Microwave method for preparing micro-nano copper oxide powder and application thereof

Abstract

The application discloses a method for preparing micro-nano copper oxide powder by a microwave method and application thereof, and comprises the following steps: a) preparing a copper ion solution; b) adding a dispersing agent and a surfactant; c) adding urea; d) microwave heating reaction; e) product separation and purification; and f) drying and calcination. The application utilizes the rapid heating characteristics of microwave radiation, combines the action of urea, adds a dispersing agent such as polyvinylpyrrolidone (PVP) and a surfactant in the copper ion solution, and prepares copper oxide nanoparticles with a particle size distribution of 50-100 nanometers and even controllable micron level, and the copper oxide nanoparticles have good crystal structure and dispersibility; and the method has the advantages of simple process, fast reaction speed and low energy consumption, and the obtained copper oxide nanoparticles can be used for preparing high-performance and high-purity copper oxide nanomaterials, and have wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, and in particular to a method for preparing micro / nano copper oxide powder using a microwave method and its application. Background Technology

[0002] Copper oxide (CuO) is an important transition metal oxide with unique physical and chemical properties, such as narrow bandgap semiconductor properties, excellent catalytic activity, optical properties, and thermal stability. Therefore, CuO nanomaterials have wide applications in photocatalysis, batteries, gas sensors, magnetic materials, and electronic devices.

[0003] Currently, methods for preparing CuO nanomaterials include sol-gel method, hydrothermal / solvothermal method, microemulsion method, chemical precipitation method, and thermal decomposition method.

[0004] However, these traditional methods have the following problems:

[0005] 1. Harsh reaction conditions: High-temperature and high-pressure equipment is required, which increases the complexity and danger of the experiment;

[0006] 2. Long reaction time: The preparation process is time-consuming, which affects production efficiency;

[0007] 3. Difficulty in controlling particle size: It is difficult to achieve precise control over the size and morphology of nanoparticles;

[0008] 4. Poor dispersibility: It is prone to agglomeration, which affects the material properties;

[0009] Therefore, developing a method for preparing CuO nanoparticles with mild reaction conditions, simple process, rapid reaction, and controllable particle size and morphology is of great research value and practical significance, and is also a technical problem that urgently needs to be solved in this invention. Summary of the Invention

[0010] In view of this, the present invention provides a method for preparing micro / nano copper oxide powder by microwave method and its application.

[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0012] A method for preparing micro / nano copper oxide powder using microwave method includes the following steps:

[0013] a) Preparation of copper ion solution: Dissolve soluble copper salt in deionized water to obtain copper ion solution;

[0014] b) Add dispersant and surfactant: Add dispersant and surfactant to the copper ion solution in step a), stir until homogeneous, and form a clear solution;

[0015] c) Add urea: Add urea in proportion while stirring, and continue stirring to obtain the reaction mixture;

[0016] d) Microwave heating reaction: The reaction mixture from step c) is transferred to a microwave reaction vessel and heated;

[0017] e) Product separation and purification: After the reaction is complete, cool, centrifuge to separate the product, wash and remove impurities;

[0018] f) Drying and calcination: The product is dried at low temperature and then calcined to obtain micro-nano copper oxide powder.

[0019] Preferably, in step a), the soluble copper salt is one or more of copper acetate, copper nitrate, or copper sulfate.

[0020] Preferably, in step b), the dispersant is polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG).

[0021] Preferably, in step b), the surfactant is sodium dodecyl sulfate (SDS) or Tween 80.

[0022] Preferably, in step c), the molar ratio of urea to copper ions is 1:1 to 5:1.

[0023] Preferably, in step d), the microwave power is 400-800W, the heating time at the microwave power is 1-10 minutes, and the microwave heating temperature is 60-100℃.

[0024] Preferably, in step e), the washing is performed by repeatedly washing three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0025] Preferably, in step f), the low-temperature drying temperature is 60-70°C and the drying time is 10-12 hours; the calcination temperature is 300-400°C and the calcination time is 2 hours.

