Preparation method of heterojunction catalyst constructed by carboxyl-modified cobalt phthalocyanine and bismuth oxychloride

Abstract

The application belongs to the field of photocatalysis, and particularly relates to a preparation method of a carboxyl-modified phthalocyanine cobalt and bismuth oxychloride constructed heterojunction catalyst, which comprises the following steps: taking CoTcPc, Bi(NO3)3.5H2O and KCl with a molar ratio of 1-7:100:100; dissolving Bi(NO3)3.5H2O powder in a preset concentration of HNO3 solution, then adding CoTcPc, mixing uniformly to obtain solution A; wherein the molar ratio of Bi(NO3)3.5H2O to HNO3 is 1:20; dissolving KCl powder in a preset concentration of NaOH solution to obtain solution B; wherein the molar ratio of KCl to NaOH is 1:20; mixing solution A and solution B uniformly, adjusting the pH to neutral, then continuously stirring for 20-30 min, fully reacting to obtain solution C; transferring solution C into a reaction kettle, reacting at a preset temperature for a preset time, and naturally cooling to room temperature to obtain sample D; and washing and drying sample D to obtain CoTcPc / BiOCl heterojunction material. The CoTcPc / BiOCl heterojunction material prepared by the method can improve the degradation performance of typical antibiotics in water.

Description

Technical Field

[0001] This application belongs to the field of photocatalysis technology, and relates to a chemical material, particularly a method for preparing a heterojunction catalyst constructed from carboxyl-modified cobalt phthalocyanine and bismuth oxychloride. Background Technology

[0002] Antibiotics are widely used in medicine and aquaculture. However, due to limitations in the absorption and metabolism of antibiotics by humans and animals, 30%–90% of antibiotics are released into water systems. The presence of antibiotic residues in water poses a serious threat to ecosystems and human health. Among the many methods for antibiotic removal, photocatalysis is considered a very promising technology due to its cost-effectiveness, high efficiency, and environmental friendliness.

[0003] To improve the degradation performance of typical antibiotics in water, this application constructs a heterojunction by introducing a carboxyl-modified cobalt phthalocyanine photosensitizer and a bismuth oxychloride photocatalyst, providing a reference for the construction of future photocatalytic composite systems. Summary of the Invention

[0004] In view of this, embodiments of this application provide a method for preparing a heterojunction catalyst constructed from carboxyl-modified cobalt phthalocyanine and bismuth oxychloride, which is used to improve the degradation performance of typical antibiotics in water.

[0005] The embodiments of this application adopt the following technical solutions:

[0006] This application provides a method for preparing a heterojunction catalyst constructed from carboxyl-modified cobalt phthalocyanine and bismuth oxychloride, the method comprising the following steps:

[0007] Weigh out CoTcPc, Bi(NO3)3·5H2O, and KCl in a molar ratio of 1 to 7:100:100;

[0008] Bi(NO3)3·5H2O powder was dissolved in a HNO3 solution of a predetermined concentration, and then CoTcPc was added and mixed evenly to obtain solution A; wherein the molar ratio of Bi(NO3)3·5H2O to HNO3 was 1:20.

[0009] KCl powder was dissolved in a NaOH solution of a predetermined concentration to obtain solution B; wherein the molar ratio of KCl to NaOH was 1:20.

[0010] Mix solutions A and B thoroughly, adjust the pH to neutral, and then continue stirring for 20-30 minutes to allow the reaction to proceed fully, thus obtaining solution C.

[0011] Solution C was transferred to a reaction vessel, reacted at a preset temperature for a preset time, and then naturally cooled to room temperature to obtain sample D;

[0012] Sample D was washed and dried to obtain CoTcPc / BiOCl heterojunction material.

[0013] In one optional embodiment, the concentrations of both the preset concentration HNO3 solution and the preset concentration NaOH solution are 2 mol / L.

