A three-dimensional hollow porous n-doped graphite phase carbon nitride with enhanced built-in electric field and a preparation method and application thereof

Abstract

The application discloses a three-dimensional hollow porous N-doped graphite phase carbon nitride with an enhanced built-in electric field and a preparation method and application thereof, and belongs to the technical field of wastewater degradation of aromatic ring-containing pollutants. The application utilizes guanidine carbonate and a hydrogen bond interactive cyanuric acid and melamine supermolecular structure to form a precursor microenvironment capable of being regulated and self-assembled, so that the prepared material has a high specific surface area, more reaction sites and adsorption capacity for pollutants; meanwhile, N doping controls the energy band structure, and enhances the light absorption utilization rate; the generation of C vacancies causes perfect capture of photo-generated electrons, and greatly inhibits electron-hole recombination. In addition, the addition of nitrogen and the generation of C vacancies cause significant redistribution of charges around the active sites, so that electrons are rapidly captured and accumulated on the surface, a strong built-in electric field is formed, which is beneficial to the separation and transport of photo-generated carriers, and thus the activity of the original carbon nitride in visible light catalytic degradation of aromatic ring-containing pollutants is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of wastewater degradation technology containing aromatic ring pollutants, and more specifically relates to a three-dimensional hollow porous N-doped graphitic carbon nitride with enhanced built-in electric field, its preparation method and application. Background Technology

[0002] With the acceleration of industrialization and urbanization, the large-scale use and emission of pollutants containing aromatic compounds (dyes, antibiotics, phenols, etc.) seriously threaten human health. Addressing the problems of low efficiency, complex operation, high cost, and potential secondary pollution associated with existing treatment methods, developing an efficient and eco-friendly method for removing pollutants from the aquatic environment has become a hot topic in academia and industry. Novel semiconductor photocatalysis technology is a green technology that utilizes semiconductors to convert solar energy into high-energy chemical energy, showing great promise for applications in renewable clean energy production and pollutant degradation.

[0003] Photocatalytic oxidation technology based on solar energy has attracted widespread attention as an economical, convenient, and green wastewater purification technology. As previously reported, the metal-free semiconductor g-C3N4, due to its suitable bandgap structure (2.7 eV), high stability, and visible light response, has experienced explosive growth in photocatalysis research and is considered a next-generation photocatalyst. However, insufficient active sites and severe recombination of photogenerated carriers limit its widespread practical application. Therefore, it is necessary to design photocatalysts with high charge separation and multiple active centers to achieve efficient degradation and deep mineralization, while ensuring simple and low-cost preparation processes to promote the efficient development of photocatalysis technology.

[0004] Guanidine carbonate has a simple molecular structure, strong hydrogen bond donor and acceptor capabilities, and a flexible cation center. Intermolecular interactions can be modulated by changing the coordination geometry or the type of anion, forming a stable hydrogen bond network with cyanuric acid and melamine molecules. The precursor microenvironment formed by this interaction ensures a high degree of controllability of the precursor structure, promoting supramolecular ordered assembly, controlling the morphology of carbon nitride, and, moreover, the nitrogen-rich nature of guanidine carbonate. Its introduction into the material structure (especially doping at the C1 site) significantly alters the local electron density distribution. The generation of C vacancies leads to the perfect capture of photogenerated electrons, greatly suppressing electron-hole recombination. This doping method creates a non-uniform charge distribution around the active site, forming a strong local built-in electric field, providing a powerful driving force for the separation of photogenerated electrons and holes. Furthermore, as a precursor molecule, guanidine carbonate does not contain metals or heteroatoms, avoiding the possibility of introducing foreign impurities during the synthesis process. Summary of the Invention

[0005] The purpose of this invention is to provide a three-dimensional hollow porous N-doped graphitic carbon nitride with an enhanced built-in electric field, its preparation method, and its application, in order to solve the problems existing in the prior art, prepare a photocatalyst with high charge separation and multiple active centers to achieve efficient degradation and deep mineralization, while making the preparation process simple and low-cost, thus promoting the efficient development of photocatalysis technology.

