Preparation method of flower-shaped TP-BiOI heterojunction photocatalyst

Abstract

The invention discloses a preparation method of a flower-like polyimide-bismuth oxyiodide (TP-BiOI) heterojunction photocatalyst and efficient application of the flower-like polyimide-bismuth oxyiodide (TP-BiOI) heterojunction photocatalyst in the field of environmental pollutant removal, and belongs to the technical field of photocatalytic materials. The preparation method of the flower-like TP-BiOI heterojunction photocatalyst comprises the following steps: (1) performing solid-phase uniform grinding on an amine compound and an anhydride compound, and performing thermal polymerization to obtain a solid product TP; and (2) dissolving bismuth nitrate in a mixed solvent of ethylene glycol and water to obtain a solution I, adding TP with different mass ratios into the solution I, stirring at room temperature, adding a certain amount of KI, stirring, centrifuging, washing and drying to obtain the final TP-BiOI heterojunction photocatalyst. The heterojunction material belongs to a direct Z-type heterojunction, close contact between two semiconductors can ensure that an interface electric field is formed, due to the existence of the interface electric field, effective separation of photo-generated charges is achieved, and in addition, the heterojunction material has a unique flower-shaped structure, a high specific surface area and excellent visible light absorption performance, and can be applied to the field of light emitting devices. The method can play a continuous and efficient degradation role in the field of removal of environmental pollutants.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic materials, and more specifically relates to a preparation method of a flower-like TP-BiOI heterojunction photocatalyst. Background Art

[0002] Cr(VI) is one of the heavy metals that pose the greatest harm to the human body and the ecological environment, and has strong toxicity, persistence, and non-degradability, causing serious harm to both the human body and the ecological environment. Similarly, Rhodamine B (RhB) is widely used in the textile industry, cosmetics, and paper, and is a red organic cationic dye. However, RhB is a challenging organic substance that is not easily decomposed in the natural environment. Therefore, it gradually accumulates in water bodies to form dye wastewater, endangering the ecological environment. Currently, the treatment of heavy metal ions and dye pollution in water bodies has become an important research field. Photocatalysis is a green, environmentally friendly technology with mild reaction conditions, high catalytic activity, and selectivity, showing unique advantages in environmental treatment. The core of the photocatalysis technology is the photocatalyst. Designing a visible-light photocatalyst with long-wavelength response is crucial for water pollution treatment.

[0003] Polyimide (PI), as a special conjugated polymer engineering material, has been widely used in the fields of aerospace, microelectronics, and nanomaterials. PI is prepared by a simple green thermal polymerization reaction of an electron donor aromatic amine and an electron acceptor anhydride chain. By changing the structure of the comonomer and the condensation temperature, the band gap of PI can be adjusted within a large visible-light response range, making PI have strong structural tunability. However, its low specific surface area and rapid recombination of photo-generated charge carriers still result in medium photocatalytic efficiency. Therefore, how to improve the specific surface area and charge carrier separation efficiency of polyimide is the key to designing a photocatalyst. Bismuth-based compounds have attracted the attention of scientists due to their excellent visible-light absorption, energy band structure, and unique physical and chemical properties. Among them, BiOI has the strongest absorption in the visible-light region and a relatively narrow band gap, having a matching energy band structure with PI. It can be coupled with PI to form a direct Z-type heterojunction, aiming to improve the specific surface area of the photocatalyst and the separation efficiency of carriers. In this patent, polyimide is obtained by thermal polymerization of an amine compound and an anhydride compound, and then coupled with BiOI in a certain proportion to obtain a flower-like polyimide-bismuth oxyiodide heterojunction photocatalyst, and the removal effect on environmental pollutants is studied under visible light. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a flower-like TP-BiOI heterojunction photocatalyst, which has good visible-light response, a large specific surface area, and high separation efficiency of photo-generated carriers, and solves the problems of low specific surface area and easy recombination of photo-generated carriers existing in the commonly used polyimide photocatalyst.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: provides a preparation method of a flower-like TP-BiOI heterojunction photocatalyst, comprising the following steps:

[0007] (1) Solid-phase grinding and mixing of an amine compound and an acid anhydride compound are carried out uniformly, and then thermal polymerization is carried out to obtain a solid product TP;

[0008] (2) Bismuth nitrate is dissolved in a mixed solvent of ethylene glycol and water, denoted as solution one. Subsequently, TP with a mass ratio is added to solution one. After stirring at room temperature, KI is added, and then stirring, centrifugation, washing, and drying are carried out to obtain the final flower-like TP-BiOI heterojunction photocatalyst.

