A method for preparing ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency

Abstract

This invention belongs to the field of nanomaterial synthesis technology and relates to a method for preparing ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency. Using CuCl2·2H2O, ammonium sulfide, oleylamine, or n-octylamine as raw materials, the reaction is carried out at 70-100℃ for 90-180 min. After hydrophilic treatment, monodisperse two-dimensional CuS nanosheets with a thickness of 1.5-2 nm are obtained. These nanosheets exhibit high photothermal conversion efficiency, reaching up to 92±3%.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial synthesis technology and relates to the preparation of an ultrathin, monodisperse two-dimensional CuS nanomaterial with high photothermal conversion efficiency. Background Technology

[0002] Solar energy, due to its green, environmentally friendly, and sustainable characteristics, is highly favored by the environmental and energy sectors. Photothermal conversion is a rapid and efficient form of energy conversion. In photothermal conversion devices, photothermal conversion materials are one of the key components. Among various photothermal materials, two-dimensional photothermal nanomaterials exhibit high photothermal conversion efficiency due to their excellent in-plane electron mobility. Furthermore, their two-dimensional thickness allows for higher mechanical properties, optical transparency, indirect bandgap to direct bandgap transition, and stability of metastable phases. Therefore, two-dimensional photothermal nanomaterials have wide applications in cutting-edge fields, including water evaporation, biomedicine, thermochemical reactions, catalysis, and energy chemistry. Some photothermal materials can convert near-infrared light energy into heat energy, including polymers, noble metal nanocrystals, metal sulfides, and metal oxides. CuS, in particular, exhibits excellent photothermal effects. CuS has also attracted widespread attention due to its low cost, low cytotoxicity, and high photothermal conversion efficiency, and is widely used in cancer treatment, thermosensitive drug delivery, photothermal probes, and water evaporation. Photothermal conversion efficiency is a key characteristic of photothermal materials, reflecting the rate at which the material converts light energy into heat energy. Therefore, obtaining materials with high photothermal conversion efficiency is a key condition for more effectively converting light energy into heat energy. For two-dimensional nanomaterials, ultrathin structures can give them high spectral surface areas and excellent photothermal effects. Furthermore, due to the ultrathin thickness of two-dimensional nanomaterials, large-area photothermal devices can be fabricated with a small amount of two-dimensional photothermal material, thus significantly reducing material costs. For CuS, optimizing its size, shape, and composition can further improve its optical properties, thereby promoting photothermal effects.

[0003] Currently, for non-stoichiometric Cu 2-x There are many reports on CuS nanomaterials, but there are few reports on the preparation methods of ultrathin CuS nanosheets with high photothermal conversion efficiency. Therefore, this invention is proposed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency. These nanosheets exhibit high photothermal conversion efficiency, reaching up to 92±3%.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for preparing ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency includes the following steps:

[0007] Using CuCl2·2H2O, ammonium sulfide, oleylamine or n-octylamine as raw materials, the samples were reacted at 70-100℃ for 90-180 min. After hydrophilic treatment, ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency were obtained.

[0008] The above preparation method includes CuS nanosheet synthesis and hydrophilic treatment.

[0009] The steps involved in the synthesis of the CuS nanosheets are as follows:

[0010] 1) Add CuCl2·2H2O to a mixture of oleylamine or n-octylamine and toluene, and stir and heat in a rare gas atmosphere;

[0011] 2) Inject ammonium sulfide and continue stirring and heating to react;

[0012] 3) After the reaction is complete, cool the sample, add isopropanol to the sample, and centrifuge to remove the supernatant;

[0013] 4) Wash the remaining precipitate with toluene and isopropanol (volume ratio of toluene and isopropanol is 1:1) and store it in an organic solvent (such as toluene).

