CN106735300B - A kind of synthetic method of ultra-thin silver nanoparticle plate - Google Patents

Abstract

The present invention is a method for synthesizing ultra-thin silver nanoplates, the method comprising: preparing a seed solution with highly consistent seed crystal types by adding a large amount of excessive hydrogen peroxide and a strong reducing agent to a mixed solution of silver nitrate and a surfactant ;Using the seed solution, by controlling the amount of reducing agent and silver nitrate in the reaction process, the first kind of silver nanoplate with controllable shape and size and monodisperse is obtained; through multiple rounds of continuous growth, a random "gap" is obtained and "hot spots" of the second silver nanoplate; through the introduction of halogen ion/hydrogen peroxide etching defects, multiple rounds of continuous growth to obtain the third silver nanoplate with smooth edges, ultra-high aspect ratio, ultra-large and ultra-thin; and through Wrap the above three nanometer plates with unique structures to obtain an ultra-thin silver nanometer plate with a core-shell structure. The invention creatively proposes a preparation method of a nano-plate structure with random "gap" and "hot spot", and solves the problem of poor stability of the silver nano-plate material.

Description

A kind of synthetic method of ultrathin silver nano plate

technical field

The invention relates to the fields of nano-photonics, plasmonics, infrared optics, nano-materials, printed electronics and thin-film devices, in particular to the synthesis and size and shape control methods of ultra-thin silver nano-plates.

Background technique

Silver nanoplate is a special two-dimensional nanomaterial with unique physical and chemical properties. Especially in optics, it has surface plasmon (SPs) effect. When illuminated, the freely vibrating electrons on the surface of the silver nanoplate interact with the incident light to form a resonance, generating localized electromagnetic waves transmitted along the surface. Its properties are closely related to the size of the material.

Small-sized silver nanoplates with a width of several nanometers to tens of nanometers have a localized surface plasmon resonance (LSPR) effect in the visible light band, which can localize the light field around the particle, causing a large increase in local light intensity. . When the size and shape are monodisperse, the resonance absorption peak of the silver nanoplate solution is a single peak, and the peak red shifts with the increase of the size of the nanoplate, resulting in yellow, orange, plum red, purple and blue in the macroscopic sample. And so on a range of different colours. Importantly, the better the monodispersity of the sample, the narrower the FWHM of the resonance absorption peak. On this basis, high-yield small-sized nanoplates can be assembled to form macroscopic thin-film devices. By adjusting the size of the nanoplates, the precise control of the local light field distribution can be realized. In addition to thin-film devices, small-sized silver nanoplates are also widely used in the field of printed electronics to make conductive inks. Studies have shown that for wires of the same size, the resistance of samples composed of silver nanoplates is 4 orders of magnitude lower than that of samples composed of silver nanospheres, which can effectively reduce the resistance of wires. This is because the smaller the size of the metal particle, the more active its atoms are, and the more suitable it is to be used as a conductive ink. However, the silver nanoplate is a two-dimensional anisotropic nanomaterial, and the size in the thickness direction is only a few nanometers, which is much smaller than that of other materials. Shaped nanoparticles. Therefore, silver nanoplates are more likely to form a welding effect with each other to form a bulk material, so the conductivity is significantly higher than that of wires formed by other topographical nanoparticles. And with the increase in the yield of nanoplates, the thickness of nanoplates is thinner, and the morphology of nanoparticles in the ink is uniform, the resistance of printed wires and electronic devices will be further reduced, and the performance will be significantly improved. In summary, the preparation of high-yield, small-sized ultrathin monodisperse silver nanoplates is a research focus in the field of metal nanomaterials and device technology, which can solve the bottleneck problems in the above-mentioned various application fields.