[0026] Preferably, in step f), the copper oxide nanoparticles have a particle size distribution of 50-100 nanometers.

[0027] An application of a microwave method for preparing micro / nano copper oxide powder in gas sensors: using copper oxide nanoparticles as a sensitive material, it can be used to detect toxic gases such as formaldehyde, carbon monoxide, and ammonia.

[0028] The present invention achieves the following technical effects compared to the prior art:

[0029] (1) This invention achieves continuous and controllable synthesis of nanoscale 50-100nm to micron-scale particles by synergistic adjustment of urea addition molar ratio of 1:1 to 5:1 and microwave power of 400-800W, breaking through the problem of wide particle size distribution in traditional methods, and the controllable copper oxide nanoparticles down to the micron level have good crystal structure and dispersibility.

[0030] (2) The present invention uses microwave-assisted synthesis, which utilizes its rapid and uniform heating characteristics to significantly shorten the reaction time to 5-10 minutes compared with the traditional hydrothermal method, and has significant efficiency advantages. The method of the present invention is simple, fast, and low in energy consumption. The obtained copper oxide nanoparticles can be used to prepare high-performance, high-purity copper oxide nanomaterials and have broad application prospects.

[0031] (3) The present invention utilizes a multi-component dispersant combination of PVP / SDS / PEG to achieve better particle dispersibility (PDI<0.2) than a single dispersant system (PDI>0.3);

[0032] (4) The urea of ​​the present invention plays a dual role. In the reaction, urea acts as a precipitant to promote the precipitation of copper ions, and also generates OH- through hydrolysis, which adjusts the pH value of the solution and is conducive to the formation of copper oxide.

[0033] (5) The particle size and morphology of the present invention are controllable. By adjusting the reaction conditions, such as microwave power, reaction time, ratio of urea and copper salt, type and amount of dispersant, the particle size and morphology of copper oxide nanoparticles can be controlled.

[0034] (6) The process of the present invention is simple and environmentally friendly, the reaction conditions are mild and the process is simple, no high temperature and high pressure equipment is required, and no harmful substances are generated during the reaction process, which is in line with the concept of green chemistry.

[0035] (7) The preparation method of the present invention has many industrial application values. For example, in the field of catalysis, it can be used as a catalyst or co-catalyst in catalytic oxidation, methanol reforming and other catalytic reactions; in the field of gas sensors, it has sensitive characteristics to certain gases and can be used to prepare highly sensitive gas sensors to detect toxic gases in the environment; in the field of lithium-ion battery materials, it can be used as a negative electrode material for lithium-ion batteries, with high specific capacity and excellent cycle performance; in the field of optical materials, it has good absorption performance in the visible light region and can be used in photodetectors, solar cells and other fields. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating a microwave method for preparing micro / nano copper oxide powder and its application.

[0037] Figure 2This is a SEM image of nano-copper oxide, showing a microwave method for preparing micro / nano copper oxide powder and its application according to the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] This invention discloses a method for preparing micro / nano copper oxide powder using a microwave method, comprising the following steps:

[0040] a) Preparation of copper ion solution: Dissolve soluble copper salt in deionized water to obtain copper ion solution;

[0041] b) Add dispersant and surfactant: Add dispersant and surfactant to the copper ion solution in step a), stir until homogeneous, and form a clear solution;

[0042] c) Add urea: Add urea in proportion while stirring, and continue stirring to obtain the reaction mixture;

[0043] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel. The microwave power is 400-800W, the heating time is 1-10 minutes, and the microwave heating temperature is 60-100℃.

[0044] e) Product separation and purification: After the reaction is complete, cool and centrifuge to separate the product. Wash the product three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0045] f) Drying and calcination: The product is dried at a low temperature of 60-70℃ for 10-12 hours, and then calcined at 300-400℃ for 2 hours to obtain micro-nano copper oxide powder with a particle size distribution of 50-100 nanometers.