[0014] The hydrophilic treatment steps described above are as follows:

[0015] 5) After centrifuging the sample obtained in step 4), add chloroform (or toluene or dichloromethane) and stir;

[0016] 6) Add the methoxy polyethylene glycol-mercapto solution and continue stirring;

[0017] 7) After stirring, centrifuge to obtain the final product.

[0018] According to the present invention, preferably, in step 1), the ratio of CuCl2·2H2O: oleylamine or n-octylamine: toluene is 2.5-3:10-30:10-30 (mmol:mL:mL); specifically, the added mass of CuCl2·2H2O can be 2.5-3 mmol, oleylamine 10-30 mL, and toluene 10-30 mL. In the present invention, oleylamine or n-octylamine acts as a surfactant and also possesses reducing properties.

[0019] According to the present invention, preferably, the rare gas in step 1) is nitrogen, and when reacting in a nitrogen atmosphere, the nitrogen is introduced for 20-50 minutes.

[0020] According to the present invention, preferably, the heating temperature in steps 1) and 2) is 70-100°C.

[0021] According to the present invention, preferably, in step 2), 30-40 mmol of ammonium sulfide is added and the reaction is stirred and heated for 90-180 min.

[0022] According to the present invention, preferably, the centrifugation speed in step 3) is 4000-7000 r / min and the time is 5-15 min.

[0023] According to the present invention, preferably, the washing agent for dissolving the remaining precipitate after centrifugation in step 4) is toluene and isopropanol. The role of isopropanol is to improve precipitation separation.

[0024] According to the present invention, preferably, the organic solvent for dissolving the remaining precipitate after centrifugation in step 4) is toluene, but it can also be chloroform or dichloromethane.

[0025] According to the present invention, preferably, in step 5), the sample is 5-10 mg, and the chloroform, toluene, or dichloromethane is 5-10 mL, with a mass-to-volume ratio of 1:1.

[0026] According to the present invention, preferably, the centrifugation speed in step 5) is 3000 r / min.

[0027] According to the present invention, preferably, the methoxyvinyl alcohol-mercapto solution in step 6) is a 2-5 mg / mL methoxyvinyl alcohol-mercaptomethanol solution.

[0028] According to the present invention, preferably, the stirring time in step 6) is 24 hours.

[0029] According to the present invention, preferably, in step 7), the centrifugation speed is 8000-12000 r / min for 10-20 min.

[0030] The final product of this invention is a CuS monodisperse nanosheet with a thickness of 1.5-2 nm and a photothermal conversion efficiency of 92±3%.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. The CuS nanosheets of the present invention have atomic-level thickness, as low as 1.5-2 nm. Furthermore, after hydrophilic treatment, they exhibit good monodispersity in organic solvents.

[0033] 2. The CuS nanosheets of this invention have high photothermal conversion efficiency, with a maximum efficiency of 92±3%. Due to their high photothermal conversion rate, they can be applied in fields such as biomedicine and photo-driven intelligent actuators. Attached Figure Description

[0034] Figure 1 These are scanning electron microscope images of the ultrathin CuS nanosheets prepared in Example 1;

[0035] Figure 2 The image shows the XRD pattern of the ultrathin CuS nanosheets prepared in Example 1.

[0036] Figure 3 AFM image of the ultrathin CuS nanosheets prepared in Example 1;

[0037] Figure 4 These are scanning electron microscope images of CuS nanosheets prepared in Example 2;

[0038] Figure 5 These are scanning electron microscope images of the ultrathin CuS nanosheets prepared in Example 3;

[0039] Figure 6 This is a scanning electron microscope image of the hydrophilic CuS nanosheets prepared in Example 4;

[0040] Figure 7 This is a graph showing the photothermal efficiency conversion of the hydrophilic CuS nanosheets prepared in Example 4;

[0041] Figure 8 This is a cyclic stability diagram of the photothermal properties of the hydrophilic CuS nanosheets prepared in Example 4;

