A method for preparing semiconductor ion gel microspheres

Abstract

This invention discloses a method for preparing semiconductor ionogel microspheres, comprising the following steps: dissolving acrylamide (AM), a crosslinking agent, an ionic liquid, and an aqueous solution of CdS quantum dots by stirring to obtain an aqueous phase; mixing an emulsifier with cyclohexane and stirring to prepare an oil phase; adding the aqueous phase dropwise to the oil phase, sonicating, adding an initiator, heating in an oil bath to fully react, vacuum drying, washing, and then drying again to obtain semiconductor ionogel microspheres. This invention uses acrylamide as a monomer to prepare reverse emulsion microspheres and uses an ionic liquid to enhance the catalytic activity of CdS quantum dot semiconductors. The presence of the ionic liquid significantly improves the ability of semiconductor quantum dots in photocatalytic applications. The preparation method of this invention is simple, has a short preparation cycle, and low equipment cost, making it suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of ion gel composite material preparation technology, and in particular relates to a method for preparing semiconductor ion gel microspheres. Background Technology

[0002] Ionic gels, composed of ionic liquids and supporting networks, exhibit a variety of superior properties, such as high mechanical strength, excellent ionic conductivity, significant thermal and electrochemical stability, and non-volatility. These unique properties enable ionic gels to be widely used in functional materials, sensors, flexible electronics, solid electrolytes, and biomedicine. Ionic liquid gels are prepared by confining ionic liquids within a polymer network.

[0003] CdS semiconductor quantum dots are promising photocatalysts, but they also have inherent drawbacks. For example, their high surface energy leads to agglomeration, affecting their catalytic performance and hindering recycling. Furthermore, photocorrosion, a common problem in semiconductor materials, is particularly severe in quantum dots, impacting their reusability. It has been reported that ionic liquids can effectively prevent photocorrosion of quantum dot semiconductors. Summary of the Invention

[0004] The purpose of this invention is to address the technical challenges of low catalytic efficiency of semiconductor quantum dots and susceptibility of semiconductors to photocorrosion, and to provide a method for preparing ion gel composite materials. This method can also effectively prevent the loss of ion liquids, resulting in an ion liquid gel composite material.

[0005] To achieve the above-mentioned objectives of this invention, the preparation method of a semiconductor ion gel microsphere of this invention is implemented by the following steps:

[0006] (1) Preparation of semiconductor quantum dot solution: Add CdCl2·2.5H2O and 3-mercaptopropionic acid to a certain amount of water and stir until fully dissolved. Add 30% NaOH solution to adjust pH to >10.

[0007] (2) Deoxygenation reaction: The solution is placed in a flask and nitrogen gas is introduced for a certain period of time. A certain amount of Na2S is added and heated. After the reaction is completed, the temperature naturally drops.

[0008] (3) Separation and impurity removal: Add a certain volume of acetone to the solution, centrifuge and wash repeatedly to obtain CdS semiconductor quantum dots and prepare an aqueous solution of CdS semiconductor quantum dots;

[0009] (4) Mixing: Ionic liquid, acrylamide, and N,N-methylenebisacrylamide are added to a certain amount of CdS semiconductor quantum dot aqueous solution and ultrasonically mixed to form an aqueous phase. A certain amount of Span 80 and Tx-100 are added to cyclohexane and ultrasonically mixed to form an oil phase. The aqueous phase is slowly dripped into the oil phase and then ultrasonically mixed.

[0010] (5) Reverse emulsion polymerization: The above-mentioned oil bath is heated and polymerized for a certain time, and then naturally cooled to room temperature;

[0011] (6) Washing and drying: Add ethanol to the obtained emulsion, stir, centrifuge, wash repeatedly, and freeze dry.

[0012] As a preferred embodiment of the above preparation method, in step (1), the molar ratio of CdCl2·2.5H2O to 3-mercaptopropionic acid is 1:1.2 to 1:3.

[0013] As a preferred embodiment of the above preparation method, in step (1), the molar ratio of CdCl2·2.5H2O to water after pH adjustment is 1:1000 to 1:2000.