[0046] The soluble copper salt is one or more of copper acetate, copper nitrate, or copper sulfate.

[0047] The dispersant is polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG).

[0048] The surfactant is sodium dodecyl sulfate (SDS) or Tween 80.

[0049] The molar ratio of urea to copper ions is 1:1 to 5:1.

[0050] This invention also discloses the application of a microwave method for preparing micro / nano copper oxide powder in gas sensors. Copper oxide nanoparticles are used as sensitive materials to detect toxic gases such as formaldehyde, carbon monoxide, and ammonia.

[0051] Example 1: Preparation of nano-copper oxide powder using copper acetate as the copper source

[0052] 1. Reagents and materials:

[0053] Copper source: Copper acetate monohydrate (Cu(CH3COO)2·H2O), analytical grade;

[0054] Urea: analytical grade;

[0055] Dispersant: Polyvinylpyrrolidone (PVP, K30), analytical grade;

[0056] Solvent: Deionized water;

[0057] 2. Preparation steps:

[0058] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0059] b) Add dispersant: Add 1.0 g of PVP to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0060] c) Add urea: Add 3.0 g of urea while stirring, and continue stirring for 15 minutes. The solution remains clear, and the reaction mixture is obtained.

[0061] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0062] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0063] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder.

[0064] 3. Result characterization:

[0065] Particle size analysis: Transmission electron microscopy (TEM) revealed that the copper oxide nanoparticles were regular rod-shaped, with a length of approximately 80-100 nm and a width of approximately 20-30 nm.

[0066] Crystal structure: X-ray diffraction (XRD) tests showed that the product is a monoclinic CuO with sharp peaks and high crystallinity.

[0067] Specific surface area: According to BET testing, the specific surface area of ​​copper oxide nanoparticles is 25 m². 2 / g.

[0068] As shown in Tables 1 and 2;

[0069] Table 1:

[0070] parameter Test methods Typical value (Example 1) initial pH of solution pH meter 3.2±0.1 Reaction endpoint pH pH meter 6.8±0.3 OH- formation rate Acid-base titration 0.12 mmol / min Crystal nucleation time DLS Dynamic Light Scattering 90±15 seconds

[0071] Table 2:

[0072] Performance indicators Test conditions Example 1 Data Compare with literature values ​​(hydrothermal method) Specific surface area (BET) <![CDATA[N2 adsorption, 77K]]> <![CDATA[38.5m 2 / g]]> <![CDATA[25-30m 2 / g]]> Aperture distribution BJH method Mainly mesoporous, 4-6nm Irregular aperture electrical conductivity Four-probe method, 25℃ <![CDATA[1.2×10 -3 S / cm]]> <![CDATA[5×10 -4 S / cm]]> Thermal stability (TGA) Atmospheric temperature, 10℃ / min Weight loss <2% @ 400℃ Weight loss 5-8% @ 400℃ .

[0073] Example 2: Preparation of micron-sized copper oxide powder using copper nitrate as the copper source

[0074] 1. Reagents and materials:

[0075] Copper source: Copper nitrate trihydrate (Cu(NO3)2·3H2O), analytical grade;

[0076] Urea: analytical grade;

[0077] Dispersant: Polyethylene glycol (PEG400), analytical grade;

[0078] Surfactant: Sodium dodecyl sulfate (SDS), analytical grade;

[0079] Solvent: Deionized water.

[0080] 2. Preparation steps:

[0081] a) Preparation of copper ion solution: Weigh 2.0 g of copper nitrate and dissolve it in 200 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0082] b) Add dispersant and surfactant: Add 2.0 g of PEG400 and 0.5 g of SDS to the copper ion solution in step a), and stir until completely dissolved to form a uniform blue solution;

[0083] c) Add urea: Add 6.0 g of urea while stirring, and continue stirring for 10 minutes to obtain the reaction mixture;

[0084] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 700W, the reaction time to 8 minutes, and the temperature to 95℃.

