A mixed solvent dispersion method for MoS2 nanosheets based on interface adsorption layer regulation

Abstract

The application provides a MoS2 nanosheet mixed solvent dispersion method regulated by an interface adsorption layer, comprising the following steps: MoS2 nanosheets are added into a first solvent for ultrasonic dispersion to obtain a pre-dispersion liquid; a second solvent is added into the pre-dispersion liquid for continuous ultrasonic dispersion to obtain a mixed system, wherein the mixed system contains 0.1% to 20% of the first solvent; the traditional technology only relies on the macroscopic matching of the solvent and the surface free energy of the MoS2 nanosheets, the stable adsorption layer is constructed on the surface of the MoS2 nanosheets, the interface interaction between the nanosheets and the mixed solvent is fundamentally reconstructed, the theoretical limitation of the single solvent dispersion is broken, and the stable dispersion of the MoS2 nanosheets in the mixed solvent is realized.

Description

Technical Field

[0001] This invention relates to the field of interface regulation and liquid-phase dispersion technology of two-dimensional nanomaterials, specifically to a method for dispersing MoS2 nanosheets in mixed solvents by means of an interface adsorption layer, and more specifically, to a method for achieving stable dispersion of MoS2 nanosheets in mixed solvents by means of an interface adsorption / solventization layer. Background Technology

[0002] As a typical two-dimensional layered nanomaterial, the excellent optical, electrical, catalytic, and mechanical properties of MoS2 nanosheets all depend on the single / few-layer nanosheet structure and uniform dispersion. Undispersed MoS2 will lose its nanoscale characteristics due to the aggregation of layers and will not be able to exert the intrinsic properties of the material. Therefore, before further processing and application of MoS2 nanosheets in industry, it is often necessary to achieve its efficient and stable dispersion first.

[0003] However, current methods for dispersing MoS2 nanosheets primarily rely on the macroscopic matching of the solvent and the surface free energy of the MoS2 nanosheets. This leads to the common practice of using only a single solvent for dispersing MoS2 nanosheets. In other words, the conventional approach is to select a single solvent that matches the surface free energy of the MoS2 nanosheets, relying on the thermodynamic compatibility of their interfacial energies to achieve temporary dispersion of the MoS2 nanosheets. Limited by this dispersion logic, there are few reports and studies on the dispersion of MoS2 nanosheets in mixed solvents.

[0004] Specifically, since the dispersion logic of existing technologies relies on the matching of the macroscopic surface free energy of the solvent bulk with the surface energy of MoS2 nanosheets to achieve dispersion, once the overall surface free energy of the mixed solvent deviates from this matching range (e.g., H2O-ACN is only 30.0 mJ / m², AA-CYH is only 27.0 mJ / m²), a stable thermodynamic basis for dispersion cannot be formed, directly leading to agglomeration and sedimentation. Moreover, mixed solvents exhibit solvent synergy, molecular adsorption, and interface reconstruction, and multi-component molecules will interact (e.g., weak binding between polar and non-polar solvent molecules), changing the original interfacial interaction characteristics of a single solvent. However, existing technologies have not studied and utilized this characteristic, and still treat mixed systems with the dispersion approach of a single solvent, resulting in uncontrollable dispersion behavior.

[0005] In summary, there is an urgent need to overcome the inherent limitations of the single-solvent surface energy matching theory and develop a simple, mild, and quantifiable method for dispersing MoS2 nanosheets in mixed solvents. Summary of the Invention

[0006] The purpose of this invention is to provide a method for dispersing MoS2 nanosheets in mixed solvents by regulating the interfacial adsorption layer, thereby achieving stable dispersion of MoS2 nanosheets in mixed solvents.

[0007] This approach abandons the traditional approach that relies solely on surface free energy matching. Instead, it establishes an interface layer-induced dispersion model and constructs a stable interfacial adsorption layer on MoS2 nanosheets through sequential operations. This fundamentally reconstructs the interfacial interaction between MoS2 nanosheets and the mixed solvent, thereby enabling the stable dispersion of MoS2 nanosheets in the mixed solvent.

