A porous tubular graphite phase carbon nitride, a photocatalyst, and its preparation method and application

Abstract

The present invention discloses a porous tubular graphite-phase carbon nitride, a photocatalyst, a preparation method thereof, and an application thereof. The preparation method of the photocatalyst comprises the following steps: (2.1) adding acetic acid to a melamine aqueous solution to obtain a mixed solution; (2.2) subjecting the mixed solution to a hydrothermal reaction, filtering the mixed solution, washing and drying the obtained filter residue to obtain a carbon nitride precursor; (2.3) mixing the carbon nitride precursor with Mn-MOF, grinding the mixture to obtain a mixed powder; and (2.4) calcining the mixed powder. The preparation process and operation method of the present invention are simple. A pre-assembly-thermal polymerization strategy is used to introduce single Mn atoms into the six-fold cavity of the graphite-phase carbon nitride 3-s-triazine structure, effectively improving the electron migration rate of the graphite-phase carbon nitride. At the same time, a porous tubular graphite-phase carbon nitride is constructed, so that the catalyst has more efficient photocatalytic degradation of antibiotic pollutants and decomposition of water to produce hydrogen.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysts, and in particular to a porous tubular graphite phase carbon nitride, a photocatalyst, and a preparation method and application thereof. Background Art

[0002] Graphitic carbon nitride (g-C3N4) is a semiconductor material with the advantages of being non-toxic, inexpensive, readily available, having a wide visible light response range, and an adjustable band gap. It has been widely used in the field of photocatalysis. At the same time, g-C3N4 has a planar conjugated structure composed of 3-s-triazine units. The six lone pairs of electrons on the N atom in the 3-s-triazine structure can effectively anchor metal atoms. The introduction of single metal atoms can increase the active sites of the catalyst, construct new electron transfer pathways, and improve the migration rate of photogenerated electrons and holes.

[0003] However, the g-C3N4 structure prepared by traditional thermal polymerization method is blocky or lamellar, with a small specific surface area, limited active sites, a fast recombination rate of photogenerated electron-hole pairs, a band gap of about 2.7eV, and mainly absorbs visible light with a wavelength less than 460nm. It has low utilization efficiency of long-wavelength visible light and infrared light, resulting in low photocatalytic efficiency. Summary of the Invention

[0004] The main purpose of the present invention is to provide a porous tubular graphite phase carbon nitride, a photocatalyst and a preparation method and application thereof.

[0005] To achieve the above object, the present invention provides a method for preparing porous tubular graphite phase carbon nitride, comprising the following steps:

[0006] (1.1) Add acetic acid to the melamine aqueous solution, heat and stir to obtain a mixed solution;

[0007] (1.2) subjecting the mixed solution to a hydrothermal reaction, followed by filtering, and washing and drying the resulting filter residue to obtain a carbon nitride precursor;

[0008] (1.3) Grinding the carbon nitride precursor;

[0009] (1.4) The ground carbon nitride precursor is calcined to obtain the porous tubular graphite phase carbon nitride.

[0010] Furthermore, in step (1.1), the concentration of the melamine aqueous solution is 200 g / L, and the volume ratio of acetic acid to the melamine aqueous solution is 1 to 3:100.

[0011] Furthermore, in step (1.1), the temperature of the heating and stirring treatment is 55 to 65° C., and the time is 15 to 25 minutes.

[0012] Furthermore, in step (1.2), the hydrothermal reaction temperature is 120-180° C., and the time is 12-16 h.

[0013] Furthermore, in step (1.2), the drying temperature is 60 to 80°C.

[0014] Furthermore, in step (1.4), the calcination treatment process is as follows: in an air atmosphere, heating the temperature from room temperature to 500-600° C. at a heating rate of 2-4° C. / min for calcination for 3-5 hours.

[0015] The present invention also provides a method for preparing a single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst, comprising the following steps:

[0016] (2.1) Adding acetic acid to the melamine aqueous solution, heating and stirring to obtain a mixed solution;

[0017] (2.2) subjecting the mixed solution to a hydrothermal reaction, followed by filtering, and washing and drying the resulting filter residue to obtain a carbon nitride precursor;

[0018] (2.3) Mixing the carbon nitride precursor and the Mn-MOF, and grinding them to obtain a mixed powder;

[0019] (2.4) The mixed powder is calcined to obtain the single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst.

[0020] Furthermore, in step (2.1), the concentration of the melamine aqueous solution is 200 g / L, and the volume ratio of acetic acid to the melamine aqueous solution is 1 to 3:100.

