CN111659898A - Preparation method of micro-nano copper sheet - Google Patents

Abstract

The invention discloses a method for preparing micro-nano copper sheets, which comprises: collecting and obtaining plant biomass raw materials, processing the plant biomass raw materials to obtain plant biomass dry material or plant biomass leaching solution; providing water-soluble Dissolving copper salt in water to obtain a copper salt solution; transferring the copper salt solution to a reactor, adding the plant biomass dry material or the plant biomass leaching solution to the reactor; The reaction kettle is sealed and then subjected to a hydrothermal reaction, solid-liquid separation is performed to collect the solid reaction product, and by-products in the solid reaction product are separated and removed to prepare the micro-nano copper sheet. The preparation method of the micro-nano copper sheet provided by the invention has the advantages of simple process, low cost, environmental friendliness and the like.

Description

A kind of preparation method of micro-nano copper sheet

technical field

The invention belongs to the technical field of micro-nano-scale materials, and in particular relates to a preparation method of a micro-nano copper sheet.

Background technique

In recent years, low-dimensional nanomaterials, such as nanowires, nanofibers, nanorods, nanoribbons, and nanosheets/disks, have been widely used in nanoelectronic devices, biological Sensors, nanoprobes, nanochemistry, and nanocomposites. Among them, two-dimensional micro-nano copper sheets have attracted great attention due to their excellent electrical and thermal conductivity and antibacterial properties, and are widely used in lubricating materials, dielectric materials, catalysts, sensors, biomedicine, and flexible electronics.

At present, there are many methods for preparing micro-nano copper sheets, and the representative methods include physical mechanical ball milling and wet chemical reduction. The mechanical ball milling method is to extrude the ball powder into flakes by mechanical grinding. Although this method can easily realize the large-scale production of copper sheets, it cannot strictly control the shape and size, and the obtained micro-nano copper sheets have poor uniformity. In this method, various grinding aids such as lubricants are inevitably added, and the process is complicated. The wet chemical reduction method can realize the controllable preparation of micro-nano copper sheets by adding additives such as dispersants and structure-directing agents. However, due to the introduction of various additives, the separation and purification process of the final copper sheets is complicated, and at the same time This method is difficult to achieve large-scale production of copper sheets.

Existing methods for preparing micro-nano copper sheets inevitably require the addition of various additives, such as lubricants, dispersants, stabilizers, structure-directing agents, etc., to regulate the preparation of copper sheets, resulting in complex processes, high costs and serious environmental pollution.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing micro-nano copper sheets with simple process, low cost, and green macro-scale.

In order to realize the above-mentioned purpose of the invention, the present invention has adopted the following technical solutions:

A preparation method of micro-nano copper sheet, comprising:

collecting and obtaining plant biomass raw materials, and processing the plant biomass raw materials to obtain plant biomass dry material or plant biomass leachate;

Provide water-soluble copper salt and dissolve it in water to obtain copper salt solution;

The copper salt solution is transferred to the reactor, and the plant biomass dry material or the plant biomass leaching solution is added to the reactor;

The reaction kettle is sealed and then subjected to hydrothermal reaction, solid-liquid separation is performed to collect the solid-state reaction product, and by-products in the solid-state reaction product are separated and removed to prepare the micro-nano copper sheet.

Specifically, the plant biomass raw material is one or more of the roots, stems, branches, leaves, flowers, fruits and seeds of plants.

Specifically, the plant biomass raw material is selected from the biomass raw material of evergreen trees.

Specifically, the processing of the plant biomass raw material to obtain the plant biomass dry material includes: placing the plant biomass raw material in a roasting device for roasting to obtain the plant biomass dry material; the The processing of the plant biomass raw material to obtain the plant biomass leaching solution includes: placing the plant biomass raw material in a roasting device for roasting to obtain dry plant biomass; Immersion in an aqueous solution for leaching treatment, and then separating the supernatant to obtain a plant biomass leaching solution.