[0008] Specifically, this scheme replaces macroscopic surface energy matching with interfacial adsorption layer regulation. Even though the overall surface free energy of the mixed solvent is much lower than that of the MoS2 nanosheets, as long as an interfacial adsorption layer is constructed on the surface of the MoS2 nanosheets, stable dispersion can be achieved through the polarity reconstruction, steric hindrance, and synergistic solvation of the interfacial adsorption layer, thus completely breaking through the limitations of traditional principles.

[0009] To achieve the above objectives, this technical solution provides a method for dispersing MoS2 nanosheets in a mixed solvent through interfacial adsorption layer control, comprising the following steps: A pre-dispersion liquid is obtained by ultrasonically dispersing monolayer MoS2 nanosheets or a few layers of MoS2 nanosheets in a first solvent, wherein the first solvent contains acrylic acid. A second solvent is added to the pre-dispersed liquid and ultrasonic dispersion is continued to obtain a mixed system, wherein the mixed system contains 0.1% to 20% of the first solvent.

[0010] This method pre-disperses MoS2 nanosheets in a first solvent, allowing acrylic acid to form a specific adsorption layer with the defect sites on the surface of the MoS2 nanosheets. Then, a second solvent is added so that the MoS2 nanosheets can form a synergistic solvation effect with the adsorption layer on the surface and the second solvent, achieving long-term stable dispersion in the mixed solvent system. The second solvent further forms an interface layer on the adsorption layer, and then utilizes the steric hindrance and interfacial polarity reconstruction effect of the interface layer and the adsorption layer to weaken the agglomeration driving force between the layers, thus overcoming the theoretical limitation of surface energy matching of a single solvent.

[0011] In other words, this solution provides an interface layer-induced dispersion model for the dispersion of MoS2 nanosheets. This interface layer-induced dispersion model first disperses MoS2 nanosheets in a first solvent to form a stable adsorption layer on the surface of the MoS2 nanosheets. At this time, the interfacial energy structure, steric hindrance, and intermolecular interaction mode of the MoS2 nanosheets are all changed, which significantly affects the interlayer interaction potential energy of the subsequent dispersion in the second solvent, thereby overcoming the defect that MoS2 nanosheets cannot be dispersed in the second solvent or mixed solvent.

[0012] Preferably, the Mo atoms at the defect sites on the acrylic acid and MoS2 nanosheets form coordination / hydrogen bonds, resulting in a stable monomolecular adsorption layer with an adsorption density of 2-3 molecules / nm². That is, an adsorption layer formed of acrylic acid is formed on the surface of the MoS2 nanosheets in the pre-dispersion solution.

[0013] Preferably, the first solvent contains 1% acrylic acid.

[0014] Preferably, the first solvent contains water, which forms an adsorption layer on the surface of the MoS2 nanosheets, thus achieving interfacial polarity reconstruction and steric hindrance.

[0015] Preferably, the thickness of the adsorption layer is 0.5~1.5 nm.

[0016] More preferably, the thickness of the adsorption layer is 1 nm.

[0017] Preferably, the first solvent contains 1% water.

[0018] Preferably, the first solvent further contains ethanol and N-methylpyrrolidone.

[0019] When the first solvent contains ethanol, ethanol serves two purposes: firstly, it acts as an adsorption layer; secondly, it can modulate the surface free energy of the mixed solvent, resulting in better matching of the molybdenum disulfide nanosheets. Of course, besides ethanol, ethylene glycol (EG) and 1,4-butanediol (BDO) also have some dispersing effects.

[0020] Preferably, the dispersion concentration of MoS2 nanosheets in the first solvent is 0.1~60 g / L.

[0021] Preferably, MoS2 nanosheets are added to a first solvent and ultrasonically dispersed for 5-30 min to obtain a pre-dispersion. More preferably, MoS2 nanosheets are added to a first solvent and ultrasonically dispersed for 10 min to obtain a pre-dispersion.

