A method and application of photochemical synthesis of zinc sulfide and cadmium sulfide composite materials using a two-step method

Abstract

This invention belongs to the field of photocatalytic degradation technology, specifically relating to a two-step photochemical synthesis method and application of zinc sulfide and cadmium sulfide composite materials. The invention provides a two-step photochemical synthesis method for zinc sulfide and cadmium sulfide composite materials. The first step involves using an aqueous solution of cadmium sulfate and sodium thiosulfate as a precursor solution, which is then irradiated under ultraviolet light to prepare a cadmium sulfide matrix material. The second step involves preparing an aqueous solution of zinc sulfate, sodium thiosulfate, and the aforementioned cadmium sulfide matrix material, which is then irradiated under ultraviolet light to obtain the zinc sulfide and cadmium sulfide composite material. Using this composite material as a photocatalyst for the photocatalytic degradation of Rhodamine B dye under blue light, the degradation performance is significantly improved compared to monomeric cadmium sulfide, and it exhibits better repeatability and stability, thus improving the photocatalytic degradation performance of current sulfide catalysts. Furthermore, the method is easy to operate, environmentally friendly, and conducive to large-scale production applications.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic degradation technology, specifically relating to a two-step photochemical synthesis method and application of zinc sulfide and cadmium sulfide composite materials. Background Technology

[0002] Cadmium sulfide (CdS) is an n-type semiconductor with a band gap of ~2.4 eV. Due to its excellent photochemical properties and nonlinear characteristics in the visible light region, it has attracted considerable attention in fields such as photoelectric conversion in solar cells, light-emitting diodes (LEDs), LED light-emitting materials, lasers, and thin-film transistors. Furthermore, CdS can be modified with other semiconductors, noble metals, or dopants to further improve its photogenerated carrier separation efficiency, thereby enhancing photocatalytic efficiency and achieving highly efficient catalysis. In recent years, increasing research has focused on combining CdS with other semiconductors to construct heterostructures to improve photocatalytic efficiency; however, the synthesis methods are complex and relatively environmentally unfriendly. Therefore, it is necessary to develop new synthesis methods to simplify the preparation of CdS composite materials while making them more environmentally friendly. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this invention provides a two-step photochemical synthesis method for zinc sulfide and cadmium sulfide composite materials that can catalytically degrade organic dyes under visible light. This method not only improves the photocatalytic degradation performance of current sulfide catalysts, but also is easy to operate, low in cost, environmentally friendly, and the synthesis conditions are readily available, which is conducive to large-scale production and application.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] The first aspect of this invention provides a two-step photochemical synthesis method for zinc sulfide and cadmium sulfide composite materials, comprising the following steps:

[0006] S1. First, prepare a precursor solution containing both cadmium and sulfur sources. Then, treat the precursor solution with ultraviolet light under stirring to obtain a cadmium sulfide matrix.

[0007] The obtained cadmium sulfide particles are uniformly distributed and do not show obvious agglomeration, which is helpful for the second step of synthesizing zinc sulfide and cadmium sulfide composite materials.

[0008] S2. First, prepare a mixed solution containing both zinc and sulfur sources, then add the cadmium sulfide matrix obtained in step S1 to form a precursor solution. Then, under stirring, treat the precursor solution with ultraviolet light again to obtain the zinc sulfide and cadmium sulfide composite material.

[0009] This invention utilizes a two-step photochemical synthesis of a zinc sulfide and cadmium sulfide composite material. This method is not only easy to operate, low in cost, and environmentally friendly, but also readily available in terms of synthesis conditions, which is conducive to large-scale production and application. Furthermore, it further improves the photocatalytic degradation performance of current sulfide catalysts, with a significant improvement in degradation performance compared to monomeric cadmium sulfide, and exhibits good repeatability and stability.

[0010] Preferably, in step S1, the concentration of the cadmium source is 0.7-1.1 mol / L, and the concentration of the sulfur source is 0.1-0.3 mol / L. More preferably, the ratio of the cadmium source to the sulfur source is 4.5:1.

