Composite catalyst based on abnormal adsorbate type strong metal-carrier interaction, and preparation method and application thereof

Abstract

The invention relates to the technical field of environmental catalysis and advanced oxidation, in particular to a composite catalyst based on abnormal adsorbate type strong metal-carrier interaction (AA-SMSI), a preparation method of the composite catalyst and activation application of the composite catalyst to potassium peroxymonosulfate (PMS). The composite catalyst comprises a nanoscale carrier CeO2 and cobalt nanoparticles which are loaded on the carrier and have a core-shell structure. The unique core-shell structure of the composite catalyst effectively inhibits leaching of cobalt ions and aggregation of nano particles through physical packaging, the stability is greatly improved, the under-coordination shell layer of the composite catalyst also serves as a high-activity site, the PMS activation capacity is remarkably enhanced, and therefore ultrahigh activity and stability are achieved at the same time. The preparation process of the composite catalyst is mild, controllable and environment-friendly, a new thought is provided for breaking through the bottleneck that activity and stability in a traditional catalytic system are difficult to consider at the same time, and the composite catalyst has wide application prospects in the fields of advanced oxidation, industrial wastewater treatment and environmental catalysis.

Description

Technical Field

[0001] This application relates to the fields of environmental catalysis and advanced oxidation technology, specifically to a composite catalyst based on anomalous adsorbate-type strong metal-support interaction (AA-SMSI) and its preparation method, as well as its application in PMS-activated degradation of organic pollutants. Background Technology

[0002] Organic pollutants refer to pollutants composed of natural organic matter such as carbohydrates, proteins, amino acids and fats, as well as some other biodegradable artificially synthesized organic matter. They can have a negative impact on the ecosystem and harm human health.

[0003] Current treatment methods in my country often employ traditional PMS activation systems, which frequently utilize transition metal oxide catalysts. However, due to issues such as easy metal ion loss and unstable support interfaces, it is difficult to simultaneously achieve both catalyst activity and stability. Existing research indicates that strong metal-support interactions (SMSI) can partially improve metal dispersion and anti-sintering properties; however, traditional SMSI often relies on high-temperature treatment or reducing atmospheres, which can easily lead to the covering or aggregation of active sites, thus reducing catalytic performance. Therefore, overcoming the activity / stability trade-off caused by SMSI and designing PMS catalytic systems that achieve both high activity and high stability has become an urgent issue to be addressed in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application aims to provide a simple method for constructing an anomalous adsorbate-type strong metal-support interaction (AA-SMSI) structure, fundamentally improving the reactivity and structural stability of the catalyst, and providing a novel and efficient catalytic system for PMS-based advanced oxidation processes. This is achieved through the following technical solution.

[0005] The primary objective of this application is to provide a composite catalyst with an undercoordinated metal shell. The composite catalyst comprises a nanoscale support CeO2 and cobalt nanoparticles with a core-shell structure supported on the support. The cobalt nanoparticles are cobalt crystal core structures coated with an undercoordinated cobalt layer. The diameter of the cobalt nanoparticles is 20 nm-50 nm, and the thickness of the undercoordinated cobalt layer is 3 nm-5 nm. The cobalt content in the composite catalyst with the undercoordinated metal shell is 2%-5% of the mass of the support.

[0006] Furthermore, the carrier is a nanorod or nanosheet.

[0007] The second objective of this application is to provide a method for preparing the above-mentioned composite catalyst, comprising the following steps: S1, dissolving soluble cerium salt, sodium hydroxide and sodium chloride in water, and obtaining nanoscale support CeO2 through hydrothermal reaction and post-treatment; S2, dispersing the support CeO2 in an organic solvent, adding a cobalt salt precursor and stirring and mixing, filtering and drying to obtain a cobalt-containing precursor powder; S3, adding an adsorbate to the cobalt-containing precursor powder, mixing evenly, placing it in a tube furnace and continuously introducing a reducing atmosphere for high-temperature heat treatment to induce the formation of an anomalous adsorbate-type strong metal-support interaction (AA-SMSI) structure, thereby obtaining a composite catalyst with an undercoordinated metal shell.

