Copper-doped cerium oxide antifouling agent as well as preparation method and application thereof

Abstract

The invention discloses a copper-doped cerium oxide antifouling agent and a preparation method and application thereof.The antifouling agent takes cerium oxide as a main body material, copper is introduced for doping, Cu < 2 + > partially replaces Ce < 4 + > to enter crystal lattices, charge imbalance is caused, more oxygen vacancies are induced to be generated, meanwhile, reduction conversion from Ce < 4 + > to Ce < 3 + > is promoted, and formation of the oxygen vacancies is further stabilized. The oxygen vacancies obviously enhance the surface catalytic activity of the material, H2O2 and Br <-> in seawater can be efficiently catalyzed to generate hypobromous acid (HOBr) with a bactericidal effect, the function of natural halogenated peroxidase is simulated, and long-acting and environment-friendly biological antifouling is realized. The antifouling agent provided by the invention can be synthesized by adopting a hydrothermal method, is simple and convenient in process, is suitable for large-scale preparation, is suitable for various marine environment antifouling scenes such as hulls, marine engineering equipment and underwater sensors, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of nanotechnology, specifically relating to a copper-doped cerium oxide antifouling agent, its preparation method, and its application. Background Technology

[0002] Water transport plays a vital role in global economic development due to its low cost and high efficiency. Biofouling is a key challenge restricting the long-term performance of marine engineering equipment and vessels. Especially in high-salt, high-humidity marine environments, metal structures are highly susceptible to the adhesion of marine organisms such as bacteria, algae, and shellfish, accelerating structural aging and severely impacting equipment operating efficiency. Taking marine vessels as an example, biofouling significantly increases surface roughness, reduces sailing speed, increases drag, leads to increased fuel consumption and CO2 emissions, and may even induce equipment malfunctions, posing safety risks. Therefore, biofouling has become a critical issue that urgently needs to be addressed for the sustainable development of marine engineering.

[0003] Among numerous antifouling technologies, antifouling coatings are the most economical, effective, and widely applicable method. However, traditional antifouling coatings release harmful antifouling agents that are difficult to decompose (such as organotin), polluting the ecological environment. Furthermore, these agents can enter the human food chain via fish, shellfish, and other organisms, seriously threatening human health. Currently, most countries have restricted the use of traditional antifouling agents, and the development of green antifouling coatings has become an important direction for marine antifouling.

[0004] Halogenated peroxidases are a class of natural antifouling agents secreted by marine algae, effectively inhibiting the attachment of fouling organisms and achieving green antifouling; however, the extraction of these enzymes is difficult and unstable, limiting their practical application. Research has found that cerium oxide nanoparticles can catalyze the reaction of H₂O₂ and Br₂. - The formation of hypobromic acid (HOBr) is similar in mechanism to that of natural halogenated peroxidases. Meanwhile, cerium oxide possesses excellent chemical stability, is not easily dissolved in seawater, and does not release harmful particles, making it an environmentally friendly material. Therefore, cerium oxide nanoparticles, combining stability and environmental friendliness, hold promise as a novel green antifouling agent, replacing natural halogenated peroxidases. However, the enzyme-like activity of nano-cerium oxide is currently lower than that of natural enzymes, and its catalytic efficiency is limited. Further improving the enzyme-like activity of nano-cerium oxide is a key technological challenge for its efficient application in marine antifouling. Summary of the Invention

[0005] The purpose of this invention is to provide a copper-doped cerium oxide antifouling agent, its preparation method, and its application. This is achieved by introducing copper as a dopant, thereby increasing the cerium oxide content of the copper oxide. 2+ Partially replaces Ce 4+ Entering the crystal lattice causes a charge imbalance, thereby inducing the generation of more oxygen vacancies and simultaneously promoting Ce. 4+ To Ce 3+The reduction and transformation further stabilizes the formation of oxygen vacancies. These oxygen vacancies significantly enhance the surface catalytic activity of the material, enabling efficient catalysis of H2O2 and Br in seawater. - Hypobromic acid (HOBr) with bactericidal effect is generated, which mimics the function of natural halogenated peroxidase, to achieve long-lasting and environmentally friendly biofouling prevention, and solves the problem of insufficient antifouling performance of nano-cerium oxide as a coating antifouling agent.

[0006] A copper-doped cerium oxide antifouling agent with the molecular formula Cu x Ce 1-x O 2-x , where x is 0.05-0.2.