[0006] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is to provide a method for preparing three-dimensional hollow porous N-doped graphitic carbon nitride with an enhanced built-in electric field, comprising the following steps: Melamine, cyanuric acid, and guanidine carbonate were dissolved in a solvent, and then sequentially mixed, dried, and heated under a nitrogen atmosphere to obtain the three-dimensional hollow porous N-doped graphitic carbon nitride with an enhanced built-in electric field.

[0007] Preferably, the molar ratio of melamine, cyanuric acid and guanidine carbonate is 1:1:1.5.

[0008] The molar ratio of melamine, cyanuric acid, and guanidine carbonate determines the stability of the hydrogen bond network, increases the number of hydrogen bond donors / acceptors in the system, and helps to construct a more compact and regular supramolecular framework, thereby promoting ordered three-dimensional assembly. Guanidine carbonate is rich in nitrogen; appropriately increasing its molar ratio (1:1:1.5) not only helps to introduce more nitrogen atoms, which is beneficial for forming local charges at the C1 site, but also generates C vacancies from the etching gas produced during decomposition, which facilitates the perfect capture of photogenerated electrons and greatly suppresses electron-hole recombination. This doping method creates a non-uniform charge distribution around the active sites, forming a strong local built-in electric field, providing a powerful driving force for the separation of photogenerated electrons and holes. The increased strength of the built-in electric field promotes the separation and migration of photogenerated electron-hole pairs.

[0009] Preferably, the solvent includes ethanol.

[0010] Preferably, the mixing temperature is 45~80°C. The time is 1 to 3 hours.

[0011] Preferably, the drying process includes: drying at 60-100°C. Dry overnight.

[0012] Preferably, the temperature of the heat treatment is 540~560°C. The heating rate is 2 / min, heat preservation time is 2~4h.

[0013] Furthermore, the temperature of the heat treatment is 550°C. The heating rate is 2 / min, heat preservation time is 2h.

[0014] The second technical solution of the present invention provides a three-dimensional hollow porous N-doped graphitic carbon nitride with an enhanced built-in electric field prepared by the above preparation method.

[0015] Preferably, the specific surface area of ​​the three-dimensional hollow porous N-doped graphitic carbon nitride with enhanced built-in electric field can reach 67.78 m². 2 / g, with an average fluorescence lifetime of up to 11.96ns.

[0016] The third technical solution of the present invention provides the application of the above-mentioned three-dimensional hollow porous N-doped graphitic carbon nitride with enhanced built-in electric field in the degradation of wastewater containing aromatic pollutants.

[0017] Preferably, the wastewater degradation containing aromatic pollutants includes the degradation of wastewater containing one or more of Rhodamine B, antibiotics, benzene, toluene, phenol, 4-chlorophenol, and 2,4-dichlorophenol.

[0018] The technical principle of this invention is as follows: This invention utilizes the supramolecular structure of guanidine carbonate with cyanuric acid and melamine, which have hydrogen-bonded interactions, to form a tunable self-assembly precursor microenvironment. Guanidine carbonate can generate additional hydrogen bonds or electrostatic interactions with the cyanuric acid / melamine complex, acting as an "assembly edge terminator." Guanidine carbonate binds to the surface of the complex to change its morphology and expose active sites, altering the self-assembly mode of the system. The precursor morphology changes from a pancake shape to a stacked nanoflower shape, and further, a three-dimensional hollow box-shaped carbon nitride is synthesized through thermal polymerization. The modified graphitic carbon nitride prepared by this invention exhibits a three-dimensional porous hollow box-shaped structure with a significantly increased specific surface area, providing more reaction sites and adsorption capacity for pollutants. Simultaneously, N doping modulates its band structure, enhancing light absorption utilization, and the generation of C vacancies leads to the perfect capture of photogenerated electrons, greatly suppressing electron-hole recombination.

