CdS-Ag2S composite material, preparation method thereof and application of CdS-Ag2S composite material in photocatalytic degradation of organic dye
The CdS-Ag2S composite material synthesized by the solvothermal method solves the photocorrosion problem of single CdS during photocatalysis, and achieves efficient degradation of organic dyes and has better performance than composite materials with other synthetic methods.
Patent Information
- Application Number
- CN202510133036.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-06
- Publication Date
- 2025-05-27
AI Technical Summary
Single CdS has photocorrosion during photocatalysis, which reduces the photocatalytic performance. In the prior art, no composite materials of cadmium sulfide and silver sulfide are used to degrade organic dyes.
The CdS-Ag2S composite material was synthesized by the solvothermal method, and a mixture of monovalent silver salt, divalent cadmium salt, sulfur source and organic solvent were used to prepare a composite material of spherical cadmium sulfide particles and tetrahedral silver sulfide particles.
It achieves efficient degradation of organic dyes under photocatalytic conditions, and its performance is far superior to that of CdS/Ag2S composite materials obtained by other synthesis methods.
Smart Images
Figure CN120037940A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of photocatalysis, and particularly relates to a CdS-Ag 2 S composite material, a preparation method thereof, and an application thereof in photocatalytic degradation of organic dyes. Background Art
[0002] Ag 2 S nanomaterials are semiconductor materials with excellent optoelectronic and thermoelectric properties, and are widely used in the manufacture of optoelectronic materials, thermoelectric materials and electronic materials. They have broad application prospects in measurement, catalysis, light energy absorption, etc. Ag 2 S can expand the absorption range of visible light and improve the utilization efficiency of visible light because of its relatively narrow band gap. It is widely used in the removal of heavy metals and organic dyes, wastewater purification, etc.
[0003] CdS is a common n-type semiconductor material in the II-VI group, with a band gap of 2.4 eV. Because of its special optical and electrical properties, it has been widely studied and applied in photoluminescence, photoelectric conversion, photocatalytic degradation, photocatalytic hydrogen production, sensor manufacturing, magnetic consumables, biological detection, etc. Existing research shows that the morphology, size and photocatalytic activity of CdS crystals are extremely susceptible to experimental methods. In the existing preparation process of CdS, the solvothermal method not only has low preparation cost, low temperature, high speed, but also requires very little material. Therefore, the solvothermal method has gradually become the primary choice for preparing sulfides.
[0004] However, when single CdS is used for photocatalysis, the photocorrosion phenomenon is very serious, and photo-generated electrons and holes are easily recombined, thereby reducing the photocatalytic performance. At present, in the existing technology, there is no precedent for applying the composite material of cadmium sulfide and silver sulfide to the degradation of organic dyes. Summary of the Invention
[0005] To solve the technical problems existing in the background art, the present invention proposes a CdS-Ag 2 S composite material, which has a high degradation rate for organic dyes under photocatalytic conditions.
[0006] The present invention proposes a preparation method of a CdS-Ag 2 S composite material, wherein the CdS-Ag 2 S composite material is prepared by a solvothermal method from a mixture of a monovalent silver salt, a divalent cadmium salt, a sulfur source and an organic solvent.
[0007] In the present invention, the monovalent silver salt, the divalent cadmium salt, the sulfur source and the organic solvent coexist in the reaction system at the beginning of the reaction, and then an ideal CdS-Ag 2 S composite material is synthesized; the CdS-Ag obtained by this preparation method2 The S composite material has performance far exceeding that of the CdS / Ag 2 composite material obtained by other synthesis methods (Comparative Example 3 or Comparative Example 4).
[0008] The molar ratio of the divalent cadmium salt to the monovalent silver salt is 2 - 10:1;
[0009] Preferably, the molar ratio of the divalent cadmium salt to the monovalent silver salt is 5:1.
[0010] The monovalent silver salt is one of silver nitrate, silver acetate, silver chloride or silver sulfate;
[0011] Preferably, the monovalent silver salt is silver nitrate.
