AgBr / Co / NiBr2 composite catalyst and its preparation method and application

Abstract

The present invention discloses an AgBr / Co / NiBr2 composite catalyst, its preparation method, and application, belonging to the field of catalyst technology. The technical solution and preparation method include: 1) Preparation of NiBr2: Add nickel acetate to ethylene glycol solvent, stir, add KBr, and then add aqueous ammonia and stir to obtain NiBr2; 2) Preparation of the Co / NiBr2 composite material: Disperse NiBr2 in water, add cobalt nitrate, stir the reaction, centrifuge, wash, dry, calcine, and then place in a tube furnace for reduction with H2; 3) Preparation of the AgBr / Co / NiBr2 composite material: Disperse the Co / NiBr2 composite material in ethanol, add AgNO3 and KBr, stir, collect the solid product, and calcine to obtain the AgBr / Co / NiBr2 composite catalyst. The preparation method of the present invention is simple, low-cost, and has excellent catalytic performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and in particular relates to an AgBr / Co / NiBr2 composite material catalyst and a preparation method and application thereof. Background Art

[0002] With the annual increase in the emission of organic pollutants (such as toluene) in industrial wastewater, the development of efficient and stable photocatalytic materials has become a research hotspot in environmental remediation. Traditional photocatalytic materials (such as TiO2 and ZnO) suffer from low visible light utilization, high carrier recombination rates, and poor cyclic stability. In recent years, nickel-based oxides (such as NiO) have been used to modify photocatalysts due to their unique electronic structure. Chinese invention patent CN113441148A discloses a catalytic material for improving the biodegradability of petrochemical wastewater. The material comprises the following raw materials in the following weight ratio: 10-20 parts sludge powder, 5-10 parts Fe3O4, 1-2 parts bentonite, 1-2 parts a mixture of nickel oxide and copper oxide, 1-2 parts MnO2, and 0.2-0.5 parts ammonium bicarbonate. The preparation method is simple and easy to mass produce. It only needs to sinter the dehydrated and dried sludge with metals or metal oxides such as iron, manganese, copper and nickel at high temperature to obtain a porous composite material. The activation of biomass carbon and the loading of metal particles are achieved simultaneously during the cracking process, but its catalytic efficiency is still limited. Chinese invention patent CN111992008A discloses a method for catalytically enhancing the degradation of toluene by low-temperature plasma, which belongs to the technical field of catalytic degradation of toluene in organic waste gas. X A simple process involving the preparation of a / Al2O3 catalyst, commissioning of a low-temperature plasma reactor, catalytically enhanced low-temperature plasma degradation of toluene, and tail gas stripping achieves the degradation of toluene from organic waste gas. Prior research has explored the synergistic enhancement of photocatalytic performance through the construction of composite materials, but these preparation methods often involve complex templates or precious metal loading, resulting in cumbersome and costly processes. Summary of the Invention

[0003] The invention provides an AgBr / Co / NiBr2 composite material catalyst, a preparation method and application thereof. The preparation method is simple and low in cost, and the catalyst has good catalytic performance.

[0004] The technical solution of the present invention is:

[0005] In a first aspect, a method for preparing a AgBr / Co / NiBr2 composite catalyst is disclosed, comprising the following steps:

[0006] 1) Preparation of NiBr2: Add nickel acetate to ethylene glycol solvent and stir to form a transparent solution. Add KBr to the solution and stir until the KBr is completely dissolved. Then, add 4%-8% ammonia water to the mixed solution, stir at 20-30°C for 4-6 hours, dry at 60-70°C for 24-48 hours, and calcine at 500-600°C for 3-5 hours to obtain the product NiBr2.

[0007] 2) Preparation of Co / NiBr2 composite material: The NiBr2 product from step 1) was dispersed in water and uniformly dispersed by ultrasonication. Cobalt nitrate was added thereto and stirred for 30-40 minutes. The mixture was centrifuged and the precipitate was collected, washed, and dried. The precipitate was calcined in a muffle furnace and then reduced in a tubular furnace with H2 to obtain a Co / NiBr2 composite material. The particle size of the Co nanoparticles was 5-8 nm.

[0008] 3) Preparation of AgBr / Co / NiBr2 composite material: The Co / NiBr2 composite material was dispersed in ethanol and ultrasonically dispersed uniformly. AgNO3 was added thereto and stirred for 10-20 minutes. KBr was then added thereto. The mixture was placed in a water bath at 80-90°C to react until the ethanol was completely evaporated. The solid product was collected and calcined at 150-200°C for 3-6 hours to obtain an AgBr / Co / NiBr2 composite catalyst.

