Preparation method of Cu nano-flowers and its application in detecting the sugar content of cola

Abstract

The present invention discloses a preparation method of Cu nanoflowers and their application in the detection of cola sugar content. The preparation process of Cu elemental nanoflowers includes dispersing the prefabricated powder in a copper sulfate solution, stirring evenly, adding a sodium borohydride solution with a specified concentration, and reacting at room temperature for 2-3 hours. In addition, the present invention also discloses a method for detecting cola sugar content by modifying a working electrode with Cu elemental nanoflowers. Its chronoamperometric response signal decreases linearly as the cola concentration is diluted. The concentration of sugar in cola can be calculated from the obtained linear fitting equation. The detection method provided by the present invention has low cost and high selectivity, and has high commercial value.

Description

Technical Field

[0001] The invention relates to the technical field of nano material preparation and application, and in particular to a method for preparing Cu nano flowers and application thereof in cola sugar content detection. Background Art

[0002] In recent years, with the advancement of science and technology and the improvement of human living standards, unhealthy eating has emerged one after another, causing a series of diseases, among which diabetes is one of the most common and incurable diseases. Therefore, it is extremely important to detect sugars in food in a timely and rapid manner.

[0003] As a classic drink, Coca-Cola has been widely loved by young people for more than a century. However, its high sugar content causes people to consume too much sugar (such as caramel, glucose, etc.). At present, many fake sugar-free colas are quietly emerging on the market. However, it is impossible to distinguish the content of sugar in cola simply by taste. Therefore, accurate quality inspection of the content of sugar in cola is of great significance to protecting people's healthy lives.

[0004] Electrochemical sensing is based on the change of electrical signals generated by the interfacial catalytic oxidation process. The sensitivity and selectivity of its detection mainly depend on the electrode material. Commonly used electrode materials are precious metal materials such as Pt, Pd and carbon-based composite materials. However, most precious metal materials are expensive, while carbon-based composite materials have poor selectivity. Therefore, being able to provide a cheap and highly selective electrode material has become an important prerequisite for beverage detection.

[0005] Metallic Cu is one of the earliest metals used by humans, with good ductility and conductivity. Nano-Cu is considered one of the most promising electrode materials for enzyme-free glucose electrochemical sensors due to its good stability and biocompatibility. However, there are few studies on the use of Cu as a biosensor material. This is because the actual preparation of Cu nanocrystals still has the following problems:

[0006] 1. In order to ensure the purity of the product, the preparation of nano-scale Cu element often requires the use of a strong reducing agent. Strong reducing agents such as hydrazine hydrate cause great environmental pollution and are not conducive to large-scale production.

[0007] 2. The traditional liquid phase method for preparing Cu single crystal nuclei easily grows into nanoparticles, and the nanoparticles easily agglomerate, resulting in a relatively low actual specific surface area. When used as an electrode material, the sensitivity is significantly reduced.

[0008] Although the addition of small organic molecule surfactants can assist the growth of Cu nanocrystals and obtain anisotropic structures, since the organic surfactant molecules adsorbed on the Cu surface are difficult to remove by traditional cleaning methods, the coverage of active sites will also lead to a decrease in sensitivity. Summary of the invention

[0009] The technical problem to be solved by the present invention is the technical problem of preparing Cu elemental nanomaterials mentioned in the background art, and using Cu elemental nanoflowers to modify the working electrode to achieve quantitative detection of sugar in cola. In the preparation of Cu elemental nanocrystals, the present invention adopts relatively mild preparation conditions, uses the disproportionation reaction of Cu2O to prepare Cu elemental nanocrystals, and controls the rate of the disproportionation reaction by controlling the concentrations of sodium borohydride solution and copper sulfate solution, and successfully prepares Cu elemental nanocrystals with a flower-like structure formed by the stacking of anisotropic nanosheets. The nanoflower-like structure is conducive to providing a fast ion transfer channel, exposing more active sites, and increasing the contact area between the active substance and the electrolyte. When used as an electrode material, Cu nanoflowers have high selectivity. There are obvious differential response currents for sugary colas with different concentrations, and the current density has a linear function relationship with the sugar concentration in cola. For sugar-free colas with different concentrations, the response current hardly changes, showing good selectivity.