[0014] As a preferred embodiment of the above preparation method, in step (2), the molar ratio of CdCl2·2.5H2O to Na2S is 1:0.8 to 1:1.2.

[0015] As a preferred embodiment of the above preparation method, in step (3), the volume ratio of the solution to the acetone solution is 1:1.2 to 1:2.

[0016] As a preferred embodiment of the above preparation method, in step (3), the amount of water added to prepare the aqueous solution is more than 200 times the molar amount of CdCl2·2.5H2O.

[0017] As a preferred embodiment of the above preparation method, in step (4), the mass ratio of acrylamide to ionic liquid is configured to be 2:1 to 6:1.

[0018] As a preferred embodiment of the above preparation method, the mass ratio of acrylamide to N,N-methylenebisacrylamide in step (4) is 200:1 to 50:1.

[0019] As a preferred embodiment of the above preparation method, the mass ratio of acrylamide to CdS semiconductor quantum dot aqueous solution in step (4) is 1:2 to 1:3.

[0020] As a preferred embodiment of the above preparation method, the mass ratio of Span 80 to Tx-100 in step (4) is 5:1 to 3:1.

[0021] As a preferred embodiment of the above preparation method, the volume ratio of the aqueous phase to the oil phase in step (4) is 2.5:1 to 5:1.

[0022] As a preferred embodiment of the above preparation method, the heating temperature in step (5) is 70-75°C and the polymerization time is 3-6 h.

[0023] Compared with existing technologies, this invention provides a method for preparing semiconductor ion gel microspheres, which has the following beneficial effects:

[0024] This invention uses CdCl2·2.5H2O as the cadmium source, 3-mercaptopropionic acid as the ligand, adjusts the pH with NaOH solution, heats the reaction and uses water as the solvent to simply prepare CdS semiconductor quantum dots.

[0025] This invention uses acrylamide as a monomer to polymerize and form a polymer network structure, which confines the ionic liquid within the channels of mesoporous titanium dioxide, thereby improving the catalytic ability of semiconductor quantum dots.

[0026] This invention employs reverse emulsion polymerization to successfully prepare semiconductor ion gel composite microspheres with large specific surface area, low fluidity, and resistance to leaching and loss of ionic liquids.

[0027] The preparation process of this invention is simple, the preparation cycle is short, the preparation cost is low, and it can be adapted to large-scale production. Attached Figure Description

[0028] Figure 1 These are SEM images of the semiconductor ion gel microspheres prepared in Examples 1 and 2 of the present invention.

[0029] Figure 2 This is a TEM image of the semiconductor ion gel microspheres prepared in Example 1 of the present invention;

[0030] Figure 3 Here is the FT-IR image of the semiconductor ion gel microspheres prepared by the method of Example 1 of the present invention and its constituent materials;

[0031] Figure 4 This is a Zeta potential diagram of the semiconductor ion gel microspheres prepared by Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. Detailed Implementation

[0032] To describe the present invention, the preparation method of a semiconductor ion gel microsphere according to the present invention will be further described in detail below with reference to embodiments. However, the present invention is not limited to the embodiments.

[0033] Example 1

[0034] (1) Preparation of semiconductor quantum dot solution: Add 4 mmol CdCl2·2.5H2O and 6.8 mol 3-mercaptopropionic acid to 4.4 mmol of water and stir until fully dissolved. Add 30% NaOH solution to adjust pH to >10.

[0035] (2) Deoxygenation reaction: The solution is placed in a flask and nitrogen gas is introduced for a certain period of time. 4 mmol of Na2S is added and heated. The reaction is completed and the temperature is naturally lowered.

[0036] (3) Separation and impurity removal: Add a certain volume of acetone to the solution, centrifuge and wash repeatedly. The volume ratio of acetone to water during washing should be greater than 1.5. After obtaining CdS semiconductor quantum dots, prepare an aqueous solution of CdS semiconductor quantum dots.

