Preparation method of micro-nano structure cuprous oxide polycrystal particles

Abstract

The present application relates to a kind of preparation methods of micro-nano structure cuprous oxide polycrystalline particles, belong to cuprous oxide polycrystalline preparation technical field, first to the aqueous solution of divalent copper salt drop adds aqueous solution of organic amine, after stirring reaction, again drop adds reducing agent solution to reaction liquid, continue stirring reaction, and the product is prepared by centrifugation and drying to reaction liquid;The average particle size of micro-nano structure cuprous oxide polycrystalline particle is 1~2.3 μm, and micro-nano structure cuprous oxide polycrystalline particle is formed by small size cuprous oxide crystal intergrowth;The grain size of small size cuprous oxide crystal that constitutes micro-nano structure cuprous oxide polycrystalline particle is determined by the type of organic amine, and the grain size of small size cuprous oxide crystal is 40~600 nm, and organic amine is one or more of aniline, furfurylamine, benzylamine, phenethylamine and n-butylamine.The crystal grain diameter of polycrystalline particle formed by the method can be controlled and adjusted in the range of 40~600 nm by selecting different organic amine.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cuprous oxide polycrystalline particle preparation and relates to a preparation method of micro-nano structures. BACKGROUND

[0002] As a relatively common inorganic material, cuprous oxide powder is widely used in antibacterial, coating, ship antifouling and other fields. At present, liquid phase reduction method is one of the most common chemical methods for batch preparation of cuprous oxide powder. The related method for synthesizing cuprous oxide particles under normal pressure through liquid phase reduction method at near room temperature has been widely studied, and a large number of literatures have been produced, such as document 1 (J. Am. Chem. Soc., 2024, 146(14): 9665-9678.), document 2 (ACSSustainable Chem. Eng., 2023, 11(44): 15931-15940.), document 3 (Appl Organomet Chem., 2024, 38(8)) and document 4 (ACS Sens., 2019, 4(11): 3051-3055.). However, the cuprous oxide particles synthesized in these documents are generally simple morphologies such as cubic, polyhedral or spherical, and the particles do not have complex structure composition, which cannot meet the use requirements of low agglomeration and large specific surface area of the particles at the same time, and is not conducive to the performance expression of the material.

[0003] Literature 5 (Small, 2023, 19(26), 2300394.) and literature 6 (Chem. Rev., 2016, 116(18): 10983-11060.) both mention that the construction of micro-nano structures can make materials have high specific surface area and high catalytic activity of nanomaterials, and the characteristics of large size materials not easy to agglomerate. By constructing nanometer-sized units on the surface of micrometer-sized particles or performing precise morphology modification, the nanometer unit with special effect can be connected with the macro particle itself, so that the material has certain characteristics of nanometer-sized materials while having a larger scale, such as structural color phenomenon, surface plasmon resonance (SPR, surface plasmon resonance) of nanoparticles, etc. For some applications in some fields, the construction of micro-nano structures also has other effects, such as literature 7 (Adv. Funct. Mater., 2021, 31(12), 2008352.) mentioned that cuprous oxide can be precisely fitted to the surface of microorganisms through the constructed micro-nano structure, thereby maximizing the role of contact killing viruses. In addition, the performance of many powder materials is closely related to the specific surface area of the powder material. The larger the specific surface area, the better the performance of the material. By constructing micro-nano structures, the particles can obtain a larger specific surface area through the nanometer-sized units on the surface of the particles, and due to the larger particle size (micron or near micron), the particles are not easy to agglomerate compared with nanoparticles, and have better dispersibility when used. In summary, the construction of micro-nano structure cuprous oxide spherical particles with nanometer-sized units has practical significance.

[0004] In the current patents for synthesizing micro-nano structure cuprous oxide particles, patent CN104261457A synthesizes polyhedral cuprous oxide particles with smooth surfaces, and the morphology includes hexahedron, octahedron, polyhedron, and sphere, without assembling or modifying structures of small-sized units. Patent CN111285394B uses polyhydric alcohol to dissolve copper source, which has high synthesis cost and is not conducive to the post-treatment of waste liquid. Patent CN113083239B has a complex reaction system, and the raw materials include wood pulp, TEMPO, sodium carbonate, sodium citrate, copper sulfate pentahydrate, sodium hypochlorite, and sodium bromide, which is not conducive to cost reduction and synthesis process simplification due to too many reaction raw materials. Patents CN104772142A and literature 8 (CrystEngComm, 2012, 14: 278-285.) both obtained micro-nano structure cuprous oxide spheres, but need to be synthesized by high-temperature and high-pressure hydrothermal or solvothermal reaction, which has harsh conditions and certain danger.