[0011] Preferably, in step S2, the concentration of the zinc source is 0.7-1.1 mol / L, the concentration of the sulfur source is 0.1-0.3 mol / L, and the concentration of cadmium sulfide is 0.3-0.5 mmol / L.

[0012] Preferably, the cadmium source includes (but is not limited to) cadmium sulfate, the sulfur source includes (but is not limited to) sodium thiosulfate, and the zinc source includes (but is not limited to) zinc sulfate.

[0013] Preferably, in the ultraviolet irradiation treatment of step S1 or S2, the light intensity on the surface of the precursor liquid is 0.25-0.30 mw / cm². 2 The processing time is 6-24 hours.

[0014] Preferably, in step S1 or S2, the stirring speed is 300-500 r / min.

[0015] The second aspect of the present invention provides a zinc sulfide and cadmium sulfide composite material prepared by the method described in the first aspect.

[0016] The third aspect of this invention provides the application of the zinc sulfide and cadmium sulfide composite materials described in the second aspect in the photocatalytic degradation of organic dyes.

[0017] Preferably, the organic dye includes (but is not limited to) rhodamine B.

[0018] The fourth aspect of the present invention provides a method for photocatalytic degradation of organic dyes, specifically: adding the zinc sulfide and cadmium sulfide composite material described in the second aspect to a solution containing organic dyes, first performing dark adsorption in a dark environment for more than half an hour, and then performing photocatalytic degradation under blue light irradiation for no less than 1 hour.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention provides a method for preparing a photochemically synthesized zinc sulfide and cadmium sulfide composite material. The first step involves forming a cadmium sulfide matrix using sodium thiosulfate as a sulfur source and cadmium sulfate as a cadmium source under ultraviolet light. The second step involves reacting the cadmium sulfide matrix obtained in the first step with the sulfur source provided by sodium thiosulfate and the zinc source provided by zinc sulfate under ultraviolet light to form a binary composite material, namely, the zinc sulfide and cadmium sulfide composite material. In terms of photocatalytic degradation of organic dyes, this composite material exhibits significantly improved degradation performance compared to monomeric cadmium sulfide, and also demonstrates excellent stability and repeatability, thus improving the current photocatalytic degradation performance of sulfides. Furthermore, this two-step photochemical synthesis method for the zinc sulfide and cadmium sulfide composite material is environmentally friendly, can be completed at room temperature, and is simple to operate, facilitating large-scale production applications. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the zinc sulfide and cadmium sulfide composite material synthesized by the two-step photochemical method in Example 5.

[0022] Figure 2 Scanning electron microscope (SEM) images of the cadmium sulfide matrix materials in Examples 1-4;

[0023] Figure 3 A comparison of the degradation performance of zinc sulfide and cadmium sulfide composite materials synthesized by a two-step photochemical method and cadmium sulfide monomers on rhodamine B.

[0024] Figure 4 The graph shows the response of catalyst concentration to degradation performance in the photocatalytic degradation of Rhodamine B by the zinc sulfide and cadmium sulfide composite materials synthesized by the two-step photochemical method.

[0025] Figure 5 The repeatability of the two-step photochemically synthesized zinc sulfide and cadmium sulfide composite materials for the degradation of rhodamine B is shown in the graph and its linear fitting graph.

[0026] Figure 6 The results show a comparison of the degradation performance of zinc sulfide and cadmium sulfide composite materials synthesized by the traditional hydrothermal method and the two-part photochemical method on rhodamine B. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0029] Example 1 Preparation of cadmium sulfide matrix

[0030] (1) 2.48 g of sodium thiosulfate and 11.54 g of cadmium sulfate powder were placed in beakers respectively, and 20 mL and 30 mL of water were added respectively to dissolve them by sonication for half an hour. The mixture was stirred evenly with a glass rod. Then the sodium thiosulfate solution was slowly added to the cadmium sulfate solution and stirred with a glass rod to mix them thoroughly to obtain the precursor solution. The concentration of sodium thiosulfate in the precursor solution was 0.2 mol / L and the concentration of cadmium sulfate was 0.9 mol / L.