[0021] Furthermore, in step (2.1), the temperature of the heating and stirring treatment is 55 to 65° C., and the time is 15 to 25 minutes.

[0022] Furthermore, in step (2.2), the hydrothermal reaction temperature is 120-180° C., and the time is 12-16 h.

[0023] Furthermore, in step (2.2), the drying temperature is 60 to 80°C.

[0024] Furthermore, in step (2.3), the mass ratio of Mn-MOF to carbon nitride precursor is 1 to 4:1000.

[0025] Furthermore, in step (2.3), the rotation speed of the grinding process is 400 to 600 rpm.

[0026] Furthermore, in step (2.4), the calcination treatment process is as follows: in an air atmosphere, heating the temperature from room temperature to 500-600° C. at a heating rate of 2-4° C. / min for calcination for 3-5 hours.

[0027] The present invention also provides a porous tubular graphite phase carbon nitride or a single-atom Mn-modified porous tubular graphite phase carbon nitride photocatalyst. The porous tubular graphite phase carbon nitride is prepared according to the above-mentioned preparation method of the porous tubular graphite phase carbon nitride, and the single-atom Mn-modified porous tubular graphite phase carbon nitride photocatalyst is prepared according to the above-mentioned single-atom Mn-modified porous tubular graphite phase carbon nitride photocatalyst.

[0028] The present invention also provides the use of the porous tubular graphite phase carbon nitride or the single-atom Mn-modified porous tubular graphite phase carbon nitride photocatalyst in photocatalytic degradation of antibiotic pollutants or photocatalytic hydrogen evolution.

[0029] The present invention prepares porous tubular graphite phase carbon nitride by combining acetic acid and melamine as a precursor, and then cracking the precursor through thermal polymerization to promote the exfoliation of the carbon nitride to form a tubular structure of graphite phase carbon nitride, thereby increasing the reaction active sites, effectively improving the catalytic activity of the graphite phase carbon nitride, and anchoring Mn atoms as sites, thereby improving the catalytic activity.

[0030] The present invention prepares a single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst by adding Mn-MOF during the thermal polymerization process of the porous tubular graphite-phase carbon nitride. This allows the Mn atoms in the MOF to enter the graphite-phase carbon nitride 3-s-triazine unit, thereby adding a new electron transfer pathway. At the same time, the cracking of the precursor is not affected, and a tubular-structured graphite-phase carbon nitride can still be formed. The introduction of Mn further enhances the catalytic activity.

[0031] The beneficial effects of the present invention are embodied in:

[0032] The porous tubular graphite phase carbon nitride prepared by the present invention has a larger specific surface area and provides more active sites compared with traditional block or sheet carbon nitride. The tubular structure has high mechanical strength and flexibility, and the structural stability and durability of the material are better under long-term use or high stress conditions. The tubular structure can increase the scattering and reflection of light, extend the propagation path of light inside the material, facilitate the rapid transmission of electrons, and reduce the recombination of electron-hole pairs.

[0033] The preparation process and operation method of the present invention are simple. A pre-assembly-thermal polymerization strategy is adopted to introduce single Mn atoms into the six-fold cavity of the graphite phase carbon nitride 3-s-triazine structure, which effectively improves the electron migration rate of the graphite phase carbon nitride. At the same time, a porous tubular graphite phase carbon nitride is constructed, so that the catalyst has more efficient photocatalytic degradation of antibiotic pollutants and decomposition of water to produce hydrogen.

[0034] The present invention selects Mn-doped porous tubular graphite phase carbon nitride, which has the advantages of low cost and low cost compared to precious metals. Compared with layered graphite phase carbon nitride, the present invention has a higher single atom loading capacity, a larger specific surface area, and more increased electron transfer pathways. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the SEM image of GCN prepared in Example 1.

[0036] Figure 2 This is an SEM image of the GCN prepared in Example 1 showing the porous structure.

[0037] Figure 3 This is the SEM image of Mn-GCN prepared in Example 2.

[0038] Figure 4 This is the SEM image of CN prepared in Comparative Example 1.

[0039] Figure 5 This is the SEM image of Mn,Co-GCN prepared in Comparative Example 2.

