Flower-like zinc oxide-cerium composite material and preparation method thereof

Abstract

This invention belongs to the field of nanocomposite materials technology, and relates to a flower-shaped zinc oxide cerium composite material and its preparation method. The flower-shaped zinc oxide cerium composite material is composed of multiple self-assembled nanosheets, all of which are arranged radially, with the widest gap between adjacent nanosheets being 0.2~3 μm. The nanosheets are formed by the composite of zinc oxide and cerium dioxide at the lattice scale. The preparation method is as follows: First, a precursor solution containing soluble zinc salt and soluble cerium salt is prepared. Then, a complexing agent is added to the precursor solution to carry out a complexation reaction to obtain a suspension. Next, tea polyphenols are added to the suspension and uniformly dispersed. The suspension is then transferred to a hydrothermal reactor for hydrothermal reaction. The reaction product is separated, washed, and dried to obtain the flower-shaped zinc oxide cerium composite material. The gaps between the petals of the flower-shaped zinc oxide cerium composite material of this invention match the size of bacteria, greatly improving antibacterial properties and antibacterial durability. The preparation method is simple.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite materials technology, and relates to a flower-shaped zinc oxide cerium composite material and its preparation method. Background Technology

[0002] In recent years, nanocomposites have shown broad application prospects in optics, electronics, catalysis, and antibacterial fields due to their unique physical and chemical properties. Among them, zinc oxide, as an important wide-bandgap (3.2 eV) n-type semiconductor material, possesses excellent optoelectronic properties, antibacterial properties, and environmental friendliness. However, single zinc oxide materials still have some limitations in certain application scenarios.

[0003] For example, CN112915991A discloses a method for preparing a layered, flower-like zinc oxide photocatalyst, which includes steps such as preparing a zinc salt solution, preparing an alkaline solution, and mixing and reacting to prepare zinc oxide. This method provides a way to prepare photocatalytically active zinc oxide materials at room temperature and pressure. The process is simple, highly operable, and suitable for industrial production. Under simulated sunlight, it degrades more than 99.5% of methylene blue within 2 hours, showing broad application prospects. Although the flower-like structure in this patent application increases the specific surface area, it does not solve the problem of improving the photocatalytic oxidation capacity of the flower-like zinc oxide. Furthermore, this patent application does not design a structure specifically for bacterial contact residence time.

[0004] To overcome the limitations of zinc oxide materials, researchers have attempted to combine it with other materials to achieve synergistic effects. For example, CN110357144B discloses a flower-like zinc oxide / ferric oxide microwave absorber, its preparation method, and the microwave absorbing material. This absorber comprises zinc oxide nanorods and ferric oxide particles attached to the surface of the zinc oxide nanorods. This flower-like zinc oxide / ferric oxide microwave absorber, through the flower-like structure of the zinc oxide nanorods, prolongs the propagation path of electromagnetic waves at the zinc oxide nanorod interface, increasing the decay time of electromagnetic energy. However, while the structure of ferric oxide particles coating zinc oxide improves microwave absorption performance, two major limitations restrict its antibacterial properties: first, the ferric oxide covering the zinc oxide surface in this patent application hinders the release of zinc ions; second, iron doping forms heterojunctions on the zinc oxide surface, weakening the photocatalytic oxidation ability of zinc oxide.

[0005] Cerium doping can significantly increase the oxygen vacancy concentration of zinc oxide, promote electron transfer, and improve the photocatalytic oxidation ability of zinc oxide.

[0006] The literature (Antimicrobial Activity of Photoactive Cerium Doped Zinc Oxide, Materials Science & Engineering. [J]. Solid State Phenomena. 2020, 307, 217~222.) discloses that Ce-doped ZnO is more effective against Gram-positive bacteria (Staphylococcus aureus), while exhibiting weaker resistance against Gram-negative bacteria (Escherichia coli). Gram-negative bacteria have a more complex outer membrane structure, which limits the material's penetration and action.

[0007] Therefore, it is of great significance to study a flower-like zinc oxide cerium composite material and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0008] The purpose of this invention is to solve the problems existing in the prior art and to provide a flower-shaped zinc oxide cerium composite material and its preparation method.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A flower-like zinc oxide-cerium composite material is proposed, which is composed of multiple self-assembled nanosheets arranged radially. The widest dimension of the gaps between adjacent nanosheets (i.e., the gaps between petals) is 0.2~3μm. The nanosheets are formed by the composite of zinc oxide (ZnO) and cerium dioxide (CeO2) at the crystal lattice scale. In existing flower-like zinc oxide nanomaterials, the gaps between petals are relatively small, generally not exceeding 0.3μm.

[0011] As a preferred technical solution:

[0012] The above-mentioned flower-shaped zinc oxide cerium composite material has a particle size of 10~50μm and a specific surface area of ​​117~190m². 2 / g.

