Preparation method and application of polytriazine imide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material
By preparing a composite material of highly crystalline graphitic carbon nitride loaded with cadmium sulfide quantum dots, the optical performance of traditional materials in visible light photocatalysts was solved, significantly improving photocatalytic activity. This solved the problem of unresolved photocatalytic activity in existing technologies, achieving highly efficient visible light sterilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF METAL RESEARCH - CHINESE ACAD OF SCI
- Filing Date
- 2022-12-31
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional semiconductor materials have limitations in photocatalytic activity. For example, cadmium sulfide has a high photogenerated carrier recombination rate, and graphite carbon nitride has a low carrier migration rate due to its low crystallinity. In addition, polytriazine imide has insufficient light absorption capacity, which limits its application in visible light.
Highly crystalline graphitic carbon nitride was prepared by thermal polymerization and molten salt calcination, and cadmium sulfide quantum dots were loaded onto it. The composite was carried out by solvothermal method to improve the efficiency of photogenerated charge separation and transfer, and expand the light absorption range to the visible light region.
It significantly improves photocatalytic sterilization capability, increases the light absorption cutoff edge from 400 nm to 520 nm, and improves the separation and transfer efficiency of photogenerated carriers, achieving highly efficient visible light sterilization performance.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of organic polymer functional materials technology, specifically to a method for preparing and applying a highly efficient bactericidal polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material. Background Technology
[0002] With rapid urbanization, industrialization, and population growth, water pollution has become increasingly serious. Traditional disinfection methods such as chlorination, Fenton chromatography, and biodegradation are either prone to causing secondary pollution, have stringent reaction conditions and high energy consumption, or have slow reaction rates. Photocatalysis, which emerged in the 1970s, is a highly efficient and safe disinfection method due to its advantages such as using sunlight as a direct energy source and being non-toxic and not causing drug resistance. The basic principle of photocatalysis is that semiconductor materials absorb light energy, causing their electrons to gain energy and transition, forming free electrons and holes. These free electrons and holes can react with oxygen-containing substances such as oxygen and water to form highly oxidizing oxygen-active species, which can effectively inactivate pathogenic microorganisms.
[0003] Traditional semiconductor materials all have their defects, which limit their photocatalytic activity. For example, cadmium sulfide, a common inorganic semiconductor material, is usually synthesized by precipitation, resulting in materials with large and uneven particle size distribution (Tao Haizheng, Jing Chengbin, Zhao Xiujian, et al. Preparation method of CdS nanoparticles[J]. Materials Reports, 2003, 17(3):4.). Its photocatalytic activity is limited by the high bulk photogenerated carrier recombination rate. On the other hand, graphitic carbon nitride, a common organic polymer semiconductor material, is mostly synthesized by directly calcining nitrogen-rich materials, forming an amorphous material (Wang X, Maeda K, Thomas A, et al. A metal-free polymeric photocatalyst for hydrogen production from waterunder visible light[J]. Nature Materials.). Therefore, its photocatalytic activity is low due to the low carrier migration rate caused by low crystallinity and the high recombination rate.
[0004] Currently, there are reports in the literature of the preparation of highly crystalline graphitic carbon nitride (polytriazine imide crystal form) using a molten salt-assisted method. Photoelectrochemical experiments and fluorescence spectroscopy results show that it has a significant improvement in carrier separation and migration compared to amorphous graphitic carbon nitride. However, a new problem has arisen: the reported polytriazine imide has weak light absorption capacity, with an absorption cutoff edge of 400 nm or below, no visible light response, and low utilization of sunlight. This is a very significant drawback that restricts its large-scale industrial application. Summary of the Invention
[0005] The purpose of this invention is to address the aforementioned shortcomings of existing technologies by providing a method for preparing and applying a highly efficient bactericidal polytriazineimide / cadmium sulfide quantum dot photocatalytic composite material. Graphitic carbon nitride is obtained through thermal polymerization, followed by a secondary calcination in a molten salt environment to prepare polytriazineimide, thereby improving its crystallinity and photogenerated charge separation and transfer efficiency. Finally, cadmium sulfide quantum dots are loaded onto the polytriazineimide using a solvothermal method, thus improving its light absorption performance and significantly enhancing its photocatalytic bactericidal ability.