[0019] Construction of the three-dimensional structure: Its unique porous structure helps enhance the adsorption and enrichment of pollutants, thereby improving surface reactivity. On the other hand, its highly open morphology exposes more active sites, which is conducive to the formation of more photogenerated charge carriers participating in the reaction. In addition, the rich and open multi-channel structure allows multiple reflections of the light source, thereby improving light absorption capacity. This invention constructs a supramolecular self-assembly precursor carbon nitride by arranging ordered molecules into stable aggregates through non-covalent bonds. This is a promising three-dimensional structure construction strategy that can be used to develop novel carbon nitrides with a higher degree of control at the molecular level. Hydrogen bond interactions are unique, directional, specific, and reversible, and can be used to control molecular self-assembly. By adjusting hydrogen bonds, this invention can intervene in the self-assembly process and adjust the surface and electronic structures of the precursor, so that the prepared modified graphitic carbon nitride exhibits a well-defined morphology, high surface area, and excellent photocatalytic performance.

[0020] Formation of the built-in electric field: In this invention, N doping occurs at the C1 site of carbon nitride. The addition of nitrogen leads to a significant redistribution of charge around the active site, resulting in rapid electron capture and accumulation on the surface, forming a strong built-in electric field. This is beneficial for the separation and transport of photogenerated carriers, thereby greatly improving the activity of the original carbon nitride in the visible light photocatalytic degradation of rhodamine B. The generation of C vacancies leads to the perfect capture of photogenerated electrons, greatly suppressing electron-hole recombination. The built-in electric field is an electric field generated in semiconductor materials due to the uneven distribution of charge in different regions, and it plays a positive role in the separation of photogenerated charges.

[0021] The present invention discloses the following technical effects: (1) The three-dimensional graphitic carbon nitride prepared by this invention has a three-dimensional hollow porous structure, which greatly increases its specific surface area and helps to enhance the adsorption and enrichment of pollutants; (2) Its highly open morphology is conducive to exposing more active sites and forming more photogenerated carriers participating in the reaction; (3) Appropriate N doping can effectively adjust its band structure while avoiding the introduction of foreign atoms, and the oxidation ability of the material is enhanced; (4) When nitrogen atoms are incorporated at C1 sites, they will change the local electron density of the material, which will lead to the redistribution of charges around the active sites, resulting in uneven local charges in the doped region. The generation of C vacancies leads to the perfect capture of photogenerated electrons, which can greatly suppress electron-hole recombination, form a stronger internal electric field, and improve the separation efficiency of its photogenerated carriers, thereby improving the performance of the catalyst in the visible light catalytic degradation of Rhodamine B. Attached Figure Description

[0022] Figure 1 ECN0(a) and ECN in Examples 1-6 1.5 (b) SEM image of the precursor; Figure 2PCN(a) of Example 6 and ECN prepared in Example 4 1.5 (b) Transmission electron micrograph; Figure 3 Fourier transform infrared spectra of PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1-5; Figure 4 The N2 adsorption-desorption isotherms are for PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1 and 4. Figure 5 XRD diffraction patterns of PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1-5; Figure 6 The PCN of Example 6 and the ECN prepared in Example 4 1.5 The time-resolved transient photoluminescence decay curve and the listed curve fitting parameter graph; Figure 7 The PCN of Example 6 and the ECN prepared in Example 4 1.5 EPR spectrum; Figure 8 The degradation performance of PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1-5 for the photocatalytic degradation of Rh B is shown in (a) and pseudo-first-order kinetic reaction curve (b). Figure 9 ECN prepared in Example 4 1.5 Cyclic stability diagram of photocatalytic degradation of Rhodamine B as a catalyst. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0029] Unless otherwise specified, all raw materials used in this invention are commercially available products, and the source of these commercially available products does not affect the technical effect of this invention.

[0030] Example 1 This embodiment provides the preparation of the modified graphitic carbon nitride and its application in the degradation of the dye Rhodamine B: The first step is to dissolve melamine and cyanuric acid in 25 mL of ethanol at a molar ratio of 1:1.

[0031] The second step is to vigorously stir the mixture for 1 hour to ensure uniform mixing, and then... Dry overnight (12h).

[0032] The third step is to place the white powder obtained in the second step under a nitrogen atmosphere at a concentration of 2... Heating rate increased to 550 °C / min The modified graphitic carbon nitride (ECNO) was obtained by heating for 2 hours.