[0013] The flower-shaped zinc oxide cerium composite material described above has a length (distance from the radiation center to the end) of 200~800nm ​​for a single nanosheet, a width (maximum dimension of a single nanosheet perpendicular to the radiation direction) of 100~400nm, and a thickness of 10~50nm.

[0014] The above-mentioned flower-shaped zinc oxide cerium composite material has a molar ratio of cerium dioxide (CeO2) to zinc oxide (ZnO) of 1:10~100.

[0015] The above-mentioned flower-shaped zinc oxide cerium composite material has an antibacterial rate of >99.99% against both Escherichia coli and Staphylococcus aureus; after being soaked in a water bath at 50±2℃ for 16 hours, the flower-shaped zinc oxide cerium composite material has an antibacterial rate of >99.9% against Escherichia coli and an antibacterial rate of >96% against Staphylococcus aureus.

[0016] The present invention also provides a method for preparing a flower-shaped zinc oxide cerium composite material as described in any of the preceding claims. First, a precursor solution containing soluble zinc salt and soluble cerium salt is prepared. Then, a complexing agent, hexamethylenetetramine (HMT), is added to the precursor solution to carry out a complexation reaction to obtain a suspension. Then, tea polyphenols are added to the suspension and evenly dispersed. The suspension is then transferred to a hydrothermal reactor for hydrothermal reaction. The reaction product is separated, washed, and dried to obtain the flower-shaped zinc oxide cerium composite material.

[0017] Experimental studies have shown that using HMT as a complexing agent can control crystal orientation growth, ultimately forming flower-shaped zinc oxide cerium composite materials; while using EDTA as a complexing agent results in isotropic crystal growth, ultimately forming spherical zinc oxide cerium composite materials; and using citric acid or tartaric acid as complexing agents results in linear crystal growth, which in turn forms nanorod-shaped zinc oxide cerium composite materials.

[0018] The molar ratio of HMT to soluble zinc salt is 1~2:1; the molar ratio of tea polyphenols to soluble zinc salt is 1:38~77; and the molar ratio of cerium ions in soluble cerium salt to zinc ions in soluble zinc salt is 1:10~100.

[0019] As a preferred technical solution:

[0020] The preparation method of the flower-shaped zinc oxide cerium composite material described above uses zinc nitrate hexahydrate (Zn(NO3)2·6H2O) as the soluble zinc salt and cerium nitrate hexahydrate (Ce(NO3)3·6H2O) as the soluble cerium salt.

[0021] In the preparation method of the flower-shaped zinc oxide cerium composite material described above, the concentration of the precursor solution is 26~33wt%.

[0022] In the preparation method of the flower-shaped zinc oxide cerium composite material described above, the complexation reaction temperature is room temperature (25°C) and the time is 30~120 min.

[0023] In the preparation method of the flower-shaped zinc oxide cerium composite material described above, the hydrothermal reaction temperature is 110~180℃ and the time is 4~12h. If the hydrothermal reaction temperature is too high or too low, or the hydrothermal reaction time is too long or too short, the widest size of the gap formed between two adjacent nanosheets will not be 0.2~3μm. For example, if the hydrothermal temperature is too high, the reaction rate is too fast, and the gap between the particles is too small; if the hydrothermal time is too long, the particles will agglomerate to form micron-sized particles.

[0024] Invention principle:

[0025] The flower-like zinc oxide cerium composite material of the present invention has a flower-like structure resembling a "double-petaled chrysanthemum". Unlike traditional flower-like structures, this structure is composed of countless nanosheets that are self-assembled. The nanosheets are arranged radially with abundant pores, unfolding like a mille-feuille. The widest gap between the "petals" is 0.2~3μm in size, while bacteria are usually 0.2~2μm in size. When bacteria fall in, they are physically trapped due to the narrow space and cannot move freely to escape. This greatly increases the contact time between bacteria and the antibacterial agent surface, allowing zinc ions and free radicals sufficient time to kill bacteria, resulting in a significant improvement in antibacterial performance.

[0026] Traditional methods for synthesizing zinc oxide-cerium composites require the introduction of Ce ions (Ce) to address the issue. 3+ radius and Zn 2+ (The differences are large), the lattice distortion is severe, which leads to morphological collapse. The products are irregular particles or short rods, and the agglomeration is severe, resulting in a significant decrease in specific surface area.

