Preparation Method of Spindle-Shaped Nano-Copper Oxide

Abstract

The present disclosure provides a method for preparing spindle-shaped nano-copper oxide, which relates to the technical field of the preparation of powder nano-materials. The method includes: under the action of magnetic stirring, configuring a copper salt into an aqueous solution of a copper precursor and configuring an alkali into an alkaline mixed solution; using a high-frequency ultrasonic dispersion device to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol and converting the alkaline mixed solution into a micro-nano aerosol containing a mixed alkali; performing gas-phase confined micro-region mixing on the copper-containing micro-nano aerosol and the micro-nano aerosol containing the mixed alkali to obtain a copper-alkali mixed solution, and transferring the copper-alkali mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nano-particle solution containing a copper compound; performing solid-liquid separation, washing, drying, and calcination on the nano-particle solution containing the copper compound to obtain spindle-shaped nano-copper oxide powder. The present disclosure solves the problem that it is impossible to use a mixed alkali as a morphology control agent to synthesize spindle-shaped CuO nanocrystals.

Description

Technical Field

[0001] The present disclosure relates to the technical field of the preparation of metal powder nanomaterials, and more particularly, to a method for preparing spindle-shaped nano-copper oxide. Background Art

[0002] Compared with traditional large-sized copper oxide powder, nano-sized copper oxide powder has higher catalytic activity and selectivity, and shows significant advantages in other properties. For example, nano-copper oxide with a particle size in the range of 1-100 nm exhibits strange physical and chemical properties in terms of magnetism, light absorption, chemical activity, thermal resistance, catalytic performance, and melting point due to its unique surface effect, quantum size effect, volume effect, and macroscopic quantum tunneling effect. These excellent properties make nano-copper oxide one of the widely used and highly concerned inorganic materials.

[0003] However, although there are currently many methods for preparing CuO nanomaterials with different morphologies and sizes, the sizes of the prepared copper oxide powders are relatively large. How to obtain copper oxide powders with finer particle sizes has become an urgent problem to be solved.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] In view of this, a method for preparing spindle-shaped nano-copper oxide is provided, which can at least overcome to a certain extent the problem of inability to obtain copper oxide powders with finer particle sizes due to the limitations and defects of related technologies.

[0006] According to one aspect of the present disclosure, a method for preparing spindle-shaped nano-copper oxide is provided. The method for preparing spindle-shaped nano-copper oxide includes the following steps:

[0007] Step 1, under the action of magnetic stirring, a copper salt is configured into an aqueous solution of a copper precursor, and an alkali is configured into an alkaline mixed solution;

[0008] Step 2, using a high-frequency ultrasonic dispersion device to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol, and convert the alkaline mixed solution into a micro-nano aerosol containing a mixed alkali;

[0009] Step 3, subjecting the copper-containing micro-nano aerosol and the micro-nano aerosol containing the mixed alkali to gas-phase confined micro-region mixing to obtain a copper-alkali mixed solution, and transferring the copper-alkali mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nano-particle solution containing a copper compound;

[0010] Step 4: Perform solid-liquid separation, washing, drying, and calcination on the nanoparticle solution of the copper-containing compound to obtain spindle-shaped nano-copper oxide powder.

[0011] In an exemplary embodiment of the present disclosure, the copper salt includes at least one of copper chloride, copper acetate, copper sulfate, or copper nitrate;

[0012] The concentration of the aqueous solution of the copper precursor is less than or equal to 200 g / L.

[0013] In an exemplary embodiment of the present disclosure, the alkaline mixed solution is formed by mixing a strong base solution and a weak base solution;

[0014] The strong base solution is a sodium hydroxide solution;

[0015] The weak base solution includes at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and ammonia water;

[0016] The concentration of the alkaline mixed solution is less than or equal to 180 g / L;

[0017] The pH value of the alkaline mixed solution ranges between 12 and 14, being in a strongly alkaline state.

[0018] In an exemplary embodiment of the present disclosure, the ultrasonic frequency of the high-frequency ultrasonic dispersion device is less than or equal to 4 MHz.

[0019] In an exemplary embodiment of the present disclosure, the copper-containing micro-nano aerosol is composed of ultra-fine micro-nano droplets with an average size less than or equal to 10 μm;

[0020] The micro-nano aerosol containing the mixed base is composed of ultra-fine micro-nano droplets with an average size less than or equal to 10 μm.

[0021] In an exemplary embodiment of the present disclosure, the gas-phase confined micro-region mixing reaction is carried out at room temperature;

[0022] During the gas-phase confined micro-region mixing reaction, micro-region mixing needs to be carried out within a gas-phase confinement of less than 20 μm.

[0023] In an exemplary embodiment of the present disclosure, during the process of transferring the copper-alkali mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nanoparticle solution of the copper-containing compound, the temperature of the hydrothermal reaction is 100°C to 200°C;

[0024] The reaction duration of the hydrothermal reaction is 1 h to 6 h, and during the hydrothermal reaction, the pressure in the tetrafluoroethylene reaction kettle is 3 MPa to 10 MPa.

[0025] In an exemplary embodiment of the present disclosure, during the solid-liquid separation of the nanoparticle solution of the copper-containing compound, the solid-liquid separation method is centrifugal separation and / or suction filtration separation;

[0026] During the washing of the nanoparticles of the copper-containing compound after solid-liquid separation, the washing solution used is water and / or ethanol;

[0027] During the drying of the washed nanoparticles of the copper-containing compound, the drying method used is thermal drying and / or cold drying;

[0028] During the roasting of the dried nanoparticles of the copper-containing compound, the roasting temperature used is 200 °C to 500 °C, and the atmosphere used during the roasting process is air.

