Phosphate radical and carbon doped Z-type photocatalytic material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photocatalytic materials, and particularly discloses a phosphate radical and carbon doped Z-type photocatalytic material and a preparation method and application thereof.The preparation method comprises the following steps that LCN is prepared, specifically, Chinese redbud tree dead leaf powder and urea are fully mixed and then placed in a muffle furnace to be calcined, and LCN is obtained; the preparation of LCN / Ag3PO4 comprises the following steps: putting LCN into ultrapure water, adding silver nitrate, dropwise adding a Na3PO4 solution, stirring in a dark place, carrying out suction filtration and washing on the material, and finally carrying out freeze drying and collection to obtain the LCN / Ag3PO4. According to the phosphate radical and carbon doped Z-type photocatalytic material as well as the preparation method and the application thereof, ordered transmission of electrons on the interface of the Z-type composite material is induced through dual driving force formed by a carbon intermediate energy level and PO4 < 3->, so that the migration and separation efficiency of generated carriers can be remarkably improved, and the photocatalytic performance of the photocatalytic material is improved. And a certain theoretical support and experimental basis are provided for preparing a high-efficiency heterojunction photocatalytic material.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic materials, in particular to a Z-type photocatalytic material doped with phosphate and carbon, and a preparation method and application thereof. Background Art

[0002] Carbon doping can effectively drive the orderly transfer of photogenerated charge carriers in Z-scheme materials, but the performance improvement of heterojunction composites remains unsatisfactory. In 2013, Chen's group previously prepared a Z-scheme photocatalyst, Ag3PO4 / AgI, using an ion exchange method. Activity testing demonstrated a 96.9% degradation rate for methyl orange. The researchers found that the presence of elemental Ag on the catalyst surface during illumination acted as a carrier transport bridge, promoting the directional transport of electrons along the Z-scheme, increasing the rate of carrier separation and migration, and effectively boosting photocatalytic activity. Building on the success of elemental Ag as the driving force for Z-scheme materials, the team successfully prepared a Z-scheme visible-light-responsive catalyst, Ag3PO4 / Ag / SiC, in 2015 through co-deposition and in situ photoreduction, achieving a similar 97% degradation rate for methyl orange. Mechanistic investigations further confirmed that elemental Ag nanoparticles generated during the photocatalytic reaction acted as bridges for photogenerated charge transport, facilitating the transport of charge carriers along the Z-scheme, significantly improving separation efficiency and enhancing catalytic activity. Inspired by the above, we found that Ag3PO4 produces Ag in the reaction. 0 At the same time, the tetrahedral phosphate ion (PO4 3- ) can induce holes (h + ) are transported to the surface of Ag3PO4.

[0003] Therefore, the present invention adopts thermal copolymerization and ion exchange method to compound Ag3PO4 and carbon source doped graphite phase carbon nitride (LCN) to successfully prepare Z-type photocatalytic material LCN / Ag3PO4. After mechanism exploration, it is found that on the basis of carbon doping to form an intermediate energy level, the additional introduction of PO4 3- Can be used as h + Directional transfer driving force. At the carbon intermediate energy level and PO4 3- As a dual driver, the Z-shaped composite material further suppresses the disordered carrier transport caused by insufficient driving force. The prepared composite material was applied to the removal of antibiotics, and it was found that under visible light irradiation, the degradation rate of the difficult-to-degrade antibiotic ciprofloxacin (CIP) reached 100% in just 4 minutes. This degradation rate was significantly improved compared to the degradation rate of unmodified pure graphite carbon nitride (CN) (22%) and carbon-doped graphite carbon nitride (LCN) (28.5%), showing a significant improvement in catalytic activity.

