Preparation method and application of full-spectrum light absorption two-dimensional molybdenite (MoS2) composite material

Abstract

The invention provides a preparation method and application of a full-spectrum light absorption two-dimensional molybdenite (MoS2) composite material. The size and distribution of Pd clusters are regulated and controlled through PVP, the average particle size of the Pd clusters is 8.18 + / -2.08 nm, the light absorption capacity of the material in a full spectrum, especially in a near-infrared de-region is enhanced, and the problems that according to a traditional compounding method, uniform dispersion of metal nanoparticles is difficult to achieve, the photo-thermal performance is unstable, and the photo-thermal conversion efficiency is not remarkably improved are solved; the photo-thermal performance of the MoS2-Pd composite material is remarkably improved by regulating and controlling the particle size of the Pd clusters, the LSPR effect of the material is remarkably enhanced through uniform Pd cluster distribution, and particularly, the light absorption capacity in a near-infrared region is improved by 30%-60%. The full-spectrum light absorption two-dimensional molybdenite composite material disclosed by the invention has excellent cycling stability, water purification performance and thermal management capability, and is suitable for practical solar desalination application.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermal conversion materials, and in particular to a preparation method and application of a full-spectrum light-absorbing two-dimensional molybdenite composite material. Background Art

[0002] In the context of the increasing global water shortage, the development of efficient water treatment and purification technologies has become an urgent need. Solar-driven interfacial evaporation technology is a sustainable and environmentally friendly solution that uses solar energy to evaporate water. The technology relies on efficient photothermal conversion materials to maximize the utilization of solar energy.

[0003] MoS 2 Due to its unique two-dimensional structure and excellent optical and electrical properties, it has become the focus of researchers. 2 It has good light absorption ability in the visible light range, but weak absorption in the near-infrared region, which limits its overall photothermal conversion efficiency. 2 The ability to absorb light in the near-infrared region is the key to improving its performance.

[0004] A common approach is to combine MoS2 with organic compounds that can broadly absorb near-infrared light. However, the lack of functional groups on its surface makes MoS2 difficult to absorb. 2 The effective combination with organic materials brings challenges, thus limiting its application. In contrast, noble metals can effectively combine with MoS while showing good near-infrared light absorption and photothermal conversion performance. 2 Combining and changing its band structure significantly improves the material's light absorption ability in the near-infrared region. 2 The composite process with Pd faces some technical obstacles, such as the Pd clusters in MoS 2 The uneven surface distribution and the difficulty in controlling the size of clusters have resulted in limited improvements in photothermal performance and hampered the effectiveness of the material in practical applications.

[0005] Based on the current MoS 2 There are defects in photothermal conversion materials, and it is necessary to improve them. Summary of the invention

[0006] In view of this, the present invention provides a full-spectrum light-absorbing two-dimensional molybdenite composite material and a preparation method and application thereof to solve the defects existing in the prior art.

[0007] In a first aspect, the present invention provides a method for preparing a full-spectrum light-absorbing two-dimensional molybdenite composite material, comprising the following steps: MoS 2 MoS nanosheets and Pd clusters are combined to obtain 2-Pd composite materials; MoS 2 The nanosheets were mixed with polytetrafluoroethylene and coated on non-woven fabrics and dried to obtain MoS 2 Photothermal materials; MoS 2 The -Pd composite material is mixed with polytetrafluoroethylene, coated on a non-woven fabric and dried to obtain a full-spectrum light-absorbing two-dimensional molybdenite composite material.

[0008] Preferably, the MoS 2 The method for preparing the nanosheets comprises the following steps: Using the molybdenite sheet as a cathode, placing the cathode and the anode in an electrolyte and connecting them to a power source for electrolysis to obtain an expanded molybdenite sheet; Grinding the expanded molybdenite flakes to obtain an exfoliation product; The exfoliated product was ultrasonicated and centrifuged to obtain MoS 2 Nanosheets; The process parameters of electrochemical stripping control are: the electrolyte is 0.5~0.8 mol / L NaOH solution, the current density is 0.02~0.03A / cm 2 The electrolytic stripping time is 10~12h.

[0009] Preferably, MoS 2 MoS nanosheets and Pd clusters are combined to obtain 2 -Pd composite materials, specifically including: MoS 2 The nanosheets were dispersed in DMF and then added with PdCl 2 The precursor solution was subjected to hydrothermal reaction, filtered, washed and dried to obtain MoS 2 -Pd composite material.

[0010] Preferably, the hydrothermal reaction temperature is 140-150° C. and the time is 6-10 h.

