the MoS2 nanosheet surface was calculated by subtracting the water content before adsorption from the water content after adsorption. Combined with the surface area of ​​the MoS2 nanosheets, the thickness (d) of the surface water adsorption layer was calculated according to the following formula:

[0013] In the formula, V 水 The volume of water adsorbed on the MoS2 surface (nm) 3 S is the surface area of ​​the MoS2 nanosheet (nm). 2 ).

[0014] Moisture measurement results show that when the volume fraction of H2O is 0.5%, a water adsorption layer with a thickness of about 0.5~2.0 nm can be formed on the surface of MoS2 nanosheets. This thickness is significantly higher than the scale of a monolayer water layer, indicating that water molecules form a stable solvation layer structure on the surface of MoS2 through a hydrogen bond network, rather than a simple monolayer adsorption.

[0015] Preferably, the water content in the water-acetonitrile mixed solvent is 0.5% by volume. This solution contains only trace amounts of water in the water-acetonitrile mixed solvent. This trace amount of water ensures the formation of a continuous and stable aqueous micro-interface layer on the MoS2 surface, providing a core microenvironment for the directional enrichment and room-temperature confined growth of COF monomers. Simultaneously, it avoids the problems of MoS2 aggregation and COF bulk polymerization caused by excessive water content, while insufficient water content prevents the formation of an effective water-based interface adsorption layer, thus failing to achieve the two-dimensional confined growth effect of this solution.

[0016] Preferably, the MoS2 aqueous dispersion is a dispersion obtained by dispersing MoS2 in water. Specifically, pure MoS2 nanosheets are first added to deionized water and ultrasonically dispersed. The shear force of the ultrasound breaks down the van der Waals agglomerates of MoS2, forming a monodisperse MoS2 aqueous dispersion. At this time, the hydrophilic sites at the edges of the MoS2 sheets will form hydrogen bonds and dipole interactions with water molecules, and water molecules will preferentially adsorb at the edges of MoS2. At the same time, a small number of water molecules are adsorbed at the hydrophobic sites on the basal surface due to van der Waals forces, forming a thin hydration film, allowing MoS2 to be stably dispersed in water.

[0017] Preferably, the concentration of the MoS2 aqueous dispersion in the mixture is 0.05~0.2 g / L.

[0018] More preferably, the concentration of the MoS2 aqueous dispersion in the mixture is 0.1 g / L.

[0019] Preferably, after adding COF monomer to the mixture, the mixture is stirred at room temperature to obtain a reaction solution, wherein the total mass ratio of MoS2 and COF monomer in the MoS2 aqueous dispersion is 1:(0.5~10).

[0020] More preferably, the total mass ratio of MoS2 to COF monomers in the MoS2 aqueous dispersion is 1:1.

[0021] This scheme does not restrict the type of COF monomer; that is, the preparation method of the MoS2-COF composite photothermal material provided in this scheme can be applied to a variety of COF monomers.

[0022] Preferably, the COF monomer includes an amino functional monomer and an aldehyde functional monomer, wherein the amino functional monomer is selected from 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) and tris(4-aminophenyl)amine (TAPA), and the aldehyde functional monomer is selected from 2,4,6-trialdehyde phloroglucinol (TFP) and 1,3,5-benzenetriformaldehyde (BTCA).

[0023] Preferably, the COF monomer includes any one of TAPT-TFP, TAPA-TFP, TAPB-TFP, and TAPB-BTCA.

[0024] Preferably, the reaction solution is obtained by adding COF monomer to the mixture and stirring at 25°C for 2-48 hours. More preferably, the reaction solution is obtained by adding COF monomer to the mixture and stirring at 25°C for 12 hours.

[0025] Secondly, this solution provides a MoS2-COF composite photothermal material prepared according to the first aspect, comprising MoS2 and a COF layer confined and grown on MoS2.

[0026] Preferably, the thickness of the COF layer on the MoS2-COF composite photothermal material is 1~2 nm, and it does not affect the morphology of the MoS2 sheets.

[0027] Preferred MoS2-COF composite photothermal material exhibits a photothermal temperature rise of up to 109.8 ℃, which is far superior to pure MoS2 (65.2 ℃), and a visible-near-infrared reflectivity as low as 4.6%, demonstrating extremely strong light-trapping ability.