[0004] The present invention is based on the carbon intermediate energy level and PO4 3-The dual driving force formed can significantly improve the migration and separation efficiency of generated carriers by inducing orderly electron transmission at the interface of Z-type composite materials, providing certain theoretical support and experimental basis for the preparation of high-efficiency heterojunction photocatalytic materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a Z-type photocatalytic material doped with phosphate and carbon, and its preparation method and application, through the carbon intermediate energy level and PO4 3- The dual driving force formed induces the orderly transmission of electrons at the interface of Z-type composite materials, which can significantly improve the migration and separation efficiency of generated carriers, and provide certain theoretical support and experimental basis for the preparation of high-efficiency heterojunction photocatalytic materials.

[0006] To achieve the above object, the present invention provides a method for preparing a phosphate- and carbon-doped Z-type photocatalytic material, comprising the following steps: Step 1, preparation of LCN, collecting dried redbud tree leaves and grinding them into powder, adding the redbud tree leaf powder and urea into an agate mortar and mixing thoroughly, transferring the mixture into a crucible and calcining it in a muffle furnace, after the calcination is completed and the furnace temperature drops to room temperature, collecting the sample and grinding it to obtain LCN; Step 2, preparation of LCN / Ag3PO4, place LCN in 50mL ultrapure water, ultrasonically disperse for 20 minutes, and then transfer to a magnetic stirrer. After adding silver nitrate with stirring, stir in the dark for 30 minutes, and then drop into the completely dissolved Na3PO4 solution. After the addition is completed, stir in the dark for 120 minutes. Then, the material is filtered and washed, and finally freeze-dried and collected to obtain LCN / Ag3PO4.

[0007] Preferably, in step 1, the calcination conditions are as follows: heating from room temperature to 80°C and maintaining for 1 hour, then heating to 550°C and maintaining for 2 hours, and the heating rate during the calcination process is 5°C / min.

[0008] Preferably, in step 2, the amount of LCN added is 0.2 g.

[0009] Preferably, in step 2, the amount of silver nitrate added is 0.85 g, 1.7 g, 3.4 g, or 5.1 g.

[0010] The present invention also provides a Z-type photocatalytic material doped with phosphate and carbon, which is prepared according to the preparation method described above.

[0011] The present invention also provides the application of a Z-type photocatalytic material doped with phosphate and carbon, which is applied to removing ciprofloxacin.

[0012] The advantages and beneficial effects of the present invention using the above-mentioned phosphate- and carbon-doped Z-type photocatalytic material and its preparation method and application are: 1. The present invention constructs a Z-type heterojunction LCN / AP by combining LCN and Ag3PO4. Under the induction of carbon intermediate energy level, the PSⅠ (LCN) VB is e - Orderly transfer, with PO4 3- Induced h + The ordered transfer forms a dual driving force, further enhancing the photocatalytic redox ability.

[0013] 2. The present invention proves that h + It is the main active species involved in the photocatalytic redox reaction. In addition, the SEM image results show that during the reaction process, the Ag element in the composite material is converted from the combined state to the + Converted to Ag 0 , building a bridge for the transfer of carriers and promoting the h + and e on PSⅡ(Ag3PO4)CB - Through the activity test, the degradation rate of 10ppm antibiotic CIP under light is as high as 100% in just 4 minutes. According to the experimental results of PL, DRS, EIS, EPR, etc., it can be proved that the Z-type composite material LCN / AP has a strong affinity with carbon intermediate energy level and PO4 3- Induced dual driving force, and Ag 0 The bridging effect of the photocatalytic degradation of CIP (Citric Inorganic Prototype) significantly improved the separation and migration rate of charge carriers and the utilization rate of visible light, thereby increasing the photocatalytic degradation activity of CIP by more than ten times. Furthermore, under the same testing conditions, the optimal material, LCN / AP-2, was subjected to five degradation cycles and still demonstrated high catalytic activity and structural stability.

