CN113500201A

CN113500201A - Preparation method and device of gold and core-shell nanocrystalline thereof

Info

Publication number: CN113500201A
Application number: CN202110737480.XA
Authority: CN
Inventors: 田新龙; 邓培林; 沈义俊
Original assignee: Hainan Deep Sea New Energy Technology Co ltd; Hainan University
Current assignee: Hainan Deep Sea New Energy Technology Co ltd; Hainan University
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2021-10-15
Anticipated expiration: 2041-06-30
Also published as: CN113500201B

Abstract

The invention discloses a method and device for preparing gold and core-shell nanocrystals, comprising: mixing a reducing agent and a dispersing agent in a certain volume ratio to form a reaction solution; adding a preset mass of chloroauric acid; when the concentration of the chloroauric acid in the reaction solution is the first molar number, zero-dimensional gold nanoparticles are generated; when the concentration of the chloroauric acid in the reaction solution is the second molar When the concentration of the chloroauric acid in the reaction solution is the third number of moles, two-dimensional gold nanosheets are generated. The application of the invention can control the morphology of the generated nanocrystals by changing the concentration of chloroauric acid in the reaction solution, the operation is simple, and the control of the morphology of the nanocrystals is very flexible and easy to repeat.

Description

Preparation method and device of gold and core-shell nanocrystalline thereof

Technical Field

The invention relates to the technical field of precious metal solution chemical synthesis, in particular to a preparation method and a device of gold and core-shell nanocrystalline thereof.

Background

High quality nanocrystals have been of great interest to researchers because of their unique optical, electronic, magnetic, etc. properties. The gold nano has potential application prospect in the fields of energy chemistry, biomedicine, food science and the like due to the unique properties of size effect, surface effect, high potential and the like. Therefore, the preparation of the gold nanocrystals with different sizes and morphologies has important research significance.

The method for synthesizing gold nanocrystals by a solution chemistry method comprises: white phosphorus reduction, sodium borohydride reduction, ultrasonic ethanol reduction, amine reduction, and the like. The reducing agents used in the above-mentioned techniques include sodium borohydride, sodium citrate, oleylamine, ascorbic acid, tert-butylamine-borane complex, polyvinylpyrrolidone, and the like. Long amine-based reducing agents are of great interest due to their long-term stable presence in polar solvents, as opposed to the strong reducing agent sodium borohydride reduction method. Sun et al first synthesized ultrafine, uniform and monodisperse gold nanocrystals (Nano Res,2008,1,229-234.) by injecting chloroauric acid trihydrate, oleylamine, tetralin and tert-butylamine-borane complex systems. Zhang et al first placed oleylamine and chloroauric acid trihydrate in a small bottle and left for 17 hours to obtain different types of gold nanocrystals and gold nanowire derived alloys (nat. chem.,2018,4, 755-. In addition, gold and palladium also have great application value in the field of homogeneous catalysis, and Xiao et al remarkably improve the activation of C-H bond of methane in a molecular sieve through a domain-limited gold and palladium nanocrystal, thereby promoting the improvement of methanol yield (Science,2020,367, 193-) -197). However, although researchers control and synthesize gold nanocrystals with different morphologies through various solution chemical methods to serve corresponding scientific experimental studies, controlling and synthesizing various required gold nano morphologies still has challenges, and there are technical problems of unclear mechanisms and action mechanisms of formation of various morphologies, poor repeatability and the like.

At present, the synthesis method for synthesizing the gold nanocrystals mainly focuses on a seed crystal two-step growth method, namely, the gold nanocrystals with small sizes are synthesized firstly, centrifuged and cleaned, and then the gold nanocrystals are taken as seed crystals, and precursors of chloroauric acid, a reducing agent of sodium borohydride, a protective agent of hexadecyl trimethyl ammonium bromide and the like are continuously fed to continuously grow the nanocrystals with different shapes. However, the two-step crystal growth method cannot flexibly control the morphology of the generated nanocrystals.