[0008] Furthermore, step S1 shall satisfy at least one of the following: (1) the ratio of soluble cerium salt, sodium hydroxide and sodium chloride in volume molar concentration (M) is (0.06-0.10): (7.20-12.4): (0.73-0.12); (2) the hydrothermal reaction temperature is 180℃-200℃ and the reaction time is 20 h-24 h.

[0009] Furthermore, step S2 must satisfy at least one of the following: (1) the organic solvent is methanol; (2) the concentration of cobalt ions in the cobalt salt precursor is 0.01 M-0.1 M; (3) the stirring and mixing operation time is 12 h-24 h; and (4) the drying temperature is 60℃-80℃.

[0010] Furthermore, step S3 shall satisfy at least one of the following: (1) the adsorbate is urea, and the mass ratio of urea to cobalt precursor / CeO2 mixture is (0.5-5):1; (2) the reducing atmosphere is a hydrogen-argon mixture with a hydrogen gas fraction of 5%-10%; (3) the high-temperature heat treatment procedure is: heating to 600℃-800℃ at a rate of 5℃ / min-10℃ / min and holding for 1 h-3 h.

[0011] The third objective of this application is to provide an application of the above-mentioned composite catalyst in the PMS-activated degradation of organic pollutants, wherein the composite catalyst prepared according to the above preparation method and PMS are added to water containing organic pollutants for oxidative degradation.

[0012] Furthermore, the application of this composite catalyst in the PMS-activated degradation of organic pollutants must meet at least one of the following conditions: (1) the concentration of PMS is 0.5 g / L-2.0 g / L, the concentration of organic pollutants is 10 mg / L-20 mg / L, and the dosage of the composite catalyst is 0.1 g / L-0.5 g / L; (2) the organic pollutants include one or more of carbamazepine, tetracycline, bisphenol A, ciprofloxacin, norfloxacin, or rhodamine B; (3) the background matrix of the water body includes pH, inorganic anions, inorganic cations, and natural organic matter (humic acid), wherein the pH is 2-10, the dosage concentration of inorganic anions and cations is 5 mM-20 mM, the dosage concentration of humic acid is 10 mM-30 mM, and the inorganic anion is Cl. - PO4 3- SO4 2- Or NO3 - One or more of the following, wherein the inorganic cation is Na + Mg 2+ K + or Ca 2+ One or more of the following; (4) The water body is an actual water body, which is tap water, lake water, river water, groundwater or industrial wastewater.

[0013] Furthermore, the application must meet at least one of the following performance requirements: (1) the removal rate of a single type of organic pollutant is 80%-100% after 2 minutes of use of the composite catalyst; (2) the removal rate of 20 mg / L carbamazepine by the composite catalyst remains at 90% or above after 5 consecutive cycles of use, and the cobalt metal leaching amount is ≤0.1 mg / L.

[0014] Furthermore, the application includes the composite catalyst achieving a removal rate of ≥95% for carbamazepine (20 mg / L) in water bodies with different background matrices, and a removal rate of ≥90% for carbamazepine (20 mg / L) in different actual water bodies.

[0015] Compared with the prior art, this application has the following beneficial effects:

[0016] (1) This application relates to a composite catalyst Co CF @Co ULThis composite catalyst overcomes the activity-stability trade-off by, for the first time, constructing an anomalous adsorbate-induced strong metal-support interaction in a Co / CeO2 catalyst system. This effect prompts cobalt nanoparticles to reconfigure themselves into an undercoordinated shell, rather than the carrier migration and coverage of traditional strong metal-support interactions (SMSI). This unique core-shell structure not only effectively inhibits cobalt ion leaching and nanoparticle aggregation through physical encapsulation, greatly improving stability, but its undercoordinated shell itself also serves as a highly active site, significantly enhancing PMS activation ability, thus achieving both ultra-high activity and stability.

[0017] (2) The composite catalyst Co of this application CF @Co UL The preparation method is safe, controllable, and reproducible. This application introduces urea as an adsorbate to precisely induce the reconstruction of cobalt nanoparticles under specific high-temperature reduction conditions. The preparation method is simple, the conditions are controllable, it is environmentally friendly, and it is easy to scale up for production, providing a new universal strategy for designing high-performance environmental catalysts.