[0029] In an exemplary embodiment of the present disclosure, the size of the single spindle-shaped nano-copper oxide obtained is 100 nm to 1000 nm, and the thickness is 20 nm to 80 nm.

[0030] In an exemplary embodiment of the present disclosure, the method for preparing the spindle-shaped nano-copper oxide further includes: using the prepared spindle-shaped nano-copper oxide to prepare at least one of the following materials: mechanical property materials, optical property materials, and electrical property materials.

[0031] In a method for preparing spindle-shaped nano-copper oxide provided by an exemplary embodiment of the present disclosure, on the one hand, under the action of magnetic stirring, a copper salt is configured into an aqueous solution of a copper precursor, and an alkali is configured into an alkaline mixed solution; then a high-frequency ultrasonic dispersion device is used to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol, and the alkaline mixed solution is converted into a micro-nano aerosol containing a mixed alkali; then the copper-containing micro-nano aerosol and the micro-nano aerosol containing the mixed alkali are subjected to gas-phase confined micro-region mixing to obtain a copper-alkali mixed solution, and the copper-alkali mixed solution is transferred to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nano-particle solution containing a copper compound; finally, the nano-particle solution containing the copper compound is subjected to solid-liquid separation, washing, drying and calcination to obtain spindle-shaped nano-copper oxide powder. Since the preparation of nano-copper oxide powder can be realized based on the copper-containing micro-nano aerosol and the micro-nano aerosol containing the mixed alkali, and the micro-nano aerosol can be transported and dispersed over a long distance through spraying or gas flow, and the size of the micro-nano aerosol is less than 10 μm, it is possible to obtain nano-copper oxide powder with a finer particle size (length: 100 nm to 1000 nm, thickness: 20 nm to 80 nm); on the other hand, due to the high specific surface area of the micro-nano aerosol, it can be evenly distributed in the gas-phase medium, providing more reaction and adsorption sites, thereby improving the mixing reaction efficiency and thus enhancing the preparation efficiency of the nano-copper oxide powder; on the further hand, using a high-frequency ultrasonic dispersion device to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol and convert the alkaline mixed solution into a micro-nano aerosol containing a mixed alkali not only greatly improves the transmission and diffusion rate of the copper source during the mixing process, but also effectively strengthens the transmission and diffusion of the copper salt and the regulation of the copper compound by the micro-nano aerosol of the mixed alkali during the crystal growth process, which is conducive to controlling the morphology and size of the product.

[0032] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present disclosure and, together with the specification, are used to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0034] Figure 1 Schematically showing a flow example diagram of a method for preparing spindle-shaped nano-copper oxide according to an exemplary embodiment of the present disclosure.

[0035] Figure 2Schematically shows a SEM image of spindle-shaped nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Example 1.

[0036] Figure 3 Schematically shows a size distribution diagram of spindle-shaped nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Example 1.

[0037] Figure 4 Schematically shows an XRD (i.e., a spectrum of material structure analysis obtained by X-ray diffraction technology) diagram of spindle-shaped nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Example 1.

[0038] Figure 5 Schematically shows a SEM image of spindle-shaped nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Example 3.

[0039] Figure 6 Schematically shows a size distribution diagram of spindle-shaped nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Example 3.

[0040] Figure 7 Schematically shows a SEM image of spindle-shaped / spherical nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Comparative Example 1.

[0041] Figure 8 Schematically shows a SEM image of coral-like nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Comparative Example 2.

[0042] Figure 9 Schematically shows a size distribution diagram of coral-like nano-copper oxide obtained according to an exemplary embodiment of the present disclosure based on Comparative Example 2.

[0043] Figure 10 Schematically shows a SEM image of copper oxide obtained according to an exemplary embodiment of the present disclosure based on Comparative Example 3. Detailed implementation manners

[0044] Now, example embodiments will be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The same reference numerals in the figures denote the same or similar structures, and thus their detailed descriptions will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0045] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "comprising" and "having" are used to mean an open inclusion and refer to the possibility of the existence of additional elements / components / etc. in addition to the listed elements / components / etc.; the terms "first", "second", "third", etc. are used only as labels and are not a limitation on the quantity of their objects.

[0046] In recent years, the morphology research of nanomaterials has attracted extensive attention in the field of materials science. Research shows that the size and morphology of nanoparticles have an important impact on their properties; in the process of practical applications, the same nanomaterial often exhibits completely different physical and chemical properties due to differences in morphology. And copper oxide (CuO), as an important inorganic material, has the advantages of rich resources, stable chemical properties, non-toxicity, and simple preparation, and it can not only be used as a catalyst and its carrier, but also as an electrode activation material and rocket propellant, thus making copper oxide widely used in the fields of catalysis, superconductivity, ceramics, etc. Further, in the field of catalysis, copper oxide powder, as the main component of the catalyst, exhibits excellent performance in various catalytic reactions such as oxidation, hydrogenation, NO reduction, CO oxidation, and hydrocarbon combustion.

[0047] However, although there are currently many methods to prepare CuO nanomaterials with different morphologies and sizes (i.e., prepare CuO crystals with a particle size of 1 - 100 nm), there is no record of the method of synthesizing spindle-shaped CuO nanocrystals using mixed alkali as a morphology control agent.

[0048] Based on this, the exemplary embodiments of the present disclosure first provide a method for preparing spindle-shaped nano-copper oxide. Specifically, as shown in Figure 1 The method for preparing spindle-shaped nano-copper oxide may include the following steps:

[0049] Step S110. Under the action of magnetic stirring, configure a copper salt into an aqueous solution of a copper precursor, and configure an alkali into an alkaline mixed solution;

[0050] Step S120. Use a high-frequency ultrasonic dispersion device to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol, and convert the alkaline mixed solution into a mixed-alkali-containing micro-nano aerosol;

[0051] Step S130. Perform gas-phase confined micro-region mixing on the copper-containing micro-nano aerosol and the mixed-alkali-containing micro-nano aerosol to obtain a copper-alkali mixed solution, and transfer the copper-alkali mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nano-particle solution containing a copper compound;

[0052] Step S140. Perform solid-liquid separation, washing, drying, and calcination on the nanoparticle solution of the copper-containing compound to obtain spindle-shaped nano-copper oxide powder.