[0010] A preparation method of Cu nanoflowers is provided, and the specific operation steps are as follows:

[0011] (1) Prepare a copper sulfate solution with a concentration of 8.9 mg / mL, sequentially add sodium citrate, sodium carbonate, and potassium bromide powders in proportion, stir evenly, place it in a water bath at 70 °C, add a glucose solution with a concentration of 297 mg / mL, take it out after reacting for 4 - 5 minutes to obtain an orange precipitate, and filter it with filter paper;

[0012] (2) Dissolve the filtered orange powder in an aqueous copper sulfate solution with a concentration of 50 mg / mL, and obtain mixture 1 after ultrasonic dispersion;

[0013] (3) Add a NaBH4 ethanol solution with a volume concentration of 10 mg / mL to mixture 1 to obtain mixture 2;

[0014] (4) Stir mixture 2 and react at room temperature for 2 hours to obtain a gray precipitate. After centrifugal separation, wash it once with deionized water and ethanol, and then perform centrifugal separation again and dry it in a blast dryer. The obtained product is Cu nanoflowers.

[0015] The whole preparation process is based on the disproportionation reaction of the intermediate product Cu2O to precipitate Cu elemental, and controls the disproportionation reaction rate by regulating the concentrations of copper sulfate solution and NaBH4 ethanol solution to assist the growth of Cu elemental nanocrystals into a nanoflower structure.

[0016] Correspondingly, the present invention also discloses a Cu elemental nanoflower obtained by the above preparation method of Cu nanoflowers.

[0017] In addition, the present invention also discloses a method for detecting sugar in cola using Cu nanoflowers, and the specific detection method is as follows:

[0018] (1) Stir the cola at room temperature for 2 hours until its carbonic acid is completely decomposed, then add KOH powder to adjust the pH of the solution to 14.0;

[0019] (2) Use deionized water to prepare a suspension of Cu nanoflower powder. Take a certain mass of the suspension and drop it onto the working electrode. After the liquid evaporates, then drop a perfluorosulfonic acid-based polymer solution with a concentration of 0.05% to form a proton exchange membrane. The modified electrode is the working electrode. Use Ag / AgCl as the reference electrode and a Pt wire electrode as the counter electrode, connect the electrochemical workstation, and measure the chronoamperometric response curve;

[0020] (3) Add KOH with a concentration of 1 mol / L to dilute the cola concentration, set the working potential (1.1 V vs Ag / AgCl), and continuously measure the chronoamperometric response curves at different concentrations;

[0021] (4) According to the functional relationship between the response current density and the cola concentration, fit a linear equation;

[0022] (5) Measure the response current of any cola concentration to be measured, and use the linear fitting equation to calculate the sugar content in the cola solution.

[0023] Implementing the present invention has the following beneficial effects:

[0024] 1. The present invention provides a method for Cu elemental nanoflowers, with a simple preparation process, no toxic substances involved in the formula, and being environmentally friendly.

[0025] 2. Different from traditional direct liquid-phase reduction, the present invention does not add any surfactants, effectively utilizes the disproportionation reaction of the intermediate product Cu2O to precipitate Cu elemental, and uses copper sulfate solution and NaBH4 ethanol to regulate the disproportionation reaction rate to assist the growth of Cu elemental nanocrystals into nanoflower structures. The Cu nanoflowers without surfactants retain the active sites to the greatest extent, which helps to optimize their application performance.

[0026] 3. The obtained elemental Cu nanoflowers have a large specific surface area and excellent electrocatalytic performance, and have good selectivity when used for the detection of sugar substances in cola. Description of the Drawings

[0027] Figure 1 is the X-ray diffraction pattern of the sample obtained in Example 1 of the present invention.

[0028] Figure 2 is the field emission scanning electron microscope image of the sample obtained in Example 1 of the present invention.

[0029] Figure 3 is the chronoamperometric response curve of the electrode constructed in Example 2 of the present invention in different concentrations of Coca-Cola.

[0030] Figure 4 It is the fitting linear equation of the response current density of the electrode constructed in the second embodiment of the present invention in Coca-Cola with different concentrations.

[0031] Figure 5 It is the response current of the electrode constructed in the first comparative example of the present invention in Coca-Cola with different concentrations.

[0032] Figure 6 It is the field emission scanning electron microscope image of the sample obtained in the second comparative example of the present invention.

[0033] Figure 7 It is the field emission scanning electron microscope image of the sample obtained in the third comparative example of the present invention.

[0034] Figure 8 It is the field emission scanning electron microscope image of the sample obtained in the fourth comparative example of the present invention.