[0018] (3) The composite catalyst Co of this application CF @Co UL It exhibits excellent catalytic performance in the PMS-activated degradation of carbamazepine (CBZ), achieving 100% removal within 2 minutes and an apparent rate constant as high as 2.544 min. -1 The normalized rate constant reaches 628.2 min. -1 ·M -1 Meanwhile, the composite catalyst maintained an activity of over 90% after five cycles of 20 mg / L carbamazepine, and the cobalt leaching concentration remained below 0.05 mg / L, far exceeding the most stringent recycled water standards.

[0019] (4) The composite catalyst Co of this application CF @Co UL The reaction pathway is optimized, resulting in broad environmental adaptability. This composite catalyst activates PMS primarily to generate singlet oxygen, and its dominant non-radical pathway is minimally affected by the background matrix of the water body (pH, inorganic ions, and natural organic matter). This allows the catalytic system to maintain high efficiency in various real-world water bodies (tap water, lake water, river water, groundwater, and industrial wastewater), demonstrating strong potential for practical applications. Attached Figure Description

[0020] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0021] Figure 1 Co crystal plane @ Co undercoordination shell (Co CF @Co UL) structural diagram;

[0022] Figure 2 Co crystal plane @ Co undercoordination shell (Co CF @Co UL Transmission electron microscope image of )

[0023] Figure 3 Co crystal plane @ Co undercoordination shell (Co CF @Co UL Comparison of carbamazepine degradation efficiency between the PMS and PMS systems;

[0024] Figure 4 Co crystal plane @ Co undercoordination shell (Co CF @Co UL Kinetic fitting diagram of carbamazepine degradation in the PMS system;

[0025] Figure 5 Co crystal plane @ Co undercoordination shell (Co CF @Co UL The cyclic stability of the catalyst and the cobalt leaching concentration are shown in the figure.

[0026] Figure 6 Co crystal plane @ Co undercoordination shell (Co CF @Co UL Removal efficiency of the PMS system for different organic pollutants;

[0027] Figure 7 Co crystal plane @ Co undercoordination shell (Co CF @Co UL Removal effect of PMS system in different environmental matrices. Detailed Implementation

[0028] The present application will be further described below with reference to specific embodiments. These embodiments are only used to more clearly illustrate the technical solutions of the present application and should not be construed as limiting the scope of protection of the present application. Anything not described in detail in this patent application is considered common knowledge in the art.

[0029] The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available or synthesized by conventional methods and are ready for use without further processing, as are the instruments used in the examples. All technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0030] To overcome the aforementioned problems, this invention proposes an atypical adsorbate-induced strong metal-support interaction (AA-SMSI) mechanism. This mechanism induces cobalt atom migration and structural reconstruction on the support surface through a reducing adsorbate (urea), resulting in a stable complex with an undercoordinated metal shell and a synergistic interface structure. The undercoordinated metal shell is entirely composed of cobalt, without any cerium migration from the CeO2 support. This structure not only effectively promotes electron transfer and non-radical generation but also significantly inhibits metal leaching, thereby achieving a highly efficient and sustainable PMS activation reaction.

[0031] This application provides a composite catalyst with an undercoordinated metal shell, the structure of which is as follows: Figure 1 As shown, the composite catalyst includes nanoscale nanorods or nanosheets of CeO2 as a support, and cobalt nanoparticles with a core-shell structure supported on the support. The cobalt nanoparticles are cobalt crystal core structures coated with an undercoordinated cobalt layer. The diameter of the cobalt nanoparticles is 20 nm-50 nm, the thickness of the undercoordinated cobalt layer is 3 nm-5 nm, and the Co element content in the composite catalyst with the undercoordinated metal shell is 2%-5% of the support mass.