[0028] Preferably, the MoS2-COF composite photothermal material has a uniform sheet structure with a thickness of 2.5~3nm.

[0029] More preferably, the thickness of the MoS2-COF composite photothermal material is 2.8 nm.

[0030] Thirdly, this solution provides an application of the MoS2-COF composite photothermal material prepared according to the first aspect, which can be widely used in multiple fields related to photothermal conversion, such as energy, environment, industry, and civil use.

[0031] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects: This method addresses the shortcomings of existing COF growth on MoS2 surfaces, which relies on harsh conditions such as high-temperature solvothermal processes and high pressures. This method allows the reaction to proceed at room temperature and pressure, eliminating the need for specialized high-temperature and high-pressure equipment. Furthermore, by constructing a water-based interfacial adsorption layer using trace amounts of water and acetonitrile, it achieves ultrathin, uniform, two-dimensional confined growth of COF on the MoS2 surface at a depth of 1–2 nm, fully preserving the MoS2 sheet morphology, preventing agglomeration and bulk free polymerization, and resulting in excellent product structural uniformity. The final MoS2-COF composite photothermal material prepared by this method exhibits strong chemical coupling between MoS2 and COF via Mo–N covalent bonds, significantly reducing interfacial energy loss. The composite material boasts a visible-near-infrared reflectivity as low as 4.6%, a maximum photothermal temperature rise of 109.8℃, and significantly superior light capture and photothermal conversion efficiencies compared to existing similar materials. Attached Figure Description

[0032] Figure 1 SEM images of composite photothermal materials prepared by MoS2 and COF monomer mass ratios of 1:5, 1:10, and a control experiment. Figure 2 These are SEM images and EDS mapping results of a composite photothermal material with a MoS2 and COF monomer mass ratio of 1:1.

[0033] Figure 3 This is the AFM diagram of a composite photothermal material with a MoS2 and COF monomer mass ratio of 1:1.

[0034] Figure 4 These are SEM images and EDS mapping results of the composite photothermal material obtained from the control experiment.

[0035] Figure 5 This is the FTIR image of a composite photothermal material with a MoS2 and COF monomer mass ratio of 1:1.

[0036] Figure 6 This is the XRD pattern of a composite photothermal material with a MoS2 and COF monomer mass ratio of 1:1.

[0037] Figure 7 This is the XPS image of a composite photothermal material with a MoS2 and COF monomer mass ratio of 1:1.

[0038] Figure 8 These are the photothermal heating curves of composite photothermal materials with different mass ratios of MoS2 and COF monomers.

[0039] Figure 9 These are the photothermal heating curves of composite photothermal materials with different COF monomers and MoS2 and COF monomers.

[0040] Figure 10 These are spectral test images of composite photothermal materials with different COF monomers and MoS2 and COF monomers.

[0041] Figure 11 These are the photothermal temperature rise curves of composite photothermal materials corresponding to different COF monomers. Detailed Implementation

[0042] The chemical reagents involved in this solution are all conventional raw materials disclosed in the prior art. Their purity and specifications can be adjusted according to actual experimental / production needs. Any selection of raw materials that can achieve the technical effect of this solution falls within the protection scope of this invention. Unless otherwise specified, the experimental conditions in the following examples are all carried out according to conventional conditions in the prior art or according to the conditions recommended by the reagent / equipment manufacturer; unless otherwise specified, the raw materials used are all commercially available conventional products.

[0043] Example 1: Verifying the effect of different mass ratios of MOS2 and COF monomers: The selected COF monomers are 1,3,5-tris(4-aminophenyl)benzene (TAPB) and pyromellitic trimethylolpropane (BTCA).