[0009] Preferably, in step 1), the mass volume ratio of nickel acetate, KBr and ethylene glycol is (3-5) g: (2.8-4.8) g: (25-30) mL.

[0010] Preferably, in step 1), the volume ratio of aqueous ammonia to ethylene glycol is 1:3-2:1.

[0011] Preferably, in step 2), the mass volume ratio of cobalt nitrate to water is (10-20) g: (30-50) mL.

[0012] Preferably, the drying in step 2) is oven drying at 60-70°C for 8-10 hours, the calcination temperature in step 2) is 200-300°C for 6-10 hours, and the H2 reduction temperature is 200-300°C for 4-5 hours.

[0013] Preferably, the reaction in step 2) is carried out in an N2 or Ar atmosphere.

[0014] Preferably, in step 3), the mass volume ratio of AgNO3, KBr and ethanol is (2-5) g: (1.4-3.5) g: (10-15) mL.

[0015] In the second aspect, the AgBr / Co / NiBr2 composite material catalyst prepared by the preparation method is disclosed.

[0016] In a third aspect, the application of the AgBr / Co / NiBr2 composite catalyst in photocatalytic degradation of toluene in wastewater is disclosed, comprising the following steps:

[0017] a) The prepared catalyst is placed in a quartz glass tube of a photoreactor. The photoreactor is set at a temperature of 20-30°C and a pressure of 0.1-0.3 MPa.

[0018] b) adding photocatalytic degradation wastewater into a quartz tube, sealing the quartz tube, and introducing helium into the liquid film photoreactor under dark conditions at a flow rate of 90-110 mL / min for a time of 20-40 min, and exhausting the gas in the reactor;

[0019] c) Under irradiation with a xenon lamp at a power of 300-400W, after 5-10 hours of reaction, measure the toluene concentration before and after the reaction.

[0020] An AgBr / Co / NiBr2 composite was successfully synthesized via a simple alcoholysis method. NiBr2 has a narrow band gap (~1.97 eV), and upon recombination with AgBr (band gap ~2.6 eV), its absorption range is broadened into the visible region. The energy bands of AgBr and NiBr2 are staggered, forming a stepped (Type-II) band structure. Under the action of an internal electric field, photogenerated electrons migrate from the conduction band of AgBr to that of NiBr2, while photogenerated holes migrate from the valence band of NiBr2 to that of AgBr, thereby suppressing the recombination of photogenerated carriers. Furthermore, Co acts as an electronic medium or bridge for charge transfer in the photocatalytic system, accelerating the transfer of photogenerated electrons from AgBr to Co to NiBr2 and further improving charge separation efficiency. Furthermore, the localized surface plasmon resonance (LSPR) of the Co nanoparticles generates a strong electromagnetic field in the visible region (particularly in the 500-700 nm range), significantly enhancing the composite's light absorption. Therefore, the enhanced photodegradation activity is attributed to the formation of Type-Ⅱ heterojunction, the electronic bridge of Co nanoparticles and their induced LSPR synergistic effect.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. This invention demonstrates highly efficient photocatalytic performance. The AgBr / Co / NiBr2 composite material, prepared via a three-step process, forms a heterojunction structure (AgBr and NiBr2) and, through the synergistic effect of Co nanoparticles, significantly enhances the visible light absorption range (400-800nm) and the efficiency of photogenerated carrier separation. Experiments have shown that this material can degrade toluene by up to 90% under xenon lamp irradiation.

[0023] 2. The present invention optimizes the preparation process and reduces production costs. The ethylene glycol solvent and ammonia precipitation method simplify the NiBr2 synthesis steps and avoid high temperature and high pressure conditions; the H2 reduction method accurately controls the Co nanoparticle loading and reduces the amount of precious metals used; the ethanol evaporation method achieves uniform AgBr coating and avoids complex post-processing.

[0024] 3. It maintains high activity under low temperature (20-30°C) and low pressure (0.1-0.3MPa) conditions and is suitable for low-concentration industrial wastewater treatment scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a morphology diagram of the catalyst prepared in Example 1 of the present invention.

[0026] Figure 2 This is a morphology picture of the catalyst prepared in Example 1 of the present invention under a high-power microscope.

[0027] Figure 3 is the XRD pattern of the catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0029] Example 1

[0030] The AgBr / Co / NiBr2 composite catalyst comprises a NiBr2 nanoflower carrier, loaded Co nanoparticles and AgBr, wherein the Co loading amount is 5wt% of the total mass of the catalyst, and the AgBr loading amount is 2wt% of the total mass of the catalyst.

