Monatomic silver modified graphite phase carbon nitride solution catalyst as well as preparation method and application thereof
The treatment of g-C3N4 by alcohol thermal method and photoreduction of single atomic silver was solved, and the problems of cumbersome preparation process of Ag/g-C3N4 catalyst and waste of silver resources were achieved, and efficient photocatalytic degradation of organic dyes and bactericidal effects were achieved, while reducing the preparation cost and environmental impact.
Patent Information
- Application Number
- CN202410466823.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-17
- Publication Date
- 2025-07-18
AI Technical Summary
The preparation process of existing Ag/g-C3N4 catalysts is cumbersome, silver resources are wasteful, and the discharge of silver ions in the supernatant is burdened to the environment, the utilization rate of silver ions is low, and the photocatalytic efficiency is not high.
G-C3N4 is treated by alcohol thermal method to prepare oxygen-doped g-C3N4, and single atomic silver is deposited on it by photoreduction. The solution after photodeposition is directly used as a catalytic system to avoid centrifugation and drying steps, and residual silver ions are used as electron sacrificial agent.
The dispersion and hydrophilicity of the catalyst are improved, the photocatalytic efficiency is enhanced, the preparation cost is reduced, and the impact of silver ions on the environment is reduced, which significantly improves the photocatalytic degradation of organic dyes and bactericidal effects.
Smart Images
Figure CN120325307A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of composite materials, and particularly to a single-atom silver modified graphitic carbon nitride solution catalyst, a preparation method thereof and an application thereof. Background Art
[0002] The water pollution problem brought about by the rapid development of industrialization has become increasingly prominent. It is reported that more than 70 billion tons of printing and dyeing wastewater are generated globally every year. Since these synthetic dyes have biological toxicity and chemical stability and can exist in water for a long time, they pose a serious threat to the ecosystem and human health. In addition, more than 480,000 deaths are caused by drinking water contaminated by pathogenic microorganisms such as Escherichia coli every year. Therefore, it is crucial to develop an efficient and economical method for water pollution treatment.
[0003] At present, semiconductor photocatalysis technology is considered to be a very promising method due to its advantages of high efficiency, greenness, economy, etc. Among many semiconductors, graphitic carbon nitride (g-C3N4), as a two-dimensional non-metallic semiconductor, has good chemical stability, visible light response, simple preparation method, low cost and non-toxicity, and has received extensive attention in the fields of environmental photocatalysis, energy photocatalysis, photocatalytic organic synthesis and photocatalytic health. However, when g-C3N4 is used for photocatalysis, there are deficiencies such as low visible light utilization rate, high recombination rate of photo-generated electrons and holes, and easy aggregation between layers resulting in few active sites, which cannot meet the actual application requirements. So far, a series of g-C3N4 modification strategies have been developed to improve photocatalytic activity, such as constructing heterojunctions, morphology regulation, element doping, etc.
[0004] Among them, silver doping to construct an Ag / g-C3N4 heterojunction is an effective strategy to improve photocatalytic activity. It can make full use of the local surface plasmon resonance effect (LSPR) of silver to enhance the utilization efficiency of visible light. Existing methods for preparing Ag / g-C3N4 heterojunctions include sodium borohydride reduction, mixing and sintering of silver ions and g-C3N4 precursors, photoreduction deposition method, etc. Among them, the photoreduction deposition method directly uses photo-generated electrons generated by visible light to reduce silver ions, thereby depositing on the surface of g-C3N4 to obtain an Ag / g-C3N4 heterojunction. It is a green, simple and low-cost method, and has obvious advantages in large-scale production. However, the main steps of the Ag / g-C3N4 catalyst prepared by the photoreduction deposition method reported at present include: 1) mixing silver ions and g-C3N4; 2) photoreduction deposition; 3) centrifuging / filtering to remove the supernatant; 4) drying to obtain Ag / g-C3N4 dry powder. The process of obtaining Ag / g-C3N4 by this traditional process is relatively cumbersome. There are a large number of undeposited silver ions and silver nanoparticles in the supernatant. Directly discarding them will cause waste of silver resources and bring a burden to the ecological environment.