[0044] Designs with different mass ratios: The mass ratio of MoS2 nanosheets to the total mass of the two COF monomers was set as follows: 2:1 (10 mg of molybdenum disulfide nanosheets, 5 mg of COF monomers in a 1:1 molar ratio), 1:1 (5 mg of molybdenum disulfide nanosheets, 5 mg of COF monomers in a 1:1 molar ratio), 1:2 (5 mg of molybdenum disulfide nanosheets, 10 mg of COF monomers in a 1:1 molar ratio), 1:5 (5 mg of molybdenum disulfide nanosheets, 25 mg of COF monomers in a 1:1 molar ratio), and 1:10 (5 mg of molybdenum disulfide nanosheets, 50 mg of COF monomers in a 1:1 molar ratio).

[0045] Preparation method: Prepare a MoS2 aqueous dispersion by adding 0.5% (v / v) of the MoS2 aqueous dispersion to ACN to form a mixed solvent dispersion system. Control the MoS2 concentration in the system to be 0.1 g / L. Then add two COF monomers and react at 25℃ for 12 h. Centrifuge, wash, and dry the reaction product for later use.

[0046] Test method: SEM observation was performed on composite photothermal materials prepared with different MOS2 and COF monomer mass ratios and control experiments. The SEM image of the composite photothermal material with a MOS2 to COF monomer mass ratio of 1:1 is shown below. Figure 2 As shown, the SEM images of the composite photothermal materials prepared by the MOS2 and COF monomer mass ratios of 1:5 and 1:10, respectively, and the control experiment are shown in the figure. Figure 1 As shown.

[0047] Experimental results: such as Figure 1 As shown, when the mass ratio of MOS2 to COF monomers is 1:5, SEM observations show a significant increase in the thickness of the sheets and the appearance of a small number of lumps in some areas. The essence of this phenomenon is that as the concentration of COF monomers increases, the regulatory effect of the interface layer on the local concentration of COF monomers is weakened, leading to an accelerated local polymerization rate. In some areas, the COF film grows too thick, exceeding the coverage of the single layer, resulting in slight agglomeration. However, the overall two-dimensional confinement effect is not completely destroyed, so some sheet-like structures are retained. When the mass ratio of MOS2 to COF monomers is further increased to 1:10, the sheet morphology completely disappears, and the confinement effect of the system is completely destroyed. SEM characterization shows that the product completely loses its sheet morphology, forming a large number of irregular spherical COF particles, accompanied by the agglomeration of MoS2 nanosheets. The reason for this is that the excessively high monomer concentration causes the polymerization rate of COF monomers to far exceed the control capability of the interface layer. The polymerization reaction is no longer limited by the two-dimensional interface on the MoS2 surface, but instead becomes a free polymerization in the bulk phase. A large number of COF monomers randomly polymerize in the solution to form spherical particles. At the same time, the excessive COF monomers will also destroy the water-based interface adsorption layer structure induced by the H2O-ACN mixed solvent, causing the MoS2 nanosheets to lose the protection of the interface layer. The van der Waals stacking forces between the layers are enhanced, resulting in agglomeration and ultimately losing the sheet-like morphology. This result further confirms the importance of the interface layer confinement effect and the key significance of monomer concentration control.

[0048] Example 2: Verification of the effect of the solvent system: The selected COF monomers are 1,3,5-tris(4-aminophenyl)benzene (TAPB) and pyromellitic trimethylolpropane (BTCA).

[0049] Experiment: A MoS2 aqueous dispersion was prepared by adding 0.5% (v / v) MoS2 aqueous dispersion to ACN to form a mixed solvent dispersion system. The MoS2 concentration in the system was controlled at 0.1 g / L. Subsequently, two COF monomers (5 mg of molybdenum disulfide nanosheets, with a COF monomer molar ratio of 1:1) were added, and the reaction was carried out at 25 °C for 12 h. The reaction product was centrifuged, washed, and dried for later use.

[0050] Control experiment: Repeat the above steps in pure ACN.

[0051] The SEM images and EDS mapping results of the composite photothermal material with a MOS2 to COF monomer mass ratio of 1:1 obtained in this experiment are as follows: Figure 2 As shown in the figure, the AFM measurement results are as follows: Figure 3 As shown, the SEM images and EDS mapping results of the composite photothermal material obtained from the control experiment are as follows: Figure 4 As shown.