[0040] Figure 6 This is the test result of photocatalytic degradation of antibiotic pollutants by various materials (the negative segment of the horizontal axis in the figure is the dark box operation stage, and the positive segment is the photocatalytic reaction stage). DETAILED DESCRIPTION

[0041] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0042] Unless otherwise specified, the raw materials, reagents, or devices used below can be obtained from conventional commercial sources or by existing known methods. Unless otherwise specified, the methods used in the examples of the present invention are methods known to those skilled in the art. Mn-MOF was prepared by the following method: 0.156 g of manganese chloride tetrahydrate and 0.261 g of 1,3,5-benzenetricarboxylic acid were weighed and dissolved in 30 ml and 40 ml of NN dimethylacetamide solution, respectively. The mixture was ultrasonicated for five minutes and then stirred for 20 minutes. The mixture was transferred to a 100 ml reactor and hydrothermally treated at 140 ° C for 12 hours, then naturally cooled to room temperature. The resulting mixed solution was centrifuged, and the obtained solid was washed three times with dimethylacetamide and methanol, respectively, and then dried in a vacuum drying oven at 60 ° C for 12 hours. Finally, the solid was ground into a powder to obtain Mn-MOF.

[0043] Example 1

[0044] Preparation of porous tubular graphitic carbon nitride photocatalyst

[0045] (1.1) Add 1 ml of acetic acid to 100 ml of a 200 g / L melamine aqueous solution, sonicate for 5 min, and then stir at 60°C and 600 rpm for 20 min to obtain a mixture.

[0046] (1.2) The mixture was transferred to a stainless steel reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 180°C for 12 h. The mixture was cooled to room temperature and filtered. The resulting residue was washed with deionized water until neutral and dried at 60°C for 24 h to obtain an off-white solid, which was the carbon nitride precursor.

[0047] (1.3) Place the carbon nitride precursor in an agate mortar and grind at 500 rpm for 30 minutes.

[0048] (1.4) The ground carbon nitride precursor is placed in a muffle furnace and heated from room temperature to 550°C at a heating rate of 4°C / min in an air atmosphere. The mixture is calcined at 550°C for 4 h and then naturally cooled to room temperature to obtain porous tubular graphite carbon nitride, denoted as GCN.

[0049] Example 2

[0050] Preparation of Porous Tubular Graphitic Carbon Nitride Photocatalyst Modified by Single Mn Atoms

[0051] (2.1) Add 1 ml of acetic acid to 100 ml of a 200 g / L aqueous melamine solution, sonicate for 5 min, and then stir at 60°C and 600 rpm for 20 min to obtain a mixture.

[0052] (2.2) The mixture was transferred to a stainless steel reactor lined with polytetrafluoroethylene and hydrothermally reacted at 180°C for 12 h. The mixture was cooled to room temperature and filtered. The resulting residue was washed with deionized water until neutral and dried at 60°C for 24 h to obtain an off-white solid, which was the carbon nitride precursor. The carbon nitride precursor was placed in an agate mortar and ground at 500 rpm for 30 min for later use.

[0053] (2.3) Mix 5 g of the ground carbon nitride precursor with 10 mg of Mn-MOF in an agate mortar and grind at 400 rpm for 15 min to obtain a mixed powder.

[0054] (2.4) The mixed powder was placed in a muffle furnace and heated from room temperature to 550°C at a heating rate of 4°C / min in an air atmosphere and calcined at 550°C for 4 h. The mixed powder was then naturally cooled to room temperature to obtain a single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst, denoted as Mn-GCN.

[0055] Example 3

[0056] Preparation of Porous Tubular Graphitic Carbon Nitride Photocatalyst Modified by Single Mn Atoms

[0057] (2.1) Add 2 ml of acetic acid to 100 ml of a 200 g / L melamine aqueous solution, sonicate for 5 min, and then stir at 55°C and 600 rpm for 25 min to obtain a mixture.

[0058] (2.2) The mixture was transferred to a stainless steel reactor lined with polytetrafluoroethylene and hydrothermally reacted at 150°C for 14 h. The mixture was cooled to room temperature and filtered. The resulting residue was washed with deionized water until neutral and dried at 70°C for 24 h to obtain an off-white solid, which was the carbon nitride precursor. The carbon nitride precursor was placed in an agate mortar and ground at 500 rpm for 30 min for later use.

[0059] (2.3) Mix 5 g of the ground carbon nitride precursor with 5 mg of Mn-MOF in an agate mortar and grind at 500 rpm for 15 min to obtain a mixed powder.

[0060] (2.4) The mixed powder was placed in a muffle furnace and heated from room temperature to 600°C at a heating rate of 3°C / min in an air atmosphere and calcined at 600°C for 3 h. After that, it was naturally cooled to room temperature to obtain a single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst, which was recorded as Mn-GCN-2.

