A cobalt monatomic catalyst, a preparation method and application thereof
Patent Information
- Application Number
- CN202610884845.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-18
- Publication Date
- 2026-09-15
Smart Images
Figure CN122745929A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of environmental functional materials technology, and in particular to a cobalt single-atom catalyst, its preparation method, and its application. Background Technology
[0002] Advanced persulfate (PMS)-based oxidation processes have become an important technology in water treatment due to their strong oxidizing power and high efficiency in removing recalcitrant organic pollutants. Traditional PMS activation largely relies on the free radical pathway, but the resulting sulfate or hydroxyl radicals are easily affected by background water components and have limited contact efficiency with pollutants in heterogeneous systems, leading to low oxidant utilization. Furthermore, under complex water quality conditions, there are issues with insufficient selectivity and stability in the degradation of antibiotic-like pollutants. In recent years, non-radical oxidation pathways, particularly direct electron transfer mechanisms, have attracted widespread attention due to their high selectivity, strong resistance to interference, and high oxidant utilization. This pathway forms PMS complexes on the catalyst surface, directly oxidizing pollutants and thus avoiding the limitations of the free radical pathway.
[0003] Single-atom catalysts have shown great potential in PMS activation due to their near 100% atomic utilization, well-defined active center structure, and tunable coordination environment. Among them, cobalt-based single-atom catalysts exhibit excellent performance in non-radical electron transfer pathways due to their suitable d-band electronic structure and good redox properties. Currently, most research focuses on single-atom catalysts with Co-N4 coordination structures. For example, patent CN115350728A proposes a nitrogen-coordinated single-atom cobalt catalyst, its preparation method, and its application. A nano-thick carbon-nitrogen layer containing atomically dispersed cobalt species was successfully decorated on carbon nanotubes via a low-temperature solvothermal reaction. By adjusting the added cobalt content, the coordination number of nitrogen in the atomically dispersed Co species was controlled to four and five (Co-N4 / CNT and Co-N5 / CNT), which can be directly used as a catalyst for PMS activation without high-temperature pyrolysis. Furthermore, it can be applied to the degradation of various sulfonamide antibiotics, all showing high degradation efficiency. However, this saturated coordination structure limits its adsorption configuration and electronic control ability for PMS molecules.
[0004] In contrast, structures such as Co-N3-C with unsaturated coordination numbers can generate more exposed active sites with more easily tunable electronic structures, which theoretically are more conducive to the adsorption activation and subsequent electron transfer processes of PMS. However, systematic and in-depth research is still lacking on the specific mechanisms of action, structure-activity relationships, and preparation and regulation strategies of these unsaturated coordination structures in PMS activation, especially in the non-radical degradation pathway of antibiotic pollutants in complex water bodies. Furthermore, there are few reports on low-cost and industrially producible methods for preparing cobalt-based single-atom catalysts with unsaturated coordination structures. Summary of the Invention
[0005] The purpose of this invention is to overcome the defects and shortcomings of existing PMS activation catalysts and provide a cobalt single-atom catalyst with high electron transfer efficiency, which can efficiently activate PMS and achieve rapid degradation of antibiotic pollutants by forming surface PMS complexes to mediate electron transfer pathways; it also has high selectivity and stability in the degradation of antibiotic pollutants under complex water quality conditions.
[0006] Another objective of this invention is to provide a method for preparing a cobalt single-atom catalyst, which is simple, reproducible, and uses low-cost raw materials, making it suitable for large-scale production.
[0007] Another object of the present invention is to provide the application of a cobalt single-atom catalyst in the activation of persulfate.
[0008] Another object of the present invention is to provide a method for degrading antibiotic pollutants, which is carried out using the cobalt single-atom catalyst and persulfate.
[0009] The above-mentioned objective of this invention is achieved through the following technical solution: The present invention provides a cobalt single-atom catalyst, comprising a nitrogen-doped carbon support and a cobalt single-atom active site supported on the nitrogen-doped carbon support, wherein the cobalt single atom forms a planar quadrilateral Co-N3C1 coordination structure with three nitrogen atoms and one carbon atom in the carbon support; the atomic percentage of the cobalt single atom in the cobalt single-atom catalyst is 0.2-2%.