[0006] To achieve the above objectives, the present invention employs the following technical solution:
[0007] A method for preparing a highly efficient bactericidal polytriazineimide / cadmium sulfide quantum dot photocatalytic composite material, the specific steps of which are as follows:
[0008] 1) Weigh 5-10 grams of nitrogen-rich material and place it in a crucible. Heat it to 500-600℃ in a muffle furnace at a heating rate of 2-5℃ / min and hold it at that temperature for 2-4 hours. After cooling, grind it to obtain graphitic carbon nitride powder.
[0009] 2) Weigh 200-500 mg of graphite carbon nitride, 1-4 g of potassium chloride and 1-4 g of lithium chloride, and grind for 3-10 minutes to obtain a uniform mixture;
[0010] 3) Transfer the mixture described in step 2) to a crucible or quartz tube, heat it to 500-600°C in a tube furnace at a heating rate of 2-5°C / min, and hold it at that temperature for 12-24 hours. The tube furnace gas flow is 50-200 ml / min of nitrogen. After cooling, wash, dry and grind to obtain polytriazine imide powder.
[0011] 4) Weigh 100-200 mg of polytriazine imide powder, 1-2 mmol of cadmium salt and sulfide, and add 60-80 mL of anhydrous ethanol. Stir at room temperature for 1-2 hours.
[0012] 5) Transfer the mixture described in step 4) to a hydrothermal reactor, heat it to 150-180°C in an oven and keep it at that temperature for 1-3 hours. After cooling, washing, drying and grinding, cadmium sulfide quantum dot / polytriazine imide powder is obtained.
[0013] The nitrogen-rich substances in step 1) above can be urea, melamine, dicyandiamine, ammonia nitrile, and thiourea, etc.
[0014] In step 4) above, the cadmium salt can be cadmium chloride or cadmium acetate, and the sulfide can be sodium sulfide or potassium sulfide.
[0015] In step 3) above, the crucible is an alumina crucible with a lid, and the quartz tube needs to be vacuum sealed.
[0016] The grinding process in steps 1), 2), 3), and 5) above is completed in an agate mortar, with a grinding speed of 60 revolutions per minute and a grinding time of 3-10 minutes.
[0017] In steps 3) and 5) above, the solvent used in the washing process is deionized water, the material is separated from the water by centrifugation, the centrifugation speed is 7000-9000 rpm, and the number of washing cycles is 3-5.
[0018] The stirring method in step 4) above is magnetic stirring, with a speed of 500-800 rpm.
[0019] The drying process in steps 3) and 5) above is carried out in a vacuum drying oven at a temperature of 50-80℃ for 12-15 hours.
[0020] The design mechanism of this invention is as follows:
[0021] This invention provides a highly efficient bactericidal polytriazineimide / cadmium sulfide quantum dot photocatalytic composite material and its preparation method. The process mainly includes three steps. The first step is the preliminary polymerization of nitrogen-rich substances. During this process, they gradually deaminate (as well as carbon dioxide, sulfur dioxide, etc.) and undergo a polymerization reaction, forming low-polymerized graphitic carbon nitride with a basic structure of tri-triazine rings at temperatures above 500°C. Then, the low-polymerized graphitic carbon nitride is subjected to secondary calcination in molten potassium chloride and lithium chloride. In this stage, the residual terminal amino groups are gradually removed, the long chains of low-polymerized carbon nitride polymerize, and the tri-triazine rings open to form highly crystalline graphitic carbon nitride (polytriazineimide) composed of triazine rings. The third step involves solvothermal treatment of the polytriazineimide with cadmium salts and sulfides in ethanol, loading cadmium sulfide quantum dots onto the surface of the polytriazineimide.
[0022] Compared with existing technologies, the advantages of this invention are:
[0023] 1) The technical route used in this invention is simple, the raw materials are cheap and abundant, and it is easy to prepare on a large scale.
[0024] 2) This invention uses calcined graphite carbon nitride as a precursor for the preparation of polytriazine imide, instead of directly using nitrogen-rich raw materials. The process is clearer, the crystallization effect is more thorough, and the restrictions on reaction conditions are smaller, eliminating the need for extensive experimental processes.
[0025] 3) This invention significantly improves the crystallinity of graphitic carbon nitride materials through molten salt heat treatment, and at the same time greatly enhances the separation and transfer performance of photogenerated carriers.
[0026] 4) The cadmium sulfide quantum dots introduced in this invention have a size of less than 20 nanometers. Compared with bulk cadmium sulfide materials in the literature, their photoelectric properties are significantly improved, and the preparation method is relatively simple, making them more suitable for industrial applications.