[0027] The biomolecule tea polyphenols contain a large number of phenolic hydroxyl groups (-OH), which can selectively adsorb onto specific crystal faces (usually high-energy faces) during crystal growth via hydrogen bonds or coordination bonds, inhibiting the growth rate in that direction and thus inducing crystal growth in other directions, ultimately assembling into heterogeneous structures. In this invention, a complexing agent HMT is first added to a precursor solution containing Zn(NO3)2·6H2O and Ce(NO3)3·6H2O. After reacting to obtain a suspension, tea polyphenols are added for a hydrothermal reaction. By controlling the Ce / Zn molar ratio, the HMT to Zn(NO3)2·6H2O molar ratio, and the proportion of tea polyphenols, under suitable hydrothermal temperature and time conditions, the above-mentioned flower-like zinc oxide cerium composite material with a specific structure was successfully prepared. The molar ratio of HMT to Zn(NO3)2·6H2O should be controlled between 1 and 2:1. If the relative proportion of HMT is too low, the crystal growth rate and the longitudinal growth rate will be similar, resulting in the absence of a lamellar structure, a reduced specific surface area, and decreased antibacterial activity. Furthermore, due to insufficient HMT, the structure of the zinc oxide-cerium composite material is unstable, leading to Ce precipitation after prolonged soaking and decreased antibacterial activity. Conversely, if the relative amount of HMT is too high, it will inhibit the formation of crystal nuclei or even prevent the reaction from proceeding, ultimately resulting in a gel rather than crystals. The Ce / Zn molar ratio should be controlled between 1:10 and 100. A low Ce ratio will result in poor antibacterial activity, while a high Ce ratio will produce irregular particles or short rods with severe agglomeration. The molar ratio of tea polyphenols to Zn(NO3)2·6H2O is 1:38~77. If the proportion of tea polyphenols is too low, the hydrolysis rate will be too fast, the number of crystal nuclei will be large but the growth will be disordered, and small primary particles will easily form and rapidly aggregate. If the proportion of tea polyphenols is too high, the driving force for crystal growth will be insufficient, the crystals will remain at the nanocluster stage, and the product will be fine nanoparticles or fragmented nanosheets.

[0028] The flower-like nano-cerium oxide-based composite material of this invention is synthesized by a hydrothermal method, while existing technologies have disclosed the synthesis of nano-zinc oxide cerium through high-temperature calcination. This method cannot achieve the widest gap size of 0.2~3μm between the "petals" as described in this invention. This is because:

[0029] (1) When the temperature exceeds a certain threshold (e.g., 600~700℃), nanoparticles or micro / nano structures will undergo interparticle fusion and neck growth in order to reduce surface energy. This fusion process leads to material volume shrinkage and structural densification. The micron-sized voids that may have existed in the precursor will shrink rapidly or even disappear completely at high temperatures due to the diffusion and filling of substances into the pores.

[0030] (2) The hydrothermal method can self-assemble a stable three-dimensional flower-like structure during crystal growth. In contrast, in high-temperature muffle furnaces or calcination equipment, heat is transferred through radiation and convection, making it difficult to achieve the uniform molecular-level heating as in hydrothermal reactors. This non-uniformity results in an extremely wide porosity distribution in the final product, making it difficult to concentrate within the narrow range of 0.2~3μm.

[0031] Beneficial effects:

[0032] (1) A flower-shaped zinc oxide cerium composite material of the present invention has a flower-shaped structure of "double-petaled chrysanthemum". The widest gap between the "petals" is 0.2~3μm. This size can physically trap bacteria, thereby greatly increasing the contact time between bacteria and the surface of antibacterial agent, so that zinc ions and free radicals have enough time to kill bacteria (Gram positive bacteria and Gram negative bacteria), resulting in a significant improvement in antibacterial performance.

[0033] (2) The method for preparing a flower-shaped zinc oxide cerium composite material of the present invention, by controlling the molar ratio of Ce / Zn, the molar ratio of HMT to Zn(NO3)2·6H2O and the proportion of tea polyphenols, under suitable hydrothermal temperature and time conditions, successfully prepared a flower-shaped zinc oxide cerium composite material with a specific structure; the method is simple and easy to operate. Attached Figure Description

[0034] Figure 1 The image shown is a 1000x magnified SEM image of the flower-shaped zinc oxide cerium composite material prepared in Example 1.

[0035] Figure 2 The image shown is a 5000x magnified SEM image of the flower-shaped zinc oxide cerium composite material prepared in Example 1.

[0036] Figure 3 SEM image of the zinc oxide-cerium composite material in Comparative Example 1;

[0037] Figure 4 SEM image of the spherical zinc oxide cerium composite material in Comparative Example 5;

[0038] Figure 5 The image shows a SEM image of the nanorod-type zinc oxide cerium composite material of Comparative Example 6. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0040] The test methods involved in the performance indicators in the embodiments and comparative examples of this invention are as follows:

[0041] Antibacterial properties and antibacterial durability testing: Antibacterial properties were tested according to the shaking method in GB / T 21510-2024. The specific steps are as follows:

[0042] (1) Preparation of bacterial culture:

[0043] Standard test strains were selected: Escherichia coli (Shanghai Center for Microbiology Collection, ATCC25922), representing Gram-negative bacteria, and Staphylococcus aureus (Shanghai Center for Microbiology Collection, ATCC6538), representing Gram-positive bacteria.