[0031] The preparation method of the AgBr / Co / NiBr2 composite material catalyst comprises the following steps:

[0032] 1) Preparation of NiBr2: Add 5 g of nickel acetate to 30 mL of ethylene glycol solvent and stir to form a transparent solution. Add 4.8 g of KBr to the solution and stir until the KBr is completely dissolved. Then, add 56 mL of 7% aqueous ammonia to the mixed solution. Stir at 30°C for 4 h, dry at 60°C for 48 h, and calcine at 500°C for 5 h to obtain the product NiBr2.

[0033] 2) Preparation of Co / NiBr2 composite material: The NiBr2 product from step 1) was dispersed in 50 mL of water and uniformly dispersed by ultrasonication. 20 g of cobalt nitrate was added thereto and the mixture was stirred in a nitrogen atmosphere for 35 min. The mixture was centrifuged and the precipitate was collected and washed three times with deionized water. The mixture was oven-dried at 65°C for 9 h, calcined in a muffle furnace at 250°C for 8 h, and then reduced in a tubular furnace with hydrogen at 280°C for 4 h to obtain a Co / NiBr2 composite material with a particle size of 7 nm for the Co nanoparticles.

[0034] 3) Preparation of AgBr / Co / NiBr2 composite material: The above-mentioned Co / NiBr2 composite material was dispersed in 12 mL of ethanol and dispersed evenly by ultrasonication. 3 g of AgNO3 was added and stirred for 15 min. 2 g of KBr was then added and the mixture was placed in an 85°C water bath to react until the ethanol was completely evaporated. The solid product was collected and calcined at 180°C for 4 h to obtain the AgBr / Co / NiBr2 composite catalyst. The morphology of the catalyst is shown in FIG. Figure 1 and Figure 2 As shown, the XRD pattern is Figure 3 As shown; Figure 1 The display material is in the shape of nanoflowers. Figure 2 The particle distribution of Co and the coating of AgBr are shown under medium and high magnification microscope. Figure 3 The XRD pattern shows the existence of three phases: AgBr, Co and NiBr2.

[0035] The application of the AgBr / Co / NiBr2 composite catalyst in photocatalytic degradation of toluene in wastewater comprises the following steps:

[0036] a) 1 g of the prepared catalyst was placed in a quartz glass tube of a photoreactor. The photoreactor was set at a temperature of 25°C and a pressure of 0.2 MPa.

[0037] b) adding photocatalytic degradation wastewater into a sealed quartz tube, and introducing helium into the liquid film photoreactor under dark conditions at a flow rate of 100 mL / min for 30 min, and exhausting the gas in the reactor;

[0038] c) Under irradiation with a xenon lamp of 350 W, after 8 h of reaction, measure the toluene concentration before and after the reaction.

[0039] Example 2

[0040] The AgBr / Co / NiBr2 composite catalyst comprises a NiBr2 nanoflower carrier, loaded Co nanoparticles and AgBr, wherein the Co loading amount is 7wt% of the total mass of the catalyst, and the AgBr loading amount is 5wt% of the total mass of the catalyst.

[0041] The preparation method of the AgBr / Co / NiBr2 composite material catalyst comprises the following steps:

[0042] 1) Preparation of NiBr2: Add 3 g of nickel acetate to 25 mL of ethylene glycol solvent and stir to form a transparent solution. Add 3 g of KBr to the solution and stir until the KBr is completely dissolved. Then, add 25 mL of 4% aqueous ammonia to the mixed solution. Stir at 20°C for 5 h, dry at 65°C for 30 h, and calcine at 550°C for 4 h to obtain the product NiBr2.

[0043] 2) Preparation of Co / NiBr2 composite material: The NiBr2 product from step 1) was dispersed in 30 mL of water and uniformly dispersed by ultrasonication. 10 g of cobalt nitrate was added thereto and the mixture was stirred in an Ar atmosphere for 30 min. The mixture was centrifuged and the precipitate was collected and washed with deionized water three times. The precipitate was dried in a 60°C oven for 10 h, calcined in a muffle furnace at 200°C for 10 h, and then reduced in a tubular furnace with H2 at 200°C for 5 h to obtain a Co / NiBr2 composite material with a particle size of 5 nm for Co nanoparticles.