[0012] The divalent cadmium salt is one of cadmium nitrate, cadmium chloride or cadmium sulfate;
[0013] Preferably, the divalent cadmium salt is cadmium nitrate.
[0014] The sulfur source is thiourea.
[0015] The organic solvent is one of dimethylacetamide or dimethylformamide;
[0016] Preferably, the organic solvent is dimethylformamide.
[0017] The reaction temperature of the solvothermal method is 120 - 180 °C, and the reaction time is 2 - 8 h;
[0018] Preferably, the reaction temperature is 150 °C;
[0019] Preferably, the reaction time is 5 h.
[0020] The present invention provides a CdS - Ag 2 S composite material prepared by the above preparation method.
[0021] The CdS - Ag 2 S composite material is composed of spherical cadmium sulfide particles and tetrahedral silver sulfide particles, and the silver sulfide particles are attached to the surface of the cadmium sulfide particles;
[0022] Preferably, the particle size of the silver sulfide particles is 2 - 5 μm, and the particle size of the cadmium sulfide particles is 10 - 30 μm. The present invention also provides an application of the above CdS - Ag 2 S composite material or the CdS - Ag 2 S composite material prepared by the above preparation method in photocatalytic degradation of organic dyes.
[0023] Advantages of the present invention: The CdS - Ag 2The S composite material has a high degradation rate for organic dyes. Description of the Drawings
[0024] Figure 1 CdS-Ag prepared when the molar ratios of cadmium nitrate to silver nitrate are 2:1, 5:1, and 10:1 respectively 2 Scanning electron microscope images of the S composite material, where Figure 1 (a) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 2 (2:1); Figure 1 (b) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 1 (5:1); Figure 1 (c) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 3 (10:1);
[0025] Figure 2 Effect of different reaction times on the CdS-Ag 2 S composite material, where: Figure 2 (a) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 4 (2h); Figure 2 (b) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 5 (4h); Figure 2 (c) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 6 (6h); Figure 2 (d) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 7 (8h);
[0026] Figure 3 Scanning electron microscope image and elemental scanning map of the CdS-Ag 2 S composite material in Example 1, Figure 3 (a) is the scanning electron microscope image of the CdS-Ag 2 S composite material in Example 1; Figure 3 (b) is the corresponding Figure 3 labeled map of the S element in (a); Figure 3 (c) is the corresponding Figure 3 (a) labeled map of the Cd element; Figure (d) is the corresponding Figure 3 labeled map of the Ag element in (a);
[0027] Figure 4 XRD pattern of the CdS-Ag 2 S composite material in Example 1;
[0028] Figure 5For the CdS-Ag in Example 1 2 Energy spectrum diagram of the S composite material;
[0029] Figure 6 (a) Instantaneous change diagram of the absorbance of rhodamine in the photocatalytic experiment of the CdS material in Comparative Example 1; Figure 6 (b) Removal rate curve of the degradation of rhodamine by the CdS powder in Comparative Example 1;
[0030] Figure 7 (a) Instantaneous change diagram of the absorbance of rhodamine in the photocatalytic experiment of the Ag 2 S material in Comparative Example 2; Figure 7 (b) Removal rate curve of the degradation of rhodamine by the Ag 2 S material in Comparative Example 1;
[0031] Figure 8 (a) Instantaneous change diagram of the absorbance of rhodamine in the photocatalytic experiment of the CdS-Ag 2 S composite material in Example 1; Figure 8 (b) Removal rate curve of the degradation of rhodamine by the CdS-Ag 2 S composite material in Comparative Example 1. Detailed implementation manners
[0032] For ease of understanding the present invention, the present invention will be more comprehensively described below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.
[0034] Below, the technical solutions of the present invention will be described more clearly and completely in conjunction with specific examples and comparative examples.