[0014] In one optional embodiment, Bi(NO3)3·5H2O powder is dissolved in HNO3 solution, and then CoTcPc is added and mixed evenly to obtain solution A, specifically including:

[0015] After adding CoTcPc, the mixture is dispersed evenly by sonication for 20-40 minutes to obtain solution A.

[0016] In one optional embodiment, the step of mixing solution A and solution B uniformly includes:

[0017] Stir solutions A and B separately until homogeneous. While continuously stirring solution B with a magnetic force, add solution A dropwise to solution B.

[0018] In one optional implementation, after solution A and solution B are mixed evenly, the pH is adjusted to neutral using a NaOH solution or an HNO3 solution of a preset concentration.

[0019] In one alternative implementation, the molar ratio of CoTcPc to Bi(NO3)3·5H2O is 5:100.

[0020] In one optional embodiment, after the solution C is transferred to the reaction vessel, the preset temperature is 140℃-180℃ and the preset time is 10-14 hours.

[0021] In one optional embodiment, sample D is washed and dried to obtain a CoTcPc / BiOCl heterojunction material, specifically including:

[0022] Sample D was washed several times with deionized water and anhydrous ethanol, and then dried at 60℃ for 12 hours to obtain CoTcPc / BiOCl heterojunction material.

[0023] In one alternative implementation, CoTcPc is prepared by the following steps:

[0024] Weigh out trimellitic anhydride, anhydrous cobalt chloride, urea, ammonium chloride and ammonium molybdate in a preparation ratio of 62.5:10.5:112.5:8.6:1, add them to a mortar and mix well;

[0025] After thorough grinding, the mixture was placed in a crucible and calcined in a forced-air drying oven at 220°C for 6 hours. The resulting solid substance M was then soaked in 1 mol / L hydrogen chloride solution for 10 hours.

[0026] After filtration, solid M was boiled in 1 mol / L NaOH for 30 min, then filtered again and dried to obtain the intermediate product tetraamide cobalt phthalocyanine.

[0027] Take a predetermined mass of tetraamide cobalt phthalocyanine, dissolve it in a first predetermined volume of 2 mol / L NaOH saturated NaCl solution, and then boil it in an oil bath at 110°C for 6 hours. During this period, deionized water is continuously added to keep the total volume of the solution in the first predetermined volume unchanged. After the reaction is completed, dilute the solution with deionized water to a second predetermined volume, let it stand for 1 hour, and then filter it.

[0028] The obtained filtrate was adjusted to a pH of about 2 with concentrated hydrochloric acid, and after standing for precipitation, the supernatant was discarded. The precipitate was washed several times with deionized water and methanol, dried in an oven at 60°C, and ground to obtain tetracarboxylated cobalt phthalocyanine.

[0029] The above-mentioned technical solutions adopted in the embodiments of this application can achieve the following beneficial effects: This application provides a method for preparing a heterojunction catalyst constructed by a carboxyl-modified cobalt phthalocyanine photosensitizer and bismuth oxychloride. The CoTcPc / BiOCl heterojunction material prepared by this method can improve the degradation performance of typical antibiotics in water and provide a reference for the construction of future photocatalytic composite systems. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 This is a main flow chart of a method for preparing a heterojunction catalyst constructed from carboxyl-modified cobalt phthalocyanine and bismuth oxychloride in the embodiments of this application;

[0032] Figure 2 This is a SEM image of CoTcPc / BiOCl 5% prepared according to the embodiments of this application at a resolution of 500 nm;

[0033] Figure 3 This is a TEM image of CoTcPc / BiOCl at 5% concentration;

[0034] Figure 4 It is a HRTEM image of CoTcPc / BiOCl 5%;

[0035] Figure 5 This is a diagram illustrating the mechanism of CTC degradation by CoTcPc / BiOCl at 5%. Detailed Implementation