[0032] In a preferred embodiment of this application, the preparation method of the above-mentioned composite catalyst with a poorly coordinated metal shell includes the following steps: S1, dissolving soluble cerium salt, sodium hydroxide, and sodium chloride in water at a molar concentration (M) ratio of (0.06-0.10):(7.20-12.4):(0.73-0.12), and obtaining nanoscale support CeO2 through hydrothermal reaction (reaction temperature 180℃-200℃, reaction time 20 h-24 h) and post-treatment; S2, dispersing the obtained support CeO2 in an organic solvent, adding a cobalt salt precursor (cobalt ion concentration 0.01 M-0.1 M), and stirring for 12 h-24 h. h, after filtration and drying (drying temperature is 60℃-80℃), cobalt-containing precursor powder is obtained; wherein, the organic solvent can be methanol; S3, add adsorbate (urea) to cobalt-containing precursor powder, mix evenly, place in a tube furnace and continuously introduce a reducing atmosphere (hydrogen-argon mixture with hydrogen gas fraction of 5%-10%) for high-temperature heat treatment (heating to 600℃-800℃ at a rate of 5℃ / min-10℃ / min, and holding for 1 h-3 h), to induce the formation of an anomalous adsorbate-type strong metal-support interaction (AA-SMSI) structure, and obtain a composite catalyst with an undercoordinated metal shell; wherein, the mass ratio of urea to cobalt precursor / CeO2 mixture is (0.5-5):1.

[0033] In a preferred embodiment of this application, the composite catalyst has wide applications in PMS-activated degradation of organic pollutants, and can degrade organic pollutants such as disinfectants, antibiotics, and dyes, including but not limited to one or more of carbamazepine, tetracycline, bisphenol A, ciprofloxacin, norfloxacin, or rhodamine B. In another preferred embodiment of this application, the composite catalyst is applied in water bodies with different background matrices and in different actual water bodies, by adding different pH values ​​and inorganic anions (Cl-) before degradation. - PO4 3- SO4 2- Or NO3 - One or more of the following), inorganic cations (Na+) + Mg 2 + K + or Ca 2+ The same degradation operation is performed on the following: one or more of the following substances) and natural organic matter (humic acid), and the solution is changed to actual water bodies (tap water, lake water, river water, groundwater and industrial wastewater); the pH is 2-10, the concentration of inorganic anions and cations is 5 mM-20 mM, and the concentration of humic acid is 10 mM-30 mM.

[0034] In a preferred embodiment of this application, the specific steps for applying the composite catalyst are as follows: adding the composite catalyst and PMS to water containing organic pollutants, wherein the concentration of PMS is 0.5 g / L-2.0 g / L, the concentration of organic pollutants is 10 mg / L-20 mg / L, and the dosage of the composite catalyst is 0.1 g / L-0.5 g / L.

[0035] In a preferred embodiment of this application, the composite catalyst achieves a removal rate of 80%-100% for a single type of organic pollutant after 2 minutes of use; for example, the composite catalyst achieves a removal rate of ≥95% for carbamazepine (20 mg / L) in different background matrix water bodies and a removal rate of ≥90% for carbamazepine (20 mg / L) in different actual water bodies.

[0036] In a preferred embodiment of this application, the composite catalyst is recyclable. After the reaction, the composite catalyst is recovered, washed, dried, and then subjected to the same degradation operation. This process is repeated five times, and the removal rate of pollutants and the concentration of cobalt ions in the solution are measured each time. Taking carbamazepine as an example, the composite catalyst maintains a removal rate of 90% or higher for 20 mg / L carbamazepine after five consecutive cycles (each cycle lasting at least 2 minutes), with a cobalt metal leaching amount ≤0.1 mg / L.

[0037] Example 1: Preparation of composite catalyst

[0038] This embodiment provides a Co crystal plane@Co undercoordination shell (Co CF @Co UL Composite catalysts Figure 2 This is a transmission electron microscope (TEM) image of the catalyst (Co). CF @Co UL The preparation method of ) is as follows:

[0039] S1. Weigh a certain amount of CeCl3·7H2O, NaOH, and NaCl to prepare solutions with concentrations of 0.06 M, 7.20 M, and 0.73 M respectively in 50 mL of deionized water. Stir magnetically until completely dissolved, then transfer the mixed solution to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene. Seal the reactor and place it in an oven. React at 180℃ for 24 hours. After the reaction, allow it to cool naturally to room temperature. Repeatedly filter and wash the resulting pale yellow precipitate with deionized water until the filtrate is neutral. Place the washed solid product in an oven and dry it overnight at 80℃. After grinding, CeO2 nanorod carriers are obtained for later use.