[0035] Example 1
[0036] This example presents a CdS-Ag 2 S composite material, and the specific steps of its preparation method are as follows:
[0037] (1) Weigh 0.500 g of thiourea, 0.236 g of cadmium nitrate, and 0.034 g of silver nitrate respectively, and use an ultrasonic machine to completely dissolve them in 15 mL of DMF organic solution;
[0038] (2) Pour the mixed solution prepared in the above step (1) into a 20 mL reaction kettle, set the oven temperature to 150 °C, and the reaction time to 300 min;
[0039] (3) Naturally cool the reactor in step (2) to room temperature, open the reactor to take out the reactants, wash the reactants by ultrasonic stirring with deionized water 5 times, and then wash with ethanol 2 times to obtain a precipitate powder particle solution. After centrifugal drying, CdS-Ag 2 S composite material.
[0040] Example 2
[0041] This example presents a CdS-Ag 2 S composite material. The specific steps of its preparation method are the same as those in Example 1, except that "weigh 0.500 g of thiourea, 0.236 g of cadmium nitrate, and 0.034 g of silver nitrate" in step (1) is changed to "weigh 0.625 g of thiourea, 0.236 g of cadmium nitrate, and 0.085 g of silver nitrate".
[0042] Example 3
[0043] This example presents a CdS-Ag 2 S composite material. The specific steps of its preparation method are the same as those in Example 1, except that "weigh 0.500 g of thiourea, 0.236 g of cadmium nitrate, and 0.034 g of silver nitrate" in step (1) is changed to "weigh 0.459 g of thiourea, 0.236 g of cadmium nitrate, and 0.017 g of silver nitrate".
[0044] Example 4
[0045] This example presents a CdS-Ag 2 S composite material. The specific steps of its preparation method are the same as those in Example 1, except that "the reaction time is 300 min" in step (2) is changed to "the reaction time is 120 min".
[0046] Example 5
[0047] This example presents a CdS-Ag 2 S composite material. The specific steps of its preparation method are the same as those in Example 1, except that "the reaction time is 300 min" in step (2) is changed to "the reaction time is 240 min".
[0048] Example 6
[0049] This example presents a CdS-Ag 2 S composite material. The specific steps of its preparation method are the same as those in Example 1, except that "the reaction time is 300 min" in step (2) is changed to "the reaction time is 360 min".
[0050] Example 7
[0051] This embodiment provides a CdS-Ag 2 S composite material. The specific steps of its preparation method are the same as those in Embodiment 1, except that "the reaction time is 300 min" in step (2) is changed to "the reaction time is 480 min".
[0052] The CdS-Ag 2 S composite materials prepared in Examples 1-5 were observed by field emission scanning electron microscopy Figure 1 to study the influence of the molar ratios of cadmium nitrate to silver nitrate of 2:1, 5:1, and 10:1 on the scanning electron micrographs of the CdS-Ag 2 S composite materials. Among them:
[0053] Figure 1 (a) is the scanning electron micrograph (2:1) of the CdS-Ag 2 S composite material in Example 2. The product in Example 2 consists of spherical cadmium sulfide and polyhedral silver sulfide; Figure 1 (b) is the scanning electron micrograph (5:1) of the CdS-Ag 2 S composite material in Example 1. The product consists of spherical cadmium sulfide particles and tetrahedral silver sulfide particles. The silver sulfide particles adhere to the surface of the cadmium sulfide particles, and the silver sulfide particles are smaller than the cadmium sulfide particles; Figure 1 (c) is the scanning electron micrograph (10:1) of the CdS-Ag 2 S composite material in Example 3. The obtained product is mainly spherical cadmium sulfide particles, and there are fewer silver sulfide particles.