[0053] In the preparation method of the spindle-shaped nano-copper oxide described above, on the one hand, under the action of magnetic stirring, a copper salt is configured into an aqueous solution of a copper precursor, and an alkali is configured into an alkaline mixed solution; then, a high-frequency ultrasonic dispersion device is used to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol, and the alkaline mixed solution is converted into a micro-nano aerosol containing mixed alkali; then, the copper-containing micro-nano aerosol and the micro-nano aerosol containing mixed alkali are subjected to gas-phase confined micro-region mixing to obtain a copper-alkali mixed solution, and the copper-alkali mixed solution is transferred to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nanoparticle solution of a copper-containing compound; finally, solid-liquid separation, washing, drying, and calcination are performed on the nanoparticle solution of the copper-containing compound to obtain spindle-shaped nano-copper oxide powder; since the preparation of nano-copper oxide powder can be realized based on the copper-containing micro-nano aerosol and the micro-nano aerosol containing mixed alkali, and the micro-nano aerosol can be transmitted and dispersed over a long distance through spraying or gas flow, and the size of the micro-nano aerosol is less than 10 μm, it is possible to obtain nano-copper oxide powder with a finer particle size (length: 100 nm to 1000 nm, thickness: 20 nm to 80 nm); on the other hand, due to the high specific surface area of the micro-nano aerosol, it can be evenly distributed in the gas-phase medium, providing more reaction and adsorption sites, thereby improving the mixing reaction efficiency and thus enhancing the preparation efficiency of nano-copper oxide powder; on the further hand, using a high-frequency ultrasonic dispersion device to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol and the alkaline mixed solution into a micro-nano aerosol containing mixed alkali not only greatly improves the transmission and diffusion rate of the copper source during the mixing process, but also effectively strengthens the transmission and diffusion of the copper salt and the regulation of the copper-containing compound by the micro-nano aerosol containing mixed alkali during crystal growth, which is conducive to controlling the morphology and size of the product.

[0054] Hereinafter, the preparation method of the spindle-shaped nano-copper oxide described in the exemplary embodiments of the present disclosure will be further explained and illustrated with reference to the accompanying drawings.

[0055] First, the technical implementation principle of the exemplary embodiments of the present disclosure is explained and described. Specifically, for the preparation method of spindle-shaped nano-copper oxide recorded in the exemplary embodiments of the present disclosure, an aqueous copper salt solution and an alkaline mixed solution are first prepared, which creates favorable conditions for the nano-scale dispersion of copper salts and the regulation of crystal nucleation and growth. Then, the high-frequency ultrasonic dispersion device technology is used to separately transform them into a copper-containing micro-nano aerosol and a mixed-alkali-containing micro-nano aerosol formed by ultra-fine nano-droplets, constructing a confined micro-region mixing environment. Immediately afterwards, the hydrothermal synthesis method is adopted, and the reaction kinetic conditions for crystal growth are optimized by changing the reaction temperature, time, pressure, pH value, etc., to strengthen the transport and crystal growth modes during the reaction between the copper source and the mixed alkali. Thus, nano-particles of copper-containing compounds are obtained through nano-scale reactions, and then through solid-liquid separation, washing, drying, and calcination, spindle-shaped nano-copper oxide is decomposed, realizing the regulation of the morphology and size of nano-copper oxide. It can be seen from this that the exemplary embodiments of the present disclosure use common water-soluble copper precursors as the copper source and ordinary alkaline mixed solutions as the co-control agents for regulating crystal nucleation and growth. By changing factors such as reaction temperature, time, pressure, and pH value, the low nucleation rate and moderate growth rate during crystal growth are regulated, preferentially expanding along one direction, gradually forming a widened middle part and a shrinking end part, and finally realizing the controllable preparation of spindle-shaped nano-copper oxide with high yield. At the same time, the preparation method of spindle-shaped nano-copper oxide recorded in the exemplary embodiments of the present disclosure is simple to operate, the reaction conditions are relatively mild, the production cost is low, it is environmentally friendly, and the prepared spindle-shaped nano-copper oxide is assembled by a large number of nano-sheets. This structure enables the material to perform excellently in terms of mechanical properties, optical properties, electrical properties, etc., and can be widely applied to important fields such as optoelectronic devices and sensors.

