Poly (heptazinyl imide) photocatalytic material, preparation method thereof and method for preparing H2O2 through photocatalysis
By using dicyandiamide and triaminopyrimidine to prepare highly crystalline poly(heptaazinimide) nanorod clusters, the problems of low efficiency and complex preparation of photocatalytic materials in the prior art have been solved, achieving efficient photocatalytic preparation of hydrogen peroxide and promoting industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2026-02-03
- Publication Date
- 2026-05-12
AI Technical Summary
Existing poly(heptamethrinimide) photocatalytic materials have low efficiency in preparing hydrogen peroxide, and the preparation methods are complex, making them difficult to apply industrially.
Highly crystalline poly(heptamethrinimide) nanorod clusters were prepared by multi-step calcination using dicyandiamide and triaminopyrimidine as raw materials. Triaminopyrimidine improved the crystallinity and photocatalytic activity of PHI.
The efficiency of photocatalytic preparation of hydrogen peroxide was improved, the carrier migration efficiency was significantly enhanced, and the reaction rate reached 4880 μmol h⁻¹g⁻¹, which simplified the preparation process and promoted industrial application.
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Figure CN122006774A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalysis technology, specifically relating to a poly(heptaquinoneimide) photocatalytic material and its preparation method, as well as a method for photocatalytic preparation of H2O2. Background Technology
[0002] With the rapid development of social science and technology and the continuous advancement of industrialization, human demand for energy is increasing, and global energy security and environmental protection issues are becoming increasingly severe. Developing clean and renewable energy technologies has become an urgent priority. Within this technological field, research on the efficient and orderly conversion of energy and the development of green and clean energy technologies have become a focus of attention. Among numerous solutions, photocatalysis technology can directly utilize solar energy, converting it into chemical energy, providing an effective pathway to achieving sustainable development. Hydrogen peroxide (H2O2) is a strong oxidant widely used in medical and chemical industries. Currently, it is mainly prepared industrially through the anthraquinone process, but this process is complex and accompanied by many byproducts. Photocatalytic water splitting to produce hydrogen peroxide has become a new, green, and clean method for synthesizing hydrogen peroxide, with enormous application prospects.
[0003] The principle of photocatalytic hydrogen peroxide production is as follows: under the irradiation of light with a certain energy, a semiconductor photocatalyst is excited to generate photogenerated electron-hole pairs. These electrons and holes migrate to the catalyst surface and undergo a redox reaction with the reactants. Since the only raw materials for the reaction are water and oxygen, and the required energy can be obtained from sunlight, one of the keys to achieving photocatalytic oxygen reduction to hydrogen peroxide production is finding a non-toxic, inexpensive, efficient, stable, and suitable visible light photocatalyst.
[0004] According to existing research, among various types of photocatalytic materials, crystalline carbon nitride possesses suitable energy bands, good physicochemical stability, and unique two-dimensional structural characteristics. One type, poly(heptaquinoneimide) (PHI), exhibits excellent photocatalytic activity due to its unique large π-conjugated system, which facilitates the migration of photogenerated electrons and holes. Currently, the photocatalytic efficiency of PHI in producing H₂O₂ still needs further improvement. Improving the crystallinity of PHI is considered an important means to further enhance the efficiency of photocatalytic H₂O₂ production; however, current methods are complex and difficult to implement, hindering the industrial application of PHI in the photocatalytic preparation of hydrogen peroxide. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a poly(heptamethrinimide) photocatalytic material, its preparation method, and a method for photocatalytically preparing H2O2. This invention uses dicyandiamide and triaminopyrimidine as raw materials to prepare highly crystalline poly(heptamethrinimide) (PHI) nanorod clusters. The addition of triaminopyrimidine increases the crystallinity of PHI carbon nitride, thereby improving the photocatalytic efficiency of PHI in producing hydrogen peroxide, which is beneficial for the industrial application of photocatalytic hydrogen peroxide production.
[0006] The present invention is specifically implemented through the following technical solutions.
