CN113415821A

CN113415821A - Hollow ZnxCd1-xPreparation method and application of S solid solution nanosphere

Info

Publication number: CN113415821A
Application number: CN202110612545.8A
Authority: CN
Inventors: 潘军; 鲁利利; 刘洪沁; 谭鹏飞; 翟欢欢
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2021-06-02
Filing date: 2021-06-02
Publication date: 2021-09-21
Anticipated expiration: 2041-06-02
Also published as: CN113415821B

Abstract

The invention discloses a hollow Zn_xCd_1‑xThe preparation method of S solid solution nanospheres and the application thereof are characterized in that silicon dioxide nanospheres are used as templates, added Zn and Cd ions are complexed with ammonia water and hydrolyzed under the alkalescent condition to generate hydroxyl complex, the hydroxyl complex reacts with thiourea, and Zn is firstly formed through continuous reaction etching_xCd_1‑xS shell layer grows on the surface of the silicon dioxide ball, then strong alkali is added to remove the silicon dioxide template, and hollow Zn is obtained_xCd_1‑xAnd (4) an S nanosphere. The method realizes hollow Zn by a continuous reaction etching method_xCd_1‑xOne-step synthesis of S solid solution nanosphereAnd the loss of Zn element under the condition of multi-step alkaline etching is avoided. Zn prepared by the method_xCd_1‑xS has high activity of hydrolyzing water to produce hydrogen, and the maximum amount of S can be 2.52 mmoleg under the irradiation of visible light^‑1h^‑1And (4) hydrogen production efficiency. In addition, the preparation process has the advantages of simple synthesis, mild reaction conditions, rich and cheap raw materials and the like.

Description

Hollow ZnxCd1-xPreparation method and application of S solid solution nanosphere

Technical Field

The invention belongs to the technical field of nano material preparation, and particularly relates to hollow Zn_xCd_1-xA preparation method and application of S solid solution nanospheres.

Background

As an important photocatalytic hydrogen production material, transition metal sulfides are widely reported due to their characteristics of direct band gap, narrow forbidden band width, large exciton binding energy, and the like. Transition metal sulfides are generally lamellar structures, which are bonded by van der waals interactions between layers, and which give transition metal sulfides unique physical and chemical properties: such as high active specific surface, adjustable band gap, increased exciton binding energy, and the like.

Zn_xCd_1-xS is a CdS based solid solution.

The main preparation methods at present comprise hydrothermal method, solvent thermal method and the like. Usually hydrothermal and solvothermal synthesis of Zn_xCd_1-xThe S solid solution needs to be completed at high temperature and high pressure. Zn synthesized by the method_xCd_1-xThe S shape growth is difficult to control, the synthesis condition is harsh, the cost is high, and the yield is low, so that the industrial batch production is difficult.

Disclosure of Invention

Aiming at the defects of the prior art, the first purpose of the invention is to provide the hollow Zn which has mild synthesis conditions, simple and controllable process and is suitable for industrial batch production_xCd_1-xA preparation method of S solid solution nanospheres.

The second purpose of the invention is to provide the hollow Zn prepared by the preparation method and having excellent natural light absorptivity and photocatalytic hydrogen production efficiency and uniform components_xCd_1-xS solid solution nanospheres.

The third purpose of the invention is to provide a hollow Zn_xCd_1-xApplication of S solid solution nanospheres.

In order to achieve the above purpose, the invention provides the following technical scheme:

the invention relates to a hollow Zn_xCd_1-xThe preparation method of the S solid solution nanosphere comprises the following steps: dispersing silicon dioxide nanospheres in water to obtain a dispersion liquid, adding a sodium citrate solution, a cadmium source, a zinc source, ammonia water and a sulfur source into the dispersion liquid, mixing to obtain a mixed liquid, reacting the mixed liquid at 60-90 ℃ for 150-240 min, adding sodium hydroxide to obtain a reaction liquid, carrying out etching reaction, cooling, washing and drying the obtained product to obtain the hollow Zn_xCd_1-xAnd (4) an S nanosphere.

