An efficient photothermal conversion material, photothermal conversion film, preparation method and application

Abstract

The present invention relates to an efficient photothermal conversion material, a photothermal conversion film, a preparation method and an application, and relates to the field of photothermal conversion materials. The photothermal conversion material is MXene / Au@Cu<subgt;2-x< / subgt;S, where 0 < x < 2, and the MXene / Au@Cu<subgt;2-x< / subgt;S is obtained by chemically combining MXene nanosheets and Au@Cu<subgt;2-x< / subgt>S core-shell heterostructured materials. The Au@Cu<subgt;2-x< / subgt>S core-shell heterostructured material constructed in the present invention combines the strong coupling between a nano-metal with surface plasmon resonance effect and a semiconductor, improving the photothermal conversion efficiency. The Au@Cu<subgt;2-x< / subgt>S core-shell heterostructured material is combined with ultrathin MXene nanosheets through chemical bonds to obtain the photothermal conversion material MXene / Au@Cu<subgt;2-x< / subgt>S, which has good light absorption from visible light to near-infrared and has an excellent synergistic photothermal conversion effect. When the photothermal conversion material MXene / Au@Cu<subgt;2-x< / subgt>S is used for seawater desalination or sewage purification, it has a high water evaporation rate, stability, and excellent seawater desalination and sewage treatment effects.

Description

Technical Field

[0001] The present invention relates to the field of photothermal conversion materials, and particularly to an efficient photothermal conversion material, a photothermal conversion film, a preparation method and an application thereof. Background Art

[0002] Solar-driven interfacial water evaporation is an emerging technology based on photothermal conversion. This technology can utilize solar energy to produce clean water from seawater and industrial wastewater, thereby solving the problem of water resource shortage. Currently, this technology has been applied to the fields of water purification and environmental treatment. During the water evaporation process, the performance of the interfacial photothermal water evaporation material has a crucial impact on achieving a high water evaporation rate.

[0003] An ideal interfacial photothermal water evaporation material should have good light absorption ability in the full spectrum and a high photothermal conversion efficiency, so as to be able to effectively convert the absorbed solar energy into heat energy. At the same time, the interfacial photothermal water evaporation material should have good heat insulation ability and water absorption ability. Currently, MXene has been theoretically proven to be an excellent photothermal material with a photothermal conversion efficiency of nearly 100%. Meanwhile, photothermal conversion materials based on MXene have been successively reported. However, single MXene still has some disadvantages, such as insufficient broadband light absorption ability in the middle, which limits its photothermal conversion efficiency, etc. It has been found that combining MXene with other materials having excellent light absorption and photothermal conversion rates can improve the overall photothermal performance. Up to now, there are still challenges in developing interfacial photothermal conversion materials with high water evaporation rate and stability. In view of this, the present invention provides an efficient photothermal conversion material, a photothermal conversion film, a preparation method and an application thereof. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an efficient photothermal conversion material, a photothermal conversion film, a preparation method and an application thereof. The aim is to develop a photothermal conversion material MXene / Au@Cu 2-x S with a high water evaporation rate and stability, and use it for the treatment of seawater desalination or sewage purification.

[0005] To solve the above technical problems, the first object of the present invention is to provide an efficient photothermal conversion material, and the photothermal conversion material is MXene / Au@Cu 2-x S, where 0 < x < 2, and the MXene / Au@Cu 2-x S is obtained by chemically compounding MXene nanosheets and Au@Cu 2-x S core-shell heterostructure materials, and the molar ratio of the MXene nanosheets to the Au@Cu 2-x S core-shell heterostructure materials is 1:(0.1 - 1).

[0006] The beneficial effects of the present invention are as follows: The Au@Cu 2-x S core-shell heterogeneous material constructed by the present invention has a strong coupling between the nano-metal with surface plasmon resonance effect and the semiconductor, which improves the photothermal conversion efficiency. The Au@Cu 2-x S core-shell heterogeneous material is combined with the ultrathin MXene nanosheets through chemical bonds to obtain the photothermal conversion material MXene / Au@Cu 2-x S, which has good light absorption from visible light to near-infrared and has an excellent synergistic photothermal conversion effect; the photothermal conversion material MXene / Au@Cu 2-x S is used for seawater desalination or sewage purification, and has a high water evaporation rate, stability, and excellent seawater desalination and sewage treatment effects.

[0007] Based on the above technical solutions, the present invention can also be improved as follows.