[0044] 3) Preparation of AgBr / Co / NiBr2 composite material: The above-mentioned Co / NiBr2 composite material was dispersed in 10 mL of ethanol and evenly dispersed by ultrasonication. 2 g of AgNO3 was added thereto and stirred for 10 min. Then, 1.4 g of KBr was added thereto. The mixture was placed in a 90°C water bath and reacted until the ethanol was completely evaporated. The solid product was collected and calcined at 150°C for 6 h to obtain an AgBr / Co / NiBr2 composite catalyst.

[0045] The application of the AgBr / Co / NiBr2 composite catalyst in photocatalytic degradation of toluene in wastewater comprises the following steps:

[0046] a) 1 g of the prepared catalyst was placed in a quartz glass tube of a photoreactor. The photoreactor was set at a temperature of 20°C and a pressure of 0.1 MPa.

[0047] b) adding photocatalytic degradation wastewater into a sealed quartz tube, and introducing helium into the liquid film photoreactor under dark conditions at a flow rate of 90 mL / min for 40 min, and exhausting the gas in the reactor;

[0048] c) Under irradiation with a xenon lamp at a power of 300 W, after 10 hours of reaction, measure the toluene concentration before and after the reaction.

[0049] Example 3

[0050] The AgBr / Co / NiBr2 composite catalyst comprises a NiBr2 nanoflower carrier, loaded Co nanoparticles and AgBr, wherein the Co loading amount is 10wt% of the total mass of the catalyst and the AgBr loading amount is 6wt% of the total mass of the catalyst.

[0051] The preparation method of the AgBr / Co / NiBr2 composite material catalyst comprises the following steps:

[0052] 1) Preparation of NiBr2: Add 4 g of nickel acetate to 30 mL of ethylene glycol solvent and stir to form a transparent solution. Add 3.8 g of KBr to the solution and stir until the KBr is completely dissolved. Then, add 10 mL of 8% aqueous ammonia to the mixed solution. Stir at 25°C for 6 h, dry at 70°C for 24 h, and calcine at 600°C for 3 h to obtain the product NiBr2.

[0053] 2) Preparation of Co / NiBr2 composite material: The NiBr2 product from step 1) was dispersed in 35 mL of water and uniformly dispersed by ultrasonication. 12.5 g of cobalt nitrate was added thereto and the mixture was stirred in an Ar atmosphere for 40 min. The mixture was centrifuged and the precipitate was collected and washed three times with deionized water. The precipitate was oven-dried at 70°C for 8 h, calcined in a muffle furnace at 300°C for 6 h, and then reduced in a tubular furnace with H2 at 300°C for 4.5 h to obtain a Co / NiBr2 composite material with Co nanoparticles having a particle size of 8 nm.

[0054] 3) Preparation of AgBr / Co / NiBr2 composite material: The above-mentioned Co / NiBr2 composite material was dispersed in 15 mL of ethanol and evenly dispersed by ultrasonication. 5 g of AgNO3 was added thereto and stirred for 10 min. Then, 3.5 g of KBr was added thereto. The mixture was placed in an 80°C water bath and reacted until the ethanol was completely evaporated. The solid product was collected and calcined at 200°C for 5 h to obtain an AgBr / Co / NiBr2 composite catalyst.

[0055] The application of the AgBr / Co / NiBr2 composite catalyst in photocatalytic degradation of toluene in wastewater comprises the following steps:

[0056] a) 1 g of the prepared catalyst was placed in a quartz glass tube of a photoreactor. The photoreactor was set at a temperature of 30°C and a pressure of 0.3 MPa.

[0057] b) adding photocatalytic degradation wastewater into a sealed quartz tube, and introducing helium into the liquid film photoreactor under dark conditions at a flow rate of 110 mL / min for 20 min, and exhausting the gas in the reactor;

[0058] c) Under irradiation with a xenon lamp of 350 W, after 5 h of reaction, measure the toluene concentration before and after the reaction.

[0059] Comparative Example 1

[0060] Different from Example 1, in this comparative example, only NiBr2 was prepared without loading Co and AgBr.

[0061] Comparative Example 2

[0062] Different from Example 1, in this comparative example, only the Co / NiBr2 composite material was prepared without loading AgBr.

[0063] Comparative Example 3

[0064] Different from Example 1, this comparative example prepares AgBr / NiBr2 by the following method:

[0065] 1) Preparation of NiBr2: Add 5 g of nickel acetate to 30 mL of ethylene glycol solvent and stir to form a transparent solution. Add 4.8 g of KBr to the above solution and stir until the KBr is completely dissolved. Then, add 56 mL of 7% aqueous ammonia to the above mixed solution. Stir at 30°C for 4 h, dry at 60°C for 48 h, and calcine at 500°C for 5 h to obtain the product NiBr2.

