CN110479319B - Au/CuSe tangential heterogeneous nano material and preparation method thereof - Google Patents

Abstract

The invention relates to a method for preparing Au/CuSe tangentially heterogeneous nanomaterials, comprising: S1. preparing a nano-gold colloid solution under a hexadecyltrimethylammonium bromide system, wherein the particle size of the gold nanospheres is 18-18 22nm; S2. Preparation of sodium selenide solution, using aqueous phase synthesis method with gold nanospheres as growth substrate, sodium selenide and copper acetate as precursors, ascorbic acid as reducing agent, cetyltrimethylammonium bromide as surface The active agent is to grow two-dimensional copper selenide nanodiscs in the tangential direction of gold nanospheres by vacuum reaction in the presence of hexamethylenetetramine to obtain an aqueous solution of Au/CuSe tangential heterogeneous nanomaterials; S3. Separation, cleaning and The Au/CuSe tangentially heterogeneous nanomaterials were obtained by drying. The invention prepares the Au/CuSe tangential heterogeneous nanomaterial by the all-water phase method, and the obtained heterogeneous nanomaterial has stable morphology and structure, obvious double plasmon coupling effect and excellent photocatalytic hydrogen production performance.

Description

A kind of Au/CuSe tangential heterogeneous nanomaterial and preparation method thereof

technical field

The invention relates to the technical field of preparation of inorganic nanometer materials, in particular to an Au/CuSe tangentially heterogeneous nanometer material and a preparation method thereof.

Background technique

Two-dimensional copper selenide nanodisks have excellent photoelectric conversion properties, large specific surface area, abundant reaction sites, and strong near-infrared plasmon photon absorption, showing great application potential in the field of photocatalysis. However, due to the weak absorption of 2D copper selenide nanomaterials in the visible light band and the fast recombination rate of carriers generated by photoexcitation, their practical photocatalytic performance is greatly limited. Combining metal nanocrystals with plasmonic properties and two-dimensional semiconductor nanomaterials, the synergistic effect of plasmons and excitons can greatly improve the photocatalytic performance of heterostructures. Since the plasmonic optical properties of metal nanocrystals are highly correlated with their morphology and structure, the photocatalytic performance of metal/2D semiconductor heteronanomaterials largely depends on their morphological framework. The traditional methods for preparing metal/2D semiconductor material heterostructures are mainly divided into the following two categories: 1) depositing metal nanocrystals on the surface of the prepared 2D semiconductor material by chemical or physical methods; The direct mixing of metallic nanocrystals and semiconducting 2D materials. The morphology and structure of the heterostructures prepared by these two methods are difficult to control, and the plasmon energy utilization rate is low, so their photocatalytic performance is poor.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides an Au/CuSe tangential heterogeneous nanomaterial with efficient photocatalytic performance and a preparation method thereof.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a preparation method of Au/CuSe tangential heterogeneous nanomaterials, comprising the following steps:

S1. Preparation of nano-gold colloidal solution under cetyltrimethylammonium bromide system, wherein the particle size of gold nanospheres is 18～22nm;

S2. prepare sodium selenide solution, adopt the aqueous phase synthesis method to use described gold nanospheres as growth substrate, use sodium selenide and copper acetate as precursors, use ascorbic acid as reducing agent, use cetyltrimethyl bromide as Ammonia is used as a surfactant, and two-dimensional copper selenide nanodiscs are grown in the tangential direction of gold nanospheres under vacuum in the presence of hexamethylenetetramine to obtain an aqueous solution of Au/CuSe tangentially heterogeneous nanomaterials. The reaction system The concentrations of gold nanospheres, sodium selenide hydride, copper acetate, ascorbic acid, hexamethylenetetramine and hexadecyltrimethylammonium bromide are 25.96-31.76nM, 0.52-0.87mM, 0.48-0.90 respectively. mM, 8.08～15.01mM, 8.08～15.01mM, 19.63～26.56mM, the reaction temperature is 85～95℃, and the reaction time is 7.5～8.5h;

S3. Separating, cleaning and drying the aqueous solution of the Au/CuSe tangentially heterogeneous nanomaterial to obtain the Au/CuSe tangentially heterogeneous nanomaterial.

The copper ions generated by copper acetate are complexed on the surface of gold nanospheres under the action of cetyltrimethylammonium bromide and ascorbic acid, and are combined with sodium selenide to generate CuSe, which is in cetyltrimethyl ammonium bromide and ascorbic acid. Two-dimensional copper selenide nanodisks were grown in the tangential direction of gold nanospheres with the assistance of ammonium bromide, and Au/CuSe tangentially heterogeneous nanomaterials were obtained. The invention utilizes an all-water phase method to prepare the Au/CuSe tangential heterogeneous nanomaterial, the prepared heterogeneous nanomaterial has stable morphology and structure, obvious double plasmon coupling effect, and excellent photocatalytic hydrogen production performance.