[0005] Therefore, there is an urgent need for a method for preparing an Ag / g-C3N4 composite catalyst that can improve the utilization rate of silver ions. Summary of the invention
[0006] The invention provides a single-atom silver-modified graphite-phase carbon nitride solution catalyst and a preparation method and application thereof.
[0007] In order to solve the above technical problems, the present invention provides a method for preparing a single-atom silver-modified graphite phase carbon nitride solution catalyst, comprising the following steps: step S1, preparing g-C3N4 by thermal polymerization using a precursor; step S2, ultrasonically dispersing the g-C3N4 in anhydrous ethanol, and then performing alcohol heat treatment in a reactor to obtain oxygen-doped g-C3N4; step S3, adding the oxygen-doped g-C3N4 into water to form a suspension and ultrasonicating it, then adding silver nitrate and stirring it sufficiently, and then performing photoreduction deposition to obtain a single-atom silver-modified graphite phase carbon nitride solution catalyst.
[0008] Furthermore, in step S1: the precursor includes any one or more combinations of urea, melamine, and thiourea.
[0009] Furthermore, in step S1: the temperature of the thermal polymerization method is 450-600°C.
[0010] Furthermore, in step S2: the ultrasonic dispersion time is 30 to 60 minutes.
[0011] Furthermore, in step S2: the temperature of the alcohol heat treatment is 180-200°C.
[0012] Furthermore, in step S3: the system of oxygen-doped g-C3N4 required for the photoreduction deposition is 100mL~10L, and the concentration is 0.1~0.5g / L.
[0013] Furthermore, in step S3: the final concentration of the silver nitrate is 10-60 mg / L.
[0014] Furthermore, in step S3: the reaction time of the photoreduction deposition is 10 to 60 minutes.
[0015] In another aspect, the present invention further provides a single-atom silver-modified graphite-phase carbon nitride solution catalyst, which is prepared by the preparation method of the single-atom silver-modified graphite-phase carbon nitride solution catalyst as described above.
[0016] In a third aspect, the present invention also provides a single-atom silver-modified graphite-phase carbon nitride solution catalyst prepared by the method described above or the use of the single-atom silver-modified graphite-phase carbon nitride solution catalyst described above in the degradation of organic dyes and sterilization in water.
[0017] The beneficial effects of the present invention are as follows. The single-atom silver-modified graphitic carbon nitride solution catalyst of the present invention and its preparation method and application can obtain more dispersed and hydrophilic oxygen-doped g-C3N4 by treating g-C3N4 through the solvothermal method. Therefore, it has higher catalytic efficiency. At the same time, different from the prior art, the present invention directly uses the solution after photodeposition as the catalytic system. Firstly, the residual silver ions in the solution are used as electron sacrificial agents, further significantly improving the photocatalytic efficiency. Secondly, the preparation of the solution catalyst does not require steps such as centrifugation / filtration and drying, greatly reducing the preparation cost of the catalyst. Thirdly, it can effectively alleviate the impact caused by the discharge of silver ions in the supernatant into the environment.
[0018] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structures specifically pointed out in the specification and the drawings.
[0019] To make the above objectives, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given in conjunction with the accompanying drawings and are described in detail as follows. Description of the Drawings
[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0021] Figure 1 Shows the XRD diagrams related to some embodiments;
[0022] Figure 2 Shows the TEM, AC-HADDF-STEM, and elemental mapping diagrams related to some embodiments;
[0023] Figure 3 Shows the comparative diagram of the photocatalytic degradation performance of Rhodamine B related to some embodiments;
[0024] Figure 4 Shows the comparative diagram of the photocatalytic antibacterial effect related to some embodiments. Detailed Description of the Embodiments
[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0026] At least one embodiment provides a method for preparing a single-atom silver-modified graphitic carbon nitride solution catalyst, including the following steps: Step S1, preparing g-C3N4 by a thermal polymerization method using a precursor; Step S2, ultrasonically dispersing g-C3N4 in absolute ethanol, and then performing alcohol heat treatment in a reaction kettle to obtain oxygen-doped g-C3N4; Step S3, adding the oxygen-doped g-C3N4 into water to form a suspension and ultrasonically treating it, then adding silver nitrate and stirring thoroughly, and subsequently performing photoreduction deposition to obtain a single-atom silver-modified graphitic carbon nitride solution catalyst.