[0061] Example 4

[0062] Preparation of Porous Tubular Graphitic Carbon Nitride Photocatalyst Modified by Single Mn Atoms

[0063] (2.1) Add 3 ml of acetic acid to 100 ml of a 200 g / L aqueous melamine solution, sonicate for 5 min, and then stir at 65°C and 600 rpm for 15 min to obtain a mixture.

[0064] (2.2) The mixture was transferred to a stainless steel reactor lined with polytetrafluoroethylene and hydrothermally reacted at 120°C for 16 h. The mixture was cooled to room temperature and filtered. The resulting residue was washed with deionized water until neutral and dried at 80°C for 24 h to obtain an off-white solid, which was the carbon nitride precursor. The carbon nitride precursor was placed in an agate mortar and ground at 500 rpm for 30 min for later use.

[0065] (2.3) Mix 5 g of the ground carbon nitride precursor with 20 mg of Mn-MOF in an agate mortar and grind at 600 rpm for 15 min to obtain a mixed powder.

[0066] (2.4) The mixed powder was placed in a muffle furnace and heated from room temperature to 500°C at a heating rate of 5°C / min in an air atmosphere and calcined at 500°C for 5 h. The mixed powder was then naturally cooled to room temperature to obtain a single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst, designated as Mn-GCN-3.

[0067] Comparative Example 1

[0068] Preparation of graphite carbon nitride photocatalyst by traditional thermal polymerization

[0069] Take 100 ml of a 200 g / L melamine aqueous solution, ultrasonicate it for 5 minutes, then stir it at 60°C and 600 rpm for 20 minutes, then transfer it to a stainless steel reactor lined with polytetrafluoroethylene, hydrothermally react at 180°C for 12 hours, cool it to room temperature, and then filter it. The resulting filter residue is washed with deionized water until it is neutral, and then dried at 60°C for 24 hours to obtain a white solid, which is a carbon nitride precursor. The carbon nitride precursor is placed in an agate mortar and ground at 500 rpm for 30 minutes. Then, it is placed in a covered crucible and heated from room temperature to 550°C at a heating rate of 4°C / min and calcined at 550°C for 4 hours. Then, it is naturally cooled to room temperature to obtain graphite phase carbon nitride prepared by traditional thermal polymerization, recorded as CN.

[0070] Comparative Example 2

[0071] Preparation of graphitic carbon nitride photocatalyst modified with single-atom Mn by conventional thermal polymerization

[0072] In this comparative example, the catalyst was prepared according to the same method as in Example 2, except that the carbon nitride precursor in step (2.3) was replaced with the ground carbon nitride precursor obtained in Comparative Example 1. Finally, a conventional thermal polymerization method graphite phase carbon nitride photocatalyst modified with single-atom Mn was obtained, which was recorded as Mn-CN.

[0073] Comparative Example 3

[0074] Preparation of Porous Tubular Graphitic Carbon Nitride Photocatalyst Modified by Single Atoms of Mn and Co

[0075] (3.1) Add 2 ml of acetic acid to 100 ml of a 200 g / L melamine aqueous solution, sonicate for 5 min, and then stir at 55°C and 600 rpm for 25 min to obtain a mixture.

[0076] (3.2) The mixture was transferred to a stainless steel reactor lined with polytetrafluoroethylene and hydrothermally reacted at 150°C for 14 h. The mixture was cooled to room temperature and filtered. The resulting residue was washed with deionized water until neutral and dried at 70°C for 24 h to obtain an off-white solid, which was the carbon nitride precursor. The carbon nitride precursor was placed in an agate mortar and ground at 500 rpm for 30 min for later use.

[0077] (3.3) Mix 5 g of the ground carbon nitride precursor with 5 mg of Mn-MOF and 10 mg of cobalt nitrate in an agate mortar and grind at 500 rpm for 15 min to obtain a mixed powder.

[0078] (3.4) The mixed powder was placed in a muffle furnace and heated from room temperature to 600°C at a heating rate of 3°C / min in an air atmosphere and calcined at 600°C for 3 h. After that, it was naturally cooled to room temperature to obtain a single-atom Mn and Co modified porous tubular graphite-phase carbon nitride photocatalyst, denoted as Mn,Co-GCN.