[0007] The first objective of this invention is to provide a method for preparing a poly(heptaazineimide) photocatalytic material, comprising the following steps: A mixture was prepared using dicyandiamide and triaminopyrimidine as raw materials; the molar ratio of dicyandiamide to triaminopyrimidine was 10~30:0.1~3.0. Under a protective gas atmosphere, the mixture is subjected to a first calcination treatment to polymerize melleramine containing a pyrimidine ring; after cooling to room temperature, a second calcination treatment is performed to polymerize melleramine to generate melon-type carbon nitride, thus obtaining precursor powder. The precursor powder was mixed with LiCl / KCl molten salt and then calcined in a protective gas atmosphere to allow melon-type carbon nitride to polymerize into a crystalline structure, thus obtaining poly(heptaquinoneimide) photocatalytic material.
[0008] Preferably, the molar ratio of dicyandiamide to triaminopyrimidine is 20:0.25~2. More preferably, the molar ratio of dicyandiamide to triaminopyrimidine is 20:0.75.
[0009] Preferably, the first step of calcination treatment involves heating the mixture to 450°C at a heating rate of 5°C / min and holding it at that temperature for 2-4 hours (more preferably 4 hours). The second step of calcination treatment involves heating the mixture to 500°C at a heating rate of 5°C / min and holding it at that temperature for 2-4 hours.
[0010] Preferably, the mass ratio of the precursor powder to the LiCl / KCl molten salt is 1:1 to 10. The LiCl / KCl molten salt refers to a mixed salt of LiCl and KCl, with a molar ratio of LiCl to KCl of 59:41 and a melting point of approximately 350°C.
[0011] Preferably, the third step of calcination treatment refers to calcining at 500℃~600℃ at a rate of 5℃ / min for 2 h~4 h, and more preferably, calcining at 550℃ and holding for 2 h.
[0012] Preferably, the mixture is prepared by dissolving dicyandiamide and triaminopyrimidine in water, followed by freeze-drying. 10-30 mmol of dicyandiamide and 0.1-3.0 mmol of triaminopyrimidine are weighed and dissolved in 5-20 mL of water, then directly frozen at -20-40°C and freeze-dried until all water has evaporated.
[0013] Preferably, after heat treatment, the product is cooled to room temperature and then washed and dried with deionized water.
[0014] The second objective of this invention is to provide a poly(heptaquinoneimide) photocatalytic material prepared using the above-described preparation method.
[0015] A third objective of this invention is to provide a method for photocatalytically preparing H2O2, comprising the following steps: using water and oxygen as raw materials, under the photocatalytic action of the aforementioned poly(heptaquinoneimide) photocatalytic material, and under illumination, catalyzing the reaction of water and oxygen to generate H2O2. The ratio of poly(heptaquinoneimide) photocatalytic material to water is 2 mg: 20 mL, or 1 mg: 10 mL.
[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention innovatively proposes the preparation of highly crystalline poly(heptamethrinimide) (PHI) nanorod clusters using dicyandiamide and triaminopyrimidine as raw materials. The prepared carbon nitride exhibits high crystallinity, and the addition of triaminopyrimidine improves the crystallinity of PHI, resulting in excellent visible light absorption performance and significantly enhanced carrier migration efficiency. The raw materials used in this invention are inexpensive and readily available, and the preparation method is simple and easily reproducible.
[0017] This invention, with its suitable band structure and efficient light absorption capacity, exhibits excellent activity and application value in the photocatalytic production of hydrogen peroxide. The highly crystalline nanorod clusters of this invention can stably perform photocatalytic oxygen reduction to hydrogen peroxide production in water without the need for co-catalysts or sacrificial agents, achieving a high hydrogen peroxide production rate. The preparation method of this invention is simple and easy to operate in practical applications, providing a reliable solution for the efficient conduct of photocatalytic hydrogen peroxide production and the development and application of highly crystalline PHI, thus promoting the industrial application of PHI photocatalytic hydrogen peroxide production. Attached Figure Description
[0018] Figure 1 These are X-ray diffraction (XRD) patterns of the photocatalytic materials prepared in Examples 1 to 6 and Comparative Example 1.
[0019] Figure 2 This is a comparison of the intensity of the (100) plane diffraction peaks in the XRD patterns of the photocatalytic materials in Examples 1 to 6 and Comparative Example 1.
[0020] Figure 3These are Fourier transform infrared (FTIR) spectra of the photocatalytic materials prepared in Examples 1 to 6 and Comparative Example 1.
[0021] Figure 4 It is PHI-Py 0.75 Scanning electron microscope (SEM) image.
[0022] Figure 5 It is PHI-Py 0.75 Transmission electron microscope (TEM) images at different magnifications.