Disclosure of Invention

The invention provides a preparation method and a device of gold and core-shell nanocrystals thereof, which are used for overcoming at least one technical problem in the prior art.

According to a first aspect of the embodiments of the present invention, there is provided a method for preparing gold and core-shell nanocrystals thereof, including: mixing a reducing agent and a dispersing agent according to a certain volume ratio to prepare a reaction solution; adding chloroauric acid with preset mass into the reaction liquid; when the concentration of the chloroauric acid in the reaction liquid is a first mole number, generating zero-dimensional gold nanoparticles; when the concentration of the chloroauric acid in the reaction solution is a second mole number, generating one-dimensional ultra-long gold nanowires; and when the concentration of the chloroauric acid in the reaction solution is a third mole number, generating two-dimensional gold nanoplates.

Optionally, after the step of generating zero-dimensional gold nanoparticles, the method further comprises: increasing the reaction pressure to generate the one-dimensional short gold nanorods.

Optionally, after the step of generating one-dimensional ultra-long gold nanowires, the method further includes: and growing the palladium nanocrystal by epitaxy to generate the gold-palladium core-shell structure nanowire.

Optionally, the decomposition agent comprises: 1,2 dichloropropane or hexane, tetralin; the reducing agent comprises: at least one of long chain amine or oleylamine, ascorbic acid, tert-butylamine-borane complex.

Optionally, the reaction solution is prepared for use; the volume ratio of the reducing agent nuclear dispersant in the reaction liquid is 1-4: 0.1-1, the reaction temperature is 0-70 ℃, and the reaction time is 1-24 hours.

According to a second aspect of the embodiments of the present invention, there is provided a device for preparing gold and core-shell nanocrystals thereof, including: the preparation module is used for mixing a reducing agent and a dispersing agent according to a certain volume ratio to prepare a reaction liquid; the adding module is used for adding chloroauric acid with preset mass into the reaction liquid; the first generation module is used for generating zero-dimensional gold nanoparticles when the concentration of the chloroauric acid in the reaction liquid is a first mole number; the second generation module is used for generating the one-dimensional ultra-long gold nanowires when the concentration of the chloroauric acid in the reaction liquid is a second mole number; and the third generation module is used for generating the two-dimensional gold nanosheets when the concentration of the chloroauric acid in the reaction liquid is a third mole number.

Optionally, the apparatus further comprises: and the fourth generation module is used for increasing the reaction pressure and generating the one-dimensional short gold nanorods.

Optionally, the apparatus further comprises: and the fifth generation module is used for generating the Au-Pd core-shell structure nanowire by epitaxially growing the Pd nanocrystal.

The innovation points of the embodiment of the invention comprise:

1. the method and the device for gold and the core-shell nanocrystalline provided by the invention can be used for fixing the gold and the core-shell nanocrystalline by presetting chloroauric acid with different masses, placing the gold and the core-shell nanocrystalline into reaction liquid, changing the concentration of chloroauric acid in the reaction liquid, and further controlling the morphology of the generated nanocrystalline, so that the method and the device are not only simple and convenient to operate, but also very flexible in controlling the morphology of the generated nanocrystalline and easy to repeat. Is one of the innovative points of the embodiment of the invention.

2. The method can synthesize a series of gold nanocrystals with different morphologies by a one-step method, has the characteristics of simple and convenient operation, high yield, easy repeatability, systematicness and the like, and has potential application prospects in the fields of photoelectrocatalysis, homogeneous catalysis and the like. Is one of the innovative points of the embodiment of the invention.

3. The preparation method and the device of the gold-palladium core-shell nanocrystal provided by the invention can be used for constructing novel noble metal nanometer building blocks on the basis of gold nanocrystals with various shapes, and the advantages of noble metals are complemented to achieve the maximum synergistic effect. Is one of the innovative points of the embodiment of the invention.