[0040] S2. Accurately weigh 0.1 g of the CeO2 nanorod support prepared in step S1, and uniformly disperse it in 50 mL of methanol. Add a certain amount of Co(NO3)2·6H2O to the solution to make the theoretical loading of Co 3 wt.%; Stir magnetically at room temperature for 12 hours to ensure that the cobalt salt precursor is fully adsorbed. Then, stir and evaporate the solution at 60℃ to obtain a powdered precursor.

[0041] S3. Mix the dried precursor powder and urea at a mass ratio of 1:1, and spread the mixture evenly in a ceramic boat. Place the ceramic boat in the center of the constant temperature zone of a tube furnace. After sealing the tube furnace, purge with a 5% H2 / Ar mixed gas (flow rate 100 mL / min) for 30 minutes to remove air from the tube. Then, heat the tube furnace to 700℃ at a heating rate of 5℃ / min and maintain the temperature at 700℃ for 2 hours. After the heat treatment, stop heating and allow the furnace to cool naturally to room temperature under continuous ventilation. Remove the sample to obtain the Co crystal plane@Co undercoordinated shell (Co). CF @Co UL The target catalyst.

[0042] from Figure 2 As can be seen from the data, the Co-CeO2 catalyst consists of Co cores and undercoordinated Co shells (Co... UL ), Co UL (3-5 nm) completely encapsulates the Co core.

[0043] Comparative Example 1

[0044] The conditions and operations are basically the same as in Example 1, except that urea is not added in step S3 to provide the adsorbate.

[0045] Comparative Example 2

[0046] The conditions and operations are basically the same as in Example 1, except that Co(NO3)2·6H2O is not added in step S2 to provide the cobalt source and urea is not added in step S3 to provide the adsorbate.

[0047] Comparative Example 3

[0048] The conditions and operations are basically the same as in Example 1, except that Co(NO3)2·6H2O is not added in step S2 to provide a cobalt source.

[0049] Experimental Example 1: Degradation Capacity Test

[0050] To evaluate the Co crystal plane @ Co undercoordination shell (Co CF @Co ULThe degradation ability of the catalyst was tested by catalytic degradation experiments in 250 mL beakers at room temperature. The experimental subject was carbamazepine (CBZ), and each experiment was set up in triplicate.

[0051] Specifically, 50 mL of a 20 mg / L carbamazepine (CBZ) aqueous solution was added to a beaker. The catalyst prepared in Example 1 (final concentration 0.1 g / L) and persulfate (PMS, final concentration 0.5 g / L) were added sequentially. The conical flask was then immediately placed on a magnetic stirrer and the reaction was initiated at 450 rpm. At preset time points (0 s, 20 s, 40 s, 60 s, 80 s, 100 s, and 120 s), approximately 1 mL of the reaction solution was taken, and an equal volume of Na2S2O3 solution was immediately added to quench the reaction. The solution was then filtered through a 0.22 μm aqueous filter, and the residual concentration of CBZ in the filtrate was determined by high-performance liquid chromatography (HPLC).

[0052] Degradation effect such as Figure 3 As shown, the efficient degradation of carbamazepine was successfully achieved. Figure 3 Co can be seen from CF @Co UL The PMS system achieved nearly 100% degradation of CBZ within 2 minutes.

[0053] Figure 4 The kinetic fit of the catalyst to CBZ is shown, indicating that Co CF @Co UL The apparent rate constant (k obs The time was 2.544 min. -1 Under the same conditions, the comparative sample prepared without urea showed a degradation rate of 79.7% within 2 minutes, k obs It is 0.876 min -1 Furthermore, the degradation of CBZ by adding only PMS, CeO2 / PMS, and NC-CeO2 / PMS is negligible. This indicates that the Co prepared in this invention... CF @Co UL The catalyst exhibits extremely excellent PMS activation performance.