[0011] Preferably, the PdCl 2 The precursor solution includes: palladium chloride, hydrochloric acid, polyvinyl pyrrolidone; The molar ratio of palladium chloride, hydrochloric acid and polyvinyl pyrrolidone is (1-2):(1-3):(1-2).

[0012] Preferably, the PdCl 2 The precursor solution of PdCl 2 The concentration is 1~2mg / mL.

[0013] Preferably, the MoS 2 Nanosheets, DMF, containing PdCl 2The mass volume ratio of the precursor solution is (150~160) mg: (150~160) mL: (1~2) mL; and / or, MoS 2 Nanosheets, polytetrafluoroethylene, and ethanol were mixed and coated on non-woven fabrics and dried to obtain MoS 2 Photothermal materials; MoS 2 -Pd composite material, polytetrafluoroethylene and ethanol are mixed, coated on non-woven fabric and dried to obtain a full-spectrum light-absorbing two-dimensional molybdenite composite material; Among them, MoS 2 -The mass volume ratio of Pd composite material, polytetrafluoroethylene, and ethanol is (20~30) mg: (1~2) mL: (5~10) mL; And / or, the exfoliation product is ultrasonicated and centrifuged to obtain MoS 2 In the nanosheet step, the centrifugal speed is 6000-8000 rpm and the centrifugal time is 20-30 min.

[0014] Preferably, the nonwoven fabric is a blend of cotton and polypropylene fibers.

[0015] In a second aspect, the present invention also provides a full-spectrum light-absorbing two-dimensional molybdenite composite material, which is prepared by the preparation method.

[0016] In a third aspect, the present invention also provides a full-spectrum light-absorbing two-dimensional molybdenite composite material as a solar-driven interface evaporation material for seawater desalination or high-salt wastewater treatment.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The preparation method of the full-spectrum light-absorbing two-dimensional molybdenite composite material of the present invention regulates the size and distribution of Pd clusters by PVP, and the average particle size of the Pd clusters is 8.18±2.08 nm, which enhances the light absorption capacity of the material in the full spectrum, especially in the near-infrared. The problem that the traditional composite method (such as physical mixing) is difficult to achieve uniform dispersion of metal nanoparticles, which easily leads to unstable photothermal performance, and the photothermal conversion efficiency is not significantly improved, and the evaporation rate decreases after cyclic use is solved. The full-spectrum light-absorbing two-dimensional molybdenite composite material still maintains a very stable evaporation rate after 10 cycles of use, and the evaporation rate increases from 1.206 kg·m -2 ·h -1 (about 1.21 kg·m -2 ·h -1 ) becomes 1.192 kg·m -2 ·h -1 ; The present invention significantly improves the MoS by regulating the particle size of Pd clusters. 2The photothermal performance of the -Pd composite material is specifically reflected in the following: By adding PVP as a surfactant, the average particle size of the Pd clusters is successfully controlled to 8.18±2.08 nm, and the particle size distribution range is narrow. The uniform distribution of Pd clusters significantly enhances the LSPR effect of the material, especially in the near-infrared region (1000-2500 nm), the light absorption capacity is increased by 30%-60%, thereby achieving the effect of full-spectrum light absorption.