Specifically, when the plant biomass raw material is baked in a baking equipment, the baking temperature is 50°C to 70°C, and the baking time is more than 12 hours; the plant biomass dry material is immersed in an aqueous solution to soak When taking treatment, heating makes the aqueous solution boil for more than 1h.

Specifically, before processing the plant biomass raw material to obtain the plant biomass dry material or the plant biomass leaching solution, the method further includes: washing the plant biomass raw material with water, ethanol and acetone in sequence.

Specifically, the water-soluble copper salt is selected from one or more of copper nitrate, copper acetate, copper chloride, copper sulfate and basic copper carbonate.

Specifically, the concentration of the copper salt solution is 0.1-100 mg/mL.

Specifically, when the plant biomass dry material is selected to be added to the reaction kettle, the plant biomass is added in a ratio of 1:0.01-10 in which the mass ratio of the plant biomass dry material to the water-soluble copper salt is 1:0.01-10. dry material; when the plant biomass leaching solution is selected to be added to the reaction kettle, the plant biomass leaching solution and the water-soluble copper salt are added in a ratio of 1:0.1 to 100. Biomass Leachate.

Specifically, the temperature of the hydrothermal reaction is 120° C.˜300° C., and the time is 1 h˜96 h.

The preparation method of micro-nano copper sheet provided in the embodiment of the present invention uses plant biomass as a reducing agent component and a structure-directing agent to reduce water-soluble copper salt to obtain a copper sheet with a micro-nano size structure, and the preparation process is simple and the cost is low. . In the preparation process, no other chemical reagents (such as organic reagents, reducing agents, dispersants, structure-directing agents, etc.) are added except the precursor copper salt, which has the advantages of green and macro-scale preparation.

Description of drawings

Fig. 1 is the process flow diagram of the preparation method of the micro-nano copper sheet of the embodiment of the present invention;

Fig. 2 and Fig. 3 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 1 of the present invention;

Fig. 4 is the X-ray diffraction pattern of the micro-nano copper sheet prepared in Example 1 of the present invention;

Fig. 5 and Fig. 6 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 2 of the present invention;

7 and 8 are SEM images of the micro-nano copper sheets prepared in Example 3 of the present invention;

Fig. 9 and Fig. 10 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 4 of the present invention;

Figure 11 and Figure 12 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 5 of the present invention;

Figure 13 and Figure 14 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 6 of the present invention;

Figure 15 and Figure 16 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 7 of the present invention;

Figure 17 and Figure 18 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 8 of the present invention;

Figure 19 and Figure 20 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 9 of the present invention;

Figure 21 and Figure 22 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 10 of the present invention;

23 and 24 are scanning electron microscope images of the micro-nano copper sheet prepared in Example 11 of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described with reference to the drawings are merely exemplary and the invention is not limited to these embodiments.

An embodiment of the present invention provides a method for preparing a micro-nano copper sheet, as shown in FIG. 1 , the preparation method includes the steps:

S10, collecting and obtaining plant biomass raw materials, and drying the plant biomass raw materials to obtain plant biomass dry material or plant biomass leaching solution. Wherein, the plant biomass raw material is one or more of the roots, stems, branches, leaves, flowers, fruits and seeds of plants.

In a preferred solution, the plant biomass raw material is selected from the biomass raw material of evergreen trees. Described evergreen tree plants are, for example: Chinese pine, cedar, Korean pine, Huashan pine, sylvestris pine, masson pine, slash pine, oleifera, spruce, oriental orientalis, juniper, juniper, bamboo cypress, dragon cypress, Lohan pine, privet, coptis, magnolia, white orchid, Duying, acacia, banyan, camphor, laurel, sweet-scented osmanthus, longan, lychee and pipa, etc., can be selected from one or more kinds of evergreen arbor plant.

Specifically, the processing of the plant biomass raw material to obtain the plant biomass dry material includes: placing the plant biomass raw material in a roasting device for roasting to obtain the plant biomass dry material. Preferably, the baking temperature is 50°C to 70°C, and the baking time is more than 12h; in a more preferred technical solution, the baking time is 12h to 24h.