[0008] Furthermore, the molar ratio of the MXene nanosheets to the Au@Cu 2-x S core-shell heterogeneous material is 1:(0.3 - 0.8).

[0009] The beneficial effect of adopting the above further solution is that: the MXene nanosheets and the Au@Cu 2-x S core-shell heterogeneous material are chemically compounded according to the molar ratio of 1:(0.3 - 0.8), and the obtained MXene / Au@Cu 2-x S has the best high water evaporation rate and stability.

[0010] Further, the Au@Cu 2-x S core-shell heterogeneous material includes any one or a combination of at least two of Au NSR@Cu 2-x S core-shell heterogeneous material, Au NS@Cu 2-x S core-shell heterogeneous material, and Au NR@Cu 2-x S core-shell heterogeneous material. Among them, AuNR refers to Au nanorods, Au NS is Au nanospheres, and Au NSR is a mixture of Au nanorods and nanospheres, that is, Au NSR@Cu 2-x S is AuNR@Cu 2-x S / AuNS@Cu 2-x S.

[0011] The second object of the present invention is to provide a preparation method of an efficient photothermal conversion material, including the following steps: First, the MXene nanosheets and Au@Cu 2-xMix the S core-shell heterostructured material, and then perform ultrasonic treatment for 0.5 - 2 h. Then, centrifuge the product obtained by ultrasonic treatment at 4000 - 7000 rpm / min for 2 - 10 min, remove the supernatant, and obtain the photothermal conversion material MXene / Au@Cu 2-x S.

[0012] The beneficial effects of adopting the above scheme are as follows: Mix the MXene nanosheets and the Au@Cu 2-x S core-shell heterostructured material, and then perform ultrasonic treatment, which can enable the oxygen-containing groups in MXene and S in Au@Cu 2-x S to form S-O bonds. The formation of chemical bonds can also accelerate charge transfer and improve the photothermal conversion efficiency.

[0013] Furthermore, the preparation method of the Au@Cu 2-x S core-shell heterostructured material includes the following specific steps:

[0014] Step 1, prepare a nano-gold colloid solution: Mix a mixed solution of chloroauric acid, cetyltrimethylammonium bromide, and sodium borohydride with a molar ratio of (0.03 - 0.1):(10 - 50):(3 - 6) at 30 - 40 °C for 0.5 - 2 h to obtain a gold seed solution; Then, take chloroauric acid and cetyltrimethylammonium bromide according to a molar ratio of (3 - 10):1000, mix them, and then add silver nitrate, hydrochloric acid, ascorbic acid, and the gold seed solution in sequence. The dosage ratio of silver nitrate, hydrochloric acid, ascorbic acid, and the gold seed solution is (0.2 - 0.8):(5 - 12):(5 - 12):(0.02 - 0.18). Mix them again and perform an overnight reaction at room temperature. Centrifuge the reaction product obtained by the reaction at 5000 - 10000 rpm / min for 5 - 15 min, remove the supernatant, and obtain gold nanorods and / or nanospheres. Disperse the gold nanorods or nanospheres in deionized water. The dosage ratio of the gold nanorods or nanospheres to deionized water is (5×10 -4 ~1×10 -3 ):1 to obtain a nano-gold colloid solution;

[0015] Step 2, Au@Cu 2-xPreparation of S core-shell heterostructured material: First, take ascorbic acid solution, cetyltrimethylammonium bromide, and hexamethylenetetramine according to the dosage ratio of 0.1:1:0.1, mix them and add them to the above-mentioned nano-gold colloid solution to obtain a mixture solution; then add copper nitrate and thioacetamide solution to the mixture solution, and the dosage ratio of the nano-gold colloid solution, copper nitrate, and thioacetamide is 1:(0.5 - 2):(1 - 4). Then transfer it to an incubator at 95 ± 2 °C and place it for 6 - 10 h for reaction. Centrifuge the obtained reaction product at 5000 - 8000 rpm / min for 3 - 8 min, remove the supernatant to obtain Au@Cu 2-x S core-shell heterostructured material.

[0016] The beneficial effect of adopting the above further scheme is that the present invention can make Cu 2-x S grow on the gold rod by using the convenient hydrothermal method to form a heterojunction with a core-shell structure, accelerate charge transfer, and improve the photothermal conversion efficiency.

[0017] Further, the MXene nanosheet is Ti3C2T x .

[0018] Among them, MXene with a graphene-like 2D structure is widely used in catalysts, ion sieving, photothermal conversion, field effect transistors, topological insulators, and hydrogen evolution reactions. The Ti3C2T x adopted in this application has a graphene-like 2D structure, and T in Ti3C2T x represents the surface terminal, including OH, O, or F.