[0018] 2. The full-spectrum light-absorbing two-dimensional molybdenite composite material prepared by the present invention has excellent economic benefits and performance. 2 The evaporation rate of the nanosheets is 1.053 kg·m -2 ·h -1 , the light-to-heat conversion efficiency is 74.21%. MoS 2 The evaporation rate of -Pd is 1.206 kg·m -2 ·h -1 The photothermal conversion efficiency is 85.03%. The full-spectrum light-absorbing two-dimensional molybdenite composite material still maintains a very stable evaporation rate after 10 cycles. The evaporation rate after 10 cycles is 1.192 kg·m -2 ·h -1 , in the treated seawater, Na + Mg 2+ , K + and Ca 2+ The concentration of major ions is significantly reduced, at least by three orders of magnitude, which meets the WHO drinking water standard; the surface temperature distribution of the full-spectrum light-absorbing two-dimensional molybdenite composite material is uniform and the central heat is concentrated, and it has a fast response capability during the light-heat conversion process. The full-spectrum light-absorbing two-dimensional molybdenite composite material of the present invention has excellent cycle stability, water purification performance, and thermal management capabilities, and is suitable for practical solar desalination applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a physical picture of the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1; Figure 2 A diagram of a photothermal evaporation device assembled with the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1; Figure 3is an optical microscope image of the nonwoven fabric used in Example 1; Figure 4 This is an optical microscope image of the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1; Figure 5 is MoS in Example 1 2 TEM images of the composite materials; Figure 6 The MoS prepared in step S2 of Example 1 2 -TEM image of Pd composite material; Figure 7 The MoS prepared in step S2 of Example 1 2 -Pd composite material and MoS in step S1 2 XRD pattern of nanosheets; Figure 8 The MoS prepared in step S2 of Example 1 2 -XPS graph of Pd composite material; Fig. 9 The mass loss curves of seawater under 1 sun intensity for different photothermal materials in Example 1 and Comparative Example 1; Fig.10 is the evaporation rate of seawater under 1 sun intensity for different photothermal materials in Example 1 and Comparative Example 1; Fig.11 is the photothermal conversion efficiency of the full-spectrum light-absorbing two-dimensional molybdenite composite material under 1 sun intensity for different photothermal materials in Example 1 and Comparative Example 1; Fig.12 The MoS prepared in step S2 of Example 1 2 -Pd composite material and MoS in step S1 2 UV-visible diffuse reflectance image of nanosheets; Fig.13 The changes of various ions in the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1 before and after evaporation of Bohai Sea water; Fig.14 This is a graph showing the change in water evaporation rate of seawater after different photothermal materials are used in Example 1 and Comparative Example 1 for different cycles. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0023] The present application provides a full-spectrum light-absorbing two-dimensional molybdenite (MoS 2 ) A method for preparing a composite material, comprising the following steps: S1, MoS 2 MoS nanosheets and Pd clusters are combined to obtain 2 -Pd composite materials; S2, MoS 2 The nanosheets were mixed with polytetrafluoroethylene and coated on non-woven fabrics and dried to obtain MoS 2 Photothermal materials; MoS 2 -Pd composite material is mixed with polytetrafluoroethylene and coated on non-woven fabric and dried to obtain full-spectrum light-absorbing MoS 2 -Pd composite photothermal material is a full-spectrum light-absorbing two-dimensional molybdenite composite material.

[0024] In some embodiments, MoS is obtained by electrochemically assisted liquid phase stripping from molybdenite. 2 The nanosheet specifically comprises the following steps: Using the molybdenite sheet as a cathode, placing the cathode and the anode in an electrolyte and connecting them to a power source for electrolysis to obtain an expanded molybdenite sheet; Grinding the expanded molybdenite flakes to obtain an exfoliation product; The exfoliated product was ultrasonicated and centrifuged to obtain MoS 2 Nanosheets; The process parameters of electrochemical stripping control are: the electrolyte is 0.5~0.8 mol / L NaOH solution (NaOH aqueous solution), the current density is 0.02~0.03A / cm 2 The electrolytic stripping time is 10~12h.

[0025] Specifically, a molybdenite sheet is used as a cathode, the cathode and the anode are placed in an electrolyte, the cathode and the anode are connected to the negative electrode and the positive electrode of a power source respectively, and the current is controlled to perform electrolysis. After electrolysis, the molybdenite sheet expands to obtain an expanded molybdenite sheet, and the expanded molybdenite sheet is ground and filtered to obtain a stripping product; the stripping product is added to DMF, ultrasonicated, and centrifuged to obtain MoS 2 Nanosheets; the anode is a platinum electrode, and molybdenite is a molybdenum disulfide (MoS 2 ).

[0026] In some embodiments, the length and width of the molybdenite sheet are both 1-2 cm, and the thickness is 1-2 mm.

[0027] In some embodiments, MoS 2 MoS nanosheets and Pd clusters are combined to obtain 2 -Pd composite materials, specifically including: MoS 2 The nanosheets were dispersed in DMF (dimethylformamide) and then added with PdCl 2 The precursor solution was subjected to hydrothermal reaction, filtration, washing, and freeze drying to obtain MoS 2 -Pd composite material.

[0028] Specifically, MoS 2 Nanosheets were dispersed in DMF and added with PdCl 2 The precursor solution of Pd was prepared by changing the concentration of the precursor solution. The Pd 2+ Reduced to Pd clusters; MoS was obtained by filtration, deionized water / ethanol washing and freeze drying. 2 -Pd composite material; DMF acts as both a reducing agent and a solvent, providing a good dispersion environment to reduce Pd 2+ .

[0029] In some embodiments, the hydrothermal reaction temperature is 140-150° C. and the reaction time is 6-10 h.