[0036] As described in the background section, photocatalysis is considered a promising technology among various methods for removing antibiotics. BiOCl, with its excellent optical and chemical properties and low toxicity, has good application prospects. Its unique layered structure can effectively delay electron-hole recombination. However, BiOCl has a wide band gap and low utilization efficiency for visible light, and electron-hole recombination is very easy in the short term. Therefore, it is necessary to modify it to improve its performance. Compared to doping, induced oxygen vacancies, and morphology control strategies, which are subject to dosage limitations on doping amount and oxygen vacancy concentration, and are influenced by multiple factors in morphology preparation, constructing heterojunctions has greater application potential. In addition, CoPc, as a photosensitizer, has gradually attracted great attention. Due to its inherent properties, it can not only sensitize other materials and promote their excitation under visible light, but also generate reactive oxygen species to degrade pollutants. By constructing heterojunctions by combining CoPc and BiOCl to perform photocatalytic degradation of tetracycline antibiotics, CoPc can effectively sensitize BiOCl to broaden the photoresponse range and improve the photocatalytic activity of BiOCl. On the other hand, it can also solve the problems of low free radical production and slow degradation rate that occur when CoPc is used alone.

[0037] However, due to the large conjugated planar structure of phthalocyanines, they are prone to π-π conjugated aggregation, forming dimers or polymers in water. This masks their active sites, altering their physicochemical properties and reducing their dispersibility. Ultimately, this makes it difficult to further improve catalytic efficiency and may even reduce it. Therefore, it is necessary to further modify metal phthalocyanines to address the association problem. Ligand modification of metal phthalocyanines with substituents possessing different electron-donating and electron-withdrawing properties alters the electron density of the metal phthalocyanines, ultimately improving the degradation efficiency of the system.

[0038] Furthermore, unlike other modification methods, the introduction of substituents alters the photoelectric properties of phthalocyanines, thereby changing their catalytic activity. Both axial and peripheral substitutions affect the enhancement of the catalytic activity of metal phthalocyanines, but their mechanisms differ. From an electrochemical perspective, peripheral substituents, linked to the benzene ring, can change the intramolecular electronic structure and intermolecular arrangement, promoting charge transfer. When the two materials are combined, the efficiency of photogenerated electron transport is improved. Axial and perpendicular substitutions primarily affect the electrical properties of phthalocyanines by altering the internal electron cloud density. From an optical perspective, both peripheral and axial substitutions can effectively suppress the decay of excited states, further promoting the generation of more O2 by increasing the triplet quantum yield.

[0039] The type of substituent group affects the catalytic mechanism differently. Introducing electron-donating groups such as amino, hydroxyl, alkoxy, and amide groups consumes the positive charge of the metal center, increases the electron cloud density, causes a red shift in the Q band of the metal phthalocyanine in ultraviolet absorption, reduces the band gap, and improves light absorption. However, the probability of intersystem crossing to excite a triplet state is low, resulting in a lower O2 yield from the interaction between the triplet and ground states. Introducing electron-withdrawing groups such as cyano, sulfonic acid, acyl, and carboxyl groups increases the oxidation potential, causes a red shift in the Q band, and reduces the band gap. Furthermore, unlike electron-donating groups, they have a higher probability of intersystem crossing to excite a triplet state, leading to an increased O2 yield from the interaction between the triplet and ground states.

[0040] Based on the above considerations, researchers proposed a method for preparing a heterojunction catalyst by constructing a cobalt phthalocyanine photosensitizer modified with carboxyl group and bismuth oxychloride. The catalyst prepared by this method can achieve efficient degradation of new antibiotic pollutants in water through photocatalysis.

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0043] First refer to Figure 1 , Figure 1 This is a main flow chart of a method for preparing a heterojunction catalyst constructed from carboxyl-modified cobalt phthalocyanine and bismuth oxychloride, as described in the embodiments of this application. Figure 1 As shown, the preparation method of this application mainly includes the following steps:

[0044] S110: Weigh out CoTcPc, Bi(NO3)3·5H2O, and KCl in a molar ratio of 1 to 7:100:100;

[0045] S120: Dissolve Bi(NO3)3·5H2O powder in a HNO3 solution of a predetermined concentration, then add CoTcPc and mix thoroughly to obtain solution A; wherein, the molar ratio of Bi(NO3)3·5H2O to HNO3 is 1:20.