[0009] The present invention utilizes an amine compound and an acid anhydride compound to synthesize a polyimide material through thermal polymerization. Subsequently, it is coupled with BiOI, and the matching energy band structures of the two construct a direct Z-type heterojunction. The formed interfacial electric field can accelerate the effective separation of photogenerated charges. In addition, the flower-like structure of the heterojunction endows the material with the characteristic of a high specific surface area, which is beneficial to the adsorption of pollutants, and solves the problems of low specific surface area and easy recombination of photogenerated carriers existing in the commonly used polyimide photocatalysts.

[0010] The obtained flower-like TP polyimide-BiOI bismuth oxyiodide heterojunction photocatalyst of the present invention is recovered successively through the operation steps of centrifugation, washing, and drying, and the recovery method is simple.

[0011] Preferably, the amine compound includes one or more of tris(4-aminophenyl)amine, 1,3,5-tris(4-aminophenyl)benzene, and melem;

[0012] The acid anhydride compound includes one or more of pyromellitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and perylene-3,4,9,10-tetracarboxylic dianhydride.

[0013] Preferably, the molar ratio of the amine compound to the acid anhydride compound is 0.6 to 0.7.

[0014] More preferably, the mass ratio of the polyimide to BiOI is 0.35 to 0.55.

[0015] Preferably, the stirring temperature is room temperature, and the stirring time is 0.5 to 1 h;

[0016] The drying temperature in step (2) is 70 to 80 °C, and the drying time is 10 to 12 h.

[0017] Preferably, the washing step in step (2) is to wash the precipitate obtained after stirring and centrifugation, and the reagents used for washing are water and ethanol.

[0018] More preferably, the mixing in step (1) is grinding and mixing; the mixing time is 10 - 15 min.

[0019] Preferably, the temperature of the thermal polymerization is 300 - 325 °C, the heating rate of the thermal polymerization is 7 - 10 °C / min, and the time of the thermal polymerization is 3 - 5 h.

[0020] In one embodiment of the present invention, a flower-like polyimide-bismuth oxyiodide heterojunction photocatalyst prepared by the preparation method of a flower-like TP-BiOI heterojunction photocatalyst is provided.

[0021] In one embodiment of the present invention, an application of a flower-like TP-BiOI heterojunction photocatalyst in photocatalytic removal of environmental pollutants is provided.

[0022] The flower-like polyimide-bismuth oxyiodide heterojunction photocatalyst prepared by the present invention has a matched energy band structure between polyimide and bismuth oxyiodide. The close contact between the two can construct a direct Z-type heterojunction, improving the separation efficiency of charge carriers. Its flower-like structure is beneficial to the improvement of the specific surface area of the material, can better adsorb pollutants, and makes it suitable for photocatalytic removal of environmental pollutants. The flower-like polyimide-bismuth oxyiodide heterojunction photocatalyst prepared by the present invention can play a continuous and efficient degradation role in photocatalytic removal of environmental pollutants.

[0023] Based on the above technical solutions, the present invention discloses the following technical effects:

[0024] (1) The present invention synthesizes a flower-like polyimide-bismuth oxyiodide heterojunction photocatalyst by a simple thermal polymerization and room-temperature stirring method to solve the problems of low specific surface area and easy recombination of photo-generated electron-hole pairs existing in the commonly used polyimide photocatalysts. This synthesis method is simple, low-cost, and can be used for the synthesis of various polyimide-bismuth oxyiodide heterojunction photocatalysts with different structures according to the diversification of the selected monomer structure types.