[0030] In some embodiments, the PdCl 2 The precursor solution includes: palladium chloride, hydrochloric acid, polyvinyl pyrrolidone; The molar ratio of palladium chloride, hydrochloric acid and polyvinyl pyrrolidone is (1~2):(1~3):(1~2).

[0031] In some embodiments, the PdCl 2 The precursor solution of PdCl 2 The concentration is 1~2mg / mL.

[0032] Specifically, PdCl 2, polyvinylpyrrolidone (PVP) is added to hydrochloric acid (i.e., hydrochloric acid solution) to obtain a solution containing PdCl 2 The precursor solution is prepared by using PVP to adjust the size and distribution of Pd clusters. The average particle size of Pd clusters is 8.18±2.08nm, which enhances the light absorption capacity of the material in the full spectrum, especially in the near-infrared. The problem that the traditional composite method (such as physical mixing) is difficult to achieve uniform dispersion of metal nanoparticles, which easily leads to unstable photothermal performance, and the photothermal conversion efficiency is not significantly improved. The evaporation rate drops by more than 20% after recycling is solved. The present invention significantly improves the MoS by adjusting the particle size of Pd clusters. 2 The photothermal performance of the -Pd composite material is specifically reflected in the following: By adding PVP as a surfactant, the average particle size of the Pd clusters was successfully controlled to 8.18±2.08 nm, and the particle size distribution range was narrow. The uniform distribution of Pd clusters significantly enhanced the LSPR (localized surface plasmon resonance) effect of the material, especially in the near-infrared region (1000-2500 nm), the light absorption capacity was increased by 30%-60%.

[0033] In some embodiments, MoS 2 Nanosheets, DMF, containing PdCl 2 The mass volume ratio of the precursor solution is (150~160) mg: (150~160) mL: (1~2) mL; In some embodiments, MoS 2 Nanosheets, polytetrafluoroethylene, and ethanol were mixed and coated on non-woven fabrics and dried to obtain MoS 2 Photothermal materials; MoS 2 -Pd composite material, polytetrafluoroethylene, and ethanol are mixed and coated on non-woven fabric and dried to obtain full-spectrum light-absorbing MoS 2 -Pd composite photothermal material, which is a full-spectrum light-absorbing two-dimensional molybdenite composite material; Among them, MoS 2 -The mass volume ratio of Pd composite material, polytetrafluoroethylene, and ethanol is (20~30) mg: (1~2) mL: (5~10) mL; MoS 2 The mass volume ratio of nanosheets, polytetrafluoroethylene and ethanol is (20~30) mg: (1~2) mL: (5~10) mL.

[0034] In some embodiments, the exfoliated product is sonicated and centrifuged to obtain MoS 2 In the nanosheet step, the centrifugal speed is 6000-8000 rpm and the centrifugal time is 20-30 min.

[0035] In some embodiments, the nonwoven fabric is blended from cotton and polypropylene fibers. Specifically, the mass ratio of cotton to polypropylene fibers is 7:3.

[0036] The preparation method of the full-spectrum light-absorbing two-dimensional molybdenite composite material of the present invention significantly improves the light absorption performance and photothermal conversion efficiency by optimizing the size, distribution and loading amount of palladium clusters, and is particularly suitable for solar-driven interfacial evaporation, seawater desalination, wastewater treatment and photothermal power generation. The core innovation of the present invention is to utilize the localized surface plasmon resonance (LSPR) effect to effectively enhance the light capture ability of the material in the near-infrared spectral region, and at the same time, to regulate the palladium clusters through surfactants to make them uniformly dispersed, thereby solving the problems of existing photothermal materials due to insufficient near-infrared absorption and reduced efficiency caused by agglomeration of metal nanoparticles. The present invention provides a new strategy for low-cost and high-efficiency solar interfacial evaporation technology.

[0037] Based on the same inventive concept, the present invention also provides a full-spectrum light-absorbing two-dimensional molybdenite composite material, which is prepared by the preparation method.

[0038] Based on the same inventive concept, the present invention also provides the above-mentioned full-spectrum light-absorbing two-dimensional molybdenite composite material as a solar-driven interface evaporation material for seawater desalination or high-salt wastewater treatment.

[0039] The following further illustrates the full-spectrum light-absorbing two-dimensional molybdenite composite material of the present application and its preparation method and application with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0040] The nonwoven fabrics used in the following examples and comparative examples are obtained by blending cotton and polypropylene fibers, and are provided by Kunshan Yichen Clean Materials Co., Ltd. The mass ratio of cotton to polypropylene fibers is 7:3.