[0027] Among them, in Step S1: The precursor includes any one or a combination of urea, melamine, and thiourea; the temperature of the thermal polymerization method is 450 - 600 °C.
[0028] Among them, in Step S2: The time for ultrasonic dispersion is 30 - 60 min; the temperature for alcohol heat treatment is 180 - 200 °C.
[0029] Among them, in Step S3: The system of oxygen-doped g-C3N4 required for photoreduction deposition is 100 mL - 10 L, and the concentration is 0.1 - 0.5 g / L; the final concentration of silver nitrate is 10 - 60 mg / L; the reaction time for photoreduction deposition is 10 - 60 min.
[0030] On the other hand, the present invention also provides a single-atom silver-modified graphitic carbon nitride solution catalyst prepared by the method for preparing a single-atom silver-modified graphitic carbon nitride solution catalyst as described above.
[0031] In the third aspect, the present invention also provides an application of a single-atom silver-modified graphitic carbon nitride solution catalyst prepared by the method as described above or a single-atom silver-modified graphitic carbon nitride solution catalyst as described above in degrading organic dyes and sterilizing in water.
[0032] Specifically, the abbreviated names of each substance in this embodiment are as follows: g-C3N4 (BCN), oxygen-doped g-C3N4 (OCN), single-atom silver-modified graphitic carbon nitride solution catalyst (S-Ag-OCN).
[0033] Example 1
[0034] Put 30 g of urea into a crucible, cover the lid, and heat it in a muffle furnace at a heating rate of 20 °C / min to 550 °C for calcination for 4 h. After natural cooling, blocky g-C3N4 (BCN) is obtained;
[0035] Add 600 mg of BCN in Example 1 to 150 mL of absolute ethanol and ultrasonically treat it for 30 min to obtain a g-C3N4 suspension. Then pour the suspension into a stainless-steel autoclave and place it in an oven at 180 °C for 12 hours. Wash the obtained oxygen-doped g-C3N4 (OCN) three times with ultrapure water and dry it in an oven at 60 °C for 8 hours;
[0036] Take 30 mg of the above-prepared oxygen-doped g-C3N4 and add it to 100 mL of ultrapure water. Place it in an ultrasonic instrument and ultrasonically treat it for 10 min. After taking it out, add 1 mL of 2 mg / mL silver nitrate solution, stir well for 5 min, and then irradiate it with a 500 W xenon lamp (plus a 420 nm filter) for 30 min. Obtain S-Ag-OCN-2 solution.
[0037] Example 2
[0038] Take 30 mg of OCN prepared in Example 1 and add it to 100 mL of ultrapure water. Place it in an ultrasonic instrument and ultrasonically treat it for 10 min. After taking it out, add 0.5 mL of 2 mg / mL silver nitrate solution, stir well for 5 min, and then irradiate it with a 500 W xenon lamp (plus a 420 nm filter) for 30 min. Obtain S-Ag-OCN-1 solution.
[0039] Example 3
[0040] Take 30 mg of OCN prepared in Example 1 and add it to 100 mL of ultrapure water. Place it in an ultrasonic instrument and ultrasonically treat it for 10 min. After taking it out, add 1.5 mL of 2 mg / mL silver nitrate solution, stir well for 5 min, and then irradiate it with a 500 W xenon lamp (plus a 420 nm filter) for 30 min. Obtain S-Ag-OCN-3 solution.
[0041] Comparative Example 1
[0042] Filter the OCN prepared in Example 1 on a 0.22 μm filter membrane, and then dry it in an oven at 60 °C for 8 hours to obtain a powder catalyst OCN.
[0043] Comparative Example 2
[0044] Filter the S-Ag-OCN-2 solution prepared in Example 1 on a 0.22 μm filter membrane, and then dry it in an oven at 60 °C for 8 hours to obtain a powder catalyst Ag-OCN-2.
[0045] Application Example 1
[0046] 100 mL of the S-Ag-OCN-2 solution prepared in Example 1 was added with rhodamine B to make its concentration 10 mg / L, and a magnetic stir bar was added. The mixture was placed under a 500 W xenon lamp (with a 420 nm filter). First, the stirring button was turned on, and the adsorption-desorption equilibrium was reached in the dark reaction. Then the lamp was turned on for degradation.