[0014] 3. The present invention constructs a dual driving force based on silver phosphate and carbon intermediate energy levels to induce orderly carrier transfer in Z-type materials, providing a certain idea for solving the problem of insufficient spontaneous driving force.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Spectra of samples Ag3PO4, CN / AP and LCN / AP of the present invention, wherein a is the XRD spectrum and b is the FT-IR spectrum; Figure 2 is the X-ray photoelectron spectrum of the sample LCN / AP-2 of the present invention, wherein a is the full XPS element spectrum, b is C1s, c is Ag 3d, d is P 2p, e is N 1s, and f is O 1s; Figure 3TEM images and EDS spectra of the sample LCN / AP of the present invention, wherein a, b, and c are TEM images, d is the EDS spectrum, e is the element distribution image before antibiotic degradation, and f is the element distribution image after antibiotic degradation; Figure 4 These are performance test graphs of samples AP, CN, LCN, CN / AP, and LCN / AP against CIP, wherein a is the activity degradation graph and b is the stability test graph of sample LCN / AP-2. Figure 5 : These are the test spectra of samples AP, CN, LCN, CN / AP, and LCN / AP of the present invention, wherein a is the EIS spectra of AP, CN, LCN, CN / AP, and LCN / AP, b is the PL spectra of AP, CN / AP, and LCN / AP, c is the DRS spectra of AP, CN / AP, and LCN / AP, and d is the energy band gap spectrum of AP; Figure 6 is the electron paramagnetic resonance spectrum of the sample LCN / AP of the present invention under dark and light conditions; Figure 7 This is the electron spin resonance spectrum of the sample LCN / AP-2 of the present invention before and after 2 minutes of illumination, where a is BMPO / ·O 2- , b is DMPO / ·OH; Figure 8 This is the free radical capture spectrum of the sample LCN / Ag3PO4-2 of the present invention; Figure 9 These are the Mott-Schottky spectra and the mechanism diagram of photocatalytic degradation of antibiotic CIP of the present invention, wherein a is the Mott-Schottky spectra of samples LCN and Ag3PO4, and b is the mechanism diagram of photocatalytic degradation of antibiotic CIP by the composite material LCN / AP. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0018] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0019] Unless otherwise defined, the reagents, equipment and other materials used in the present invention are all commercially available.

[0020] Example 1 A method for preparing a phosphate- and carbon-doped Z-type photocatalytic material comprises the following steps: Step 1: Preparation of LCN.

[0021] Dried leaves of the redbud tree were collected and ground into a powder. The powder and urea were then added to an agate mortar and thoroughly mixed. The mixture was transferred to a crucible and calcined in a muffle furnace. The calcination conditions were as follows: the temperature was raised from room temperature to 80°C and held for 1 hour, then to 550°C and held for 2 hours, at a heating rate of 5°C / min. After calcination, the sample was collected and ground to produce LCN after the furnace temperature cooled to room temperature.

[0022] Step 2: Preparation of LCN / Ag3PO4.

[0023] Four portions of 0.2g LCN were weighed and placed in 50mL of ultrapure water. After ultrasonic dispersion for 20 minutes, the mixture was transferred to a magnetic stirrer. 0.85g, 1.7g, 3.4g, and 5.1g of silver nitrate were added with stirring, respectively. After stirring in the dark for 30 minutes, the completely dissolved Na3PO4 solution was added dropwise. After the addition was complete, stirring was continued in the dark for 120 minutes. The material was then filtered, washed, and finally freeze-dried and collected. These were designated LCN / AP-1, LCN / AP-2, LCN / AP-3, and LCN / AP-4.

[0024] The same method and dosage as above were used to add CN in an amount equal to that of LCN to prepare photocatalysts, which were named CN / AP-1, CN / AP-2, CN / AP-3, and CN / AP-4.

[0025] As a control group, the same method as above was used to prepare silver phosphate (Ag3PO4) without adding carbon nitride, which was named AP.

[0026] 1. Structure, morphology and composition of LCN / Ag3PO4.