Further, the step S1 includes:

S1.1 Mix and react chloroauric acid solution, hexadecyltrimethylammonium bromide solution and sodium borohydride solution to obtain nano-gold seed solution;

S1.2 Mix chloroauric acid solution, ascorbic acid solution, and hexadecyltrimethylammonium bromide solution to obtain a first solution, and add the nano-gold seed solution obtained in step S1.1 into the first solution, The pH is adjusted to 1.3-11.7, and the nano-gold colloid solution is obtained by reaction.

The beneficial effect of adopting the above-mentioned further scheme is that the particle size of the gold nanospheres obtained by this method is relatively uniform and controllable. In the process of seed growth, by controlling the ratio of the seed to each substance in the first solution, the production can be controlled Gold nanospheres of different sizes.

Further, the sodium borohydride solution is a sodium borohydride ice-water mixture.

The beneficial effect of adopting the above-mentioned further scheme is to control the temperature of the reaction to slow down the rate of the reaction, so that the seeds grow slowly, so that the particle size of the gold nanospheres is uniform and controllable.

Further, in the step S1.1, when the volumes of chloroauric acid solution, cetyltrimethylammonium bromide and sodium borohydride solution are respectively 500 μL, 8 mL and 600 μL, the chloroauric acid solution, hexadecane The concentrations of trimethylammonium bromide and sodium borohydride solution are respectively 0.048-0.052M, 0.08-0.12M and 0.009-0.011M, the reaction time is 2-2.5h, and the stirring is carried out at 1000 r/min during the reaction.

Further, in the step S1.2, when the volumes of the nano-gold seed solution, chloroauric acid solution, ascorbic acid solution and cetyltrimethylammonium bromide solution are respectively 30 μL, 6 mL, 3.5 mL and 30 mL, the chlorine The concentrations of gold acid solution, ascorbic acid solution and cetyltrimethylammonium bromide are 4.5-5.5mM, 8-16mM and 0.17-0.23M respectively, the reaction time is 1-2h, after the reaction is completed, the reaction product is 10000rpm Centrifuge for 15 min and redisperse the pellet in deionized water.

The beneficial effect of adopting the above-mentioned further scheme is that gold nanoparticles of 18-22 nm can be obtained under control.

Further, the preparation method of the sodium selenide solution is as follows: dissolving sodium borohydride in water, placing it in a freezer at 20-6～-4°C for 6-10min, adding selenium powder to the above sodium borohydride aqueous solution, and stirring until completely dissolved to obtain the sodium selenide solution, the molar ratio of the sodium borohydride to the selenium powder is (1.9-2.1):1, and the concentration of the sodium selenide is 0.75-0.125M.

Further, the specific steps of the step S3 are as follows: the Au/CuSe tangentially heterogeneous nanomaterial aqueous solution is cooled and centrifuged at 8000-10000 rpm for 5 minutes to obtain a solid product, the solid product is alternately washed with deionized water and ethanol, and placed in a drum. The Au/CuSe tangential heterogeneous nanomaterials are obtained by maintaining at 60-70° C. in an air drying oven for 10-12 hours.

Further, the specific steps of the step S2 are as follows: take 5 mL of the nano-gold colloidal solution prepared in the step S1 with a concentration of about 45-55 nM, add 1 mL of ascorbic acid, 1 mL of hexamethylenetetramine, 1 mL of hexadecyltrimethyl Ammonia bromide, 60 μL of sodium selenide solution and 600 μL of copper acetate solution to obtain a second mixed solution, the second mixed solution was transferred to a reaction vessel for packaging, placed in a vacuum drying box, evacuated, and heated to 85-95 ℃ of reaction for 7.5～8.5h, the concentrations of the ascorbic acid, hexamethylenetetramine solution, cetyltrimethylammonium bromide solution, sodium selenide solution and copper acetate solution are respectively 870～130mM, 70～ 130 mM, 170-230 mM, 75-125 mM and 7-13 mM.

The present invention also provides the Au/CuSe tangential heterogeneous nanomaterial prepared by the above preparation method.

The morphology and structure of the Au/CuSe tangential heterogeneous nanomaterial prepared by the invention is stable, and the photocatalytic hydrogen production performance of the heterostructure is enhanced by the coupling of gold nanospheres and copper selenide double plasmons.