[0033] Fourth step: Weigh 10 mg of the prepared modified graphitic carbon nitride (ECNO) into a photocatalytic tube, add dye RhB (40 mg / L), stir in the dark for 30 min, and then react under visible light.

[0034] Example 2 This embodiment provides the preparation of the modified graphitic carbon nitride and its application in the degradation of the dye Rhodamine B: The first step is to dissolve melamine, cyanuric acid, and guanidine carbonate in 25 mL of ethanol at a molar ratio of 1:1:0.5.

[0035] The second step is to vigorously stir the mixture for 1 hour to ensure uniform mixing, and then... Dry overnight (12h).

[0036] The third step is to place the white powder obtained in the second step under a nitrogen atmosphere at a concentration of 2... Heating rate increased to 550 °C / min The modified graphitic carbon nitride (ECN) was obtained by heating for 2 hours. 0.5 ).

[0037] Step 4: Weigh 10 mg of the prepared modified graphitic carbon nitride (ECN). 0.5 Add dye RhB (40 mg / L) to the photocatalytic tube, stir in the dark for 30 min, and then react under visible light.

[0038] Example 3 This embodiment provides the preparation of the modified graphitic carbon nitride and its application in the degradation of the dye Rhodamine B: The first step is to dissolve melamine, cyanuric acid, and guanidine carbonate in 25 mL of ethanol at a molar ratio of 1:1:1.

[0039] The second step is to vigorously stir the mixture for 1 hour to ensure uniform mixing, and then... Dry overnight (12h).

[0040] The third step is to place the white powder obtained in the second step under a nitrogen atmosphere at a concentration of 2... Heating rate increased to 550 °C / min The modified graphitic carbon nitride (ECN1) was obtained by holding the temperature for 2 hours.

[0041] Fourth step: Weigh 10 mg of the prepared modified graphitic carbon nitride (ECN1) into a photocatalytic tube, add dye RhB (40 mg / L), stir in the dark for 30 min, and then react under visible light.

[0042] Example 4 This embodiment provides the preparation of the modified graphitic carbon nitride and its application in the degradation of the dye Rhodamine B: The first step is to dissolve melamine, cyanuric acid, and guanidine carbonate in 25 mL of ethanol at a molar ratio of 1:1:1.5.

[0043] The second step is to vigorously stir the mixture for 1 hour to ensure uniform mixing, and then... Dry overnight (12h).

[0044] The third step is to place the white powder obtained in the second step under a nitrogen atmosphere at a concentration of 2... Heating rate increased to 550 °C / min The modified graphitic carbon nitride (ECN) was obtained by heating for 2 hours. 1.5 ).

[0045] Step 4: Weigh 10 mg of the prepared modified graphitic carbon nitride (ECN). 1.5 Add dye RhB (40 mg / L) to the photocatalytic tube, stir in the dark for 30 min, and then react under visible light.

[0046] Example 5 This embodiment provides the preparation of the modified graphitic carbon nitride and its application in the degradation of the dye Rhodamine B: The first step is to dissolve melamine, cyanuric acid, and guanidine carbonate in 25 mL of ethanol at a molar ratio of 1:1:2.

[0047] The second step is to vigorously stir the mixture for 1 hour to ensure uniform mixing, and then... Dry overnight (12h).

[0048] The third step is to place the white powder obtained in the second step under a nitrogen atmosphere at a concentration of 2... Heating rate increased to 550 °C / min The modified graphitic carbon nitride (ECN2) was obtained by heating for 2 hours.

[0049] Fourth step: Weigh 10 mg of the prepared modified graphitic carbon nitride (ECN2) into a photocatalytic tube, add dye RhB (40 mg / L), stir in the dark for 30 min, and then react under visible light.

[0050] Example 6 This embodiment provides the preparation of the carbon nitride and its application in the degradation of the dye Rhodamine B: The first step is to expose melamine to a nitrogen atmosphere at a concentration of 2... Heating rate increased to 550 °C / min After holding at this temperature for 2 hours, carbon nitride (PCN) was obtained.

[0051] The second step involves weighing 10 mg of the prepared carbon nitride (PCN) into a photocatalytic tube, adding dye Rh B (40 mg / L), stirring in the dark for 30 minutes, and then reacting under visible light.