[0005] The current size control of cuprous oxide particles mainly aims at the macroscopic size of the particles. For example, by controlling the concentration of copper salt and using acid etching, different particle sizes of cuprous oxide spheres were obtained in document 9 (Part. Part. Syst. Charact., 2020, 37, 2000106.), and it was found in document 10 (Electroanalysis, 2017, 29: 2773-2779.) that the introduction of Au would greatly change the particle size of cuprous oxide macroscopic particles. However, there is currently no relevant literature on the multi-level controllable regulation of the size of small-sized crystals constituting cuprous oxide polycrystalline particles or small-sized particles constituting cuprous oxide assembled particles. It is speculated that this is because the synthesis of current micro-nano structure cuprous oxide generally needs to use macromolecular dispersants, such as patents CN108680625A, CN106493381B, CN104445358B, document 11 (Adv. Mater., 2024, 36, 2313212.) and document 12 (Chemical Journal, 2009, 67(14): 1591-1596.), which use macromolecular or long carbon chain dispersants such as polyethylene glycol, polyvinylpyrrolidone, sodium oleate, cetyltrimethylammonium bromide, sodium dodecyl sulfate, etc. On the one hand, these dispersants are easy to remain in the product, affecting the purity and increasing the synthesis cost, on the other hand, they actually play the role of a template to limit the growth size of individual cuprous oxide crystal particles, so that cuprous oxide particles exist in the form of small-sized particles and further agglomerate to form micro-nano structures, therefore, changing the concentration of copper salt and other means cannot greatly change the size of small crystal grains, only the number of small crystal grains increases, leading to the increase of the size of macroscopic particles. Due to the large difference in chemical composition and structure between various macromolecular dispersants, their functional group types, branched structures, aqueous solution viscosities, acid and base properties are all different, and in the synthesis system, it is impossible to simply replace the macromolecular dispersant to control the size of small-sized particles.

[0006] In the current other patents or papers of synthesizing cuprous oxide polycrystal, CN101905899A synthesizes cuprous oxide polycrystal, but only describes that the size of the polycrystal is 100-400 nm, and does not mention the size of the cuprous oxide crystal constituting the polycrystal; CN101041456A synthesizes cuprous oxide hollow sub-micro-spheres formed by 11-22 nm cuprous oxide nanoparticles self-assembled; CN107473258A synthesizes cuprous oxide polycrystal composed of 10-20 nm cuprous oxide nanocrystals; CN101778799A synthesizes spherical assembly particles formed by 1-100 nm ultra-fine cuprous oxide particles; CN109485084A synthesizes cuprous oxide cubes or microspheres assembled by cuprous oxide nanoparticles; and document 13 (Small, 2022, 18(15), 2107422.) synthesizes cuprous oxide hollow assembly shell, but the above all do not contain the description related to the size regulation of the small-size unit constituting the cuprous oxide particles. In addition, patent CN105905936A introduces two different morphologies of cuprous oxide nanocrystal assemblies, CNA-1 and CNA-2, and the sizes of the nanocrystals constituting the particles are 32 nm and 10 nm respectively, but do not include a multi-level controllable regulation method of a larger span of crystal size from nanometer to micrometer. In addition, document 12 synthesizes cuprous oxide hollow sub-micro-spheres with a particle size of 200 nm, but only the size of the microsphere particles increases in the reaction process, and the size of the surface particles changes little from 10 nm to 11 nm.

[0007] Therefore, it is of great significance to study a preparation method of micro-nano structure cuprous oxide polycrystal particles to solve the problems in the prior art. SUMMARY

[0008] The purpose of the present application is to solve the problems in the prior art and provide a preparation method of micro-nano structure cuprous oxide polycrystal particles.

[0009] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0010] A preparation method of micro-nano structure cuprous oxide polycrystal particles, first, an organic amine aqueous solution is added dropwise into an aqueous solution of divalent copper salt, and then a reducing agent solution is added dropwise into the reaction solution after stirring reaction, and the reaction solution is centrifuged and dried to obtain micro-nano structure cuprous oxide polycrystal particles;

[0011] The micro-nano structure cuprous oxide polycrystal particles are in a near-spherical morphology on a macroscopic scale, the average particle size of the micro-nano structure cuprous oxide polycrystal particles is 1-2.3 μm, and the micro-nano structure cuprous oxide polycrystal particles are formed by the co-growth of small-size cuprous oxide crystals, and the small-size cuprous oxide crystals are in a near-spherical truncated octahedral morphology;

[0012] The grain size of the small-size cuprous oxide crystal constituting the micro-nano structure cuprous oxide polycrystal particle is determined by the type of the organic amine, and the selected organic amine has a molecular weight of less than 200 and contains only one amino group in the main chain. The organic amine is one or more of aniline, furfurylamine, benzylamine, phenethylamine and n-butylamine. The grain size of the small-size cuprous oxide crystal (calculated by XRD spectrum) is 40-600 nm.