[0046] S130: Dissolve KCl powder in a NaOH solution of a predetermined concentration to obtain solution B; wherein the molar ratio of KCl to NaOH is 1:20;

[0047] S140: Mix solution A and solution B thoroughly, adjust the pH to neutral, and then continue stirring for 20-30 minutes to allow the reaction to proceed fully and obtain solution C.

[0048] S150: Transfer solution C to a reaction vessel, react at a preset temperature for a preset time, and then naturally cool to room temperature to obtain sample D;

[0049] S160: Wash and dry sample D to obtain CoTcPc / BiOCl heterojunction material.

[0050] In the above steps, the concentrations of both the preset concentration HNO3 solution and the preset concentration NaOH solution are 2 mol / L.

[0051] In step S110, the optimal molar ratio of CoTcPc (tetracarboxylated cobalt phthalocyanine) to Bi(NO3)3·5H2O is 5:100. In step S120, Bi(NO3)3·5H2O powder is dissolved in HNO3 solution, and then CoTcPc is added. The mixture can then be uniformly dispersed using ultrasonication (i.e., using ultrasound to mechanically vibrate the material to achieve uniform particle dispersion). For example, uniform dispersion can be achieved by ultrasonication for 20-40 minutes to obtain solution A.

[0052] In step S140, solutions A and B are stirred separately until homogeneous. While solution B is continuously stirred magnetically, solution A is added dropwise to solution B until they are thoroughly mixed. The pH of the mixed solution is then adjusted to neutral using either a pre-set concentration of NaOH solution or a pre-set concentration of HNO3 solution. The concentration of the HNO3 solution is the same as that used in step S120, both being 2 mol / L; the concentration of the NaOH solution is the same as that used in step S130, both being 2 mol / L.

[0053] In step S150, the preset temperature in the reactor can be 140℃-180℃, and the preset reaction time can be 10-14 hours.

[0054] In step S160, the specific steps include: washing sample D several times with deionized water and anhydrous ethanol, and drying it at 60°C for 12 hours to obtain CoTcPc / BiOCl heterojunction material.

[0055] The preparation method of this application will be further explained below with reference to a specific laboratory embodiment:

[0056] First, weigh 2 mmol (0.002 mol) of Bi(NO3)3·5H2O powder and dissolve it in 20 ml of 2 mol / L HNO3 solution. Then, add a certain molar ratio of CoTcPc (the molar ratio of CoTcPc to Bi(NO3)3·5H2O can be 1, 3, 5, or 7%; in this example, the molar ratio of CoTcPc to Bi(NO3)3·5H2O is 5%) and sonicate for 30 min to disperse evenly. This solution is labeled as solution A. Next, weigh 2 mmol (0.002 mol) of KCl powder and dissolve it in 20 ml of 2 mol / L NaOH solution. This solution is labeled as solution B.

[0057] Solutions A and B are stirred separately for a period of time to ensure uniform distribution. Then, under continuous magnetic stirring, solution A is added dropwise to solution B. After solutions A and B are completely mixed, the pH is adjusted to neutral using 2 mol / L NaOH solution or 2 mol / L HNO3 solution. The solution is then stirred for 20-30 minutes to allow for a complete reaction.

[0058] The reacted solution was transferred to a hydrothermal synthesis reactor and reacted at 160°C for 12 hours. After naturally cooling to room temperature, the obtained sample was washed several times with deionized water and anhydrous ethanol, and dried at 60°C for 12 hours to obtain a CoTcPc / BiOCl heterojunction material, denoted as CoTcPc / BiOCl 5%. Those skilled in the art will understand that if the molar ratio of CoTcPc to Bi(NO3)3·5H2O is 1%, 3%, or 7%, the resulting CoTcPc / BiOCl heterojunction materials will be denoted as CoTcPc / BiOCl 1%, CoTcPc / BiOCl 3%, and CoTcPc / BiOCl 7%. The optimal molar ratio of CoTcPc to Bi(NO3)3·5H2O is 5%, and the following explanation will use the CoTcPc / BiOCl 5% heterojunction material as an example.