[0044] Take 24-hour fresh culture from nutrient agar slant of the third to eighth generation of the bacterial strain. Using a 5.0 mL pipette, add 5.0 mL of 0.03 mol / L phosphate buffer (Aladdin, catalog number P397571, pH=7.0) to the slant tube, and repeatedly aspirate and blow to wash off the bacterial growth. Transfer the washed bacterial solution to another sterile test tube, mix well with a shaker, and dilute with 0.03 mol / L phosphate buffer to the appropriate concentration (1×10⁻⁶). 6 (CFU / mL). Bacterial vegetative suspensions should be stored in a refrigerator at 4°C for use and should not be stored for more than 4 hours.

[0045] (2) Sample preparation:

[0046] Test sample: Weigh 0.5g of the antibacterial component (zinc oxide cerium composite material), add 95mL of phosphate buffer containing 0.1wt% Tween-80, mix well, and then add 5mL of the pre-prepared bacterial vegetative suspension from step (1). Prepare a uniform suspension by shaking. The suspension concentration is 1×10⁻⁶. 4 CFU / mL.

[0047] Control sample: Silica powder without antibacterial effect was treated in the same way and served as the control group.

[0048] (3) Shaking contact culture:

[0049] The test sample suspension and the control sample suspension in step (2) were cultured in a constant temperature shaking box at 37℃±1℃ at a speed of 150r / min for 24 hours to ensure that the powder and bacteria were in full contact.

[0050] (4) Viable bacteria count:

[0051] After the shaking contact culture is completed, the suspension is diluted 100 times, and 1 mL of the sample solution is inoculated into sterile petri dishes. Each sample solution is inoculated into two petri dishes in parallel. Nutrient agar medium that has been melted at 45℃ is poured in. After the agar medium solidifies, the plates are turned over and placed in a constant temperature incubator at 37℃±1℃ for viable cell count.

[0052] (5) Observation results:

[0053] The final results were observed after bacterial culture for 48 hours. Colony count was performed according to the method for total colony count determination in GB 4789.2-2022. The average recovered bacterial count (CFU) of the test sample and control sample were calculated, and the antibacterial rate was calculated.

[0054] The gaps formed between two adjacent nanosheets: tested and analyzed using Nano Measure software based on scanning electron microscope (SEM) images.

[0055] The sources of substances in the embodiments and comparative examples of this invention are as follows:

[0056] Zinc nitrate hexahydrate: Aladdin, item number Z111703, purity ≥99%.

[0057] Cerium nitrate hexahydrate: Aladdin, item number C431279, purity ≥99%.

[0058] Hexamethylenetetramine: Aladdin, catalog number H431222, purity ≥98%.

[0059] Tea polyphenols: Aladdin, product number T418534, purity ≥98%.

[0060] EDTA: Aladdin, catalog number E278775, purity ≥98%.

[0061] Citric acid: Aladdin, product number C108869, anhydrous grade, purity ≥99.5%.

[0062] Example 1

[0063] A method for preparing a flower-like zinc oxide cerium composite material, the specific steps of which are as follows:

[0064] (1) Add zinc nitrate hexahydrate and cerium nitrate hexahydrate to water and stir for 30 min to obtain a precursor solution with a concentration of 30.4 wt%;

[0065] The molar ratio of cerium nitrate hexahydrate to zinc nitrate hexahydrate is 1:10.

[0066] (2) Add the complexing agent hexamethylenetetramine to the precursor solution and carry out the complexation reaction for 60 min to obtain a suspension;

[0067] The molar ratio of hexamethylenetetramine to zinc nitrate hexahydrate is 1.2:1.

[0068] (3) Add tea polyphenols to the suspension and disperse them evenly for 40 min. Then transfer it to a hydrothermal reactor and carry out a hydrothermal reaction at 160℃ for 8 h. The reaction product is then centrifuged at 8000 r / min for 15 min, washed with deionized water 3 times, washed with anhydrous ethanol once, and dried at 60℃ for 12 h to obtain flower-shaped zinc oxide cerium composite material.

[0069] The molar ratio of tea polyphenols to zinc nitrate hexahydrate is 1:77.

[0070] like Figures 1-2 As shown, the final flower-shaped zinc oxide-cerium composite material is composed of multiple self-assembled nanosheets, all of which are arranged radially. The average size of the widest gap between adjacent nanosheets is 0.7 μm (gap range: 0.2~1.5 μm). The nanosheets are formed by the composite of zinc oxide and cerium dioxide at the lattice scale. The particle size of the flower-shaped zinc oxide-cerium composite material is 10~30 μm, and the specific surface area is 190 m². 2 / g; the length of a single nanosheet is 400~600nm, the width is 200~400nm, and the thickness is 10~20nm;

[0071] Flower-shaped zinc oxide cerium showed antibacterial rates of >99.99% against both Escherichia coli and Staphylococcus aureus; after soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 99.96%, and the antibacterial rate against Staphylococcus aureus was 96.58%.