[0010] It should be noted that: The catalyst of this invention incorporates cobalt atoms in the interstitial spaces of a graphite carbon support in the form of single atoms, constructing a single-atom electronic interaction structure, increasing the active sites of the catalyst, and simultaneously enhancing the inherent catalytic activity. The single-atom catalyst enables electron transfer from the reactants to the PMS through the catalyst sites, promoting the adsorption / activation of reactants at the interstitial cobalt sites, while simultaneously accelerating the adsorption of reactants at the metal sites, forming a unique non-radical pathway catalytic effect. This effectively overcomes the technical problem of traditional carbon-supported metal catalysts lacking metal-support electronic interactions, catalytic reactions only occurring through the metal active sites, limiting reactant mass transport and the generation of reactive oxygen species, resulting in low catalytic activity.
[0011] Furthermore, the single-atom electron interaction in the single-atom catalyst described in this invention can promote the efficient electron cycle of the catalyst, enabling the catalyst to maintain excellent stability. After multiple catalytic cycles, it can still maintain high catalytic activity and can be repeatedly regenerated and used.
[0012] In some embodiments, the atomic percentage of the cobalt single atom in the cobalt single atom catalyst is 0.5-1.5%, preferably 0.8-1.2%.
[0013] In some embodiments, the cobalt single atom is embedded in the graphene lattice plane of the nitrogen-doped carbon support, with the Co-N bond length being 1.89±0.02Å and the Co-C bond length being 1.84±0.02Å.
[0014] In some embodiments, the nitrogen-doped carbon support of the single-atom catalyst of the present invention has a carbon nanosheet stacked structure; this structure can fully expose the active sites while promoting contact between the reaction sites and the reactants.
[0015] This invention provides a method for preparing a cobalt single-atom catalyst, comprising the following steps: The cobalt salt solution and the nitrogen-doped carbon support precursor solution were mixed evenly and dried. The mixture was then calcined at 600-900°C under an inert atmosphere and allowed to cool naturally to obtain the cobalt single-atom catalyst.
[0016] During calcination, metal ions in soluble metal salts are reduced to form elemental metal particles, while metal atoms are incorporated into the interstitial spaces of the carbon lattice. During calcination, cobalt ions are reduced and coordinate with nitrogen atoms in the nitrogen-doped carbon support, forming atomically dispersed Co-N. x The increased graphitization of the carbon support at active sites helps stabilize metal single atoms and enhances electron conductivity. However, excessively high calcination temperatures can lead to carbon support structural collapse and active site aggregation; conversely, insufficient precursor decomposition results in amorphous carbon covering the active sites, reducing catalyst exposure and activity. Calcination time affects the metal-support bonding strength and coordination environment, thereby modulating the catalyst's adsorption and activation performance for PMS.
[0017] Preferably, the calcination temperature is 800-900℃, more preferably 830-870℃, and even more preferably 840-860℃. Suitable high temperatures contribute to the formation of a more ordered carbon structure and stronger metal-support interactions; this invention controls a relatively high temperature range to form a stable coordination structure, ensuring that metal atoms are firmly anchored to the support and preventing aggregation in subsequent applications.
[0018] In some embodiments, the method for preparing the cobalt single-atom catalyst includes the following steps: S1, dissolve pyromellitic acid and dicyandiamide in an aqueous solvent, and adjust the pH value to 7.5-9 with ammonia water to obtain a mixed solution of precursors; S2, add the cobalt salt solution dropwise to the precursor mixture solution, stir evenly at 38-42℃, dry, and grind to obtain precursor powder; S3, the precursor powder is calcined at 600~900℃ for 1.5-3h under an inert atmosphere to obtain the cobalt single-atom catalyst.