[0013] As a preferred technical solution:

[0014] The preparation method of the micro-nano structure cuprous oxide polycrystal particle is as follows:

[0015] (1) Under mechanical stirring at a speed of 200-500 rpm, an aqueous solution of the organic amine is slowly added to a uniform and stable aqueous solution of the divalent copper salt at a rate of 1-10 mL / min. After the addition is completed, the stirring reaction is continued for 0.5-5 h to obtain a mixed solution;

[0016] (2) Under mechanical stirring at a speed of 200-500 rpm, an aqueous solution of the reducing agent is slowly added to the mixed solution obtained in step (1) at a rate of 1.25-7.5 mL / min. After the addition is completed, the stirring reaction is continued for 0.25-3 h until the color of the reaction solution tends to be stable. The reaction product is collected by centrifugal treatment of the reaction solution;

[0017] (3) The solid component obtained in step (3) is washed with deionized water and ethanol, and vacuum dried in a vacuum oven at 50-80℃ for 6-12 h to obtain the micro-nano structure cuprous oxide polycrystal particle.

[0018] In steps (1) and (2) of the preparation method of the micro-nano structure cuprous oxide polycrystal particle, the reaction temperature is 20-80℃, and the reaction pressure is 0.1 MPa.

[0019] In step (1) of the preparation method of the micro-nano structure cuprous oxide polycrystal particle, the divalent copper salt is one or more of copper acetate, copper sulfate, copper nitrate and copper chloride, the concentration of the aqueous solution of the divalent copper salt is 0.1-1.2 M, and the concentration of the aqueous solution of the organic amine is 0.24-9.6 M.

[0020] In step (2) of the preparation method of the micro-nano structure cuprous oxide polycrystal particle, the reducing agent is one of hydrazine hydrate, ascorbic acid, glucose and sodium sulfite, and the concentration of the aqueous solution of the reducing agent is 0.07-2.0 M.

[0021] In the preparation method of the micro-nano structure cuprous oxide polycrystal particle, the molar ratio of the divalent copper salt, the organic amine and the reducing agent is 1:0.6-2:0.525-2.

[0022] The purity (i.e. the mass proportion of the micro-nano structure cuprous oxide polycrystalline particles in the product) of the micro-nano structure cuprous oxide polycrystalline particles prepared by the method is greater than 95%.

[0023] The thermal weight loss of the micro-nano structure cuprous oxide polycrystalline particles prepared by the method is less than 4%.

[0024] Principle of the application:

[0025] The small molecule amine is used as a raw material in the application, which actually replaces the functions of the alkali and the dispersant / template agent in the prior art in one step. The size of the nanocrystals constituting the cuprous oxide polycrystalline particles can be accurately controlled on a larger scale by adjusting the steric hindrance of the small molecule amine. Since the molecular weight of the amine is small, the amine is easily removed from the product by washing or heating compared to the macromolecular template agent, without affecting the purity and thermal stability of the product.

[0026] The amino group of the organic amine forms a coordination bond with the divalent copper ion to form a planar ion structure similar to tetraamminecopper in the solution. If the small molecule amine contains an aromatic ring, the large steric hindrance of the aromatic ring connected to the amino group forms a dense protection to the copper ion in four directions, limiting the attack of the reducing agent on the copper ion, thereby slowing down the growth rate of the cuprous oxide crystal, forming small-sized crystal grains, and achieving the purpose of controlling the grain size. There are many types of primary amine small molecule units with similar chemical composition and structure. When a large-sized aromatic ring exists in the molecule, the shorter the carbon chain connected between the aromatic ring and the amino group, the closer the aromatic ring to the copper ion, the stronger the protection of the copper ion, the smaller the size of the crystal grain, and vice versa. When the small molecule amine does not have an aromatic ring and only has an alkane chain, the steric hindrance is the smallest, and the central copper ion is the weakest in protection, and accordingly, it is the most vulnerable to attack by the reducing agent to grow into a larger size. In summary, the size of the crystal constituting the particle can be accurately controlled by selecting a small molecule amine with a specific steric hindance during synthesis, so that the size of the micro-nano structure cuprous oxide polycrystalline particle can be controlled in multiple levels.

[0027] The preparation method of the micro-nano structure cuprous oxide polycrystalline particles provided by the application can control the particle size of the micro-nano structure cuprous oxide polycrystalline particles in the range of 40-600 nm by selecting different small molecule amines when other conditions remain unchanged. Specifically, the size of the crystal in the particles obtained in the order of aniline, furfurylamine, benzylamine, phenethylamine and n-butylamine gradually increases. The principle is as follows:

[0028] When the small molecule amine enters the aqueous solution of the divalent copper salt, part of the small molecule amine is coordinated with the divalent copper ion, specifically, four amine molecules are used as ligands to form a complex ion similar to the structure of tetraamminecopper, and the reaction equation is as follows:

[0029] Cu 2+ +4 R-NH2→[Cu(H2N-R)4] 2+ ;

[0030] In the formula, R represents the group connected to the amino group in the five small molecule amines;

[0031] The small molecule amines such as aniline, furfurylamine, benzylamine, phenethylamine and n-butylamine have different steric hindrances after being coordinated with the copper ion.