4. The invention prepares a series of high-quality gold and core-shell nanocrystals thereof, and provides various selectivity in systematicness and target diversity. Is one of the innovative points of the embodiment of the invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1a is a flow chart of the steps of a method for preparing gold and core-shell nanocrystals thereof in accordance with the present invention;

FIG. 1b is a TEM image of 5nm gold nanoparticles prepared in example 1;

FIG. 2 is a TEM image of 17nm gold nanoparticles prepared in example 2;

FIG. 3 is a TEM image of 11nm gold nanorods prepared in example 3;

FIG. 4 is a TEM image of ultrafine gold nanowires prepared in example 4;

FIG. 5 is a TEM image of the ultra-long gold nanowires prepared in example 5;

FIG. 6 is a TEM image of gold nanoplates prepared in example 6;

FIG. 7 is a TEM image of the ultra-long Au-Pd core-shell nanowire prepared in example 7;

FIG. 8 is a schematic structural diagram of a device for preparing gold and core-shell nanocrystals thereof according to the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

It is to be noted that the terms "comprises" and "comprising" and any variations thereof in the embodiments and drawings of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

The embodiment of the invention discloses a preparation method and a device of gold and core-shell nanocrystals thereof. The following are detailed below.

The invention provides a preparation method of gold and a core-shell nanocrystal thereof, which can flexibly prepare gold nanoparticles, gold nanorods, gold nanowires and gold nanoplates by adjusting the concentration of chloroauric acid. Referring to fig. 1a, fig. 1a is a schematic processing flow diagram of a method for preparing gold and core-shell nanocrystals thereof according to the present invention. As shown in fig. 1a, the preparation method of gold and its core-shell nanocrystal comprises the following steps:

step 101, mixing a reducing agent and a dispersing agent according to a certain volume ratio to prepare a reaction solution.

Wherein the dispersant comprises 1,2 dichloropropane or hexane, tetralin; the reducing agent comprises at least one of a long chain amine or oleylamine, ascorbic acid, tert-butylamine-borane complex.

The reaction solution is used as it is, the volume ratio of the reducing agent nuclear dispersant in the reaction solution is 1-4: 0.1-1, the reaction temperature is 0-70 ℃, and the reaction time is 1-24 h.

In one implementation, the dispersant may further include at least one of chloroform, ethanol, deionized water, and acetone.

Step 102, adding chloroauric acid with preset mass into the reaction liquid.

In this step, a predetermined amount of chloroauric acid solid may be added to the reaction solution generated in step 1, and nanocrystals with different morphologies may be generated according to the concentration of molten chloroauric acid in the reaction solution. The nanocrystals with different morphologies specifically include gold nanoparticles, gold nanorods, gold nanowires, and gold nanoplates.

103, generating zero-dimensional gold nanoparticles when the concentration of the chloroauric acid in the reaction solution is a first mole number.

In the step, when the concentration of the chloroauric acid in the reaction solution is a first mole number, zero-dimensional gold nanoparticles are generated, and the size of the zero-dimensional gold nanoparticles is usually 5-20 nm.

The first mole number comprises 0.1-1 mmol; and adding a chloroauric acid solid with a preset mass into the reaction liquid, wherein the concentration of the obtained chloroauric acid is the first mole number.

It should be noted that specific description of the generation of gold nanoparticles can refer to example 1 and example 2.

Alternatively, when the dispersing agent is hexane and the concentration of the chloroauric acid is a first mole number, one-dimensional ultrafine gold nanowires can be generated.

It should be noted that, the specific description of the generation of the one-dimensional ultra-fine gold nanowires can refer to example 4.

In one implementation, after step 104, the reaction pressure is increased to generate one-dimensional short gold nanorods.

It should be noted that, for a specific description of the generation of one-dimensional short gold nanorods, reference may be made to example 3.

And 104, generating the one-dimensional ultra-long gold nanowire when the concentration of the chloroauric acid in the reaction liquid is a second mole number.

In this step, when the concentration of chloroauric acid in the reaction solution is a second mole number, one-dimensional ultra-long gold nanowires are generated, and the length of the generated gold nanowires is usually 1 to 15 μm.