[0052] As can be seen, when the total mass ratio of MoS2 to the two COF monomers is 1:1, SEM characterization results show that the product maintains a complete sheet-like structure, and its morphology is basically consistent with that of pure MoS2 nanosheets, without obvious agglomeration or spherical particles. This indicates that under this condition, the growth of COF did not destroy the MoS2 sheets, achieving two-dimensional directional growth. EDS mapping results show that the characteristic element of COF (N element) is uniformly distributed throughout the sheet-like structure region, without obvious enrichment or deficiency. Moreover, the distribution range of N element completely overlaps with that of Mo and S elements, further confirming that the COF monomers underwent a uniform polymerization reaction on the MoS2 surface. The formed COF film has good uniformity and continuity, fully verifying the effectiveness and uniformity of COF confined growth induced by the water-based interface adsorption layer. AFM measurements further show that the average thickness of this sheet-like structure is approximately 2–3 nm. Based on the thickness of the monolayer MoS2 nanosheets (approximately 1 nm), it can be clearly inferred that a COF film with a thickness of approximately 1–2 nm was uniformly grown on the surface of MoS2, forming a two-dimensional composite structure (MoS2-COF) with a monolayer COF covering MoS2.

[0053] The composite photothermal material obtained in the control experiment consisted of numerous small spherical particles encapsulated in layers. Based on the experimental phenomena and reaction mechanism, the formation process of this structure can be inferred as follows: In the absence of the regulatory effect of a water-induced interface layer, COF monomers preferentially undergo free polymerization in the bulk solution to form spherical COF particles. Subsequently, the unstable MoS2 nanosheets in the system, lacking the protection of the interface layer, easily aggregate and randomly embed themselves on the surface of the spherical COF particles, ultimately forming the special morphology of layers encapsulating small spheres. EDS mapping characterization results further corroborate this hypothesis. The characteristic N element signal of the COF monomer in this sample is very weak, to the point of being difficult to detect, indicating that the COF monomers did not achieve uniform polymerization and directional growth on the MoS2 surface. This fully confirms that the absence of a water-induced interface layer leads to the inability to achieve directional confined growth of two-dimensional COF, further highlighting the effectiveness of the H2O-ACN mixed solvent-induced interface layer regulation strategy.

[0054] Example 3, Physicochemical Performance Test: Following Example 2, the composite photothermal material prepared by setting the mass ratio of MoS2 nanosheets to the total mass of the two COF monomers in Example 2 to 1:1 was subjected to FTIR testing, and the FTIR test results are shown in the figure below. Figure 5 As shown, the XRD test results are as follows: Figure 6 As shown, the XPS spectrum obtained by XPS spectral analysis is as follows. Figure 7 As shown.

[0055] FTIR test results show that the product is at 1625 cm⁻¹ - A distinct characteristic absorption peak appears at ¹, corresponding to the stretching vibration of the imine bond (C=N), confirming that COF successfully constructed a covalent network structure on the MoS2 surface. XRD patterns show that the pure MoS2 sample exhibits typical diffraction peaks of the (002), (100), and (110) crystal planes at 2θ≈14°, 33°, and 59°, respectively. These peaks are broadened and weaker, indicating a few-layer or nanocrystalline structure. Compared to pure MoS2, the characteristic peak intensity of MoS2 in the MoS2-COF composite material is significantly reduced, and the peak shape is further broadened. Simultaneously, new sharp and strong diffraction peaks appear at 2θ≈20° and 24°, which can be attributed to the characteristic crystalline phase of COF, proving that COF has been successfully composited with good crystallinity. These results demonstrate that by compositing with COF, the layered structure of MoS2 can be effectively controlled, and a MoS2-COF composite system with excellent crystallinity can be successfully prepared.

[0056] In XPS testing, the N 1s high-resolution spectrum could be fitted with three characteristic peaks, with binding energies of 398.33, 399.70, and 401.59 eV, respectively, corresponding to the imine bond C=N in the COF skeleton, the Mo–N coordination bond formed at the interface, and the -NH group. The Mo–N characteristic peak at 399.70 eV directly proves that MoS2 and COF are chemically coupled through Mo–N covalent bonds. Changes in CO and C=O signals in the C 1s spectrum further confirm the interaction between the interfacial functional groups; the S2² signal in the S 2p spectrum... - The significantly increased proportion indicates that the interfacial reaction altered the chemical environment of sulfur species on the MoS2 surface, and the S² content on the MoS2 surface... - Oxidation or nucleophilic reactions occur, accompanied by cross-interfacial charge transfer. These results fully confirm that MoS2 and COF are not simply physical composites, but rather form a stable chemical bond through Mo–N bonding and interfacial electron transfer.