The preparation method of the invention takes the silicon dioxide nanospheres as the template, sodium citrate as the surface modifier, added Zn and Cd ions are complexed with ammonia water under the alkalescent condition to generate hydroxyl complex, the hydroxyl complex reacts with thiourea, anions are replaced by sulfur to generate sulfide, and Zn is finally formed_xCd_1-xS shell layer grows on the surface of the silicon dioxide nanosphere, then sodium hydroxide is directly added in the final stage of growth to etch the silicon dioxide template, namely Zn grows on the silicon dioxide nanosphere through liquid phase continuous reaction etching_xCd_1-xS shell layer and removing the silicon dioxide template to obtain hollow Zn_xCd_1-xAnd (4) an S nanosphere. The method realizes hollow Zn by a continuous reaction etching method_xCd_1-xAnd the S solid solution nanospheres are synthesized in one step, so that the loss of Zn element under the alkaline etching condition is avoided.

In the invention, the time for adding the sodium hydroxide for etching is very important, the sodium hydroxide needs to be added in the later period of the reaction, and if the sodium hydroxide is added in the early period, Zn is added due to the early period_xCd_1-xThe S shell layer is thin and fragile in the etching process, and if sodium hydroxide is used for separately etching step by step after the reaction is finished, the loss of the Zn element can be caused. In addition, in the present invention, it is also necessary to effectively control the reaction temperature, and if the reaction temperature is low, Zn is caused_xCd_1-xThe S shell layer grows slowly and has poor crystallinity, if the reaction temperature is high, the local growth of the shell layer is too fast, and the appearance is difficult to maintain in the etching process.

Preferably, the concentration of the silicon dioxide nanospheres in the dispersion liquid is 0.35-0.55 mg/L.

Preferably, the concentration of the sodium citrate in the mixed solution is 2.5-9 mmol/L.

Preferably, the cadmium source is selected from one of a cadmium nitrate solution, a cadmium acetate solution and a cadmium chloride solution, and is preferably a cadmium nitrate solution.

Preferably, the concentration of cadmium ions in the mixed solution is 0.001-0.005 mol/L, preferably 0.002-0.004 mol/L.

In the invention, Zn with proper thickness can be smoothly grown by controlling the proportion relationship between the silicon dioxide nanospheres and the raw materials_xCd_1-xAnd (4) an S shell layer.

Preferably, the zinc source is selected from one of a zinc nitrate solution, a zinc acetate solution and a zinc chloride solution, and is preferably a zinc nitrate solution.

Preferably, in the mixed solution, the molar ratio of zinc ions to cadmium ions is 0-8: 1 to 7. Preferably 3-7: 3 to 7.

Preferably, the sulfur source is selected from one of thiourea, sodium sulfite, thioacetamide and sodium sulfide, and is preferably thiourea.

Preferably, in the mixed solution, in terms of molar ratio, (zinc ion + cadmium ion): elemental sulfur is 1: 1.5 to 5.

Preferably, NH is dissolved in the ammonia water₃The mass fraction of the ammonia water is 20-25 wt%, and the volume ratio of the ammonia water to the water in the dispersion liquid is 1: 80-120, preferably 1: 100 to 110.

Preferably, the concentration of the sodium hydroxide in the reaction liquid is 0.5-2 mol/L.

In the actual operation process, firstly, sodium hydroxide is dissolved in water to obtain a sodium hydroxide solution with the concentration of 10mol/L, and then the sodium hydroxide solution is added into the mixed solution.

The inventor finds that the reaction effect is better when the sodium hydroxide is prepared into a solution and then added into the dispersion liquid, and the sodium hydroxide is dissolved and generates heat if the sodium hydroxide is directly added, so that the local concentration of the sodium hydroxide is too high to influence the product.

Preferably, the etching reaction time is 10-60min, and the product obtained after the etching reaction is cooled to room temperature through an ice bath.

In the actual operation process, after the etching reaction is finished, the product is cooled to the temperature of the etching reaction through ice bathWashing the Zn powder for multiple times by using ultrapure water and absolute ethyl alcohol at room temperature, centrifugally collecting precipitates, and drying to obtain hollow Zn_xCd_1-xAnd (4) an S nanosphere.

The invention also provides the hollow Zn prepared by the preparation method_xCd_1-xS solid solution nanospheres.

The invention also provides the hollow Zn prepared by the preparation method_xCd_1-xApplication of S solid solution nanosphere to preparation of hollow Zn_xCd_1-xThe S solid solution nanosphere is used for hydrogen production by photolysis of water. The catalytic hydrogen production efficiency can reach 2.52 mmoleg at most under the visible light^-1h^-1。

Compared with the prior art, the invention has the advantages that:

1. the method prepares hollow Zn_xCd_1-xThe S is thin in thickness and large in specific surface area, and is beneficial to improving the natural light absorption rate and the photocatalytic hydrogen production efficiency of the material.