[0047] Application Example 2
[0048] The difference from Application Example 1 is that the S-Ag-OCN-2 catalytic material prepared in Example 1 was replaced with the S-Ag-OCN-1 catalytic material of Example 2, and the rest is the same as Application Example 1.
[0049] Application Example 3
[0050] The difference from Application Example 1 is that the S-Ag-OCN-2 catalytic material prepared in Example 1 was replaced with the S-Ag-OCN-3 prepared in Example 3, and the rest is the same as Application Example 1.
[0051] Application Example 4
[0052] The difference from Application Example 1 is that the S-Ag-OCN-2 catalytic material prepared in Example 1 was replaced with the OCN prepared in Comparative Example 1, and the rest is the same as Application Example 1.
[0053] Application Example 5
[0054] The difference from Application Example 1 is that the S-Ag-OCN-2 catalytic material prepared in Example 1 was replaced with the powder catalyst Ag-OCN-2 prepared in Comparative Example 2, and the rest is the same as Application Example 1.
[0055] Application Example 6
[0056] The difference from Application Example 1 is that the S-Ag-OCN-2 catalytic material prepared in Example 1 was replaced with BCN, and the rest is the same as Application Example 1.
[0057] Performance Test
[0058] (1) The phase analysis of BCN, OCN, S-Ag-OCN-2 prepared in Example 1 of the present invention, S-Ag-OCN-1 in Example 2, and S-Ag-OCN-3 in Example 3 was carried out by XRD, and the results are as Figure 1 shown.
[0059] From Figure 1It can be seen that the characterization results of XRD show that the interlayer crystallinity of BCN, OCN, Ag-OCN-1, Ag-OCN-2, and Ag-OCN-3 becomes worse in turn, and becomes worse with the increase of Ag loading, indicating that alcohol heat treatment can play an interlayer exfoliation effect and proves that Ag is intercalated into the interlayer of graphite phase carbon nitride; in addition, no characteristic peak of Ag is found in the XRD spectra of Ag-OCN-1, Ag-OCN-2, and Ag-OCN-3, which indirectly indicates that it may be a modification of single atomic silver.
[0060] (2) The morphology of BCN, OCN, and S-Ag-OCN-2 prepared in Example 1 of the present invention was characterized by TEM. The results are as follows Figure 2 As shown, ac are TEM images of BCN, OCN, and Ag-OCN-2, respectively; d is the AC-HADDF-STEM image of Ag-OCN-2; and e is the element mapping image of Ag-OCN-2, which are C, N, O, and Ag from the second left to the right.
[0061] Depend on Figure 2 It can be seen that the BCN layers aggregated and appeared blocky. After alcohol heat treatment, the OCN layers were gradually peeled off. After photoreduction deposition, S-Ag-OCN-2 was further peeled off, but no Ag nanoparticles were observed on the nanosheets. However, the AC-HADDF-STEM image clearly showed that single-atom Ag was uniformly modified on the nanosheets. The element mapping image showed that the four elements C, N, O, and Ag were uniformly distributed on Ag-OCN-2, which once again proved that single-atom Ag was successfully modified on the nanosheets.
[0062] (3) The degradation effect of different catalytic materials on rhodamine B was tested. The specific experimental process is as shown in Application Example 1, where the light source is a 500W xenon lamp (with a 420nm filter), the catalyst concentration is 0.3g / L. The concentration of rhodamine B is 10mg / L. 4mL of the sample is taken every 5 minutes and centrifuged for 10 minutes, and the concentration of rhodamine B in the solution is measured by a spectrophotometer.
[0063] The degradation results of Rhodamine B are as follows Figure 3As shown in the figure, it can be seen that the photocatalytic degradation performance of BCN is the worst. After alcohol heat treatment, the photocatalytic degradation performance of OCN becomes stronger. After further modification with single-atom silver, the photocatalytic performance of the Ag-OCN powder catalyst is further improved. When the S-Ag-OCN solution is used as the catalyst as a whole, its photocatalytic performance is significantly improved. The degradation rate of the S-Ag-OCN solution catalyst for rhodamine B in 15 minutes is about 100%. When the supernatant of the S-Ag-OCN solution is used alone for photocatalytic degradation, the results show that its degradation rate for rhodamine B is very slow, indicating that the free silver ions in the solution play a synergistic promoting role in the whole photocatalytic degradation process.