[0025] (2) The existence of the direct Z-type heterojunction interface electric field formed by polyimide and BiOI in the flower-like polyimide-bismuth oxyiodide heterojunction photocatalyst obtained by the present invention can promote the effective separation of photo-generated charges. In addition, the flower-like structure can endow the material with the characteristic of high specific surface area, which is beneficial to the adsorption of pollutants, and solves the problems of low specific surface area and easy recombination of photo-generated carriers existing in the commonly used polyimide photocatalysts.

[0026] (3) The obtained flower-like polyimide-bismuth oxyiodide heterojunction photocatalyst of the present invention has a long service life and high stability, and can play a continuous and efficient degradation role in the field of photocatalytic removal of environmental pollutants. Description of the Drawings

[0027] Figure 1 SEM diagram of the photocatalyst described in Example 1;

[0028] Figure 2 XRD spectra of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2;

[0029] Figure 3 UV-Vis diffuse reflectance spectra of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2;

[0030] Figure 4 Infrared spectra of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2;

[0031] Figure 5 Fluorescence spectra of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2;

[0032] Figure 6 Nitrogen adsorption-desorption isotherm curves of the photocatalysts described in Example 1 and Comparative Example 1;

[0033] Figure 7 i-t curves of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2 under visible light irradiation;

[0034] Figure 8 EIS-Nyquist diagrams of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2 under visible light irradiation;

[0035] Figure 9 Schematic diagrams of the energy band structures of the photocatalysts described in Comparative Example 1 and Comparative Example 2;

[0036] Figure 10 Activity result diagrams of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2 for photocatalytic reduction of environmental pollutants (Cr(VI));

[0037] Figure 11 Stability result diagrams of the photocatalyst described in Example 1 for photocatalytic reduction of environmental pollutants (Cr(VI));

[0038] Figure 12 Activity result diagrams of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2 for photocatalytic degradation of environmental pollutants (Rhodamine B);

[0039] Figure 13The figure shows the stability results of the photocatalytic degradation of environmental pollutants (rhodamine B) by the photocatalyst described in Example 1. Detailed Description of the Invention

[0040] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation on the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0041] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0042] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0043] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the present invention specification are also obvious to those skilled in the art. The present invention specification and examples are merely exemplary.

[0044] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0045] Example 1

[0046] (1) Approximately 0.29 g of tris(4-aminophenyl)amine (TAPA) and 0.327 g of pyromellitic dianhydride (PMDA) were ground in an agate mortar until thoroughly mixed. The mixture was transferred to a covered crucible (semi-closed system) and heated to 300 °C at a rate of 10 °C / min for 4 h. The resulting black powder was labeled as TP.

[0047] (2) 0.97 g of Bi(NO 3 ) 3 ·5H2 O was dissolved in 15 mL of ethylene glycol, and then 15 mL of deionized water was added, denoted as Solution 1. The TP powder obtained in step (1) with a mass ratio of 45% (TP:BiOI = 45%) was added to Solution 1. The suspension was vigorously stirred at room temperature for 1 h, and then 0.33 g of KI was added. After the suspension was vigorously stirred for another 1 h, the product was collected by centrifugation, washed several times with water and ethanol, and dried at 65 °C for 12 h. The obtained powder was a flower-like TP-BiOI heterojunction photocatalyst, denoted as TP-BiOI(45%).

[0048] Example 2

[0049] (1) Approximately 0.35 g of 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 0.327 g of pyromellitic dianhydride (PMDA) were ground in an agate mortar until well mixed. The mixture was transferred to a covered crucible (semi-closed system) and heated to 300 °C at a rate of 10 °C / min for 4 h. The obtained powder was labeled as TPB.

[0050] (2) 0.97 g of Bi(NO 3 ) 3 ·5H 2 O was dissolved in 15 mL of ethylene glycol, and then 15 mL of deionized water was added, denoted as Solution 1. The TPB powder obtained in step (1) with a mass ratio of 45% (TPB:BiOI = 45%) was added to Solution 1. The suspension was vigorously stirred at room temperature for 1 h, and then 0.33 g of KI was added. After the suspension was vigorously stirred for another 1 h, the product was collected by centrifugation, washed several times with water and ethanol, and dried at 65 °C for 12 h. The obtained powder was a flower-like TPB-BiOI photocatalyst, denoted as TPB-BiOI(45%).