2.Zn_xCd_1-xS is a material that is not acid-resistant nor alkali-resistant. The invention adopts a synthesis method of continuous reactive etching, and well removes the silicon dioxide template on the premise of avoiding the loss of zinc element in the etching process, thereby obtaining the hollow Zn_xCd_1-xAnd (4) an S nanosphere.

3. The synthesis method is simple, the reaction condition is mild, and the subsequent treatment is not needed. Can realize industrialized mass production.

Drawings

Fig. 1 is an SEM image of a monodisperse silica nanosphere template used in the present invention. Monodisperse SiO used in the invention₂The SEM of the template is shown in FIG. 1, which exists as spheres with diameters below 500 nm.

FIG. 2 shows a hollow Zn obtained in example 2 of the present invention_0.3Cd_0.7SEM image of S solid solution nanospheres. From FIG. 2 it can be seen that Zn_0.3Cd_0.7S generally forms a spherical structure. Wherein the sphere is a hollow structure as seen from a broken sphere.

FIG. 3 shows a hollow Zn obtained in example 2 of the present invention_0.3Cd_0.7TEM images of S solid solution nanospheres. From the TEM image of FIG. 3It can be seen that the results are consistent with SEM, Zn_0.3Cd_0.7S presents a distinct hollow spherical structure.

FIG. 4 shows the hollow Zn obtained in examples 1 to 4 of the present invention_xCd_1-xXRD patterns of S solid solution nanospheres.

FIG. 5 shows the hollow Zn obtained in examples 1 to 4 of the present invention_xCd_1-xAnd (3) a UV-vis absorption spectrum of the S solid solution nanosphere.

FIG. 6 shows the hollow Zn obtained in examples 1 to 4 of the present invention_xCd_1-xAnd (3) a photocatalytic hydrogen production performance diagram of the S solid solution nanosphere.

FIG. 7 shows a hollow Zn film obtained in comparative example 1 of the present invention_xCd_1-xSEM image of S solid solution nanospheres.

FIG. 8 is an SEM image of comparative example 2 of the present invention.

FIG. 9 is an SEM image of comparative example 3 of the present invention.

Fig. 10 is an EDS plot of example 2 (top), comparative example 4 (middle) and comparative example 3 (bottom).

Detailed Description

The synthesis of the present invention is further described below by way of specific implementation. In particular, the embodiments described herein are only a part of the present invention, and not all embodiments, and all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any inventive work are within the scope of the present invention.

The invention is further described with reference to the following figures and specific examples.

Example 1

Ultrasonically dispersing 55mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution; 5mL of 0.1mol/L cadmium nitrate solution; 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. After the mixture was stirred at 80 ℃ and reacted for 170min, 10mL of 10mol/L sodium hydroxide solution was added and etched for 20 min. And after etching is finished, rapidly cooling the product to room temperature through ice bath, washing the product for a plurality of times by using ultrapure water and absolute ethyl alcohol, centrifugally collecting precipitates, and drying in an oven to obtain the hollow CdS nanosphere-material 1.

Example 2

Ultrasonically dispersing 55mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution; 1.5mL of 0.1mol/L zinc nitrate and 3.5mL of 0.1mol/L cadmium nitrate solution; 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. After the mixture was stirred at 80 ℃ and reacted for 170min, 10mL of 10mol/L sodium hydroxide solution was added and etched for 20 min. After etching is finished, the product is rapidly cooled to room temperature through ice bath, ultrapure water and absolute ethyl alcohol are used for washing the product for a plurality of times, precipitates are centrifugally collected, and the precipitate is placed in an oven to be dried to obtain hollow Zn_0.3Cd_0.7S nanospheres-material 2.

FIG. 3 shows a hollow Zn obtained in example 2 of the present invention_0.3Cd_0.7TEM images of S solid solution nanospheres. As can be seen from the TEM image of FIG. 3, the results are in agreement with SEM, Zn_0.3Cd_0.7S presents a distinct hollow spherical structure.