[0022] In some embodiments, the second solvent of this scheme has no strongly polar functional groups and can form intermolecular affinity with the outer side of the hydrocarbon chain portion of the adsorption layer to maintain the dispersion stability of MoS2 nanosheets in the mixed solvent. Of course, the second solvent of this scheme may also contain polar functional groups, that is, this scheme does not particularly limit the polarity of the second solvent.

[0023] Preferably, the second solvent includes any one or a combination of cyclohexane, dichloromethane, tetrahydrofuran, toluene, n-hexane, and petroleum ether.

[0024] Preferably, a second solvent is added to the pre-dispersed liquid and ultrasonic dispersion is continued to obtain a mixed system.

[0025] Preferably, the ratio of the second solvent to the first solvent is (99.9~80):(0.1~20).

[0026] Preferably, a second solvent is added to the pre-dispersion liquid and ultrasonic dispersion is continued until there are no obvious sedimented particles and the Tyndall effect is observed to obtain a mixed system.

[0027] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects: This invention innovatively proposes an interface layer-induced dispersion model, abandoning the traditional approach that relies solely on the macroscopic matching of the surface free energy of the solvent and MoS2 nanosheets. By constructing a stable acrylic acid monomolecular adsorption layer or a water solvation layer on the surface of MoS2 nanosheets, the interfacial interaction between the nanosheets and the mixed solvent is fundamentally reconstructed. This breaks through the theoretical limitations of single-solvent dispersion. Even if the overall surface free energy of the mixed solvent is much lower than that of the MoS2 nanosheets, long-term stable dispersion in the mixed solvent can still be achieved. It also successfully solves the technical problem of the inability of MoS2 nanosheets to be stably dispersed in traditional non-polar and difficult-to-disperse solvents such as cyclohexane and dichloromethane, greatly expanding the solvent application range and industrial application adaptability of MoS2 nanosheets.

[0028] This invention clarifies the regulatory mechanism of small molecule adsorption / water solvation layer on the interfacial structure and dispersion stability of MoS2 nanosheets, transforming the dispersion behavior from an uncontrollable state that traditionally depends on the bulk properties of the solvent to a state that can be quantitatively controlled by parameters such as adsorption density, solvation layer thickness, and polar component ratio. Furthermore, the dispersion process can be accurately characterized and verified by Freundlich model, TGA, XPS, and other methods, and the dispersion results are stable and reproducible, providing a new theoretical basis and technical reference for the dispersion regulation of two-dimensional nanomaterials.

[0029] The dispersion process of this invention is carried out entirely at room temperature, without the need for harsh reaction conditions or special equipment. The MoS2 nanosheets and various polar / non-polar solvents used are all conventional commercially available products in the prior art. The raw materials are widely available and low in cost. The solvent selection range is large and the combination is flexible. It can be customized according to different industrial needs, and has the advantages of convenient operation, potential for large-scale application and adaptability to different scenarios. At the same time, the prepared dispersion system shows no obvious agglomeration and sedimentation after standing at room temperature for more than 72 hours, and its stability is far superior to the existing single solvent dispersion technology. Attached Figure Description

[0030] Figure 1 This is a schematic diagram showing the dispersion of MoS2 nanosheets in a single solvent.

[0031] Figure 2 This is a schematic diagram showing the dispersion of MoS2 nanosheets in a mixed solvent.

[0032] Figure 3This is a schematic diagram showing the results of studying the effect of solvent addition order on dispersion.

[0033] Figure 4 It is an adsorption isotherm diagram.

[0034] Figure 5 This is a comparison chart of TGA thermogravimetric analysis.

[0035] Figure 6 These are contact angle and surface free energy test results.

[0036] Figure 7 This is an XPS test graph. Detailed Implementation

[0037] 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.