[0059] The synthesized CoTcPc / BiOCl 5% photocatalyst demonstrates successful preparation of the heterojunction material based on structural morphology characterization. Furthermore, the sensitization process of the substituent-modified metal phthalocyanine did not significantly alter the BiOCl crystal structure. Photoelectrochemical property characterization indicates that the substituent-modified metal phthalocyanine effectively improves its photoelectrochemical properties, further enhancing the sensitized BiOCl's response in the visible light range and strengthening electron-hole separation. Photocatalytic activity experiments show that the degradation efficiency of CTC by BiOCl sensitized with the substituent-modified metal phthalocyanine is further improved. CoTcPc / BiOCl 5% still achieves a 94.7% CTC degradation efficiency after 90 min of illumination and maintains good structural activity stability.

[0060] Furthermore, by using CoTcPc / BiOCl 5% at 500-4000 cm⁻¹ -1 The FT-IR spectrum within the region shows that CoTcPc / BiOCl 5% is at 536 cm⁻¹. -1 845cm -1 The presence of BiOCl characteristic peaks at 600 to 1600 cm⁻¹ indicates the stretching of Bi-O bonds and the vibration of Bi-Cl bonds. -1 A series of characteristic peaks related to phthalocyanine framework vibrations are present, indicating the presence of both BiOCl and phthalocyanine structures in the CoTcPc / BiOCl 5% catalyst. The presence of characteristic peaks from BiOCl and CoTcPc in the CoTcPc / BiOCl 5% spectrum confirms the successful construction of the heterojunction. Furthermore, some absorption peaks in the FT-IR spectrum of CoTcPc / BiOCl 5% exhibit a certain degree of redshift, which is related to the inductive effect of the electron-withdrawing groups.

[0061] Figure 2 These are SEM images of the CoTcPc / BiOCl 5% prepared in this application at a resolution of 500 nm, used for morphological characterization and determination of elemental distribution. Figure 2 As shown, a large number of sheet-like BiOCl particles are distributed on CoTcPc, indicating that the CoTcPc / BiOCl 5% heterojunction material has been successfully synthesized. Further mapping and EDS tests on the two CoTcPc / BiOCl materials revealed that CoTcPc / BiOCl 5% contains six elements: C, N, O, Cl, Co, and Bi, further verifying the successful synthesis of CoTcPc / BiOCl 5%.

[0062] The morphology of CoTcPc / BiOCl 5% was observed using TEM, and the crystal structure was analyzed, such as... Figure 3 and 4 As shown, Figure 3 This is a TEM image of CoTcPc / BiOCl at 5%. Figure 4 This is a HRTEM image of CoTcPc / BiOCl at 5%. As can be seen from the image, at 200 nm, CoTcPc and BiOCl are tightly intercalated. Due to the magnetic properties of CoTcPc, BiOCl aggregates around it, forming a bond. Figure 4 The HRTEM image shows that the interplanar spacing d = 0.267 nm corresponds to the BiOCl crystal plane, proving that the CoTcPc / BiOCl 5% was successfully constructed.

[0063] The following reference Figure 5 , Figure 5 This is a diagram illustrating the degradation mechanism of CTC by CoTcPc / BiOCl at a 5% concentration. Figure 5As shown, CoTcPc exhibits strong visible light responsiveness and transforms into a singlet excited state upon initial illumination. Subsequently, the photosensitization process of BiOCl begins with the initial excitation of CoTcPc. Diffuse reflectance spectroscopy characterization confirms that after BiOCl is sensitized by CoTcPc, its light absorption extends into the visible spectral region, and the light absorption intensity further increases. After BiOCl is excited, electron-hole pair separation occurs, and then electrons excited to the LUMO band by CoTcPc are injected into the CB of BiOCl, reacting with adsorbed O2 to generate ·O2-, which can directly degrade organic matter.