FIG. 10 is an EDS chart of comparative example 3 (lower) of example 2 (upper) and comparative example 4 (middle), with specific element contents as shown in Table 1:

table 1 EDS element content of material 2 obtained in example 2

Element	Weight％	Atomic％	Net Int.	Error％	Kratio	Z	A	F
									S K	22.08	46.39	1844.40	2.75	0.2311	1.1518	0.8918	1.0189
CdL	61.90	37.10	1807.30	1.98	0.5181	0.8478	0.9877	0.9996
									ZnK	16.02	16.51	111.00	6.03	0.1698	1.0189	0.9894	1.0510

Example 3

Ultrasonically dispersing 55mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution, 2.5mL of 0.1mol/L zinc nitrate and cadmium nitrate solution and 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. After the mixture was stirred at 80 ℃ and reacted for 170min, 10mL of 10mol/L sodium hydroxide solution was added and etched for 20 min. After etching is finished, the product is rapidly cooled to room temperature through ice bath, ultrapure water and absolute ethyl alcohol are used for washing the product for a plurality of times, precipitates are centrifugally collected, and the precipitate is placed in an oven to be dried to obtain hollow Zn_0.5Cd_0.5S nanospheres-material 3.

Example 4

Ultrasonically dispersing 55mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution; 3.5mL of 0.1mol/L zinc nitrate and 1.5mL of 0.1mol/L cadmium nitrate solution; 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. After the mixture was stirred at 80 ℃ and reacted for 170min, 10mL of 10mol/L sodium hydroxide solution was added and etched for 20 min. After etching is finished, the product is rapidly cooled to room temperature through ice bath, ultrapure water and absolute ethyl alcohol are used for washing the product for a plurality of times, precipitates are centrifugally collected, and the precipitate is placed in an oven to be dried to obtain hollow Zn_0.7Cd_0.3S nanospheres-material 4.

Testing the photocatalytic hydrogen production performance of the materials 1 to 4:

10mg each of the materials 1 to 4 obtained in examples 1 to 4 was dispersed in a quartz reactor containing 100mL of ultrapure water, and 1.313g of sodium sulfite and 8.4g of sodium sulfide as sacrificial agents were added, and after 30 minutes of sonication, the reactor was put into a vacuum system to evacuate dissolved gases in the solution. The reactor is maintained at a constant temperature of 5 ℃ and is continuously stirred, a 300W xenon lamp is adopted to test the hydrogen production rate of the sample through photolysis, and a filter is usedThe waveplate filters incident light with a wavelength of less than 420 nm. The hydrogen production was measured every 1 hour. The production of hydrogen was measured by a gas chromatograph equipped with a thermal conductivity detector. As a result, as shown in FIG. 6, it can be seen that excellent hydrogen generation performance was exhibited except that the hydrogen generation performance of the material 1 was slightly inferior, of which the most preferable was the material 4, H₂The yield can reach 2.52 mmoleg at most^-1h^-1。

Comparative example 1

Ultrasonically dispersing 50mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution; 8mL of mixed solution of 0.07mol/L zinc nitrate and 0.03mol/L cadmium nitrate; 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. After the mixture was stirred at 80 ℃ and reacted for 170min, 10mL of 10mol/L sodium hydroxide solution was added and etched for 20 min. After etching is finished, the product is rapidly cooled to room temperature through ice bath, ultrapure water and absolute ethyl alcohol are used for washing the product for a plurality of times, precipitates are centrifugally collected, and the precipitate is placed in an oven to be dried to obtain hollow Zn_0.7Cd_0.3S nanosphere-comparative 1. FIG. 7 is an SEM image of comparative sample 1, and as a result, it was found that too much addition of the Zn/Cd source resulted in partial Zn_xCd_1-xS nucleate and grow separately.

Comparative example 2

Ultrasonically dispersing 50mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution; 2mL of a mixed solution of 0.07mol/L zinc nitrate and 0.03mol/L cadmium nitrate; 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. Stirring the mixed solution at 80 ℃ and reacting for 170min, rapidly cooling the product to room temperature by ice bath, washing the product for a plurality of times by using ultrapure water and absolute ethyl alcohol, centrifuging, collecting precipitate, and drying in an oven to obtain the hollow Zn_0.7Cd_0.3S nanosphere-control 2. FIG. 8 is an SEM image of comparative 2 where too little Zn/Cd source addition results in a too thin shell.

Comparative example 3

Ultrasonically dispersing 55mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution; 5mL of 0.1mol/L zinc nitrate; 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. After the mixture was stirred at 80 ℃ and reacted for 170min, 10mL of 10mol/L sodium hydroxide solution was added and etched for 20 min. And after etching, rapidly cooling the product to room temperature through ice bath, washing the product for several times by using ultrapure water and absolute ethyl alcohol, centrifugally collecting precipitates, and drying in an oven to obtain the hollow ZnO nanosphere-comparison sample 3. Fig. 9 is an SEM image of comparative example 3, and fig. 10 is an EDS image of comparative example 3 (upper) and comparative example 4 (middle) showing that the product is converted into zinc oxide due to an excessive Zn content ratio.