[0019] Further, the preparation method of the Ti3C2T x includes the following specific steps: Slowly add lithium fluoride to hydrochloric acid, and the dosage ratio of lithium fluoride and hydrochloric acid is 1:1 to form an HCI / LiF etching solution; under stirring and ice-water bath, slowly add Ti3AlC2 to the HCI / LiF etching solution, and the mass ratio of Ti3AlC2 to lithium fluoride is (1 - 5):(1 - 5). First, stir at room temperature for 1 - 2 min, then in an oil bath at a temperature of 25 - 35 °C, react under stirring conditions for 20 - 28 h to completely remove the aluminum layer. Then, centrifuge, wash, vacuum deoxygenate, ultrasonicate under ice-water bath conditions, and vacuum dry the obtained reactants in sequence to obtain Ti3C2T x .

[0020] Specifically, centrifuge the obtained reactants at 3500 rpm / min for 5 - 10 min in sequence, centrifuge and wash at 3500 - 5000 rpm / min, vacuum deoxygenate, ultrasonicate for 0.5 - 2 h under ice-water bath conditions, and vacuum dry to obtain Ti3C2T xAmong them, the vacuum condition refers to a vacuum degree of 0.1 Pa and a temperature of 60 °C.

[0021] The third object of the present invention is to provide a photothermal conversion film, and the photothermal conversion film includes the above-mentioned efficient photothermal conversion material MXene / Au@Cu 2-x S, 0 < x < 2.

[0022] The fourth object of the present invention is to provide a preparation method of a photothermal conversion film, including the following steps: adsorbing the above-mentioned efficient photothermal conversion material MXene / Au@Cu 2-x S on a hydrophilic cotton sheet, and the mass ratio of the above-mentioned efficient photothermal conversion material MXene / Au@Cu 2-x S to the hydrophilic cotton sheet is 1:(0.1 - 1) to obtain a photothermal conversion film.

[0023] The beneficial effect of using the photothermal conversion film in the above solution is that by adsorbing the synthesized MXene / Au@Cu 2-x S material onto a hydrophilic cotton sheet, it serves as the core light-absorbing and photothermal conversion film.

[0024] The fifth object of the present invention is to provide an application of a photothermal conversion film, and the above-mentioned photothermal conversion film is used for seawater desalination or sewage purification.

[0025] Furthermore, the photothermal conversion film is placed on the upper surface of a heat-insulating material wrapped with absorbent paper for seawater desalination or sewage purification.

[0026] The present invention forms an interfacial photothermal conversion film by placing the photothermal conversion film on the upper surface of a heat-insulating material wrapped with absorbent paper for seawater desalination or sewage purification. The beneficial effect of adopting the above solution is:

[0027] (1) It has a high water evaporation rate and stability: Under the light source condition of one sun power, the water evaporation rate is about 1.98 kg·m -2 ·h -1 , and it still maintains 98% of the initial rate after 10 cycles (10 h), indicating good photothermal stability and durability. That is, the above-mentioned measurement results of solar-driven water evaporation show that the MXene / Au@Cu 2-x S interfacial photothermal conversion film has great potential in water purification and seawater desalination. Experimental data shows that the light absorption rate of the MXene / Au@Cu 2-x S interfacial photothermal conversion film under one sun condition irradiation is about 96%, and the best evaporation rate is 2.023 kg·m -2 ·h -1 .

[0028] (2) It has excellent seawater desalination effect: When using this interfacial photothermal conversion film to treat seawater under sunlight conditions, the concentrations of four main ions in the solution, namely Na + , Mg 2+ , Ca 2+ and K + , are monitored by an ion chromatograph. The results show that in the presence of the interfacial photothermal conversion film (MXene / Au@Cu 2-x S film), the concentrations of the four desalinated ions are reduced by 3 to 4 orders of magnitude. And these concentrations are far lower than the safe salinity levels defined by the standards of the World Health Organization (WHO) and the US Environmental Protection Agency (EPA), reaching the drinking standard.