[0027] The structure and chemical composition of the LCN / AP series composite materials were tested by characterization methods such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). First, XRD was used to determine the crystal structure of the LCN / AP composite material. Figure 1 As shown in Figure a, the composite materials CN / AP and LCN / AP completely retain the diffraction peaks of all crystal planes of Ag3PO4, but the diffraction peak at 27.6° belonging to the carbon nitride (002) crystal plane cannot be observed, which may be because the content of Ag3PO4 in the material is too high. To confirm that the structure of g-C3N4 is complete. Figure 1 As shown in b, the catalyst was analyzed by FT-IR spectrum. -1 The characteristic peak at 1200-1650 cm corresponds to the tri-s-triazine ring unit. -1The characteristic peaks at 1730-1130 cm correspond to the CN and C=N heterocyclic functional groups of g-C3N4. -1 The characteristic peak at 3100 to 3400 cm corresponds to the CN heterocycle. It is found that the intensity of this characteristic peak of the sample LCN is significantly stronger than that of CN, which may be due to the fact that g-C3N4 doped with dead leaves will produce more groups when calcined at a higher temperature. -1 The characteristic peak at the wavelength range is generated by NH stretching vibration. Ag3PO4 is located at 1010cm in the infrared spectrum. -1 and 558cm -1 The two diffraction peaks at are PO4 3- Characteristic peak at 1010cm -1 The diffraction peak at 558 cm is caused by POP stretching vibration, while the diffraction peak at 558 cm -1 The characteristic peak at is caused by the bending vibration of OPO. In addition, in the wavelength range of 3600 to 3300 cm -1 The characteristic peaks at π / μm (μm) were fully retained in both the CN / AP and LCN / AP composites, corresponding to the stretching vibrations of HO in water adsorbed on the g-C3N4 surface. This result confirms that the addition of Ag3PO4 does not disrupt the g-C3N4 framework. Therefore, these characterization results demonstrate the successful preparation of the composites.

[0028] In order to study the composition of LCN / AP and the chemical environment of each element, XPS was used to characterize the composite AP / LCN. Figure 2 Figure a is the complete elemental spectrum of the material, indicating that the AP / LCN-2 composite material is composed of five elements: C, N, O, P, and Ag. Figure 2 In the C1s spectrum in middle b, three diffraction peaks are observed at 288eV, 286.4eV, and 284.8eV, corresponding to CC / C=C, C-NHX, and NC=N, respectively. Figure 2 There are two obvious diffraction peaks in c, located at 412.08eV (Ag3d 5 / 2 ) and 405.38eV(Ag3d 3 / 2 ). Figure 2 The peak at 132.7 eV shown in d is P2p, which may correspond to PO4 3− P in 5+ . Figure 2 In the N1s spectrum of the middle e, three diffraction peaks can be observed at 404.3eV, 400.5eV and 398.6eV, corresponding to NHx, NC3 and CN=N respectively; Figure 2The two diffraction peaks observed in the O1s spectrum in Figure 5 are attributed to the PO and C=O functional groups, located at 531.98 eV and 530.28 eV, respectively. The XPS results indicate that the composite material is tightly bound together through a chemical reaction, rather than a simple physical mixture. Combined with XRD and FT-IR results, this confirms the successful preparation of the material.

[0029] The morphology and lattice structure of the composite material LCN / AP were characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (TEM). Figure 3 A and Figure 3 Figure b shows a TEM image of the LCN / AP material. Ag3PO4 particles are clearly visible, evenly distributed on the flaky g-C3N4 material. No Ag3PO4 nanoparticles agglomerate. This indicates that g-C3N4 can serve as an effective support material, providing sufficient active sites for Ag3PO4 particles and inhibiting their aggregation. Consequently, the heterogeneous interface formed by Ag3PO4 and g-C3N4 allows for enhanced interaction, thereby improving the composite's ability to degrade pollutants under visible light. Figure 3 The high-resolution TEM image in the middle c shows that the composite material has a clear crystalline structure, indicating that the composite material forms crystal defects under the introduction of carbon elements, making the material have good crystallinity. Through calculation, the lattice spacing is 0.327nm, proving that the composite material has more reaction adsorption sites and reactant molecules adsorbed. Figure 3 The EDS characterization results of the total element distribution spectrum of d show that the composite material LCN / AP is composed of C, N, O, P, and Ag elements, and is evenly distributed on the surface of g-C3N4. Figure 3 Zhongehe Figure 3 Figures f and b are the EDS spectra of LCN / AP before and after degradation of antibiotics. The orange color (Ag element) is significantly darkened, indicating that the composite material LCN / AP produces Ag element when degrading pollutants. Before degrading antibiotic CIP, Ag element exists in the form of Ag3PO4 compound, while during the degradation process, Ag + Oxidized to Ag 0 Combined with the characterization results of XRD, FT-IR and XPS, it can be proved that the material composite is successful.

