A gold-silver nanoarray material and its preparation method and use

Abstract

The present invention relates to the field of binary precious metal nanomaterials, and in particular to a gold-silver nanoarray and its preparation method and pattern anti-counterfeiting application. After sputtering and depositing a gold film on a monolayer polystyrene microsphere template, the present invention obtains a gold nanosphere array by high-temperature calcination, and then uses AMBI to modify the surface of the gold nanosphere array. The AMBI ligand is anchored to the surface of the gold nanosphere through the Au-S bond, so that the interface energy on the surface of the gold nanosphere is increased, helping silver ions to overcome the electrostatic potential well resistance between the substrate (Si) and the gold nanosphere and nucleate and further grow on the surface of the gold nanosphere. By changing the type of reducing agent, the morphology of silver nanoparticles is regulated to obtain gold-silver nanoarrays with different silver nanoparticle morphologies. The gold-silver nanoarray prepared by the present invention can be used as an information carrier in fields such as information anti-counterfeiting. The present invention solves the technical problems of high cost, difficult directional control, and complex reaction kinetics of existing gold-silver nanoarray material preparation methods.

Description

Technical Field

[0001] The present invention relates to the field of binary noble metal nanomaterials, and in particular to a gold-silver nanoarray material, a preparation method thereof, and uses thereof. Background Art

[0002] Information carriers based on optical effects have the advantages of large capacity, multi-dimensionality, and high safety factor, and can be used to cope with today's fast, frequent, and complex information transmission. The special LSPR properties and periodic structure of plasma (Au, Ag, etc.) nanoarrays give them excellent optical properties. By utilizing the selective absorption and scattering of light by monomer units and dimer units in plasma nanoarrays, a patterned plasma array can be formed. It is gaining more and more attention as an information carrier in the fields of information storage / encryption, optical communication chips, etc. According to the plasma exciton coupling model, when other parameters are consistent, the energy level difference between heterogeneous dimers and monomers is greater than the energy level difference between homogeneous dimers and monomers. Therefore, the color contrast between heterogeneous dimers and monomers is higher, which is conducive to achieving high-resolution information expression. However, at this stage, there are still challenges in the high-precision, controllable, and large-area preparation of patterned heterogeneous plasma nanoarrays.

[0003] Currently, the controllable preparation of heterogeneous plasmon dimer arrays can be divided into two main methods: 1. Traditional "top-down" strategies, such as dip pen lithography, laser direct writing, and physical vapor deposition. This type of method has good long-range order and high repeatability, but the equipment cost is high, the energy consumption is large, the operation is complex, and large-scale manufacturing is difficult; 2. "Bottom-up" self-assembly strategy, which mostly relies on electrostatic forces, capillary forces, etc., such as inkjet printing, template-assisted convection assembly, etc. The assembly materials are abundant and the yield is higher than the former, but the experimental environment and assembly conditions are demanding, and the assembled arrays are mostly homogeneous plasmon dimer arrays. The pattern resolution is mostly in the micrometer range, and the assembly of heterogeneous plasmon dimer arrays remains a challenge. Therefore, it is necessary to develop a simple, controllable method for preparing heterogeneous plasmon dimer arrays on a large scale, and to pattern them to achieve high-resolution information display. Summary of the Invention

[0004] One of the objectives of the present invention is to provide a method for preparing a gold-silver nanoarray material. The method comprises sputtering and depositing a gold film on a monolayer polystyrene microsphere template, followed by high-temperature calcination to obtain a gold nanosphere array. The material is then modified using 5-amino-2-mercaptobenzimidazole (AMBI), and after adding a precursor and a reducing agent solution, the mixture is thoroughly mixed and reacted to obtain a gold-silver nanoarray material. Alternatively, a patterned gold-silver nanoarray material can be prepared by combining it with electron beam lithography. By varying the type of reducing agent, the morphology of the silver nanoparticles can be regulated to obtain gold-silver nanoarrays with different silver nanoparticle morphologies. The material has diverse structures and rich coupling mode variations, resulting in fine color control and achieving nanometer-scale resolution for the patterned gold-silver heterodimer array. This solves the technical problems of prior art methods for preparing gold-silver nanoarray materials, such as high cost, difficulty in directional control, and low patterning resolution.