The existing synthesis methods of small-sized silver nanoplates include: photocatalytic reduction method, electrochemical method, ultrasonic method, etc. These methods have long cycles and low yields, and need to be purified to increase the yield. In contrast, the seed crystal growth method separates the generation of the seed crystal from the growth process, controls the reaction conditions according to the requirements of the reaction kinetics in different periods, and can obtain silver nanoplate samples with controllable morphology and size. However, most of the samples prepared by the existing seed crystal method have a high proportion of spherical particles in the final product, and it is impossible to realize monodisperse silver nanoplates. The main bottleneck is that the seed crystals generated at the initial stage of the reaction cannot be fully screened, and the types of seed crystals generated are various, including single crystal seeds and twin crystal seeds, etc. Different types of seed crystals have different particle shapes after continuous growth. , thus directly affecting the increase in yield. Therefore, it is urgent to introduce a more efficient screening mechanism to achieve a high degree of uniformity of seed crystal types. At the same time, the uniformity of the seed crystal will also enhance the controllability of the continuous growth work, increase the concentration of the solution, and obtain silver nanoplates with high yield, high concentration, good crystallinity, and adjustable size.

The surface plasmon resonance (SPR) peak of large-sized nanoplates with a size ranging from hundreds of nanometers to tens of microns can be red-shifted to the mid-to-far infrared, or even to the terahertz band. new application. Therefore, the development of large-size silver nanoplates can fill in the gaps in the available surface plasmon metal nanoplate materials in these wavelength bands. At the same time, large-size silver nanoplates with sizes ranging from hundreds of nanometers to tens of microns are an important subwavelength optical waveguide transmission medium. Since the silver nanoplate has the surface plasmon effect, it can localize the light in the sub-wavelength space, and the formed mode spot is much smaller than the traditional dielectric waveguide, which breaks through the optical diffraction limit and greatly improves the integration of photonic devices. It is the key raw material to realize the next generation ultra-large-scale integrated photonic chip system. The large-scale silver nanomaterial with single crystal structure is itself a high-quality two-dimensional waveguide, which can transmit sub-wavelength information in two-dimensional plane. At the same time, if a special sub-wavelength structure is introduced on the large-size silver nanoplate to form a "hot spot", the sub-wavelength information can also be scattered into space, and the interaction between light and matter can be further strengthened, which will provide great benefits for people. In the case of breaking through the diffraction limit, it provides a new technical method to explore the physical laws of the interaction between light and matter at the mesoscopic scale. Therefore, large-scale silver nanoplates with smooth surfaces and large-scale silver nanoplates with modified surfaces that generate hot spots have important application prospects in the field of nanotechnology.

At present, this large-area and large-size silver nano-film is mainly prepared by traditional coating technology, and then processed into a certain shape through photolithography, etching and other processes. This method is complicated in process and high in cost, and the silver nano film produced is amorphous, the scattering effect is obvious when electrons and photons are transmitted in it, the loss is large, and the performance of the prepared device is low, which cannot meet the actual application requirements. Therefore, researchers propose to use chemically synthesized single crystal silver nanoplates with a size of several microns or more to replace silver nanofilms prepared by thin film deposition technology as raw materials for the preparation of metal waveguide devices. However, the silver nanoplates synthesized by existing chemical methods generally have a thickness of more than 100 nanometers, and thinner large-sized silver nanoplates cannot be prepared by chemical methods, nor can they meet the requirements of existing devices. Theoretical research shows that only when the thickness of the silver nanoplate is reduced to about 20 nanometers, its transmission loss can be significantly reduced, which meets the requirements of practical nanowaveguide devices. Therefore, in order to solve the loss problem of plasmonic waveguide devices and improve device performance, it is urgent to invent a chemical synthesis method that can prepare large-sized, ultra-thin silver nanoplates.

Contents of the invention

Technical problem: The purpose of the present invention is to overcome the deficiencies of the prior art, and propose a method for the synthesis of ultra-thin silver nanoplates, by introducing a competitive mechanism of strong reducing agent/strong oxidizing agent, to achieve a high degree of uniformity of seed crystal types Chemical screening, and strictly control the size and shape through continuous growth, to achieve 100% yield of small-size silver nanoplates, large-size silver nanoplates with "gap" and "hot spots", ultra-thin, ultra-large aspect ratio ( 1000:1) large-size silver nanoplates and various monodisperse silver nanoplates with core-shell structure. The above products have broad application prospects in the fields of printed electronics, thin film devices and nano waveguides.