[0041] Example 1 The present invention provides a full-spectrum light-absorbing two-dimensional molybdenite (MoS 2 ) A method for preparing a composite material, comprising the following steps: S1. A molybdenite sheet (the length and width of the molybdenite sheet are both 1 cm, and the thickness is 1 mm) is used as a cathode. The cathode and anode (the anode is graphite) are placed in an electrolyte and connected to a power supply for electrolysis to obtain an expanded molybdenite sheet. The expanded molybdenite sheet is ground to obtain a stripping product. The process parameters of the electrochemical stripping control are: the electrolyte is 0.5 mol / L NaOH solution, the current density is 0.02 A / cm 2, the electrolytic stripping time is 10h; The stripped product was added to DMF and ultrasonicated for 6 h, then centrifuged at 6000 rpm for 20 min and freeze-dried to obtain MoS 2 Nanosheets; S2. Add 150 mg MoS into the round bottom flask. 2 Nanosheets and 150 mL DMF were mixed evenly, and then 1 mL of PdCl 2 The precursor solution was reacted at 140 °C for 6 h. The product was filtered, washed with deionized water, and freeze-dried to obtain MoS 2 -Pd composite materials; containing PdCl 2 The precursor solution includes: palladium chloride, hydrochloric acid, and polyvinyl pyrrolidone; the molar ratio of palladium chloride, hydrochloric acid, and polyvinyl pyrrolidone is 1:2:1, and contains PdCl 2 The precursor solution of PdCl 2 The concentration is 1 mg / mL; S3, 20 mg MoS 2 -Pd composite material, 1 ml PTFE and 5 ml ethanol were mixed, and ultrasonicated for 30 min to make them dispersed evenly to obtain a dispersion; S4, the dispersion is evenly coated on the non-woven fabric, and the full-spectrum light-absorbing MoS is obtained after natural drying. 2 -Pd composite photothermal material is a full-spectrum light-absorbing two-dimensional molybdenite composite material.

[0042] Comparative Example 1 This comparative example provides a MoS 2 The method for preparing a photothermal material comprises the following steps: S1. A molybdenite sheet (the length and width of the molybdenite sheet are both 1 cm, and the thickness is 1 mm) is used as a cathode. The cathode and anode (the anode is graphite) are placed in an electrolyte and connected to a power supply for electrolysis to obtain an expanded molybdenite sheet. The expanded molybdenite sheet is ground to obtain a stripping product. The process parameters of the electrochemical stripping control are: the electrolyte is 0.5 mol / L NaOH solution, the current density is 0.02 A / cm 2 , the electrolytic stripping time is 10h; The stripped product was added to DMF and ultrasonicated for 6 h, then centrifuged at 6000 rpm for 20 min and freeze-dried to obtain MoS 2 Nanosheets; S2, 20 mg MoS 2 The nanosheets, 1 ml of PTFE and 5 ml of ethanol were mixed and ultrasonicated for 30 min to make them dispersed evenly to obtain a dispersion; S3, the dispersion is evenly coated on the non-woven fabric, and MoS is obtained after natural drying.2 Photothermal materials.

[0043] Performance Testing Figure 1 This is a physical picture of the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1; Figure 2 A diagram of a photothermal evaporation device assembled from the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1.

[0044] Figure 2 Water is added into a container and blue foam (polystyrene foam, which serves to insulate heat) is placed above the water. At the same time, a limiting hole is opened on the foam, and the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1 is embedded in the limiting hole. The non-protective cloth at the bottom of the full-spectrum light-absorbing two-dimensional molybdenite composite material is in contact with water for performance testing.

[0045] Figure 3 This is an optical microscope image of the nonwoven fabric used in Example 1. The nonwoven fabric is a material formed by combining a large number of randomly arranged fibers through physical or chemical methods. The fibers are interlaced and overlapped in three-dimensional space to form a highly porous network structure. This unique structure gives the nonwoven fabric abundant pores and channels, making it have excellent air permeability, filtration and liquid transmission properties.

[0046] Figure 4 This is an optical microscope image of the full-spectrum light-absorbing two-dimensional molybdenite composite material prepared in Example 1, loaded with MoS 2 -Pd, the surface morphology of the nonwoven fabric changed significantly, and its roughness increased significantly, which indicates that MoS 2 -Pd was successfully and evenly attached to the nonwoven surface. 2 -Pd loading and the use of PTFE binder, the gaps between the nonwoven fibers were partially filled, resulting in a decrease in the porosity of the overall structure and a more compact morphology.