[0005] To achieve the above object, the present invention adopts the following technical solution: a method for preparing a gold-silver nanoarray material, comprising the following steps:

[0006] Step A: preparing a monolayer polystyrene microsphere template with an orderly arrangement of polystyrene microspheres having a uniform diameter of 350-2000 nm, and transferring the monolayer polystyrene microsphere template to a silicon wafer surface to obtain a silicon wafer having a monolayer polystyrene microsphere template;

[0007] Step B, sputtering and depositing a gold film on the surface of the silicon wafer where the monolayer of polystyrene microspheres is located, and annealing at 1000-1100° C. for 2-3 hours to obtain a gold nanosphere array with a diameter of 180-500 nm;

[0008] Step C, placing the gold nanosphere array in a thiol-containing ligand solution for modification, then adding a silver nitrate solution and a reducing agent solution, reacting at 15-30° C. for 5-50 minutes, and finally preparing a gold-silver nanosphere array material;

[0009] Alternatively, a photoresist film is spin-coated on the surface of the gold nanosphere array, baked and cured, and then a pattern is depicted using electron beam lithography technology. After exposure, development and fixing, a patterned area of the silver nanostructure is obtained. The gold nanosphere array on the patterned surface not covered by the photoresist is placed in a thiol-containing ligand solution for modification. Then, a silver nitrate solution and a reducing agent solution are added, and the reaction is carried out at 15-30° C. for 5-50 minutes. The photoresist film is removed to obtain a patterned gold-silver nanoarray material.

[0010] Further improvement of the preparation method of gold-silver nanoarray materials:

[0011] Preferably, in step A, a liquid surface self-assembly method is used to prepare an orderly arranged single-layer polystyrene microsphere on a glass slide to obtain a single-layer polystyrene microsphere template, and then the single-layer polystyrene microsphere template is transferred to the silicon wafer surface by a liquid surface floating ball scooping method.

[0012] Preferably, the surfaces of the glass slide and silicon wafer are cleaned with acetone, ethanol, piranha solution and deionized water to remove organic matter on the surface, and then cleaned with an ultraviolet ozone cleaner for 10-30 minutes to make the surface hydrophilic.

[0013] Preferably, in step B, a fully automatic ion sputtering coating apparatus is used for sputtering deposition, the current of the sputtering deposition is 10-20 mA, and the sputtering time is 8-3 min.

[0014] Preferably, the thiol-containing ligand in step C is one of 5-amino-2-mercaptobenzimidazole and 2-mercaptobenzimidazole carboxylic acid, with a concentration of 1-100 μmol / L; the reducing agent in the reducing agent solution is one of hydroquinone, ascorbic acid, sodium borohydride, glucose, sodium citrate and sodium hypophosphite.

[0015] Preferably, the temperature for modification in step C is 40-80°C.

[0016] Preferably, the type of the photoresist in step C is one of AR-P617PMMA / MA copolymer, PMMA and negative resist, and the molecular weight of the photoresist is one of 200K, 400K, 600K and 950K.

[0017] Preferably, in step C, the silver nitrate solution and the reducing agent solution are added to the system so that the concentration of silver nitrate is 0.05-0.6 mmol / L and the concentration of the reducing agent is 0.05-0.6 mmol / L.

[0018] A second object of the present invention is to provide a gold-silver nanoarray material prepared by any of the above-mentioned methods for preparing the gold-silver nanoarray material.

[0019] The third object of the present invention is to provide a use of the above-mentioned gold-silver nanoarray material as an information carrier in the field of information anti-counterfeiting.