[0054] Experiment 2, Stability Test

[0055] To evaluate the Co crystal plane @ Co undercoordination shell (Co CF @Co UL To assess the stability of the catalyst, a carbamazepine (CBZ) degradation cycle experiment was conducted, following the method described in Experimental Example 1.

[0056] Specifically, each reaction lasted 2 minutes. After the reaction, the catalyst was recovered by centrifugation, washed twice with deionized water, and then dried at 60°C for use in the next cycle. Simultaneously, after each reaction, the reaction solution was collected, and the concentration of cobalt ions in the solution was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0057] The results are as follows Figure 5 As shown, Co CF @Co UL Even after five consecutive uses, the catalyst maintained a degradation efficiency of over 90% for CBZ. Furthermore, the leaching concentration of cobalt ions remained below 0.05 mg / L throughout the entire cycle, demonstrating the catalyst's excellent structural stability and environmental safety.

[0058] Example 2: Application of Composite Catalysts

[0059] This embodiment aims to illustrate the Co crystal plane@Co undercoordinated shell (Co) prepared in Example 1. CF @Co UL The applicability and stability of this product in complex aquatic environments were evaluated. The degradation effect on carbamazepine (CBZ) was assessed by simulating different background matrices and using various real water bodies.

[0060] Add 0.1 g / L catalyst and 0.5 g / L PMS to 50 mL of carbamazepine (20 mg / L) aqueous solution, react at room temperature for 2 minutes, and evaluate the reaction by systematically changing the background matrix of the water body and the actual water body:

[0061] S1, Influence of Inorganic Anions: Introducing 10 mM Cl into the reaction system - PO4 3- SO4 2- and NO3 - ;

[0062] S2, pH effect: The initial pH of the reaction system was adjusted to 2.38, 4.12, 6.85, 8.92 and 10.12 respectively using HCl or NaOH solution;

[0063] S3, Influence of Inorganic Cations: 10 mM Na was introduced into the reaction system. + Mg 2+ K + and Ca 2+ ;

[0064] S4. Influence of natural organic matter: Add humic acid (HA) of different concentrations (10-30 mg / L) to the reaction system.

[0065] S5. Actual water body test: Use actual water bodies (including tap water, lake water, river water, groundwater and industrial wastewater) collected from different sources as the reaction matrix.

[0066] During degradation, the solution was continuously stirred at 450 rpm at room temperature. At preset time intervals, approximately 1 mL of the suspension was taken each time, immediately quenched with an equal volume of Na₂S₂O₃ solution, filtered through a 0.22 μm membrane, and the concentration of residual pollutants was measured. Furthermore, carbamazepine was replaced with aqueous solutions of tetracycline, bisphenol A, ciprofloxacin, norfloxacin, and rhodamine b, respectively, to investigate the broad-spectrum activity of the composite catalyst against different pollutants.

[0067] The results are as follows Figure 6 and Figure 7 As shown. Figure 6 This indicates that under different pH values, in the presence of inorganic anions, inorganic cations, and natural organic matter, Co... CF @Co UL The PMS system maintained a removal efficiency of over 98% for CBZ, with no significant inhibitory effect observed. The removal rate of CBZ in tap water, lake water, river water, and groundwater all reached approximately 95%, and even in industrial wastewater with more complex composition, it could still achieve a high-efficiency removal of approximately 90%. Figure 7 This indicates that the composite catalyst has broad applicability and can effectively remove a variety of pollutants, including bisphenol A, ciprofloxacin, norfloxacin, tetracycline, and rhodamine B.

[0068] Based on the preferred embodiments of this application, and through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A composite catalyst with an under-coordinated metal shell layer, comprising a nanoscale support CeO2, and cobalt nanoparticles with a core-shell structure supported on the support, the cobalt nanoparticles being a cobalt crystal face core structure coated with an under-coordinated Co layer, the diameter of the cobalt nanoparticles being 20-50 nm, the thickness of the under-coordinated Co layer being 3-5 nm, and the content of Co element in the composite catalyst with an under-coordinated metal shell layer being 2-5% of the mass of the support.