[0029] (3) It has excellent sewage treatment effect: In the application of treating polluted water, this interfacial photothermal conversion film is used to treat sewage under sunlight conditions. The results show that the extinction coefficients of rhodamine and methylene blue in the solution are detected by a UV-3600 ultraviolet-visible near-infrared spectrophotometer. Among them, the absorption peaks at 554 nm and 664 nm correspond to rhodamine and methylene blue respectively, and these two peaks are almost completely eliminated after evaporation, indicating that the MXene / Au@Cu 2-x S interfacial photothermal conversion film has good water purification ability. Description of the Drawings

[0030] Figure 1 This is the TEM image of the MXene / Au NSR@Cu 2-x S material of the present invention;

[0031] Figure 2 This is the SEM image of the hydrophilic cotton sheet of the present invention;

[0032] Figure 3 This is the SEM image of the hydrophilic cotton sheet after adsorbing the MXene / Au NSR@Cu 2-x S material of the present invention;

[0033] Figure 4 This is the comparison chart of the change curve of the water evaporation rate over time of the MXene / Au NSR@Cu 2-x S material of the present invention and a relatively single material under one-sun condition;

[0034] Figure 5 This is the comparison chart of the cycle number and evaporation rate of the MXene / Au NSR@Cu 2-x S material of the present invention;

[0035] Figure 6 This is the comparison chart of the water evaporation rates of Mxene, M / Cus, M / Au, M / As@C, M / AR@C and M / ASR@C of the present invention under one-sun condition;

[0036] Figure 7 For the present invention, the MXene / Au NSR@Cu 2-x S interface photothermal conversion film is used for the comparison chart of the changes in the content of key ions before and after seawater desalination of artificial seawater;

[0037] Figure 8 For the present invention, the MXene / Au NSR@Cu 2-x S interface photothermal conversion film is used for the comparison chart of the changes in the ultraviolet absorption peaks of rhodamine and methylene blue dyes before and after freshwater purification of rhodamine and methylene blue dyes respectively. Detailed implementation manners

[0038] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0039] Examples

[0040] 1. Preparation and characterization of the interface photothermal conversion film

[0041] 1.1 Preparation of the interface photothermal conversion film

[0042] 1.1.1 MXene / Au NSR@Cu 2-x S (MXene / AuNR@Cu 2-x S / AuNS@Cu 2-x S) interface photothermal conversion film

[0043] The preparation of the interface photothermal conversion film involved in this example includes the following steps:

[0044] Step 1: Prepare a colloidal gold solution: Mix 1 ml of 5 mmol / L chloroauric acid, 10 ml of 0.2 M cetyltrimethylammonium bromide solution, and 600 μl of 5 mmol / L sodium borohydride solution, and react for 2 h to synthesize a gold seed solution; then add 5 ml of 10 mmol / L chloroauric acid solution to 25 ml of 0.2 M cetyltrimethylammonium bromide solution and mix and stir for 1 minute; then add 50 μl of 10 mmol / L silver nitrate, 30 μl of 0.1 M hydrochloric acid, 3 ml of 10 mmol / L ascorbic acid, and 35 μl of the gold seed solution, and react overnight at room temperature after mixing. Centrifuge the reaction product obtained at 8000 rpm / min for 10 min to obtain gold nanorods or nanospheres, and then disperse them in deionized water. The molar ratio of the gold nanorods or nanospheres to deionized water is 5×10 -4 :1 to obtain a colloidal gold solution;

[0045] Step 2: Au NSR@Cu 2-xPreparation of S core-shell heterostructured material: First, 1 ml of 0.1 M ascorbic acid solution, 5 ml of 0.2 M cetyltrimethylammonium bromide, and 1 ml of 0.1 M hexamethylenetetramine were respectively taken and mixed, and then added to the nano-gold colloid solution to obtain a mixture solution; then, 600 ul of 10 mmol / L copper nitrate and 1200 ul of 10 mmol / L thioacetamide solution were added to the mixture solution, and then transferred to an incubator at 95 °C and left to react for 8 h. The resulting reaction product was centrifuged at 5000 - 8000 rpm / min for 5 min to obtain Au NSR@Cu 2-x S core-shell heterostructured material, and then redispersed in water for further use;

[0046] Step 3: Preparation of MXene nanosheets: The MXene nanosheets are Ti3C2T x ., 1 g of lithium fluoride was slowly added to a beaker containing 20 ml of 0.1 mol / L hydrochloric acid to form an HCI / LiF etching solution; under magnetic stirring and an ice-water bath, 1 g of Ti3AlC2 was slowly added to the beaker containing the HCI / LiF etching solution, stirred evenly at room temperature, and then placed in an oil bath at 35 °C and magnetically stirred for 24 h to completely remove the aluminum layer. The etched solution was centrifuged at 3500 rpm / min for 7 min, and then the centrifugation speed was increased by 500 rpm / min each time for washing. Then, it was ultrasonically treated for 2 h under vacuum deoxygenation and an ice-water bath, and the resulting suspension was dried in vacuo to finally obtain Ti3C2T x ;