[0027] 5) This invention composites cadmium sulfide quantum dots onto polytriazineimide using a solvothermal method, which not only accelerates the separation and transfer of photogenerated carriers, but also increases its light absorption cutoff edge from less than 400 nanometers to 520 nanometers, significantly improving its visible light absorption capacity, thus exhibiting excellent bactericidal properties. Attached Figure Description
[0028] Figure 1 X-ray diffraction pattern of polytriazine imide;
[0029] Figure 2 X-ray diffraction pattern of polytriazineimide / cadmium sulfide quantum dot composite material;
[0030] Figure 3 This is a scanning electron microscope image of polytriazine imide;
[0031] Figure 4 Scanning electron microscope image of polytriazineimide / cadmium sulfide quantum dot composite material;
[0032] Figure 5 Energy dispersive spectroscopy (EDS) analysis of polytriazineimide / cadmium sulfide quantum dot composite material;
[0033] Figure 6 Comparison of light absorption between polytriazineimide and polytriazineimide / cadmium sulfide quantum dot composite material;
[0034] Figure 7 Comparison of photocurrents for polytriazineimide, cadmium sulfide, and polytriazineimide / cadmium sulfide quantum dot composites;
[0035] Figure 8 Comparison of the photocatalytic killing effects of polytriazineimide, cadmium sulfide, and polytriazineimide / cadmium sulfide quantum dot composites on Escherichia coli. Detailed Implementation
[0036] The technical solution of the present invention will be described more comprehensively and in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.
[0037] Example 1
[0038] This embodiment provides a method for preparing low-polymer graphitic carbon nitride, the specific steps of which are as follows:
[0039] 1) Weigh 10 grams of urea into a 100 ml covered alumina crucible, heat it to 500°C in a muffle furnace at a rate of 5°C / min and hold for 2 hours, then cool it to room temperature.
[0040] 2) Grind the light yellow material obtained after cooling in step 1) in an agate mortar for 3 minutes to obtain light yellow low-polymer graphitic carbon nitride powder.
[0041] Example 2
[0042] This embodiment provides a method for preparing low-polymer graphitic carbon nitride, the specific steps of which are as follows:
[0043] 1) Weigh 5 grams of melamine and place it in a 50 ml covered alumina crucible. Heat it in a muffle furnace to 550°C at a rate of 2.3°C / min and hold for 4 hours. Then cool it to room temperature.
[0044] 2) Grind the yellow block obtained after cooling in step 1) in an agate mortar for 5 minutes to obtain yellow low-polymer graphitic carbon nitride powder.
[0045] Example 3
[0046] This embodiment provides a method for preparing polytriazine imide, the specific steps of which are as follows:
[0047] 1) Weigh 200 mg of the pale yellow powder obtained in Example 1, and then weigh 3.72 g of potassium chloride and 3.24 g of lithium chloride respectively. Grind them carefully in an agate mortar for 10 minutes to obtain a uniform pale yellow mixture.
[0048] 2) Place the pale yellow mixture obtained in step 1) into a 22 mL covered alumina crucible, place it in a tube furnace and purge it with nitrogen gas at a rate of 100 mL / min, heat it to 550 °C at a rate of 30 °C / min and hold it at that temperature for 12 hours, then cool it down according to the program.
[0049] 3) Wash the cooled material in hot deionized water and centrifuge three times at 9000 rpm. Dry it in a vacuum drying oven at 60°C for 12 hours. Finally, grind it carefully in an agate mortar for 5 minutes to obtain polytriazine imide powder. Figure 1 As shown, polytriazine imide exhibits multiple sharp diffraction peaks, consistent with literature results, indicating a high degree of crystallinity in the material. Figure 3 As shown, the morphology of polytriazine imide is a hexagonal prism with a size of 200 nanometers, which also indicates that its crystal growth is good.
[0050] Example 4
[0051] This embodiment provides a method for preparing polytriazine imide, the specific steps of which are as follows:
[0052] 1) Weigh 1 gram of the yellow powder obtained in Example 2, then weigh 5.5 grams of potassium chloride and 4.5 grams of lithium chloride, and grind them carefully in an agate mortar for 10 minutes to obtain a uniform yellow mixture.
[0053] 2) Place the pale yellow mixture obtained in step 1) into a 25 ml quartz tube, and seal the tube under vacuum. Then place the quartz tube in a muffle furnace, heat it to 550°C at a rate of 1°C / min and hold it at that temperature for 24 hours, followed by programmed cooling.