[0054] Figure 2 To study the influence of different reaction times on the CdS-Ag 2 S composite material. Among them: Figure 2 (a) is the scanning electron micrograph (2 h) of the CdS-Ag 2 S composite material in Example 4. The product consists of spherical cadmium sulfide of different sizes and lamellar silver sulfide; Figure 2 (b) is the scanning electron micrograph (4 h) of the CdS-Ag 2 S composite material in Example 5. The product is composed of different spherical cadmium sulfide assembled into multi-spheres, and the silver sulfide is also in the form of flakes; Figure 2 (c) is the scanning electron micrograph (6 h) of the CdS-Ag 2 S composite material in Example 6. The obtained product is mainly spherical cadmium sulfide, and the silver sulfide particles adhere to the surface of the spherical cadmium sulfide particles; Figure 2 (d) is the scanning electron micrograph of the CdS-Ag 2Scanning electron microscopy image of the composite material (8 h). The product consists of small primary particles that form spherical cadmium sulfide secondary particles of different sizes, while silver sulfide is distributed in an irregular shape on the surface of the spherical cadmium sulfide particles.
[0055] Figure 3 For the CdS-Ag in Example 1 2 Scanning electron microscopy image and elemental mapping of the CdS-Ag Figure 3 (a) Scanning electron microscopy image of the CdS-Ag 2 composite material in Example 1; Figure 3 (b) is the labeled map of the S element corresponding to Figure 3 (a); Figure 3 (c) is the labeled map of the Cd element corresponding to Figure 3 (a); Figure (d) is the labeled map of the Ag element corresponding to Figure 3 (a); The above elemental labeled maps can confirm that Figure 3 (a) the scanned sample is the CdS-Ag 2 composite material; It can be seen from the elemental surface scan map that the S, Cd, and Ag elements have a uniform particle morphology in the CdS-Ag 2 composite material. When generating the CdS-Ag 2 composite material, the interface between cadmium sulfide and silver sulfide is well combined, and the transition of elements is smooth without obvious element enrichment or deficiency.
[0056] Figure 4 XRD pattern of the CdS-Ag 2 composite material prepared in Example 1. After comparison with the standard XRD spectra of CdS and Ag 2 2S, it is further confirmed that the product obtained by the experiment is the CdS-Ag 2 composite material.
[0057] Figure 5 Energy spectrum of the CdS-Ag 2 composite material prepared in Example 1, further proving that the product is composed of Cd, S, and Ag elements without the generation of other impurities.
[0058] Comparative Example 1
[0059] This comparative example presents a CdS material, and the specific steps of its preparation method are as follows:
[0060] (1) Weigh 0.417 g of thiourea and 0.236 g of cadmium nitrate respectively, and use an ultrasonic machine to completely dissolve them in 15 mL of DMF organic solution;
[0061] (2) Load the mixed solution prepared in step (1) into a 20 mL reactor, set the oven temperature to 150 °C, and the reaction time to 300 min;
[0062] (3) Naturally cool the reactor in step (2) to room temperature, open the reactor to take out the reactant, wash the reactant 5 times by ultrasonic stirring with deionized water, and then wash it 2 times with ethanol to obtain a precipitate powder particle solution, and finally centrifuge and dry to obtain CdS material.
[0063] Comparative Example 2
[0064] This comparative example presents an Ag 2 S material, and the specific steps of its preparation method are as follows:
[0065] (1) Weigh 0.083 g of thiourea and 0.034 g of silver nitrate respectively, and use an ultrasonic machine to completely dissolve them in 15 mL of DMF organic solution;
[0066] (2) Load the mixed solution prepared in step (1) into a 20 mL reactor, set the oven temperature to 150 °C, and the reaction time to 300 min;
[0067] (3) Naturally cool the reactor in step (3) to room temperature, open the reactor to take out the reactant, wash the reactant 5 times by ultrasonic stirring with deionized water, and then wash it 2 times with ethanol to obtain a precipitate powder particle solution, and finally centrifuge and dry to obtain Ag 2 S material.
[0068] Comparative Example 3
[0069] This comparative example presents a CdS / Ag 2 S composite material, and the specific steps of its preparation method are as follows:
[0070] Add the CdS powder obtained in Comparative Example 1 and the Ag 2 S powder obtained in Comparative Example 2 to 15 mL of ethanol solution and stir for 3 h to obtain a mixed solution. Transfer the mixed solution to an oven at 80 °C for drying. After the ethanol has completely evaporated, obtain CdS / Ag 2 S composite material.