[0019] The preparation method of this invention uses trimellitic acid and dicyandiamide as carbon and nitrogen sources, respectively. Under weakly alkaline conditions (pH = 7.5-9), trimellitic acid is deprotonated to promote coordination with subsequently added cobalt ions, achieving molecular-level pre-assembly. This invention effectively avoids premature precipitation and segregation of metal ions through an aqueous solution method, resulting in highly dispersed Co-N. x -C single-atom catalysts are an important guarantee. Specifically, the formation of single-atom cobalt centers is closely related to the coordination environment. It requires controlling the dissolution temperature of the metal salt and organic ligands (trimethylammonium sulfide, dicyandiamide), adjusting the pH of the system, and optimizing the method of adding the metal salt. This effectively avoids precursor segregation and premature precipitation of metal ions in the aqueous system, providing a feasible solution for constructing atomically dispersed metal-nitrogen-carbon active centers in the aqueous phase. Optimizing the mixing temperature of the cobalt salt with the carbon and nitrogen sources promotes the coordination reaction between cobalt ions and organic ligands, stabilizing the coordination state of cobalt in the precursor. This is crucial for forming atomically dispersed Co-N / C structures during subsequent high-temperature calcination. Simultaneously, adjusting the ratio of metal salt to nitrogen / carbon sources as needed can regulate the metal concentration during calcination. The formation of nitrogen coordination structures and the degree of nitrogen doping; while calcination temperature directly affects the reduction of cobalt ions, atomic-level dispersion, and Co-N. x The construction stability of the -C active sites determines the final catalyst's coordination structure and PMS activation performance.
[0020] Preferably, in step S1, the temperature at which the pyromellitic acid and dicyandiamide are dissolved in the aqueous solvent is 50-70°C; heating is used to ensure that the pyromellitic acid and dicyandiamide are fully dispersed.
[0021] In some embodiments, in step S1, the mass ratio of the pyromellitic acid to dicyandiamide is (0.5-2):10.
[0022] Preferably, the drying step in S2 is as follows: the obtained mixed solution is transferred to a rotary evaporator, and the solvent is evaporated and removed in a water bath at 60-70°C to form a solid precursor, which is then ground into powder to obtain precursor powder; the solvent is removed gently by rotary evaporation to retain the uniformity of the precursor.
[0023] In some embodiments, in step S3, the heating rate is 4-6°C / min.
[0024] This invention provides an application of the cobalt single-atom catalyst in the activation of persulfate.
[0025] Furthermore, the cobalt single-atom catalyst is used in the activation of persulfate to degrade organic pollutants.
[0026] Preferably, the organic pollutant is an antibiotic pollutant.
[0027] The present invention provides a method for degrading antibiotic pollutants, the method comprising using persulfate and the cobalt single-atom catalyst in an environment where degradation is required.
[0028] The cobalt single-atom catalyst of this invention has a single-atom electronic interaction structure. In the reaction system for removing antibiotic pollutants by activating PMS, PMS molecules are adsorbed on the catalyst surface through single-atom metal active sites, generating PMS* surface complexes. These complexes promote electron transfer between pollutant molecules and the complexes in a mediating manner, forming a unique non-radical pathway catalytic effect, which efficiently degrades antibiotic pollutants.
[0029] Furthermore, the cobalt single-atom catalyst of the present invention can undergo rapid redox cycles, ensuring the stability of the catalyst and preventing the reduction of active sites and catalytic activity even after repeated use.
[0030] In some embodiments, the antibiotic contaminant includes at least one of levofloxacin hydrochloride (LEV), sulfamethoxazole (SMX), chloramphenicol, acetaminophen (PCM), tetracycline (TC), naproxen (NPX), bisphenol A (BPA), and carbamazepine (CBZ).
[0031] Preferably, the antibiotic contaminant is an electron-rich contaminant, which includes, but is not limited to, levofloxacin hydrochloride (LEV), acetaminophen (PCM), tetracycline (TC), naproxen (NPX), and carbamazepine (CBZ).
[0032] In some embodiments, the concentration of the antibiotic contaminant is 0.1-10 mg / L.
[0033] In some embodiments, the concentration of persulfate in the degradation reaction system is 0.5-1 mM, and the concentration of the cobalt single-atom catalyst is 0.01-0.2 g / L.
[0034] In some embodiments, the pH of the environment requiring degradation can be 3 to 9; exemplaryly, the pH value is any one of 3, 4, 5, 6, 7, 8, or 9, or a range between two of them. The catalyst of the present invention has good acid-base adaptability and can function stably over a wide pH range of the reaction system.
[0035] Furthermore, the cobalt single-atom catalyst exhibits strong resistance to interference and can be used in complex aquatic environments. The reaction remains stable even with selective adjustment of different ion interference conditions, such as Cl... - CO3² - SO4² - NO3 - And the environment that is disturbed by humic acid and other substances.
