Mesoporous gold-copper hollow ultrathin nanosheets and their preparation method and application

Abstract

The present invention relates to mesoporous gold-copper hollow ultrathin nanosheets, a preparation method thereof, and an application thereof. An organic amine, a quaternary ammonium salt surfactant, and a reducing agent are dissolved in water, a copper salt is added, and the reaction is carried out at a certain temperature for a period of time. The product is separated and purified by mechanical means and redispersed in water. An aqueous solution of a potassium salt, an organic acid, and a gold precursor is added to the prepared product, and the reaction is carried out at a certain temperature for a period of time. The product is separated and purified by mechanical means to obtain the final product. The present invention prepares gold-copper nanosheets by an oxidation etching means, and effectively regulates and controls the mesoporous structure and the sheet thickness of the gold-copper alloy nanomaterial, thereby improving its photothermal conversion performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy nanomaterials, and particularly relates to a mesoporous gold-copper hollow ultrathin nanosheet, a preparation method thereof, and an application thereof. Background Art

[0002] Alloy nanomaterials have always attracted much attention among various metal nanomaterials. Since there are two or more metals in a single alloy nanomaterial, a synergistic effect can be exerted, so they have important applications in the fields of catalysis, environmental science, biomedicine, energy, information technology, military equipment, aerospace, etc. For example: CN118455537A discloses a preparation method and application of a coral-shaped AuPd alloy nanomaterial, CN111804929A discloses a method for preparing a Pt-Cu nanosheet alloy in an aqueous phase, and CN115254140A discloses a noble metal-non-noble metal alloy nanomaterial and a synthesis method thereof. However, it is difficult to effectively control both the mesoporous structure and the sheet thickness of the existing alloy nanomaterials, thereby improving their performance.

[0003] Photothermal conversion materials are substances that can convert sunlight or other light sources into heat energy. They usually have a high light absorption rate and can effectively absorb light energy and convert it into heat energy. For example: CN113209307A discloses a doped Au&Ag alloy nano-covalent organic framework material, a preparation method thereof, and an application thereof. Gold-copper nanomaterials have good light absorption properties and are widely used in many fields such as electricity, magnetism, and catalysis. The preparation of gold-copper nanoalloys with a two-dimensional hollow structure has always been the research focus. How to effectively control the microstructure of gold-copper nanomaterials and improve their photothermal conversion performance is of great significance. For this reason, the present invention is proposed. Summary of the Invention

[0004] In view of the above-mentioned state of the prior art, the present invention provides a mesoporous gold-copper hollow ultrathin nanosheet, a preparation method thereof, and an application thereof.

[0005] The present invention prepares gold-copper nanosheets by means of oxidative etching, and effectively controls the mesoporous structure and the sheet thickness of the gold-copper alloy nanomaterials, thereby improving their photothermal conversion performance.

[0006] The technical solution of the present invention is as follows:

[0007] A preparation method of a mesoporous gold-copper hollow ultrathin nanosheet, comprising the following steps:

[0008] (1) Dissolve an organic amine, a quaternary ammonium salt surfactant, and a reducing agent in water, add a copper salt, react at a certain temperature for a period of time, separate and purify by mechanical means, and redisperse in water;

[0009] (2) Add an aqueous solution of a potassium salt, an organic acid, and a gold precursor to the product prepared in step (1), react for a period of time at a certain temperature, and separate and purify by mechanical means to obtain the final product.

[0010] According to the present invention, preferably, in step (1), the organic amine is one of oleylamine, hexadecylamine, dodecylamine, octadecylamine, hexamethylenetetramine, and most preferably hexamethylenetetramine.

[0011] According to the present invention, preferably, in step (1), the quaternary ammonium salt surfactant is one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, docosyltrimethylammonium bromide, docosyltrimethylammonium chloride, and most preferably cetyltrimethylammonium bromide.