[0031] (2) Transfer the precursor solution to a 10 cm diameter petri dish, add a 5 cm long cylindrical magnetic stir bar to the petri dish, and place two 8 W UV lamps parallel above the petri dish (vertically 4.5 cm apart) to make the light intensity above the liquid surface 0.277 mw / cm². 2 Then, under magnetic stirring at 350 r / min, the reaction was continuously irradiated for 6 h. After the reaction was stopped, the reaction product was washed by centrifugation, transferred to a petri dish of appropriate size, and dried in an oven for 12 h to obtain the photochemically synthesized cadmium sulfide matrix.

[0032] Example 2 Preparation of cadmium sulfide matrix

[0033] (1) 2.48 g of sodium thiosulfate and 11.54 g of cadmium sulfate powder were placed in beakers respectively, and 20 mL and 30 mL of water were added respectively to dissolve them by sonication for half an hour. The mixture was stirred evenly with a glass rod. Then the sodium thiosulfate solution was slowly added to the cadmium sulfate solution and stirred with a glass rod to mix them thoroughly to obtain the precursor solution. The concentration of sodium thiosulfate in the precursor solution was 0.2 mol / L and the concentration of cadmium sulfate was 0.9 mol / L.

[0034] (2) Transfer the precursor solution to a 10 cm diameter petri dish, add a 5 cm long cylindrical magnetic stir bar to the petri dish, and place two 8 W UV lamps parallel above the petri dish (vertically 4.5 cm apart) to make the light intensity above the liquid surface 0.277 mw / cm². 2 Then, under magnetic stirring at 350 r / min, the reaction was continuously irradiated for 12 h. After the reaction was stopped, the reaction product was washed by centrifugation, transferred to a petri dish of appropriate size, and dried in an oven for 12 h to obtain the photochemically synthesized cadmium sulfide matrix.

[0035] (1) 2.48 g of sodium thiosulfate and 11.54 g of cadmium sulfate powder were placed in beakers respectively, and 20 mL and 30 mL of water were added respectively to dissolve them by sonication for half an hour. The mixture was stirred evenly with a glass rod. Then the sodium thiosulfate solution was slowly added to the cadmium sulfate solution and stirred with a glass rod to mix them thoroughly to obtain the precursor solution. The concentration of sodium thiosulfate in the precursor solution was 0.2 mol / L and the concentration of cadmium sulfate was 0.9 mol / L.

[0036] (2) Transfer the precursor solution to a 10 cm diameter petri dish, add a 5 cm long cylindrical magnetic stir bar to the petri dish, and place two 8 W UV lamps parallel above the petri dish (vertically 4.5 cm apart) to make the light intensity above the liquid surface 0.277 mw / cm². 2 Then, under magnetic stirring at 350 r / min, the reaction was continuously irradiated for 12 h. After the reaction was stopped, the reaction product was washed by centrifugation, transferred to a petri dish of appropriate size, and dried in an oven for 12 h to obtain the photochemically synthesized cadmium sulfide matrix.

[0037] Example 3 Preparation of cadmium sulfide matrix

[0038] (1) 2.48 g of sodium thiosulfate and 11.54 g of cadmium sulfate powder were placed in beakers respectively, and 20 mL of water and 30 mL of water were added respectively to dissolve them by sonication for half an hour. The mixture was stirred evenly with a glass rod. Then the sodium thiosulfate solution was slowly added to the cadmium sulfate solution and stirred with a glass rod to mix them thoroughly to obtain the precursor solution. The concentration of sodium thiosulfate in the precursor solution was 0.2 mol / L and the concentration of cadmium sulfate was 0.9 mol / L.

[0039] (2) Transfer the precursor solution to a 10 cm diameter petri dish, add a 5 cm long cylindrical magnetic stir bar to the petri dish, and place two 8 W UV lamps parallel above the petri dish (vertically 4.5 cm apart) to make the light intensity above the liquid surface 0.277 mw / cm². 2 Then, under magnetic stirring at 350 r / min, the reaction was continuously irradiated for 18 h. After the reaction was stopped, the reaction product was washed by centrifugation, transferred to a petri dish of appropriate size, and dried in an oven for 12 h to obtain the photochemically synthesized cadmium sulfide matrix.