[0072] Comparative Example 1

[0073] A method for preparing a zinc oxide cerium composite material is basically the same as in Example 1, except that the molar ratio of hexamethylenetetramine to zinc nitrate hexahydrate in step (2) is 0.5:1.

[0074] The final zinc oxide cerium composite material had an antibacterial rate of 89.93% against Escherichia coli and an antibacterial rate of 76.58% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against both Escherichia coli and Staphylococcus aureus was 0%.

[0075] Comparing Comparative Example 1 and Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 1 are significantly reduced. This is because the relative proportion of hexamethylenetetramine is too low, and the crystal surface growth rate and longitudinal growth rate are similar, thus failing to form a lamellar structure (SEM of the zinc oxide cerium composite material of the comparative example is shown in Figure 1). Figure 3As shown in the figure, the specific surface area decreases, the antibacterial properties decrease, and at the same time, due to insufficient complexing agent, the structure of zinc oxide cerium composite material is unstable. After long-term water immersion, Ce is precipitated, and the antibacterial activity decreases.

[0076] Comparative Example 2

[0077] A method for preparing a zinc oxide cerium composite material is basically the same as in Example 1, except that the molar ratio of hexamethylenetetramine to zinc nitrate hexahydrate in step (2) is 2.2:1.

[0078] Excessive use of hexamethylenetetramine can inhibit the formation of crystal nuclei or even prevent the reaction from proceeding, resulting in a gel instead of crystals, making it impossible to extract the gel for evaluating antibacterial properties.

[0079] Comparative Example 3

[0080] A method for preparing a flower-shaped zinc oxide cerium composite material is basically the same as in Example 1, except that: by adjusting the hydrothermal reaction temperature in step (3) to 200℃ and the reaction time to 2h, the widest gap between two adjacent nanosheets in the prepared flower-shaped zinc oxide cerium composite material is in the range of 0.05~0.2μm.

[0081] The final obtained flower-shaped zinc oxide cerium composite material showed an antibacterial rate of 96.9% against Escherichia coli and 94.1% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 61.6% and the antibacterial rate against Staphylococcus aureus was 54.0%.

[0082] Comparing Comparative Example 3 with Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 3 are significantly reduced. This is because the widest part of the gap formed between two adjacent nanosheets in Comparative Example 3 is small (0.05~0.2μm), making it difficult for bacteria to fall into it. In contrast, the narrow space of 0.2~3μm in this invention allows bacteria to fall into it and be physically trapped, greatly increasing the contact time between bacteria and the surface of the antibacterial agent, giving zinc ions and free radicals enough time to kill bacteria.

[0083] Comparative Example 4

[0084] A method for preparing a flower-shaped zinc oxide cerium composite material is basically the same as in Example 1, except that: by adjusting the hydrothermal reaction temperature in step (3) to 100°C and the reaction time to 48h, the widest gap between two adjacent nanosheets in the prepared flower-shaped zinc oxide cerium composite material is in the range of 3~5μm, and the average particle size of the flower-shaped zinc oxide cerium composite material is 76μm.

[0085] The final obtained flower-shaped zinc oxide cerium composite material showed an antibacterial rate of 97.5% against Escherichia coli and 94.4% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 89.1% and the antibacterial rate against Staphylococcus aureus was 77.6%.

[0086] Comparing Comparative Example 4 and Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 4 are significantly reduced. This is because the narrow space of 0.2~3μm in the present invention can physically trap bacteria, greatly increasing the contact time between bacteria and the surface of the antibacterial agent, allowing zinc ions and free radicals enough time to kill bacteria. In contrast, the average particle size of Comparative Example 4 and the gaps formed between two adjacent nanosheets are too large, significantly larger than the size of bacteria, and cannot trap bacteria.

[0087] Comparative Example 5

[0088] A method for preparing a spherical zinc oxide cerium composite material is basically the same as in Example 1, except that the complexing agent in step (2) is EDTA.

[0089] The resulting spherical zinc oxide cerium composite material exhibited an antibacterial rate of 76.3% against Escherichia coli and 70.7% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 22.6%, while the antibacterial rate against Staphylococcus aureus was 0%.

[0090] Comparing Comparative Example 5 with Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 5 are significantly reduced. This is because EDTA is used as a complexing agent, resulting in isotropic crystal growth, ultimately forming... Figure 4 The spherical zinc oxide cerium composite material shown has a much smaller specific surface area and a much lower number of active sites than the flower-shaped zinc oxide cerium composite material, thus its antibacterial rate and antibacterial durability are significantly reduced.

[0091] Comparative Example 6

[0092] A method for preparing a nanorod-type zinc oxide cerium composite material is basically the same as in Example 1, except that the complexing agent in step (2) is citric acid.

[0093] The final obtained nanorod-shaped zinc oxide cerium composite material showed an antibacterial rate of 74.6% against Escherichia coli and 65.6% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 21.9% and the antibacterial rate against Staphylococcus aureus was 0%.