[0047] Figure 5 The MoS prepared in step S1 of Example 1 2 TEM image of nanosheets. Figure 5 It can be seen that MoS 2 The typical layered structure of MoS has a lattice spacing of 0.2795 nm, which is consistent with 2 The layered structure is clearly visible, indicating that MoS 2 Has good crystallinity.

[0048] Figure 6 The MoS prepared in step S2 of Example 1 2 -TEM images of Pd composite materials, from Figure 6 It can be seen that the Pd clusters are uniformly distributed on MoS 2 . By counting the sizes of 200 Pd clusters, their average size is 8.18 ± 2.08 nm.

[0049] Figure 7 It is the MoS prepared in step S2 of Example 1 2 -Pd composite material and the XRD pattern of the MoS 2 nanosheets in step S1.

[0050] From Figure 7 it can be seen that the XRD pattern of the MoS 2 nanosheets shows that the positions of its diffraction peaks are exactly the same as the data in the standard card (JCPDS). The diffraction peaks observed at 14.39°, 33.80°, 39.65°, 44.14°, 49.87°, 58.56° and 60.64° correspond to the (002), (101), (103), (006), (105), (008) and (112) crystal planes of MoS 2 respectively. It is worth noting that there are almost no other miscellaneous peaks in the diffraction pattern of the exfoliated MoS 2 , indicating that the sample has extremely high purity and is not affected by other impurities or phases. The diffraction peaks in the XRD pattern of MoS 2 -Pd are slightly different from the diffraction peaks of MoS 2 , especially on the diffraction peak of the (101) crystal plane of MoS 2 . All the diffraction peaks of MoS 2 in the MoS 2 -Pd sample show a high-angle shift of about 0.4° compared with the diffraction peaks of the exfoliated MoS 2 . In addition, the strongest diffraction peak appears at 39.86°, and this peak does not exactly correspond to the (101) crystal plane of MoS 2 , but is caused by the overlap of the Pd(111) and MoS 2 (101) diffraction peaks. The diffraction peak of the Pd(111) crystal plane is located at 40.12°, while the diffraction peak of the MoS2 (101) crystal plane is located at 39.65°, and the angles of the two are very close. Therefore, when the diffraction peak of the Pd cluster overlaps with the diffraction peak of MoS 2 , a composite peak is formed, and the highest peak point of the peak appears at 39.86°, showing the characteristics of the superposition of the two diffraction signals.

[0051] Figure 8 It is the XPS pattern of the MoS 2 -Pd composite material prepared in step S2 of Example 1.

[0052] From Figure 8 It can be seen that the characteristics of the Pd 3d electron orbit are manifested as two obvious peaks: Pd 3d5 / 2 and Pd3d3 / 2. These two peaks are located at binding energy positions of 335.68 eV and 341.08 eV, respectively. The energy difference between the two peaks is 5.32 eV, which is consistent with the spin-orbit coupling characteristics of palladium metal. The position and energy splitting of the Pd 3d peak are consistent with the standard values ​​of known metallic palladium, further indicating that the palladium in the sample exists in a metallic state. However, the binding energy of Pd 3d5 / 2 is 335.68 eV, which is slightly higher than the typical value of metallic Pd0, 335.0 eV.

[0053] Figure 9-11 The full-spectrum light-absorbing two-dimensional molybdenite composite material finally prepared in Example 1 and the MoS prepared in Comparative Example 1 2 Photothermal materials, mass loss curves, water evaporation rates and photothermal conversion efficiency of Bohai Sea water under 1 sun intensity (about 1000 W / m²) for different materials; Figures 9-11 In MoS 2 -Pd is the full-spectrum light-absorbing two-dimensional molybdenite composite material finally prepared in Example 1, MoS 2 The MoS prepared in Comparative Example 1 2 Photothermal material, Pure water refers to the initial Bohai Sea water used. Fig. 9 The full-spectrum light-absorbing two-dimensional molybdenite composite material in Example 1 and the MoS in Comparative Example 1 2 The mass loss of Bohai Sea water changes with time during the evaporation experiment of photothermal materials; Fig. 9 Pure water means that the mass loss of Bohai Sea water evaporated without using photothermal materials under natural conditions changes with time; Fig.10 The full-spectrum light-absorbing two-dimensional molybdenite composite material in Example 1 and the MoS in Comparative Example 1 2 The photothermal material was subjected to evaporation experiment for 1 hour, and the water evaporation rate diagram; Fig.10 Pure water means that the water evaporation rate of Bohai Sea water is 1h under natural conditions without using photothermal materials; Fig.11 The full-spectrum light-absorbing two-dimensional molybdenite composite material in Example 1 and the MoS in Comparative Example 1 2 The photothermal material was subjected to evaporation experiment for 1 hour, and the photothermal conversion efficiency diagram; Fig.10 Pure water means that no photothermal materials are used in the Bohai Sea water, and the photothermal conversion efficiency of the Bohai Sea water evaporated for 1 hour under natural conditions.