[0040] Example 4 Preparation of cadmium sulfide matrix

[0041] (1) 2.48 g of sodium thiosulfate and 11.54 g of cadmium sulfate powder were placed in beakers respectively, and 20 mL of water and 30 mL of water were added respectively to dissolve them by sonication for half an hour. The mixture was stirred evenly with a glass rod. Then the sodium thiosulfate solution was slowly added to the cadmium sulfate solution and stirred with a glass rod to mix them thoroughly to obtain the precursor solution. The concentration of sodium thiosulfate in the precursor solution was 0.2 mol / L and the concentration of cadmium sulfate was 0.9 mol / L.

[0042] (2) Transfer the precursor solution to a 10 cm diameter petri dish, add a 5 cm long cylindrical magnetic stir bar to the petri dish, and place two 8 W UV lamps parallel above the petri dish (vertically 4.5 cm apart) to make the light intensity above the liquid surface 0.277 mw / cm². 2 Then, under magnetic stirring at 350 r / min, the reaction was continuously irradiated for 24 h. After the reaction was stopped, the reaction product was washed by centrifugation, transferred to a petri dish of appropriate size, and dried in an oven for 12 h to obtain the photochemically synthesized cadmium sulfide matrix.

[0043] (1) 2.48 g of sodium thiosulfate and 11.54 g of cadmium sulfate powder were placed in beakers respectively, and 20 mL of water and 30 mL of water were added respectively to dissolve them by sonication for half an hour. The mixture was stirred evenly with a glass rod. Then the sodium thiosulfate solution was slowly added to the cadmium sulfate solution and stirred with a glass rod to mix them thoroughly to obtain the precursor solution. The concentration of sodium thiosulfate in the precursor solution was 0.2 mol / L and the concentration of cadmium sulfate was 0.9 mol / L.

[0044] (2) Transfer the precursor solution to a 10 cm diameter petri dish, add a 5 cm long cylindrical magnetic stir bar to the petri dish, and place two 8 W UV lamps parallel above the petri dish (vertically 4.5 cm apart) to make the light intensity above the liquid surface 0.277 mw / cm². 2 Then, under magnetic stirring at 350 r / min, the reaction was continuously irradiated for 24 h. After the reaction was stopped, the reaction product was washed by centrifugation, transferred to a petri dish of appropriate size, and dried in an oven for 12 h to obtain the photochemically synthesized cadmium sulfide matrix.

[0045] Example 5: Two-step photochemical synthesis of zinc sulfide and cadmium sulfide composite materials.

[0046] (1) 2.48 g of sodium thiosulfate and 12.94 g of zinc sulfate powder were placed in beakers respectively, and 20 mL and 30 mL of water were added respectively. After ultrasonic dissolution for half an hour, the mixture was stirred evenly with a glass rod. Then, the sodium thiosulfate solution was slowly added to the zinc sulfate solution, followed by 25 mg of cadmium sulfide matrix obtained in Example 3. The mixture was stirred with a glass rod to make it fully mixed to obtain the precursor solution. The concentration of cadmium sulfide in the precursor solution was 0.35 mmol / L, the concentration of sodium thiosulfate was 0.2 mol / L, and the concentration of zinc sulfate was 0.9 mol / L.

[0047] (2) Transfer the precursor solution to a 10 cm diameter petri dish, add a 5 cm long cylindrical magnetic stir bar to the petri dish, and place two 8 W UV lamps parallel above the petri dish (vertically 4.5 cm apart) to make the light intensity above the liquid surface 0.277 mw / cm². 2 Then, under magnetic stirring at 350 r / min, the reaction was continuously irradiated for 6 h. After the reaction was stopped, the reaction product was washed by centrifugation, transferred to a petri dish of appropriate size, and dried in an oven for 12 h to obtain the photochemically synthesized zinc sulfide and cadmium sulfide composite material.