Technical scheme: the synthetic method of ultra-thin silver nanoplate of the present invention comprises the following steps:

Step 1: Seed growth and screening

Mix silver nitrate and surfactant, stir for 1-3 minutes, and configure mixed solution a, in which the concentration of silver ions is 0.1-100mmol/L; add excess hydrogen peroxide solution to mixed solution a, stir well, wherein hydrogen peroxide is The concentration in the reaction system is 0.5-1000mmol/L, which is more than 5 times the concentration of silver nitrate; after stirring evenly, add an excess of strong reducing agent; at this time, the silver in the solution undergoes repeated and multiple rounds of growth-etching process , accompanied by a series of changes in the color of the solution: transparent, black, light yellow, black, yellow, and black, and finally obtain a twin crystal seed solution with a highly consistent seed type;

Step 2: Preparation of size-controllable monodisperse silver nanoplates

Take the seed solution obtained in step 1, add 10-1000 times of deionized water to dilute, and add reducing agent and surfactant to it to obtain mixed solution b; add silver nitrate solution to mixed solution b for silver nanometer The growth of the plate, wherein the concentration of silver ions in the reaction system is 0.01-100mmol/L; with the increase of the concentration of silver nitrate in the reaction system, the silver nano plate grows gradually, and the mixed solution goes through: yellow, orange, plum red, purple , blue and other series of color changes, and finally generate the first silver nanoplate solution with 100% yield, and the size is precisely adjustable from 10 to 2000 nanometers;

Step 3: Preparation of multiple rounds of continuous growth of silver nanoplates with random "gap" and "hot spots"

Take a small amount of the first silver nanoplate solution obtained in step 2, add deionized water to dilute to a silver concentration of 0.001-100mmol/L; add a small amount of hydrogen peroxide solution to it, stir fully for 3-5 minutes, and perform pre-etching. Strictly control the concentration of hydrogen peroxide in the system to 0.001-100mmol/L, so that the edge of the nanoplate becomes rough and does not break or decompose; after pre-etching, add surfactant and reducing agent to it in sequence, and stir evenly to obtain a mixed solution c; Add silver nitrate solution to the mixed solution c, silver nitrate will generate hydrogen ions when it is reduced, control the concentration of silver ions in the reaction system for each round to be 0.01-100mmol/L to etch rough edges, this etching process Compete with the repair process of the reduced hydrogen atoms to ensure that the edges will not break or decompose while cracks are formed; after fully reacting, add deionized water to dilute to a silver concentration of 0.001-100mmol/L; repeat the above steps 5-6 After several rounds, the color of the solution gradually turns white, and small silver-white particles that can be distinguished by the naked eye appear suspended in the solution, forming the second silver nanoplate solution with many random "gap" and "hot spots" on the edge cracks. When the number of rounds increases When it reaches more than 8 rounds, the size of the nanoplate reaches 3-10 microns, and increases with the number of rounds, and the size remains dynamically stable. By continuing to increase the number of rounds, the output of the second silver nanoplate can be increased;

Step 4: Preparation of ultra-high aspect ratio, ultra-large and ultra-thin silver nanoplates with smooth edges

Get a small amount of the first silver nanoplate solution obtained by step 2, add deionized water to dilute to a silver element concentration of 0.01-100mmol/L; add hydrogen peroxide solution and alkali metal halides to it, and accurately control the concentration of hydrogen peroxide in the system. 0.001-100mmol/L, the concentration of alkali metal halide is 0.001-100mmol/L, and the morphology of the nanoplates is screened in real time during the whole reaction process, so that the rough edges of the nanoplates are quickly decomposed, and only the nanoplates with good crystal orientation are retained. The plate is used for continuous growth; add surfactant and reducing agent to it, and stir for 1-3 minutes to obtain mixed solution d; add silver nitrate solution to mixed solution d, and the concentration of silver ions in the reaction system is 0.01-100mmol /L; after fully reacting, add 10-100 times of deionized water to dilute; repeat the above steps within 2-3 rounds, the growth limit of silver nanoplates can be broken through, and the diameter is about 20 microns, and the thickness is less than 20 nanometers. The third nanoplate solution with a ratio of 1000:1, ultra-high aspect ratio, ultra-large and ultra-thin, with smooth edges;

Step 5: Preparation of core-shell silver nanoplates

Using the silver nanoplate solution obtained in the preparation process of step 2 or step 3 or step 4 as a raw material to prepare a core-shell nanoplate heterostructure, the specific method is as follows:

Dissolve TEOS in ethanol to form a precursor solution with a volume fraction of 0.1%-10%, which is referred to as solution A; take an appropriate amount of the silver nanoplate solution prepared in step 2 or step 3 or step 4 Centrifuge, dilute, and add hydrogen peroxide solution with a mass fraction of 10%-30% to configure solution B; mix solutions A and B according to the ratio of 1: (0.01-10), and keep stirring for more than 5 hours; remove unreacted by centrifugation The excess drug, to obtain uniform, monodisperse core-shell structure of ultra-thin silver nanoplates.