[0032] Among the small molecule amines containing aromatic rings, aniline has the shortest carbon chain length, and the benzene ring is directly connected to the amino group, which causes the copper at the center of the complex ion to be close to the surrounding four benzene rings, forming a structure in which the four benzene rings tightly wrap the copper ion, and the steric hindrance formed in the five small molecule amines is the largest; the carbon chain length of furfurylamine and benzylamine is the second, and the aromatic ring is separated from the amino group by one carbon, which causes a certain distance between the four larger aromatic rings and the copper, and the wrapping of the aromatic ring on the copper is not as tight as that of aniline, and there is a certain exposed space. Since the furan ring of furfurylamine is slightly smaller than the benzene ring of benzylamine, the steric hindrance of furfurylamine on the copper ion is also slightly smaller than that of benzylamine; among the small molecule amines containing aromatic rings, phenethylamine has the longest carbon chain length, and the aromatic ring is separated from the amino group by two carbons, which causes the relatively large aromatic ring to be as far away from the copper ion as possible, and the protective effect on the copper ion is smaller; compared with the small molecule amines containing aromatic rings, n-butylamine has only one carbon chain, and after the amino group is connected to the copper ion, the steric hindrance formed is much smaller than that of the other four amines with large volume aromatic rings, and the copper ion is fully exposed and most easily contacts the outside. Therefore, the order of the steric hindrance intensity of the five small molecule amines after being coordinated with the copper ion is: aniline > furfurylamine > benzylamine > phenethylamine > n-butylamine, and the corresponding small molecule amine covering intensity on the copper ion is shown in Figure 1 . It can be seen that the covering degree of the amine on the copper in the complex ion decreases in turn.

[0033] Furthermore, during the reduction reaction, due to the varying coating strengths of the four amine complexes on copper ions, after crystal nucleation, the more strongly coated complexes offer better protection for divalent copper, making them the least likely to be attacked by the reducing agent. This hinders crystal growth after nucleation, leading to re-nucleation and growth into smaller grains. Conversely, the weakly coated complexes allow the reducing agent to more easily attack the divalent copper at their centers, facilitating a smoother reduction reaction. Following nucleation, the crystal size rapidly increases with the reduction reaction, eventually growing into large grains. This allows for precise control of grain size by adjusting steric hindrance. Ultimately, crystals of different sizes will aggregate under the driving force of decreasing surface energy, further co-growing to form micro / nano-structured polycrystalline cuprous oxide particles.

[0034] Beneficial effects:

[0035] (1) The present invention provides a method for preparing micro-nano structured cuprous oxide polycrystalline particles by replacing the high molecular weight dispersant and inorganic base in the existing process with a small molecule amine in one step. The small molecule amine has a simple molecular structure and has the advantages of low price, good water solubility and low toxicity. At the same time, due to its low molecular weight, it is easy to remove it from the product as much as possible by washing with water and heating, thereby ensuring that the final cuprous oxide powder product has high purity. In addition, by controlling the type of small molecule amine, the size of the small crystals constituting the polycrystalline particles can be controlled in the range of 40~600 nm. Specifically, the size of the small crystals constituting the micro-nano structured cuprous oxide polycrystalline particles gradually increases in the order of aniline, furfurylamine, benzylamine, phenethylamine and n-butylamine, thereby obtaining cuprous oxide polycrystalline particles with gradient changes in morphology.

[0036] (2) The present invention provides a method for preparing polycrystalline cuprous oxide micro-nano structured particles. The crystal particle size of the polycrystalline particles can be controlled and adjusted in the range of 40~600 nm by selecting different organic amines. It has the advantages of mild reaction conditions, simple raw material types, low synthesis cost, and controllable product morphology.

[0037] (3) The method for preparing micro-nano structured cuprous oxide polycrystalline particles of the present invention is carried out at normal pressure and near room temperature, which is mild and safe; there are only three types of raw materials for the reaction, and the one-pot synthesis process is simple and controllable. Attached Figure Description

[0038] Figure 1 The reaction equations are for the coordination of five small molecule amines—aniline, furfurylamine, benzylamine, phenethylamine, and n-butylamine—with copper ions.

[0039] Figure 2 SEM images of micro / nano structured cuprous oxide particles obtained in Example 1 at different scales; where the scale on the left is 1 μm and the scale on the right is 10 μm.