[0012] According to the present invention, preferably, in step (1), the reducing agent is one of sodium borohydride, citric acid, ascorbic acid, hydrazine hydrate, and most preferably ascorbic acid.

[0013] According to the present invention, preferably, in step (1), the copper salt is one of copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetylacetonate, and most preferably copper nitrate.

[0014] According to the present invention, preferably, in step (1), the molar ratio of the organic amine, the quaternary ammonium salt surfactant, the reducing agent, and the copper salt is (1.8 - 3.2):(0.5 - 1.5):(1.2 - 3.5):1.

[0015] According to the present invention, preferably, in step (1), the range of the certain temperature is 10 - 95 °C, and more preferably 80 °C.

[0016] According to the present invention, preferably, in step (1), the range of the period of time is 0.5 - 10 hours, and more preferably 3 hours.

[0017] According to the present invention, preferably, in step (2), the potassium salt is one of potassium chloride, potassium bromide, potassium iodide, potassium sulfate, potassium nitrate, and more preferably potassium chloride.

[0018] According to the present invention, preferably, in step (2), the organic acid is one of formic acid, acetic acid, oxalic acid, and more preferably acetic acid.

[0019] According to the present invention, preferably, in step (2), the gold precursor is one of chloroauric acid, bromoauric acid, gold chloride, gold bromide, gold cyanide, and more preferably chloroauric acid.

[0020] According to the present invention, preferably, in step (2), the molar ratio of the potassium salt, the organic acid and the gold precursor is (30 - 2000):(1000 - 90000):1;

[0021] Preferably, the molar ratio of the copper salt in step (1) to the gold precursor in step (2) is (10 - 1500):1.

[0022] According to the present invention, preferably, in step (2), the range of the certain temperature is 10 - 95 °C, and more preferably 25 °C.

[0023] According to the present invention, preferably, in step (2), the range of the period of time is 0.5 - 10 hours, and more preferably 3 hours.

[0024] According to the present invention, preferably, in steps (1) and (2), the mechanical means is one of stirring, centrifugation, filtration, decantation, etc., and more preferably centrifugation.

[0025] According to the present invention, there is also provided a mesoporous gold - copper hollow ultrathin nanosheet obtained by the above - mentioned preparation method.

[0026] According to the present invention, there is also provided an application of the mesoporous gold - copper hollow ultrathin nanosheet obtained by the above - mentioned preparation method as a photothermal conversion material.

[0027] Advantages of the present invention:

[0028] 1. The preparation steps provided by the present invention are simple, the reactants are low - toxic and do not contain hazardous chemicals, water is used as a solvent, and the process is green and environmentally friendly;

[0029] 2. The present invention realizes the effective regulation of the mesoporous structure and the sheet thickness of the gold - copper nanosheet for the first time, expanding the limitations of the morphological structure of this material;

[0030] 3. The mesoporous gold - copper hollow ultrathin nanosheet prepared by the present invention can be used as a photothermal conversion material, and its porous structure and ultrathin structure are conducive to the reflection and effective absorption of incident light, and can provide good photothermal conversion efficiency. Description of the Drawings

[0031] Figure 1 It is a transmission electron microscope photograph of the product prepared in Example 1 of the present invention.

[0032] Figure 2 It is an X - ray diffraction pattern of the product prepared in Example 1 of the present invention.

[0033] Figure 3 It is an ultraviolet - visible absorption spectrum of the product prepared in Example 1 of the present invention and the suspension of the comparative samples (copper nanosheet, gold - copper nanosheet) in water.

[0034] Figure 4 Thermal imaging diagrams of the water suspensions of the product prepared in Example 1 of the present invention and comparative samples (copper nanosheets, gold-copper nanosheets) and water under laser irradiation over time.

[0035] Figure 5 Temperature curves of the water suspensions of the product prepared in Example 1 of the present invention and comparative samples (copper nanosheets, gold-copper nanosheets) and water under laser irradiation over time.