Note that said second number of moles comprises less than 0.07 mmol; and adding a chloroauric acid solid with a preset mass into the reaction liquid, wherein the concentration of the obtained chloroauric acid is the second mole number.

It should be further noted that, for the specific description of the generation of the one-dimensional ultra-long gold nanowires, reference may be made to example 5.

In one implementation, after step 104, the pd nanocrystals are grown epitaxially to produce pd core-shell nanowires.

The palladium can be epitaxially grown on the surface of each gold nanocrystal to form a gold-palladium core-shell structure; the core-shell structure also comprises gold platinum, gold palladium platinum, gold iridium, gold rhodium, gold silver and gold ruthenium.

It should be noted that, the specific description of the generation of the au-pd core-shell nanowire can refer to example 7.

And 105, generating two-dimensional gold nanoplates when the concentration of the chloroauric acid in the reaction solution is a third mole number.

In the step, when the concentration of the chloroauric acid in the reaction solution is a third mole number, two-dimensional gold nanoplatelets are generated, wherein the length-diameter ratio of the gold nanoplatelets is usually 1-5 μm.

The third mole number comprises 0.08-0.09 mmol; and adding a chloroauric acid solid with a preset mass into the reaction solution, wherein the concentration of the obtained chloroauric acid is a third mole number.

It should be noted that, for a specific description of the generation of two-dimensional gold nanoplates, reference may be made to example 6.

Therefore, the method for preparing gold and the core-shell nanocrystalline provided by the invention can be used for fixing the gold and the core-shell nanocrystalline by presetting chloroauric acids with different masses, putting the gold and the core-shell nanocrystalline into reaction liquid, changing the concentration of the chloroauric acid in the reaction liquid, and further controlling the morphology of the generated nanocrystalline. Specifically, when the concentration of chloroauric acid in the reaction solution is 0.1-1 mmol, zero-dimensional gold nanoparticles are generated; when the concentration of the chloroauric acid in the reaction solution is lower than 0.07mmol, generating one-dimensional ultra-long gold nanowires; and when the concentration of the chloroauric acid in the reaction liquid is 0.08-0.09 mmol, generating the two-dimensional gold nanosheets. Not only the operation is simple and convenient, but also the control on the appearance of the generated nanocrystalline is very flexible and easy to repeat.

The specific experimental conditions are as follows:

example 1:

preparing zero-dimensional 5nm gold nanoparticles. Dissolving 0.5-5 mmol of chloroauric acid in 10-50 mL of oleylamine and 10-50 mL of tetralin, cooling to a required temperature, injecting oleylamine/tetralin mixed solution containing tert-butylamine-borane complex, carrying out vortex oscillation at the reaction temperature of 0-60 ℃ for 0.5-2 h, and carrying out multiple centrifugal separation and acetone washing to obtain the ultrafine 5nm gold nanoparticles. FIG. 1b is a TEM image of 5nm gold nanoparticles prepared in example 1, as shown in FIG. 1 b.

Example 2:

preparing zero-dimensional 12nm gold nanoparticles. Dissolving 0.5-2 mmol of chloroauric acid in 1-5 mL of oleylamine and 0.1-1.5 mL of 1, 2-dichloropropane, heating to the required temperature, standing for reaction at 0-70 ℃, reacting for 1-24 h, and performing centrifugal separation and acetone washing for multiple times to obtain the gold nanoparticles with the particle size of 12 nm. As shown in FIG. 2, FIG. 2 is a TEM image of 17nm gold nanoparticles prepared in example 2.

Example 3:

preparing 11nm gold nano short rods. Dissolving 0.1-0.9 mmol of chloroauric acid in 1-5 mL of oleylamine and 0.1-1.5 mL of 1, 2-dichloropropane, heating to the required temperature, increasing the reaction pressure, keeping the reaction temperature at 0-70 ℃, reacting for 1-24 h, and performing centrifugal separation and acetone washing for multiple times to obtain the 11nm gold nanorod. As shown in FIG. 3, FIG. 3 is a TEM image of 11nm gold nanorods prepared in example 3.