[0007] The preparation method of the above-mentioned copper-doped cerium oxide antifouling agent includes the following steps: (1) Dissolve copper salt and cerium salt in deionized water and slowly introduce them into alkaline solution to obtain a mixed solution; (2) The above mixture was stirred continuously at room temperature until it was homogeneous, and the color of the mixture changed from yellow to purple; (3) Transfer to a high-pressure reactor lined with polytetrafluoroethylene and hydrothermally react at 80~100℃ for 12~24h to produce precipitate; (4) The product is purified to obtain copper-doped cerium oxide powder.

[0008] According to the above scheme, the cerium salt mentioned in step (1) is cerium nitrate (Ce(NO3)3·6H2O); the copper salt is copper nitrate (Cu(NO3)2·3H2O).

[0009] According to the above scheme, the final concentration of cerium salt in the mixed solution obtained in step (1) is 40-60 mmol / L.

[0010] According to the above scheme, in step (1), the amount of copper salt is controlled so that the doping ratio in the obtained copper-doped cerium oxide is in the range of 5~20 mol%.

[0011] According to the above scheme, the alkaline solution mentioned in step (1) is an aqueous solution of sodium hydroxide with a concentration of 0.08-0.12 mol / L.

[0012] According to the above scheme, the stirring time in step (2) is 0.5~1h.

[0013] According to the above scheme, the hydrothermal reaction temperature in the optimized scheme of step (3) is 85-95℃ and the reaction time is 16-20h.

[0014] According to the above scheme, the purification process in step (4) includes: centrifuging at high speed with a centrifuge, discarding the supernatant to obtain the precipitate, washing repeatedly with deionized water until the pH is close to 7, and freeze-drying to obtain the powder sample.

[0015] The above-mentioned copper-doped cerium oxide antifouling agent is used as a coating antifouling agent.

[0016] According to the above scheme, the amount of copper-doped cerium oxide antifouling agent used in the coating ranges from 1 to 5 wt%.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: Nano-cerium oxide exhibits lower enzyme-like activity than natural enzymes, resulting in limited catalytic efficiency. Its antibacterial ability is further weakened, especially after incorporation into coatings. In contrast, the copper-doped cerium oxide nanoparticles of this invention, when applied to antifouling coatings, retain high antibacterial activity, representing a significant improvement over traditional nano-cerium oxide. Conventional nano-cerium oxide, after incorporation into coatings, easily has its surface active sites covered, leading to decreased enzyme-like activity and weakened antibacterial effect. This invention addresses this by doping copper into the cerium oxide lattice... 2+ Replace Ce 4+ This can lead to lattice charge imbalance, thereby inducing the formation of more oxygen vacancies. Cu doping can also promote Ce formation. 4+ Partially restored to Ce 3+ This further stabilizes the presence of oxygen vacancies and significantly enhances the free radical (·OH, O2) activity. - The material's continuous generation capability allows it to maintain high antibacterial and antifouling activity even in coated environments.

[0018] Traditional metal antifouling agents, such as cuprous oxide and zinc oxide, pose a significant risk of releasing large amounts of metal ions into seawater, potentially harming marine ecosystems. The copper element in the material of this invention exists stably as a dopant, preventing large-scale leaching. This reduces the environmental toxicity of copper while achieving highly efficient antifouling, meeting the development needs of green and environmentally friendly ship coatings. Furthermore, this antifouling agent is synthesized via a hydrothermal method, resulting in a simple, low-cost process suitable for large-scale production.

[0019] The copper-doped cerium oxide coating antifouling agent of this invention has both salt corrosion resistance and light stability. It can maintain stable catalytic and antifouling effects in complex marine environments such as high salinity and ultraviolet irradiation, thereby ensuring the reliability and durability of the coating during long-term use. Attached Figure Description

[0020] Figure 1 XRD patterns and magnified views of nano-cerium oxide and nano-cerium oxide doped with different concentrations of copper.

[0021] Figure 2 Raman plots of nano-cerium oxide and nano-cerium oxide with different concentrations of copper doping.

[0022] Figure 3XPS images of nano-cerium oxide and nano-cerium oxide with different concentrations of copper doped with different concentrations: (a) XPS full spectrum, (b) O 1s high-resolution spectrum, (c) Ce 3d high-resolution spectrum, (d) Cu 2p high-resolution spectrum.