[0036] Figure 6 The time constant (τ) and conversion efficiency (η) of the system heat transfer determined by the linear time data of the water suspension of the product prepared in Example 1 of the present invention by applying a cooling cycle.

[0037] Figure 7 UV-visible absorption spectra of the water suspension of the product prepared in Example 1 of the present invention before and after laser irradiation. Detailed implementation manners

[0038] The present invention provides mesoporous gold-copper hollow ultrathin nanosheets, a preparation method thereof and applications. The preparation method of the mesoporous gold-copper hollow ultrathin nanosheets includes the following steps:

[0039] (1) Dissolve an organic amine, a quaternary ammonium salt surfactant, and a reducing agent in water, add a copper salt, react at a certain temperature for a period of time, separate and purify by mechanical means, and redisperse in water;

[0040] (2) Add an aqueous solution of a potassium salt, an organic acid, and a gold precursor to the product prepared in step (1), react at a certain temperature for a period of time, separate and purify by mechanical means to obtain the final product.

[0041] According to the present invention, in step (1), the organic amine functions as a structure-directing agent.

[0042] In one or more preferred embodiments, the organic amine is one of oleylamine, hexadecylamine, dodecylamine, octadecylamine, hexamethylenetetramine, and most preferably hexamethylenetetramine.

[0043] According to the present invention, in step (1), the quaternary ammonium salt surfactant functions as a capping agent on the surface of the copper nanosheets.

[0044] In one or more preferred embodiments, the quaternary ammonium salt surfactant is one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, docosyltrimethylammonium bromide, docosyltrimethylammonium chloride, and most preferably cetyltrimethylammonium bromide.

[0045] According to the present invention, in step (1), the reducing agent functions to reduce divalent copper ions to zero-valent copper.

[0046] In one or more preferred embodiments, the reducing agent is one of sodium borohydride, citric acid, ascorbic acid, and hydrazine hydrate, and is most preferably ascorbic acid.

[0047] In one or more preferred embodiments, the copper salt in step (1) is one of copper chloride, copper bromide, copper sulfate, copper nitrate, and copper acetylacetonate, and most preferably copper nitrate.

[0048] In one or more preferred embodiments, in step (1), the molar ratio of the organic amine, the quaternary ammonium salt surfactant, the reducing agent, and the copper salt is (1.8-3.2):(0.5-1.5):(1.2-3.5):1.

[0049] In one or more preferred embodiments, the certain temperature in step (1) is in the range of 10-95°C, more preferably 80°C.

[0050] In one or more preferred embodiments, the period of time in step (1) ranges from 0.5 to 10 hours, more preferably 3 hours.

[0051] In one or more preferred embodiments, the potassium salt in step (2) is one of potassium chloride, potassium bromide, potassium iodide, potassium sulfate and potassium nitrate, and more preferably potassium chloride.

[0052] According to the present invention, in step (2), the function of the organic acid is to oxidize and etch part of the copper element into monovalent or divalent copper.

[0053] In one or more preferred embodiments, the organic acid is one of formic acid, acetic acid and oxalic acid, and more preferably acetic acid.

[0054] In one or more preferred embodiments, the gold precursor in step (2) is one of chloroauric acid, bromoauric acid, gold chloride, gold bromide, and gold cyanide, and chloroauric acid is more preferably used.

[0055] In one or more preferred embodiments, the molar ratio of the potassium salt, the organic acid and the gold precursor in step (2) is (30-2000): (1000-90000): 1;

[0056] Preferably, the molar ratio of the copper salt in step (1) to the gold precursor in step (2) is (10-1500):1.

[0057] In one or more preferred embodiments, the certain temperature in step (2) is in the range of 10-95°C, more preferably 25°C.

[0058] In one or more preferred embodiments, the range of the period of time in step (2) is 0.5 - 10 hours, and more preferably 3 hours.

[0059] In one or more preferred embodiments, in steps (1) and (2), the mechanical means is one of stirring, centrifugation, filtration, decantation, etc., and more preferably centrifugation.