[0054] 3) Wash the cooled material in hot deionized water and centrifuge it three times at 8500 rpm. Dry it in a vacuum drying oven at 60°C for 12 hours. Finally, grind it carefully in an agate mortar for 5 minutes to obtain polytriazine imide powder.
[0055] Example 5
[0056] This embodiment provides a method for preparing ultrafine cadmium sulfide materials, the specific steps of which are as follows:
[0057] 1) Weigh 0.48 g of sodium sulfide and 0.456 g of cadmium chloride and put them into a 150 ml beaker;
[0058] 2) Measure 80 ml of anhydrous ethanol and add it to the beaker described in step 1), then stir magnetically at 700 rpm for 1 hour.
[0059] 3) Transfer the liquid mixture obtained in step 2) to a 100 mL hydrothermal reactor and place it in an oven for solvothermal reaction at 180 °C for two hours;
[0060] 4) Wash the cooled material with deionized water and anhydrous ethanol respectively, centrifuge three times at 8000 rpm, dry it in a vacuum drying oven at 50°C for 15 hours, and finally grind it carefully in an agate mortar for 5 minutes to obtain ultrafine cadmium sulfide material.
[0061] Example 6
[0062] This embodiment provides a method for preparing polytriazineimide / cadmium sulfide quantum dot composite photocatalytic materials, the specific steps of which are as follows:
[0063] 1) Weigh 100 mg of the polytriazine imide powder from Example 2 or 4, then weigh 0.24 g of sodium sulfide and 0.228 g of cadmium chloride, and put them into a 150 mL beaker;
[0064] 2) Measure 80 ml of anhydrous ethanol and add it to the beaker described in step 1), then stir magnetically at 700 rpm for 1 hour.
[0065] 3) Transfer the liquid mixture obtained in step 2) to a 100 mL hydrothermal reactor and place it in an oven for solvothermal reaction at 180 °C for two hours;
[0066] 4) The cooled material was washed with deionized water and anhydrous ethanol respectively, centrifuged three times at 8000 rpm, dried in a vacuum drying oven at 50°C for 15 hours, and finally carefully ground in an agate mortar for 5 minutes to obtain the polytriazineimide / cadmium sulfide quantum dot composite photocatalytic material. Figure 2 As shown, the XRD pattern of this composite material simultaneously contains diffraction peaks for both polytriazine imide and cadmium sulfide, indicating that the composite material was successfully synthesized. Figure 4 As shown, many very fine particles are distributed on the hexagonal prism of polytriazineimide, combined with... Figure 5 The presence of cadmium and sulfur in the sample confirms that cadmium sulfide quantum dots were successfully loaded onto polytriazine imide.
[0067] Example 7
[0068] This embodiment utilizes the polytriazineimide, cadmium sulfide, and polytriazineimide / cadmium sulfide quantum dot composite photocatalytic materials prepared in Examples 3, 5, and 6 to conduct light absorption tests, photocurrent tests, and simulated sunlight-induced E. coli killing tests. The specific steps are as follows:
[0069] 1) Take 20 mg of photocatalytic material, press it into a sheet using a diffuse reflectance sample stage, test its diffuse reflectance performance in a UV-Vis spectrometer, and then convert it into light absorption performance using the KM equation;
[0070] 2) Take 10 mg of photocatalytic material and dissolve it in 80 μL of PVDF / NMP solution. Grind the solution in an agate mortar for 5 minutes to obtain a uniform suspension. Take 12 mg of the suspension and coat it onto an FTO glass plate. Dry the plate in an oven at 80°C for 4 hours to obtain the working electrode. Place the working electrode, platinum wire counter electrode, and saturated calomel reference electrode into a three-electrode system in 0.2 mol / L NaSO4 electrolyte and apply simulated sunlight to perform photocurrent testing.
[0071] 3) Take 10 mg of photocatalytic material and dissolve it in 1 mL of phosphate buffer. Sonicate for 20 minutes to ensure thorough dispersion. Then, mix the material suspension with 1 mL of 3×10⁻⁶ phosphate buffer. 8 CFU / mL E. coli culture and 8 mL phosphate buffer were placed in a disposable plastic petri dish. The system was then incubated at a light intensity of 55 mW / cm². 2 A photocatalytic sterilization experiment was conducted under simulated sunlight. At a specific time, 100 μL of liquid was taken and diluted 0-4 times (each dilution was 10 times). 100 μL of the diluted liquid was then evenly spread on the surface of an agar medium and incubated at 37°C for 24 hours before counting.