[0064] The singlet excited state inside CoTcPc transforms into the triplet excited state, eventually generating O2. Theoretically, the introduction of the carboxyl group reduces the band gap, increases the probability of intersystem crossing to generate the triplet state, and thus increases the O2 yield generated by the interaction between the triplet state and the ground state.

[0065] In addition, h is generated on the VB of BiOCl. vb+ The flow towards the HOMO band of CoTcPc allows for direct oxidation of organic matter. Introducing CoTcPc further sensitizes and excites BiOCl, enhancing its activity and enabling electron-hole separation. Furthermore, the carboxyl-modified CoTcPc not only improves optical properties but also solves the solubility problem, resulting in a further enhancement of the catalyst's overall degradation activity.

[0066] In the preparation method of this application, the material CoTcPc can be prepared through the following steps:

[0067] Weigh out trimellitic anhydride, anhydrous cobalt chloride, urea, ammonium chloride and ammonium molybdate in a preparation ratio of 62.5:10.5:112.5:8.6:1, add them to a mortar and mix well;

[0068] After thorough grinding, the mixture was placed in a crucible and calcined in a forced-air drying oven at 220°C for 6 hours. The resulting solid substance M was then soaked in 1 mol / L hydrogen chloride solution for 10 hours.

[0069] After filtration, solid M was boiled in 1 mol / L NaOH for 30 min, then filtered again and dried to obtain the intermediate product tetraamide cobalt phthalocyanine.

[0070] Take a predetermined mass of tetraamide cobalt phthalocyanine, dissolve it in a first predetermined volume of 2 mol / L NaOH saturated NaCl solution, and then boil it in an oil bath at 110°C for 6 hours. During this period, deionized water is continuously added to keep the total volume of the solution in the first predetermined volume unchanged. After the reaction is completed, dilute the solution with deionized water to a second predetermined volume, let it stand for 1 hour, and then filter it.

[0071] The obtained filtrate was adjusted to a pH of about 2 with concentrated hydrochloric acid, and after standing for precipitation, the supernatant was discarded. The precipitate was washed several times with deionized water and methanol, dried in an oven at 60°C, and ground to obtain tetracarboxylated cobalt phthalocyanine.

[0072] In one specific embodiment: First, 26.90 g of 1,2,4-benzotriic anhydride (triphenyltriic anhydride), 4.55 g of anhydrous cobalt chloride (CoCl2), 48.37 g of urea (CO(NH2)2), 3.73 g of ammonium chloride (NH4Cl), and 0.43 g of ammonium molybdate ((NH4)2MoO4) were weighed and added to a mortar and mixed evenly. After thorough grinding, the mixture was placed in two 100 ml crucibles and calcined at 220 °C for 6 h in a forced-air drying oven. The obtained solid was soaked in 1 mol / L HCl for 10 h, filtered, and then boiled in 1 mol / L NaOH for 30 min. After further filtration, the solid was dried to obtain the intermediate product tetraamide cobalt phthalocyanine. 1 g of the intermediate product was then dissolved in 100 mL of a saturated NaCl solution of 2 mol / L NaOH. Boil at 110°C in an oil bath for 6 hours, continuously adding deionized water to maintain a constant total solution volume of 100 mL. After the reaction is complete, dilute the solution to 600 mL with deionized water, let it stand for 1 hour, and then filter. Adjust the pH of the filtrate to about 2 with concentrated hydrochloric acid, let it stand until the precipitate forms, discard the supernatant, wash the precipitate multiple times with deionized water and methanol, dry it in a 60°C oven, and grind it to obtain cobalt tetracarboxylated phthalocyanine.

[0073] The foregoing has described specific embodiments of this specification; other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than those in the embodiments and still achieve the desired results. Similar or identical parts between the various embodiments in this specification can be referred to mutually; each embodiment focuses on describing the differences from other embodiments.