The surfactant includes: polyvinylpyrrolidone PVP, trisodium citrate, mercaptan, polymethacrylic acid, benzoic acid or sodium lactate; the concentration of the surfactant in the reaction system is 0.01-1000mmol/L, and the nitric acid in the reaction system The molar ratio of silver to surfactant is 1:(0.1-10).

The strong reducing agent includes: ascorbic acid AA, formaldehyde, hydrazine hydrate or sodium borohydride; the concentration of the strong reducing agent in the reaction system is 0.5-1000mmol/L, which is more than 5 times the concentration of silver nitrate.

The reducing agent includes: ascorbic acid, formaldehyde, hydrazine hydrate or polyhydric alcohol; the concentration of the reducing agent in the reaction system is 0.01-100mmol/L.

The surfactant includes: polyvinylpyrrolidone, trisodium citrate, mercaptan, polymethacrylic acid, sodium gluconate or sodium dodecyl sulfate SDS; the concentration of the surfactant in the reaction system is 0.01-100mmol /L.

The surfactant includes: polymethacrylic acid, sodium gluconate, trisodium citrate, mercaptan or polyvinylpyrrolidone; the concentration of the surfactant in the reaction system is 0.001-100mmol/L.

The reducing agent includes: ascorbic acid, formaldehyde, hydrazine hydrate or polyhydric alcohol; the concentration of the reducing agent in the reaction system is 0.001-100mmol/L.

The alkali metal halides are: sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide or potassium iodide; wherein, the concentration of the alkali metal halides in the reaction system is 0.001-100 mmol/L.

The surfactant includes: polymethacrylic acid, sodium gluconate, trisodium citrate, mercaptan or polyvinylpyrrolidone; the concentration of the surfactant in the reaction system is 0.001-100mmol/L.

The reducing agent includes: ascorbic acid, formaldehyde, hydrazine hydrate or polyhydric alcohol; the concentration of the reducing agent in the reaction system is 0.001-100mmol/L.

In step four of the method of the present invention, the hydrogen peroxide solution and the alkali metal halide provide an oxygen ion/halide ion etchant with a super-strong oxidation etching effect, and the nanoplate morphology in the entire reaction process is screened in real time, so that The nanoplates with rough edges decompose rapidly, and only the nanoplates with good crystal orientation remain for continuous growth. However, it is necessary to precisely control the concentration of hydrogen peroxide in the system to be 0.001-100mmol/L, and the concentration of alkali metal halides to be 0.001-100mmol/L to ensure that the radially good nanoplates are not decomposed. At the same time, since silver nitrate will generate hydrogen ions during reduction, as the number of rounds increases, hydrogen ions will gradually accumulate, and the oxidation and etching effect will become more and more obvious. Therefore, in order to obtain super large and ultra-thin silver nanoplates, it is necessary to minimize the reaction The number of rounds suppresses the accumulation of hydrogen ions.

Beneficial effect: compared with the prior art, the present invention has the following advantages:

1. The present invention proposes a novel seed crystal preparation method, which is significantly advanced in screening seed crystal methods compared with previously reported methods. By introducing an oxidation/reduction competition mechanism between a strong reducing agent and a strong oxidizing agent, the seed crystal type is screened, and the isotropic seed crystal is etched away, thereby realizing the preparation of a highly consistent planar twinning seed crystal, and suppressing the non-nano The production of plate particles is a breakthrough to the existing preparation method of nano plate. Based on the seed crystal preparation method proposed by the present invention, the preparation of monodisperse silver nanoplates (the first silver nanoplates) in a macro-quantity, high-concentration, and 100% yield has been realized under normal temperature and water-based environment.