[0023] Figure 4 TEM images of nano-cerium oxide and nano-cerium oxide doped with different concentrations of copper, where ae corresponds to Examples 1-5.

[0024] Figure 5 Graphs showing the antifouling properties of the antifouling agents obtained in Examples 1-5 when applied to coating materials.

[0025] In the figures, the labels (1), (2), (3), (4), and (5) correspond to embodiments 1-5. Detailed Implementation

[0026] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0027] Example 1 Pure cerium oxide nanomaterials without copper doping (Cu x Ce 1-x O 2-x Preparation of (where x is 0): Dissolve 0.868g Ce(NO3)3·6H2O in 10mL of deionized water, which is called solution A; dissolve 0.16g sodium hydroxide in 30mL of deionized water, which is called solution B, and stir well; pour solution A into solution B, stir at room temperature for 30 minutes at a speed of 600 rpm; after stirring, pour the mixture into a reaction vessel and hydrothermally react at 100℃ for 24 hours. After the reaction, allow it to cool naturally to room temperature, centrifuge at high speed (8000 rpm, 5 min), discard the supernatant, and repeatedly wash the precipitate with deionized water until the solution pH is close to 7 to ensure the removal of impurities. Finally, resuspend the precipitate in deionized water, freeze-dry and grind thoroughly to obtain nano-cerium oxide powder.

[0028] The cerium oxide nanomaterials prepared in Example 1 were characterized as follows: Figure 1-4 As shown, the characterization results are as follows: XRD spectrum ( Figure 1 The characteristic peaks of fluorine-containing CeO2 are observed, mainly corresponding to planes such as (111), (200), (220), (311), (222), and (400); Raman spectra ( Figure 2 ) at 462 cm -1 A distinct F2g vibrational peak appears at this point; XPS full spectrum ( Figure 3 The sample contained only Ce and O elements, and the high-resolution Ce 3d spectrum indicated that Ce was present in Ce form. 3+ / Ce4+ Mixed valence states exist, Ce 3+ The presence of oxygen vacancies indicates their formation, and the O 1s spectrum further confirms the presence of lattice oxygen and defect oxygen; TEM ( Figure 4 a) The results showed that the sample had a short rod-like morphology.

[0029] Example 2 5% copper-doped cerium oxide nanomaterials (Cu x Ce 1-x O 2-x Preparation of (where x is 0.05): 0.868 g Ce(NO3)3·6H2O and 0.0254 g Cu(NO3)2·3H2O were dissolved in 10 mL of deionized water, which is called solution A; 0.16 g sodium hydroxide was dissolved in 30 mL of deionized water, which is called solution B, and the mixture was stirred evenly. Solution A was poured into solution B and stirred at room temperature for 30 minutes at a speed of 600 rpm. After stirring, the mixture was poured into a reaction vessel and hydrothermally reacted at 100℃ for 24 hours. After the reaction, the mixture was naturally cooled to room temperature and centrifuged at high speed (8000 rpm, 5 min). The supernatant was discarded, and the precipitate was repeatedly washed with deionized water until the pH of the solution was close to 7 to ensure the removal of impurities. Finally, the precipitate was resuspended in deionized water, freeze-dried, and thoroughly ground to obtain nano-cerium oxide powder.

[0030] Characterization of the 5% copper-doped cerium oxide nanomaterials prepared in Example 2 is as follows: Figure 1-4 As shown, the characterization results are as follows: XRD patterns ( Figure 1 In the study, the characteristic peaks of Cu-doped cerium oxide nanorods were basically consistent with those of pure CeO2, but the diffraction peaks shifted slightly to higher angles, indicating that the lattice contracted. This is because Cu... 2+ An ion (radius 0.073 nm) partially substitutes Ce. 4+ (Radius 0.097 nm) leads to a decrease in the lattice constant. Raman spectroscopy ( Figure 2 The significantly weakened F2g peak intensity and broadened peak shape in the XPS spectrum indicate decreased lattice distortion and crystallinity, and an increase in the number of oxygen vacancies. Figure 3 In addition to Ce and O, Cu element signals were observed, and high-resolution Cu 2p spectra showed Cu as a component of Cu. + and Cu 2+ The coexistence of these states indicates successful doping, with peak shape analysis of Ce 3d and O 1s showing an increase in oxygen vacancy content. TEM image ( Figure 4 b) The rod-shaped morphology is more obvious, with uniform size and clear edges.