Example 4:

preparing one-dimensional superfine gold nanowires. Dissolving 0.1-1 mmol of chloroauric acid in 1-5 mL of oleylamine and 0.1-1.5 mL of hexane, heating to the required temperature, standing for reaction at the reaction temperature of 0-70 ℃ for 1-24 h, and performing centrifugal separation and acetone washing for multiple times to obtain the superfine gold nanowires. As shown in FIG. 4, FIG. 4 is a TEM image of the ultrafine gold nanowires prepared in example 4.

Example 5:

preparing one-dimensional ultra-long gold nanowires. Dissolving 0.001-0.07 mmol of chloroauric acid in 1-5 mL of oleylamine and 0.1-1.5 mL of 1, 2-dichloropropane, heating to the required temperature, standing for reaction at the reaction temperature of 0-70 ℃ for 1-24 h, and performing centrifugal separation and acetone washing for multiple times to obtain the ultra-long gold nanowire. As shown in FIG. 5, FIG. 5 is a TEM image of the ultra-long gold nanowire prepared in example 5.

Example 6:

and preparing the two-dimensional gold nanoplates. Dissolving appropriate 0.08-0.09 mmol of chloroauric acid in 1-5 mL of oleylamine and 0.1-1.5 mL of 1, 2-dichloropropane, heating to the required temperature, standing for reaction at the reaction temperature of 0-70 ℃ for 1-24 h, and performing centrifugal separation and acetone washing for multiple times to obtain the gold nanosheets. As shown in FIG. 6, FIG. 6 is a TEM image of the gold nanoplatelets prepared in example 6.

In one implementation, the precursor may include sodium chloropalladate in addition to the chloroauric acid to generate the ultra-long gold-palladium nanowire. See example 7 for a specific description.

Example 7:

based on the embodiment 5, 1-20 mg of gold nanowires are dispersed in ethanol, 0.01-0.5 mM of ascorbic acid is introduced into a reduced sodium chloropalladate aqueous solution under vortex vibration, and the solution is kept stand for 1-24 hours. And (4) obtaining the ultra-long gold-palladium nanowire through heart separation and acetone washing. As shown in fig. 7, fig. 7 is a TEM image of the ultra-long pd-au core-shell nanowire obtained in example 6.

In summary, the present invention has the following advantages:

(1) the method can synthesize a series of gold nanocrystals with different morphologies only by one-step method, has the characteristics of simple and convenient operation, high yield, easy repeatability, systematicness and the like, and has potential application prospects in the fields of photoelectrocatalysis, homogeneous catalysis and the like.

(2) The invention provides a preparation method of gold-palladium core-shell nanocrystals, which is characterized in that novel noble metal nano building blocks are constructed on the basis of gold nanocrystals with various morphologies, and the advantages of noble metals are complemented to achieve the maximum synergistic effect.

(3) The invention prepares a series of high-quality gold and core-shell nanocrystals thereof, and provides various selectivity in systematicness and target diversity.

The invention also provides a preparation device of gold and the core-shell nanocrystalline thereof, and referring to fig. 8, fig. 8 is a schematic structural diagram of the preparation device of gold and the core-shell nanocrystalline thereof. As shown in fig. 8, the apparatus 80 for preparing gold and core-shell nanocrystals thereof includes:

a configuration module 801, configured to mix a reducing agent and a dispersing agent according to a certain volume ratio to prepare a reaction solution;

an adding module 802, configured to add chloroauric acid of a preset mass to the reaction solution;

a first generating module 803, configured to generate zero-dimensional gold nanoparticles when the concentration of the chloroauric acid in the reaction solution is a first mole number;

a second generating module 804, configured to generate one-dimensional ultra-long gold nanowires when the concentration of the chloroauric acid in the reaction solution is a second mole number;

a third generating module 805, configured to generate two-dimensional gold nanoplates when the concentration of the chloroauric acid in the reaction solution is a third mole number.