Description of drawings

Fig. 1 is the transmission electron microscope photograph of the Au/CuSe tangential heterogeneous nanomaterial prepared in Example 3 of the present invention;

2 is a transmission electron microscope photograph of a part of the side surface of the Au/CuSe tangential heterogeneous nanomaterial prepared in Example 3 of the present invention;

Figure 3 shows the rate of photocatalytic hydrogen production under illumination by using the Au/CuSe tangentially heterogeneous nanomaterials prepared in Example 3, pure copper selenide, and the mixture of Au and CuSe as catalysts, respectively.

Detailed ways

The principles and features of the present invention will be described below with reference to the accompanying drawings and specific embodiments. The examples are only used to explain the present invention, but not to limit the scope of the present invention.

All the following solutions are aqueous solutions unless otherwise specified.

Example 1

(1) Preparation of nano-gold seed solution

8mL of 0.1M hexadecyltrimethylammonium bromide solution, 0.5mL of 0.05M concentration of chloroauric acid solution and 0.6mL of 0.01M concentration of sodium borohydride ice-water mixture were added to the test tube for reaction at room temperature for 2h , during the reaction, stir with a magnet, and set the magnetic stirrer to 1000 rpm to obtain a nano-gold seed solution.

(2) Preparation of nano-gold colloidal solution

Take 30mL of 0.2M hexadecyltrimethylammonium bromide, 6mL of 5mM chloroauric acid solution and 3.5mL of 0.01M ascorbic acid solution to mix to obtain the first solution, and 40μL of step (1) obtained The nano-gold seed solution was added to the first solution, and then 1 mL of sodium hydroxide with a concentration of 1 M was added to adjust the pH value to between 11.3 and 11.7. After completion, the product was centrifuged at 10,000 rpm for 15 min, and re-dispersed into an equal volume of deionized water to obtain a gold nanoparticle colloidal solution with a concentration of 45-55nM, wherein the average particle size of the gold nanoparticles was 20nm.

By controlling the ratio of the seed to each substance in the first solution, gold nanoparticles of different sizes can be controlled and produced, and the gold nanoparticles colloidal solutions with average particle diameters of 18 nm and 22 nm are prepared by the same method.

The preparation of embodiment 2 sodium selenide hydride

Weigh 75.66 mg of sodium borohydride and dissolve it in 10 mL of deionized water, freeze it at -4°C for 8 min, add 78.96 mg of selenium powder to the frozen sodium borohydride solution, and continue to stir until it is completely dissolved to obtain a concentration of 0.1 M. Sodium selenide solution, by adjusting the concentration of sodium borohydride and selenium powder, prepare sodium selenide solutions with concentrations of 75 mM and 125 mM, respectively.

Example 3 Preparation of Au/CuSe Tangential Heterogeneous Nanomaterials

Take 5mL of nano-gold colloidal solution with a concentration of 50nM and an average particle size of 20nm prepared in Example 1, add 1mL of ascorbic acid solution with a concentration of 0.1M, 1mL of hexamethyltetramine solution with a concentration of 0.1M and 1mL with a concentration of 0.2 M cetyltrimethylammonium bromide solution, then add 60 μL of 0.1 M sodium selenide solution and 600 μL of 10 mM copper acetate solution to obtain a second mixed solution, transfer the second mixed solution to a test tube encapsulated, placed in a vacuum drying box, evacuated and heated to 90 °C and kept for 8 h to obtain an aqueous solution of Au/CuSe tangential heterogeneous nanomaterials, cooled to room temperature, and centrifuged at 8000 rpm for 5 min to obtain a solid product. The product was washed alternately with deionized water and ethanol, dried at 65 °C in a blast drying oven and kept for 12 h to obtain Au/CuSe tangential heterogeneous nanomaterials.

FIG. 1 is a transmission electron microscope photograph of the Au/CuSe tangentially heterogeneous nanomaterial prepared in this example. The figure shows that the average diameter of the gold nanospheres is about 20 nm, and the diameter of the CuSe nanodisks is about 45 nm.

FIG. 2 is a transmission electron microscope photograph of a part of the side of the Au/CuSe tangentially heterogeneous nanomaterial prepared in the present embodiment, and part of the side in the figure shows that the CuSe nanodisk is tangent to the Au nanosphere, and the thickness of the CuSe nanodisk is about 5.5 nm.