[0060] The present invention effectively regulates the mesoporous structure and the sheet thickness of the gold - copper alloy nanomaterial through an oxidation etching means. The present invention realizes the regulation of the mesopore diameter size by controlling the addition ratio of chloroauric acid. As the addition ratio of chloroauric acid increases, the mesopore diameter shows an increasing trend; the effective control of the sheet thickness is realized by controlling the reaction time or the addition ratio of the acid. As the reaction time increases and the addition ratio of the acid increases, the thickness of the obtained nanosheets shows a decreasing trend.

[0061] According to the present invention, there is also provided a mesoporous gold - copper hollow ultrathin nanosheet obtained by the above - mentioned preparation method.

[0062] In one or more preferred embodiments, the mesopore size of the mesoporous gold - copper hollow ultrathin nanosheet is 4.0 - 11.0 nm, and the nanosheet thickness is 7.0 - 15.0 nm.

[0063] According to the present invention, there is also provided the application of the mesoporous gold - copper hollow ultrathin nanosheet obtained by the above - mentioned preparation method as a photothermal conversion material.

[0064] Example 1

[0065] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 100 mL of water, add 0.5 g of copper nitrate, and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 0.5 g of potassium chloride, 20.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0066] Example 2

[0067] Dissolve 4.8 g of oleylamine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 100 mL of water, add 0.5 g of copper nitrate, and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 0.5 g of potassium chloride, 20 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0068] Example 3

[0069] Dissolve 2.0 g of octadecylamine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 100 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 0.5 g of potassium chloride, 20 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0070] Example 4

[0071] Dissolve 0.5 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium chloride, and 0.7 g of ascorbic acid in 60 mL of water. Add 0.6 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 50 mL of water. Then continue to add 0.2 g of potassium chloride, 1 g of acetic acid, and 1 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0072] Example 5

[0073] Dissolve 0.1 g of hexamethylenetetramine, 0.1 g of octadecyltrimethylammonium bromide, and 0.3 g of ascorbic acid in 15 mL of water. Add 0.1 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 10 mL of water. Then continue to add 0.06 g of potassium chloride, 1.0 g of acetic acid, and 0.02 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0074] Example 6

[0075] Dissolve 1.0 g of hexamethylenetetramine, 1.2 g of cetyltrimethylammonium bromide, and 0.5 g of sodium borohydride in 100 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 0.5 g of potassium chloride, 20 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0076] Example 7

[0077] Dissolve 0.2 g of hexamethylenetetramine, 0.2 g of cetyltrimethylammonium bromide, and 0.2 g of citric acid in 30 mL of water. Add 0.1 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 30 mL of water. Then continue to add 0.1 g of potassium chloride, 4.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0078] Example 8

[0079] Dissolve 0.4 g of hexamethylenetetramine, 0.4 g of cetyltrimethylammonium bromide, and 0.4 g of ascorbic acid in 70 mL of water. Add 0.2 g of copper chloride and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 40 mL of water. Then continue to add 0.2 g of potassium chloride, 6.0 g of acetic acid, and 5 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0080] Example 9

[0081] Dissolve 0.6 g of hexamethylenetetramine, 0.6 g of cetyltrimethylammonium bromide, and 0.7 g of ascorbic acid in 80 mL of water. Add 0.3 g of copper sulfate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 70 mL of water. Then continue to add 0.2 g of potassium chloride, 7.0 g of acetic acid, and 1 mL of an aqueous solution of chloroauric acid with a concentration of 50 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0082] Example 10

[0083] Dissolve 3.0 g of hexamethylenetetramine, 3.0 g of cetyltrimethylammonium bromide, and 5.5 g of ascorbic acid in 500 mL of water. Add 1.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 300 mL of water. Then continue to add 0.3 g of potassium chloride, 30 g of acetic acid, and 6 mL of an aqueous solution of chloroauric acid with a concentration of 50 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0084] Example 11