[0056] Among them, by changing factors such as reaction temperature, time, pressure, and pH value, the lower nucleation rate and moderate growth rate during crystal growth are regulated, preferentially expanding along one direction, gradually forming a widened middle part and a shrinking end part, and finally achieving the controllable preparation of spindle-shaped nano-copper oxide with high yield, which is manifested in the following aspects: (1) Temperature directly affects the nucleation rate and growth rate of crystals; specifically, based on the specific experimental process, the following conclusions can be drawn: at low temperatures of 100-200 °C, it is beneficial to the slower crystal growth and easy to form regular morphologies, such as spindle-shaped; further, when the temperature is higher than 200 °C, the high temperature promotes rapid growth, which may lead to an increase in particle size or a change in morphology (such as a transition from spindle-shaped to other morphologies); therefore, the reaction is carried out in an environment of 100–200 °C to provide conditions for the formation of spindle-shaped. (2) The reaction time determines the growth stage of the crystal; specifically, based on the specific experimental process, the following conclusions can also be drawn: in a short time (for example, within 1 h), copper oxide mainly nucleates and irregular particles can be generated, and the spindle-shaped structure of the crystal has not yet formed; at a moderate time (for example, within 1-6 h), growth is the main process, which is beneficial to the formation of spindle-shaped structures and the morphology is more regular; further, if the time is too long (for example, after more than 6 h), it will lead to crystal dissolution and regrowth or the formation of aggregates, destroying the spindle-shaped structure; therefore, the reaction is carried out for 1-6 h; (3) In a closed reaction kettle, by indirectly increasing the pressure to between 3 and 10 MPa by increasing the temperature, it is beneficial to the stable growth of spindle-shaped nanostructures, while a greater pressure may cause crystal aggregation or abnormal structure morphology; (4) The pH value affects the hydrolysis degree of copper ions in the solution and determines the nucleation and growth path of the crystal; moreover, in a weakly alkaline environment (that is, when the pH value is relatively low), the crystal growth rate will be inhibited to generate smaller crystals or other morphologies; however, in a strongly alkaline environment, a higher hydroxide ion concentration can promote the selective growth of the crystal (such as the preferential growth along a specific crystal plane), providing balanced nucleation and growth conditions, which is beneficial to the formation of spindle-shaped structures.

[0057] It should also be noted here that in the exemplary embodiments of the present disclosure, it is necessary to use a high-frequency ultrasonic dispersion device to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol, and convert the alkaline mixed solution into a micro-nano aerosol containing mixed alkalis, because micro-nano aerosols have many advantages over ordinary solutions, which can be specifically reflected in: micro-nano aerosols can be transported and dispersed over long distances through spraying or gas flow, and the size of micro-nano aerosols is less than 10 μm, with a relatively high specific surface area. Therefore, they can be evenly distributed in the gas-phase medium, providing more reaction and adsorption sites, improving the efficiency of the mixing reaction, being more sensitive to changes in the external environment (such as temperature, humidity, pressure, etc.), being able to respond quickly, and effectively avoiding phase separation or non-uniformity that may occur in ordinary solutions. Furthermore, the morphology of the prepared material can be controlled, and the size is in the sub-micron level.

[0058] Secondly, a further explanation and description will be given to Figure 1 the preparation method of the spindle-shaped nano-copper oxide shown in

[0059] In step S110, under the action of magnetic stirring, a copper salt is configured into an aqueous solution of a copper precursor, and an alkali is configured into an alkaline mixed solution.

[0060] Specifically, the copper salts recorded here may include but are not limited to copper chloride, copper acetate, copper sulfate, copper nitrate, etc.; at the same time, the concentration of the obtained aqueous solution of the copper precursor needs to be less than or equal to 200 g / L; further, the alkaline mixed solution recorded here can be formed by mixing a strong alkali solution and a weak alkali solution; the strong alkali solution recorded here is a sodium hydroxide solution; the weak alkali solutions recorded here may include but are not limited to sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and ammonia water, etc.; at the same time, the concentration of this alkaline mixed solution needs to be less than or equal to 180 g / L, and the pH value of the alkaline mixed solution needs to be between 12 and 14 to ensure that the alkaline mixed solution is in a strongly alkaline state.

[0061] It should be noted here that since the hydroxide ions in the alkaline mixed solution will undergo a coordination reaction with metal copper ions, thereby changing the nucleation rate and growth direction of copper oxide, causing the material to grow from the core region, growing faster on specific crystal planes and slower on other crystal planes, making the material form a morphology with a wider middle and thinner ends; at the same time, the concentration of the copper salt aqueous solution and the types and concentrations of the selected alkalis meet the requirements for the nucleation growth and morphology size control of the product nano-copper oxide.

[0062] In step S120, a high-frequency ultrasonic dispersion device is used to convert the aqueous solution of the copper precursor into a copper-containing micro-nano aerosol, and convert the alkaline mixed solution into a micro-nano aerosol containing mixed alkalis.

[0063] Specifically, the ultrasonic frequency of the high-frequency ultrasonic dispersion device described herein needs to be less than or equal to 4 MHz; moreover, the copper-containing micro-nano aerosol is composed of ultra-fine micro-nano droplets with an average size less than or equal to 10 μm; the mixed-alkali-containing micro-nano aerosol is also composed of ultra-fine micro-nano droplets with an average size less than or equal to 10 μm. It should be supplemented here that the reason for converting the copper precursor aqueous solution into a copper-containing micro-nano aerosol and the alkaline mixed solution into a mixed-alkali-containing micro-nano aerosol through a high-frequency ultrasonic dispersion device is that the high-frequency ultrasonic dispersion device is conducive to converting the copper salt aqueous solution and the mixed-alkali aqueous solution into aerosol forms that are easier to diffuse, have a smaller average particle size, and a higher specific surface area, effectively strengthening the transport and reaction kinetic conditions during the reaction between the copper source and the mixed alkali. At the same time, a large number of micro-nano reaction regions are constructed, thereby inhibiting the agglomeration and ripening processes of the nanoparticles of the copper-containing compound, and contributing to the realization of the control of the product morphology and size.

[0064] In step S130, the copper-containing micro-nano aerosol and the mixed-alkali-containing micro-nano aerosol are subjected to gas-phase confined micro-region mixing to obtain a copper-alkali mixed solution, and the copper-alkali mixed solution is transferred to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nanoparticle solution of the copper-containing compound.