[0040] Figure 3 SEM images of micro-nano structured cuprous oxide particles obtained in Example 2 at different scales; wherein the left image scale is 1 μm and the right image scale is 10 μm;

[0041] Figure 4 SEM images of micro-nano structured cuprous oxide particles obtained in Example 3 at different scales; wherein the left image scale is 1 μm and the right image scale is 10 μm;

[0042] Figure 5 SEM images of micro-nano structured cuprous oxide particles obtained in Example 4 at different scales; wherein the left image scale is 1 μm and the right image scale is 10 μm;

[0043] Figure 6 SEM images of micro-nano structured cuprous oxide particles obtained in Example 5 at different scales; wherein the left image scale is 1 μm and the right image scale is 10 μm;

[0044] Figure 7 SEM images of micro-nano structured cuprous oxide particles obtained in Comparative Example 1 at different scales; wherein the left image scale is 1 μm and the right image scale is 10 μm;

[0045] Figure 8 Thermogravimetric curves of Example 1, Example 2 and Example 3;

[0046] Figure 9 Bar chart of antiviral rates of commercially available 100 nm cuprous oxide, commercially available 1000 nm cuprous oxide, Example 1 and Example 3;

[0047] Figure 10 XRD patterns of micro-nano structured cuprous oxide particles obtained in Examples 1-5;

[0048] Figure 11 Structural interpretation of Example 3, wherein the left image is an SEM image of micro-nano structured cuprous oxide particles obtained at a scale of 1 μm and the right image is a typical truncated octahedral grain of cuprous oxide. DETAILED DESCRIPTION

[0049] The application will be further described with reference to the following specific examples. It should be understood that these examples are intended to illustrate the application and are not intended to limit the scope of the application. Furthermore, since modifications to the application will occur to those skilled in the art, it is intended to cover any and all such modifications as fall within the scope of the appended claims.

[0050] The test methods involved in the performance indicators of the present application are as follows:

[0051] Scanning electron microscope picture: Regulus 8230 field emission scanning electron microscope (HITACHI, Japan) was used.

[0052] Thermogravimetric curve: TG209F1 thermogravimetric analyzer (NETZSCH, Germany) was used under nitrogen atmosphere, with a purge gas rate of 40 mL / min, a protective gas rate of 20 mL / min, a heating rate of 10°C / min, and a test actual range of 30-700°C.

[0053] XRD pattern: D8 Advance in-situ electrochemical X-ray diffractometer (Bruker, USA) was used for testing, with a copper target, a test step of 0.01°, and a test 2θ range of 10°-90°.

[0054] Antiviral rate (virus inhibition rate): The test was performed according to the ISO 18184-2019 standard, and the test virus was HCoV-OC43 virus.

[0055] Commercially available 100 nm grade cuprous oxide was purchased from Beijing Zhongke Keyou Technology Co., Ltd., and nano cuprous oxide powder (spherical, 100 nm).

[0056] Commercially available 1000 nm grade cuprous oxide was purchased from Anhui Kenrun Nanometer Technology Co., Ltd.

[0057] Example 1

[0058] A method for preparing a micro-nano structure cuprous oxide polycrystalline particle, the specific steps are as follows:

[0059] (1) Under the conditions of mechanical stirring at a speed of 500 rpm, a reaction temperature of 60°C, and a reaction pressure of 0.1 MPa, a 1.8 M aniline aqueous solution was slowly added to a uniform and stable 0.3 M copper nitrate aqueous solution, the addition rate was 5 mL / min, after the addition was completed, the stirring reaction was continued for 3 h, and a mixed solution was obtained;

[0060] (2) Under the conditions of mechanical stirring at a speed of 500 rpm, a reaction temperature of 60°C, and a reaction pressure of 0.1 MPa, a 0.8 M glucose aqueous solution was slowly added to the mixed solution obtained in step (1), the addition rate was 2.0 mL / min, after the addition was completed, the stirring reaction was continued for 2 h, and the reaction product was collected by centrifugal treatment of the reaction solution;

[0061] The molar ratio of copper nitrate, aniline and glucose is 1:1.5:2;

[0062] (3) The solid component obtained in step (3) is washed with deionized water and ethanol, vacuum dried in a vacuum oven at 60°C for 10 h, and micro-nano structured cuprous oxide polycrystalline particles are obtained.

[0063] As shown in Figure 2 , the average particle size of the finally prepared micro-nano structured cuprous oxide polycrystalline particles is 1.0 μm, and the micro-nano structured cuprous oxide polycrystalline particles are formed by the co-growth of small-size cuprous oxide crystals with a grain size of 40 nm; the purity of the micro-nano structured cuprous oxide polycrystalline particles is 95.6%; as shown in Figure 8 , the thermal weight loss of the micro-nano structured cuprous oxide polycrystalline particles is 3.59%; and the anti-virus rate against HCoV-OC43 virus within 3 min is 99.07% according to the ISO 18184-2019 standard test, which has good anti-virus effect.