[0036] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a cobalt single-atom catalyst that enhances its intrinsic catalytic activity by constructing an M-N3C1 coordination structure to regulate the active center and electronic structure. The single-atom electronic interaction structure promotes electron transfer from pollutants to PMS, optimizing the adsorption and activation energy barriers for PMS. It exhibits excellent oxidation efficiency and high selectivity for antibiotic pollutants rich in electron-rich groups. Furthermore, the catalyst demonstrates strong resistance to interference, maintaining high catalytic performance even in complex water conditions (such as those with chloride ions, carbonate ions, and humic acid); it also exhibits high stability, maintaining stable catalytic activity within the pH range of 3-9, and its catalytic efficiency decreases by only 10% after five reuses. Attached Figure Description
[0037] Figure 1 Transmission electron microscope images of the catalysts of Example 1 and Comparative Example 1; wherein, Figure 1 a and Figure 1 c represents a conventional transmission electron microscope (TEM) image and a spherical aberration electron microscope (AC-TEM) image of the catalyst in Example 1, respectively. Figure 1 b and Figure 1 d represents the conventional transmission electron microscope (TEM) image and the high-resolution transmission electron microscope (HR-TEM) image of Comparative Example 1, respectively.
[0038] Figure 2 The powder X-ray diffraction patterns of the catalysts in Example 1 and Comparative Examples 1-2 are shown.
[0039] Figure 3 X-ray photoelectron spectroscopy (XPS) spectra of the catalysts of Example 1 and Comparative Example 1 were obtained.
[0040] Figure 4 In-situ Raman spectra of the catalysts of Example 1 and Comparative Example 1 were obtained.
[0041] Figure 5 This is a fitted diagram of the X-ray absorption fine structure spectrum of the cobalt single-atom catalyst in Example 1.
[0042] Figure 6 This is a schematic diagram of the simulation model of the cobalt single-atom catalyst in Example 1.
[0043] Figure 7This is a comparison chart of the removal efficiency of PMS activated by cobalt single-atom catalyst in Example 1 for different pollutants. Detailed Implementation
[0044] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.
[0045] Example 1 A cobalt single-atom catalyst includes a nitrogen-doped carbon support and cobalt single-atom active sites supported on the nitrogen-doped carbon support, wherein the cobalt single atom forms a planar quadrilateral Co-N3C1 coordination structure with three nitrogen atoms and one carbon atom in the carbon support; the content of the cobalt single atom in the cobalt single-atom catalyst is 0.94%.
[0046] The method for preparing the cobalt single-atom catalyst includes the following steps: S1, 300 mg of pyromellitic acid and 3 g of dicyandiamide were added to 50 mL of deionized water and stirred at 60°C for 2 h until completely dissolved. After naturally cooling to 40°C, the pH value was adjusted to 8 with ammonia water to obtain a precursor mixed solution. S2, Dissolve 8.6 mg of cobalt chloride hexahydrate in 5 ml of deionized water to prepare a cobalt salt solution, slowly add it dropwise to the precursor mixture solution, and continue to stir evenly at 40°C to obtain a mixed solution; transfer it to a rotary evaporator, evaporate and remove the solvent in a 65°C water bath to form a solid precursor, grind it into powder to obtain precursor powder; S3, the precursor powder is placed in a tube furnace and calcined at 850°C for 2 hours under a N2 atmosphere at a rate of 5°C / min to obtain a carbon-supported metal salt precursor, wherein the N2 flow rate is 100 mL / min. After calcination, the temperature is lowered to room temperature, and the material is ground in an agate mortar for 5 minutes to obtain the cobalt single-atom catalyst, denoted as CoNC.
[0047] Example 2 A cobalt single-atom catalyst differs from Example 1 in that the calcination conditions in this example are: heating to 700°C at 3°C / min and calcining for 3.5 hours.
[0048] Example 3 A cobalt single-atom catalyst differs from Example 1 in that the calcination conditions in this example are: heating to 800°C at 3°C / min and calcining for 2 hours.
[0049] Example 4 A cobalt single-atom catalyst, which differs from Example 1 in that: in the preparation method of the cobalt single-atom catalyst described in this example, the amount of cobalt chloride hexahydrate added is 7.2 mg.
[0050] Example 5 A method for degrading antibiotic pollutants includes the following steps: taking 50 mL of water containing antibiotic pollutants (levofloxacin hydrochloride concentration 10 mg / L, pH=5.7), adding 5 mg of the cobalt single-atom catalyst prepared in Example 1, adding 1 mM persulfate to the reaction system, and after the degradation reaction for 30 minutes, the antibiotic pollutants are degraded.