[0047] Step 4: Preparation of MXene / Au NSR@Cu 2-x S material: 10 ug of Ti3C2T x and 5 ug of Au NSR@Cu 2-x S core-shell heterostructured materials were mixed together and ultrasonically treated for 1 h. The resulting product was centrifuged at 5000 rpm / min for 3 min to obtain the photothermal conversion material MXene / Au NSR@Cu 2-x S, and then redispersed in water for further use;

[0048] Step 5: Preparation of the photothermal conversion film: A hydrophilic cotton sheet (with a diameter of 3 cm, whose SEM is as Figure 2 shown) was immersed in the synthesized photothermal conversion material MXene / Au NSR@Cu 2-x S solution for 4 h and repeated 3 times. The mass ratio of the highly efficient photothermal conversion material MXene / Au NSR@Cu 2-x S to the hydrophilic cotton sheet is 15×10 -5 :1, serving as the core light-absorbing and photothermal-converting photothermal conversion film;

[0049] Step 6. Prepare the interfacial photothermal conversion film: Place the MXene / Au NSR@Cu 2-x S film on the upper surface of a polystyrene (PS) foam wrapped with absorbent paper, and a MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film with a high water evaporation rate and stability can be formed.

[0050] 1.1.2 Preparation of MXene / Au NS@Cu 2-x Compared with the preparation of the MXene / AuNSR@Cu 2-x S interfacial photothermal conversion film described in 1.1.1 above, except for the preparation of the gold seed solution, the preparation of the gold nanosphere colloidal solution, and the preparation of the AuNS@Cu 2-x S core-shell heterostructured nanostructure, the rest are the same as those described in 1.1.1 above.

[0051] Among them, for the preparation of the gold seed solution: Obtain uniform gold nanospheres by placing them in a gold nanocolloid solution. Take 5 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 4.5 ml of deionized water solution, 500 μl of a 5 mmol / L chloroauric acid solution, and 600 μl of a 10 mmol / L sodium borohydride solution, place them on a magnetic stirrer for stirring reaction, with a reaction time of 2 h and a rotation speed of 1400 rpm to obtain the gold seed solution.

[0052] For the preparation of the gold nanosphere colloidal solution: Take 40 μl of the gold seed solution obtained in Step 1, add it to a mixed solution of 30 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 6 ml of a 5 mmol / L chloroauric acid solution, and 3.5 ml of a 10 mmol / L ascorbic acid solution, then add 1 ml of a 1 mol / L sodium hydroxide, react at 33 °C for 1 h, then centrifuge at 8000 rpm for 4 min, take the precipitate, and redisperse it in 40 ml of deionized water to obtain the gold nanosphere colloidal solution.

[0053] For the preparation of the AuNS@Cu 2-x S core-shell heterostructured nanostructure: Take 5 ml of the obtained gold nanosphere colloidal solution, add 1 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 1 ml of a 0.1 mol / L hexamethylenetetramine solution, 1 ml of a 0.1 mol / L ascorbic acid solution, and a mixed solution of a certain amount of thioacetamide and copper nitrate solution, react in an 80 °C drying oven for 12 h, then centrifuge at 10000 rpm for 10 min, take the precipitate, and redisperse it in 10 ml of deionized water to obtain the AuNS@Cu 2-x S core-shell heterostructured nanostructure.

[0054] 1.1.3 MXene / Au NR@Cu 2-x Preparation of S interfacial photothermal conversion film

[0055] Compared with the MXene / Au NSR@Cu described in 1.1.1 above 2-x in the preparation of the S interfacial photothermal conversion film, except for the preparation of the gold seed solution, the preparation of the gold nanosphere colloidal solution and the preparation of Au NR@Cu 2-x S core-shell heterostructured nanostructures are different, the rest are the same as those described in 1.1.1 above.

[0056] Among them, the preparation of the gold seed solution: Prepare the gold seed solution and place it in the gold nanocolloid solution to obtain uniform gold nanospheres. Take 5 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 4.5 ml of deionized water solution, 500 μl of a 5 mmol / L chloroauric acid solution, and 600 μl of a 10 mmol / L sodium borohydride solution, place them on a magnetic stirrer for stirring reaction, the reaction time is 2 h, the rotation speed is 1400 revolutions / min, and the gold seed solution is obtained.