[0074] The above description is merely an embodiment of this specification and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A method for preparing a heterojunction catalyst constructed from carboxyl-modified cobalt phthalocyanine and bismuth oxychloride, characterized in that, The method includes the following steps: Weigh out CoTcPc, Bi(NO3)3·5H2O, and KCl in a molar ratio of 1 to 7:100:100; Bi(NO3)3·5H2O powder was dissolved in HNO3 solution of a predetermined concentration, and then CoTcPc was added and mixed evenly to obtain solution A. The molar ratio of Bi(NO3)3·5H2O to HNO3 is 1:

20. KCl powder was dissolved in a NaOH solution of a predetermined concentration to obtain solution B; wherein the molar ratio of KCl to NaOH was 1:

20. Mix solutions A and B thoroughly, adjust the pH to neutral, and then continue stirring for 20-30 minutes to allow the reaction to proceed fully, thus obtaining solution C. Solution C was transferred to a reaction vessel, reacted at a preset temperature for a preset time, and then naturally cooled to room temperature to obtain sample D; Sample D was washed and dried to obtain a CoTcPc / BiOCl heterojunction material; Bi(NO3)3·5H2O powder is dissolved in HNO3 solution, and then CoTcPc is added and mixed evenly to obtain solution A, which specifically includes: After adding CoTcPc, the mixture was dispersed evenly by sonication for 20-40 minutes to obtain solution A; The steps to mix solution A and solution B thoroughly include: Stir solutions A and B separately until homogeneous. While continuously stirring solution B with a magnetic force, add solution A dropwise to solution B.

2. The method according to claim 1, characterized in that, The concentrations of both the preset concentration HNO3 solution and the preset concentration NaOH solution are 2 mol / L.

3. The method according to claim 1, characterized in that, After solutions A and B are mixed thoroughly, the pH is adjusted to neutral using a NaOH solution or an HNO3 solution of a preset concentration.

4. The method according to claim 1, characterized in that, The molar ratio of CoTcPc to Bi(NO3)3·5H2O is 5:

100.

5. The method according to claim 1, characterized in that, After transferring solution C to the reaction vessel, the preset temperature is 140℃-180℃, and the preset time is 10-14 hours.

6. The method according to any one of claims 1 to 5, characterized in that, Sample D was washed and dried to obtain the CoTcPc / BiOCl heterojunction material, specifically including: Sample D was washed several times with deionized water and anhydrous ethanol, and then dried at 60℃ for 12 hours to obtain CoTcPc / BiOCl heterojunction material.

7. The method according to claim 1, characterized in that, CoTcPc is prepared through the following steps: Weigh out trimellitic anhydride, anhydrous cobalt chloride, urea, ammonium chloride and ammonium molybdate in a mass ratio of 62.5:10.5:112.5:8.6:1, add them to a mortar and mix well; After thorough grinding, the mixture was placed in a crucible and calcined in a forced-air drying oven at 220°C for 6 hours. The resulting solid substance M was then soaked in 1 mol / L HCl for 10 hours. After filtration, solid M was boiled in 1 mol / L NaOH for 30 min, then filtered again and dried to obtain the intermediate product tetraamide cobalt phthalocyanine. Take a predetermined mass of tetraamide cobalt phthalocyanine, dissolve it in a first predetermined volume of 2 mol / L NaOH saturated NaCl solution, and then boil it in an oil bath at 110°C for 6 hours. During this period, deionized water is continuously added to keep the total volume of the solution in the first predetermined volume unchanged. After the reaction is completed, dilute the solution with deionized water to a second predetermined volume, let it stand for 1 hour, and then filter it. The obtained filtrate was adjusted to a pH of about 2 with concentrated hydrochloric acid, and after standing for precipitation, the supernatant was discarded. The precipitate was washed several times with deionized water and methanol, dried in an oven at 60°C, and ground to obtain tetracarboxylated cobalt phthalocyanine.

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