[0020] The beneficial effects of the present invention compared to the prior art are:

[0021] 1) The present invention provides a gold-silver nanoarray material, wherein the structural units of the material have uniform morphology, uniform size, and are arranged periodically. Each gold-silver nanostructure unit contains gold and silver of specific sizes. By changing the type of reducing agent, gold-silver nanoarray materials containing different silver morphologies are obtained. By changing the morphology of silver nanoparticles and regulating the plasma coupling between gold and silver, the material structure is diverse and has rich coupling mode changes, achieving selective absorption and scattering of incident light, so that the color of the patterned gold-silver array is finely regulated, and the information resolution of the patterned gold-silver heterodimer array reaches the nanometer level. The gold-silver nanoarray material has better photostability than traditional fluorescent materials, which is beneficial for its application in the field of information anti-counterfeiting.

[0022] 2) The present invention provides a method for synthesizing gold-silver nanoarray materials. Compared with traditional "top-down" and "bottom-up" self-assembly strategies, this method has lower cost, simple operation process, fast reaction speed, high yield, and can be prepared on a large scale. Gold nanosphere arrays with a period of 350-2000nm and a diameter of 180-500nm are synthesized using a colloidal sphere template method. The surface of the gold nanosphere array is then modified using 5-amino-2-mercaptobenzimidazole, and the AMBI ligand is anchored to the surface of the gold nanospheres through Au-S bonds, thereby increasing the interfacial energy on the surface of the gold nanospheres. The increased interfacial energy helps silver ions overcome the electrostatic potential well resistance between the substrate (Si) and the gold nanospheres, nucleating and further growing on the surface of the gold nanospheres. By changing the type of reducing agent, the morphology of the silver nanoparticles can be controlled to obtain gold-silver nanoarrays with different morphologies. At the same time, combined with electron beam lithography technology, patterned gold-silver nanoarray materials can be produced.

[0023] 3) The method for preparing the gold-silver nanoarray material provided by the present invention requires only a drying oven, an ion sputtering coater, a muffle furnace, and a glass bottle, thus requiring relatively low equipment requirements. The process is simple, easy to operate, low-cost, and high-yield, and can be developed into a universal synthesis strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. The drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0025] Figure 1 (a) and (b) are scanning electron microscope photos and particle size statistics of the gold nanosphere array 1 prepared in Example 1 of the present invention, respectively.

[0026] Figure 2(a) and (b) are scanning electron microscope photos and particle size statistics of the gold nanosphere array 2 prepared in Example 1 of the present invention, respectively.

[0027] Figure 3 This is a scanning electron microscope photograph of the gold-silver nanoarray material 1 prepared in Example 1 of the present invention.

[0028] Figure 4 These are Raman spectra of the gold nanosphere array 1, the modified gold nanosphere array 1, and the gold-silver nanoarray material 1 prepared in Example 1 of the present invention.

[0029] Figure 5 Transmission electron microscope photograph of the structural unit of the gold-silver nanoarray material 1 prepared in Example 1 of the present invention and the surface distribution map (EDX mapping) of gold, silver, sulfur and nitrogen elements.

[0030] Figure 6 This is a scanning electron microscope photograph of the gold-silver nanoarray material 2 prepared in Example 2 of the present invention.

[0031] Figure 7 (a)-(b) are scanning electron microscope photos of the patterned gold-silver nanoarray material 3 prepared in Example 3 of the present invention and the patterned gold-silver nanoarray material 4 prepared in Example 4, respectively.

[0032] Figure 8 (a)-(b) are dark field optical photographs of the patterned gold-silver nanoarray material 3 prepared in Example 3 of the present invention and the patterned gold-silver nanoarray material 4 prepared in Example 4. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing a gold-silver nanoarray material, comprising the following steps:

[0036] Step A: Clean the glass slide and silicon wafer surfaces with acetone, ethanol, piranha solution, and deionized water to remove organic matter on the surface, and then use a UV-ozone cleaner to clean for 20 minutes to make the surface hydrophilic.

[0037] Polystyrene microspheres with a uniform diameter of 500 nm were used to prepare a monolayer of polystyrene microspheres on a glass slide using a liquid surface self-assembly method. The monolayer of polystyrene microspheres was then transferred to a silicon wafer using a liquid surface floating ball scooping method, resulting in a silicon wafer with a monolayer of polystyrene microspheres with a diameter of 500 nm.