[0038] Example 1: Dispersion of a single solvent: 0.2 mg of MoS2 nanosheets were added to 10 mL of different single solvents, including water (H2O), ethanol (EtOH), N-methylpyrrolidone (NMP), 1,4-butanediol (BDO), acrylic acid (AA), acetonitrile (ACN), toluene (Tol), tetrahydrofuran (THF), cyclohexane (CYH), and dichloromethane (DCM). After sonication for 10 min, the dispersion was observed and photographed. The results are shown below. Figure 1 As shown, MoS2 nanosheets can be dispersed in solvents such as H2O, EtOH, NMP, AA, and ACN, but cannot be dispersed in Tol, THF, CYH, and DCM. After 12 hours of dispersion in EtOH, AA, and ACN, the nanosheets still show significant sedimentation, failing to provide a long-term stable dispersion environment for MoS2. The fundamental reason for this is that the interfacial interaction between the above single solvents and the MoS2 surface is insufficient, making it difficult to effectively overcome the van der Waals stacking forces between the layers and achieve stable dispersion.

[0039] Example 2, Dispersion of mixed solvents: Using the first and second solvents as a mixed solvent, 0.2 mg of MoS2 nanosheets were dispersed in 0.1 mL of the first solvent and sonicated for 10 min to form a pre-dispersion. Then, 9.9 mL of the second solvent was added and sonicated for another 10 minutes at a power of 30 W / L, or until no sedimentation particles were visible and the Tyndall effect was observed. The dispersion was then observed and photographed. The results are shown below. Figure 2 As shown, the dispersion stability of the ETOH-H2O and H2O-ACN systems is significantly improved. Furthermore, after mixing AA-CYH, NMP-DCM, and ETOH-THF, the system transforms from an originally non-dispersible state to a dispersible state, while forming an emulsion state in EG-TOL. It is evident that, except for the ETOH-H2O system, which has been studied to optimize dispersion by adjusting the solvent surface free energy, the surface free energy of the other solvent mixtures is relatively low, and the principle of "solvent-nanosheet surface free energy matching" no longer applies. This indicates that in these systems, the dispersion behavior of nanosheets may be affected by the formation of an adsorption layer on the surface by the solvent.

[0040] The surface free energies of the compound solvents are shown in Table 1 below: Table 1 Surface Free Energy of Different Mixed Solvents .

[0041] Example 3 investigates the effect of solvent addition order on dispersion. To elucidate the fundamental reasons for the differences in the dispersion behavior of MoS2 nanosheets in different compound solvent systems, this study first used the AA-CYH system as a model to explore the influence of the surface adsorption layer on the interfacial structure and dispersion stability.

[0042] Experimental Procedure: 0.2 mg of MoS2 nanosheets were dispersed in 0.1 mL of acrylic acid and sonicated for 10 min to form a pre-dispersion. Then, 9.9 mL of CYH was added and sonicated for 10 minutes (30 W / L) or until no sedimentation particles were visible and the Tyndall effect was observed. The dispersion was then observed and photographed. Alternatively, 0.1 mL of acrylic acid and 9.9 mL of CYH were mixed to obtain a mixture. 0.2 mg of MoS2 nanosheets were added to this mixture and sonicated. The dispersion was then observed and photographed. The results are shown in the figures below. Figure 3 As shown.

[0043] It is evident that when MoS2 nanosheets are first fully dispersed in AA and then slowly added to CYH, a homogeneous dispersion system can be formed. In contrast, if AA and CYH solvents are mixed uniformly first and then MoS2 is added, the nanosheets remain undispersible, exhibiting a clear dispersion order dependence. This suggests that the dispersion behavior of MoS2 nanosheets in mixed solvents is not determined by a single solvent polarity or surface free energy, but rather involves a dynamic reconstruction process of the nanosheet surface interfacial structure. When MoS2 is first dispersed in AA, AA molecules have sufficient contact time to form specific adsorption at the defect sites on the MoS2 surface, constructing a monomolecular interfacial adsorption layer, thereby improving interfacial compatibility. The subsequent addition of CYH solvent can form a synergistic solvation effect with the surface-adsorbed AA molecules, maintaining stable dispersion of the nanosheets. Conversely, if AA and CYH are mixed in advance, AA molecules preferentially form weak intermolecular interactions with CYH, reducing their adsorption activity and decreasing their binding efficiency with the MoS2 surface, failing to effectively form an adsorption layer, leading to aggregation and sedimentation. Therefore, the formation of the interfacial adsorption layer is the key mechanism for achieving stable dispersion of MoS2 in mixed solvents.