[0057] Preparation of gold nanorod colloidal solution: Take 80 μl of the gold seed solution obtained in step 1 and add it to a mixed solution of 30 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 6 ml of a 5 mmol / L chloroauric acid solution, 75 μl of a 0.1 mol / L silver nitrate solution, 90 μl of a 1.2 M hydrochloric acid solution, and 3.5 ml of a 10 mmol / L ascorbic acid solution. React in an incubator at 33 °C for 8 h, then centrifuge at 10000 revolutions / min for 10 min, take the precipitate, and redisperse it in 40 ml of deionized water to obtain the gold nanorod colloidal solution.

[0058] Preparation of AuNR@Cu 2-x S core-shell heterostructured nanostructure: Take 5 ml of the obtained gold nanosphere colloidal solution, add 1 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 1 ml of a 0.1 mol / L hexamethylenetetramine solution, 1 ml of a 0.1 mol / L ascorbic acid solution, and a certain amount of a mixed solution of thioacetamide and copper nitrate solution. React in a drying oven at 80 °C for 12 h, then centrifuge at 10000 revolutions / min for 10 min, take the precipitate, and redisperse it in 10 ml of deionized water to obtain AuNR@Cu 2-x S core-shell heterostructured nanostructure.

[0059] 1.1.4 MXene / Cu 2-x Preparation of S interfacial photothermal conversion film

[0060] Compared with the preparation of the MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film described in 1.1.1 above, except for the different preparation of the Cu 2-x S colloidal solution, the rest are the same as those described in 1.1.1 above.

[0061] Among them, the preparation of the Cu 2-x S colloidal solution: Mix 1 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 1 ml of a 0.1 mol / L hexamethylenetetramine solution, 1 ml of a 0.1 mol / L ascorbic acid solution, and a certain amount of a mixed solution of thioacetamide and copper nitrate solution, react in an 80 °C drying oven for 12 h, then centrifuge at 10,000 rpm for 10 min, take the precipitate, and redisperse it in 5 ml of deionized water to obtain the Cu 2-x S colloidal solution.

[0062] 1.1.5 Preparation of MXene / Au NR interfacial photothermal conversion film

[0063] Compared with the preparation of the MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film described in 1.1.1 above, except for the different preparation of the gold seed solution and the preparation of the gold nanorod colloidal solution, the rest are the same as those described in 1.1.1 above.

[0064] Among them, the preparation of the gold seed solution: Prepare the gold seed solution and place it in the gold nanocolloid solution to obtain uniform gold nanospheres. Take 5 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 4.5 ml of deionized water solution, 500 μl of a 5 mmol / L chloroauric acid solution, and 600 μl of a 10 mmol / L sodium borohydride solution, place them on a magnetic stirrer for stirring reaction, the reaction time is 2 h, and the rotation speed is 1400 rpm to obtain the gold seed solution.

[0065] Preparation of the gold nanorod colloidal solution: Take 80 μl of the gold seed solution obtained in step 1 and add it to a mixed solution of 30 ml of a 0.2 mol / L cetyltrimethylammonium bromide solution, 6 ml of a 5 mmol / L chloroauric acid solution, 75 μl of a 0.1 mol / L silver nitrate solution, 90 μl of a 1.2 M hydrochloric acid solution, and 3.5 ml of a 10 mmol / L ascorbic acid solution, react in a 33 °C incubator for 8 h, then centrifuge at 10,000 rpm for 10 min, take the precipitate, and redisperse it in 40 ml of deionized water to obtain the gold nanorod colloidal solution.

[0066] 1.2 Characterization

[0067] The MXene / Au NSR@Cu described in 1.1.1 above 2-x The photothermal conversion material MXene / Au NSR@Cu obtained in Step 4 of the preparation of the MXene / Au NSR@Cu 2-x S scanning electron microscopy results, as Figure 1 shown; the scanning electron microscopy of the photothermal conversion film (MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film) obtained in Step 5, as Figure 3 shown.

[0068] 2. Performance and application tests

[0069] A 300-watt xenon lamp equipped with a standard AM1.5 spectral optical filter was used as the light source for solar water evaporation testing (CEL-NP2000 high-intensity power meter calibrated to one sun); a power meter measured the solar radiation flux; an FLIR E4 infrared thermal imager was used to record the temperature of the interfacial photothermal conversion film; a laboratory balance controlled by a computer was used to monitor the change in water mass.