Therefore, the gold and core-shell nanocrystal preparation device provided by the invention can be fixed by presetting chloroauric acids with different masses, put into reaction liquid, change the concentration of the chloroauric acid in the reaction liquid, and further control the morphology of the generated nanocrystal. Specifically, when the concentration of chloroauric acid in the reaction solution is 0.1-1 mmol, zero-dimensional gold nanoparticles are generated; when the concentration of the chloroauric acid in the reaction solution is lower than 0.07mmol, generating one-dimensional ultra-long gold nanowires; and when the concentration of the chloroauric acid in the reaction liquid is 0.08-0.09 mmol, generating the two-dimensional gold nanosheets. Not only the operation is simple and convenient, but also the control on the appearance of the generated nanocrystalline is very flexible and easy to repeat.

Those of ordinary skill in the art will understand that: the figures are merely schematic representations of one embodiment, and the blocks or flow diagrams in the figures are not necessarily required to practice the present invention.

Those of ordinary skill in the art will understand that: modules in the devices in the embodiments may be distributed in the devices in the embodiments according to the description of the embodiments, or may be located in one or more devices different from the embodiments with corresponding changes. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of gold and core-shell nanocrystals thereof is characterized by comprising the following steps:

mixing a reducing agent and a dispersing agent according to a certain volume ratio to prepare a reaction solution;

adding chloroauric acid with preset mass into the reaction liquid;

when the concentration of the chloroauric acid in the reaction liquid is a first mole number, generating zero-dimensional gold nanoparticles;

when the concentration of the chloroauric acid in the reaction solution is a second mole number, generating one-dimensional ultra-long gold nanowires;

and when the concentration of the chloroauric acid in the reaction solution is a third mole number, generating two-dimensional gold nanoplates.

2. The method of claim 1, wherein after the step of generating zero-dimensional gold nanoparticles, the method further comprises:

increasing the reaction pressure to generate the one-dimensional short gold nanorods.

3. The method of claim 1, wherein after the step of generating one-dimensional ultralong gold nanowires, the method further comprises:

and growing the palladium nanocrystal by epitaxy to generate the gold-palladium core-shell structure nanowire.

4. The method of claim 1,

the decomposition agent comprises: 1,2 dichloropropane or hexane, tetralin;

the reducing agent comprises: at least one of long chain amine or oleylamine, ascorbic acid, tert-butylamine-borane complex.

5. The method of claim 1,

the reaction solution is prepared for use;

the volume ratio of the reducing agent nuclear dispersant in the reaction liquid is 1-4: 0.1-1, the reaction temperature is 0-70 ℃, and the reaction time is 1-24 hours.

6. A preparation device of gold and core-shell nanocrystalline thereof is characterized by comprising:

the preparation module is used for mixing a reducing agent and a dispersing agent according to a certain volume ratio to prepare a reaction liquid;

the adding module is used for adding chloroauric acid with preset mass into the reaction liquid;

the first generation module is used for generating zero-dimensional gold nanoparticles when the concentration of the chloroauric acid in the reaction liquid is a first mole number;

the second generation module is used for generating the one-dimensional ultra-long gold nanowires when the concentration of the chloroauric acid in the reaction liquid is a second mole number;

and the third generation module is used for generating the two-dimensional gold nanosheets when the concentration of the chloroauric acid in the reaction liquid is a third mole number.

7. The apparatus of claim 6, further comprising:

and the fourth generation module is used for increasing the reaction pressure and generating the one-dimensional short gold nanorods.

8. The apparatus of claim 6, further comprising:

and the fifth generation module is used for generating the Au-Pd core-shell structure nanowire by epitaxially growing the Pd nanocrystal.

9. The apparatus of claim 6,

the decomposition agent comprises: 1,2 dichloropropane or hexane, tetralin;

10. The apparatus of claim 6,

the reaction solution is prepared for use;