[0052] Example 7 This embodiment provides the preparation of the modified graphitic carbon nitride (Example 4) and its application in the degradation of the dye Rhodamine B: The first step is to dissolve melamine, cyanuric acid, and guanidine carbonate in 25 mL of ethanol at a molar ratio of 1:1:1.5.

[0053] The second step is to vigorously stir the mixture for 1 hour to ensure uniform mixing, and then... Dry overnight (12h).

[0054] The third step is to place the white powder obtained in the second step under a nitrogen atmosphere at a concentration of 2... Heating rate increased to 550 °C / min The modified graphitic carbon nitride (ECN) was obtained by heating for 2 hours. 1.5 ).

[0055] Step 4: Weigh 10 mg of the prepared modified graphitic carbon nitride (ECN). 1.5 Add dye RhB (40 mg / L) to the photocatalytic tube, stir in the dark for 30 min, and then react under visible light.

[0056] In the fifth step, after completing one photocatalytic degradation cycle, the catalyst was filtered, rinsed with deionized water, and dried to remove residues and maintain its activity. It was then used in multiple rounds of Rhodamine B cyclic degradation experiments to evaluate the catalyst's reusability and stability. This step verified the catalyst's structural durability, activity retention capability, and feasibility in practical applications.

[0057] Figure 1 ECN0(a) and ECN in Examples 1-6 1.5 (b) SEM image of the precursor.

[0058] Depend on Figure 1 It can be seen that the precursor morphology of the prepared catalyst changes from plate-like to clustered flower-like.

[0059] Figure 2 PCN(a) of Example 6 and ECN prepared in Example 4 1.5 (b) Transmission electron micrograph.

[0060] Depend on Figure 2 It can be seen that, compared with the sheet-like structure of traditional calcined PCN catalysts, the modified catalyst synthesized N-doped three-dimensional hollow box-shaped g-C3N4 through thermal polymerization.

[0061] Table 1. C / N molar ratios and surface group concentrations of various samples of PCN from Example 6 and modified graphitic carbon nitride prepared in Examples 1-5, as determined by XPS. As shown in Table 1, the introduction of guanidine carbonate alters the assembly of the supramolecular structure, and N atoms may be introduced into the g-C3N4 framework.

[0062] Figure 3 Fourier transform infrared spectra of PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1-5.

[0063] Depend on Figure 3 It can be seen that ECNx is at 801, 1000-1700 and 3000-3400 cm. -1 The characteristic peaks of PCN are displayed at 3073 and 3180 cm⁻¹, further indicating that the g-C₃N₄ backbone in the ECNx sample remained almost unchanged. These peaks are particularly prominent at 3073 and 3180 cm⁻¹. -1 At the site of observation, NH stretching patterns of residual nitrogen precursor species were observed in all ECNx samples, which may have partially contributed to the detection of excess nitrogen in elemental analysis. The lack of a significant enhancement in NH bond strength also ruled out the possibility that the increase in residual NH2 originated from incompletely polymerized material.

[0064] Table 2. Carbon and nitrogen binding energies and percentages of different valence bonds of PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1-5, as determined by XPS. As shown in Table 2, compared to PCN, ECN... 1.5 The intensity (peak area) of the N-C=N bond in the sample increased significantly, while the intensity of the C-N bond decreased significantly. According to Table 2, the intensity ratio of the CN bond to the NC=N bond, ECN... 1.5 (0.08) lower than g-C3N4 (0.35), the strength ratio of bond (CN=C) / bond (N-(C)3, ECN 1.5 (4.46) is higher than g-C3N4 (4.1), indicating that N atoms can replace C in the framework of g-C3N4.

[0065] Figure 4 The N2 adsorption-desorption isotherms are for PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1 and 4.

[0066] Depend on Figure 4 It can be seen that this indicates ECN 1.5 The three-dimensional network structure exhibits mesoporous characteristics. Specifically, ECN 1.5 The BET specific surface area and pore volume of the BET are 1.63 times and 8.73 times that of the PCN, respectively. This creates more favorable conditions for the adsorption and degradation of pollutants. Figure 5 XRD diffraction patterns of PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1-5.