[0085] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0086] f) Drying and calcination: The product was placed in an oven and dried at 70°C for 10 hours; then calcined in air at 400°C for 2 hours to obtain micron-sized copper oxide powder.

[0087] 3. Result characterization:

[0088] Particle size analysis: Scanning electron microscopy (SEM) revealed that the copper oxide particles were flaky with a diameter of approximately 12 micrometers and relatively uniform size.

[0089] Crystal structure: XRD test showed that the product is monoclinic CuO with no impurity peaks and good crystallinity;

[0090] Example 3: Preparation of micron-sized copper oxide powder using copper nitrate as the copper source

[0091] 1. Reagents and materials:

[0092] Copper source: Copper nitrate trihydrate (Cu(NO3)2·3H2O), analytical grade;

[0093] Urea: analytical grade;

[0094] Dispersant: Polyethylene glycol (PEG400), analytical grade;

[0095] Solvent: Deionized water.

[0096] 2. Preparation steps:

[0097] a) Preparation of copper ion solution: Weigh 2.0 g of copper nitrate and dissolve it in 200 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0098] b) Add dispersant and surfactant: Add 2.0 g of PEG400 to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0099] c) Add urea: Add 6.0 g of urea while stirring, and continue stirring for 10 minutes to obtain the reaction mixture;

[0100] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 700W, the reaction time to 8 minutes, and the temperature to 95℃.

[0101] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0102] f) Drying and calcination: The product was placed in an oven and dried at 70°C for 10 hours; then calcined in air at 400°C for 2 hours to obtain micron-sized copper oxide powder.

[0103] As can be seen from Examples 1-3 above, different dispersants and surfactants have a significant impact on the morphology and dispersibility of particles. Among them, the use of PVP is beneficial for the formation of uniform nanoparticles and prevents agglomeration; the use of PEG400 can promote particle growth and form larger particles; the addition of SDS can adjust the morphology of particles and form plate-like or rod-like structures.

[0104] Therefore, by selecting appropriate dispersants and surfactants, the morphology and particle size of copper oxide nanoparticles can be controlled.

[0105] Example 4: Effect of reaction conditions on the particle size of copper oxide particles

[0106] 1. Experimental Design:

[0107] While keeping the copper salt concentration constant, the molar ratio of urea to copper ions was changed, and the changes in particle size were observed.

[0108] 2. Preparation steps: (one)

[0110] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0111] b) Add dispersant and surfactant: Add 1.0 g of PVP and 0.3 g of SDS to the copper ion solution in step a), and stir until completely dissolved to form a uniform blue solution;

[0112] c) Add urea: Add 1.0 g of urea while stirring, and continue stirring for 15 minutes to obtain the reaction mixture;

[0113] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0114] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0115] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder. (two)

[0117] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0118] b) Add dispersant and surfactant: Add 1.0 g of PVP and 0.3 g of SDS to the copper ion solution in step a), and stir until completely dissolved to form a uniform blue solution;

[0119] c) Add urea: Add 2.0 g of urea while stirring, and continue stirring for 15 minutes to obtain the reaction mixture;

[0120] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0121] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0122] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder. (three)

[0124] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0125] b) Add dispersant and surfactant: Add 1.0 g of PVP and 0.3 g of SDS to the copper ion solution in step a), and stir until completely dissolved to form a uniform blue solution;

[0126] c) Add urea: Add 3.0 g of urea while stirring, and continue stirring for 15 minutes to obtain the reaction mixture;

[0127] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0128] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0129] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder.

[0130] 3. Results Analysis:

[0131] When the molar ratio of urea to copper ions is 1:1, with 1 gram of urea and 1 gram of copper ions, the particle size is about 30 to 50 nanometers. The particle size is small, but the dispersibility is slightly poor and there is slight agglomeration.