Example 4

Take 5mL of the nano-gold colloid solution with a concentration of 55nM and an average particle size of 18nm prepared in Example 1, add 1mL of ascorbic acid solution with a concentration of 0.13M, 1mL of hexamethyltetramine solution with a concentration of 0.13M and 1mL with a concentration of 0.23M. M hexadecyltrimethylammonium bromide solution, then add 60 μL of 0.125M sodium selenide solution and 600 μL of 13mM copper acetate solution to obtain a second mixed solution, transfer the second mixed solution to a test tube Vacuum packaged, placed in a vacuum drying box and then heated to 95°C and kept for 8.5h to obtain an aqueous solution of Au/CuSe tangential heterogeneous nanomaterials, cooled to room temperature, and centrifuged at 10,000rpm for 5min to obtain a solid product. The product was washed alternately with deionized water and ethanol, dried at 60 °C in a blast drying oven and kept for 12 h to obtain Au/CuSe tangential heterogeneous nanomaterials.

Example 5

Take 5mL of the nano-gold colloidal solution with a concentration of 45nM and an average particle size of 22nm prepared in Example 1, add 1mL of ascorbic acid solution with a concentration of 0.07M, 1mL of hexamethyltetramine solution with a concentration of 0.07M and 1mL with a concentration of 0.17M. M hexadecyltrimethylammonium bromide solution, then add 60 μL of 0.075M sodium selenide solution and 600 μL of 7mM copper acetate solution to obtain a second mixed solution, transfer the second mixed solution to a test tube Vacuum packaged, placed in a vacuum drying box, heated to 85°C and kept for 7.5h to obtain an aqueous solution of Au/CuSe tangential heterogeneous nanomaterials, cooled to room temperature, and centrifuged at 8000rpm for 5min to obtain a solid product. The product was washed alternately with deionized water and ethanol, dried at 70 °C in a blast drying oven and kept for 10 h to obtain Au/CuSe tangential heterogeneous nanomaterials.

Test example

The Au/CuSe tangential heterogeneous nanomaterials prepared in Example 3, pure copper selenide (other steps of the preparation method are the same as those in Example 2, except that 5 mL of Au nanospheres are not added), and the mixture of Au and CuSe were used as The photocatalytic hydrogen production rate was compared under the light condition (wavelength greater than 420nm).

When the mixture of Au and CuSe is used as the catalyst, Au and CuSe are mixed in a mass ratio of 1:16.5.

The specific experimental process is as follows: take 50 mg of catalyst, add 50 mL of a mixed solution of sodium sulfide and sodium sulfite, wherein the concentration of sodium sulfide is 0.35M, the concentration of sodium sulfite is 0.25M, the above solution is placed in a quartz reactor, and the The quartz reactor was installed on a commercial photocatalytic evaluation system with a 300-watt xenon lamp and a UV-cut filter (wavelength greater than 420 nm). The temperature of the whole reaction system is maintained by circulating cooling water, and the temperature of circulating cooling water is set to 2 degrees. The volume of hydrogen was monitored in real time by gas chromatography, and the volume of hydrogen produced was recorded every hour.

The results are shown in Fig. 3. The hydrogen production rate of the Au/CuSe tangential heterogeneous nanomaterials catalyzed the reaction for 7 hours is 3.77 mmol/g, which is higher than that of pure CuSe (0.67 mmol/g) and the direct mixing of Au and CuSe (0.82 mmol/g). millimoles per gram).

The hydrogen production rates of the Au/CuSe tangential heterogeneous nanomaterials prepared in Example 4 and Example 5 were 3.65 and 3.7 mmol/g, respectively, which were higher than those of CuSe (0.67 mmol/g) and the direct reaction rate of 7 hours. Au and CuSe were mixed (0.82 mmol per gram).

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection of the present invention. within the range.

Claims (8)

1. A preparation method of Au/CuSe tangential heterogeneous nano material is characterized by comprising the following steps:

s1, preparing a nano gold colloidal solution in a hexadecyl trimethyl ammonium bromide system, wherein the particle size of gold nanospheres is 18-22 nm; the step S1 includes:

s1.1, mixing a chloroauric acid solution, a hexadecyl trimethyl ammonium bromide solution and a sodium borohydride solution for reaction to obtain a nano-gold seed solution;

s1.2, mixing a chloroauric acid solution, an ascorbic acid solution and a hexadecyl trimethyl ammonium bromide solution to obtain a first solution, adding the nano gold seed solution obtained in the step S1.1 into the first solution, adjusting the pH value to 11.3-11.7, and reacting to obtain a nano gold colloidal solution;