[0042] Figure 9 This is a scanning electron microscope image of the hydrophobic CuS nanosheets prepared in Comparative Example 3. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but is not limited thereto. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] Add 3 mmol CuCl2·2H2O, 20 ml oleylamine (OAm), and 20 ml toluene to a 100 ml three-necked flask. Place the flask in a heating mantle and set the temperature to 70 °C. Purge with nitrogen and stir for 30 min. Quickly inject 40 mmol ammonium sulfide into the flask and stir at 70 °C for 90 min. After the reaction is complete, cool in a cold water bath. Add 20 ml isopropanol to the sample and centrifuge at 5000 rpm for 5 min. After centrifugation, remove the supernatant. Wash the remaining precipitate twice with toluene and isopropanol, and finally store in toluene solution for later use.

[0046] The ultrathin CuS nanosheets prepared in this embodiment Figure 2The XRD pattern shows that the prepared nanosheets are indeed CuS. Figure 1 Scanning electron microscope images of the prepared nanosheets, by Figure 1 and 3 It can be seen that the nanosheet has a size of 130 nm and a thickness of 1.5-2 nm.

[0047] Example 2

[0048] The reaction temperature was set to 100℃ and the reaction time was 180 min.

[0049] Add 3 mmol CuCl2·2H2O, 20 ml oleylamine (OAm), and 20 ml toluene to a 100 ml three-necked flask. Place the flask in a heating mantle and set the temperature to 100 °C. Purge with nitrogen and stir for 30 min. Quickly inject 40 mmol ammonium sulfide into the flask and stir at 100 °C for 180 min. After the reaction is complete, cool in a cold water bath. Add 20 ml isopropanol to the sample and centrifuge at 5000 rpm for 5 min. After centrifugation, remove the supernatant. Wash the remaining precipitate twice with toluene and isopropanol, and finally store in toluene solution for later use.

[0050] The scanning electron microscope image of the ultrathin CuS nanosheets prepared in this embodiment is shown as follows. Figure 4 As shown. Its dimensions are 90nm and its thickness is 1.5-2nm.

[0051] Example 3

[0052] Replace oleylamine, which is used as a surfactant in the solvent, with n-octylamine.

[0053] Add 3 mmol CuCl2·2H2O, 20 ml n-octylamine, and 20 ml toluene to a 100 ml three-necked flask. Place the flask in a heating mantle and set the temperature to 70 °C. Purge with nitrogen and stir for 30 min. Quickly inject 40 mmol ammonium sulfide into the flask and stir at 70 °C for 90 min. After the reaction is complete, cool in a cold water bath. Add 20 ml isopropanol to the sample and centrifuge at 5000 rpm for 5 min. After centrifugation, remove the supernatant. Wash the remaining precipitate twice with toluene and isopropanol, and finally store in toluene solution for later use.

[0054] The scanning electron microscope image of the ultrathin CuS nanosheets prepared in this embodiment is shown as follows. Figure 5 As shown. Its size is 90nm, and its thickness is maintained at 1.5-2nm.

[0055] Example 4

[0056] CuS nanosheets with methoxy polyethylene glycol-thiol as a surface treatment agent.

[0057] Take 5 mg of CuS nanosheets prepared in Example 1 and add 5 ml of chloroform. Place in a glass bottle and stir. Dissolve 3 mg of methoxy polyethylene glycol-mercapto-methyl in 1 ml of methanol and add to the above glass bottle, stirring for 24 h. Centrifuge at 10000 r / min for 20 min. The dispersibility is better after hydrophilic treatment, such as... Figure 6 As shown.

[0058] According to the photothermal conversion formula:

[0059]

[0060] The calculated photothermal conversion efficiency η reaches 92±3%, and the temperature rise and fall curves are as follows: Figure 7 The cycling stability of nanosheets is as follows Figure 8 As shown.

[0061] Comparative Example 1

[0062] As in Example 1, the reactants were placed at 35°C for reaction, and no plate-like structure was formed in the end.