[0038] Similarly, polystyrene microspheres with a diameter of 1000 nm and uniform size were taken and, referring to the above steps, a silicon wafer with a single layer of polystyrene microspheres with a diameter of 1000 nm was prepared;

[0039] Step B: using a fully automatic ion sputtering coating apparatus with a current of 20 mA and a sputtering time of 210 s, a gold film approximately 200 nm thick was sputter-deposited on the surface of a silicon wafer containing a single layer of polystyrene microspheres with a diameter of 500 nm. The film was annealed at 1000° C. for 2 h to obtain a gold nanosphere array 1 with a center-to-center distance of 500 nm and a gold nanosphere diameter of 190 nm.

[0040] At the same time, a fully automatic ion sputtering coating apparatus was used with a current of 20 mA and a sputtering time of 210 s to sputter-deposit a layer of gold film on the surface of a silicon wafer microsphere with a single layer of polystyrene microspheres with a diameter of 1000 nm. The film was annealed at 1000°C for 2 h to obtain a gold nanosphere array with a center distance of 1000 nm and a gold nanosphere diameter of 300 nm.

[0041] Step C: At 50°C, the gold nanosphere array 1 is placed in a 5 μmol / L 5-amino-2-mercaptobenzimidazole ligand solution for modification, and then a silver nitrate solution and a hydroquinone solution are added to the system until the concentration of silver nitrate is 0.3 mmol / L and the concentration of hydroquinone is 0.3 mmol / L; then, the system is placed in a 25°C reaction for 30 minutes and then taken out to finally obtain a gold-silver nanoplate array material 1 with a period of 500 nm.

[0042] The intermediate product and the final product of Example 1 were subjected to the following morphology and performance tests:

[0043] (1) Using a scanning electron microscope, the gold nanosphere array 1 and the gold nanosphere array 2 prepared in Example 1 were observed and photographed, and the particle size statistics were performed; the gold-silver nanoarray material 1 was observed and photographed; the scanning image and particle size statistics of the gold nanosphere array 1 are shown in FIG. Figure 1 As shown, the scanning image and particle size statistics of the gold nanosphere array 2 are shown in FIG. Figure 2 As shown, the scanning electron microscope image of the gold-silver nanoarray material 1 is as follows Figure 3 As shown. Figure 1 、 2It can be seen that the gold nanosphere array material 1 with a period of 500nm and a gold nanosphere particle size of 190nm was prepared on a large area, and the gold nanosphere array material 2 with a period of 1000nm and a gold nanosphere particle size of 300nm was prepared on a large area. Figure 3 It can be seen that the gold-silver nanoplate array material 1 is prepared on a large scale. It is composed of orderly arranged gold-silver nanostructure units. The silver nanostructure is plate-shaped. The gold-silver nanoplate array structural units have uniform morphology, uniform size, and are arranged periodically.

[0044] (2) Raman spectroscopy was performed on the gold nanosphere array 1, the modified gold nanosphere array 1 and the gold-silver nanoplate array material 1 prepared above. The results are as follows: Figure 4 As shown. Figure 4 It can be seen that the 5-amino-2-mercaptobenzimidazole ligand was successfully adsorbed on the surface of gold nanospheres.

[0045] The transmission electron micrographs of the structural unit of the gold-silver nanoplate array material 1 and the surface distribution of gold, silver, sulfur, and nitrogen elements were observed using a Tecnai G2 F20 high-resolution transmission electron microscope. Figure 5 As shown. Figure 4 and Figure 5 It can be seen that after the growth of silver nanoplates, the ligands are still adsorbed on the surface of the gold-silver nanoplate array.

[0046] Example 2

[0047] This embodiment provides a method for preparing a gold-silver nanoarray material. The specific steps are similar to those of Example 1, except that ascorbic acid is added as the reducing agent in step C. The other steps are the same as those for preparing the gold nanosphere array 1 and the gold-silver nanoplate array material 1 in Example 1, ultimately producing a gold-silver nanocube array material 2.