[0065] Specifically, the gas-phase confined micro-region mixing reaction described herein is carried out at room temperature; meanwhile, during the gas-phase confined micro-region mixing reaction, micro-region mixing needs to be carried out within a gas-phase confinement less than 20 μm; meanwhile, during the preparation of the copper-alkali mixed solution, the copper-containing micro-nano aerosol can also be replaced with a copper-containing aqueous solution with the same components; of course, the mixed-alkali-containing micro-nano aerosol can also be replaced with a mixed-alkali aqueous solution with the same components. In the actual application process, it can be selected according to actual needs, and this example does not make special limitations on this; further, during the process of transferring the copper-alkali mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction to obtain a nanoparticle solution of the copper-containing compound, the temperature of the hydrothermal reaction is 100 °C to 200 °C; moreover, the reaction duration of the hydrothermal reaction is 1 h to 6 h, and during the hydrothermal reaction, the pressure in the tetrafluoroethylene reaction kettle is 3 MPa to 10 MPa. It should be supplemented here that since the reaction temperature has a significant impact on the growth rate and morphology of crystals, a higher temperature usually increases the diffusion rate of solutes and promotes the growth of materials; therefore, when synthesizing a spindle-shaped structure, a moderate temperature can ensure a uniform growth rate, making the middle gradually wider and the two ends gradually narrower; and during the specific hydrothermal reaction process, the spindle-shaped structure can be achieved within the actual reaction condition range, and there are no special restrictions on the specific values.

[0066] It should be further noted here that since the prepared copper-containing solution can include copper-containing micro-nano aerosol and copper-containing aqueous solution; the prepared mixed-alkali-containing solution can include mixed-alkali-containing micro-nano aerosol and mixed-alkali aqueous solution; therefore, in the process of generating the copper-alkali mixed solution, it can be achieved based on the following methods: One implementation method is mixed-alkali-containing micro-nano aerosol + copper-containing micro-nano aerosol; another implementation method is: mixed-alkali-containing micro-nano aerosol + copper-containing aqueous solution; still another implementation method is: mixed-alkali aqueous solution + copper-containing micro-nano aerosol; and yet another implementation method is: mixed-alkali aqueous solution + copper-containing aqueous solution. In the actual application process, the required implementation method can be determined according to actual needs, and this example does not make special restrictions on this.

[0067] In step S140, the nanoparticle solution of the copper-containing compound is subjected to solid-liquid separation, washing, drying, and calcination to obtain spindle-shaped nano-copper oxide powder.

[0068] Specifically, in the process of solid-liquid separation of the nanoparticle solution of the copper-containing compound, the solid-liquid separation method is centrifugal separation and / or suction filtration separation; in the process of washing the nanoparticle of the copper-containing compound after solid-liquid separation, the washing solution used is water and / or ethanol; in the process of drying the nanoparticle of the copper-containing compound after washing, the drying method used is heat drying and / or cold drying; in the process of calcining the nanoparticle of the copper-containing compound after drying, the calcination temperature used is 200 °C to 500 °C, and the atmosphere used in the calcination process is air. At the same time, in the spindle-shaped nano-copper oxide powder prepared based on the above method, the size of a single spindle-shaped nano-copper oxide is 100 nm to 1000 nm, and the thickness is 20 nm to 80 nm.

[0069] So far, the preparation method of spindle-shaped nano-copper oxide recorded in the exemplary embodiments of the present disclosure has been fully realized. Based on the foregoing content, on the one hand, a common water-soluble copper precursor is used as the copper source, and a common alkaline solution is used as the control agent for regulating crystal nucleation and growth. By converting the copper source and the mixed alkali into a micro-nano aerosol form for reaction, a three-dimensional space-confined micro-region reaction condition is constructed, and the mass transfer and reaction kinetic conditions are controlled, realizing the controllable preparation of the morphology of spindle-shaped nano-copper oxide; on the other hand, by subjecting the water-soluble copper source aqueous solution and the mixed alkali aqueous solution to high-frequency ultrasonic dispersion to obtain a micro-nano aerosol, not only is the mass transfer and diffusion rate of the copper source during the mixing process greatly improved, but also the specific surface area of the droplets in the aerosol is greatly increased, effectively strengthening the mass transfer and diffusion of the copper salt and the regulation of the mixed alkali aqueous solution on the copper compound during the crystal growth process, which is beneficial to realizing the control of the product morphology and size; on the further hand, the transport of the micro-nano aerosol is beneficial to improving the dispersibility of the product; then, the hydrothermal synthesis method is used for the reaction, and by changing the reaction temperature, pressure, time, pH, etc. to optimize the reaction kinetic conditions for crystal growth, the copper compound grows, realizing the precise control of the morphology and size of the copper compound nanoparticles in the product. The morphology, size, uniformity, and dispersibility of the prepared nano-copper oxide are significantly better than those of the traditional preparation methods; further, by controlling the solid-liquid separation method, washing method, drying conditions, and calcination route of the copper compound nanoparticles, the precise control of the crystal structure, morphology, and size of the nano-copper oxide is realized, which helps to obtain spindle-shaped nano-copper oxide.

[0070] Hereinafter, specific examples will be used to further explain and illustrate the preparation method of spindle-shaped nano-copper oxide recorded in the exemplary embodiments of the present disclosure. Specifically:

[0071] Example 1

[0072] The preparation method of spindle-shaped nano-copper oxide recorded in the exemplary embodiments of the present disclosure may include the following steps:

[0073] Step 1, respectively prepare a copper salt aqueous solution and an alkaline mixed aqueous solution with copper sulfate, sodium carbonate, and sodium hydroxide; the concentration of the copper salt aqueous solution is 200 g / L, the concentration of the alkaline mixed aqueous solution is 180 g / L, and the pH value in the mixed alkaline solution is 12, in a strongly alkaline state;

[0074] Step 2, use a high-frequency ultrasonic dispersion device with a frequency of 4 MHz to respectively convert the copper salt aqueous solution and the alkaline mixed aqueous solution prepared in Step 1 into a copper-containing micro-nano aerosol and a mixed-alkali-containing micro-nano aerosol; both the copper-containing micro-nano aerosol and the mixed-alkali-containing micro-nano aerosol are formed by ultra-fine micro-nano droplets with an average particle size of less than 10 μm;