[0079] Comparative Example 4

[0080] Preparation of comparative photocatalysts

[0081] In this comparative example, the catalyst was prepared according to the same method as in Example 2, except that the amount of Mn-MOF added in step (2.3) was replaced with 5 mg, thereby obtaining a single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst, which was recorded as Mn-GCN-4.

[0082] Comparative Example 5

[0083] Preparation of comparative photocatalysts

[0084] In this comparative example, the catalyst was prepared in the same manner as in Example 2, except that the amount of Mn-MOF added in step (2.3) was replaced with 20 mg, thereby obtaining a single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst, designated as Mn-GCN-5.

[0085] Comparative Example 6

[0086] Preparation of comparative photocatalysts

[0087] In this comparative example, a catalyst was prepared in the same manner as in Example 2, except that the amount of acetic acid added in step (2.1) was replaced with 2 ml, to obtain a single-atom Mn-modified porous tubular graphite carbon nitride photocatalyst, designated as Mn-GCN-6.

[0088] Comparative Example 7

[0089] Preparation of comparative photocatalysts

[0090] In this comparative example, a catalyst was prepared in the same manner as in Example 2, except that the amount of acetic acid added in step (2.1) was replaced with 3 ml, to obtain a single-atom Mn-modified porous tubular graphite carbon nitride photocatalyst, designated as Mn-GCN-7.

[0091] Experimental Example 1

[0092] Catalyst structure determination

[0093] In order to analyze the structure of porous tubular graphite carbon nitride, SEM image analysis was performed on the prepared porous tubular graphite carbon nitride GCN. At the same time, SEM image analysis was also performed on the prepared single-atom Mn-modified porous tubular graphite carbon nitride photocatalyst Mn-GCN, the graphite carbon nitride CN prepared by traditional thermal polymerization method, and the single-atom Mn, Co-modified porous tubular graphite carbon nitride photocatalyst Mn,Co-GCN. The results are shown in Figure 2. Figures 1 to 5 As shown in FIG. 1 , it can be seen that the conventional CN has a block structure, while the GCN and Mn-GCN of the present invention have a tubular structure.

[0094] In addition, the specific surface area and pore size of the catalysts were tested by N2 adsorption-desorption. The results showed that the BET specific surface areas of CN, GCN, Mn-GCN, and Mn,Co-GCN were 4.86 cm 3 g -1 、10.73cm 3 g -1 、54.37cm 3 g -1 、26.22cm 3 g -1 , the pore volumes are 0.04 cm 3 g -1 , 0.22cm 3 g -1 、0.47cm 3 g -1 , 0.29cm 3 g -1 cm 3 g -1 , indicating that tubular structured graphite phase carbon nitride and Mn atom doping can effectively increase the specific surface area of ​​carbon nitride and increase the number of pores.

[0095] In addition, the Mn content in the catalyst was determined by ICP-OES. The results are shown in Table 1, indicating that Mn-CN can support more metal single atoms.

[0096] Table 1 Results of determination of Mn content in catalysts by ICP-MS

[0097]

[0098] Experimental Example 2

[0099] Photocatalytic degradation of antibiotic pollutants test

[0100] Test method: Weigh 10 mg of catalyst sample and disperse it into 100 ml of 10 mg / L tetracycline solution. Stir in a dark box for 30 minutes to reach adsorption equilibrium. Then use a 300W xenon lamp (equipped with a 420nm filter) as the light source for light reaction (60 minutes). During the entire reaction process, 3 ml of sample is taken every 10 minutes, and the sample is centrifuged to obtain the supernatant. The pollutant concentration is measured using a spectrophotometer. Each experiment is repeated 3 times, and the average value and error bars are shown. The test results of CN, GCN, Mn-GCN, and Mn,Co-GCN are shown in Figure 2. Figure 6 As shown in the figure, it can be seen that Mn-GCN has the best photocatalytic degradation effect on tetracycline, followed by Mn,Co-GCN, GCN and CN. CN, GCN, Mn-GCN, Mn,Co-GCN, Mn-CN After 60 minutes of photoreaction, the tetracycline degradation efficiencies were 35%, 52%, 98%, 65% and 83%, respectively. The decrease in degradation efficiency of Mn,Co-GCN compared with Mn-GCN may be due to the collapse of the tubular structure caused by a large number of metal atoms, which reduces the reaction specific surface area. In addition, metal agglomeration may be formed, reducing the catalytic activity of metal single atoms.