[0070] 2.1 High water evaporation rate and stability

[0071] The prepared MXene / Au NS@Cu 2-x S interfacial photothermal conversion film, MXene / Au NR@Cu 2-x S interfacial photothermal conversion film, MXene / Au NSR@Cu 2-x S (MXene / AuNR@Cu 2-x S / AuNS@Cu 2-x S) interfacial photothermal conversion film, MXene interfacial photothermal conversion film, MXene / Cu 2-x S interfacial photothermal conversion film, MXene / Au NR interfacial photothermal conversion film, with a hydrophilic cotton sheet as the blank control, where Au NR refers to Au nanorods, Au NS is Au nanospheres, and Au NSR is a mixture of Au nanorods and nanospheres, placed on the water surface of a container filled with water to make it stably float on the water surface. Under the light source condition of one sun power, the mass change was monitored by a laboratory balance controlled by a computer, and the effect is as Figures 4 - 6 shown.

[0072] It is Figure 4 shown that the evaporation rate of MXene / Au NSR@Cu 2-x S (MXene / AuNR@Cu 2-x S / AuNS@Cu 2-x S) is the highest.

[0073] Figure 5For the MXene / Au NSR@Cu of the present invention 2-x Control chart of the number of cycles and evaporation rate of the S material. It can be seen from Figure 5 that after 10 cycles (10 h), it still maintains 98% of the initial rate, indicating its good photothermal stability and durability.

[0074] Figure 6 For the water evaporation rate control chart of Mxene, M / Cus (Mxene / Cu 2-x S), M / Au (Mxene / AuNR), M / As@C (MXene / Au NS@Cu 2-x S), M / AR@C (MXene / Au NR@Cu 2-x S) and M / ASR@C (MXene / Au NSR@Cu 2-x S) under one sun condition. It can be seen from Figure 6 that the MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film has a light absorption rate of about 96% under one sun condition irradiation, and the best evaporation rate is 2.023 kg·m -2 ·h -1 .

[0075] In short, under the light source condition of one sun power, the water evaporation rate of the MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film is about 1.98 kg m -2 h -1 , and it still maintains 98% of the initial rate after 10 cycles (10 h), indicating good photothermal stability and durability. That is, the above measurement results of solar-driven water evaporation show that the MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film has great potential in water purification and seawater desalination; the MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film has a light absorption rate of about 96% under one sun condition irradiation, and the best evaporation rate is 2.023 kg·m -2 ·h -1 .

[0076] 2.2 Application in seawater desalination

[0077] To demonstrate the potential practical application of the above materials in seawater desalination, the prepared MXene / Au NSR@Cu 2-x S interfacial photothermal conversion film was placed above the liquid surface of a container filled with seawater. The seawater was treated using this interfacial photothermal conversion film under sunlight conditions. Through an ion chromatograph, we monitored Na + , Mg 2+, Ca 2+ and K + concentrations of four main ions. As Figure 7 shown, in the presence of the MXene / Au NSR@Cu 2-x S membrane, the concentrations of the four ions after desalination decreased by 3 - 4 orders of magnitude. And these concentrations are far lower than the safe salinity levels defined by the standards of the World Health Organization (WHO) and the US Environmental Protection Agency (EPA), meeting the drinking standards.

[0078] 2.3 Applications in pollution purification

[0079] In the application of treating polluted water, the prepared MXene / Au NSR@Cu 2-x S interfacial photothermal conversion membrane was respectively placed above the liquid surfaces of containers filled with rhodamine solution and methylene blue solution. Under daylight conditions, this interfacial photothermal conversion membrane was used to treat sewage. The absorbances of rhodamine and methylene blue in the solution were detected by a UV - 3600 ultraviolet - visible near - infrared spectrophotometer. As Figure 8 shown, the absorption peaks at 554 nm and 664 nm correspond to rhodamine and methylene blue respectively. These two peaks were almost completely eliminated after evaporation, indicating that this material has good water purification ability.

[0080] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above - mentioned terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0081] Although the embodiments of the present invention have been shown and described above, it can be understood that the above - mentioned embodiments are exemplary and should not be construed as limitations on the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above - mentioned embodiments within the scope of the present invention.