[0048] The gold-silver nanocube array material 2 prepared in Example 2 was observed and photographed using a scanning electron microscope to obtain Figure 6 .Depend on Figure 6 It can be seen that when the reducing agent is replaced by ascorbic acid from hydroquinone, the morphology of silver nanoparticles changes from nanoplates to nanocubes. Changing the type of reducing agent can regulate the morphology of silver nanoparticles.

[0049] Example 3

[0050] This embodiment provides a method for preparing a patterned gold-silver nanoarray material. The specific steps are similar to those in Example 1, except that the specific steps of step C are as follows:

[0051] A photoresist film was spin-coated on the surface of the gold nanosphere array, baked and cured, and then exposed, developed and fixed using electron beam lithography technology to obtain a patterned gold nanosphere array with grown silver nanostructures; at 50°C, the patterned gold nanosphere array was placed in a 5μmol / L 5-amino-2-mercaptobenzimidazole ligand solution for modification, and then silver nitrate solution and hydroquinone solution were added and mixed thoroughly until the concentration of silver nitrate in the system was 0.3mmol / L and the concentration of reducing agent was 0.3mmol / L, and then placed at 25°C for reaction for 30 minutes, and the photoresist film was removed to finally obtain a patterned gold-silver nanoarray material 3 with a period of 500nm.

[0052] Example 4

[0053] This embodiment provides a method for preparing a patterned gold-silver nanoarray material. The specific steps are similar to those in Example 1, except that the specific steps of step C are as follows:

[0054] A photoresist film was spin-coated on the surface of the gold nanosphere array, baked and cured, and then exposed, developed and fixed using electron beam lithography technology to obtain a patterned gold nanosphere array with grown silver nanostructures; the patterned gold nanosphere array was placed in a 5μmol / L 2-mercaptobenzimidazole carboxylic acid solution for modification, and then silver nitrate solution and ascorbic acid solution were added and mixed thoroughly until the concentration of silver nitrate in the system was 0.3mmol / L and the concentration of reducing agent was 0.3mmol / L, and then placed at 25°C for reaction for 30 minutes, and the photoresist film was removed to finally obtain a patterned gold-silver nanoarray material 4 with a period of 500nm.

[0055] The final products of Examples 3 and 4 were subjected to the following morphology and performance tests:

[0056] (1) Using a scanning electron microscope, the patterned gold-silver nanoarray material 3 prepared in Example 3 and the patterned gold-silver nanoarray material 4 prepared in Example 4 were observed and photographed, as shown in FIG. Figure 7 (a) and (b) are shown. Figure 7 It can be seen that by combining photolithography technology, silver nanoplates and silver nanocubes can be controlled to grow precisely on the gold ball units exposed on the surface, thereby realizing the preparation of patterned gold-silver nanoarrays.

[0057] (2) Using a dark field electron microscope, the patterned gold-silver nanoarray material 3 prepared in Example 3 and the patterned gold-silver nanoarray material 4 prepared in Example 4 were observed and photographed, respectively. Figure 8 (a) and (b) are shown. Figure 8It can be seen that the gold-silver nanoplate and gold-silver nanocube array after growing the silver nanostructure appear azure and cyan respectively under dark field, which has high contrast with the orange of the substrate gold nanosphere array, which is conducive to high-resolution expression of information.

[0058] In summary, it can be seen that the structural units of the gold-silver nanoarray material of the embodiment of the present invention have uniform morphology, uniform size, and are arranged periodically. By changing the type of reducing agent, the morphology of the silver nanoparticles can be regulated. Thereby, the coupling between the gold nanospheres and the silver nanoparticles is regulated to achieve selective absorption and scattering of the incident light, thereby realizing fine control of the color. The obtained graphical gold-silver nanoplate array and gold-silver nanocube array both show clear and bright azure and cyan colors respectively in a dark field environment, and have ultra-high contrast with the orange of the gold nanosphere array, which is conducive to the accurate expression of high-resolution information. In addition, the synthesis method of the material is low in cost, simple in operation process, fast in reaction speed, high in yield, and can be prepared on a large scale, laying the foundation for a universal preparation method of heterogeneous plasma materials.