[0044] Example 4: Adsorption isotherm test: Experimental procedure: AA-CYH solutions with different volume fractions (concentration range 0.1%-20.0%) were prepared, and 0.5 mg of MoS2 nanosheets were added to them. The solutions were shaken and adsorbed at 25 °C for 6 h to reach adsorption equilibrium. The solid and liquid phases were then separated by centrifugation (5000 rpm, 10 min). The supernatant was taken and the UV absorption intensity was measured. The equilibrium concentration Ce was calculated based on the standard curve.

[0045] The adsorption capacity Qe is calculated using the following formula:

[0046] Where C0 is the initial concentration, V is the solution volume, and m is the mass of MoS2.

[0047] The adsorption data were fitted using the Freundlich model:

[0048] K was obtained through fitting f And the value of n.

[0049] Draw an adsorption isotherm based on the change in AA concentration before and after adsorption, as shown below. Figure 4 As shown, the adsorption process of AA molecules on the MoS2 surface conforms to the Freundlich adsorption model, and the correlation coefficient R obtained from the fitting is... 2A value greater than 0.99 indicates that the adsorption process is a non-ideal multi-site adsorption. The Freundlich model is applicable to the adsorption process on heterogeneous surfaces, and its good fitting effect confirms that there are a large number of different types of adsorption sites on the MoS2 surface. The adsorption energies of AA molecules at these adsorption sites vary, and the adsorption process may be accompanied by multilayer adsorption of AA molecules and intermolecular synergistic effects.

[0050] Furthermore, by accurately calculating the adsorption amount and combining it with the surface area of ​​MoS2 nanosheets, the adsorption density of AA on the MoS2 surface was calculated to be approximately 2–3 molecules / nm. 2 This value is within a reasonable range, further illustrating the orderliness and stability of the adsorption. The applicability of the Freundlich model further confirms the non-uniformity of the MoS2 surface, which is consistent with the intrinsic characteristics of different types of active sites such as defect sites and edge sites on the surface of MoS2 nanosheets. The method for calculating the actual adsorption amount of AA is as follows: the MoS2 sample after AA adsorption is centrifuged, washed, and vacuum dried. Under a nitrogen atmosphere, the temperature is increased from room temperature to 600 ℃ at a rate of 10 ℃ / min. The actual adsorption amount of AA is calculated through mass loss and converted into molecules per unit area (molecules / nm). 2 ).

[0051] Example 5, Thermogravimetric Analysis: To further verify the existence of the interfacial adsorption layer, 0.2 mg of MoS2 nanosheets were dispersed in 0.1 mL of AA and sonicated for 10 min to form a pre-dispersion. Then, 9.9 mL of CYH was added and sonicated again (30 W / L, for 10 min, or until no sedimentation particles were visible and the Tyndall effect was observed). Adsorption was carried out at 25 °C for 6 h to reach adsorption equilibrium. After the adsorption experiment, the sample was washed three times with CYH to remove free unadsorbed AA molecules and then vacuum dried at room temperature. Pure MoS2 nanosheets were used as the pure MoS2 sample, and the dried sample was used as the MoS2-AA sample. Thermogravimetric analysis (TGA) was performed on both the pure MoS2 and MoS2-AA samples, and the results are shown below. Figure 5 As shown.