[0085] Dissolve 1.0 g of hexamethylenetetramine, 0.6 g of cetyltrimethylammonium bromide, and 0.9 g of ascorbic acid in 30 mL of water. Add 0.3 g of copper nitrate and react at 10 °C for 3 hours. Purify by centrifugation and redisperse in 30 mL of water. Then continue to add 0.1 g of potassium chloride, 2.0 g of acetic acid, and 0.3 mL of an aqueous solution of chloroauric acid with a concentration of 10 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0086] Example 12

[0087] Dissolve 1.5 g of hexamethylenetetramine, 1.5 g of cetyltrimethylammonium bromide, and 1.5 g of ascorbic acid in 200 mL of water. Add 0.7 g of copper nitrate and react at 95 °C for 3 hours. Purify by centrifugation and redisperse in 15 mL of water. Then continue to add 1.0 g of potassium chloride, 2.0 g of acetic acid, and 0.3 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0088] Example 13

[0089] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 150 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 0.5 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 0.3 g of potassium chloride, 3.5 g of acetic acid, and 1 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0090] Example 14

[0091] Dissolve 5.0 g of hexamethylenetetramine, 3.0 g of cetyltrimethylammonium bromide, and 3.0 g of ascorbic acid in 500 mL of water. Add 1.5 g of copper nitrate and react at 80 °C for 10 hours. Purify by centrifugation and redisperse in 300 mL of water. Then continue to add 1.0 g of potassium chloride, 60.0 g of acetic acid, and 9 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0092] Example 15

[0093] Dissolve 0.5 g of hexamethylenetetramine, 0.6 g of cetyltrimethylammonium bromide, and 0.6 g of ascorbic acid in 60 mL of water. Add 0.3 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 60 mL of water. Then continue to add 0.2 g of potassium bromide, 6.0 g of acetic acid, and 0.6 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0094] Example 16

[0095] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 150 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 1.2 g of potassium sulfate, 20.0 g of acetic acid, and 1.5 mL of an aqueous solution of chloroauric acid with a concentration of 50 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0096] Example 17

[0097] Dissolve 3.5 g of hexamethylenetetramine, 2.5 g of cetyltrimethylammonium bromide, and 3.0 g of ascorbic acid in 500 mL of water. Add 1.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 300 mL of water. Then continue to add 1.2 g of potassium chloride, 50.0 g of formic acid, and 3 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0098] Example 18

[0099] Dissolve 2.0 g of hexamethylenetetramine, 2.0 g of cetyltrimethylammonium bromide, and 2.0 g of ascorbic acid in 300 mL of water. Add 1.0 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 200 mL of water. Then continue to add 0.7 g of potassium chloride, 30.0 g of oxalic acid, and 1.5 mL of an aqueous solution of chloroauric acid with a concentration of 50 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0100] Example 19

[0101] Dissolve 10.0 g of hexamethylenetetramine, 10.0 g of cetyltrimethylammonium bromide, and 11.0 g of ascorbic acid in 1000 mL of water. Add 5.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 1000 mL of water. Then continue to add 30.0 g of potassium chloride, 800.0 g of acetic acid, and 40 mL of an aqueous solution of chloroauric acid with a concentration of 50 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0102] Example 20

[0103] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 150 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 1.0 g of potassium sulfate, 20.0 g of acetic acid, and 1 mL of an aqueous solution of bromoauric acid with a concentration of 50 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0104] Example 21

[0105] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 150 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 50 mL of water. Then continue to add 0.3 g of potassium chloride, 20.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 10 mM, and react at 10 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0106] Example 22

[0107] Dissolve 0.8 g of hexamethylenetetramine, 0.8 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 120 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 50 mL of water. Then continue to add 0.6 g of potassium chloride, 15.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 95 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0108] Example 23

[0109] Dissolve 1.2 g of hexamethylenetetramine, 1.6 g of cetyltrimethylammonium bromide, and 1.2 g of ascorbic acid in 120 mL of water. Add 0.4 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 40 mL of water. Then continue to add 1.0 g of potassium chloride, 25.0 g of acetic acid, and 0.2 mL of an aqueous solution of chloroauric acid with a concentration of 10 mM, and react at 25 °C for 0.5 hour. Purify by centrifugation to obtain the final product.