[0030] 2. Removal performance of LCN / Ag3PO4 on ciprofloxacin In order to evaluate the removal performance of CN and Ag3PO4 materials and their composite materials in the antibiotic CIP, the multi-channel photocatalytic reaction system (Pfizer, Beijing) PCX-50CDiscover was used to test the degradation activity of antibiotic ciprofloxacin (CIP). Figure 4It can be observed that LCN has a better degradation performance for CIP than CN, proving that the construction of carbon intermediate energy levels can also improve the catalytic activity for antibiotic CIP. The degradation rate of LCN / AP reached 100% in just 4 minutes, which is significantly improved compared to the catalytic activity of monomeric CN, LCN, and Ag3PO4. In addition, to prove that the material is expected to be used in practical applications, the sample LCN / AP-2 with the best degradation performance was subjected to 5 degradation cycles under the same pollutant degradation conditions. Figure 4 The results of the b-activity cycle characterization showed that the pollutants could still be completely degraded in 4 minutes after the fifth cycle, proving that the composite material has good light stability and reusability.

[0031] To explore the catalytic mechanism of the composite material LCN / AP that significantly improves the degradation activity of antibiotic CIP, EIS, PL, DRS, EPR and other tests were conducted, and the band gaps of LCN and Ag3PO4 were calculated by DRS. The conduction band position was estimated by combining the Mott-Schottky curve, the specific band position was determined and a mechanism diagram was drawn. In order to test the charge transfer characteristics of the prepared material, Figure 5 Figure (a) shows the electrochemical impedance spectroscopy of CN, LCN, CN / AP, and LCN / AP samples. CN / AP exhibits a smaller resistance radius than CN and Ag3PO4, indicating that heterojunction construction can shorten the carrier migration path in the semiconductor, thereby increasing their migration and separation rates and reducing the recombination probability. The resistance radius of LCN / AP is much smaller than that of CN / AP, indicating that the introduction of carbon intermediate energy levels can enhance the charge transfer performance of heterojunction materials. Figure 5 Figure b shows the fluorescence absorption spectrum test (PL) of a series of materials. With a laser wavelength of 365 nm, the sample LCN / AP shows a lower fluorescence emission peak intensity than the sample CN / AP, proving that the introduction of carbon intermediate energy levels has suppressed the recombination of carriers. Figure 5 Figure c is the UV-visible diffuse reflectance spectra (DRS) of CN / AP and LCN / AP. CN has an absorption edge at around 480nm, while Ag3PO4 has a narrower absorption range, with an absorption edge appearing at around 530nm. The absorption range of the composite material LCN / Ag3PO4 is between that of CN and Ag3PO4. Although it has a certain red shift relative to CN, its light absorption capacity is enhanced. The Kubelka-Munk calculation formula based on UV-vis DRS spectra is used to confirm the band gap of the photocatalyst. Figure 5 The band gap of Ag3PO4 can be observed to be 2.38eV. Based on the above characterization and analysis, the construction of the heterojunction helps the material improve the charge migration and separation ability and reduce the carrier recombination rate. The introduction of carbon intermediate energy levels helps the carriers migrate more orderly, thereby improving the photocatalytic activity.