[0094] Comparing Comparative Example 6 with Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 6 are significantly reduced. This is because citric acid is used as a complexing agent, ultimately forming a complex like... Figure 5 The rod-shaped zinc oxide cerium composite material shown has a much smaller specific surface area and a much lower number of active sites than the flower-shaped zinc oxide cerium composite material, thus its antibacterial rate and antibacterial durability are significantly reduced.

[0095] Comparative Example 7

[0096] A method for preparing a zinc oxide cerium composite material is basically the same as in Example 1, except that the molar ratio of tea polyphenols to zinc nitrate hexahydrate in step (3) is 1:30.

[0097] The final zinc oxide cerium composite material showed an antibacterial rate of 69.3% against Escherichia coli and 68.5% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 30.6% and the antibacterial rate against Staphylococcus aureus was 17.1%.

[0098] Comparing Comparative Example 7 with Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 7 are significantly reduced. This is because the proportion of tea polyphenols is too high, the driving force for crystal growth is insufficient, the crystals remain at the nanocluster stage, and the product is presented as fine nanoparticles or fragmented nanosheets. The specific surface area is much smaller than that of the flower-shaped zinc oxide cerium composite material, so the antibacterial rate and antibacterial durability are significantly reduced.

[0099] Comparative Example 8

[0100] A method for preparing a zinc oxide cerium composite material is basically the same as in Example 1, except that the molar ratio of tea polyphenols to zinc nitrate hexahydrate in step (3) is 1:90.

[0101] The final zinc oxide cerium composite material showed an antibacterial rate of 90.1% against Escherichia coli and 77.9% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 19.1% and the antibacterial rate against Staphylococcus aureus was 0%.

[0102] Comparing Comparative Example 8 with Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 8 are significantly reduced. This is because the proportion of tea polyphenols is low, the hydrolysis rate is too fast, the number of crystal nuclei is large but the growth is disordered, and it is easy to form small primary particles and cause rapid agglomeration. The specific surface area is much smaller than that of the flower-shaped zinc oxide cerium composite material, so the antibacterial rate and antibacterial durability are significantly reduced.

[0103] Comparative Example 9

[0104] A method for preparing a zinc oxide cerium composite material is basically the same as in Example 1, except that the molar ratio of cerium nitrate hexahydrate and zinc nitrate hexahydrate in step (1) is 1:9.

[0105] The final zinc oxide cerium composite material showed an antibacterial rate of 85.4% against Escherichia coli and 80.9% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 48.0% and the antibacterial rate against Staphylococcus aureus was 37.1%.

[0106] Comparing Comparative Example 9 with Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 9 are significantly reduced. This is because the Ce ratio is high and the product is an irregular particle with a smaller specific surface area than the flower-shaped zinc oxide cerium composite material, thus the antibacterial rate and antibacterial durability are significantly reduced.

[0107] Comparative Example 10

[0108] A method for preparing a zinc oxide cerium composite material is basically the same as in Example 1, except that the molar ratio of cerium nitrate hexahydrate and zinc nitrate hexahydrate in step (1) is 1:105.

[0109] The final zinc oxide cerium composite material showed an antibacterial rate of 90.6% against Escherichia coli and 89.9% against Staphylococcus aureus. After soaking in a water bath at 50±2℃ for 16 hours, the antibacterial rate against Escherichia coli was 57.5% and the antibacterial rate against Staphylococcus aureus was 39.0%.

[0110] Comparing Comparative Example 10 with Example 1, it can be found that the antibacterial rate and antibacterial durability of Comparative Example 10 are significantly reduced. This is because the introduction of cerium forms an intermediate energy level, which reduces the band gap, promotes electron transfer, and improves photocatalytic oxidation ability. The low Ce ratio leads to a weak synergistic effect, thus the antibacterial rate and antibacterial durability are significantly reduced.

[0111] Example 2

[0112] A method for preparing a flower-like zinc oxide cerium composite material, the specific steps of which are as follows:

[0113] (1) Add zinc nitrate hexahydrate and cerium nitrate hexahydrate to water and stir for 30 min to obtain a precursor solution with a concentration of 28.7 wt%;

[0114] The molar ratio of cerium nitrate hexahydrate to zinc nitrate hexahydrate is 1:50.

[0115] (2) Add the complexing agent hexamethylenetetramine to the precursor solution and carry out the complexation reaction for 60 min to obtain a suspension;

[0116] The molar ratio of hexamethylenetetramine to zinc nitrate hexahydrate is 1.5:1.

[0117] (3) Add tea polyphenols to the suspension and disperse them evenly for 40 min. Then transfer it to a hydrothermal reactor and carry out a hydrothermal reaction at 130℃ for 10 h. The reaction product is then centrifuged at 8000 r / min for 15 min, washed with deionized water 3 times, washed with anhydrous ethanol once, and dried at 60℃ for 12 h to obtain flower-shaped zinc oxide cerium composite material.

[0118] The molar ratio of tea polyphenols to zinc nitrate hexahydrate is 1:38.