[0057] Example 4: Photothermal testing of composite photothermal materials with different mass ratios of MOS2 and COF monomers: The selected COF monomers are 1,3,5-tris(4-aminophenyl)benzene (TAPB) and pyromellitic trimethylolpropane (BTCA).

[0058] The mass ratios of MoS2 nanosheets to the total mass of the two COF monomers were set as follows: 2:1 (10 mg of molybdenum disulfide nanosheets, 5 mg of COF monomers in a 1:1 molar ratio), 1:1 (5 mg of molybdenum disulfide nanosheets, 5 mg of COF monomers in a 1:1 molar ratio), 1:2 (5 mg of molybdenum disulfide nanosheets, 10 mg of COF monomers in a 1:1 molar ratio), 1:5 (5 mg of molybdenum disulfide nanosheets, 25 mg of COF monomers in a 1:1 molar ratio), and 1:10 (5 mg of molybdenum disulfide nanosheets, 50 mg of COF monomers in a 1:1 molar ratio).

[0059] Preparation method: Prepare a MoS2 aqueous dispersion by adding 0.5% (v / v) of the MoS2 aqueous dispersion to ACN to form a mixed solvent dispersion system. Control the MoS2 concentration in the system to be 0.1 g / L. Then add two COF monomers and react at 25℃ for 12 h. Centrifuge, wash, and dry the reaction product for later use.

[0060] 1. Test method: The photothermal test uses a broadband infrared lamp (760nm–5μm, 1000W / m). 2 Using [a specific light source], composite samples with different mass ratios and pure MoS2 samples were subjected to the same irradiation time (100 s irradiation followed by 100 s cooling with the light off). The sample temperature changes were monitored in real time, and the photothermal heating curves were obtained as shown below. Figure 8 As shown, 1MoS2-1COF represents a composite photothermal sample prepared with a MoS2 to COF monomer mass ratio of 1:1, 1MoS2-2COF represents a composite photothermal sample prepared with a MoS2 to COF monomer mass ratio of 1:2, 1MoS2-5COF represents a composite photothermal sample prepared with a MoS2 to COF monomer mass ratio of 1:5, 1MoS2-10COF represents a composite photothermal sample prepared with a MoS2 to COF monomer mass ratio of 1:10, and 2MoS2-1COF represents a composite photothermal sample prepared with a MoS2 to COF monomer mass ratio of 2:1.

[0061] 2. Test results show that the photothermal conversion performance of composite samples with different mass ratios varies significantly: 1MoS2-1COF (a two-dimensional confined structure covered by a single layer of COF) with a MoS2 to COF monomer mass ratio of 1:1 reaches a maximum temperature of 130.2 ℃ at the end of illumination, with a temperature rise (ΔT = T-T0, where T is the real-time temperature and T0 is the initial temperature) of 109.8 ℃, significantly higher than the maximum temperature rise of pure MoS2 nanosheets (65.2 ℃). The maximum temperature of 1MoS2-2COF with a mass ratio of 1:2 is 104.1 ℃, slightly lower than 1MoS2-1COF but still higher than pure MoS2. 2MoS2-1COF with a mass ratio of 2:1 cannot form a complete single-layer covered structure due to insufficient COF monomer content, and its maximum temperature rise is 72.6 ℃. The temperature rise of 1MoS2-1COF is weaker than that of 1MoS2-2COF; the maximum temperature rise of 1MoS2-5COF and 1MoS2-10COF is 95.0 ℃ and 75.0 ℃ respectively, and the photothermal performance decreases in that order.

[0062] Example 5: Photothermal testing of photothermal composites with different COF monomers: To further improve the comparison system, the photothermal properties of the film-pulling of MoS2-TAPB, MoS2-BTCA and samples synthesized in pure ACN solvent were tested simultaneously under a 1:1 mass ratio.