[0064] (4) The bactericidal effects of different catalytic materials on Escherichia coli were tested. The specific experimental process is as follows: The light source is a 500W xenon lamp (plus a 420nm filter), the catalyst concentration is 0.2g / L, and the initial concentration of Escherichia coli is 107 cfu / mL. 100 μL was sampled at a predetermined time interval and diluted 10 times with normal saline. 100 μL was taken and spread on the LB solid medium, and the counting statistics were carried out after 24 hours. The bactericidal effects of different catalysts on Escherichia coli within 30 minutes are as Figure 4 shown.
[0065] First of all, it can be seen that under the condition of no light, the S-Ag-OCN-2 solution has a certain bactericidal effect. The main reason is that the free silver ions in the solution have a certain bactericidal effect. When the light condition is given, the S-Ag-OCN-2 solution has a better bactericidal effect than BCN and other solution catalysts. The mortality rate of Escherichia coli is close to 100% within 20 minutes.
[0066] On the one hand, the free silver ions in the solution have a certain bactericidal effect. On the other hand, the silver ions act as an electron sacrificial agent, further improving the separation of photogenerated carriers, thereby improving the photocatalytic effect and generating a large amount of reactive oxygen free radicals to kill the bacteria in the water.
[0067] In summary, the single-atom silver-modified graphitic carbon nitride solution catalyst of the present invention and its preparation method and application can obtain more dispersed and more hydrophilic oxygen-doped g-C3N4 by treating g-C3N4 by the alcohol thermal method. Therefore, it has higher catalytic efficiency. At the same time, different from the prior art, the directly used solution after photodeposition is used as the catalytic system. Firstly, the residual silver ions in the solution are used as electron sacrificial agents, further significantly improving the photocatalytic efficiency. Secondly, the preparation of the solution catalyst does not require steps such as centrifugation / filtration and drying, greatly reducing the preparation cost of the catalyst. Thirdly, it can effectively alleviate the impact caused by the discharge of silver ions in the supernatant into the environment.
[0068] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0069] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0070] Based on the above inspiration from the ideal embodiments of the present invention, through the above description, relevant workers can completely make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. A preparation method of a single-atom silver modified graphite-phase carbon nitride solution catalyst, characterized in that, It includes the following steps: Step S1: Prepare g-C3N4 by thermal polymerization using a precursor. Step S2: Ultrasonically disperse g-C3N4 in absolute ethanol, and then perform alcohol heat treatment in a reaction kettle to obtain oxygen-doped g-C3N4. Step S3: Add the oxygen-doped g-C3N4 into water to form a suspension and ultrasonicate it. Then add silver nitrate and stir well. Subsequently, perform photoreduction deposition to obtain a single-atom silver-modified graphitic carbon nitride solution catalyst.
2. The preparation method according to claim 1, characterized in that, In step S1: The precursor includes any one or a combination of urea, melamine, and thiourea.
3. The preparation method according to claim 1, wherein In step S1: The temperature of the thermal polymerization method is 450 - 600 °C.
4. The preparation method according to claim 1, wherein, In step S2: The time for ultrasonic dispersion is 30 - 60 min.
5. The preparation method according to claim 1, characterized in that, In step S2: The temperature of the alcohol heat treatment is 180 - 200 °C.
6. The preparation method according to claim 1, characterized in that, In step S3: The system of the oxygen-doped g-C3N4 required for photoreduction deposition is 100 mL - 10 L, and the concentration is 0.1 - 0.5 g / L.
7. The preparation method according to claim 1, characterized in that, In step S3: The final concentration of silver nitrate is 10 - 60 mg / L.
8. The preparation method according to claim 1, wherein In step S3: The reaction time for photoreduction deposition is 10 - 60 min.
9. A single-atom silver-modified graphitic carbon nitride solution catalyst, characterized in that, It is prepared by the preparation method of the single-atom silver-modified graphitic carbon nitride solution catalyst according to any one of claims 1 - 8.
10. The application of the single-atom silver-modified graphitic carbon nitride solution catalyst prepared by the method according to any one of claims 1 - 8 or the single-atom silver-modified graphitic carbon nitride solution catalyst according to claim 9 in the degradation of organic dyes and sterilization in water.