CN108862443A - Gold nanoparticle/graphite alkene three-dimensional optical-thermal conversion material and application thereof - Google Patents

Abstract

Gold nanoparticle and graphene are prepared into gold nanoparticle/graphite alkene nanocomposite using Chemical assembly method by the present invention, and are prepared into gold nanoparticle/graphite alkene three-dimensional optical and thermal (steam) transition material using orientation freeze-drying.Material of the present invention can efficiently convert light energy into thermal energy, water quickly can be heated into vapor, be finally reached water purification purpose, to realize the multiple functions such as sea water desalination, fractionation, sterilizing, sewage treatment.

Description

Gold nanoparticle/graphene three-dimensional light-to-heat conversion material and its application

technical field

The invention belongs to the technical field of chemistry, and specifically relates to new materials and preparation methods thereof, in particular to the preparation and application of gold nanoparticle/graphene three-dimensional photothermal materials.

Background technique

Gold nanoparticles are one of the most widely used photothermal materials. They exhibit strong spectral absorption in the visible light band. When they interact with incident light waves, surface plasmon resonance will occur, and the electron air mass of the entire nanoparticle will Resonance will occur under the action of the light field, and then a large amount of heat will be generated. However, gold nanoparticles mainly act as "microscopic heat sources" in the liquid phase environment, and cannot achieve a large amount of light energy conversion and storage, so it is difficult to effectively use light energy. In order to give full play to the photothermal effect of gold nanoparticles and improve the utilization rate of the infinite light energy in nature, it is necessary to seek better application methods.

Contents of the invention

The invention provides a method of directional freezing to prepare a three-dimensional gold nanoparticle/graphene material. This preparation method makes the pores of the three-dimensional material have orientation, so that the material has higher light-to-heat conversion efficiency.

In order to solve the above technical problems, the invention provides a gold nanoparticle/graphene three-dimensional material, which is prepared by the following method:

(1) Gold nanoparticles are prepared by chemical reduction method,

(2) Preparation of gold nanoparticles/graphene oxide nanocomposites by chemical self-assembly method, as follows:

S-1. prepare graphene oxide with improved Hummers' method,

S-2. grafting the silane coupling agent with mercapto-SH to the surface of the graphene oxide sheet layer prepared above,

S-3. Add the gold nanoparticles prepared by step (1) again, so that the gold nanoparticles are adsorbed on the graphene oxide surface in a large amount, and obtain the gold nanoparticles/graphene oxide nanometer solution,

(3) Gold nanoparticles/graphene three-dimensional light-to-heat conversion materials

The gold nanoparticle/graphene oxide solution obtained in step (2) is placed in a mold for directional freezing, then freeze-dried, and finally heated and reduced to obtain a macroscopic gold nanoparticle/graphene oxide three-dimensional light-to-heat conversion material.

In a preferred technical solution of the present invention, in step (1), a gold compound is used as a raw material to generate gold nanoparticles through a reduction reaction, and the growth of the gold nanoparticles is controlled so that the size thereof reaches nanoscale.

In a preferred technical solution of the present invention, in step (1), utilize the synthetic seed crystal of sodium citrate method, and based on this seed crystal, mercaptosuccinic acid MSA is reducing agent, further prepares the particle size range 20-150nm of gold nanoparticles.

In a preferred technical solution of the present invention, in step S-2, graphene oxide is reacted with silane coupling agent KH590 at a certain temperature, and mercapto groups (-SH) in KH590 are grafted onto the surface of graphene oxide.

In a preferred technical solution of the present invention, in step S-2, dissolve graphene oxide in distilled water, then add silane coupling agent KH590, react at 55°C-70°C for 3 hours, centrifuge and then wash with distilled water several times , to make a graphene oxide solution.

In a preferred technical solution of the present invention, the directional freezing step can obtain different microstructures and porosity of composite materials.

In a preferred technical solution of the present invention, in step (3), the freeze-dried gold nanoparticle/graphene oxide three-dimensional material is heated to 300° C.-700° C. for 2-3 hours under the protection of nitrogen, and the reduction reaction is carried out .