[0071] Comparative Example 4
[0072] This comparative example presents a CdS / Ag 2 S composite material, and the specific steps of its preparation method are as follows:
[0073] (1) Weigh 0.500 g of thiourea and 0.236 g of cadmium nitrate respectively, and use an ultrasonic machine to completely dissolve them in 15 mL of DMF organic solution;
[0074] (2) Load the mixed solution prepared in the above step (1) into a 20 mL reactor, set the oven temperature to 150 °C, and the reaction time to 300 min;
[0075] (3) Naturally cool the reactor in step (2) to room temperature, then weigh 0.034 g of silver nitrate and add it to the reactant in step (2), and use an ultrasonic machine to completely dissolve the silver nitrate to obtain a mixture;
[0076] (4) Load the mixture obtained in the above step (3) into a 20 mL reactor, set the oven temperature to 150 °C, and the reaction time to 300 min;
[0077] (5) Naturally cool the reactor in step (4) to room temperature, open the reactor to take out the reactant, wash the reactant 5 times by ultrasonic stirring with deionized water, and then wash it 2 times with ethanol to obtain a precipitate powder particle solution, and finally centrifuge and dry to obtain CdS / Ag 2 S composite material.
[0078] Photocatalysis experiment
[0079] (1) Weigh 0.005 g of rhodamine and put it into a 1000 mL volumetric flask to obtain a rhodamine aqueous solution with an initial concentration of 5 mg / L;
[0080] (2) Use a measuring cylinder to measure 80 mL of the rhodamine aqueous solution in step (1) into a beaker, and add 0.020 g of the CdS-Ag 2 S composite material in Example 1 to the beaker to obtain a mixture;
[0081] (3) Stir the mixture in the beaker in step (2) for 30 min, take out the first sample, record it as 0 min, turn on the light source, take a sample every 10 min, take a total of 6 samples, and measure the absorption spectra of the samples respectively, and then calculate the degradation and removal rate of rhodamine.
[0082] After the first photocatalysis experiment is completed, repeat the above operation (2), and replace the "CdS-Ag 2 S composite material in Example 1" with "CdS material in Comparative Example 1", "Ag 2 S material in Comparative Example 2", "CdS / Ag 2 S composite material in Comparative Example 3" and "CdS / Ag 2 S composite material in Comparative Example 4" respectively to complete the remaining 4 photocatalysis experiments.
[0083] Figure 6(a) is the instantaneous change diagram of the absorbance of rhodamine in the photocatalytic experiment of the CdS material in Comparative Example 1. At this time, the absorption wavelength corresponding to rhodamine is approximately 550 nm. As the photocatalytic time prolongs, the absorbance of rhodamine gradually decreases; Figure 6 (b) is the removal rate curve diagram of the degradation of rhodamine by the CdS powder in Comparative Example 1. It can be seen from the curve diagram that the degradation rate of rhodamine by the CdS powder is relatively fast in the time period of 0 - 20 min, and the degradation rate slows down after 20 min.
[0084] Figure 7 (a) is for Ag in Comparative Example 2 2 The instantaneous change diagram of the absorbance of rhodamine in the photocatalytic experiment of the S material. At this time, the absorption wavelength corresponding to rhodamine is approximately 560 nm. As the photocatalytic time prolongs, the absorbance of rhodamine gradually decreases; Figure 7 (b) is for Ag in Comparative Example 1 2 The removal rate curve diagram of the degradation of rhodamine by the S material. It can be seen from the curve diagram that the degradation rate of rhodamine by the CdS powder is relatively fast in the time period of 0 - 20 min, and the degradation rate slows down after 20 min.