[0023] Figure 6 These are the ultraviolet-visible (UV-vis) spectra of the photocatalytic materials of Examples 1 to 6 and Comparative Example 1.
[0024] Figure 7 It is PHI-Py 0.75 Fluorescence spectrum (PL) of PHI.
[0025] Figure 8 The graphs show the visible light catalytic H2O2 production rates of the photocatalytic materials in Examples 1 to 6 and Comparative Example 1. Detailed Implementation
[0026] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention. Unless otherwise specified, the experimental methods and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials described are commercially available.
[0027] This invention discloses a method for preparing highly crystalline PHI photocatalytic materials using dicyandiamide and triaminopyrimidine as precursor materials, comprising the following steps: Step 1: Dissolve 10 mmol-30 mmol of dicyandiamide and 0.1 mmol-3.0 mmol of triaminopyrimidine in 5 mL-20 mL of water, freeze directly at -20 to -40 °C, and then freeze-dry until the water is completely evaporated.
[0028] Step 2: Place the dried solid into a tube furnace and calcine at 450°C for 4 hours in an argon or nitrogen atmosphere. It should be noted that this is the first calcination step. During the first calcination (450°C), dicyandiamide polymerizes to form melleramine. Simultaneously, the polymerization of dicyandiamide and triaminopyrimidine causes the pyrimidine ring to be inserted into the melleramine structure. After cooling, the temperature is raised to 500°C and calcined again in the same atmosphere for 2-4 hours. This is the second calcination step. During the second calcination step, melleramine continues to polymerize to form melon-type carbon nitride. After naturally cooling to room temperature, the precursor powder is obtained.
[0029] Step 3: The obtained precursor powder is thoroughly ground and mixed with a LiCl / KCl mixed salt at a certain mass ratio (1:1-10), and then calcined again at 500℃-600℃ for 2h-4h under the same atmosphere. It should be noted that this is the third calcination step. Melon-type carbon nitride is an amorphous carbon nitride. The high-temperature liquid environment provided by the molten salt can promote mass transfer and further orderly polymerization of carbon nitride structural units to form a crystalline structure. After cleaning and drying, highly crystalline PHI is obtained.
[0030] The PHI obtained through the above preparation steps is in the form of nanorod clusters with high crystallinity, exhibiting excellent visible light absorption performance and significantly improved carrier migration efficiency. The photocatalytic reaction, carried out directly in water, can reduce oxygen to hydrogen peroxide without the need for co-catalysts or sacrificial agents, achieving a reaction rate as high as 4880 μmol / h. -1 g -1 It is 4.5 times that of ordinary PHI. The synthesis method of this invention is simple and the application method is easy to operate, providing a reliable solution for the efficient photocatalytic production of hydrogen peroxide and the development and application of crystalline carbon nitride (PHI).
[0031] The invention will be specifically described below through the following examples and comparative examples. The LiCl / KCl molten salt refers to a mixed salt of LiCl and KCl, with a molar ratio of LiCl to KCl of 59:41 and a melting point of approximately 350°C.
[0032] Example 1 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 0.25 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0033] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0034] Step 3: The obtained precursor powder was ground and thoroughly mixed with LiCl / KCl molten salt at a mass ratio of 1:5. The mixture was then heated to 550℃ at a rate of 5℃ / min under an argon atmosphere and held for 2 h. Finally, the mixture was allowed to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters were obtained, named PHI-Py. 0.25 .
[0035] Prepared PHI-Py 0.25 The product was added to a reaction system for photocatalytic H2O2 production, and the photocatalytic decomposition of water to produce H2O2 was tested. The specific steps are as follows:
[0036] Add 2 mg of PHI-Py to a 100 mL reactor. 0.25 Add 20 mL of water, then purge the reactor with oxygen for 30 minutes to remove air. After purging, turn on the magnetic stirrer to stir, and turn on the xenon lamp for illumination to test the photocatalytic H2O2 production.
[0037] Example 2 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 0.5 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0038] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0039] Step 3: The obtained precursor powder was ground and thoroughly mixed with LiCl / KCl molten salt at a mass ratio of 1:5. The mixture was then heated to 550℃ at a rate of 5℃ / min under an argon atmosphere and held for 2 h. Finally, the mixture was allowed to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters were obtained, named PHI-Py. 0.50 .