Specifically, the processing of the plant biomass raw material to obtain the plant biomass leaching solution includes: firstly preparing and obtaining the plant biomass dry material according to the above method for obtaining the plant biomass dry material; then preparing the plant biomass dry material; The dry material is immersed in an aqueous solution for leaching treatment, and then the supernatant is separated to obtain a plant biomass leaching solution. Preferably, the heating causes the aqueous solution to boil for more than 1 h. In a more preferred technical solution, heating makes the aqueous solution boil for 2h to 10h.

Specifically, before processing the plant biomass raw material to obtain the plant biomass dry material or the plant biomass leaching solution, the method further includes: washing the plant biomass raw material with water, ethanol and acetone in sequence.

S20, providing a water-soluble copper salt and dissolving it in water to obtain a copper salt solution.

Specifically, the water-soluble copper salt is selected from one or more of copper nitrate, copper acetate, copper chloride, copper sulfate and basic copper carbonate. In a preferred solution, the concentration of the copper salt solution is formulated in the range of 0.1-100 mg/mL.

S30, transferring the copper salt solution to a reaction kettle, and adding the plant biomass dry material or the plant biomass leaching solution to the reaction kettle. It should be noted that, when choosing to add the plant biomass leaching solution to the reactor, the plant biomass leaching solution and the copper salt solution may be mixed uniformly and then transferred to the reactor together.

Specifically, when the plant biomass dry material is selected to be added to the reaction kettle, the plant biomass is added in a ratio of 1:0.01-10 in which the mass ratio of the plant biomass dry material to the water-soluble copper salt is 1:0.01-10. Dry biomass material; when the plant biomass leaching solution is selected to be added to the reactor, the mass ratio of the plant biomass leaching solution to the water-soluble copper salt is 1:0.1 to 100. Add the plant biomass leachate.

S40, sealing the reaction kettle and performing a hydrothermal reaction, collecting the solid-liquid reaction product by solid-liquid separation, separating and removing by-products in the solid-state reaction product, and preparing the micro-nano copper sheet.

Specifically, the temperature of the hydrothermal reaction is 120° C.˜300° C., and the time is 1 h˜96 h. Among them, after the hydrothermal reaction is completed, solid-liquid separation is performed to collect the solid reaction product, and a centrifugal separation process is used to remove other by-products (such as two-dimensional nano-carbon, etc.) in the solid reaction product, and finally micro-nano copper sheets are obtained.

It should be noted that, in the above hydrothermal reaction: on the one hand, macromolecular components (cellulose, starch, etc.) contained in plant biomass are hydrolyzed into glucose as a reducing agent, and small molecular components (ketones, phenols, etc.) As structure-directing agents, the two work together to reduce water-soluble copper salts into elemental metal copper sheets with specific structures; on the other hand, copper salts catalyze carbonization of organic matter in plant biomass to obtain two-dimensional nanocarbons. The purpose of the present invention is to prepare and obtain micro-nano copper sheets, so the two-dimensional nano-carbon is separated and removed in the final product, and the micro-nano copper sheets are retained. By increasing the ratio of copper salt to plant biomass dry material or plant biomass leaching solution, the yield of micro-nano copper sheets can be increased. Therefore, in a preferred technical solution, the water-soluble copper salt and plant biomass dry matter in the reactor are mixed. The mass ratio of feed or plant biomass leachate is greater than 1.

The preparation method of the above-mentioned micro-nano copper sheet utilizes the macromolecular components (cellulose, starch, etc.) contained in the plant biomass to be hydrolyzed into glucose as a reducing agent, and the contained small molecular components (ketones, phenols, etc.) are used as a structural guide. The two work together to reduce the water-soluble copper salt to a specific structure of elemental metal copper sheets. In the preparation process, no other chemical reagents (such as organic reagents, reducing agents, dispersing agents, structural Directing agent, etc.), has the advantages of simple process, low cost, green macro and so on. According to the preparation method of the micro-nano copper sheet as described above, the thickness of the micro-nano copper sheet obtained by the preparation is in the range of 5 nm to 5 μm, and the radial dimension is in the range of 30 nm to 50 mm.