The present invention prepares gold nanospheres and gold nanoparticles through a chemical reduction method, and the chemical reduction method is currently the most widely used and most mature method for preparing gold nanospheres. The chemical reduction method is to use gold compounds as raw materials, generate gold nanoparticles through chemical reduction reaction, and control the growth of gold nanoparticles to make their size reach nanoscale. By adding different types and proportions of reducing agents in the reaction Gold nanoparticles are available in different sizes.

The present invention regulates and prepares gold nanoparticles with different sizes through a seed crystal method. The use of the seed crystal method can not only adjust the preparation of different size controllable and uniform gold nanoparticles.

The surface of graphene oxide sheets contains a large number of oxygen-containing functional groups, which can easily react with silane coupling agents. Since -SH can easily form strong covalent bonds with gold nanoparticles, gold nanoparticles can be adsorbed on the surface of graphene oxide in large quantities. And this kind of adsorption is different from simple physical adsorption, it is a kind of chemical adsorption with strong binding force. Through this method, gold nanoparticles of various shapes and sizes can be combined with graphene oxide, and the composite ratio of gold nanoparticles and graphene oxide can be adjusted by adjusting the amount of coupling agent.

The bottom of the freeze-dried mold is made of stainless steel plate, surrounded by polytetrafluoroethylene, so that it can be directional frozen, and the three-dimensional material with anisotropic hole direction can be obtained, and the orderly three-dimensional photothermal material can be obtained by making the hole face a fixed direction. In the present invention, composite materials with different microstructures and porosities can be obtained by adjusting the freezing rate and the initial gold nanoparticle/graphene oxide concentration, and realize the regulation and control of the microstructure of the macroscopic gold nanoparticle/graphene oxide composite material. The gold nanoparticle/graphene oxide material can be reduced thermally, and the degree of reduction of graphene oxide in the gold nanoparticle/graphene material can be adjusted by controlling the reaction temperature and reaction time.

The second aspect of the present invention provides a gold nanoparticle/graphene three-dimensional material for light-to-heat conversion devices.

The gold nanoparticle/graphene three-dimensional light-to-heat conversion device of the present invention can efficiently convert light energy into heat energy, can quickly heat water into water vapor, and collect distilled water through a reflux device, and finally achieve the purpose of water purification, thereby realizing the field The purpose of quickly preparing clean distilled water.

The gold nanoparticle/graphene three-dimensional light-to-heat conversion device of the present invention can efficiently convert light energy into heat energy, can quickly heat water into water vapor, and collect distilled water through a reflux device to finally achieve the purpose of water purification. Therefore, the purpose of rapidly preparing clean distilled water in the field is realized.

Compared with existing materials, the photothermal conversion device of gold nanoparticles/graphene three-dimensional material has the following advantages:

(1) Graphene three-dimensional material has the advantages of ultra-light weight, high porosity and multi-scale pore structure compared with other macroscopic materials due to its three-dimensional porous structure, and can load a large amount of gold nanoparticles, which makes gold The nanoparticle/graphene three-dimensional material photothermal converter can effectively solve the problems of nanoparticle agglomeration, uneven dispersion, and the inability to increase the doping amount. Microscopic gold nanoparticles can be constructed into a macroscopic heating device to give full play to its photothermal performance. .

(2) Gold nanoparticles mainly absorb incident light with a wavelength of about 500nm and convert it into heat efficiently; while graphene absorbs heat radiation in the near-infrared band and further converts it into heat; therefore, it is different from relying solely on graphene Compared with materials for photothermal conversion with a structure, gold nanoparticles/graphene three-dimensional material photothermal conversion devices can perform photothermal conversion with a wider light wave frequency band.

(3) Both graphene and gold nanoparticles have light-to-heat conversion ability, and at the same time, when the two are combined, their light-to-heat conversion ability will be further enhanced. Therefore, gold nanoparticles/graphene three-dimensional material photothermal conversion devices are compared with The photothermal efficiency of graphene three-dimensional photothermal material will increase by 5%-20%.

(4) This patent adopts the method of directional freezing to prepare gold nanoparticles/graphene three-dimensional material. This preparation method makes the pores of the material have orientation. This structure can not only effectively enhance the light absorption rate of the material, but also can Provide an effective channel for steam to escape, and can quickly export the water vapor generated by heating, so that the light-to-heat (steam) conversion efficiency of the material is higher.