2. The monodisperse silver nanoplate solution proposed by the present invention has a single absorption peak in the visible light range, and the minimum width at half maximum is only 80 nanometers, which is one-third of the prior art. In the same volume of aqueous solution, the output is 100 times that of the prior art. Moreover, the synthesis method is simple to operate, has a high success rate, is pollution-free, and the sample size can be precisely regulated. The preparation process does not require complicated equipment, and can realize rapid production in large quantities, which is especially suitable for industrialization.

3. The present invention proposes a brand-new preparation method of a silver nanoplate structure (the second nanoplate) with random "gap" and "hot spot" for the first time, which has not been reported before. The minimum size of these randomly distributed "slits" and "hot spots" is only a few nanometers, and the distribution is relatively concentrated, which can easily stimulate the "slit mode", which makes the local electric field intensity enhanced by hundreds or thousands of times. At the same time, this silver nanoplate with a macroscopic size of more than 5 microns has an obvious two-dimensional conduction mode, which can be used for remote sensing Raman detection of heterogeneous excitation/output and high-resolution remote sensing imaging technology.

4. The present invention realizes the preparation of a super-high aspect ratio, large size, ultra-thin, single crystal silver nanoplate (the third nanoplate) for the first time. The size of this ultra-thin silver nanoplate is about 20 microns, the thickness is less than 20 nanometers, and the aspect ratio is about 1000:1, which is 5-10 times that of existing reports. Its surface plasmon resonance (SPR) peak can be red-shifted to the mid-to-far infrared, and even to the terahertz band, filling the gaps in the available surface plasmon nanoplate materials for these bands. High-quality two-dimensional waveguide devices can also be prepared by electron beam etching technology, which can be used in the development of devices in the fields of optical communication and quantum optics.

Description of drawings

1 is a scanning electron microscope (SEM) image of monodisperse silver nanoplates in Example 1.

Figure 2 is a scanning electron microscope image of silver nanoplates with random "slits" and "hot spots" in Example 2, where the inset is a transmission electron microscope (TEM) image of the region at the edge "slits" and "hot spots".

Fig. 3 is a scanning electron microscope image of the ultra-high aspect ratio, ultra-large and ultra-thin silver nanoplate with flat edges in Example 3.

Detailed ways

Below further illustrate the present invention by specific embodiment and comparative example:

Example 1

Step 1: Seed growth and screening

Take 10 mL of deionized water, add 100 μL of silver nitrate solution with a concentration of 0.5 mol/L and 200 μL of polyvinylpyrrolidone solution with a concentration of 3 mol/L, and stir for 3 minutes to form a mixed solution a; 500 μL of hydrogen peroxide solution with a concentration of 1mol/L was stirred thoroughly; after fully stirring evenly, 500 μL of hydrazine hydrate solution with a concentration of 1mol/L was added; at this time, the silver in the solution experienced repeated and multiple rounds of growth-etching processes, accompanied by The color of the solution has undergone a series of changes: transparent, black, light yellow, black, yellow, and black, and finally a twin crystal seed solution with highly consistent seed crystal types is obtained;

Step 2: Preparation of size-controllable monodisperse silver nanoplates

Take 1L of deionized water, add 5mL of the seed crystal solution obtained in step 1, 5mL of polyvinylpyrrolidone solution with a concentration of 1mol/L and 6mL of ascorbic acid solution with a concentration of 1mol/L to obtain mixed solution b; after fully stirring , add 100mL silver nitrate solution with a concentration of 0.1mol/L to the mixed solution b; as the reaction progresses, the silver nanoplates grow gradually, and the mixed solution undergoes a series of color changes: yellow, orange, plum red, purple, blue, etc. , finally generating the first silver nanoplate solution with 100% yield.

The scanning electron microscope picture of the first kind of silver nanoplate that makes is shown in Fig. 1, as can be seen from Fig. 1, the silver nanoplate that embodiment 1 prepares is evenly distributed, has no other appearance, and diameter is about 400 nanometers, and appearance, size are uniform .