[0054] The test method is as follows: Figure 2As shown in the figure, the photothermal evaporation device was assembled to conduct a water evaporation experiment; the water used was seawater from the Bohai Sea, which contained NaCl, MgCl 2 , KCl, CaCl 2 , the concentration of NaCl in seawater is 10900 mg / L, MgCl 2 The concentration is 1310 mg / L, the concentration of KCl is 390 mg / L, and the concentration of CaCl 2 The concentration is 410 mg / L.

[0055] The calculation formula for water mass loss (Mass Change) is:

[0056] Where m is the mass loss of water, m 1 is the mass of seawater before evaporation, m 2 is the mass of seawater after evaporation, S is the evaporation area (1cm 2 ).

[0057] The calculation formula of water evaporation rate is:

[0058] Where V is the water evaporation rate, m 1 is the mass of seawater before evaporation, m 2 is the mass of seawater after evaporation, S is the evaporation area (1cm 2 ), T is the evaporation time, V 自然蒸发 The speed is 0.184 kg·m -2 ·h -1 (In Example 1 and Comparative Example 1, the natural evaporation rate of water (V 自然蒸发 ).

[0059] The calculation formula of photothermal conversion efficiency (Evaporation efficiency) is:

[0060] In the formula, is the photothermal conversion efficiency, is the evaporation rate of water, C p is the specific heat capacity of water (4.186 J / (g·°C)), ΔT is the difference between the steam temperature and the ambient temperature, and I is the nominal solar intensity (1 kW·m -2 ), C opt is the light intensity concentration (taken as 1), ∆ vap H m is the potential enthalpy of evaporation of water at the corresponding temperature. The ∆vap H m (i.e. 2257 kJ·kg -1 ).

[0061] from Figures 9-11 It can be seen that in terms of water evaporation rate, MoS 2 The water evaporation rate of -Pd is 1.206 kg·m -2 ·h -1 , significantly higher than MoS 2 1.053 kg·m -2 ·h -1 , increased by 14.5%; in terms of light-to-heat conversion efficiency, MoS 2 -Pd evaporation efficiency reached 85.03%, significantly higher than that of MoS 2 The improvement is mainly attributed to the localized surface plasmon resonance effect. The introduction of Pd clusters enhances the photothermal conversion ability of the material and accelerates the conversion of light energy into thermal energy.

[0062] Fig.12 The MoS prepared in step S2 of Example 1 2 -Pd composite material and MoS in step S1 2 UV-visible diffuse reflectance image of the nanosheets.

[0063] from Fig.12 As can be seen from the figure, with the addition of Pd clusters, MoS 2 -The light absorption capacity of Pd composite materials is significantly improved, especially in the near-infrared region, where the absorbance is increased by 30%-60%, thus achieving a full-spectrum absorption effect.

[0064] Fig.13 In accordance with Figure 2 As shown in the assembled photothermal evaporation device diagram, the full-spectrum light-absorbing two-dimensional molybdenite composite material finally prepared in Example 1 was used to carry out an evaporation experiment on Bohai Sea water (under a 1 sun intensity (about 1000 W / m 2 ) under the condition of 1h of experimental time), after 1h of evaporation, the condensed water was collected and the Na + Mg 2+ , K + , Ca 2+ The concentration of Fig.13 shown. Fig.13 Before desalination means the Na content in Bohai Sea water before evaporation experiment. + Mg 2+ , K + , Ca 2+The concentrations were 10900 mg / L, 1310 mg / L, 390 mg / L, and 410 mg / L, respectively. After desalination means that after the evaporation experiment, the Na + Mg 2+ , K + , Ca 2+ of concentrations (the concentrations were 0.314 mg / L, 0.009 mg / L, 0.096 mg / L, and 0.024 mg / L respectively).

[0065] from Fig.13 It can be seen that after evaporation, Na + Mg 2+ , K + and Ca 2+ The concentrations of major ions such as iodine and fecal tract are significantly reduced, by at least three orders of magnitude, and meet the WHO drinking water standards.