[0048] Comparative Example 1: Hydrothermal Synthesis of Zinc Sulfide and Cadmium Sulfide Composite Materials Using Traditional Methods

[0049] 12.94 g of zinc sulfate and 11.54 g of cadmium sulfate were dissolved in two beakers respectively. 30 mL of water and 20 mL of water were added to each beaker, and the mixture was sonicated for half an hour. After stirring evenly with a glass rod, the zinc sulfate solution was added to the cadmium sulfate solution to make the concentrations of zinc sulfate and cadmium sulfate both 0.9 mol / L. Finally, 0.14 g of CTAB was added to the mixed solution. The resulting precursor solution was transferred into a polytetrafluoroethylene liner and reacted at 150 °C for 24 h. After the reaction, the system was cooled to room temperature. The product was removed, washed successively with anhydrous ethanol and distilled water, and centrifuged to obtain the final product. The product was transferred to a suitable-sized petri dish and dried in an oven for 12 h to obtain the hydrothermally synthesized zinc sulfide and cadmium sulfide composite material.

[0050] Experiment Example 1: Characterization and Performance Testing

[0051] (1) Morphological observation

[0052] Morphology images of the CdS matrix material and the zinc sulfide-cadmium sulfide composite material synthesized in two steps were obtained. Figure 1 The image shows the morphology of the zinc sulfide and cadmium sulfide composite material obtained in Example 5. The image exhibits a dense arrangement of granular and lamellar particles. Figure 2The images in Figures 1 through 4 show the morphology of the cadmium sulfide matrix materials obtained in Examples 1 through 4. It can be seen that only tightly packed particles exist in the images, and no plate-like morphology is observed. The comparison between the two shows that zinc sulfide and cadmium sulfide have been composited, and zinc sulfide and cadmium sulfide composite materials have been successfully prepared.

[0053] (2) Photocatalytic degradation performance test of zinc sulfide and cadmium sulfide composite materials

[0054] 30 mg of the zinc sulfide and cadmium sulfide composite material obtained in Example 5 was added to 50 mL of a solution containing 1.8 × 10⁻⁶ mg of zinc sulfide and cadmium sulfide. -5 In a 150 mL beaker containing g / L Rhodamine B organic dye, a 2.5 cm long magnetic stir bar was placed before dark adsorption, and the stirring speed was adjusted to 300 r / min. The degradation device was first placed in a dark environment for half an hour for dark adsorption. After the absorbance of the system stabilized, it was irradiated with a 50 W blue light for 1 hour. Samples were taken every ten minutes to measure the absorbance and a data point was recorded. A total of six measurements were taken. The light source was then turned off, and the degradation performance was obtained as follows: Figure 3 As shown, the degradation performance of zinc sulfide-cadmium sulfide composite materials is significantly improved compared to monomeric cadmium sulfide.

[0055] (3) Response test of zinc sulfide and cadmium sulfide photocatalyst dosage

[0056] A concentration gradient was set for the zinc sulfide and cadmium sulfide composite photocatalyst obtained in Example 5, with dosages of 30 mg, 35 mg, and 40 mg, respectively. Their effects on 50 mL of a 1.8 × 10⁻⁶ m³ photocatalyst were tested sequentially. -5 The degradation performance of rhodamine B organic dye at g / L was obtained, and the performance was as follows: Figure 4 As shown, with increasing catalyst dosage, there is an optimal value for photocatalytic degradation performance after one hour of degradation, at which the catalyst concentration is 35 mg / 50 mL and the degradation rate reaches 98.16%.

[0057] (4) Repeatability test of zinc sulfide and cadmium sulfide photocatalysts

[0058] The photocatalytic degradation effect of the zinc sulfide and cadmium sulfide composite materials obtained in Example 5 on Rhodamine B organic dye was continuously tested at a concentration of 35 mg / 50 mL. The degradation performance was as follows: Figure 5 As shown, this catalyst exhibits good reproducibility for Rhodamine B. Figure 5 (Left)). This data is then processed as follows: Figure 5 The linear fit shown on the right indicates a good linear relationship.