[0075] Step 3: Carry out a gas-phase confined micro-region mixing pre-reaction on the mixed alkali micro-nano aerosol and copper-containing micro-nano aerosol obtained in Step 2. Subsequently, quickly transfer the mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction. The reaction temperature is 130 °C, the reaction time is 2 h, the pressure in the reaction kettle is 3 MPa. After cooling to room temperature, collect the nano-particle solution containing copper compounds;

[0076] Step 4: Centrifuge the nano-particle solution containing copper compounds collected in Step 3, wash it with 18.2 MΩ ultrapure water, and dry it at 70 °C in an oven. Then, calcine it in an air atmosphere at 300 °C to obtain spindle-shaped nano-copper oxide powder. Among them, the size of the obtained spindle-shaped nano-copper oxide is about 400 nm, and the thickness of a single lamella is about 50 nm. Among them, the SEM image of the spindle-shaped nano-copper oxide obtained by this method can be referred to Figure 2 as shown, and the size distribution diagram of the spindle-shaped nano-copper oxide obtained by this method can be referred to Figure 3 as shown, and the XRD pattern of the spindle-shaped nano-copper oxide obtained by this method can be referred to Figure 4 as shown.

[0077] Meanwhile, the alkaline aqueous solution in Step 1 of this embodiment can also be replaced with sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate or ammonia water.

[0078] Example 2

[0079] The preparation method of the spindle-shaped nano-copper oxide recorded in the exemplary embodiments of the present disclosure may include the following steps:

[0080] Step 1: Prepare a copper salt aqueous solution and an alkaline mixed aqueous solution from copper sulfate, sodium carbonate and sodium hydroxide respectively. The concentration of the copper salt aqueous solution is 200 g / L, the concentration of the alkaline mixed aqueous solution is 180 g / L, and the pH value of the mixed alkaline solution is 13, being in a strong alkaline state;

[0081] Step 2: Use a high-frequency ultrasonic dispersion device with a frequency of 4 MHz to convert the copper salt aqueous solution and the alkaline mixed aqueous solution prepared in Step 1 into a copper-containing micro-nano aerosol and a mixed alkali micro-nano aerosol respectively. Both the copper-containing micro-nano aerosol and the mixed alkali micro-nano aerosol are formed by ultra-fine micro-nano droplets with an average particle size less than 10 μm;

[0082] Step 3: Carry out a gas-phase confined micro-region mixing pre-reaction on the mixed alkali micro-nano aerosol and copper-containing micro-nano aerosol obtained in Step 2. Subsequently, quickly transfer the mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction. The reaction temperature is 130 °C, the reaction time is 1 h, the pressure in the reaction kettle is 3 MPa. After cooling to room temperature, collect the nano-particle solution containing copper compounds;

[0083] Step 4: Centrifuge the copper compound nanoparticle solution collected in Step 3, wash it with 18.2 MΩ ultrapure water, and freeze-dry it. Then, calcine it in an air atmosphere at 350 °C to obtain spindle-shaped nano-copper oxide powder. Among them, the size of the obtained spindle-shaped nano-copper oxide is about 200 nm, and the thickness of a single lamella is about 30 nm. It should be noted here that based on the SEM image, size distribution diagram, and XRD pattern of the spindle-shaped nano-copper oxide obtained by this method, they are basically similar to those of the spindle-shaped nano-copper oxide obtained in Example 1, so no further elaboration will be provided here.

[0084] Meanwhile, the alkaline aqueous solution in Step 1 of this example can also be replaced by sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, or ammonia water.

[0085] Example 3

[0086] The preparation method of the spindle-shaped nano-copper oxide described in the exemplary embodiments of the present disclosure may include the following steps:

[0087] Step 1: Prepare copper salt aqueous solution and alkaline mixed aqueous solution by dissolving copper sulfate, sodium carbonate, and sodium hydroxide respectively. The concentration of the copper salt aqueous solution is 200 g / L, the concentration of the alkaline mixed aqueous solution is 180 g / L, and the pH value of the mixed alkaline solution is 14, which is in a strongly alkaline state.

[0088] Step 2: Use a high-frequency ultrasonic dispersion device with a frequency of 4 MHz to convert the copper salt aqueous solution and alkaline mixed aqueous solution prepared in Step 1 into copper-containing micro-nano aerosol and mixed-alkali-containing micro-nano aerosol respectively. Both the copper-containing micro-nano aerosol and the mixed-alkali-containing micro-nano aerosol are formed by ultrafine micro-nano droplets with an average particle size less than 10 μm.

[0089] Step 3: Carry out gas-phase confined micro-region mixing pre-reaction on the mixed-alkali-containing micro-nano aerosol and copper-containing micro-nano aerosol obtained in Step 2. Subsequently, quickly transfer the mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction. The reaction temperature is 130 °C, the reaction time is 5 h, the pressure in the reaction kettle is 3 MPa. After cooling to room temperature, collect the nano-particle solution containing copper compounds.

[0090] Step 4: Centrifuge the copper compound nanoparticle solution collected in Step 3, wash it with 18.2 MΩ ultrapure water, dry it in an oven at 70 °C, and then calcine it in an air atmosphere at 400 °C to obtain spindle-shaped nano-copper oxide powder; among them, the size of the obtained spindle-shaped nano-copper oxide is about 620 nm, and the thickness of a single lamella is about 60 nm. Among them, the SEM image of the spindle-shaped nano-copper oxide obtained by this method can be referred to Figure 5 as shown, and the size distribution diagram of the spindle-shaped nano-copper oxide obtained by this method can be referred to Figure 6 as shown.