[0132] When the molar ratio of urea to copper ions is 2:1, with 2 grams of urea and 1 gram of copper ions, the particle size is about 50 to 80 nanometers, with good dispersibility and regular morphology.

[0133] When the molar ratio of urea to copper ions is 3:1, with 3 grams of urea and 1 gram of copper ions, the particle size increases to approximately 80–100 nanometers, and the morphology is rod-shaped or plate-shaped.

[0134] Therefore, it can be seen that by adjusting the ratio of urea to copper ions, the size and morphology of copper oxide nanoparticles can be effectively controlled; appropriately increasing the amount of urea is beneficial to obtaining larger particles.

[0135] Example 5: Application of copper oxide nanoparticles in gas sensors

[0136] 1. Sensor fabrication method steps:

[0137] a) The copper oxide nanopowder prepared in Example 1 was dispersed in an ethanol solution and ultrasonically treated for 30 minutes to obtain a uniform suspension;

[0138] b) The suspension was coated onto a ceramic substrate, dried, and then calcined at 300°C for 1 hour to form a copper oxide sensitive film;

[0139] 2. Sensor performance test:

[0140] In a formaldehyde gas environment of a certain concentration, the gas sensor exhibits high sensitivity and fast response performance, indicating that the prepared copper oxide nanoparticles have excellent gas-sensing properties.

[0141] Example 6: Effect of microwave power on copper oxide particles

[0142] 1. Experimental Design:

[0143] Under the same conditions, change the microwave power;

[0144] 2. Preparation steps: (one)

[0146] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0147] b) Add dispersant: Add 1.0 g of PVP to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0148] c) Add urea: Add 3.0 g of urea while stirring, and continue stirring for 15 minutes. The solution remains clear, and the reaction mixture is obtained.

[0149] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 400W, the reaction time to 5 minutes, and the temperature to 90℃.

[0150] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0151] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder. (two)

[0153] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0154] b) Add dispersant: Add 1.0 g of PVP to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0155] c) Add urea: Add 3.0 g of urea while stirring, and continue stirring for 15 minutes. The solution remains clear, and the reaction mixture is obtained.

[0156] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0157] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0158] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder. (three)

[0160] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0161] b) Add dispersant: Add 1.0 g of PVP to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0162] c) Add urea: Add 3.0 g of urea while stirring, and continue stirring for 15 minutes. The solution remains clear, and the reaction mixture is obtained.

[0163] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 800W, the reaction time to 5 minutes, and the temperature to 90℃.

[0164] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0165] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder.

[0166] 3. Results Analysis:

[0167] When the microwave power is 400W, the reaction is incomplete, and the resulting copper oxide particles are large in size and unevenly distributed.

[0168] When the microwave power is 600W, uniformly sized copper oxide nanoparticles with a particle size of about 50 to 80 nanometers can be obtained.

[0169] When the microwave power is 800W, the reaction is too fast, which can easily lead to particle agglomeration and increase the particle size to more than 100 nanometers.

[0170] Therefore, by selecting an appropriate microwave power, such as 600W, copper oxide nanoparticles with uniform particle size and good dispersibility can be obtained.

[0171] Example 7: Effect of urea dosage on particle size

[0172] 1. Experimental Design:

[0173] Under the same conditions, increase the amount of urea used;

[0174] 2. Preparation steps: (one)

[0176] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0177] b) Add dispersant: Add 1.0 g of PVP to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0178] c) Add urea: Add 1.0 g of urea while stirring, and continue stirring for 15 minutes. The solution remains clear, and the reaction mixture is obtained.

[0179] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0180] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0181] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder. (two)

[0183] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0184] b) Add dispersant: Add 1.0 g of PVP to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0185] c) Add urea: Add 3.0 g of urea while stirring, and continue stirring for 15 minutes. The solution remains clear, and the reaction mixture is obtained.