[0110] Example 24

[0111] Dissolve 0.2 g of hexamethylenetetramine, 0.2 g of cetyltrimethylammonium bromide, and 0.2 g of ascorbic acid in 30 mL of water. Add 0.1 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 20 mL of water. Then continue to add 0.1 g of potassium chloride, 10.0 g of acetic acid, and 0.2 mL of an aqueous solution of chloroauric acid with a concentration of 10 mM, and react at 25 °C for 10 hours. Purify by centrifugation to obtain the final product.

[0112] Example 25

[0113] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 150 mL of water. Add 0.4 g of copper nitrate and react at 80 °C for 3 hours. Purify by decantation and redisperse in 80 mL of water. Then continue to add 0.2 g of potassium chloride, 5.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 10 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0114] Example 26

[0115] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 150 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by filtration and redisperse in 100 mL of water. Then continue to add 0.3 g of potassium chloride, 20.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by centrifugation to obtain the final product.

[0116] Example 27

[0117] Dissolve 0.5 g of hexamethylenetetramine, 0.5 g of cetyltrimethylammonium bromide, and 1.0 g of ascorbic acid in 150 mL of water. Add 0.5 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 0.3 g of potassium chloride, 20.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 20 mM, and react at 25 °C for 3 hours. Purify by decantation to obtain the final product.

[0118] Example 28

[0119] Dissolve 1.0 g of hexamethylenetetramine, 1.0 g of cetyltrimethylammonium bromide, and 1.5 g of ascorbic acid in 150 mL of water. Add 1.0 g of copper nitrate and react at 80 °C for 3 hours. Purify by centrifugation and redisperse in 100 mL of water. Then continue to add 1.2 g of potassium chloride, 30.0 g of acetic acid, and 2 mL of an aqueous solution of chloroauric acid with a concentration of 50 mM, and react at 25 °C for 3 hours. Purify by filtration to obtain the final product.

[0120] Test Example 1

[0121] Test the transmission electron microscope photograph of the final product prepared in Test Example 1, as Figure 1 shown. It can be seen from Figure 1 that the mesopore size of the mesoporous gold-copper hollow ultrathin nanosheets is 4.0 - 11.0 nm, and the thickness of the nanosheets is 7.0 - 15.0 nm.

[0122] Test Example 2

[0123] Test the X-ray diffraction pattern of the mesoporous gold-copper hollow ultrathin nanosheets, the final product prepared in Test Example 1. As Figure 2 shown. It can be seen from Figure 2 that by comparing with the Au and Cu standard PDF cards, the crystal structure of the mesoporous gold-copper hollow ultrathin nanosheets is composed of a copper face-centered cubic structure and a gold-copper alloy face-centered cubic structure. Through the test of the EDS elemental composition, the copper / gold atomic ratio is obtained as 2 / 1.

[0124] Test Example 3

[0125] Test the ultraviolet-visible absorption spectrum of the mesoporous gold-copper hollow ultrathin nanosheets, the final product prepared in Test Example 1. As Figure 3 shown. It can be seen from Figure 3 that the aqueous suspension of the gold-copper hollow ultrathin nanosheets has a strong absorbance at a wavelength of 800 - 1100 nm. The comparison samples are gold-copper nanosheets and copper nanosheets, which have no mesopores and a thickness dozens of times that of the gold-copper hollow ultrathin nanosheets.