[0051] Example 6 A method for degrading antibiotic contaminants, which differs from Example 5 in that the antibiotic contaminant in this example is acetaminophen (PCM) at 10 mg / L.
[0052] Example 7 A method for degrading antibiotic contaminants, which differs from Example 5 in that the antibiotic contaminant in this example is tetracycline (TC) at 10 mg / L.
[0053] Example 8 A method for degrading antibiotic contaminants, which differs from Example 5 in that the antibiotic contaminant in this example is naproxen (NPX) at 10 mg / L.
[0054] Example 9 A method for degrading antibiotic contaminants, which differs from Example 5 in that the antibiotic contaminant in this example is bisphenol A (BPA) at 10 mg / L.
[0055] Example 10 A method for degrading antibiotic contaminants, which differs from Example 5 in that the antibiotic contaminant in this example is sulfamethoxazole (SMX) 10 mg / L.
[0056] Comparative Example 1 A metal particle-doped catalyst, the preparation method of which includes the following steps: S1, 300 mg of pyromellitic acid and 3 g of dicyandiamide were added to 50 mL of deionized water and stirred at 60°C for 2 h until completely dissolved. After naturally cooling to 40°C, the pH value was adjusted to 8 with ammonia water to obtain a precursor mixed solution. S2, the precursor mixture obtained in step S1 is transferred to a rotary evaporator and the solvent is removed by evaporation in a 65°C water bath to form a solid precursor; 17.1 mg of cobalt chloride hexahydrate is added to the solid precursor and ground and mixed evenly to obtain precursor powder; S3, the precursor powder is placed in a tube furnace and calcined at 700℃ for 3.5 h under a N2 atmosphere, with the temperature increased at 3℃ / min. The lower calcination temperature and longer calcination time are beneficial for forming thermodynamically more stable oxide crystal particles, resulting in a uniformly dispersed carbon-supported metal salt precursor. The N2 flow rate is 100 mL / min. After calcination, the temperature is lowered to room temperature, and the material is ground in an agate mortar for 5 min to obtain the metal particle-doped catalyst, denoted as Co3O4 / NC.
[0057] Comparative Example 2 A nitrogen-doped carbon catalyst, the preparation method of which includes the following steps: S1, 300 mg of pyromellitic acid and 3 g of dicyandiamide were added to 50 mL of deionized water and stirred at 60 °C for 2 h until completely dissolved to obtain a precursor mixed solution; S2, the precursor mixture obtained in step S1 is transferred to a rotary evaporator, and the solvent is removed by evaporation in a 65°C water bath to form a solid precursor, which is then ground into powder to obtain precursor powder. S3, the precursor powder is placed in a tube furnace and calcined at 700℃ for 3.5 h under a N2 atmosphere at a rate of 3℃ / min to obtain a carbon-supported metal salt precursor, wherein the N2 flow rate is 100 mL / min. After calcination, the temperature is lowered to room temperature, and the material is ground in an agate mortar for 5 min to obtain the nitrogen-doped carbon catalyst, denoted as NC.
[0058] Comparative Example 3 A method for degrading antibiotic pollutants includes the following steps: taking 50 mL of water containing antibiotic pollutants (levofloxacin hydrochloride concentration 10 mg / L, pH=5.7), adding 5 mg of the metal particle-doped catalyst prepared in Comparative Example 1, adding 1 mM persulfate to the reaction system, and after the degradation reaction for 30 minutes, the antibiotic pollutants are degraded.
[0059] Comparative Example 4 A method for degrading antibiotic pollutants includes the following steps: taking 50 mL of water containing antibiotic pollutants (levofloxacin hydrochloride concentration 10 mg / L, pH=5.7), adding 5 mg of the nitrogen-doped carbon catalyst prepared in Comparative Example 2, adding 1 mM persulfate to the reaction system, and performing the degradation reaction for 30 minutes to achieve the degradation treatment of antibiotic pollutants.
[0060] Performance testing 1. TEM characterization The catalysts of Example 1 and Comparative Example 1 were examined using transmission electron microscopy (TEM) and aberration electron microscopy, and the results are as follows: Figure 1 As shown.