[0035] Figure 9 It is the X-ray diffraction pattern of the sample obtained in the fourth comparative example of the present invention. Detailed implementation manners

[0036] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] Example 1: Preparation of Cu nanoflowers

[0038] (1) Prepare a copper sulfate solution with a volume of 22 mL and a concentration of 8.9 mg / mL. Sequentially add 428 mg of sodium citrate, 570 mg of sodium carbonate, and 1400 mg of potassium bromide powder. After stirring evenly, place it in a water bath at 70 °C. Add a glucose solution with a volume of 3.4 mL and a concentration of 297 mg / mL. After reacting for 5 minutes, take it out to obtain an orange precipitate, and filter it with filter paper;

[0039] (2) Dissolve the filtered orange powder in a copper sulfate aqueous solution with a concentration of 50 mg / mL and a volume of 2.5 mL, and ultrasonicate for 10 minutes to uniformly disperse the orange powder to obtain mixture 1;

[0040] (3) Add a sodium borohydride ethanol solution with a volume of 2.5 mL and a concentration of 10 mg / mL to mixture 1 to obtain mixture 2;

[0041] (4) Stir mixture 2 and react at room temperature for 2 hours to obtain a gray precipitate. After centrifugal separation, wash it once with deionized water and ethanol, and then perform centrifugal separation again and dry it in a blast drying oven at 80 °C. The obtained product is Cu nanoflowers.

[0042] In order to explore the composition of the obtained product, we conducted an X-ray diffraction test on the obtained sample, and the results are as follows Figure 1 As shown. Figure 1 It can be seen that the X-ray diffraction peaks of the obtained sample correspond to the Cu standard diffraction JCPDS card (89-2838). Among them, the diffraction peaks of about 43 degrees, 50 degrees, and 73 degrees correspond to the (111), (200), and (220) crystal planes of Cu elemental, respectively. In addition, the product does not contain other characteristic peaks such as Cu2O and CuO. This proves that the obtained product is a high-purity Cu elemental nanocrystal.

[0043] In order to explore the morphology of the obtained product, we measured the field emission scanning electron microscope of the sample obtained in Example 1, as shown in the attached manual. Figure 2 As shown, the obtained sample is a nanoflower layered structure, and the size of a single layered structure is 200-400nm. Compared with traditional nanoparticles, the nanoflower layered structure has a higher specific surface area, which helps to enhance its nano effect.

[0044] The orange precipitate in step (1) of the entire preparation is Cu2O. In step 4, the intermediate product Cu2O undergoes a disproportionation reaction, and a portion of the generated Cu element (i.e., Cu nanoflowers) and another portion of the generated divalent Cu ions are dissolved in the solution.

[0045] In step (3), sodium borohydride ethanol solution is used as a reducing agent to reduce the divalent Cu ions in the reducing solution to 1-valent Cu ions, thereby promoting the disproportionation reaction and promoting the nucleation of Cu element.

[0046] The copper sulfate solution in step (2) controls the rate of the disproportionation reaction by providing a large amount of soluble divalent Cu ions, prevents the rapid ripening of Cu elemental nucleation, controls the reaction kinetics, and assists the formation of Cu nanoflower structures.

[0047] Example 2: Detection of sugar content in cola 1

[0048] The Cu nanoflower obtained by the present invention can be used to determine the sugar content in cola, and the specific method is as follows:

[0049] (1) Stir Coca-Cola (with sugar) at room temperature for 2 hours. After the carbonic acid is completely decomposed, add KOH powder and adjust the pH of the solution to 14.0;

[0050] (2) Using deionized water, the Cu nanoflower powder obtained in Example 1 was configured into a suspension. 12 micrograms of the suspension was taken and deposited on a glassy carbon working electrode with a diameter of 3 mm (1.69 micrograms of Cu nanoflowers were deposited per square millimeter). After the liquid evaporated, the original Cu nanoflowers were completely modified on the glassy carbon working electrode. Then, 6 μL of a perfluorosulfonic acid-based polymer solution with a concentration of 0.05% was added dropwise. After the liquid evaporated, a proton exchange membrane was formed, which could be used as a modified electrode. Using Ag / AgCl as the reference electrode and a Pt wire electrode as the counter electrode, an electrochemical workstation was connected to measure the chronoamperometric response curve;

[0051] (3) Using a 1 mol / L KOH solution, the concentration of cola was successively diluted to 10%, 7.5%, 5%, and 2.5%. The working potential was set (1.1 V vs Ag / AgCl), and the chronoamperometric response curves at different concentrations were continuously measured;

[0052] (4) The linear function relationship between the response current density and the concentration was statistically analyzed, and a linear equation was fitted;

[0053] (5) The response current in the range of any cola concentration from 2.5% to 10% was measured, and the cola concentration was calculated using the linear equation to estimate the sugar content in the solution.