[0064] Example 2

[0065] A preparation method of micro-nano structured cuprous oxide polycrystalline particles, the specific steps are as follows:

[0066] (1) Under the conditions of mechanical stirring at a speed of 400 rpm, a reaction temperature of 20°C and a reaction pressure of 0.1 MPa, a 6.0 M furfurylamine aqueous solution is slowly added to a uniform and stable copper sulfate aqueous solution with a concentration of 1.0 M at a rate of 2 mL / min, and after the addition is completed, the stirring reaction is continued for 1 h to obtain a mixed solution;

[0067] (2) Under the conditions of mechanical stirring at a speed of 400 rpm, a reaction temperature of 20°C and a reaction pressure of 0.1 MPa, a 1.0 M ascorbic acid aqueous solution is slowly added to the mixed solution obtained in step (1) at a rate of 2.5 mL / min, and after the addition is completed, the stirring reaction is continued for 0.5 h, and the reaction product is collected by centrifugal treatment of the reaction solution;

[0068] Among them, the molar ratio of copper sulfate, furfurylamine and ascorbic acid is 1:1.5:0.75;

[0069] (3) The solid component obtained in step (3) is washed with deionized water and ethanol, vacuum dried in a vacuum oven at 80°C for 6 h, and micro-nano structured cuprous oxide polycrystalline particles are obtained.

[0070] As shown in Figure 3 , the average particle size of the finally prepared micro-nano structured cuprous oxide polycrystalline particles is 1.5 μm, and the micro-nano structured cuprous oxide polycrystalline particles are formed by the co-growth of small-size cuprous oxide crystals with a grain size of 150 nm; the purity of the micro-nano structured cuprous oxide polycrystalline particles is 97.2%; as shown in Figure 8 , the thermal weight loss of the micro-nano structured cuprous oxide polycrystalline particles is 1.25%.

[0071] Comparative Example 1

[0072] A method for preparing micro-nano structure cuprous oxide polycrystalline particles, which is basically the same as Example 2, except that the aqueous furfurylamine solution in step (1) is replaced by an aqueous NaOH solution with an equimolar concentration.

[0073] As shown in Figure 7 , the cuprous oxide prepared in Comparative Example 1 does not have an independent particle structure, but presents as a bulk-grown cuprous oxide mass, with some of the masses reaching a size of tens of microns, and having a clear large-grain growth structure. Since the particle structure cannot be observed and the intercalation and agglomeration between the crystals result in a large overall size, the particle size cannot be counted, proving that the small molecule amine not only provides an alkaline environment in the formation process of the micro-nano structure cuprous oxide polycrystalline particles, but also the specific group connected to the amino group also plays a specific effect in promoting the generation of the independent particle structure of cuprous oxide.

[0074] Example 3

[0075] A method for preparing micro-nano structure cuprous oxide polycrystalline particles, the specific steps being as follows:

[0076] (1) Under the conditions of mechanical stirring at a rate of 300 rpm, a reaction temperature of 20°C and a reaction pressure of 0.1 MPa, an aqueous benzylamine solution with a concentration of 0.24 M was slowly added to an aqueous copper acetate solution which was uniform and stable and had a concentration of 0.1 M, the addition rate being 10 mL / min. After the addition was completed, the stirring reaction was continued for 5 h to obtain a mixed solution;

[0077] (2) Under the conditions of mechanical stirring at a rate of 300 rpm, a reaction temperature of 20°C and a reaction pressure of 0.1 MPa, an aqueous hydrazine hydrate solution with a concentration of 0.07 M was slowly added to the mixed solution obtained in step (1), the addition rate being 7.5 mL / min. After the addition was completed, the stirring reaction was continued for 0.25 h, and the reaction product was collected by centrifugal treatment of the reaction liquid;

[0078] wherein the molar ratio of copper acetate, benzylamine and hydrazine hydrate is 1:0.6:0.525;

[0079] (3) The solid component obtained in step (3) was washed with deionized water and ethanol, and vacuum dried in a vacuum oven at 50°C for 12 h to obtain micro-nano structure cuprous oxide polycrystalline particles.

[0080] As shown in Figure 4 , the average particle size of the micro-nano structure cuprous oxide polycrystalline particles finally prepared is 1.7 μm, and the micro-nano structure cuprous oxide polycrystalline particles are formed by the co-growth of small-size cuprous oxide crystals with a grain size of 240 nm; the purity of the micro-nano structure cuprous oxide polycrystalline particles is 98.1%; asFigure 8 As shown, the thermal weight loss of the micro / nano structured cuprous oxide polycrystalline particles is 1.34%; according to the ISO 18184-2019 standard test, the antiviral rate against HCoV-OC43 virus within 3 minutes is 84.50%.