[0085] Figure 8 (a) is the instantaneous change diagram of the absorbance of rhodamine in the photocatalytic experiment of the CdS - Ag 2 S composite material in Example 1. At this time, the absorption wavelength corresponding to rhodamine is approximately 560 nm. As the photocatalytic time prolongs, the absorbance of rhodamine gradually decreases; Figure 8 (b) is for CdS - Ag in Comparative Example 1 2 The removal rate curve diagram of the degradation of rhodamine by the S composite material. It can be seen from the curve diagram that the CdS - Ag 2 S composite material maintains a relatively fast degradation rate of rhodamine during the time period of 0 - 50 min.
[0086] Calculate the degradation rates of rhodamine by the above different catalytic materials. Table 1 shows the degradation rates of rhodamine by different photocatalytic materials (150 min).
[0087] Table 1 Degradation rates of rhodamine by different photocatalytic materials
[0088] Photocatalytic material Degradation rate of rhodamine CdS material in Comparative Example 1 45.3％ <![CDATA[Ag in Comparative Example 2 2 S material]]> 13.7％ <![CDATA[CdS / Ag in Comparative Example 3 2 S composite material]]> 47.8％ <![CDATA[CdS / Ag in Comparative Example 4 2 S composite material]]> 52.9％ <![CDATA[CdS-Ag in Example 1 2 S composite material]]> 90.3％
[0089] It can be seen from Table 1 that when the CdS material or Ag 2 S material exists alone, the degradation rate of rhodamine is not high; when the CdS / Ag 2 S composite material is prepared by other methods, its degradation rate of rhodamine increases, but not significantly; while the CdS - Ag 2 S composite material obtained by the preparation methods described in Examples 1 - 7 has a very good degradation rate for rhodamine.
[0090] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.
Claims
1. A method for preparing a CdS-Ag2S composite material, characterized in that: The CdS-Ag2S composite material is prepared by a solvothermal method on a mixture of a monovalent silver salt, a divalent cadmium salt, a sulfur source and an organic solvent.
2. The method for preparing the CdS-Ag2S composite material according to claim 1, characterized in that: The molar ratio of the divalent cadmium salt to the monovalent silver salt is 2-10:1; Preferably, the molar ratio of the divalent cadmium salt to the monovalent silver salt is 5:
1.
3. The method for preparing the CdS-Ag2S composite material according to claim 1 or 2, characterized in that: The monovalent silver salt is one of silver nitrate, silver acetate, silver chloride or silver sulfate; Preferably, the monovalent silver salt is silver nitrate.
4. The method for preparing the CdS-Ag2S composite material according to any one of claims 1 to 3, characterized in that: The divalent cadmium salt is one of cadmium nitrate, cadmium chloride or cadmium sulfate; Preferably, the divalent cadmium salt is cadmium nitrate.
5. The method for preparing the CdS-Ag2S composite material according to any one of claims 1 to 4, characterized in that: The sulfur source is thiourea.
6. The method for preparing the CdS-Ag2S composite material according to any one of claims 1 to 5, characterized in that: The organic solvent is one of dimethylacetamide or dimethylformamide; Preferably, the organic solvent is dimethylformamide.
7. The method for preparing the CdS-Ag2S composite material according to any one of claims 1 to 6, characterized in that: The reaction temperature of the solvent thermal method is 120-180°C and the reaction time is 2-8h; Preferably, the reaction temperature is 150°C; Preferably, the reaction time is 5 h.
8. A CdS-Ag2S composite material prepared by the preparation method according to any one of claims 1 to 7.
9. The CdS-Ag2S composite material according to claim 8, characterized in that: The CdS-Ag2S composite material is composed of spherical cadmium sulfide particles and tetrahedral silver sulfide particles, and the silver sulfide particles are attached to the surface of the cadmium sulfide particles; Preferably, the silver sulfide particles have a particle size of 2-5 μm, and the cadmium sulfide particles have a particle size of 10-30 μm.
10. Use of the CdS-Ag2S composite material prepared by the preparation method according to any one of claims 1 to 7 or the CdS-Ag2S composite material according to claim 8 or 9 in photocatalytic degradation of organic dyes.