[0119] The resulting flower-shaped zinc oxide-cerium composite material is composed of multiple self-assembled nanosheets arranged radially. The widest gap between adjacent nanosheets ranges from 0.3 to 2.2 μm, with an average size of 1.3 μm. The nanosheets are formed by the lattice-scale composite of zinc oxide and cerium dioxide. The particle size of the flower-shaped zinc oxide-cerium composite material is 10–30 μm, and its specific surface area is 167 m². 2 / g; the length of a single nanosheet is 300~500nm, the width is 100~200nm, and the thickness is 15~30nm;

[0120] The flower-shaped zinc oxide cerium composite material showed antibacterial rates of >99.99% against both Escherichia coli and Staphylococcus aureus; after soaking in a water bath at 50±2℃ for 16h, the antibacterial rate against Escherichia coli was >99.99%, and the antibacterial rate against Staphylococcus aureus was 96.44%.

[0121] Example 3

[0122] A method for preparing a flower-like zinc oxide cerium composite material, the specific steps of which are as follows:

[0123] (1) Add zinc nitrate hexahydrate and cerium nitrate hexahydrate to water and stir for 30 min to obtain a precursor solution with a concentration of 29.3 wt%;

[0124] The molar ratio of cerium nitrate hexahydrate to zinc nitrate hexahydrate is 1:20.

[0125] (2) Add the complexing agent hexamethylenetetramine to the precursor solution and carry out the complexation reaction for 60 min to obtain a suspension;

[0126] The molar ratio of hexamethylenetetramine to zinc nitrate hexahydrate is 1.6:1.

[0127] (3) After adding tea polyphenols to the suspension and dispersing them evenly for 40 min, the mixture was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 180°C for 4 h. The reaction product was then centrifuged at 8000 r / min for 15 min, washed with deionized water 3 times, washed with anhydrous ethanol once, and dried at 60°C for 12 h to obtain the flower-shaped zinc oxide cerium composite material.

[0128] The molar ratio of tea polyphenols to zinc nitrate hexahydrate is 1:38.

[0129] The resulting flower-like zinc oxide-cerium composite material was formed by the self-assembly of multiple nanosheets. All nanosheets were arranged radially, and the widest gap between adjacent nanosheets ranged from 0.6 to 2.8 μm, with an average size of 1.7 μm. The nanosheets were formed by the composite of zinc oxide and cerium dioxide at the lattice scale. The particle size of the flower-like zinc oxide-cerium composite material was 30–50 μm, and the specific surface area was 169 m². 2 / g; the length of a single nanosheet is 200~500nm, the width is 100~300nm, and the thickness is 10~30nm;

[0130] The flower-shaped zinc oxide cerium composite material showed antibacterial rates of >99.99% against both Escherichia coli and Staphylococcus aureus; after soaking in a water bath at 50±2℃ for 16h, the antibacterial rate against Escherichia coli was >99.99%, and the antibacterial rate against Staphylococcus aureus was 97.95%.

[0131] Example 4

[0132] A method for preparing a flower-like zinc oxide cerium composite material, the specific steps of which are as follows:

[0133] (1) Add zinc nitrate hexahydrate and cerium nitrate hexahydrate to water and stir for 30 min to obtain a precursor solution with a concentration of 26.3 wt%;

[0134] The molar ratio of cerium nitrate hexahydrate to zinc nitrate hexahydrate is 1:80.

[0135] (2) Add the complexing agent hexamethylenetetramine to the precursor solution and carry out the complexation reaction for 30 min to obtain a suspension;

[0136] The molar ratio of hexamethylenetetramine to zinc nitrate hexahydrate is 1:1.

[0137] (3) After adding tea polyphenols to the suspension and dispersing them evenly for 40 min, the mixture was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 110°C for 12 h. The reaction product was then centrifuged at 8000 r / min for 15 min, washed with deionized water three times, washed with anhydrous ethanol once, and dried at 60°C for 12 h to obtain the flower-shaped zinc oxide cerium composite material.

[0138] The molar ratio of tea polyphenols to zinc nitrate hexahydrate is 1:77.

[0139] The resulting flower-shaped zinc oxide-cerium composite material was formed by the self-assembly of multiple nanosheets. All nanosheets were arranged radially, and the widest gap between adjacent nanosheets ranged from 0.5 to 2.5 μm, with an average size of 1.4 μm. The nanosheets were formed by the composite of zinc oxide and cerium dioxide at the lattice scale. The particle size of the flower-shaped zinc oxide-cerium composite material was 20–40 μm, and the specific surface area was 117 m². 2 / g; the length of a single nanosheet is 600~800nm, the width is 200~400nm, and the thickness is 20~50nm;

[0140] The flower-shaped zinc oxide cerium composite material showed antibacterial rates of >99.99% against both Escherichia coli and Staphylococcus aureus; after soaking in a water bath at 50±2℃ for 16h, the antibacterial rate against Escherichia coli was >99.99%, and the antibacterial rate against Staphylococcus aureus was 98.69%.