Claims

1. A highly efficient light-to-heat conversion material, characterized in that: The photothermal conversion material is MXene / Au@Cu 2-x S, 0<x<2, the MXene / Au@Cu 2-x S is composed of MXene nanosheets and Au@Cu 2-x The S core-shell heterogeneous material is obtained by chemical reaction, wherein the MXene nanosheets and the Au@Cu 2-x The molar ratio of the S core-shell heterogeneous material is 1:(0.1-1); The method for preparing an efficient photothermal conversion material comprises the following steps: firstly, MXene nanosheets and Au@Cu 2-x The S core-shell heterogeneous materials were mixed and then ultrasonically treated for 0.5 to 2 hours. The product obtained by ultrasonic treatment was centrifuged at 4000 to 7000 rpm / min for 2 to 10 minutes to obtain the photothermal conversion material MXene / Au@Cu 2-x S; The Au@Cu 2-x Preparation method of S core-shell heterogeneous material, comprising the following specific steps: Step 1, prepare a nano-gold colloidal solution: A mixed solution of chloroauric acid, cetyltrimethylammonium bromide, and sodium borohydride with a molar ratio of (0.03 - 0.1):(10 - 50):(3 - 6) is reacted at 30 - 40 °C for 0.5 - 2 h to obtain a gold seed solution; Then, chloroauric acid and cetyltrimethylammonium bromide are taken again according to the molar ratio of (3 - 10):1000, and after mixing, silver nitrate, hydrochloric acid, ascorbic acid, and the gold seed solution are added. The molar ratio of silver nitrate, hydrochloric acid, ascorbic acid, and the gold seed solution is (0.2 - 0.8):(5 - 12):(5 - 12):(0.02 - 0.18). After mixing again, the reaction is carried out overnight at room temperature. The reaction product obtained is centrifuged at 5000 - 10000 rpm for 5 - 15 min to obtain gold nanorods and / or nanospheres. The gold nanorods or nanospheres are dispersed in deionized water, and the molar ratio of the gold nanorods or nanospheres to deionized water is (5×10 -4 ~1×10 -3 ):1 to obtain a nano-gold colloidal solution; Step 2, Au@Cu 2-x Preparation of the S core-shell heterogeneous material: First, take ascorbic acid solution, cetyltrimethylammonium bromide, and hexamethylenetetramine according to the molar ratio of 0.1:1:0.1, mix them and add them to the nano-gold colloid solution to obtain a mixed solution; then add copper nitrate and thioacetamide solution to the mixed solution, and the molar ratio of the nano-gold colloid solution, copper nitrate to thioacetamide is 1:(0.5-2):(1-4), and then transfer it to an incubator at 95±2°C and place it for 6-10 h for reaction. Centrifuge the obtained reaction product at 5000-8000 rpm / min for 3-8 min to obtain the Au@Cu 2-x S core-shell heterogeneous material; The MXene nanosheets are Ti3C2T x ; The preparation method of the Ti3C2T x comprises the following specific steps: Slowly add lithium fluoride to hydrochloric acid, and the molar ratio of the lithium fluoride to the hydrochloric acid is 1:1 to form an HCI / LiF etching solution; Under stirring and an ice-water bath, slowly add Ti3AlC2 to the HCI / LiF etching solution, and the mass ratio of the Ti3AlC2 to the lithium fluoride is (1-5):(1-5). First, stir at room temperature for 1-2 h, then react at a temperature of 25-35 °C under stirring conditions for 20-28 h, and then centrifuge, wash, vacuum deoxidize, ultrasonicate under an ice-water bath condition, and vacuum dry the obtained reactants to obtain Ti3C2T x .

2. The high-efficiency light-to-heat conversion material according to claim 1, characterized in that: The Au@Cu 2-x S core-shell heterogeneous material includes Au NSR@Cu 2-x S core-shell heterogeneous material, Au NS@Cu 2-x S core-shell heterogeneous material, Au NR@Cu 2-x S core-shell heterogeneous material, or a combination of any one or at least two of them.

3. A photothermal conversion film, characterized in that, The photothermal conversion film comprises the photothermal conversion material MXene / Au@Cu as described in claim 1 or 2 2-x S, where 0 < x < 2.

4. The preparation method of a photothermal conversion film according to claim 3, characterized in that, including the following steps: adsorbing the photothermal conversion material MXene / Au@Cu 2-x S on a hydrophilic cotton sheet, and the molar ratio of the photothermal conversion material MXene / Au@Cu 2-x S to the hydrophilic cotton sheet is 1:(0.1-1) to obtain a photothermal conversion film.

5. Application of a photothermal conversion film, characterized in that, The photothermal conversion film as described in claim 3 is used for the desalination of seawater or the purification of sewage.

6. The application of a photothermal conversion film according to claim 5, wherein The photothermal conversion film is placed on the upper surface of the heat-insulating material wrapped with absorbent paper for the desalination of seawater or the purification of sewage.

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