[0037] (4) Mixing: Ionic liquid, acrylamide, and N,N-methylenebisacrylamide were added to a certain amount of CdS semiconductor quantum dot aqueous solution and ultrasonically mixed to form an aqueous phase. The ionic liquid used was [Bmim]BF4, with acrylamide weighing 4g, ionic liquid weighing 1g, N,N-methylenebisacrylamide weighing 0.04g, and CdS semiconductor quantum dot aqueous solution weighing 10g. A certain amount of Span 80 and Tx-100 were added to cyclohexane and ultrasonically mixed to form an oil phase. The aqueous phase was then slowly added dropwise to the oil phase and ultrasonically mixed. The mass of Span 80 was 3.2g, the mass of Tx-100 was 0.8g, and the volume of cyclohexane was 25ml.

[0038] (5) Reverse emulsion polymerization: The mixed solution was heated to 70°C in an oil bath for 5 hours and then naturally cooled to room temperature;

[0039] (6) Washing and drying: The obtained emulsion was washed three times with ethanol and dried in a vacuum drying oven at 50°C for 12 hours.

[0040] Example 2

[0041] (1) Preparation of semiconductor quantum dot solution: Add 4 mmol CdCl2·2.5H2O and 6.8 mol 3-mercaptopropionic acid to 4.4 mmol of water and stir until fully dissolved. Add 30% NaOH solution to adjust pH to >10.

[0042] (2) Deoxygenation reaction: The solution is placed in a flask and nitrogen gas is introduced for a certain period of time. 4 mmol of Na2S is added and heated. The reaction is completed and the temperature is naturally lowered.

[0043] (3) Separation and impurity removal: Add a certain volume of acetone to the solution, centrifuge and wash repeatedly. The volume ratio of acetone to water during washing should be greater than 1.5. After obtaining CdS semiconductor quantum dots, prepare an aqueous solution of CdS semiconductor quantum dots.

[0044] (4) Mixing: Ionic liquid, acrylamide, and N,N-methylenebisacrylamide were added to a certain amount of CdS semiconductor quantum dot aqueous solution and ultrasonically mixed to form an aqueous phase. The ionic liquid used was [Bmim]BF4, with acrylamide weighing 4g, ionic liquid weighing 1.5g, N,N-methylenebisacrylamide weighing 0.04g, and CdS semiconductor quantum dot aqueous solution weighing 10g. A certain amount of Span 80 and Tx-100 were added to cyclohexane and ultrasonically mixed to form an oil phase. The aqueous phase was then slowly added dropwise to the oil phase and ultrasonically mixed. The mass of Span 80 was 3.2g, the mass of Tx-100 was 0.8g, and the volume of cyclohexane was 30ml.

[0045] (5) Reverse emulsion polymerization: The mixed solution was heated to 70°C in an oil bath for 5 hours and then naturally cooled to room temperature;

[0046] (6) Washing and drying: The obtained emulsion was washed three times with ethanol and dried in a vacuum drying oven at 50°C for 12 hours.

[0047] Compare with Example 1

[0048] (1) Mixing: Acrylamide and N,N-methylenebisacrylamide were added to an aqueous solution and sonicated to form an aqueous phase. The mass of water in the acrylamide aqueous solution was 10g, the mass of acrylamide was 4g, and the mass of N,N-methylenebisacrylamide was 0.04g. A certain amount of Span 80 and Tx-100 were added to cyclohexane and sonicated to form an oil phase. The aqueous phase was then slowly added dropwise to the oil phase and sonicated to mix. The mass of Span 80 was 3.2g, the mass of Tx-100 was 0.8g, and the volume of cyclohexane was 25ml.

[0049] (2) Reverse emulsion polymerization: The mixed solution was heated to 70°C in an oil bath for 5 hours.

[0050] (3) Washing and drying: The obtained emulsion was washed three times with ethanol and dried in a vacuum drying oven at 50°C for 12 hours.

[0051] Compare with Example 2

[0052] (1) Mixing: Ionic liquid, acrylamide, and N,N-methylenebisacrylamide were added to an aqueous solution and sonicated to form an aqueous phase. The ionic liquid used was [Bmim]BF4. The mass of water was 10g, the mass of acrylamide was 4g, the mass of ionic liquid was 1g, and the mass of N,N-methylenebisacrylamide was 0.04g. A certain amount of Span 80 and Tx-100 were added to cyclohexane and sonicated to form an oil phase. The aqueous phase was then slowly added dropwise to the oil phase and sonicated to mix. The mass of Span 80 was 3.2g, the mass of Tx-100 was 0.8g, and the volume of cyclohexane was 25ml.