[0141] Example 5

[0142] A method for preparing a flower-like zinc oxide cerium composite material, the specific steps of which are as follows:

[0143] (1) Add zinc nitrate hexahydrate and cerium nitrate hexahydrate to water and stir for 30 min to obtain a precursor solution with a concentration of 32.5 wt%;

[0144] The molar ratio of cerium nitrate hexahydrate to zinc nitrate hexahydrate is 1:100.

[0145] (2) Add the complexing agent hexamethylenetetramine to the precursor solution and carry out the complexation reaction for 120 min to obtain a suspension;

[0146] The molar ratio of hexamethylenetetramine to zinc nitrate hexahydrate is 2:1.

[0147] (3) After adding tea polyphenols to the suspension and dispersing them evenly for 40 min, the mixture was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 150°C for 9 h. The reaction product was then centrifuged at 8000 r / min for 15 min, washed with deionized water 3 times, washed with anhydrous ethanol once, and dried at 60°C for 12 h to obtain the flower-shaped zinc oxide cerium composite material.

[0148] The molar ratio of tea polyphenols to zinc nitrate hexahydrate is 1:38.

[0149] The resulting flower-like zinc oxide-cerium composite material was formed by the self-assembly of multiple nanosheets. All nanosheets were arranged radially, and the widest gap between adjacent nanosheets ranged from 1.4 to 2.9 μm, with an average size of 2.1 μm. The nanosheets were formed by the composite of zinc oxide and cerium dioxide at the lattice scale. The particle size of the flower-like zinc oxide-cerium composite material was 20–40 μm, and the specific surface area was 123 m².2 / g; the length of a single nanosheet is 300~700nm, the width is 500~800nm, and the thickness is 20~30nm;

[0150] The flower-shaped zinc oxide cerium composite material showed antibacterial rates of >99.99% against both Escherichia coli and Staphylococcus aureus; after soaking in a water bath at 50±2℃ for 16h, the antibacterial rate against Escherichia coli was >99.99%, and the antibacterial rate against Staphylococcus aureus was 99.76%.

Claims

1. A flower-shaped zinc oxide cerium composite material, characterized in that: It is composed of multiple self-assembled nanosheets, all of which are arranged radially, and the widest gap between two adjacent nanosheets is 0.2~3μm; the nanosheets are formed by the composite of zinc oxide and cerium dioxide at the lattice scale.

2. The flower-shaped zinc oxide cerium composite material according to claim 1, characterized in that, The flower-like zinc oxide cerium composite material has a particle size of 10~50μm and a specific surface area of ​​117~190m². 2 / g.

3. The flower-shaped zinc oxide cerium composite material according to claim 1, characterized in that, The length of a single nanosheet is 200~800nm, the width is 100~400nm, and the thickness is 10~50nm.

4. A flower-shaped zinc oxide cerium composite material according to any one of claims 1 to 3, characterized in that, The flower-shaped zinc oxide cerium composite material exhibits antibacterial rates of >99.99% against both Escherichia coli and Staphylococcus aureus. After immersion in a water bath at 50±2℃ for 16 hours, the antibacterial rate of the flower-shaped zinc oxide cerium composite material against Escherichia coli is >99.9%, and the antibacterial rate against Staphylococcus aureus is >96%.

5. A method for preparing a flower-like zinc oxide cerium composite material according to any one of claims 1 to 4, characterized in that: First, a precursor solution containing soluble zinc salt and soluble cerium salt is prepared. Then, a complexing agent, hexamethylenetetramine, is added to the precursor solution to carry out a complexation reaction to obtain a suspension. Tea polyphenols are then added to the suspension and evenly dispersed. The suspension is then transferred to a hydrothermal reactor for hydrothermal reaction. The reaction product is separated, washed, and dried to obtain a flower-shaped zinc oxide cerium composite material. The molar ratio of hexamethylenetetramine to soluble zinc salt is 1~2:1; the molar ratio of tea polyphenols to soluble zinc salt is 1:38~77; and the molar ratio of cerium ions in soluble cerium salt to zinc ions in soluble zinc salt is 1:10~100.

6. The method for preparing a flower-like zinc oxide cerium composite material according to claim 5, characterized in that, The soluble zinc salt is zinc nitrate hexahydrate, and the soluble cerium salt is cerium nitrate hexahydrate.

7. The method for preparing a flower-like zinc oxide cerium composite material according to claim 5, characterized in that, The concentration of the precursor solution is 26~33wt%.

8. The method for preparing a flower-like zinc oxide cerium composite material according to claim 5, characterized in that, The complexation reaction takes 30 to 120 minutes.

9. The method for preparing a flower-like zinc oxide cerium composite material according to claim 5, characterized in that, The hydrothermal reaction temperature is 110~180℃, and the time is 4~12h.

Images