[0059] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a gold-silver nanoarray material, characterized in that: The steps include: Step A: preparing a monolayer polystyrene microsphere template with an orderly arrangement of polystyrene microspheres having a uniform diameter of 350-2000 nm, and transferring the monolayer polystyrene microsphere template to a silicon wafer surface to obtain a silicon wafer having a monolayer polystyrene microsphere template; Step B, sputtering and depositing a gold film on the surface of the silicon wafer where the monolayer of polystyrene microspheres is located, and annealing at 1000-1100° C. for 2-3 hours to obtain a gold nanosphere array with a diameter of 180-500 nm; Step C, placing the gold nanosphere array in a thiol-containing ligand solution for modification, then adding a silver nitrate solution and a reducing agent solution, reacting at 15-30° C. for 5-50 minutes, and finally preparing a gold-silver nanosphere array material; Alternatively, a photoresist film is spin-coated on the surface of the gold nanosphere array, baked and cured, and then a pattern is depicted using electron beam lithography. After exposure, development, and fixing, a patterned area of the silver nanostructure is obtained. The gold nanosphere array on the patterned surface not covered by the photoresist is placed in a thiol-containing ligand solution for modification. Then, a silver nitrate solution and a reducing agent solution are added, and the reaction is carried out at 15-30° C. for 5-50 minutes. The photoresist film is removed to obtain a patterned gold-silver nanoarray material. The thiol-containing ligand is one of 5-amino-2-mercaptobenzimidazole and 2-mercaptobenzimidazole carboxylic acid; the reducing agent of the reducing agent solution is one of hydroquinone, ascorbic acid, sodium borohydride, glucose, sodium citrate and sodium hypophosphite.

2. The method for preparing the gold-silver nanoarray material according to claim 1, wherein: In step A, a liquid surface self-assembly method is used to prepare an orderly arranged single-layer polystyrene microsphere on a glass slide to obtain a single-layer polystyrene microsphere template, and then the single-layer polystyrene microsphere template is transferred to the silicon wafer surface by using a liquid surface floating ball scooping method.

3. The method for preparing the gold-silver nanoarray material according to claim 2, wherein: The surfaces of the glass slides and silicon wafers were cleaned with acetone, ethanol, piranha solution and deionized water to remove organic matter on the surface, and then cleaned with a UV-ozone cleaner for 10-30 minutes to make the surface hydrophilic.

4. The method for preparing the gold-silver nanoarray material according to claim 1, wherein: In step B, a fully automatic ion sputtering coating apparatus is used for sputter deposition, the current of the sputter deposition is 10-20 mA, and the sputtering time is 8-3 minutes.

5. The method for preparing the gold-silver nanoarray material according to claim 1, wherein: The concentration of the thiol-containing ligand in step C is 1-100 μmol / L.

6. The method for preparing the gold-silver nanoarray material according to claim 1, wherein: The temperature for modification in step C is 40-80°C.

7. The method for preparing the gold-silver nanoarray material according to claim 1, wherein: The type of the photoresist in step C is one of AR-P617PMMA / MA copolymer, PMMA and negative resist, and the molecular weight of the photoresist is one of 200K, 400K, 600K and 950K.

8. The method for preparing the gold-silver nanoarray material according to claim 1 or 5, characterized in that: In step C, silver nitrate solution and reducing agent solution are added to the system until the concentration of silver nitrate is 0.05-0.6 mmol / L and the concentration of reducing agent is 0.05-0.6 mmol / L.

9. A gold-silver nanoarray material prepared by the preparation method of the gold-silver nanoarray material according to any one of claims 1 to 8.

10. Use of the gold-silver nanoarray material according to claim 9 as an information carrier in the field of information anti-counterfeiting.

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