[0032] like Figure 6 The electron paramagnetic resonance (EPR) spectra of the samples are shown. All samples show a Lorentzian line centered at g=2.0034. This line originates from the unpaired electrons on the sp2 carbon atoms in the π-conjugated structure. Before and after illumination, the EPR signal of the LCN / Ag3PO4 sample is significantly higher than that of the other samples, proving that the recombination of g-C3N4 and Ag3PO4 produces a large number of unpaired electrons. This indicates that a high concentration of free radicals may exist in the samples. For this reason, Figure 7 The electron spin resonance (ESR) spectrum can characterize the main active species produced by the prepared photocatalytic material LCN / AP during the photocatalytic reaction. The principle of ESR is to use the corresponding free radical scavenger to detect the corresponding superoxide radical (•O 2- ) and hydroxyl radicals (•OH), such as Figure 7 A and Figure 7 As shown in b. In the comparison before and after illumination, the change of peak intensity can be clearly detected, which proves that •O 2- (a) and •OH (b), thus proving that the complexation of g-C3N4 and Ag3PO4 produces a large number of unpaired electrons, which react to generate •O 2- , •OH and other active species involved in redox.

[0033] In order to determine the active species involved in the photocatalytic degradation of pollutants, Figure 8 To conduct a capture experiment on the photocatalyst LCN / AP, 10 ppm CIP was degraded under visible light irradiation, and holes h were added respectively. + The scavenger EDTA-2Na, the superoxide radical scavenger 1.4-benzoquinone (BQ) and the hydroxyl radical scavenger isopropyl alcohol (IPA) were added. After adding IPA and BQ, the degradation rate was significantly reduced, indicating that •O 2- , •OH is the main active species in photocatalytic degradation, which is consistent with the ESR test results. The addition of EDTA-2Na caused the activity of the catalyst to drop from 100% to 24% after 4 minutes of illumination, indicating that h + It is the most important active species in composite materials.

[0034] Based on the above characterization, it can be proved that the migration path of photogenerated carriers in the composite material LCN / Ag3PO4 shows the orderly transfer characteristics of the Z-type mechanism. At the same time, combined with the results of the free radical capture experiment, the holes and electrons are the main active substances, indicating that PO4 3- Inducing the orderly transfer of h+. Therefore, the Z-type composite photocatalytic material is at the intermediate energy level and PO4 3-As a dual driving force, the disordered transfer of carriers in the material is further improved, significantly increasing the separation migration rate and reducing the recombination, generating more active species participating in the redox reaction, thereby enhancing the photocatalytic performance of antibiotic degradation.

[0035] The conduction band position of the semiconductor is estimated by recording the Mott-Schottky curve. Figure 9 In figure a, Ag3PO4 and LCN were tested at 800Hz at room temperature, and the VB positions were -0.50eV and 0.42eV respectively. Combined with the band gap results calculated by DRS above, the energy band positions of LCN and Ag3PO4 were determined, and the photocatalytic mechanism was obtained as follows: Figure 9 As shown in b. Through DRS, PL, photoelectrochemical tests and significant improvement in activity performance, it is proved that the electron transfer path of the composite material is Z-type. The SEM image results show that a large amount of Ag is generated during the photocatalytic process. 0 , so Ag 0 A cross-link bridge is constructed between the two semiconductors to promote the recombination of electrons on PSⅡ (Ag3PO4) CB and holes on PSⅠ (LCN) VB. At the same time, the carbon intermediate energy level induces the electrons with strong reducing ability on PSⅠ (LCN) VB to catalyze the reaction with the pollutant CIP, while PO4 3- Induced h on PSⅡ(Ag3PO4)VB + The orderly transfer and the generated •OH make the composite material have a strong oxidation ability, and the pollutants are quickly oxidized into carbon dioxide and water. Therefore, the Z-type composite material LCN / AP has a strong oxidation capacity at the intermediate energy level of carbon and PO4 3- Under the dual drive of - and h + The orderly transfer of Z-type heterojunction can be effectively suppressed, thereby effectively suppressing the disorder transfer caused by the spontaneous driving force of the Z-type heterojunction.