[0061] from Figure 1 It can be seen that in the single-atom catalyst of Example 1, Co metal is dispersed in the support in an atomic-level form. In contrast, the supported metal particle catalyst of Comparative Example 1 shows obvious agglomeration of metal oxide particles, and the CoO4(311) lattice stripes indicate its crystallinity.
[0062] 2. XRD characterization The catalysts of Example 1 and Comparative Examples 1-2 were characterized by powder X-ray diffraction patterns, and the results are as follows: Figure 2 As shown.
[0063] from Figure 2 It can be seen that the single-atom catalyst CoNC described in Example 1 of this invention has the same C(002) and C(101) graphite diffraction peaks as the Co3O4 / NC and NC catalysts in Comparative Examples 1-2; indicating that there are abundant defect structures in the NC substrate, and the abundant defect structures provide relatively suitable coordination conditions for the coordination of Co single atoms.
[0064] Among them, Co3O4 / NC exhibited characteristic diffraction peaks of Co3O4 between 2θ and 40°, proving the successful synthesis of well-crystallized nanoparticles. In contrast, the single-atom catalysts CoNC and NC did not show any characteristic diffraction peaks of cobalt metal or cobalt oxide, indicating that cobalt was highly dispersed in the support in atomic form and did not form Co nanoparticle aggregates that reached the XRD detection limit.
[0065] 3. XPS characterization The catalysts of Example 1 and Comparative Example 1 were characterized by X-ray photoelectron spectroscopy, and the results are as follows: Figure 3 As shown.
[0066] from Figure 3 It can be seen that the single-atom catalyst described in Example 1 is indeed cobalt metal doped on the support in the form of single atoms; wherein there is a peak belonging to the Co-N coordination bond at the binding energy of 399.82 eV, and the Co metal content is 0.94%.
[0067] The Co3O4 / NC in Comparative Example 1 has a peak of Co-O bond oxide at a binding energy of 530.32 eV, indicating that it is a nanoparticle doped on a support with a Co content of 1.26%.
[0068] 4. In-situ Raman spectroscopy characterization The catalysts of Example 1 and Comparative Example 1 were characterized by in-situ Raman spectroscopy, and the results are as follows: Figure 4 As shown.
[0069] The results show that the single-atom catalyst in Example 1 can adsorb PMS to form a PMS complex during the reaction, which is a key process mediating the non-radical electron transfer pathway.
[0070] 5. XAFS characterization and simulation model X-ray absorption fine structure spectroscopy (XAFS) analysis was performed on the catalyst (CoNC) obtained in Example 1, using Co-foil, CoO, Co-Pc, and Co3O4 as standard reference samples. The results of spectrum fitting are as follows: Figure 5 As shown.
[0071] Using Materials Studio software, a Co-NC single-atom catalyst model was constructed based on graphene crystal files. The model was then structurally optimized using density functional theory (DFT) calculations. The results are as follows: Figure 6 As shown, the theoretical Co-N bond length is 1.907 Å and the Co-C bond length is 1.835 Å.
[0072] The phase-corrected XAFS experimental results are in high agreement with the DFT calculation results, proving that the Co atoms mainly exist in the form of single atoms, which form a planar quadrilateral Co-N3C1 coordination structure with three N atoms and one C atom in the carbon support.
[0073] 5. Catalytic efficiency test The antibiotic pollutants were treated using the degradation methods described in Examples 5-10 and Comparative Examples 3-4. After 30 minutes of degradation, the pollutant removal efficiency (C) was used as the metric. t / C0% indicates catalytic performance, and the results are as follows: Figure 7 As shown in Table 1.
[0074] Table 1. Catalytic efficiency test results
[0075] As shown in Table 1, the CoNC-activated PMS catalyst of this invention can achieve the degradation and removal of antibiotic pollutants with a removal efficiency of ≥77%. Specifically, the CoNC-activated PMS catalyst of this invention achieves a 100% removal efficiency for electron-rich pollutants (LEV, PCM, TC, NPX). The catalyst in Comparative Example 1, loaded with metal agglomerates, lacks single-atom active sites and achieves a 92% removal efficiency for LEV, but its degradation time is significantly longer than that of the CoNC catalyst of this invention. The catalyst in Comparative Example 2, without metal atoms, achieves a final catalytic efficiency of only 24% for LEV.