[0040] Prepared PHI-Py 0.5 The product was added to a reaction system for photocatalytic H2O2 production, and the photocatalytic decomposition of water to produce H2O2 was tested. The specific steps are as follows:
[0041] Add 2 mg of PHI-Py to a 100 mL reactor. 0.5 Add 20 mL of water, then purge the reactor with oxygen for 30 minutes to remove air. After purging, turn on the magnetic stirrer to stir, and turn on the xenon lamp for illumination to test the photocatalytic H2O2 production.
[0042] Example 3 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 0.75 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0043] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0044] Step 3: The obtained precursor powder was ground and thoroughly mixed with LiCl / KCl molten salt at a mass ratio of 1:5. The mixture was then heated to 550℃ at a rate of 5℃ / min under an argon atmosphere and held for 2 h. Finally, the mixture was allowed to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters were obtained, named PHI-Py. 0.75 .
[0045] Prepared PHI-Py 0.75 The product was added to a reaction system for photocatalytic H2O2 production, and the photocatalytic decomposition of water to produce H2O2 was tested. The specific steps are as follows:
[0046] Add 2 mg of PHI-Py to a 100 mL reactor. 0.75 Add 20 mL of water, then purge the reactor with oxygen for 30 minutes to remove air. After purging, turn on the magnetic stirrer to stir, and turn on the xenon lamp for illumination to test the photocatalytic H2O2 production.
[0047] Example 4 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 1.0 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0048] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0049] Step 3: The obtained precursor powder was ground and thoroughly mixed with LiCl / KCl molten salt at a mass ratio of 1:5. The mixture was then heated to 550℃ at a rate of 5℃ / min under an argon atmosphere and held for 2 h. Finally, the mixture was allowed to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters were obtained, named PHI-Py. 1.00 .
[0050] Prepared PHI-Py 1.00 The product was added to a reaction system for photocatalytic H2O2 production, and the photocatalytic decomposition of water to produce H2O2 was tested. The specific steps are as follows:
[0051] Add 2 mg of PHI-Py to a 100 mL reactor. 1.00 Add 20 mL of water, then purge the reactor with oxygen for 30 minutes to remove air. After purging, turn on the magnetic stirrer to stir, and turn on the xenon lamp for illumination to test the photocatalytic H2O2 production.
[0052] Example 5 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 1.5 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0053] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0054] Step 3: The obtained precursor powder was ground and thoroughly mixed with LiCl / KCl molten salt at a mass ratio of 1:5. The mixture was then heated to 550℃ at a rate of 5℃ / min under an argon atmosphere and held for 2 h. Finally, it was allowed to cool naturally to room temperature. After washing and drying the sample with deionized water, the highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters were obtained and named PHI-Py. 1.50 .
[0055] Prepared PHI-Py 1.50 The product was added to a reaction system for photocatalytic H2O2 production, and the photocatalytic decomposition of water to produce H2O2 was tested. The specific steps are as follows:
[0056] Add 2 mg of PHI-Py to a 100 mL reactor. 1.50Add 20 mL of water, then purge the reactor with oxygen for 30 minutes to remove air. After purging, turn on the magnetic stirrer to stir, and turn on the xenon lamp for illumination to test the photocatalytic H2O2 production.
[0057] Example 6 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 2.0 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0058] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process begins with heating to 450℃ at 5℃ / min under an argon atmosphere and holding for 4 hours, followed by natural cooling to room temperature. Then, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0059] Step 3: The obtained precursor powder was ground and thoroughly mixed with LiCl / KCl molten salt at a mass ratio of 1:5. The mixture was then heated to 550℃ at a rate of 5℃ / min under an argon atmosphere and held for 2 h. Finally, the mixture was allowed to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters were obtained, named PHI-Py. 2.00 .
[0060] Prepared PHI-Py 2.00 The product was added to a reaction system for photocatalytic H2O2 production, and the photocatalytic decomposition of water to produce H2O2 was tested. The specific steps are as follows:
[0061] Add 2 mg of PHI-Py to a 100 mL reactor. 2.00 Add 20 mL of water, then purge the reactor with oxygen for 30 minutes to remove air. After purging, turn on the magnetic stirrer to stir, and turn on the xenon lamp for illumination to test the photocatalytic H2O2 production.