[0052] TGA analysis showed that the MoS2-AA sample with adsorbed AA exhibited a significant mass loss step around 240 °C, while the mass change of the pure MoS2 sample was relatively insignificant in this temperature range. This indicates that the mass loss can be attributed to the thermal decomposition of AA molecules adsorbed on the MoS2 surface. By accurately calculating the mass loss rate in this temperature range and combining it with the mass of MoS2 in the sample, the actual adsorption capacity of AA on the MoS2 surface can be estimated to be approximately 2–3 molecules / nm. 2The results are highly consistent with the calculation results of the Freundlich model, which further confirms that AA forms a stable monomolecular adsorption layer on the MoS2 surface, providing a solid experimental basis for subsequent mixed solvent dispersion and interface functionalization. Example 6: Contact Angle and Surface Free Energy Tests: Experimental procedure: Contact angles of water, EG, NMP, EtOH, and IPA were measured, and surface free energy was calculated based on the OWRK method. Figure 6 As shown, the results indicate that the surface free energy of MoS2 is 48.7 mJ / m 2 Increased to 57.7 mJ / m 2 This result indicates that AA adsorption significantly alters the surface energy structure and interfacial properties of the material.

[0053] From the perspective of molecular interaction mechanisms, AA molecules anchor to surface defect sites of MoS2 through their carboxyl groups, forming a stable interfacial adsorption layer. The hydrocarbon chains are arranged outwards, constructing an organic shell on the material surface. This shell increases the intermolecular cohesive energy, leading to an increase in surface free energy. Simultaneously, the exposed hydrocarbon chains enhance interfacial compatibility with the second solvent, CYH. Furthermore, the adsorption layer provides steric hindrance between the layers, reducing the direct contact area and weakening the van der Waals force-driven secondary stacking tendency. Therefore, AA-pretreated MoS2 can achieve stable dispersion in CYH. These results indicate that the dispersion behavior of the material is not solely determined by solvent surface tension matching, but is closely related to the formation of a stable interfacial layer.

[0054] Example 7, XPS Test: Experimental procedure: X-ray photoelectron spectroscopy (XPS) analysis: XPS spectra were recorded using a 250Xi spectrometer (Thermo Fisher, USA), and the peak position was calibrated with the C 1s peak (284.6 eV).

[0055] Experimental results are as follows Figure 7 As shown, XPS analysis further verified the adsorption and interaction mechanism of AA on the MoS2 surface. In the C 1s spectrum ( Figure 6 In (a), the MoS2 sample after AA adsorption showed new characteristic peaks, corresponding to the C=O bond (binding energy approximately 288.50 eV) and CO bond (binding energy approximately 286.25 eV) of the carboxyl group in the AA molecule, respectively, indicating that the AA molecules had been successfully adsorbed onto the MoS2 surface; in the O 1s spectrum ( Figure 6 In (b), the characteristic peak intensities of the adsorbed sample near 531.96 eV and 533.30 eV are significantly enhanced, corresponding to oxygen atoms in the carboxyl group, further confirming the adsorption of AA molecules on the MoS2 surface; simultaneously, in the Mo 3d spectrum ( Figure 6In (c), the peak positions of Mo 3d5 / 2 and Mo 3d3 / 2 show a slight shift (the shift is about 0.2 eV), indicating that there is a weak interaction (such as coordination or hydrogen bonding) between the Mo atoms on the MoS2 surface and the carboxyl groups in the AA molecule. This interaction mainly occurs at the defect sites on the MoS2 surface, which is consistent with the fitting results of the previous Freundlich model.

[0056] Example 8: Testing the thickness of the solvation layer on MoS2 nanosheets: Using Carl The Fischer coulometric titrator was used to determine trace amounts of water, obtaining the change in water content in the bulk solution before and after adsorption. The volume of water adsorbed on the surface of the MoS2 nanosheets was calculated by subtracting the water content before adsorption from the water content after adsorption. Combined with the specific surface area of ​​the MoS2 nanosheets, the thickness of the solvation layer was obtained by dividing the volume of adsorbed water by the adsorption surface area.

[0057] 0.2 mg of MoS2 nanosheets were dispersed in 0.1 mL of H2O and sonicated for 10 min to form a pre-dispersion. Then, 9.9 mL of acetonitrile was added and sonicated for 10 min (30 W / L, or until no sedimentation particles were visible and the Tyndall effect was observed). The mixture was then shaken and adsorbed at 25 °C for 6 h to reach adsorption equilibrium.