[0076] 6. Acid-base suitability test The antibiotic pollutant degradation method of Example 5 was used to treat 50 mL of pollutant (LEV) for 20 min. The pH value of the system was controlled by pH adjuster (H2SO4 or NaOH). The test results are expressed as LEV removal rate, and the results are shown in Table 2.
[0077] Table 2 Results of Acid-Base Suitability Test
[0078] As can be seen from Table 2, the single-atom catalyst CoNC of the present invention exhibits excellent catalytic activation performance of PMS for the degradation of levofloxacin hydrochloride under different pH conditions, with good acid and alkali adaptability, and is suitable for water treatment in different environments.
[0079] 7. Ion interference resistance test The antibiotic-type pollutant degradation method described in Example 5 was used to treat 50 mL of pollutant (LEV) for 30 min. Simultaneously, 5 mM of soluble metal salt and humic acid (HA) were added to each system to interfere with the background. The test results are expressed as the degradation rate of levofloxacin hydrochloride, and the results are shown in Table 3.
[0080] Table 3. Results of Anti-interference Performance Test
[0081] As can be seen from Table 3, the single-atom catalyst CoNC of the present invention still exhibits excellent catalytic activation performance for the degradation of levofloxacin hydrochloride by PMS under all ion interference conditions. It has strong anti-interference ability, is suitable for various environmental conditions, and can be widely used for the removal of antibiotic pollutants.
[0082] 8. Stability Test The antibiotic pollutant degradation method of Example 5 was used to treat 50 mL of pollutant (LEV) for 30 min, and the change in the removal rate of pollutant degradation by activated PMS was recorded after the catalyst was repeatedly used 5 times.
[0083] Table 4 Stability Test Results
[0084] As can be seen from Table 4, the single-atom catalyst CoNC described in this invention maintains a 100% removal rate of levofloxacin hydrochloride within 5 reaction cycles, demonstrating the advantages of high efficiency and stability.
[0085] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A cobalt monatomic catalyst characterized in that, It includes a nitrogen-doped carbon support and a cobalt single-atom active site supported on the nitrogen-doped carbon support. The cobalt single atom forms a planar quadrilateral Co-N3C1 coordination structure with three nitrogen atoms and one carbon atom in the carbon support. The atomic percentage of the cobalt single atom in the cobalt single-atom catalyst is 0.2% to 2%.
2. The cobalt-atomic catalyst according to claim 1, wherein The atomic percentage of the cobalt single atom in the cobalt single atom catalyst is 0.5~1.5%.
3. The Co single-atom catalyst of claim 1, wherein, The cobalt single atom is embedded in the graphene lattice plane of the nitrogen-doped carbon support, with the Co-N bond length being 1.89±0.02Å and the Co-C bond length being 1.84±0.02Å.
4. A method for preparing the cobalt monatomic catalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: The cobalt salt solution and the nitrogen-doped carbon support precursor solution were mixed evenly and dried. The mixture was then calcined at 600-900°C under an inert atmosphere and allowed to cool naturally to obtain the cobalt single-atom catalyst.
5. The method of producing a cobalt-atomic catalyst according to claim 4, wherein Includes the following steps: S1, dissolve pyromellitic acid and dicyandiamide in an aqueous solvent, and adjust the pH value to 7.5-9 with ammonia water to obtain a mixed solution of precursors; S2, add the cobalt salt solution dropwise to the precursor mixture solution, stir evenly at 38-42℃, dry, and grind to obtain precursor powder; S3, the precursor powder is calcined at 600~900℃ for 1.5-3h under an inert atmosphere to obtain the cobalt single-atom catalyst.
6. The method of producing a cobalt-atomic catalyst according to claim 5, wherein In step S1, the mass ratio of pyromellitic acid to dicyandiamide is (0.5-2):
10.
7. The method of producing a cobalt-atomic catalyst according to claim 5, wherein In step S3, the heating rate is 4-6℃ / min.
8. The use of a cobalt single-atom catalyst according to any one of claims 1-3 in the activation of persulfate.
9. A method of degrading antibiotic-type pollutants, characterized in that, The method includes the use of persulfate and the cobalt single-atom catalyst according to any one of claims 1-3 in an environment where degradation is required.
10. The method for degrading antibiotic pollutants according to claim 9, characterized in that, The concentration of persulfate in the degradation reaction system is 0.5-1 mM, and the concentration of the cobalt single-atom catalyst is 0.01-0.2 g / L.