[0066] 2) Preparation of AgBr / NiBr2 composite material: The above-mentioned NiBr2 was dispersed in 12 mL of ethanol and evenly dispersed by ultrasonication. 3 g of AgNO3 was added thereto and stirred for 15 min. Then, 2 g of KBr was added thereto. The mixture was placed in an 85°C water bath and reacted until the ethanol was completely evaporated. The solid product was collected and calcined at 250°C for 4 h to obtain an AgBr / NiBr2 composite catalyst.

[0067] Comparative Example 4

[0068] The difference from Example 1 is that concentrated ammonia water with a mass concentration of 25% is added in this comparative example, and the rest of the preparation method and steps are the same as those in Example 1.

[0069] Comparative Example 5

[0070] The difference from Example 1 is that in step 2) of this comparative example, the loading is carried out in air, and the remaining preparation methods and steps are the same as those in Example 1.

[0071] Comparative Example 6

[0072] The difference from Example 1 is that the amount of silver nitrate added in step 3) of this comparative example is 5.2 g, and the rest of the preparation method and steps are the same as those of Example 1.

[0073] Comparative Example 7

[0074] The preparation method of the composite catalyst comprises the following steps:

[0075] 1) Preparation of NiBr2: Add 5 g of nickel acetate to 30 mL of ethylene glycol solvent and stir to form a transparent solution. Add 4.8 g of KBr to the above solution and stir until the KBr is completely dissolved. Then, add 56 mL of 7% aqueous ammonia to the above mixed solution. Stir at 30°C for 4 h, dry at 60°C for 48 h, and calcine at 500°C for 5 h to obtain the product NiBr2.

[0076] 2) Preparation of AgBr / NiBr2 composite material: The NiBr2 composite material was dispersed in 12 mL of ethanol and uniformly dispersed by ultrasonication. 3 g of AgNO3 was added thereto and stirred for 15 min. Then, 2 g of KBr was added thereto. The mixture was placed in an 85°C water bath and reacted until the ethanol was completely evaporated. The solid product was collected and calcined at 180°C to obtain an AgBr / NiBr2 composite catalyst.

[0077] 3) Preparation of Co / AgBr / NiBr2 composite material: The product of step 2) was dispersed in 50 mL of water and evenly dispersed by ultrasonication. 20 g of cobalt nitrate was added thereto and the mixture was stirred in a N2 atmosphere for 35 min. The mixture was centrifuged and the precipitate was collected and washed with deionized water three times. The mixture was dried in an oven at 65°C for 9 h and calcined in a muffle furnace at 250°C for 8 h. The mixture was then reduced in a tubular furnace with H2 at 280°C for 4 h to obtain the composite material.

[0078] The catalysts prepared in the examples and comparative examples were subjected to performance tests, and the test results are shown in Table 1.

[0079] Table 1 Catalyst performance test results

[0080]

[0081] As can be seen from Table 1, the catalyst prepared by the present invention has a larger average specific surface area and average pore size, and a larger crushing strength, which is more conducive to improving the catalytic performance.

[0082] The catalysts prepared in the above examples and comparative examples were used to photocatalytically degrade toluene. The degradation method in the comparative example was the same as that in Example 1. The test results are shown in Table 2.

[0083]

[0084] η is the degradation rate of toluene, M 反应初 and M 反应后 are the toluene concentration before and after the reaction, respectively.

[0085] Table 2 Photocatalytic degradation of toluene test results

[0086]

[0087] Comparative Example 1 contains only NiBr2, without loading Co and AgBr. The carrier recombination rate is high, but the plasma resonance effect of Co nanoparticles is lacking, and visible light absorption cannot be enhanced; the AgBr / NiBr2 heterojunction is not formed, resulting in rapid recombination of photogenerated electron-hole pairs.

[0088] Comparative Example 2 is Co / NiBr2, which is not loaded with AgBr. Although Co / NiBr2 has the electron mediation effect of Co, it lacks the energy band matching between AgBr and NiBr2 and cannot form a Type-II heterojunction.

[0089] Comparative Example 3 uses AgBr / NiBr2 without Co loading. While the AgBr / NiBr2 heterojunction expands the light absorption range, the lack of Co nanoparticles prevents the localized light field from being enhanced via LSPR. The lack of Co leads to insufficient excitation intensity of photogenerated electrons, limiting the charge separation efficiency.