[0066] Further, according to the same method as above, the full-spectrum light-absorbing two-dimensional molybdenite composite material finally prepared in Example 1 and the MoS prepared in Comparative Example 1 were tested. 2 Photothermal materials, different materials were used to evaporate Bohai Sea water for 1 hour under 1 sun intensity (about 1000 W / m²), and the photothermal materials after evaporation were subjected to the same evaporation experiment again, and the cycle was repeated 10 times. The water evaporation rate measured each time was as follows Fig.14 shown.

[0067] from Fig.14 It can be seen that the full-spectrum absorption two-dimensional molybdenite composite material still maintains a very stable evaporation rate after 10 cycles, with an evaporation rate of 1.192 kg·m -2 ·h -1 .

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a full-spectrum light-absorbing two-dimensional molybdenite composite material, characterized in that: The following steps are involved: MoS2 nanosheets were combined with Pd clusters to obtain MoS2-Pd composite materials; After mixing MoS2 nanosheets with polytetrafluoroethylene, the mixture is coated on a non-woven fabric and dried to obtain a MoS2 photothermal material; The MoS2-Pd composite material is mixed with polytetrafluoroethylene, coated on a non-woven fabric, and dried to obtain a full-spectrum light-absorbing two-dimensional molybdenite composite material.

2. The method for preparing the full-spectrum light-absorbing two-dimensional molybdenite composite material according to claim 1, characterized in that: The preparation method of the MoS2 nanosheets comprises the following steps: Using the molybdenite sheet as a cathode, placing the cathode and the anode in an electrolyte and connecting them to a power source for electrolysis to obtain an expanded molybdenite sheet; Grinding the expanded molybdenite flakes to obtain an exfoliation product; The exfoliated product was sonicated and centrifuged to obtain MoS2 nanosheets; The process parameters of electrochemical stripping control are: the electrolyte is 0.5~0.8 mol / L NaOH solution, the current density is 0.02~0.03A / cm 2 The electrolytic stripping time is 10~12h.

3. The method for preparing the full-spectrum light-absorbing two-dimensional molybdenite composite material according to claim 2, characterized in that: The MoS2 nanosheets and Pd clusters are compounded to obtain a MoS2-Pd composite material, which specifically includes: The MoS2 nanosheets are dispersed in DMF, and then a precursor solution containing PdCl2 is added, hydrothermally reacted, filtered, washed, and dried to obtain a MoS2-Pd composite material.

4. The method for preparing the full-spectrum light-absorbing two-dimensional molybdenite composite material according to claim 3, characterized in that: The hydrothermal reaction temperature is 140~150℃ and the time is 6~10h.

5. The method for preparing the full-spectrum light-absorbing two-dimensional molybdenite composite material according to claim 3, characterized in that: The precursor solution containing PdCl2 includes: palladium chloride, hydrochloric acid, and polyvinyl pyrrolidone; The molar ratio of palladium chloride, hydrochloric acid and polyvinyl pyrrolidone is (1-2):(1-3):(1-2).

6. The method for preparing the full-spectrum light-absorbing two-dimensional molybdenite composite material according to claim 3, characterized in that: The concentration of PdCl2 in the precursor solution containing PdCl2 is 1-2 mg / mL.

7. The method for preparing the full-spectrum light-absorbing two-dimensional molybdenite composite material according to claim 3, characterized in that: The mass volume ratio of the MoS2 nanosheets, DMF, and the precursor solution containing PdCl2 is (150-160) mg: (150-160) mL: (1-2) mL; And / or, MoS2 nanosheets, polytetrafluoroethylene and ethanol are mixed, coated on a non-woven fabric and dried to obtain a MoS2 photothermal material; The MoS2-Pd composite material, polytetrafluoroethylene and ethanol are mixed, coated on a non-woven fabric and dried to obtain a full-spectrum light-absorbing two-dimensional molybdenite composite material; Among them, the mass volume ratio of MoS2-Pd composite material, polytetrafluoroethylene, and ethanol is (20~30) mg: (1~2) mL: (5~10) mL; And / or, in the step of ultrasonicating and centrifuging the exfoliated product to obtain MoS2 nanosheets, the centrifugal speed is 6000~8000rpm and the centrifugal time is 20~30 min.

8. The method for preparing the full-spectrum light-absorbing two-dimensional molybdenite composite material according to claim 3, characterized in that: The non-woven fabric is blended from cotton and polypropylene fibers.

9. A full-spectrum light-absorbing two-dimensional molybdenite composite material, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 9.

10. A full-spectrum light-absorbing two-dimensional molybdenite composite material as claimed in claim 9 as a solar-driven interfacial evaporation material for seawater desalination or high-salinity wastewater treatment.

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