s2, preparing a sodium hydroselenide solution, taking the gold nanospheres as a growth substrate, taking sodium hydroselenide and copper acetate as precursors, taking ascorbic acid as a reducing agent, taking hexadecyl trimethyl ammonium bromide as a surfactant, and reacting in vacuum in the presence of hexamethylenetetramine to grow a two-dimensional copper selenide nanodisk in the tangential direction of the gold nanospheres to obtain an Au/CuSe tangential heterogeneous nanomaterial aqueous solution, wherein the concentrations of the gold nanospheres, the sodium hydroselenide, the copper acetate, the ascorbic acid, the hexamethylenetetramine and the hexadecyl trimethyl ammonium bromide in a reaction system are respectively 25.96-31.76 nM, 0.52-0.87 mM, 0.48-0.90 mM, 8.08-15.01 mM and 19.63-26.56 mM, the reaction temperature is 85-95 ℃, and the reaction time is 7.5-8.5 h;

s3, centrifuging the Au/CuSe tangential heterogeneous nano material aqueous solution to obtain a solid product, and cleaning and drying the solid product to obtain the Au/CuSe tangential heterogeneous nano material.

2. The method for preparing Au/CuSe tangential heterogeneous nano-material according to claim 1, wherein the sodium borohydride solution is a sodium borohydride ice-water mixture.

3. The method for preparing Au/CuSe tangential heterogeneous nano-material according to claim 2, wherein when the volumes of the chloroauric acid solution, the cetyltrimethylammonium bromide and the sodium borohydride solution in the step S1.1 are 500 μ L, 8mL and 600 μ L respectively, the concentrations of the chloroauric acid solution, the cetyltrimethylammonium bromide and the sodium borohydride solution are 0.048-0.052M, 0.17-0.23M and 0.009-0.011M respectively, the reaction time is 2-2.5 h, and the stirring is performed at 1000 rpm during the reaction process.

4. The method for preparing Au/CuSe tangential heterogeneous nano-material according to claim 3, wherein in the step S1.2, when the volumes of the nanogold seed solution, the chloroauric acid solution, the ascorbic acid solution and the cetyltrimethyl ammonium bromide solution are 30 μ L, 6mL, 3.5mL and 30mL respectively, the concentrations of the chloroauric acid solution, the ascorbic acid solution and the cetyltrimethyl ammonium bromide are 4.5-5.5 mM, 8-16 mM and 0.17-0.23M respectively, the reaction time is 1-2 h, after the reaction is completed, the reaction product is centrifuged at 10000rpm for 15min, and the precipitate is re-dispersed into deionized water.

5. The method for preparing Au/CuSe tangential heterogeneous nano-material according to claim 1, wherein the method for preparing the sodium hydroselenide solution comprises the following steps: dissolving sodium borohydride in water, freezing at the temperature of-6 to-4 ℃ for 6 to 10min, adding selenium powder into the sodium borohydride aqueous solution, and stirring until the selenium powder is completely dissolved to obtain the sodium selenide solution, wherein the molar ratio of the sodium borohydride to the selenium powder is 1.9 to 2.1: 1, the concentration of the sodium hydroselenide is 0.75-0.125M.

6. The method for preparing the Au/CuSe tangential heterogeneous nano material as claimed in any one of claims 1 to 5, wherein the specific step of the step S3 is to cool the aqueous solution of the Au/CuSe tangential heterogeneous nano material to room temperature, then centrifuge the solution at 8000 to 10000rpm for 5 minutes to obtain a solid product, alternately clean the solid product with deionized water and ethanol, and place the solid product in a forced air drying oven at 60 to 70 ℃ for 10 to 12 hours to obtain the Au/CuSe tangential heterogeneous nano material.

7. The method for preparing Au/CuSe tangential heterogeneous nano-material according to any one of claims 1 to 5, wherein the step S2 comprises the following specific steps: taking 5mL of the nano gold colloidal solution prepared in the step S1, adjusting the concentration to 45-55 nM, adding 1mL of ascorbic acid, 1mL of hexamethylenetetramine, 1mL of hexadecyl trimethyl ammonium bromide, 60 muL of sodium selenide hydride solution and 600 muL of copper acetate solution to obtain a second mixed solution, transferring the second mixed solution to a reaction container for packaging, placing the second mixed solution in a vacuum drying box for vacuumizing, heating to 85-95 ℃ for reaction for 7.5-8.5 h, wherein the concentrations of the ascorbic acid, the hexamethylenetetramine solution, the hexadecyl trimethyl ammonium bromide solution, the sodium selenide hydride solution and the copper acetate solution are 870-130 mM, 70-130 mM, 170-230 mM, 75-125 mM and 7-13 mM respectively.

8. An Au/CuSe tangential heterogeneous nano material, which is characterized by being prepared by the preparation method of any one of claims 1 to 7.

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