[0063] The selected COF monomers are: TAPB-BTCA, TAPB, and BTCA. The mass ratio of MoS2 nanosheets to total COF monomers was set to 1:1 (5 mg of molybdenum disulfide nanosheets and 5 mg of COF monomers were added when the molar ratio was 1:1).

[0064] Preparation method: Prepare a MoS2 aqueous dispersion by adding 0.5% (v / v) of the MoS2 aqueous dispersion to ACN to form a mixed solvent dispersion system. Control the MoS2 concentration in the system to be 0.1 g / L. Then add COF monomer and react at 25 °C for 12 h. Centrifuge, wash, and dry the reaction product for later use.

[0065] 3. Test Method: The photothermal test uses a broadband infrared lamp (760nm–5μm, 1000W / m). 2 Using [a specific light source], composite samples with different mass ratios and pure MoS2 samples were subjected to the same irradiation time (100 s irradiation followed by 100 s cooling with the light off). The sample temperature changes were monitored in real time, and the photothermal heating curves were obtained as shown below. Figure 8As shown, MoS2-BTCA is a COF product with only BTCA monomers, MoS2-TAPB is a COF product with only TAPB monomers, and 1MoS2-1COF is a COF product with both BTCA and TAPB monomers.

[0066] Control experiment: Repeat the above steps in pure ACN.

[0067] The test results show that, under a 1:1 mass ratio, the highest temperature rise of the MoS2-BTCA sample is approximately 65.0 ℃, which is similar to the highest temperature of pure MoS2 nanosheets, indicating that simply introducing BTCA cannot effectively improve the photothermal performance of MoS2. The highest temperature rise of the MoS2-TAPB sample is 80.9 ℃, which is higher than that of pure MoS2 but significantly lower than that of the 1MoS2-1COF sample. The sample synthesized in pure ACN has a sheet-encapsulated spherical structure, with a highest temperature rise of only 59.1 ℃, slightly lower than that of pure MoS2. Its photothermal performance has not been improved but has even decreased slightly, indicating that its disordered structure not only cannot optimize photothermal performance but may also lead to increased energy loss due to structural defects. The above results further confirm that the two-dimensional confined structure formed by monolayer COF coverage is most conducive to improving photothermal conversion efficiency, and a 1:1 mass ratio is the optimal ratio.

[0068] Example 6, Reflectivity Test: To explore the underlying reasons for the improved photothermal conversion efficiency, the light absorption capacity of the sample was first analyzed through reflectivity testing.

[0069] The selected COF monomers are: TAPB-BTCA, TAPB, and BTCA. The mass ratio of MoS2 nanosheets to total COF monomers was set to 1:1 (5 mg of molybdenum disulfide nanosheets and 5 mg of COF monomers were added when the molar ratio was 1:1).

[0070] Preparation method: Prepare a MoS2 aqueous dispersion by adding 0.5% (v / v) of the MoS2 aqueous dispersion to ACN to form a mixed solvent dispersion system. Control the MoS2 concentration in the system to be 0.1 g / L. Then add COF monomer and react at 25 °C for 12 h. Centrifuge, wash, and dry the reaction product for later use.

[0071] Test method: To analyze the reflectance differences of the MoS2-based composite system, the reflectance of the composite material uniformly deposited on the polytetrafluoroethylene film was tested using the integrating sphere attachment of the ultraviolet spectrophotometer. Among them, MoS2-BTCA is a COF product with only BTCA monomer, MoS2-TAPB is a COF product with only TAPB monomer, MoS2-COF is a COF product with both BTCA and TAPB monomers, and MoS2 is pure MoS2.

[0072] The test results show that the reflectance of the four samples in the visible to near-infrared region (500–1400 nm, which is the effective spectral range for photothermal conversion) is as shown in Table 1 below: Table 1. Reflectance of different samples in the 500-1400 nm range .