[0054] In step 3 - 4) of Example 2, the detection steps were based on the electrocatalysis of Cu nanoflowers for the oxidation of sugar substances in cola.

[0055] As Figure 3 shown: As the concentration of Coca - Cola was diluted from 10% to 2.5%, the sugar substances in the solution decreased synchronously, the charge participating in the oxidation reaction decreased, and the response current decreased linearly.

[0056] As Figure 4 shown, the response current density has a linear relationship with the concentration of the cola solution, and its fitting equation is 310.4 (%)X + 8947 = Y (μA / cm 2 ). The linear fitting degree is: 0.999. The slope is 310.4, and its detection sensitivity value for sugary cola is 3.104×10 -2 μA / cm 2 ·ppm. The relatively high sensitivity stems from the relatively high specific surface area of Cu nanoflowers.

[0057] Using the above equation, we can calculate the cola concentration (X - axis coordinate value) based on the measured response current (Y - axis coordinate value) at any concentration, and predict the sugar content in cola according to the sugar content in the original cola solution by percentage.

[0058] Comparative Example 1: Detection of sugar - free cola (selective proof)

[0059] The method for detecting sugar in cola provided by the present invention has good selectivity. In order to verify that the change in the response current at the working potential comes from the change in sugar in cola (rather than other ingredients), the following comparative example is carried out, and the specific operation steps are as follows:

[0060] (1) Stir sugar-free Coca-Cola at room temperature for 2 hours. After the carbonic acid is completely decomposed, add KOH powder and adjust the solution pH to 14.0;

[0061] (2) Using deionized water, the Cu nanoflower powder obtained in Example 1 was prepared into a suspension, and 12 μg of the suspension was deposited on a glassy carbon working electrode with a diameter of 3 mm (1.69 μg of Cu nanoflowers were deposited per square millimeter). After the liquid evaporated, the original Cu nanoflowers were completely modified on the glassy carbon working electrode, and then 6 μL of a 0.05% perfluorosulfonic acid polymer solution was added dropwise. After the liquid evaporated, a proton exchange membrane was formed, which could be used as a modified electrode. Ag / AgCl was used as a reference electrode, and a Pt wire electrode was used as a counter electrode. The electrochemical workstation was connected to measure the chronoamperometric response curve;

[0062] (3) Using 1 mol / L KOH, the concentration of sugar-free cola was diluted to 10%, 7.5%, 5%, and 2.5%, and the working potential was set (1.1 V vs Ag / AgCl), and the chrono-response current curves at different concentrations were continuously measured;

[0063] (4) Statistical response current density and concentration linear function relationship, fitting linear equation;

[0064] (5) Measure the response current within the range of 2.5-10% cola concentration, calculate the cola concentration using a linear equation, and estimate the sugar content in the solution.

[0065] Compared with Example 2, the sugar-containing Coca-Cola in Comparative Example 1 was replaced with sugar-free Coke. Figure 5 As shown in the figure, compared with ordinary cola with sugar, the response current of sugar-free cola with the same concentration is only 12.8% of that of sugar-free cola. In addition, with the dilution of the concentration of sugar-free cola, the response current does not change significantly. This shows that the change in the response current in the cola detected by the present invention is caused by the change in the sugar concentration in the cola, and has nothing to do with other ingredients in the cola. The detection method has good selectivity.

[0066] Comparative Example 2: Key Parameter 1 (Effect of Sodium Borohydride Concentration on Product Morphology)

[0067] In the present invention, the concentration of sodium borohydride plays a crucial role in the morphology of Cu nanocrystals. When the concentration of NaBH4 is too high, it will consume divalent Cu ions itself, accelerating the disproportionation reaction of the obtained Cu2O, thereby destroying the morphology of Cu nanoflowers. To confirm this view, the following comparative examples are presented, and the specific operation steps are as follows:

[0068] (1) Prepare a copper sulfate solution with a volume of 22 mL and a concentration of 8.9 mg / mL. Sequentially add 428 mg of sodium citrate, 570 mg of sodium carbonate, and 1400 mg of potassium bromide powder. After stirring evenly, place it in a water bath at 70 degrees Celsius. Add a glucose solution with a volume of 3.4 mL and a concentration of 297 mg / mL. After reacting for 5 minutes, take it out to obtain an orange precipitate, and filter it with filter paper;

[0069] (2) Dissolve the filtered orange solid powder in a 2.5 mL aqueous CuSO4 solution with a concentration of 50 mg / mL, and ultrasonicate for 10 minutes to evenly disperse the orange solid powder to obtain mixture 1;

[0070] (3) Add a 2.5 mL NaBH4 ethanol solution with a concentration of 20 mg / mL to mixture 1 to obtain mixture 2;

[0071] (4) Stir mixture 2. After reacting at room temperature for 2 hours, the obtained product is centrifuged, washed once with deionized water and ethanol, and then centrifuged again and dried in a blast drying oven at 80 °C.