[0063] Comparative Example 2

[0064] Add 60.8 mg of cuprous thiocyanate and 10 ml of oleylamine (OAM) to a 50 ml three-necked flask. Place the flask in a heating mantle and set the temperature to 80 °C. Stir under vacuum for 30 min. Then, purge with nitrogen and heat to 240 °C, stirring for another 30 min. After the reaction is complete, cool in a cold water bath. Add 10 ml of isopropanol to the sample and centrifuge at 5000 rpm for 10 min. After centrifugation, remove the supernatant. Wash the remaining precipitate twice with toluene and isopropanol, and finally store in toluene solution for later use. The photothermal conversion efficiency is low.

[0065] Comparative Example 3

[0066] Take 5 mg of the CuS nanosheets prepared in Example 1 and add 5 ml of chloroform. Place in a glass bottle and stir. Dissolve 3 mg of n-dodecyl mercaptan in 1 ml of methanol and add to the above glass bottle, stirring for 24 h. Centrifuge at 10000 rpm for 10 min. Due to the lack of hydrophilic ligands, the nanosheets will not disperse uniformly and will stack. Figure 9 As shown.

[0067] The upper and lower limits of the process parameters (such as temperature, time, etc.) and the range values ​​of the present invention can all achieve the method, and examples are not listed here.

[0068] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency, the method comprising the following steps: Using CuCl2·2H2O, ammonium sulfide, oleylamine or n-octylamine as raw materials, the samples were reacted at 70-100℃ for 90-180 min. After hydrophilic treatment, ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency were obtained. The synthesis includes the following specific steps: 1) Add CuCl2·2H2O to a mixture of oleylamine or n-octylamine and toluene, and stir and heat in a rare gas atmosphere; 2) Inject ammonium sulfide and continue stirring and heating to react; 3) After the reaction is complete, cool the sample, add isopropanol to the sample, and centrifuge to remove the supernatant; 4) Wash the remaining precipitate with toluene and isopropanol, and store it in an organic solvent; The hydrophilic treatment includes the following specific steps: After centrifuging the sample obtained in step 4), add it to chloroform, toluene or dichloromethane and stir; then add a hydrophilic treatment agent solution and continue stirring. After stirring, centrifuge to obtain ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency. The hydrophilic treatment agent solution is a methoxy polyethylene glycol-mercapto solution.

2. The preparation method according to claim 1, characterized in that, In step 1), the molar mass of CuCl2·2H2O added is 2.5-3 mmol, the amount of oleylamine or n-octylamine is 10-30 mL, and the amount of toluene is 10-30 mL.

3. The preparation method according to claim 1, characterized in that, In step 1), the rare gas introduced is nitrogen, and the nitrogen is introduced for 20-50 minutes during the reaction in a nitrogen atmosphere.

4. The preparation method according to claim 1, characterized in that, In step 2), add 30-40 mmol of ammonium sulfide and heat for 90-180 min.

5. The preparation method according to claim 1, characterized in that, In step 3), the centrifugation speed is 4000-7000 r / min and the time is 5-15 min.

6. The preparation method according to claim 1, characterized in that, In the hydrophilic treatment, the mass-to-volume ratio of the sample to chloroform, toluene, or dichloromethane is 1:

1.

7. The preparation method according to claim 1, characterized in that, The methoxy polyethylene glycol-mercapto-methanol solution is a methoxy polyethylene glycol-mercapto-methanol solution with a concentration of 2-5 mg / mL.

8. The preparation method according to claim 1, characterized in that, After stirring, centrifugation was performed to obtain ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency. The centrifugation speed was 8000-12000 r / min and the centrifugation time was 10-20 min.

9. The preparation method according to claim 1, characterized in that, The thickness of the ultrathin two-dimensional CuS nanosheets with high photothermal conversion efficiency is 1.5-2 nm; the photothermal conversion efficiency is 92±3%.

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