[0036] By combining LCN and Ag3PO4 to construct a Z-type heterojunction LCN / AP, the PSⅠ (LCN) VB is induced by the carbon intermediate energy level. - Orderly transfer, with PO4 3- Induced h + The ordered transfer forms a dual driving force, further improving the photocatalytic redox ability. The free radical capture experiment proves that h + It is the main active species involved in the photocatalytic redox reaction. In addition, the SEM image results show that during the reaction process, the Ag element in the composite material is converted from the combined state to the + Converted to Ag 0 , building a bridge for the transfer of carriers and promoting the h + and e on PSⅡ(Ag3PO4)CB -Through the activity test, the degradation rate of 10ppm antibiotic CIP under light is as high as 100% in just 4 minutes. According to the experimental results of PL, DRS, EIS, EPR, etc., it can be proved that the Z-type composite material LCN / AP has a strong affinity with carbon intermediate energy level and PO4 3- Induced dual driving force, and Ag 0 With the bridge, the carrier separation and migration rate and visible light utilization efficiency are significantly improved, thereby increasing the photocatalytic degradation activity of CIP pollutants by more than ten times. Furthermore, under the same testing conditions, the optimal material LCN / AP-2 was subjected to five degradation cycles and still demonstrated high catalytic activity stability and structural stability. This invention, based on the dual driving force of silver phosphate and carbon intermediate energy levels, induces the orderly transfer of carriers in Z-type materials, providing a solution to the problem of insufficient spontaneous driving force.

[0037] Therefore, the present invention adopts the above-mentioned phosphate and carbon doped Z-type photocatalytic material and its preparation method and application, through the carbon intermediate energy level and PO4 3- The dual driving force formed induces the orderly transmission of electrons at the interface of Z-type composite materials, which can significantly improve the migration and separation efficiency of generated carriers, and provide certain theoretical support and experimental basis for the preparation of high-efficiency heterojunction photocatalytic materials.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a Z-type photocatalytic material doped with phosphate and carbon, characterized in that: The steps include: Step 1, preparation of LCN: collecting dried leaves of the redbud tree and grinding them into powder, adding the redbud tree leaf powder and urea into an agate mortar and mixing thoroughly, transferring the mixture into a crucible and calcining it in a muffle furnace. After the calcination is completed, after the temperature in the furnace drops to room temperature, collecting the sample and grinding it to obtain LCN; Step 2, preparation of LCN / Ag3PO4: Place LCN in 50 mL of ultrapure water, ultrasonically disperse for 20 minutes, and then transfer to a magnetic stirrer. Add silver nitrate while stirring, stir in the dark for 30 minutes, and then drop into the completely dissolved Na3PO4 solution. After the addition is complete, stir in the dark for another 120 minutes. Then, filter and wash the material, and finally freeze-dry and collect it to obtain LCN / Ag3PO4.

2. The method for preparing the phosphate- and carbon-doped Z-type photocatalytic material according to claim 1, wherein: In step 1, the calcination conditions are as follows: heating from room temperature to 80°C and maintaining for 1 hour, then heating to 550°C and maintaining for 2 hours, with a heating rate of 5°C / min during the calcination process.

3. The method for preparing the phosphate- and carbon-doped Z-type photocatalytic material according to claim 1, wherein: In step 2, the amount of LCN added was 0.2 g.

4. The method for preparing the phosphate- and carbon-doped Z-type photocatalytic material according to claim 1, wherein: In step 2, the amount of silver nitrate added is 0.85 g, 1.7 g, 3.4 g, or 5.1 g.

5. Phosphate- and carbon-doped Z-type photocatalytic material, characterized by: It is prepared according to the preparation method according to any one of claims 1 to 4.

6. The use of the phosphate- and carbon-doped Z-type photocatalytic material according to claim 5, characterized in that: Used to remove ciprofloxacin.

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