[0091] Meanwhile, the alkaline aqueous solution in Step 1 of this embodiment can also be replaced with sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate or ammonia water.

[0092] Comparative Example 1

[0093] The preparation method of copper oxide described in this embodiment includes the following steps:

[0094] Step 1: Prepare a copper salt aqueous solution and an alkaline mixed aqueous solution from copper acetate, sodium carbonate and sodium hydroxide respectively; the concentration of the copper salt aqueous solution is 200 g / L, the concentration of the alkaline mixed aqueous solution is 180 g / L, and the pH value of the mixed alkaline solution is 14, in a strongly alkaline state;

[0095] Step 2: Use a high-frequency ultrasonic dispersion device with a frequency of 4 MHz to convert the copper salt aqueous solution and the alkaline mixed aqueous solution prepared in Step 1 into a copper-containing micro-nano aerosol and a mixed-alkali-containing micro-nano aerosol respectively; both the copper-containing micro-nano aerosol and the mixed-alkali-containing micro-nano aerosol are formed by ultrafine micro-nano droplets with an average particle size of less than 10 μm;

[0096] Step 3: Carry out gas-phase confined micro-region mixing pre-reaction on the mixed-alkali-containing micro-nano aerosol and the copper-containing micro-nano aerosol obtained in Step 2, and then quickly transfer the mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction. The reaction temperature is 130 °C, the reaction time is 2 h, the pressure in the reaction kettle is 3 MPa, and after cooling to room temperature, collect the copper compound nanoparticle solution;

[0097] Step 4: Centrifuge the copper compound nanoparticle solution collected in Step 3, wash it with 18.2 MΩ ultrapure water, dry it in an oven at 70 °C, and then calcine it in an air atmosphere at 300 °C to obtain spindle-shaped nano-copper oxide powder, but spherical particles are generated; among them, the size of the obtained spindle-shaped nano-copper oxide is about 400 nm, the thickness of a single lamella is about 50 nm, and the size of the spherical particles is about 20-30 nm; further, the SEM image of the spindle-shaped / spherical nano-copper oxide obtained by this method can be referred toFigure 7 as shown; based on Figure 7 it can be known that by using copper acetate as the copper salt, although spindle-shaped nano copper oxide can be obtained, the obtained nano copper oxide is impure.

[0098] Meanwhile, the copper salt aqueous solution described in the first step of this comparative example can also be replaced with copper nitrate or copper chloride; the alkaline aqueous solution can also be replaced with sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate or ammonia water.

[0099] Comparative Example 2

[0100] The preparation method of copper oxide described in this example includes the following steps:

[0101] Step 1, prepare copper sulfate, sodium carbonate and sodium hydroxide into a copper salt aqueous solution and an alkaline mixed aqueous solution respectively; the concentration of the copper salt aqueous solution is 200 g / L, the concentration of the alkaline mixed aqueous solution is 180 g / L, and the pH value in the mixed alkaline solution is between 12 and 14, in a strong alkaline state;

[0102] Step 2, use a high-frequency ultrasonic dispersion device with a frequency of 4 MHz to convert the copper salt aqueous solution and the alkaline mixed aqueous solution prepared in Step 1 into a copper-containing micro-nano aerosol and a mixed-alkali-containing micro-nano aerosol respectively; both the copper-containing micro-nano aerosol and the mixed-alkali-containing micro-nano aerosol are formed by ultra-fine micro-nano droplets with an average particle size of less than 10 μm;

[0103] Step 3, add the mixed-alkali-containing micro-nano aerosol obtained in Step 2 into the copper-containing micro-nano aerosol for gas-phase confined micro-region mixing pre-reaction, and then quickly transfer the mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction. The reaction temperature is 120 °C, the reaction time is 2 h, and after cooling to room temperature, collect the nano-particle solution containing copper compounds;

[0104] Step 4, centrifuge the nano-particle solution containing copper compounds collected in Step 3, wash it with 18.2 MΩ ultrapure water, dry it in an oven at 70 °C, and then calcine it in an air atmosphere at 300 °C to 400 °C to obtain coral-like nano copper oxide powder; finally, reduce it in a hydrogen atmosphere at 150 °C to 200 °C to obtain coral-like nano copper powder. The size of the coral-like nano copper oxide is about 183 nm, and the thickness of a single lamella is about 30 nm. Among them, the SEM image of the coral-like nano copper oxide obtained based on this method can be referred to Figure 8 as shown, the size distribution diagram of the coral-like nano copper oxide obtained based on this method can be referred to Figure 9 as shown; based on Figure 8 it can be known that if the temperature of the hydrothermal reaction is reduced, spindle-shaped nano copper oxide cannot be obtained.

[0105] Meanwhile, the copper salt aqueous solution in the first step of this comparative example can also be replaced with copper acetate, copper nitrate or copper chloride; the alkaline aqueous solution can also be replaced with sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate or ammonia water.

[0106] Comparative Example 3:

[0107] Step 1, under magnetic stirring, prepare a copper salt aqueous solution and an alkaline mixed aqueous solution from copper sulfate, sodium carbonate and sodium hydroxide respectively; the concentration of the copper salt aqueous solution is 200 g / L, the concentration of the alkaline mixed aqueous solution is 180 g / L, and the pH value in the mixed alkaline solution is between 12 and 14, in a strong alkaline state;

[0108] Step 2, mix and pre-react the copper salt aqueous solution and the alkaline mixed aqueous solution obtained in Step 1, and then quickly transfer the mixed solution to a polytetrafluoroethylene reaction kettle for hydrothermal reaction. The reaction temperature is 130 °C, the reaction time is 6 h, the pressure in the reaction kettle is 3 MPa. After cooling to room temperature, collect the nanoparticle solution containing copper compounds;

[0109] Step 3, centrifuge the nanoparticle solution containing copper compounds collected in Step 2, wash it with 18.2 MΩ ultrapure water, dry it in an oven at 70 °C, and then calcine it in an air atmosphere at 400 °C to obtain spindle-shaped copper oxide powder; among them, the size of the obtained spindle-shaped copper oxide is about 1-3 μm, and the thickness of a single lamella is about 200 nm. Among them, the SEM image of the spindle-shaped copper oxide obtained based on this method can be referred to Figure 10 as shown; further, from Figure 10 it can be known that the morphology of the copper oxide obtained based on this comparative example is not uniform, including not only spindle-shaped ones, but also spherical and fusiform ones, and the particle size is relatively large.