[0058] This study further investigates the H2O-ACN mixed solvent system. Previous research has shown that when the volume fraction of H2O is below 20%, the surface free energy of the H2O-ACN composite solvent is less than 30 mJ / m². 2 The efficiency is significantly lower than that of MoS2 nanosheets (48.7 mJ / m). 2 It is difficult for the two to achieve interfacial energy matching; only when the water content increases to over 65% can the surface free energy of the mixed solvent approach that is favorable to MoS2. 2 The system exhibits a stable dispersion within a certain range. Therefore, from the perspective of macroscopic surface free energy matching, the system only possesses a good dispersion thermodynamic basis under conditions of high water content.

[0059] However, experimental results show that even under extremely low water content conditions (e.g., 0.5%), the dispersion stability of the system can be significantly improved. This phenomenon indicates that the dispersion behavior is not entirely controlled by the macroscopic solvent surface free energy, but may involve an interfacial adsorption layer regulation mechanism. Moisture measurement results show that when the H2O volume fraction is 0.5%, a water adsorption layer of approximately 1 nm thickness can be formed on the surface of MoS2 nanosheets. This thickness is significantly higher than the scale of a monomolecular water layer, indicating that water molecules form a stable solvation layer structure on the MoS2 surface through a hydrogen bond network, rather than a simple monolayer adsorption. Although this solvation layer differs from the organic anchoring layer formed by AA, it has a similar function in interfacial regulation. First, the hydrogen bond network formed by water molecules on the surface alters the interfacial polarity structure; second, the solvation layer forms physical isolation between the sheets, reducing the probability of direct contact; third, the presence of the interfacial adsorption layer reconstructs the effective interfacial energy state between MoS2 and ACN, making the local interfacial environment different from the macroscopic surface free energy parameters of the bulk solvent. Therefore, even when the overall solvent surface free energy has not yet reached the matching range, as long as a stable interfacial adsorption layer is formed, the driving force for interlayer aggregation can still be significantly weakened, and the dispersion stability can be improved.

[0060] 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.

[0061] 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 dispersing MoS2 nanosheets in a mixed solvent through an interfacial adsorption layer, characterized in that, Includes the following steps: A pre-dispersion liquid is obtained by ultrasonically dispersing monolayer MoS2 nanosheets or a few layers of MoS2 nanosheets in a first solvent, wherein the first solvent contains acrylic acid. A second solvent is added to the pre-dispersed liquid and ultrasonic dispersion is continued to obtain a mixed system, wherein the mixed system contains 0.1% to 20% of the first solvent.

2. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer as described in claim 1, characterized in that, An adsorption layer is formed on the surface of MoS2 nanosheets in the pre-dispersion liquid, wherein the adsorption layer is formed by coordination / hydrogen bonding of acrylic acid and Mo atoms at defect sites on the MoS2 nanosheets.

3. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer as described in claim 2, characterized in that, The adsorption density of the adsorption layer is 2~3 molecules / nm².

4. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer according to claim 1, characterized in that, The first solvent contains water, and the adsorption layer is formed by water adsorbed onto the defect sites and surface of MoS2 nanosheets through a hydrogen bond network.

5. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer according to claim 4, characterized in that, The thickness of the adsorption layer is 0.5~1.5nm.

6. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer according to claim 1, characterized in that, The first solvent contains ethanol, N-methylpyrrolidone, or any combination thereof.

7. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer according to claim 1, characterized in that, The second solvent includes any one or a combination of cyclohexane, dichloromethane, tetrahydrofuran, toluene, n-hexane, and petroleum ether.

8. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer according to claim 1, characterized in that, The ratio of the second solvent to the first solvent is (99.9~80):(0.1~20).

9. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer according to claim 1, characterized in that, The first solvent contains 1% acrylic acid.

10. The method for dispersing MoS2 nanosheets in a mixed solvent by means of an interfacial adsorption layer according to claim 1, characterized in that, The first solvent contains 1% water.

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