[0072] Compared with Example 1, in Comparative Example 2, the concentration of the NaBH4 ethanol solution was increased from 10 mg / mL to 20 mg / mL. To explore the morphology of the obtained sample, we tested the scanning electron microscope of the sample obtained in Comparative Example 2. As Figure 6 shown, the obtained sample has a morphology of nanoparticles with a diameter of 150 - 200 nm.

[0073] It can be obtained therefrom that one of the key parameters for the preparation of the present invention is to control the concentration of the NaBH4 ethanol solution. When the concentration of the NaBH4 ethanol solution increases, divalent Cu ions are rapidly reduced to Cu2O, resulting in an accelerated further disproportionation reaction of Cu2O. Too fast a reaction is likely to form a nanoparticle structure, which is not conducive to the formation of the Cu nanoflower structure.

[0074] Comparative Example 3: Key Parameter 2 (Effect of Sodium Borohydride Ethanol Solution on Product Morphology)

[0075] One of the key technical parameters of the present invention is to prepare a NaBH4 solution using ethanol. To confirm this view, the following comparative examples are presented, and the specific operation steps are as follows:

[0076] (1) Prepare a copper sulfate solution with a volume of 22 mL and a concentration of 8.9 mg / mL. Sequentially add 428 mg of sodium citrate, 570 mg of sodium carbonate, and 1400 mg of potassium bromide powder. After stirring evenly, place it in a water bath at 70 °C, add a glucose solution with a volume of 3.4 mL and a concentration of 297 mg / mL. After reacting for 5 minutes, take it out to obtain an orange precipitate, and filter it with filter paper;

[0077] (2) Dissolve the filtered orange solid powder in an aqueous copper sulfate solution with a concentration of 50 mg / mL and a volume of 2.5 mL, and ultrasonicate for 10 minutes to uniformly disperse the orange solid powder to obtain mixture 1;

[0078] (3) Add a 2.5 mL aqueous NaBH4 solution with a concentration of 10 mg / mL to mixture 1 to obtain mixture 2;

[0079] (4) Stir mixture 2, and after reacting at room temperature for 2 hours, the obtained product is centrifuged, washed once with deionized water and ethanol, and then centrifuged again and dried in a blast drying oven at 80 °C.

[0080] Compared with Example 1, in Comparative Example 3, the "NaBH4 ethanol solution" in step (3) was changed to "NaBH4 aqueous solution". In order to explore the morphology of the obtained sample, we tested the scanning electron microscope of the sample obtained in Comparative Example 3. As Figure 7 shown, the obtained sample failed to form a nanoflower structure.

[0081] It can be concluded that: The second key parameter of the preparation method of the present invention is to prepare the NaBH4 solution with an ethanol solution. NaBH4 is slightly soluble in ethanol solution. In an aqueous solution, the dissolution of NaBH4 increases, resulting in an accelerated reaction. An overly fast reaction is prone to forming a nanoparticle structure, which is not conducive to the formation of the Cu nanoflower structure.

[0082] Comparative Example 4: Key Parameter 3 (Effect of Preparation Step 1 on the Product)

[0083] In the present invention, the orange powder obtained in preparation step 1 is Cu2O, and the disproportionation reaction of Cu2O is the key to obtaining Cu single crystal nanoflowers in this patent. To confirm this view, the following comparative examples are presented, and the specific operation steps are as follows:

[0084] (1) Prepare an aqueous copper sulfate solution with a concentration of 50 mg / mL and a volume of 2.5 mL, and ultrasonicate for 10 minutes to obtain mixture 1;

[0085] (2) Add a 2.5 mL NaBH4 ethanol solution with a concentration of 10 mg / mL to mixture 1 to obtain mixture 2;

[0086] (3) Stir the mixed solution 2, and after reacting for 2 hours at room temperature, the obtained product is centrifuged, washed once with deionized water and ethanol, and then centrifuged again and dried in a blast drying oven at 80 °C.