[0110] Meanwhile, the copper salt aqueous solution in the first step of this example can also be replaced with copper acetate, copper nitrate or copper chloride; the alkaline aqueous solution can also be replaced with sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate or ammonia water. Further, from Comparative Example 3, it can be known that in the non-micro-nano aerosol state, if spindle-shaped copper oxide needs to be obtained, the required reaction time is significantly increased and the size of the obtained spindle-shaped copper oxide is also relatively large.

[0111] It should be further supplemented and explained here that in the hydrothermal reaction, Examples 1-3 and Comparative Examples 1-3 all adopted a reaction temperature of 130 °C and a pressure of 3 Mpa; however, in the actual application process, other temperatures within the range can also be adopted. The higher the reaction temperature, the greater the pressure value, and it can be selected according to actual needs. This disclosure does not make special restrictions on this.

[0112] In addition, the above-mentioned drawings are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present disclosure, rather than for limiting purposes. It is easy to understand that the processes shown in the above-mentioned drawings do not indicate or limit the chronological order of these processes. Additionally, it is also easy to understand that these processes can be executed, for example, synchronously or asynchronously in multiple modules.

[0113] Those skilled in the art will readily conceive of other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include well-known knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

[0114] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present disclosure are pointed out by the appended claims.

Claims

1. A method for preparing spindle-shaped nano copper oxide, characterized in that: The preparation method of the spindle-shaped nano copper oxide comprises the following steps: Step 1: Under the action of magnetic stirring, the copper salt is configured as a copper precursor aqueous solution, and the base is configured as an alkaline mixed solution; wherein the copper salt includes at least one of copper chloride, copper acetate, copper sulfate or copper nitrate, and the pH value of the alkaline mixed solution is between 12 and 14, which is in a strong alkaline state; Step 2: using a high-frequency ultrasonic dispersion device to convert the copper precursor aqueous solution into a micro-nano aerosol containing copper, and convert the alkaline mixed solution into a micro-nano aerosol containing a mixed alkali; wherein the ultrasonic frequency of the high-frequency ultrasonic dispersion device is less than or equal to 4 MHz; Step 3, mixing the copper-containing micro-nano aerosol and the mixed alkali-containing micro-nano aerosol in a gas phase confined micro-region to obtain a copper-alkali mixed solution, and transferring the copper-alkali mixed solution to a polytetrafluoroethylene reactor for hydrothermal reaction to obtain a nanoparticle solution containing copper compounds; wherein the temperature of the hydrothermal reaction is 100°C to 200°C; the reaction time of the hydrothermal reaction is 1 h to 6 h, and during the hydrothermal reaction, the pressure in the polytetrafluoroethylene reactor is 3 MPa to 10 MPa; Step 4: solid-liquid separation, washing, drying and calcining the nanoparticle solution containing the copper compound to obtain spindle-shaped nano copper oxide powder; wherein the size of the obtained single spindle-shaped nano copper oxide is 100 nm ~ 1000 nm, and the thickness is 20 nm ~ 80 nm.

2. The method for preparing spindle-shaped nano copper oxide according to claim 1, characterized in that: The concentration of the copper precursor aqueous solution is less than or equal to 200 g / L.

3. The method for preparing spindle-shaped nano copper oxide according to claim 1, characterized in that: The alkaline mixed solution is formed by mixing a strong alkaline solution and a weak alkaline solution; The strong alkaline solution is a sodium hydroxide solution; The weak alkaline solution includes at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate and ammonia water; The concentration of the alkaline mixed solution is less than or equal to 180 g / L.

4. The method for preparing spindle-shaped nano copper oxide according to claim 1, characterized in that: The copper-containing micro-nano aerosol is composed of ultra-fine nano-droplets with an average size of less than or equal to 10 μm; The micro-nano aerosol containing mixed alkali is composed of ultra-fine nano-droplets with an average size of less than or equal to 10 μm.

5. The method for preparing spindle-shaped nano copper oxide according to claim 1, characterized in that: The gas phase confined micro-region mixing reaction is carried out at room temperature; In the process of gas phase confined micro-region mixing reaction, micro-region mixing needs to be carried out in the gas phase confinement less than 20 μm.

6. The method for preparing spindle-shaped nano copper oxide according to claim 1, characterized in that: In the process of solid-liquid separation of the nanoparticle solution containing the copper compound, the solid-liquid separation is carried out by centrifugal separation or suction filtration separation; In the process of washing the nanoparticles containing the copper compound after solid-liquid separation, the washing solution used is water and / or ethanol; In the process of drying the washed copper compound-containing nanoparticles, the drying method used is heat drying or cold drying; In the process of calcining the dried copper compound-containing nanoparticles, the calcination temperature used is 200° C. to 500° C., and the atmosphere used in the calcination process is air.

7. The method for preparing spindle-shaped nano copper oxide according to any one of claims 1 to 6, characterized in that: The method for preparing the spindle-shaped nano copper oxide also includes: The prepared spindle-shaped nano copper oxide is used to prepare at least one of the following materials: Mechanical properties materials, optical properties materials and electrical properties materials.

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