Example 2

Step 1: Seed growth and screening

Take 5 mL of deionized water, add 60 μL of silver nitrate solution with a concentration of 1 mol/L and 60 μL of sodium lauryl sulfate solution with a concentration of 2 mol/L, and stir for 1 minute to form a mixed solution a; Add 300 μL of hydrogen peroxide solution with a concentration of 1 mol/L to the solution, and stir thoroughly; after fully stirring, add 500 μL of a sodium borohydride solution with a concentration of 1 mol/L; at this time, the silver in the solution undergoes repeated and multiple rounds of growth-etching processes , accompanied by a series of changes in the color of the solution: transparent, black, light yellow, black, yellow, and black, and finally obtain a twin crystal seed solution with a highly consistent seed type;

Step 2: Preparation of size-controllable monodisperse silver nanoplates

Take 60 mL of deionized water, add 400 μL of the seed crystal solution obtained in step 1, 50 μL of sodium lauryl sulfate solution with a concentration of 1 mol/L and 100 μL of citric acid solution with a concentration of 1 mol/L to obtain a mixed solution b ; After fully stirring, add 1.5mL of silver nitrate solution with a concentration of 0.5mol/L to the mixed solution b; as the reaction proceeds, the silver nanoplates grow up gradually, and the mixed solution goes through: yellow, orange, plum red, purple, blue Wait for a series of color changes to finally generate the first silver nanoplate solution with 100% yield.

Step 3: Preparation of multiple rounds of continuous growth of silver nanoplates with random "gap" and "hot spots"

Take 60 mL of deionized water, add 200 μL of the silver nanoplate solution obtained in step 5 to it; add 50 μL of hydrogen peroxide solution with a concentration of 0.5 mol/L to it, stir thoroughly for 5 minutes, and perform pre-etching; Add 50 μL of sodium lauryl sulfate solution with a concentration of 1 mol/L and 100 μL of citric acid solution with a concentration of 1 mol/L, stir well to obtain a mixed solution c; add 1.5 mL of 0.5 mol/L to the mixed solution c silver nitrate solution; after fully reacting, take 10mL of the solution, add deionized water to dilute to a volume of 60ml; repeat the above steps in step 3 for 8 rounds, the color of the solution gradually turns white, and small silvery white particles that can be distinguished by the naked eye appear suspended in the solution In the second silver nanoplate solution with many random "slits" and "hot spots" formed along the edge cracks.

The scanning electron microscope picture of the second silver nanoplate prepared is shown in Fig. 2. It can be seen from Fig. 2 that the silver nanoplate prepared in Example 2 has many random "slits" and "hot spots" with a diameter of about 7 microns.

Example 3

Step 1: Seed growth and screening

Take 8 mL of deionized water, add 60 μL of silver nitrate solution with a concentration of 1 mol/L and 100 μL of polymethacrylic acid solution with a concentration of 1 mol/L, and stir for 2 minutes to form a mixed solution a; 100 μL hydrogen peroxide solution with a concentration of 2 mol/L was stirred thoroughly; after fully stirring evenly, 100 μL of a citric acid solution with a concentration of 3 mol/L was added; at this time, the silver in the solution experienced repeated and multiple rounds of growth-etching processes, accompanied by The color of the solution has undergone a series of changes: transparent, black, light yellow, black, yellow, and black, and finally a twin crystal seed solution with highly consistent seed crystal types is obtained;

Step 2: Preparation of size-controllable monodisperse silver nanoplates

Take 80 mL of deionized water, add 400 μL of the seed crystal solution obtained in step 1, 50 μL of polymethacrylic acid solution with a concentration of 1 mol/L, and 100 μL of formaldehyde solution with a concentration of 1 mol/L to obtain mixed solution b; stir thoroughly Finally, 2 mL of silver nitrate solution with a concentration of 0.6 mol/L was added to it; as the reaction progressed, the silver nanoplates grew up gradually, and the mixed solution experienced a series of color changes: yellow, orange, plum red, purple, blue, etc., and finally The first silver nanoplate solution was generated in 100% yield.

Step 3: Preparation of ultra-high aspect ratio, ultra-large and ultra-thin silver nanoplates with smooth edges

Take 80 mL of deionized water, add 100 μL of the silver nanoplate solution obtained in step 5, 100 μL of potassium bromide solution with a concentration of 0.01 mol/L, and 500 μL of a hydrogen peroxide solution with a concentration of 0.2 mol/L; 1mol/L polymethacrylic acid solution and 100μL formaldehyde solution with a concentration of 1mol/L, stirred for 3 minutes to obtain a mixed solution d; add 2mL silver nitrate solution with a concentration of 0.6mol/L to the mixed solution d; fully react Finally, take 10mL of the solution, add deionized water to dilute to a volume of 80ml; repeat the above steps in step 3 within 2 rounds, the growth limit of silver nanoplates can be broken through, and the diameter is about 20 microns, and the thickness is less than 20 nanometers. The third nanoplate solution with a flat edge of 1000:1, ultra-high aspect ratio, ultra-large and ultra-thin.