[0073] It is evident that there are significant differences in reflectivity among the four samples. The MoS2-1COF sample has the lowest reflectivity (4.6%), indicating that the monolayer uniform COF film can effectively suppress light reflection and significantly enhance the absorption efficiency of visible and near-infrared light, providing a sufficient energy source for photothermal conversion. This is one of the important reasons for its highest photothermal conversion efficiency. The reflectivity of the MoS2-TAPB sample is 9.4%, lower than that of pure MoS2 (18.0%) but higher than that of MoS2-COF, indicating that the introduction of TAPB can slightly improve the light absorption capacity of MoS2, but the effect is limited. The reflectivity of the MoS2-BTCA sample is 15.5%, similar to that of pure MoS2 (18.0%), indicating that the introduction of BTCA alone cannot effectively improve the light absorption performance of MoS2. This also corresponds to the test results that its photothermal performance is basically consistent with that of pure MoS2.

[0074] Example 7, Spectral Testing: Following Example 6, to analyze the optical response and energy dissipation behavior of the MoS2-based composite system, this experiment simultaneously conducted steady-state photoluminescence emission and excitation spectra measurements on three samples: pure MoS2, MoS2-TAPB, and MoS2-COF. The test results are shown in the figure below. Figure 9 As shown, MoS2-TAPB is a COF product with only TAPB monomers, MoS2-COF is a COF product with BTCA and TAPB monomers, and MoS2 is pure MoS2.

[0075] PL emission spectroscopy results showed that pure MoS2 exhibited only a weak and broad emission peak in the visible region, consistent with its indirect bandgap characteristics and the dominance of nonradiative recombination in the system. After introducing TAPB, the PL emission intensity of the MoS2-TAPB composite further decreased, indicating that the interfacial interaction between TAPB and MoS2 effectively introduced additional nonradiative relaxation channels, suppressing exciton radiative recombination. Notably, despite the weakened PL emission, MoS2-TAPB showed superior heating performance compared to pure MoS2 in photothermal tests, suggesting that photoexcitation energy is more likely to be converted into heat energy through nonradiative pathways rather than released as photons. This also explains the limited increase in reflectivity but the improved photothermal performance. Further construction of a TAPB-BTCA covalent organic framework on the MoS2 surface significantly enhanced the excitation spectral intensity in the UV-Vis region, indicating that the introduction of COF significantly improved the system's light-harvesting ability. This is mainly attributed to the extended π-conjugated structure in COF, which is highly consistent with the aforementioned test results showing the lowest reflectivity of the MoS2-COF sample. However, compared to the significant enhancement in excitation capability, the emission spectrum of MoS2-COF did not show a corresponding enhancement in the intrinsic exciton emission of MoS2. Instead, it exhibited a spectral morphology characterized by broadband emission, which is more likely to originate from COF or interface-related states. The obvious mismatch between the excitation and emission spectra indicates that the light energy absorbed by the MoS2-COF composite system is not mainly released through radiative recombination, but is preferentially dissipated through non-radiative pathways such as interface charge transfer and vibrational relaxation, thereby achieving efficient photothermal conversion. This energy relaxation mechanism dominated by non-radiative processes is highly consistent with the significant heating performance exhibited by the MoS2-COF composite in photothermal experiments, further corroborating the optimizing effect of the two-dimensional confined structure on photothermal performance.

[0076] Example 8: Testing of different COF monomers: The selected COF monomers are: TAPT-TFP, TAPA-TFP, and TAPB-TFP. The mass ratio of MoS2 nanosheets to the total mass of the two COF monomers was set to 1:1 (5 mg of molybdenum disulfide nanosheets and 5 mg of COF monomers were added when the molar ratio was 1:1).

[0077] Preparation method: Prepare a MoS2 aqueous dispersion by adding 0.5% (v / v) of the MoS2 aqueous dispersion to ACN to form a mixed solvent dispersion system. Control the MoS2 concentration in the system to be 0.1 g / L. Then add two COF monomers and react at 25℃ for 12 h. Centrifuge, wash, and dry the reaction product for later use.

[0078] Test method: Photothermal testing was performed using a broadband infrared lamp (760nm–5μm, 1000W / m). 2 Using COF as the light source, composite samples with different mass ratios and pure MoS2 samples were subjected to the same illumination time (100 s irradiation followed by 100 s cooling with the light off). The temperature change of the samples was monitored in real time, and the photothermal heating curves of the composite photothermal materials corresponding to different COF monomers were obtained as follows: Figure 10 As shown.