[0062] Example 7 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 0.75 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0063] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0064] Step 3: Grind the obtained precursor powder with LiCl / KCl molten salt at a mass ratio of 1:1 until fully mixed. Then, heat the mixture to 500℃ at 5℃ / min under an argon atmosphere and hold for 3 h. Finally, allow it to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters are obtained.
[0065] Example 8 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 20 mmol of dicyandiamide and 0.75 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0066] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0067] Step 3: Grind the obtained precursor powder with LiCl / KCl molten salt at a mass ratio of 1:10 until fully mixed. Then, heat the mixture to 600℃ at 5℃ / min under an argon atmosphere and hold for 4 hours. Finally, allow it to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters are obtained.
[0068] Example 9 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 10 mmol of dicyandiamide and 0.75 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0069] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0070] Step 3: Grind the obtained precursor powder with LiCl / KCl molten salt at a mass ratio of 1:5 until fully mixed. Then, heat the mixture to 550℃ at 5℃ / min under an argon atmosphere and hold for 2 h. Finally, allow it to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters are obtained.
[0071] Example 10 A method for preparing a poly(heptaazineimide) photocatalytic material includes the following steps: Step 1: Weigh 30 mmol of dicyandiamide and 0.75 mmol of triaminopyrimidine and dissolve them in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0072] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0073] Step 3: Grind the obtained precursor powder with LiCl / KCl molten salt at a mass ratio of 1:5 until fully mixed. Then, heat the mixture to 550℃ at 5℃ / min under an argon atmosphere and hold for 2 h. Finally, allow it to cool naturally to room temperature. After washing and drying the sample with deionized water, highly crystalline poly(heptaquinoneimide) (PHI) nanorod clusters are obtained.
[0074] Comparative Example 1 PHI, or PHI without added triaminopyrimidine, is prepared by the following steps: Step 1: Weigh 20 mmol of dicyandiamide and dissolve it in 10 mL of water. Freeze the solution directly and then freeze-dry it.
[0075] Step 2: Transfer the dried solid to a small crucible and place it in a tube furnace for calcination. The calcination process is as follows: first, the temperature is increased to 450℃ at 5℃ / min under an argon atmosphere and held for 4 hours, then naturally cooled to room temperature. Next, the temperature is increased to 500℃ at 5℃ / min and held for 2 hours. After the tube furnace has naturally cooled to room temperature, the precursor powder is obtained.
[0076] Step 3: Grind the obtained precursor powder with LiCl / KCl molten salt at a mass ratio of 1:5 until fully mixed. Then, heat the mixture to 550℃ at 5℃ / min under an argon atmosphere and hold for 2 h. Finally, allow it to cool naturally to room temperature. After washing and drying the sample with deionized water, PHI is obtained.
[0077] Figure 1This is the X-ray diffraction (XRD) pattern of the highly crystalline PHI prepared in this invention. As can be seen from the figure, all samples have two distinct characteristic peaks, corresponding to the (100) plane and (002) crystal plane of PHI, respectively. As the content of triaminopyrimidine gradually increases, the (100) plane diffraction peak of PHI-Py gradually strengthens.
[0078] Figure 2 This is a comparison of the intensity of the (100) plane diffraction peaks in the XRD patterns of different PHI samples. As the content of triaminopyrimidine gradually increases, the (100) plane diffraction peak of PHI-Py0.75 is the strongest. With further increases in the content of triaminopyrimidine, the (100) plane diffraction peak gradually decreases. A stronger diffraction peak intensity indicates higher crystallinity of the material. This suggests that the addition of an appropriate amount of triaminopyrimidine can significantly enhance the crystallinity of PHI. When the content of triaminopyrimidine continues to increase, excessive triaminopyrimidine affects the structural stability of PHI, leading to a decrease in crystallinity. 0.75 The sample with the optimal ratio exhibits the highest crystallinity.
[0079] Figure 3 This is the Fourier transform infrared (FTIR) spectrum of the highly crystalline PHI prepared by this invention. All samples show the characteristic peaks of PHI, indicating that crystalline PHI can be successfully prepared using dicyandiamide and triaminopyrimidine.
[0080] Figure 4 This is a scanning electron microscope (SEM) image of the highly crystalline PHI prepared according to the present invention, using PHI-Py 0.75 For example, as can be seen from the figure, the microstructure of PHI is a cluster of nanorods. This nanorod morphology helps to shorten the migration distance of photogenerated carriers to the catalyst surface and reduce the recombination rate of the carriers. Figure 7 As shown.