[0053] (2) Reverse emulsion polymerization: The mixed solution was heated to 70°C in an oil bath for 5 hours.

[0054] (3) Washing and drying: The obtained emulsion was washed three times with ethanol and dried in a vacuum drying oven at 50°C for 12 hours.

[0055] Compare with Example 3

[0056] (1) Preparation of semiconductor quantum dot solution: Add 4 mmol CdCl2·2.5H2O and 6.8 mol 3-mercaptopropionic acid to 4.4 mmol of water and stir until fully dissolved. Add 30% NaOH solution to adjust pH to >10.

[0057] (2) Deoxygenation reaction: The solution is placed in a flask and nitrogen gas is introduced for a certain period of time. 4 mmol of Na2S is added and heated. The reaction is completed and the temperature is naturally lowered.

[0058] (3) Separation and impurity removal: Add a certain volume of acetone to the solution, centrifuge and wash repeatedly. The volume ratio of acetone to water during washing should be greater than 1.5. After obtaining CdS semiconductor quantum dots, prepare an aqueous solution of CdS semiconductor quantum dots.

[0059] (4) Mixing: Acrylamide and N,N-methylenebisacrylamide were added to a certain amount of CdS semiconductor quantum dot aqueous solution and ultrasonically mixed to form an aqueous phase. The mass of acrylamide was 4g, the mass of N,N-methylenebisacrylamide was 0.04g, and the mass of CdS semiconductor quantum dot aqueous solution was 10g. A certain amount of Span 80 and Tx-100 were added to cyclohexane and ultrasonically mixed to form an oil phase. The aqueous phase was then slowly added dropwise to the oil phase and ultrasonically mixed. The mass of Span 80 was 3.2g, the mass of Tx-100 was 0.8g, and the volume of cyclohexane was 25ml.

[0060] (5) Reverse emulsion polymerization: The mixed solution was heated to 70°C in an oil bath for 5 hours and then naturally cooled to room temperature;

[0061] (6) Washing and drying: The obtained emulsion was washed three times with ethanol and dried in a vacuum drying oven at 50°C for 12 hours.

[0062] Figure 1 SEM images of the semiconductor ion gel microspheres prepared in Examples 1 and 2 (Figure A: Example 1, Figure B: Example 2). As the content of ion liquid increases, the semiconductor gel microspheres gradually become more viscous from being relatively dispersed, and microspherical semiconductor gel polymers were successfully prepared.

[0063] Figure 2Transmission electron microscopy (TEM) of the semiconductor ion gel microspheres prepared in Example 1 showed that the prepared CdS-MPA was distributed on the gel microspheres, indicating that CdS-MPA was successfully loaded onto the semiconductor gel microspheres.

[0064] Figure 3 FT-IR image of the semiconductor ionogel microspheres prepared in Example 1 and its constituent materials. Analysis revealed that the ionogel microspheres were located at 2566 cm⁻¹ in 3-mercaptopropionic acid. -1 The disappearance of the SH bond at this location indicates that the SH bond has broken. Simultaneously, we observed at 1718 cm... -1 A strong peak appears at 1718 cm⁻¹, which is due to the stretching vibration of C=O. This peak disappears in quantum dots, leading us to speculate that the -COOH group in the ligand molecule has also changed, producing sodium carboxylate. Sodium carboxylate has a peak at 1718 cm⁻¹. -1 No absorption, but at 1604 and 1403 cm⁻¹ -1 A doublet of two carbonyl peaks resembling those of carboxylic acids appeared at [1052 cm⁻¹]. Simultaneously, we detected [Bmim]BF₄ at 1052 cm⁻¹ in the FT-IR of Example 1. -1 The broad peak of BF at the location indicates that the product obtained in Example 1 contains the substance [Bmim]BF4, and the product was successfully prepared in the end.