[0059] (5) Comparison of photocatalytic performance of composite materials synthesized by traditional hydrothermal method and two-step photochemical method

[0060] 35 mg of the zinc sulfide and cadmium sulfide composite materials obtained in Examples 5 and 6 were added to 50 mL of a solution containing 1.8 × 10⁻⁶ mg of zinc sulfide and cadmium sulfide composite material. -5 In a 150 mL beaker containing g / L Rhodamine B organic dye, a 2.5 cm long magnetic stir bar was placed before dark adsorption, and the stirring speed was adjusted to 300 r / min. The degradation device was first placed in a dark environment for dark adsorption for half an hour. After the absorbance of the system stabilized, it was irradiated with a 50 W blue light for 1 hour. Samples were taken every ten minutes to measure the absorbance and a data point was recorded. A total of six measurements were taken. The light source was then turned off, and the degradation performance of the two zinc sulfide and cadmium sulfide composite materials was compared. Figure 6 As shown, compared with the traditional hydrothermal method, the zinc sulfide and cadmium sulfide composite materials synthesized by the two-step photochemical method have a more significant advantage in degradation performance.

[0061] In summary, this invention utilizes a two-step photochemical synthesis of a zinc sulfide-cadmium sulfide composite material. This composite material is then used as a photocatalyst for the photocatalytic degradation of Rhodamine B dye under blue light. The degradation performance is significantly improved compared to monomeric cadmium sulfide, exhibiting better repeatability and stability, thus enhancing the photocatalytic degradation performance of current sulfide catalysts. Furthermore, the method for preparing the zinc sulfide-cadmium sulfide composite material is easy to operate, low-cost, environmentally friendly, and the synthesis conditions are readily available, facilitating large-scale production and application.

[0062] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A two-step photochemical synthesis method for zinc sulfide and cadmium sulfide composite materials, characterized in that, Includes the following steps: S1. First, prepare a precursor solution containing both cadmium and sulfur sources. Then, treat the precursor solution with ultraviolet light under stirring to obtain a cadmium sulfide matrix. S2. First, prepare a mixed solution containing both zinc source and sulfur source, then add the cadmium sulfide matrix obtained in step S1 to make a precursor solution. Then, under stirring, treat the precursor solution with ultraviolet light again to obtain zinc sulfide and cadmium sulfide composite material. In the ultraviolet irradiation treatment of step S1 or S2, the light intensity on the surface of the precursor liquid is 0.25-0.30 mw / cm². 2 The processing time is 6-24 hours.

2. The method for two-step photochemical synthesis of zinc sulfide and cadmium sulfide composite materials according to claim 1, characterized in that, In step S1, the concentration of the cadmium source is 0.7-1.1 mol / L, and the concentration of the sulfur source is 0.1-0.3 mol / L.

3. The method for two-step photochemical synthesis of zinc sulfide and cadmium sulfide composite materials according to claim 1, characterized in that, In step S2, the concentration of the zinc source is 0.7-1.1 mol / L, the concentration of the sulfur source is 0.1-0.3 mol / L, and the concentration of cadmium sulfide is 0.3-0.5 mmol / L.

4. The method for two-step photochemical synthesis of zinc sulfide and cadmium sulfide composite materials according to claim 1, characterized in that, The cadmium source includes cadmium sulfate, the sulfur source includes sodium thiosulfate, and the zinc source includes zinc sulfate.

5. The method for two-step photochemical synthesis of zinc sulfide and cadmium sulfide composite materials according to claim 1, characterized in that, In step S1 or S2, the stirring speed is 300-500 r / min.

6. The zinc sulfide and cadmium sulfide composite material prepared by the method according to any one of claims 1-5.

7. The application of the zinc sulfide and cadmium sulfide composite material according to claim 6 in the photocatalytic degradation of organic dyes.

8. The application according to claim 7, characterized in that, The organic dyes include Rhodamine B.

9. A method for photocatalytic degradation of organic dyes, characterized in that, The zinc sulfide and cadmium sulfide composite material of claim 6 is added to a solution containing organic dyes, and then subjected to dark adsorption for more than half an hour in a dark environment, followed by photocatalytic degradation under blue light for no less than 1 hour.

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