[0079] The test results clearly show that the MoS2-COF composite samples prepared by the three different COF monomer combinations all exhibited significant photothermal heating effects. The maximum temperature rise at the end of illumination was 97.5 ℃ for MoS2-TAPT-TFP, 87.3 ℃ for MoS2-TAPA-TFP, and 86.0 ℃ for MoS2-TAPB-TFP, all significantly higher than the maximum temperature rise of the pure MoS2 sample (65.2 ℃). While there were slight differences in the heating effects among the three composite samples, the overall trend was consistent, and all achieved effective improvement in photothermal performance. This result directly confirms that the water-based interfacial adsorption layer-induced confined growth strategy is applicable to three different COF monomer structures (TAPT-TFP, TAPA-TFP, and TAPB-TFP), and can stably optimize the photothermal performance of MoS2, fully demonstrating the universality of this strategy.

[0080] It should be noted that TAPB has a benzene ring as its core and a relatively rigid structure; TAPT has a triazine ring as its core, a higher nitrogen content, a stronger electron attraction effect, and better planarity; TAPA has a tertiary amine as its core, greater conformational freedom, and more pronounced electron donor characteristics. These differences will affect the condensation reaction kinetics and the degree of skeletal order. Unlike BTCA, which only forms imine bonds, TFP can undergo enol-ketone tautomerism after condensation, forming a stable β-ketoenamine structure, improving the degree of skeletal conjugation and chemical stability. Therefore, the above systems exhibit systematic differences in central skeleton type, electronic effects, and bonding forms. By validating the confined growth strategy in these COF systems with different structural backgrounds, it can be further demonstrated that this method has good adaptability and universality for multiple types of two-dimensional COF networks.

[0081] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing a MoS2-COF composite photothermal material, characterized in that, Includes the following steps: A mixture was obtained by adding MoS2 aqueous dispersion to acetonitrile, wherein the water in the MoS2 aqueous dispersion accounted for 0.1~20% of the volume of the acetonitrile-water solvent system; After adding COF monomer to the mixture, the mixture was stirred at room temperature to obtain a reaction solution. The reaction solution was centrifuged, washed, and vacuum dried to obtain the MoS2-COF composite photothermal material.

2. The preparation method of the MoS2-COF composite photothermal material according to claim 1, characterized in that, The mixture contains surface-pretreated MoS2, wherein the surface-pretreated MoS2 forms a water-based interface adsorption layer on the surface of MoS2. The water-based interface adsorption layer includes an aqueous micro-interface layer adsorbed on the surface of MoS2, and an acetonitrile molecular layer covering the outside of the aqueous micro-interface layer.

3. The method for preparing the MoS2-COF composite photothermal material according to claim 1, characterized in that, The volume ratio of water in the acetonitrile-water solvent system is 0.5%.

4. The method for preparing the MoS2-COF composite photothermal material according to claim 1, characterized in that, The mass ratio of MoS2 to COF in the MoS2 aqueous dispersion is 1:(0.1~10).

5. The method for preparing the MoS2-COF composite photothermal material according to claim 4, characterized in that, The mass ratio of MoS2 to COF in the MoS2 aqueous dispersion is 1:

1.

6. The method for preparing the MoS2-COF composite photothermal material according to claim 1, characterized in that, COF monomers include amino functional monomers and aldehyde functional monomers.

7. A MoS2-COF composite photothermal material, characterized in that, The MoS2-COF composite photothermal material is prepared according to any one of claims 1 to 6, comprising MoS2 and a COF layer confined and grown on MoS2.

8. The MoS2-COF composite photothermal material according to claim 7, characterized in that, The thickness of the COF layer on the MoS2-COF composite photothermal material is 1~10 nm.

9. The MoS2-COF composite photothermal material according to claim 7, characterized in that, The photothermal temperature of the MoS2-COF composite photothermal material is increased to 109.8 ℃, and the visible light-near infrared reflectivity is as low as 4.6%.

10. A MoS2-COF composite photothermal material according to claim 7, characterized in that, It is applied in the field of photothermal conversion.

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