[0090] In Comparative Example 4, the high ammonia concentration leads to agglomeration and reduces the specific surface area, resulting in a decrease in active sites, making it difficult for reactant molecules to contact the catalyst surface, and reducing the catalytic efficiency.

[0091] In Comparative Example 5, O2 in the air caused the Co nanoparticles to oxidize to CoO / Co3O4, losing the electron-mediating function of metallic Co. The oxidized Co became a recombination center, accelerating the recombination of electron-hole pairs and significantly reducing the catalytic activity.

[0092] In Comparative Example 6, the excess AgNO₃ (0.6 g) generated too much AgBr, which caused the van der Waals forces between particles to cause agglomeration. AgBr covered the active sites on the Co / NiBr₂ surfaces, hindering the adsorption of reactants and the photoexcitation process.

[0093] In Comparative Example 7, AgBr was loaded first and Co was loaded later, resulting in loose contact between Co and the AgBr / NiBr2 interface, interrupting the electron transfer path. The synergistic effect between the heterojunction and Co was weakened, and the charge separation efficiency was reduced.

Claims

1. A method for preparing a AgBr / Co / NiBr2 composite catalyst, characterized in that: The following steps are involved: 1) Preparation of NiBr2: Add nickel acetate to ethylene glycol solvent and stir to form a transparent solution. Add KBr to the solution and stir until the KBr is completely dissolved. Then, add 4%-8% ammonia water to the mixed solution, stir at 20-30°C for 4-6 hours, dry at 60-70°C for 24-48 hours, and calcine at 500-600°C for 3-5 hours to obtain the product NiBr2. 2) Preparation of Co / NiBr2 composite material: The NiBr2 product from step 1) was dispersed in water and uniformly dispersed by ultrasonication. Cobalt nitrate was added thereto and stirred for 30-40 minutes. The mixture was centrifuged and the precipitate was collected, washed, dried, calcined in a muffle furnace, and then reduced in a tubular furnace with H2 to obtain a Co / NiBr2 composite material. 3) Preparation of AgBr / Co / NiBr2 composite material: The Co / NiBr2 composite material was dispersed in ethanol and uniformly dispersed by ultrasonication. AgNO3 was added thereto and stirred for 10-20 minutes. KBr was then added thereto and the mixture was reacted in a water bath at 80-90°C until the ethanol was completely evaporated. The solid product was collected and calcined at 150-200°C for 3-6 hours to obtain an AgBr / Co / NiBr2 composite catalyst. The reaction in step 2) is carried out in an N2 or Ar atmosphere; In step 3), the mass volume ratio of AgNO3, KBr and ethanol is (2-5) g: (1.4-3.5) g: (10-15) mL.

2. The method for preparing the AgBr / Co / NiBr2 composite catalyst according to claim 1, wherein In step 1), the mass volume ratio of nickel acetate, KBr and ethylene glycol is (3-5) g: (2.8-4.8) g: (25-30) mL.

3. The method for preparing the AgBr / Co / NiBr2 composite catalyst according to claim 1, wherein In step 1), the volume ratio of ammonia water to ethylene glycol is 1:3-2:

1.

4. The method for preparing the AgBr / Co / NiBr2 composite catalyst according to claim 1, wherein In step 2), the mass volume ratio of cobalt nitrate to water is (10-20) g: (30-50) mL.

5. The method for preparing the AgBr / Co / NiBr2 composite catalyst according to claim 1, wherein: In step 2), the drying step is carried out in an oven at 60-70°C for 8-10 hours. In step 2), the calcination step is carried out at a temperature of 200-300°C for 6-10 hours. The H2 reduction step is carried out at a temperature of 200-300°C for 4-5 hours.

6. The AgBr / Co / NiBr2 composite catalyst prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the AgBr / Co / NiBr2 composite catalyst as claimed in claim 6 in photocatalytic degradation of toluene in wastewater, characterized in that: The following steps are involved: a) The prepared catalyst is placed in a quartz glass tube of a photoreactor. The photoreactor is set at a temperature of 20-30°C and a pressure of 0.1-0.3 MPa. b) adding photocatalytic degradation wastewater into a quartz tube, sealing the quartz tube, and introducing helium into the liquid film photoreactor under dark conditions at a flow rate of 90-110 mL / min for a time of 20-40 min, and exhausting the gas in the reactor; c) Under irradiation with a xenon lamp at a power of 300-400W, after 5-10 hours of reaction, measure the toluene concentration before and after the reaction.

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