2. The composite catalyst according to claim 1, wherein the support is a nanorod or a nanosheet.

3. A method for preparing the composite catalyst according to claim 1 or 2, comprising the following steps: S1. dissolving a soluble cerium salt, sodium hydroxide and sodium chloride in water, and obtaining a nanoscale support CeO2 through a hydrothermal reaction and post-processing; S2. dispersing the support CeO2 in an organic solvent, adding a cobalt salt precursor and stirring to mix, and obtaining a cobalt-containing precursor powder after filtration and drying; S3. adding an adsorbate to the cobalt-containing precursor powder, uniformly mixing, and placing in a tube furnace and continuously introducing a reducing atmosphere for high-temperature heat treatment, to induce the formation of an abnormal adsorbate type strong metal-support interaction (AA-SMSI) structure, and obtain a composite catalyst with an under-coordinated metal shell layer.

4. The method according to claim 3, wherein the step S1 at least meets one of the following: (1) the use amount ratio of the soluble cerium salt, the sodium hydroxide and the sodium chloride, in terms of volume molar concentration (M), is (0.06-0.10):(7.20-12.4):(0.73-0.12); (2) the reaction temperature of the hydrothermal reaction is 180-200℃, and the reaction time is 20-24 h.

5. The method according to claim 3, wherein the step S2 at least meets one of the following: (1) the organic solvent is methanol; (2) the concentration of cobalt ions in the cobalt salt precursor is 0.01-0.1 M; (3) the stirring and mixing operation time is 12-24 h; (4) the drying temperature is 60-80℃.

6. The method according to claim 3, wherein the step S3 at least meets one of the following: (1) the adsorbate is urea, and the mass ratio of the urea to the cobalt precursor / CeO2 mixture is (0.5-5):1; (2) the reducing atmosphere is hydrogen argon mixed gas with a hydrogen volume fraction of 5-10%; (3) the high-temperature heat treatment program is: heating at a rate of 5-10℃ / min to 600-800℃, and maintaining for 1-3 h.

7. Use of the composite catalyst according to claim 1 or 2 in the activation of PMS to degrade organic pollutants, wherein the composite catalyst prepared according to any one of the preparation methods of claims 3-6 and PMS are added to a water body containing organic pollutants for oxidative degradation.

8. The use according to claim 7, wherein at least one of the following is met: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) the PMS is added at a concentration of 0.5 g / L-2.0 g / L, the organic pollutant is added at a concentration of 10 mg / L-20 mg / L, and the composite catalyst is added at a dosage of 0.1 g / L-0.5 g / L; (2) the organic pollutant comprises one or more of carbamazepine, tetracycline, bisphenol A, ciprofloxacin, norfloxacin, or rhodamine b; (3) the background matrix of the water body comprises pH, inorganic anions, inorganic cations and natural organic matter (humic acid), the pH is 2-10, the inorganic anions and cations have a dosing concentration of 5 mM-20 mM, the humic acid has a dosing concentration of 10 mM-30 mM, the inorganic anions are one or more of Cl - , PO4 3- , SO4 2- or NO3 - , and the inorganic cations are one or more of Na + , Mg 2+ , K + or Ca 2+ ; (4) the water body is an actual water body, and the actual water body is tap water, lake water, river water, underground water, or industrial wastewater.

9. The use according to claim 8, at least meeting one of the following: (1) the removal rate of the composite catalyst for a single kind of organic pollutant is 80%-100% after 2 minutes of use; (2) the removal rate of the composite catalyst for 20 mg / L of carbamazepine remains at 90% or above after 5 cycles of continuous use, and the cobalt metal leaching amount is ≤0.1 mg / L.

10. The use according to claim 8, wherein the removal rate of the composite catalyst for carbamazepine (20 mg / L) in different background matrix water bodies is ≥95%, and the removal rate of the composite catalyst for carbamazepine (20 mg / L) in different actual water bodies is ≥90%.

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