[0051] Example 3

[0052] (1) Approximately 0.22 g of melem and 0.327 g of pyromellitic dianhydride (PMDA) were ground in an agate mortar until well mixed. The mixture was transferred to a covered crucible (semi-closed system) and heated to 300 °C at a rate of 10 °C / min for 4 h. The obtained powder was labeled as PI.

[0053] (2) 0.97 g of Bi(NO 3 ) 3 ·5H 2O was dissolved in 15 mL of ethylene glycol, and then 15 mL of deionized water was added, denoted as Solution 1. The PI powder obtained in step (1) with a mass ratio of 45% (PI:BiOI = 45%) was added to Solution 1. The suspension was vigorously stirred at room temperature for 1 h, and then 0.33 g of KI was added. After the suspension was vigorously stirred for another 1 h, the product was collected by centrifugation, washed several times with water and ethanol, and dried at 65 °C for 12 h. The obtained powder was a flower-like PI-BiOI photocatalyst, denoted as PI-BiOI(45%).

[0054] Example 4

[0055] (1) Approximately 0.29 g of tris(4-aminophenyl)amine (TAPA) and 0.40 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) were ground in an agate mortar until evenly mixed. The mixture was transferred to a covered crucible (semi-closed system) and heated to 300 °C at a rate of 10 °C / min for 4 h. The obtained powder was labeled as TP-2.

[0056] (2) 0.97 g of Bi(NO 3 ) 3 ·5H 2 O was dissolved in 15 mL of ethylene glycol, and then 15 mL of deionized water was added, denoted as Solution 1. The TP-2 powder obtained in step (1) with a mass ratio of 45% (TP-2:BiOI = 45%) was added to Solution 1. The suspension was vigorously stirred at room temperature for 1 h, and then 0.33 g of KI was added. After the suspension was vigorously stirred for another 1 h, the product was collected by centrifugation, washed several times with water and ethanol, and dried at 65 °C for 12 h. The obtained powder was a flower-like TP-2 / BiOI heterojunction photocatalyst, denoted as TP-2 / BiOI(45%).

[0057] Example 5

[0058] (1) Approximately 0.29 g of tris(4-aminophenyl)amine (TAPA) and 0.588 g of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) were ground in an agate mortar until evenly mixed. The mixture was transferred to a covered crucible (semi-closed system) and heated to 300 °C at a rate of 10 °C / min for 4 h. The obtained powder was labeled as TP-3.

[0059] (2) 0.97 g of Bi(NO 3 ) 3 ·5H 2O was dissolved in 15 mL of ethylene glycol, and then 15 mL of deionized water was added, denoted as Solution 1. The TP-3 powder obtained in step (1) with a mass ratio of 45% (TP-3:BiOI = 45%) was added to Solution 1. The suspension was vigorously stirred at room temperature for 1 h, and then 0.33 g of KI was added. After the suspension was vigorously stirred for another 1 h, the product was collected by centrifugation, washed several times with water and ethanol, and dried at 65 °C for 12 h. The obtained powder was a flower-like TP-3 / BiOI heterojunction photocatalyst, denoted as TP-3 / BiOI(45%).

[0060] Comparative Example 1

[0061] Approximately 0.29 g of tris(4-aminophenyl)amine (TAPA) and 0.327 g of pyromellitic dianhydride (PMDA) were ground in an agate mortar until well mixed. The mixture was transferred to a covered crucible (semi-closed system) and heated to 300 °C at a rate of 10 °C / min for 4 h. The obtained black powder was labeled as TP.

[0062] Comparative Example 2

[0063] Take 0.97 g of Bi(NO 3 ) 3 ·5H 2 O, dissolve it in 15 mL of ethylene glycol, denoted as Solution 1. Take 0.33 g of KI and dissolve it in 15 mL of deionized water, denoted as Solution 2. Pour Solution 2 into Solution 1 and mix. The mixed solution was vigorously stirred at room temperature for 1 h, and then centrifuged. The red precipitate was collected, washed several times with water and ethanol, and dried at 65 °C for 12 h. The obtained red powder was denoted as BiOI.