Detailed ways

The above solution will be further described below in conjunction with specific embodiments. It should be understood that these examples are used to illustrate the present invention and not to limit the scope of the present invention. The implementation conditions used in the examples can be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not indicated are usually the conditions in routine experiments.

Embodiment 1 Preparation of gold nanoparticles/graphene three-dimensional material

(1) Preparation of gold nanoparticles of different sizes

Synthetic seed crystals by sodium citrate method: In the preparation process, first add a certain amount of chloroauric acid into a 250ml three-necked bottle, heat it under reflux to 99°C, and then add lemon to the chloroauric acid solution in high-speed stirring Sodium acid solution, the solution will turn from gray to blue and finally wine red, which proves that the gold nanoparticles have been successfully prepared. After continuing to heat and stir for 30 minutes, stop the reaction. (Note: All containers for the reaction were soaked in a mixed solution of concentrated sulfuric acid and potassium dichromate for 30 minutes, washed with distilled water repeatedly after soaking, and finally dried in a vacuum oven for use)

Using mercaptosuccinic acid (MSA) as a reducing agent to prepare gold nanoparticles with a particle size range of 20-150nm. First to the round bottom flask of 100ml, add 0.8ml 5 * 10 ³ M chloroauric acid and various seed crystal solutions (the consumption of seed crystal is the crystal seed of 0.5-5ml concentration 0.1mg/ml), the particle diameter of seed crystal It is 13.1±2nm, the average long-short axis ratio is 1.30, and then diluted to 50ml with distilled water. Then 0.24ml of MSA (0.01M) solution was added and stirred vigorously for 20min. Typically, gold sols prepared by this method are stable for several months. Occasionally sedimentation occurs for large-sized gold nanoparticles, but the sediment can be easily redispersed by shaking the bottle gently.

(2) Preparation of gold nanoparticles/graphene oxide nanocomposites by chemical self-assembly method

Prepare graphene oxide with improved Hummers ' method, concrete method is as follows:

Weigh 1g of sodium nitrate and 50ml of concentrated sulfuric acid and place them in a 2000ml three-neck flask. After the sodium nitrate is dissolved, put the reaction vessel in an ice bath and stir slowly for 1h, then add 1g of raw graphite. Divide 6g of potassium permanganate into the container several times, and gradually add it to the container for about 1 hour, while controlling the temperature of the entire reaction system below 10°C. Afterwards, it was removed from the ice bath, transferred to a 35°C water bath, and stirred slowly for 2 hours. Then slowly add 100ml of distilled water and 30ml of hydrogen peroxide. When the temperature of the reaction system rises to 98±2°C, stir slowly at this temperature for 30min, and the reaction solution gradually turns bright yellow. Repeatedly wash with distilled water for 10 times until the pH of the solution is 7, then centrifuge the solution at a low speed, discard the precipitate, keep the bright yellow graphene oxide solution, and dry it for later use.

Take 0.1g of graphene oxide and dissolve it in 100g of distilled water, then add 0.5g of coupling agent KH590, heat up to 60°C and stir for 4h. After the reaction was finished, the reactant was centrifuged at 5000rpm, and washed repeatedly with distilled water 4 times to remove the coupling agent that did not react completely. After drying, it was dissolved in distilled water again to make a graphene oxide solution, and the graphene oxide solution ( 10ml, 2mg/ml) and the gold nanoparticle solution (1ml, 0.1mg/ml) were mixed, stirred and reacted at room temperature for 30min.

(3) Preparation of gold nanoparticles/graphene three-dimensional materials

Place the previously obtained gold nanoparticle/graphene oxide solution in a specific mold for directional freezing. The bottom of the mold is surrounded by polytetrafluoroethylene, which can achieve the effect of directional freezing, and then the macroscopic gold nanoparticle can be obtained by freeze-drying. Particle/graphene oxide composites. In the freeze-drying step, by adjusting the cooling rate (2°C/min-10°C/min) and the initial concentration of gold nanoparticles/graphene oxide (0.5mg/ml-5mg/ml), composites of different microstructures and porosities can be obtained. Materials, to realize the regulation and control of the microstructure of macroscopic gold nanoparticles/graphene oxide composites. Finally, the gold nanoparticle/graphene oxide material was thermally reduced at a temperature range of 700° C. for 2 hours under the protection of nitrogen to obtain the gold nanoparticle/graphene three-dimensional material.