[0072] 4) Figure 6The image shows a comparison of the light absorption of polytriazineimide and polytriazineimide / cadmium sulfide quantum dot composites. The light absorption cutoff edge of the composite material reaches 520 nm, and its visible light absorption capacity far exceeds that of polytriazineimide. Figure 7 The results show the photocurrent test results of polytriazineimide, cadmium sulfide, and polytriazineimide / cadmium sulfide quantum dot composites. The composites show a significant improvement compared to the two single-phase materials, indicating that the separation and transfer efficiency of photogenerated carriers is significantly improved. Figure 8 The figure shows the survival rate of three materials in photocatalytic killing of E. coli under simulated sunlight. The composite material can completely inactivate seven orders of magnitude of E. coli within 60 minutes, and its photocatalytic bactericidal performance far exceeds that of the other two.
[0073] It should be understood that after reading the above description and explanation, those skilled in the art can modify and alter the specific technical solutions of this invention. Therefore, this invention is not limited to the specific embodiments described and explained above, and any modifications and alterations made to this invention should also be within the scope of protection of the claims of this invention. In addition, some specific technical terms are used in the above description, but these technical terms are only for the purpose of assisting in the explanation of this invention and do not constitute any limitation on this invention.
Claims
1. A method for preparing a polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material, characterized in that: The method includes the following steps: (1) Weigh 100-200 mg of polytriazine imide, 1-2 mmol of cadmium salt and sulfide, and add 60-80 mL of anhydrous ethanol. Stir at room temperature for 1-2 hours to obtain a mixture. (2) Transfer the mixture obtained in step (1) to a hydrothermal reactor, heat it to 150-180°C in an oven, and keep it at that temperature for 1-3 hours; (3) The mixture after treatment (2) is washed, dried and ground in sequence to obtain the obtained polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material.
2. The method for preparing the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material according to claim 1, characterized in that: In step (1), the polytriazine imide is in powder form, and its preparation process includes the following steps (a)-(c): (a) Weigh 5-10 grams of nitrogen-rich material and place it in a crucible. Heat it in a muffle furnace to 500-600°C and keep it at that temperature for 2-4 hours. After cooling, grind it to obtain graphite carbon nitride powder. (b) Weigh 200-500 mg of graphite carbon nitride prepared in step (1), 1-4 g of potassium chloride and 1-4 g of lithium chloride, and grind for 3-10 minutes to obtain a uniform mixture; (c) Transfer the mixture described in step (b) to a crucible or quartz tube, heat it to 500-600°C in a tube furnace, and keep it at that temperature for 12-24 hours. After cooling, wash, dry, and grind to obtain polytriazine imide powder.
3. The method for preparing the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material according to claim 2, characterized in that: In step (a), the crucible is an alumina crucible with a lid; in step (c), the quartz tube needs to be vacuum sealed.
4. The method for preparing the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material according to claim 2, characterized in that: In step (a), the heating rate of the muffle furnace is 3-5℃ / min; in step (c), the heating rate of the tube furnace is 5-30℃ / min, and nitrogen gas with a flow rate of 50-200 ml / min is introduced into the tube furnace.
5. The method for preparing the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material according to claim 2, characterized in that: In step (a), the nitrogen-rich substance is any one of urea, thiourea, melamine, dicyandiamine, or ammonia nitrile.
6. The method for preparing the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material according to claim 1, characterized in that: In step (1), the cadmium salt is cadmium chloride or cadmium acetate; the sulfide is sodium sulfide or potassium sulfide.
7. The method for preparing the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material according to claim 1, characterized in that: In step (1), the stirring method is magnetic stirring with a speed of 500-800 rpm; the drying is carried out in a vacuum drying oven at a temperature of 50-80℃ for 12-15 hours.
8. The method for preparing the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material according to claim 1 or 2, characterized in that: The grinding is done using an agate mortar and pestle at a speed of 60 revolutions per minute; the detergent is deionized water, and the material is separated from the water by centrifugation at a speed of 7000-9000 revolutions per minute, with 3-5 washing cycles.
9. An application of the polytriazineimide / cadmium sulfide quantum dot organic / inorganic photocatalytic composite material prepared by the method of claim 1, characterized in that: This composite material is used for photocatalytic sterilization.