[0064] Test Example

[0065] Performance tests were carried out on the flower-like TP-BiOI heterojunction photocatalyst (TP-BiOI(45%)) obtained in Example 1, the photocatalyst TP obtained in Comparative Example 1, and the photocatalyst BiOI obtained in Comparative Example 2. The test results are as Figures 1 to 13 shown.

[0066] The detection standards and detection methods for each performance are as follows:

[0067] X-ray diffraction (XRD) patterns were obtained on a Bruker AXSD8 Focus using filtered Cu Ka radiation Obtained. The UV-visible diffuse reflectance spectra were collected on a UV-2600 UV-vis spectrophotometer (Shimadzu). Fourier transform infrared (FT-IR) spectra were obtained using a Nicolet iS10 Fourier transform infrared spectrometer. Fluorescence spectra with an excitation wavelength of 300 nm were measured on a VARIAN Cary Eclipse spectrophotometer. Nitrogen adsorption-desorption isotherms were obtained using a Quanta-chrome Autosorb iQ apparatus at 77 K.

[0068] Electrochemical performance detection: Before the experiment, the samples were degassed under vacuum at 120 °C for 12 h. Electrochemical tests were carried out using a standard three-electrode system on a CHI6660E electrochemical workstation. An Ag / AgCl electrode, a Pt sheet, and the FTO conductive glass deposited with the sample were used as the reference electrode, counter electrode, and working electrode, respectively. The electrolyte solution was 0.2 M NaSO 4 aqueous solution. Preparation of the working electrode: 20 mg of the catalyst was dispersed in a centrifuge tube containing 2 mL of ethanol and 50 μL of perfluorosulfonic acid-polytetrafluoroethylene copolymer (Nafion) solution, and then ultrasonically dispersed evenly. The suspension was transferred to a 14 cm 2 FTO conductive glass using the spin coating method. The exposed area of the catalyst was 3 cm 2 . Finally, it was dried at room temperature to obtain the working electrode.

[0069] For the photocurrent test (i-t curve), a 300 W xenon lamp (CEL HXF300, AULIGHT) was used as the light source. To reduce the influence of experimental errors, the light source was irradiated from the back of the FTO glass substrate.

[0070] Using a CHI700E electrochemical workstation, in a 0.2 M NaSO 4 aqueous solution, at a voltage of -0.2 V, the electrochemical impedance spectroscopy (EIS) was tested at a frequency from 0.01 Hz to 10 kHz. The electrodes used for the EIS test were the same as those for the photocurrent test.

[0071] Figure 1 SEM image of the photocatalyst described in Example 1. Figure 2 XRD patterns of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2. Figure 3 UV-visible diffuse reflectance spectra of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2. Figure 4 Infrared spectra of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2. It can be Figures 1 - 4 seen that the flower-like TP-BiOI heterojunction photocatalyst was successfully prepared.

[0072] Figure 5Fluorescence spectra of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2. As can be seen from Figure 5 it, the fluorescence intensity of TP-BiOI(45%) shows a significant decreasing trend compared to TP, indicating that the radiative recombination of the flower-like TP-BiOI heterojunction photocatalyst is inhibited and the photogenerated carrier separation ability is enhanced.

[0073] Figure 6 Nitrogen adsorption-desorption isotherm curves of the photocatalysts described in Example 1 and Comparative Example 1. As can be seen from Figure 6 it, the nitrogen adsorption-desorption isotherm curve of TP-BiOI(45%) belongs to the type-IV isotherm curve with an H3 hysteresis loop, indicating that the flower-like TP-BiOI heterojunction photocatalyst is a mesoporous material formed by layered stacking and has a significantly increased specific surface area compared to TP.

[0074] Figure 7 i-t curves of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2 under visible light irradiation. Figure 8 EIS-Nyquist diagrams of the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2 under visible light irradiation. As can be seen from Figure 7 and 8 it, under visible light irradiation, the flower-like TP-BiOI heterojunction photocatalyst has a larger photocurrent density, indicating that the carrier separation performance of the photocatalyst has been greatly improved. In addition, the electrochemical impedance spectroscopy (EIS) further reveals the charge transfer characteristics of the samples. The experimental results show that the flower-like TP-BiOI heterojunction photocatalyst has a lower charge transfer resistance.