Example 2 purposes

The three-dimensional gold nanoparticle/graphene material can be used as a light-to-heat (steam) conversion material to realize seawater desalination; the gold nanoparticle/graphene material light-to-heat conversion device of the present invention can efficiently convert light energy into heat energy, and can quickly Seawater is heated into water vapor, and the distilled water is collected through the reflux device to obtain pure water without salt, thereby realizing seawater desalination.

The specific embodiments described above are only preferred implementations of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements or replacements can be made without departing from the principles of the present invention. These improvements Or replacement should also be regarded as the protection scope of the present invention.

Claims (9)

1. gold nanoparticle/graphite alkene three-dimensional optical-thermal conversion material, is prepared by the following method：

(1) gold nanoparticle is prepared in chemical reduction method,

(2) Chemical self-assembly method prepares gold nanoparticle/stannic oxide/graphene nano composite material

S-1. graphene oxide is prepared with improved Hummers ' method,

S-2., silane coupling agent with sulfydryl-SH is grafted to the surface of the graphene oxide layer of aforementioned preparation,

S-3. the gold nanoparticle that step (1) is prepared is added, so that gold nanoparticle is largely adsorbed on graphene oxide Surface obtains gold nanoparticle/stannic oxide/graphene nano solution,

(3) gold nanoparticle/graphite alkene three-dimensional optical-thermal conversion material

Gold nanoparticle/graphene oxide solution that step (2) obtains is placed in mold and orients freezing, it is then dry by freezing It is dry, finally macroscopical gold nanoparticle/graphite alkene three-dimensional optical-thermal conversion material is obtained by heating reduction.

2. according to benefit require 1 described in three-dimensional optical-thermal conversion material, which is characterized in that in step (1), using gold compound make For raw material, gold nanoparticle is generated by reduction reaction, and controls the growth of gold nanoparticle, its size is made to reach nanoscale.

3. according to benefit require 1 described in three-dimensional optical-thermal conversion material, which is characterized in that in step (1), closed using Citrate Buffer At crystal seed, and based on this crystal seed, dimercaptosuccinic acid MSA is reducing agent, further prepares the gold of particle size range 20-150nm Nanoparticle.

4. according to benefit require 1 described in three-dimensional optical-thermal conversion material, which is characterized in that in step S-2, by graphene oxide and silicon Alkane coupling agent KH590 reacts at a certain temperature, and the sulfydryl (- SH) in KH590 is grafted to surface of graphene oxide.

5. according to benefit require 1 described in three-dimensional optical-thermal conversion material, which is characterized in that in step S-2, graphene oxide is dissolved in Distilled water adds silane coupling agent KH590, reacts 3 hours at 55 DEG C -70 DEG C, after centrifugation again wash with distilled water for several times, It is dissolved in distilled water and modified graphene oxide solution is made.

6. according to benefit require 1 described in three-dimensional optical-thermal conversion material, which is characterized in that in step (3), freeze-drying step pass through It is available to adjust 2 DEG C -10 DEG C/min of rate of temperature fall, adjusting starting gold nanoparticle/graphene oxide concentration 0.5-5mg/ml The composite material of diverse microcosmic structure and porosity.

7. according to benefit require 1 described in three-dimensional optical-thermal conversion material, which is characterized in that in step (3), by the gold after freeze-drying Nanoparticle/graphene oxide three-dimensional material under nitrogen protection, is heated to 300 DEG C -700 DEG C, 2-3 hours, restore anti- It answers.

8. turning such as the described in any item gold nanoparticle/graphite alkene three-dimensional optical-thermal conversion materials of claim 1-7 for optical and thermal Parallel operation part.

9. purposes according to claim 8, which is characterized in that the gold nanoparticle/graphite alkene three-dimensional photothermal conversion material Material is for being heated into vapor for water, to reach water purification purpose.