[0126] Test Example 4

[0127] Test the photothermal conversion performance of the final product, mesoporous gold-copper hollow ultrathin nanosheets, prepared in Example 1, as shown in Figure 4 , 5, 6, and 7. Use a laser with a wavelength of 808 nm and a power density of 1 W / cm 2 to irradiate the aqueous suspension of mesoporous gold-copper hollow ultrathin nanosheets. As can be seen from Figure 4 , as the laser irradiation time increases, the temperature of the sample suspension gradually rises. As can be seen from Figure 5 , after 10 minutes of irradiation, the temperature of the gold-copper hollow ultrathin nanosheet suspension increases from 23 °C to 48 °C. Compared with the comparative samples of gold-copper nanosheets, copper nanosheets, and water, the suspension of the product of the present invention has a faster heating rate after laser irradiation and can reach a higher temperature in 10 minutes. As can be seen from Figure 6 , the photothermal conversion efficiency (η) of the mesoporous gold-copper hollow ultrathin nanosheets is 59.4%. As can be seen from Figure 7 , the absorbance of the mesoporous gold-copper hollow ultrathin nanosheets slightly increases before and after laser irradiation, indicating good stability in the laser irradiation environment.

Claims

1. A method for preparing mesoporous gold-copper hollow ultrathin nanosheets, comprising the following steps: (1) Dissolve the organic amine, quaternary ammonium salt surfactant and reducing agent in water, add copper salt and heat at 10-95 o C for 0.5-10 hours, separated and purified by mechanical means, and redispersed in water; (2) Add potassium salt, organic acid and aqueous solution of gold precursor to the product prepared in step (1) at 10-95 o The reaction is carried out at a temperature of C for 0.5-10 hours, and separation and purification are carried out by mechanical means to obtain mesoporous gold-copper hollow ultrathin nanosheets. The mesopore size of the mesoporous gold-copper hollow ultrathin nanosheets is 4.0-11.0 nm, and the thickness of the nanosheets is 7.0-15.0 nm.

2. The method for preparing the mesoporous gold-copper hollow ultrathin nanosheet according to claim 1, characterized in that: In step (1), the organic amine is one of oleylamine, hexadecylamine, dodecylamine, octadecylamine, and hexamethylenetetramine; the quaternary ammonium salt surfactant is one of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, behenyltrimethylammonium bromide, and behenyltrimethylammonium chloride; and the reducing agent is one of sodium borohydride, citric acid, ascorbic acid, and hydrazine hydrate.

3. The method for preparing the mesoporous gold-copper hollow ultrathin nanosheet according to claim 1, characterized in that: In step (1), the copper salt is one of copper chloride, copper bromide, copper sulfate, copper nitrate, and copper acetylacetonate.

4. The method for preparing the mesoporous gold-copper hollow ultrathin nanosheet according to claim 1, characterized in that: In step (1), the molar ratio of the organic amine, the quaternary ammonium salt surfactant, the reducing agent and the copper salt is (1.8-3.2):(0.5-1.5):(1.2-3.5):

1.

5. The method for preparing the mesoporous gold-copper hollow ultrathin nanosheet according to claim 1, characterized in that: In step (2), the potassium salt is one of potassium chloride, potassium bromide, potassium iodide, potassium sulfate, and potassium nitrate; the organic acid is one of formic acid, acetic acid, and oxalic acid; and the gold precursor is one of chloroauric acid, bromoauric acid, gold chloride, gold bromide, and gold cyanide.

6. The method for preparing the mesoporous gold-copper hollow ultrathin nanosheet according to claim 1, characterized in that: The molar ratio of potassium salt, organic acid and gold precursor in step (2) is (30-2000):(1000-90000):1, and the molar ratio of copper salt in step (1) to gold precursor in step (2) is (10-1500):

1.

7. A mesoporous gold-copper hollow ultrathin nanosheet, characterized in that: The mesoporous gold-copper hollow ultrathin nanosheet is prepared according to any one of the preparation methods of claims 1-6.

8. Application of mesoporous gold-copper hollow ultrathin nanosheets as photothermal conversion materials, characterized in that: The mesoporous gold-copper hollow ultrathin nanosheet is prepared according to any one of the preparation methods of claims 1-6.

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