[0031] Example 3 10% copper-doped cerium oxide nanomaterials (Cu xCe 1-x O 2-x Preparation of Cu(NO3)2·3H2O (where x is 0.1): The amount of Cu(NO3)2·3H2O used is 0.0537 g, and the remaining steps are the same as in Example 2.

[0032] Characterization of the 10% copper-doped cerium oxide nanomaterials prepared in Example 3 is as follows: Figure 1-4 As shown, the characterization results are as follows: XRD patterns ( Figure 1 The lattice shows further contraction, and the diffraction peaks continue to shift to higher angles; Raman spectroscopy ( Figure 2 The F2g peak in the XPS spectrum further weakened, the defect peaks strengthened, and the oxygen vacancy concentration continued to increase; Figure 3 The Cu signal is obvious, and the Cu 2p peak corresponds to Cu + and Cu 2+ Price state, Ce 3+ The content of CeO2 increased compared to pure CeO2, indicating an increase in oxygen vacancies; TEM image ( Figure 4 c) The rod-like structure appears more regular.

[0033] Example 4 15% copper-doped cerium oxide nanomaterials (Cu x Ce 1-x O 2-x Preparation of Cu(NO3)2·3H2O (where x is 0.15): The amount of Cu(NO3)2·3H2O used is 0.0853 g, and the remaining steps are the same as in Example 2.

[0034] Characterization of the 15% copper-doped cerium oxide nanomaterials prepared in Example 4 is as follows: Figure 1-4 As shown, the characterization results are as follows: XRD patterns ( Figure 1 The lattice shows further contraction, and the diffraction peaks continue to shift to higher angles; Raman spectroscopy ( Figure 2 The F2g peak in the XPS spectrum further weakened, the defect peaks strengthened, and the oxygen vacancy concentration continued to increase; Figure 3 The Cu signal is obvious, and the Cu 2p peak corresponds to Cu + and Cu 2+ Price state, Ce 3+ The content of CeO2 increased compared to pure CeO2, indicating an increase in oxygen vacancies; TEM image ( Figure 4 d) The rod-shaped morphology is complete.

[0035] Example 5 20% copper-doped cerium oxide nanomaterials (Cu x Ce 1-x O 2-x Preparation of Cu(NO3)2·3H2O (where x is 0.2): The amount of Cu(NO3)2·3H2O used is 0.1208 g, and the remaining steps are the same as in Example 2.

[0036] Characterization of the 20% copper-doped cerium oxide nanomaterials prepared in Example 5 is as follows: Figure 1-4 As shown, the characterization results are as follows: XRD patterns ( Figure 1 The lattice shows further contraction, and the diffraction peaks continue to shift to higher angles; Raman spectroscopy ( Figure 2 The F2g peak in the XPS spectrum is further weakened, while the defect peak is enhanced, indicating a further increase in oxygen vacancy concentration. Figure 3 The Cu signal is obvious, and the Cu 2p peak corresponds to Cu + and Cu 2+ Price state, Ce 3+ The content of CeO2 increased compared to pure CeO2, indicating an increase in oxygen vacancies; TEM ( Figure 4 e) The rod-shaped morphology is clearly and completely displayed.

[0037] In practical applications, the copper-doped cerium oxide antifouling agent of this invention can be composited with common coating substrates (such as epoxy, polyurethane, acrylic, or silicone resins). The obtained antifouling agent is added at a ratio of 0.1-5 wt% of the coating solids content and mixed using conventional dispersion processes (high-speed shearing, ultrasonic-assisted, etc.) to obtain an antifouling coating. Application can be by spraying or scraping, with a dry film thickness of 80-150 μm.

[0038] To investigate the antibacterial properties of CeO2 nanoparticles due to halogen peroxidase activity, seven experimental groups were established: Control group 1 (concentration of 10... 6 The bacterial suspensions were divided into three groups: control group 2 (E. coli suspension supplemented with 25 mmol / L NH4Br and 0.1 mmol / L H2O2), and experimental groups 1-5 (E. coli suspensions supplemented with 25 mmol / L NH4Br, 0.1 mmol / L H2O2, and 5 mg / L of five different samples). All groups were incubated in pre-sterilized 24-well plates at 37 ℃ for 4 h. After incubation, the bacterial suspensions were serially diluted in sterile 0.9 wt% NaCl solution, and 100 μL was evenly spread onto nutrient agar plates from each well. After incubation at 37 ℃ for 24 h, colony growth was observed and photographed. ImageJ software was used to statistically analyze the colony forming units (CFU) and calculate the antibacterial rate for each group. The results are shown in the appendix. Figure 5 As shown.