[0075] Figure 9 Energy band structure diagrams of the photocatalysts described in Comparative Example 1 and Comparative Example 2. As can be seen from Figure 9 it, the conduction bands (CB) of BiOI and TP are 0.19 eV and -1.39 eV respectively, and the valence bands (VB) of BiOI and TP are 2.06 eV and 0.75 eV respectively. The TP-BiOI heterojunction conforms to the charge transfer mechanism of the direct Z-scheme heterojunction.

[0076] Figure 10 Photocatalytic reduction activity results of Cr(VI) for the photocatalysts described in Example 1, Comparative Example 1, and Comparative Example 2. As can be seen from Figure 10 it, the flower-like TP-BiOI heterojunction photocatalyst obtained in the present invention has the highest Cr(VI) reduction activity, which is 2.3 times and 2.2 times that of TP and BiOI respectively.

[0077] Figure 11 Photocatalytic reduction stability results of Cr(VI) for the photocatalyst described in Example 1. As can be seen from Figure 11It can be seen that from the 4 consecutive photocatalytic reduction Cr(VI) experiments, the reduction efficiency of the flower-like TP-BiOI heterojunction photocatalyst obtained in the present invention only decreased slightly, which may be related to the loss of the catalyst during the recycling process.

[0078] Figure 12 It is the photocatalytic degradation activity result diagram of the photocatalysts described in Example 1, Comparative Example 1 and Comparative Example 2. From Figure 12 It can be seen that the flower-like TP-BiOI heterojunction photocatalyst obtained in the present invention has the highest degradation efficiency, which is 9.5 times and 3.4 times that of TP and BiOI respectively.

[0079] Figure 13 It is the photocatalytic degradation stability result diagram of the photocatalyst described in Example 1. From Figure 13 It can be seen that from the 4 consecutive photocatalytic degradation Rhodamine B experiments, the flower-like TP-BiOI heterojunction photocatalyst obtained in the present invention can still retain the same photocatalytic degradation ability as at the initial time.

[0080] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0081] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst, characterized in that: The steps include: (1) solid-phase grinding and mixing of an amine compound and an acid anhydride compound uniformly and then thermally polymerizing to obtain a solid product TP; (2) Dissolving bismuth nitrate in a mixed solvent of ethylene glycol and water, recorded as solution one, then adding TP in a mass ratio to solution one, stirring at room temperature and adding KI, stirring, centrifuging, washing, and drying to obtain the final flower-shaped TP-BiOI heterojunction photocatalyst.

2. The method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst according to claim 1, characterized in that: The amine compound includes one or more of tris(4-aminophenyl)amine, 1,3,5-tris(4-aminophenyl)benzene and melem; The acid anhydride compound includes one or more of pyromellitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic anhydride and perylene-3,4,9,10-tetracarboxylic dianhydride.

3. The method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst according to claim 1, characterized in that: The mass ratio of TP to BiOI is 0.35-0.

55.

4. The method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst according to claim 1, characterized in that: The washing step of step (2) is to wash the precipitate obtained after stirring and centrifuging, and the reagents used for the washing are water and ethanol.

5. The method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst according to claim 1, characterized in that: The molar ratio of the amine compound to the acid anhydride compound is 0.6 to 0.

7.

6. The method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst according to claim 1, characterized in that: The stirring time in step (2) is 0.5 to 1 h; The drying temperature in step (2) is 70-80° C. and the drying time is 10-12 hours.

7. The method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst according to claim 1, characterized in that: The mixing in step (1) is grinding mixing, and the mixing time is 10 to 15 minutes.

8. The method for preparing a flower-shaped TP-BiOI heterojunction photocatalyst according to claim 1, characterized in that: The temperature of the thermal polymerization is 300-325° C., the heating rate of the thermal polymerization is 7-10° C. / min, and the time of the thermal polymerization is 3-5 hours.

9. A flower-shaped TP-BiOI heterojunction photocatalyst, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of a flower-shaped TP-BiOI heterojunction photocatalyst as claimed in claim 9 in photocatalytic removal of environmental pollutants, characterized in that: Degrade organic pollutants under light.

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