[0067] Depend on Figure 5It can be seen that, compared with PCN, all samples have stronger diffraction peaks at 13.1° and 27.4°, indicating that the introduction of guanidine carbonate changed the assembly of the supramolecular structure.

[0068] Figure 6 The PCN of Example 6 and the ECN prepared in Example 4 1.5 The time-resolved transient photoluminescence decay curve and the listed curve fitting parameter graph are shown.

[0069] Depend on Figure 6 It can be seen that PCN and ECN 1.5 The average fluorescence lifetimes (τA) were 5.99 ns and 11.96 ns, respectively. Compared with PCN, ECN... 1.5 It exhibits a longer carrier lifetime and separation efficiency.

[0070] Figure 7 The PCN of Example 6 and the ECN prepared in Example 4 1.5 The EPR spectrum.

[0071] Depend on Figure 7 It can be seen that PCN and ECN 1.5 It exhibits a single Lorentz line with a g-value of 2.004, which can be attributed to unpaired electrons. (This is in contrast to PCN and ECN.) 1.5 Compared to the samples, ECN 1.5 It has a higher EPR signal strength. A higher EPR strength indicates ECN. 1.5 There is a high concentration of unpaired electrons in it. This is attributed to the introduction of carbon vacancies into the heptaazine unit, thereby generating more unsaturated centers corresponding to unpaired electrons in g-C3N4.

[0072] Figure 8 The degradation performance of PCN in Example 6 and modified graphitic carbon nitride prepared in Examples 1-5 for the photocatalytic degradation of Rh B is shown in (a) and pseudo-first-order kinetic reaction curve (b).

[0073] Depend on Figure 8 It can be seen that when RhB is degraded under visible light, the degradation rate of ECN0 obtained in Example 1 reaches 0.019 min. -1 ECN obtained in Example 2 0.5 The degradation rate reached 0.082 min. -1 The degradation rate of ECN1 obtained in Example 3 reached 0.086 min. -1 ECN obtained in Example 4 1.5 The degradation rate reached 0.105 min. -1 The degradation rate of ECN2 obtained in Example 5 reached 0.043 min. -1The degradation rate of PCN obtained in Example 6 was only 0.006 min. -1 .

[0074] Figure 9 ECN prepared in Example 4 1.5 Cyclic stability diagram of photocatalytic degradation of Rhodamine B as a catalyst.

[0075] Depend on Figure 9 It can be seen that the prepared ECN 1.5 As a catalyst, it exhibits good cycle stability in the photocatalytic degradation of RhB.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing three-dimensional hollow porous N-doped graphitic carbon nitride with enhanced built-in electric field, characterized in that, Includes the following steps: Melamine, cyanuric acid, and guanidine carbonate were dissolved in a solvent, and then sequentially mixed, dried, and heated under a nitrogen atmosphere to obtain the three-dimensional hollow porous N-doped graphitic carbon nitride with an enhanced built-in electric field.

2. The preparation method according to claim 1, characterized in that, The molar ratio of melamine, cyanuric acid and guanidine carbonate is 1:1:1.

5.

3. The preparation method according to claim 1, characterized in that, The solvent includes ethanol.

4. The preparation method according to claim 1, characterized in that, The mixing temperature is 45-80°C. The time is 1 to 3 hours.

5. The preparation method according to claim 1, characterized in that, The drying process includes: drying at 60~100°C. Dry overnight.

6. The preparation method according to claim 1, characterized in that, The temperature of the heat treatment is 540~560℃. The heating rate is 2 / min, heat preservation time is 2~4h.

7. The preparation method according to claim 6, characterized in that, The temperature of the heat treatment is 550°C. The heating rate is 2 / min, heat preservation time is 2h.

8. The three-dimensional hollow porous N-doped graphitic carbon nitride with enhanced built-in electric field prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the three-dimensional hollow porous N-doped graphitic carbon nitride with an enhanced built-in electric field as described in claim 8 in the degradation of wastewater containing aromatic ring pollutants.

10. The application according to claim 9, characterized in that, The degradation of wastewater containing aromatic pollutants includes the degradation of wastewater containing Rhodamine B.

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