[0087] Compared with Example 1, in Comparative Example 4, step (1) of Example 1, "Prepare a copper sulfate solution with a volume of 22 mL and a concentration of 8.9 mg / mL, and successively add 428 mg of sodium citrate, 570 mg of sodium carbonate, and 1400 mg of potassium bromide powder. After stirring evenly, place it in a water bath at 70 °C, add a glucose solution with a volume of 3.4 mL and a concentration of 297 mg / mL, take it out after reacting for 5 minutes to obtain an orange precipitate, and filter it with filter paper" was deleted.

[0088] To explore the morphology of the obtained sample, we tested the scanning electron microscope of the sample obtained in Comparative Example 4. As Figure 8 shown, the obtained sample failed to form a nanoflower structure. To explore the components of the obtained sample, we tested the X-ray diffraction pattern of the sample obtained in Comparative Example 4. As Figure 9 shown, the obtained sample is not elemental Cu, but a mixture of Cu2O and elemental Cu. This proves that the target product cannot be obtained simply by mixing sodium borohydride ethanol and an aqueous copper sulfate solution. Step 1 of the preparation method of the present invention is the key parameter for preparing Cu nanoflowers.

[0089] In summary, this article provides a preparation method of Cu nanoflowers and is used for detecting the sugar content of cola. It should be noted that the above is the preferred implementation mode of the invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. Application of Cu nanoflowers in the detection of cola sugar content, characterized in that, The method for detecting the sugar content of cola using Cu nanoflowers is as follows: (1) Stir the cola at room temperature for 2 hours. After its carbonic acid is completely decomposed, add KOH powder and adjust the pH of the solution to 14.0; (2) Use deionized water to prepare a suspension of Cu nanoflowers. Take a certain mass of the suspension and deposit it on a glassy carbon working electrode. The mass of the deposited Cu nanoflowers is 1.65 to 1.70 micrograms. After the liquid evaporates, then dropwise add a perfluorosulfonic acid polymer solution with a concentration of 0.05%. The modified electrode is used as the working electrode, Ag / AgCl is used as the reference electrode, and a Pt wire electrode is used as the counter electrode. Connect an electrochemical workstation to measure the chronoamperometric response current curve; (3) Dilute the cola solution with a KOH solution with a concentration of 1 mol / L, set the working potential, and continuously measure the chronoamperometric response curves at different concentrations; (4) According to the functional relationship between the response current density and the cola concentration, fit a linear equation; (5) Measure the response current of any cola concentration to be measured, and use the linear fitting equation to calculate the sugar content in the cola solution; Among them, the preparation method steps of the used Cu nanoflowers are as follows: (1) Prepare a copper sulfate solution with a concentration of 8.9 mg / mL. Add sodium citrate, sodium carbonate, and potassium bromide powder in sequence according to the ratio. After stirring evenly, place it in a water bath at 70 degrees Celsius. Add a glucose solution with a concentration of 297 mg / mL. After reacting for 4 - 5 minutes, take it out to obtain an orange precipitate, and filter it with filter paper; (2) Dissolve the filtered orange powder in a copper sulfate aqueous solution with a concentration of 50 mg / mL according to the ratio, and obtain mixture 1 after ultrasonic dispersion; (3) Add a sodium borohydride ethanol solution with a concentration of 10 mg / mL to mixture 1 according to the ratio to obtain mixture 2; (4) Stir mixture 2. After reacting at room temperature for 2 hours, obtain a gray precipitate. Centrifuge it, then wash it 1 - 2 times with deionized water and ethanol, centrifuge it again, and finally dry it in a blast dryer. The obtained powder is Cu nanoflowers; In step (1), the added sodium citrate is 19 - 20 milligrams of sodium citrate per milliliter of copper sulfate aqueous solution; the concentration ratio of the added sodium carbonate to the copper sulfate solution is 25 - 26 milligrams of sodium carbonate per milliliter of CuSO4 aqueous solution; the concentration ratio of the added potassium bromide powder to the copper sulfate solution is 62 - 64 milligrams per milliliter of CuSO4 aqueous solution; the volume ratio of the added glucose to the copper sulfate solution is 17:110; The ratio of the copper sulfate aqueous solution in step (2) to the copper sulfate aqueous solution in step (1) is 5:44; In step (3), the volume ratio of mixture 1 to the sodium borohydride ethanol solution is 1:1.

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