Comparative example 4

Ultrasonically dispersing 55mg of monodisperse silicon dioxide nanospheres into 105mL of ultrapure water, and sequentially adding 5mL of 0.12mol/L sodium citrate solution; 3.5mL of 0.1mol/L zinc nitrate and 1.5mL of 0.1mol/L cadmium nitrate solution; 1mL of 25 wt% ammonia water; 0.5mol/L thiourea was added in an amount of 4mL and mixed well. Stirring the mixed solution at 80 ℃ and reacting for 170min, rapidly cooling the product to room temperature by ice bath, washing the product with ultrapure water and absolute ethyl alcohol for a plurality of times, centrifugally collecting precipitate, etching the product in 1mol/L NaOH for 20min, washing the etched product with ultrapure water and absolute ethyl alcohol for a plurality of times, centrifugally collecting precipitate, placing the product in an oven and drying to obtain the hollow Zn_0.7Cd_0.3S nanosphere-control 4. FIG. 10 is an EDS chart of comparative example 3 (lower) of example 2 (upper) and comparative example 4 (middle), with specific element contents as shown in Table 2:

table 2 EDS elemental content of control 4

Element	Weight％	Atomic％	Net Int.	Error％	Kratio	Z	A	F
									S K	20.00	46.48	2423.99	3.33	0.2077	1.1613	0.8720	1.0258
CdL	79.00	52.38	3506.54	2.36	0.6794	0.8688	0.9904	0.9995
									ZnK	1.00	1.14	16.85	42.88	0.0108	1.0272	0.9794	1.0686

It can be seen that the reacted product is separately etched to prepare Zn_0.7Cd_0.3S, EDS showed no Zn element.

Claims

1. Hollow Zn_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: the method comprises the following steps: dispersing silicon dioxide nanospheres in water to obtain a dispersion liquid, adding a sodium citrate solution, a cadmium source, a zinc source, ammonia water and a sulfur source into the dispersion liquid, mixing to obtain a mixed liquid, reacting the mixed liquid at 60-90 ℃ for 150-240 min, adding sodium hydroxide to obtain a reaction liquid, carrying out etching reaction, cooling, washing and drying the obtained product to obtain the hollow Zn_xCd_1-xAnd (4) an S nanosphere.

2. A hollow Zn according to claim 1_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: in the dispersion liquid, the concentration of the silicon dioxide nanospheres is 0.35-0.55 mg/L, and the concentration of the sodium citrate in the mixed liquid is 2.5-9 mmol/L.

3. A hollow Zn according to claim 1_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: the cadmium source is selected from one of a cadmium nitrate solution, a cadmium acetate solution and a cadmium chloride solution, and the concentration of cadmium ions in the mixed solution is 0.001-0.005 mol/L.

4. A hollow Zn according to claim 1_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: the zinc source is selected from zinc nitrate solution, zinc acetate solution and zinc chloride solutionIn the mixed solution, the molar ratio of zinc ions to cadmium ions is 0-8: 1 to 7.

5. A hollow Zn according to claim 1_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: the sulfur source is selected from one of thiourea, sodium sulfite, thioacetamide and sodium sulfide, and in the mixed solution, the molar ratio of (zinc ion + cadmium ion): elemental sulfur is 1: 1.5 to 5.

6. A hollow Zn according to claim 1_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: dissolving NH in the ammonia water₃The mass fraction of the ammonia water is 20-25 wt%, and the volume ratio of the ammonia water to the water in the dispersion liquid is 1: 80-120 parts.

7. A hollow Zn according to claim 1_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: in the reaction solution, the concentration of sodium hydroxide is 0.5-2 mol/L.

8. A hollow Zn according to claim 1_xCd_1-xThe preparation method of the S solid solution nanosphere is characterized by comprising the following steps: the etching reaction time is 10-60min, and the product obtained after the etching reaction is cooled to room temperature through ice bath.

9. Hollow Zn produced by the production method according to any one of claims 1 to 8_xCd_1-xS solid solution nanospheres.

10. Hollow Zn produced by the production method according to any one of claims 1 to 8_xCd_1-xThe application of the S solid solution nanosphere is characterized in that: hollow Zn is formed_xCd_1-xThe S solid solution nanosphere is used for hydrogen production by photolysis of water.