The scanning electron micrograph of the third kind of silver nanoplate that makes is shown in Fig. 3, as can be seen from Fig. 3, the silver nanoplate edge that embodiment 3 prepares is smooth, and size is big, and diameter is about 20 microns, and thickness is below 20 nanometers, and length The diameter ratio is about 1000:1.

In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included in the scope of protection claimed by the present invention.

Claims (8)

1. a kind of synthetic method of ultra-thin silver nanoparticle plate, it is characterised in that the synthetic method includes the following steps：

Step 1：Crystal seed is grown and screening

Silver nitrate and surfactant are mixed, stirs 1-3 minutes, is configured to mixed solution a, wherein silver ion is a concentration of 0.1-100mmol/L；Excessive hydrogen peroxide solution is added into mixed solution a, is sufficiently stirred, wherein hydrogen peroxide is in reaction system In a concentration of 0.5-1000mmol/L, be 5 times of silver nitrate concentration or more；After stirring evenly, excessive strong reductant is added； At this point, growth-etching process that the galactic longitude in solution is gone through repeatedly, taken turns more, along with solution colour after：Transparent, black, yellowish, A series of black, yellow, black variations finally obtain the twin seed-solution of crystal seed type highly consistentization；

Step 2：It is prepared by the controllable monodisperse silver nanoparticle plate of size

The seed-solution that step 1 obtains is taken, 10-1000 times of the deionized water that taken seed-solution volume is added dilutes, and to Reducing agent and surfactant is wherein added, obtains mixed solution b；Silver nitrate solution is added into mixed solution b, is received for silver The growth of rice plate, the wherein a concentration of 0.01-100mmol/L of silver ion in the reaction system；With silver nitrate in reaction system The increase of concentration, silver nanoparticle plate are gradually grown up, mixed solution after：Huang, orange, plum, purple, a series of blue color changes, finally The first silver nanoparticle plate solution of 100% yield is generated, the nano-plates size dimension of synthesis is accurate adjustable at 10-2000 nanometers；

Step 3：Silver nanoparticle plate with random " gap " and " hot spot " is taken turns continuous growth more and is prepared

The first the silver nanoparticle plate solution obtained on a small quantity by step 2, addition deionized water is taken to be diluted to silver-colored elemental concentration and be 0.001-100mmol/L；A small amount of hydrogen peroxide solution is added thereto, is sufficiently stirred 3-5 minutes, carries out pre-etching, it is stringent to control A concentration of 0.001-100mmol/L of hydrogen peroxide in system keeps nano-plates edge roughening while being unlikely to broken or decomposing；In advance Etching terminates that surfactant and reducing agent is added thereto successively again, is uniformly mixing to obtain mixed solution c；To mixed solution c Middle addition silver nitrate solution, silver nitrate can generate hydrogen ion while reduction, and often wheel silver ion is in the reaction system for control A concentration of 0.01-100mmol/L etches the coarse site in edge, the repair process phase of this etching process and the hydrogen atom of reduction Mutually competition ensures to be unlikely to broken while edge forms cracking or decompose；Fully after reaction, deionized water is added and is diluted to silver Elemental concentration is 0.001-100mmol/L；Step 3 above-mentioned steps 5-6 wheels are repeated, solution colour gradually bleaches, and naked eyes occur can The silvery white little particle distinguished is suspended in solution, and forming edge cracking band, there are many second of the silver medals in random " gap " and " hot spot " Nano-plates solution, when take turns number increase to 8 wheels it is above when, the size dimensions of nano-plates reaches 3-10 micron, and with wheel number growth, ruler The yield of second of silver nanoparticle plate can be improved by continuing growing wheel number for very little holding dynamic stability；

Step 4：The preparation of edge smooth superelevation draw ratio, super large and ultra-thin silver nanoparticle plate