[0081] like Figure 9 As shown, compared to the commercially available 100 nm-grade cuprous oxide (Cu2O-100) and 1000 nm-grade cuprous oxide (Cu2O-1000), which only achieve antiviral rates of 72.67% and 71.67% respectively, the micro-nano structured cuprous oxide polycrystalline particles synthesized in this invention exhibit significantly superior antiviral effects. In particular, Example 1 achieves an antiviral rate of 99.07%, demonstrating better performance than nanoscale particles, while Example 3 is second best at 84.50%. This may be because the micro-nano structure of the material gives the particles a larger specific surface area, increasing the opportunity for polycrystalline particles to come into contact with viruses under conditions of low aggregation. In addition to specific surface area, according to reference 14 (Nano Lett., 2020, 20: 5367-5375.), the rough structure formed by the crystals stacked on the surface of micro-nano structures makes it easy for viruses to be enriched or tightly embedded with the material. The smaller the grain size on the surface and the closer it is to the size of the virus itself or the virus surface structure, the more obvious this effect may be. This also explains why the antiviral effect of Example 1 is stronger than that of Example 3. According to references such as 15 (Appl. Surf. Sci., 2019, 465: 279-287.), the (111) crystal facet of cuprous oxide generally has higher activity in applications. Among the various forms of cuprous oxide, the octahedral form has the highest (111) crystal facet exposure ratio. The cuprous oxide crystals that make up the polycrystalline particles of micro-nano structured cuprous oxide in this invention have a truncated octahedral shape and also have a high (111) crystal facet exposure ratio. Therefore, compared with common spherical or amorphous crystals, they have higher antiviral activity and can achieve better antiviral effects than conventional nano-sized cuprous oxide.

[0082] like Figure 11 As shown, the eight hexagonal faces of the truncated octahedron correspond to the (111) crystal plane of cuprous oxide, and the six quadrilateral faces correspond to the (100) crystal plane of cuprous oxide. The grain interpretation is based on reference 16 (Prog. Mater Sci., 2018, 96:111-173.). By comparing with the standard grain morphology of cuprous oxide in the literature, it is shown that the small-sized cuprous oxide crystals are truncated octahedral in shape, and the crystal plane structure of cuprous oxide grains is further determined.

[0083] Example 4

[0084] A method for preparing micro / nano-structured polycrystalline cuprous oxide particles, the specific steps of which are as follows:

[0085] (1) under the conditions of mechanical stirring at a rate of 200 rpm, a reaction temperature of 80 °C, and a reaction pressure of 0.1 MPa, a uniform and stable aqueous copper chloride solution with a concentration of 1.2 M was slowly added dropwise with an aqueous phenethylamine solution with a concentration of 9.6 M at a rate of 1 mL / min, and after the dropwise addition was completed, the reaction was continued for 0.5 h with stirring to obtain a mixed solution;

[0086] (2) under the conditions of mechanical stirring at a rate of 200 rpm, a reaction temperature of 80 °C, and a reaction pressure of 0.1 MPa, the mixed solution obtained in step (1) was slowly added dropwise with an aqueous sodium sulfite solution with a concentration of 2.0 M at a rate of 1.25 mL / min, and after the dropwise addition was completed, the reaction was continued for 3 h with stirring, and the reaction product was collected by centrifugal treatment of the reaction liquid;

[0087] wherein the molar ratio of copper chloride, phenethylamine, and sodium sulfite is 1:2:1.25;

[0088] (3) the solid component obtained in step (3) was washed with deionized water and ethanol, and vacuum dried in a vacuum oven at 80 °C for 6 h to obtain micro-nano structured cuprous oxide polycrystalline particles.

[0089] As shown in Figure 5 , the average particle size of the finally prepared micro-nano structured cuprous oxide polycrystalline particles is 2.3 μm, the micro-nano structured cuprous oxide polycrystalline particles are formed by the intergrowth of small size cuprous oxide crystals with a grain size of 400 nm, the purity of the micro-nano structured cuprous oxide polycrystalline particles is 97.6%, and the thermal weight loss of the micro-nano structured cuprous oxide polycrystalline particles is 1.28%.

[0090] Example 5

[0091] A method for preparing micro-nano structured cuprous oxide polycrystalline particles, the specific steps being as follows:

[0092] (1) under the conditions of mechanical stirring at a rate of 300 rpm, a reaction temperature of 20 °C, and a reaction pressure of 0.1 MPa, a uniform and stable aqueous copper acetate solution with a concentration of 0.1 M was slowly added dropwise with an aqueous n-butylamine solution with a concentration of 0.24 M at a rate of 5 mL / min, and after the dropwise addition was completed, the reaction was continued for 5 h with stirring to obtain a mixed solution;

[0093] (2) under the conditions of mechanical stirring at a rate of 300 rpm, a reaction temperature of 20 °C, and a reaction pressure of 0.1 MPa, the mixed solution obtained in step (1) was slowly added dropwise with an aqueous hydrazine hydrate solution with a concentration of 0.07 M at a rate of 7.5 mL / min, and after the dropwise addition was completed, the reaction was continued for 0.25 h with stirring, and the reaction product was collected by centrifugal treatment of the reaction liquid;

[0094] wherein the molar ratio of copper acetate, n-butylamine and hydrazine hydrate is 1:0.6:0.525;

[0095] (3) The solid component obtained in step (3) is washed with deionized water and ethanol, and vacuum dried in a vacuum oven at 50°C for 12 h to obtain micro-nano structure cuprous oxide polycrystalline particles.