[0101] The same test method was used to test the photocatalytic degradation of antibiotic pollutants by other catalysts prepared in opposite proportions. The results showed that the tetracycline degradation efficiencies of Mn-GCN-4, Mn-GCN-5, Mn-GCN-6 and Mn-GCN-7 were 72%, 62%, 75% and 64% respectively after 60 minutes of photoreaction, indicating that the content of acetic acid and Mn-MOF had a significant effect on the activity of the catalyst, and excessive addition of Mn-MOF and acetic acid may cause the collapse of the tubular structure.

[0102] The catalyst was subjected to the above-mentioned photocatalytic degradation test repeatedly, and the stability and repeatability of the sample were evaluated through cyclic experiments. The results showed that four tetracycline photocatalytic degradation tests were carried out using Mn-GCN, and the degradation efficiency of tetracycline in the four tests was 98.3%, 97.0%, 96.0%, and 94.2%, respectively, indicating that Mn-GCN has good cyclic stability. However, the degradation efficiency of GCN for tetracycline dropped to 32.7% in the second photocatalytic degradation test, which may be due to the collapse of the carbon nitride tubular structure in the first test. This shows that the stability of the carbon nitride tubular structure can be improved by adding Mn-MOF during the thermal polymerization of porous tubular graphite phase carbon nitride. In addition, the degradation efficiency of CN for tetracycline dropped to 20.3% in the second photocatalytic degradation test, and the degradation efficiency of Mn,Co-CN for tetracycline dropped to 46.8% in the second photocatalytic degradation test, and only 35.7% in the fourth photocatalytic degradation test.

[0103] Experimental Example 3

[0104] Photocatalytic hydrogen evolution reaction test

[0105] Test method: 10 mg of catalyst was dispersed in 50 ml of triethanolamine aqueous solution (concentration 10 wt%), and 3 wt% Pt was in situ deposited on the catalyst surface by the photodeposition method. Nitrogen was aerated for 15 minutes to remove oxygen from the solution. Then, a 300 W xenon lamp (equipped with a 420 nm filter) was used as the light source. A constant temperature (25 ° C) circulating water system was used to control the reaction temperature. Samples were taken every 1 hour, and the H2 content was detected by online gas chromatograph using a high-purity nitrogen carrier gas thermal conductivity detector (TCD).

[0106] The test results show that all samples can produce hydrogen, among which Mn-GCN has the highest H2 production rate of 14576.28 umol h -1 g -1 , almost CN (135.64 μmol h -1 g -1 ) is 107 times that of GCN, while the H2 production rate of GCN is 258.65 μmol h -1 g -1 The H2 production rate of Mn,Co-GCN is 3535.37 μmol h -1 g -1 The H2 production rate of Mn-CN is 2272.83 μmol h -1 g -1 .

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a porous tubular graphite-phase carbon nitride photocatalyst modified with single-atom Mn, characterized in that: The following steps are involved: (2.1) Adding acetic acid to the melamine aqueous solution, heating and stirring to obtain a mixed solution; The concentration of the melamine aqueous solution is 200 g / L, and the volume ratio of acetic acid to the melamine aqueous solution is 1:100; (2.2) subjecting the mixed solution to a hydrothermal reaction, followed by filtering, and washing and drying the resulting filter residue to obtain a carbon nitride precursor; (2.3) Mixing the carbon nitride precursor and the Mn-MOF, and grinding them to obtain a mixed powder; the mass ratio of the Mn-MOF to the carbon nitride precursor is 2:1000; (2.4) The mixed powder is calcined to obtain the single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst.

2. The method for preparing the porous tubular graphite-phase carbon nitride photocatalyst modified with single-atom Mn according to claim 1, wherein: In step (2.1), the temperature of the heating and stirring treatment is 55 to 65°C, and the time is 15 to 25 minutes.

3. The method for preparing the single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst according to claim 1, wherein: In step (2.2), the temperature of the hydrothermal reaction is 120-180°C, and the time is 12-16 hours.

4. The method for preparing the single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst according to claim 1, wherein: In step (2.4), the calcination treatment process is as follows: in an air atmosphere, heating the temperature from room temperature to 500-600°C at a heating rate of 2-4°C / min for calcination for 3-5 hours.

5. A porous tubular graphite-phase carbon nitride photocatalyst modified with single-atom Mn, characterized in that: Prepared according to the method according to any one of claims 1 to 4.

6. Use of the single-atom Mn-modified porous tubular graphite-phase carbon nitride photocatalyst according to claim 5 in photocatalytic degradation of antibiotic pollutants or photocatalytic hydrogen evolution.

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