[0186] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0187] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0188] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder. (three)

[0190] a) Preparation of copper ion solution: Weigh 1.0 g of copper acetate and dissolve it in 100 mL of deionized water to obtain a copper ion solution of about 50 mmol / L;

[0191] b) Add dispersant: Add 1.0 g of PVP to the copper ion solution in step a) and stir until completely dissolved to form a uniform blue solution;

[0192] c) Add urea: Add 5.0 g of urea while stirring, and continue stirring for 15 minutes. The solution remains clear, and the reaction mixture is obtained.

[0193] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600W, the reaction time to 5 minutes, and the temperature to 90℃.

[0194] e) Product separation and purification: After the reaction is complete, the product is cooled to room temperature and centrifuged at 8000 rpm for 10 minutes to separate the product. The product is washed three times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

[0195] f) Drying and calcination: The product was placed in an oven and dried at 60°C for 12 hours; then calcined at 300°C for 2 hours in air to obtain black copper oxide nanopowder.

[0196] 3. Results Analysis:

[0197] When the molar ratio of urea to copper ions is 1:1, the particle size is relatively small, about 30 to 50 nanometers.

[0198] When the molar ratio of urea to copper ions is 3:1, the particle size increases to 80-100 nanometers.

[0199] When the molar ratio of urea to copper ions is 5:1, the particles increase in size further, potentially forming micron-sized particles.

[0200] Therefore, increasing the amount of urea can promote the growth of copper oxide crystal nuclei and increase the particle size. At the same time, the buffering effect of urea is enhanced, and the pH value of the solution increases, which is conducive to the formation of copper oxide. By adjusting the molar ratio of urea to copper ions, the particle size of copper oxide nanoparticles can be controlled.

[0201] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing micro-nano copper oxide powder by microwave method, characterized in that, The method comprises the following steps: a) preparing a copper ion solution: dissolving a soluble copper salt in deionized water to obtain a copper ion solution; b) adding a dispersant and a surfactant: adding a dispersant and a surfactant to the copper ion solution of step a), stirring uniformly to form a clear solution; c) adding urea: adding urea in proportion under stirring, continuing to stir to obtain a reaction mixture; d) microwave heating reaction: transferring the reaction mixture of step c) to a microwave reaction container and heating; e) product separation and purification: after the reaction is completed, the product is cooled and centrifuged, washed and impurities are removed; f) drying and calcination: drying the product at low temperature and then calcining to obtain micro-nano copper oxide powder; In step b), the dispersant is polyvinylpyrrolidone PVP. In step c), the molar ratio of urea to copper ions is 1:1 to 5:

1. In step d), the microwave power is 400-800 W, the heating time under microwave power is 110 minutes, and the microwave heating temperature is 60-100℃.

2. The method for preparing micro-nano copper oxide powder by microwave method according to claim 1, characterized in that, In step a), the soluble copper salt is one or more of copper acetate, copper nitrate or copper sulfate.

3. The method for preparing micro-nano copper oxide powder by microwave method according to claim 1, characterized in that, In step b), the surfactant is sodium dodecyl sulfate SDS or Tween 80.

4. The method for preparing micro-nano copper oxide powder by microwave method according to claim 1, characterized in that, In step e), the washing is repeated 3 times with deionized water and anhydrous ethanol to remove unreacted reagents and impurities.

5. The method for preparing micro-nano copper oxide powder by microwave method according to claim 1, characterized in that, In step f), the drying temperature at low temperature is 60-70℃, and the drying time is 10-12 hours; the calcination temperature is 300-400℃, and the calcination time is 2 hours.

6. The method for preparing micro-nano copper oxide powder by microwave method according to claim 1, characterized in that, In step f), the particle size distribution of the copper oxide nanoparticles is 50-100 nanometers.

7. Use of the method for preparing micro-nano copper oxide powder by microwave method according to claims 1-6 in a gas sensor, characterized in that, The copper oxide nanoparticles are used as sensitive materials for detecting toxic gases such as formaldehyde, carbon monoxide and ammonia.

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