[0096] As shown in Figure 6 , the average particle size of the finally prepared micro-nano structure cuprous oxide polycrystalline particles is 1.0 μm, the micro-nano structure cuprous oxide polycrystalline particles are formed by the symbiotic growth of small size cuprous oxide crystals with a grain size of 600 nm; the purity of the micro-nano structure cuprous oxide polycrystalline particles is 98.4%; and the thermal weight loss of the micro-nano structure cuprous oxide polycrystalline particles is 1.02%.

[0097] According to Figure 10 the XRD spectrum, the peaks from example 1 to example 5 are gradually sharp, and the half peak width of the diffraction peak gradually decreases, indicating that the grain size of the micro-nano structure cuprous oxide polycrystalline particles gradually increases. The actual grain size value calculated by substituting the half peak width of the strongest diffraction peak at 36.418° of cuprous oxide into the Scherrer formula is consistent with the trend presented in the SEM picture, proving that the grain size in the cuprous oxide particles is indeed precisely controlled.

Claims

1. A method for controlling the grain size of small-sized cuprous oxide crystals in a micro-nanostructured cuprous oxide polycrystal particle, the method comprising: The micro-nano structure cuprous oxide polycrystal particles are prepared by adding an aqueous solution of an organic amine into an aqueous solution of a divalent copper salt, stirring the reaction, then adding a reducing agent solution into the reaction liquid, continuing to stir the reaction, and then centrifuging and drying the reaction liquid. ​ The average particle size of the micro-nano structure cuprous oxide polycrystal particles is 1-2.3 μm, and the micro-nano structure cuprous oxide polycrystal particles are formed by the co-growth of small-size cuprous oxide crystals. The crystal grain size of the small-size cuprous oxide crystals forming the micro-nano structure cuprous oxide polycrystal particles is controlled by changing the type of the organic amine, and the crystal grain size of the small-size cuprous oxide crystals ranges from 40 nm to 600 nm.

2. The method according to claim 1, wherein the grain size of the small-sized cuprous oxide crystal in the micro-nano structured cuprous oxide polycrystal is controlled. The specific steps for preparing the micro-nano structure cuprous oxide polycrystal particles are as follows: (1) Under mechanical stirring at a speed of 200-500 rpm, an aqueous solution of an organic amine is slowly added into a uniform and stable aqueous solution of a divalent copper salt at a rate of 1-10 mL / min, and the reaction is continued to stir for 0.5-5 h after the addition is completed to obtain a mixed solution; (2) Under mechanical stirring at a speed of 200-500 rpm, an aqueous solution of a reducing agent is slowly added into the mixed solution obtained in step (1) at a rate of 1.25-7.5 mL / min, and the reaction is continued to stir for 0.25-3 h after the addition is completed, and the reaction product is collected by centrifugation; (3) The solid component obtained in step (3) is washed with deionized water and ethanol, and vacuum dried in a vacuum oven at 50-80 °C for 6-12 h to obtain the micro-nano structure cuprous oxide polycrystal particles.

3. The method according to claim 2, wherein the grain size of the small-sized cuprous oxide crystal in the micro-nano structured cuprous oxide polycrystal is controlled. In steps (1) and (2), the reaction temperature is 20-80 °C, and the reaction pressure is 0.1 MPa.

4. The method according to claim 2, wherein the grain size of the small-sized cuprous oxide crystal in the micro-nano structured cuprous oxide polycrystal is controlled. In step (1), the divalent copper salt is one or more of copper acetate, copper sulfate, copper nitrate and copper chloride, the concentration of the aqueous solution of the divalent copper salt is 0.1-1.2 M, and the concentration of the aqueous solution of the organic amine is 0.24-9.6 M.

5. The method according to claim 2, wherein the grain size of the small-sized cuprous oxide crystal in the micro-nano structured cuprous oxide polycrystal is controlled. In step (2), the reducing agent is one of hydrazine hydrate, ascorbic acid, glucose and sodium sulfite, and the concentration of the aqueous solution of the reducing agent is 0.07-2.0 M.

6. The method according to claim 2, wherein the grain size of the small-sized cuprous oxide crystal in the micro-nano structured cuprous oxide polycrystal is controlled. The molar ratio of the divalent copper salt, the organic amine and the reducing agent is 1:0.6-2:0.525-2.

7. The method according to claim 2, wherein the grain size of the small-sized cuprous oxide crystal in the micro-nano structured cuprous oxide polycrystal is controlled. The purity of the micro-nano structure cuprous oxide polycrystal particles is greater than 95%.

8. The method according to claim 7, wherein the size of the small-sized cuprous oxide crystal grains is controlled. The thermal weight loss of the micro-nano structure cuprous oxide polycrystal particles is less than 4%.

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