[0065] Figure 4 The figures show the Zeta potential analysis results for Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. Zeta potential reflects the surface charge density of colloidal particles. Changes in the Zeta potential of the material surface can determine whether charged components have incorporated into the matrix material. The Zeta potential of Comparative Example 1 was -10.51 mV. After loading [Bmim]BF4 onto PAM, the surface potential of Control Group 2 was -2.23 mV, an increase of 8.28 mV compared to Comparative Example 1. This indicates that the doping of ionic liquids increases the potential of the product. Similarly, when CdS-MPA was added, the surface potential of Comparative Example 3 decreased by 9.66 mV compared to Comparative Example 1, indicating that the presence of CdS-MPA lowered its surface potential.

Claims

1. A method for preparing semiconductor ion gel microspheres, characterized in that, Includes the following steps: (1) Preparation of semiconductor quantum dot solution: Add CdCl2·2.5H2O and 3-mercaptopropionic acid to a certain amount of water and stir until fully dissolved. Add 30% NaOH solution to adjust pH to >10. (2) Deoxygenation reaction: The solution is placed in a flask and nitrogen gas is introduced for a certain period of time. A certain amount of Na2S is added and heated. After the reaction is completed, the temperature naturally drops. (3) Separation and impurity removal: Add a certain volume of acetone to the solution, centrifuge and wash repeatedly to obtain CdS semiconductor quantum dots and then prepare an aqueous solution of CdS semiconductor quantum dots; (4) Mixing: Ionic liquid, acrylamide, and N,N-methylenebisacrylamide are added to a certain amount of CdS semiconductor quantum dot aqueous solution and ultrasonically mixed to form an aqueous phase. A certain amount of Span 80 and Tx-100 are added to cyclohexane and ultrasonically mixed to form an oil phase. The aqueous phase is then slowly added dropwise to the oil phase and ultrasonically mixed. (5) Reverse emulsion polymerization: The above mixed solution is heated in an oil bath for a certain time and then naturally cooled to room temperature; (6) Washing and drying: Add ethanol to the obtained emulsion, stir, centrifuge, wash repeatedly, and dry in a vacuum oven.

2. The method for preparing semiconductor ionogel microspheres as described in claim 1, characterized in that, In step (1), the molar ratio of CdCl2·2.5H2O to 3-mercaptopropionic acid is 1:1.2~1:

3.

3. The method for preparing semiconductor ionogel microspheres as described in claim 1, characterized in that, In step (1), the molar ratio of CdCl2·2.5H2O to water after pH adjustment is 1:1000~1:2000.

4. The method for preparing semiconductor ionogel microspheres as described in claim 1, characterized in that, In step (2), the molar ratio of CdCl2·2.5H2O to Na2S is 1:0.8~1:1.

2. In step (3), the amount of water added to the aqueous solution is more than 200 times the amount of CdCl2·2.5H2O.

5. The method for preparing semiconductor ionogel microspheres as described in claim 1, characterized in that, In step (4), the ionic liquid is [Bmim]BF4.

6. The method for preparing semiconductor ionogel microspheres as described in claim 1, characterized in that, In step (4), the mass ratio of acrylamide to ionic liquid is configured to be 2:1 to 6:1, the mass ratio of acrylamide to N,N-methylenebisacrylamide is configured to be 200:1 to 50:1, and the mass ratio of acrylamide to CdS semiconductor quantum dot aqueous solution is configured to be 1:2 to 1:

3.

7. The method for preparing semiconductor ionogel microspheres as described in claim 1, characterized in that, In step (4), the mass ratio of Span 80 to Tx-100 is configured to be 5:1 to 3:

1.

8. The method for preparing semiconductor ionogel microspheres as described in claim 1, characterized in that, In step (4), the volume ratio of the added aqueous phase to the oil phase is configured to be 2.5:1 to 5:

1.

9. The method for preparing semiconductor ion gel microspheres as described in claim 1, characterized in that, In step (5), the heating temperature is 70~75℃ and the polymerization time is 3~6 h.

Images