The first the silver nanoparticle plate solution obtained on a small quantity by step 2, addition deionized water is taken to be diluted to silver-colored elemental concentration and be 0.01-100mmol/L；Hydrogen peroxide solution and alkali halide are added thereto, accurately controls the concentration of hydrogen peroxide in system For 0.001-100mmol/L, a concentration of 0.001-100mmol/L of alkali halide, to the nanometer in entire reaction process Plate pattern is screened in real time, and the nano-plates for keeping edge coarse are decomposed rapidly, only retains the good nano-plates of crystal orientation for continuous life It is long；Surfactant and reducing agent is added thereto again, stirs 1-3 minutes, obtains mixed solution d；It is added into mixed solution d Silver nitrate solution, a concentration of 0.01-100mmol/L of silver ion in the reaction system；Fully after reaction, it is added 10-100 times Deionized water dilutes；It repeats within step 4 above-mentioned steps 2-3 wheels, the silver nanoparticle plate growth limit can be broken through, obtain diameter 20 Microns, and thickness is less than 20 nanometers, draw ratio is up to 1000：The smooth superelevation draw ratio in 1 edge, super large and ultra-thin Three kinds of nano-plates solution；

Step 5：It is prepared by nucleocapsid silver nanoparticle plate

It is that raw material prepares core-shell nano using the silver nanoparticle plate solution obtained by step 2 or step 3 or step 4 preparation process Plate heterojunction structure, the specific method is as follows：

Ethyl orthosilicate TEOS is dissolved in ethyl alcohol, the precursor solution that volume fraction is 0.1%-10% is configured to, is denoted as molten Liquid A；The silver nanoparticle plate solution centrifugation made from step 2 or step 3 or step 4 in right amount is taken, dilutes and mass fraction is added and is The hydrogen peroxide solution of 10%-30%, is configured to solution B；By 1：The ratio of (0.01-10) mixes solution A, B, persistently stirs 5 Hour or more；By centrifuging the unreacted excessive drug of removal, uniform, monodispersed core-shell structural ultra-thin silver nanoparticle is obtained Plate.

2. the synthetic method of ultra-thin silver nanoparticle plate as described in claim 1, it is characterised in that：The surfactant includes： Polyvinylpyrrolidone PVP, trisodium citrate, mercaptan, polymethylacrylic acid, benzoic acid or sodium lactate；Surfactant is anti- Answer a concentration of 0.01-1000mmol/L in system, the molar ratio of silver nitrate and surfactant is 1 in reaction system:(0.1- 10)。

3. the synthetic method of ultra-thin silver nanoparticle plate as described in claim 1, it is characterised in that：The strong reductant includes： Ascorbic acid AA, formaldehyde, hydrazine hydrate or sodium borohydride；A concentration of 0.5-1000mmol/L of strong reductant in the reaction system, It is 5 times or more of silver nitrate concentration.

4. the synthetic method of ultra-thin silver nanoparticle plate as described in claim 1, it is characterised in that：The reducing agent includes：It is anti- Bad hematic acid, formaldehyde, hydrazine hydrate or polyalcohol；A concentration of 0.01-100mmol/L of reducing agent in the reaction system.

5. the synthetic method of ultra-thin silver nanoparticle plate as described in claim 1, it is characterised in that：The surfactant packet It includes：Polyvinylpyrrolidone, trisodium citrate, mercaptan, polymethylacrylic acid, sodium gluconate or lauryl sodium sulfate SDS； A concentration of 0.01-100mmol/L of surfactant in the reaction system.

6. the synthetic method of ultra-thin silver nanoparticle plate as described in claim 1, it is characterised in that：The surfactant packet It includes：Polymethylacrylic acid, sodium gluconate, trisodium citrate, mercaptan or polyvinylpyrrolidone；Surfactant is in reactant A concentration of 0.001-100mmol/L in system.

7. the synthetic method of ultra-thin silver nanoparticle plate as described in claim 1, it is characterised in that：The reducing agent includes：It is anti- Bad hematic acid, formaldehyde, hydrazine hydrate or polyalcohol；A concentration of 0.001-100mmol/L of reducing agent in the reaction system.

8. the synthetic method of ultra-thin silver nanoparticle plate as described in claim 1, it is characterised in that：The alkali halide is： Sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide or potassium iodide；Wherein, alkali halide in the reaction system dense Degree is 0.001-100mmol/L.