[0039] The antibacterial rate of pure CeO2 at 5 mg / L was 45.83%, indicating that it possesses certain antibacterial properties. The antibacterial rate of the 5% Cu-doped sample increased to 56.25%, showing improvement compared to pure CeO2. The antibacterial rate of the 10% Cu-doped sample further increased to 81.25%, demonstrating that copper doping significantly enhanced its antibacterial performance. The antibacterial rate of the 15% Cu-doped sample reached 89.58%, further improving its antibacterial performance. The antibacterial rate of the 20% Cu-doped sample reached the highest at 93.75%. Notably, the sample concentration in this antibacterial experiment was only 5 mg / L, far lower than the test concentrations of other nanoparticles in the literature, demonstrating the material's highly efficient antibacterial potential.

[0040] This antifouling agent, at a dosage of 5 mg / L, achieved an inhibition rate of 93.75% against representative bacterial strains, significantly superior to the 45.83% of the undoped cerium oxide. Its mechanism involves the presence of Br... - Under H₂O₂ conditions, it exhibits halogen oxidase-like activity, continuously generating HOBr and disrupting bacterial signaling and biofilm formation. Since actual seawater environments naturally contain abundant Br... - Therefore, it can still maintain good antibacterial and anti-adhesion properties under the service environment of the coating.

[0041] Because copper exists stably in the cerium oxide lattice as a dopant, the antifouling agent of this invention is not easily dissolved in seawater, thus avoiding the release of large amounts of metal ions and offering long-lasting and environmentally friendly antifouling advantages. Therefore, the antifouling agent is suitable for antifouling protection of various marine engineering structures such as ship hulls, underwater steel structures, and marine pipelines and cables.

Claims

1. A copper-doped cerium oxide antifouling agent, characterized in that... The molecular formula is Cu x Ce 1-x O 2-x , where x is 0.05-0.

2.

2. The preparation method of the copper-doped cerium oxide antifouling agent according to claim 1, characterized in that... Includes the following steps: (1) Dissolve copper salt and cerium salt in deionized water and slowly introduce them into alkaline solution to obtain a mixed solution; (2) The above mixture was stirred continuously at room temperature until it was homogeneous, and the color of the mixture changed from yellow to purple; (3) Transfer to a high-pressure reactor lined with polytetrafluoroethylene and hydrothermally react at 80~100℃ for 12~24h to produce precipitate; (4) The product is purified to obtain copper-doped cerium oxide powder.

3. The preparation method of the copper-doped cerium oxide antifouling agent as described in claim 2, characterized in that... The cerium salt mentioned in step (1) is Ce(NO3)3·6H2O; the copper salt is Cu(NO3)2·3H2O.

4. The preparation method of the copper-doped cerium oxide antifouling agent as described in claim 2, characterized in that... The final concentration of cerium salt in the mixed solution obtained in step (1) is 40-60 mmol / L.

5. The preparation method of the copper-doped cerium oxide antifouling agent as described in claim 2, characterized in that... In step (1), the amount of copper salt is controlled so that the doping ratio in the obtained copper-doped cerium oxide is in the range of 5~20 mol%.

6. The preparation method of the copper-doped cerium oxide antifouling agent as described in claim 2, characterized in that... The alkaline solution mentioned in step (1) is an aqueous solution of sodium hydroxide with a concentration of 0.08-0.12 mol / L.

7. The method for preparing the copper-doped cerium oxide antifouling agent as described in claim 2, characterized in that... The stirring time in step (2) is 0.5~1h.

8. The preparation method of the copper-doped cerium oxide antifouling agent as described in claim 2, characterized in that... In step (3), the hydrothermal reaction temperature is 85-95℃ and the reaction time is 16-20h.

9. The application of the copper-doped cerium oxide antifouling agent of claim 1 as a coating antifouling agent.

10. The application of the copper-doped cerium oxide antifouling agent as described in claim 9 as a coating antifouling agent, characterized in that... The amount of the copper-doped cerium oxide antifouling agent used in the coating ranges from 1 to 5 wt%.

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