[0081] Figure 5 The highly crystalline PHI-Py prepared in this invention 0.75 Transmission electron microscopy (TEM) images at different magnifications show good crystallinity and relatively clear lattice fringes.
[0082] Figure 6 This is the UV-Vis absorption spectrum of the highly crystalline PHI prepared in this invention. As can be seen from the figure, with the increase of the amount of triaminopyrimidine added, the absorption edge of the synthesized sample gradually increases and extends to about 650 nm, indicating that the crystalline carbon nitride prepared in this invention can utilize more sunlight and generate more photogenerated carriers, thereby improving the photocatalytic activity for hydrogen peroxide production.
[0083] Figure 7This is the fluorescence spectrum (PL) of the highly crystalline PHI prepared in this invention. The spectrum shows the PHI-Py synthesized by introducing triaminopyrimidine. 0.75 The fluorescence intensity is lower than that of ordinary PHI, indicating that the crystalline PHI prepared in this invention can effectively suppress the recombination of photogenerated electrons and holes and improve the efficiency of photocatalytic hydrogen production.
[0084] Figure 8 This is a visible light photocatalytic H2O2 production rate diagram of the crystalline carbon nitride prepared in this invention, using PHI-Py synthesized in the most suitable ratio. 0.75 The highest rate of hydrogen peroxide production was achieved by visible light photocatalysis, reaching 4880 μmol / h. -1 g -1 .
[0085] Examples 7 through 10 also prepared highly crystalline poly(heptamethrinimide) (PHI) nanorod clusters, with properties similar to those in Example 3, and will not be described in detail here.
[0086] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.
Claims
1. A method for preparing a poly(heptaazineimide) photocatalytic material, characterized in that, Includes the following steps: A mixture was prepared using dicyandiamide and triaminopyrimidine as raw materials; the molar ratio of dicyandiamide to triaminopyrimidine was 10~30:0.1~3.
0. Under a protective gas atmosphere, the mixture is subjected to a first calcination treatment to polymerize melleramine containing a pyrimidine ring; after cooling to room temperature, a second calcination treatment is performed to polymerize melleramine to generate melon-type carbon nitride, thus obtaining precursor powder. The precursor powder was mixed with LiCl / KCl molten salt and then calcined in a protective gas atmosphere to allow melon-type carbon nitride to polymerize into a crystalline structure, thus obtaining poly(heptaquinoneimide) photocatalytic material.
2. The method for preparing the poly(heptaazineimide) photocatalytic material according to claim 1, characterized in that, The molar ratio of dicyandiamide to triaminopyrimidine is 20:0.25~2.
3. The method for preparing the poly(heptaazineimide) photocatalytic material according to claim 1, characterized in that, The first step of calcination treatment involves heating the mixture to 450℃ and holding it at that temperature for 2 to 4 hours. The second step of calcination treatment involves heating the mixture to 500℃ and holding it at that temperature for 2 to 4 hours.
4. The method for preparing the poly(heptaazineimide) photocatalytic material according to claim 1, characterized in that, The mass ratio of precursor powder to LiCl / KCl molten salt is 1:1~10. LiCl / KCl molten salt refers to a mixed salt of LiCl and KCl, and the molar ratio of LiCl to KCl is 59:
41.
5. The method for preparing the poly(heptaazineimide) photocatalytic material according to claim 1, characterized in that, The third step, calcination, involves heating the temperature to 500℃~600℃ and calcining for 2 to 4 hours.
6. The method for preparing the poly(heptaazineimide) photocatalytic material according to claim 1, characterized in that, The mixture is prepared by dissolving dicyandiamide and triaminopyrimidine in water and then freeze-drying the mixture.
7. A poly(heptaazineimide) photocatalytic material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.
8. The poly(heptaazineimide) photocatalytic material according to claim 7, characterized in that, The poly(heptaazimineimide) photocatalytic material is in the form of nanorod clusters.
9. A method for photocatalytic preparation of H2O2, characterized in that, The process includes the following steps: using water and oxygen as raw materials, under the photocatalytic action of the poly(heptaquinoneimide) photocatalytic material as described in claim 7, light is applied to catalyze the reaction of water and oxygen to generate H2O2.