It should be noted that the micro-nano copper sheet described in the embodiments of the present invention refers to a micro-nano copper sheet having a thickness of the order of nanometers or the order of micrometers.

Example 1

The leaves of Pinus tabulaeformis were collected, washed sequentially with water, ethanol and acetone, and dried in an oven at 60° C. for 12 hours to obtain the dried leaves of Pinus tabulaeformis as dry plant biomass.

4 mg of copper nitrate was weighed, dissolved in 40 mL of water, fully stirred to dissolve completely, and the obtained copper salt solution was a copper nitrate solution.

The above-mentioned copper nitrate solution was transferred to the reaction kettle, and 4 mg of dried Chinese pine leaves were added.

The above reaction kettle was sealed, placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set to 120°C, and the reaction time was 1 hour.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 2 and FIG. 3 are SEM images of the micro-nano copper sheet prepared in this embodiment, and FIG. 4 is an XRD diagram of the micro-nano copper sheet prepared in this embodiment.

Example 2

The branches of L. japonicus were collected, washed with water, ethanol and acetone in sequence, and dried in an oven at 65° C. for 14 hours to obtain the dried L. japonicus branches as the dry plant biomass.

Weigh 150 mg of copper nitrate, dissolve it in 150 mL of water, stir well to dissolve it completely, and the obtained copper salt solution is a copper nitrate solution.

The above-mentioned copper nitrate solution was transferred to the reaction kettle, and 15 mg of dried Lonba cypress branches were added.

The above reaction kettle was sealed, placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set to 160°C, and the reaction time was 3 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

5 and 6 are SEM images of the micro-nano copper sheets prepared in this example.

Example 3

The leaves of Magnolia grandiflora were collected, washed with water, ethanol and acetone in sequence, and dried in an oven at 50° C. for 16 hours to obtain the dried leaves of Magnolia grandiflora as dry plant biomass.

Weigh 400 mg of copper acetate, dissolve it in 300 mL of water, stir well to dissolve it completely, and the obtained copper salt solution is a copper acetate solution.

The above copper acetate solution was transferred to the reaction kettle, and 200 mg of dried Magnolia japonica leaves were added.

The above reaction kettle was sealed, placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set to 180°C, and the reaction time was 8 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 7 and FIG. 8 are SEM images of the micro-nano copper sheets prepared in this example.

Example 4

The roots of banyan trees were collected, washed with water, ethanol and acetone in sequence, and dried in an oven at 60° C. for 18 hours to obtain dried banyan tree roots as dry plant biomass.

Weigh 500 mg of basic copper carbonate, dissolve it in 400 mL of water, fully stir to dissolve it completely, and the obtained copper salt solution is a basic copper carbonate solution.

The above basic copper carbonate solution was transferred to the reaction kettle, and 300 mg of dried banyan tree roots were added.

The above reaction kettle was sealed, placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set at 200°C, and the reaction time was 10 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 9 and FIG. 10 are SEM images of the micro-nano copper sheets prepared in this example.

Example 5

The camphor leaves were collected, washed with water, ethanol and acetone in sequence, and dried in an oven at 70° C. for 18 hours to obtain dried camphor leaves as dry plant biomass.

Weigh 600 mg of copper acetate, dissolve it in 600 mL of water, fully stir to dissolve it completely, and the obtained copper salt solution is a copper acetate solution.

The above copper acetate solution was transferred to the reaction kettle, and 500 mg of dried camphor leaves were added.

The above reaction kettle was sealed, placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set at 200°C, and the reaction time was 24 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 11 and FIG. 12 are SEM images of the micro-nano copper sheets prepared in this example.

Example 6

Osmanthus fragrans branches were collected, washed sequentially with water, ethanol and acetone, and dried in an oven at 70° C. for 20 hours to obtain dried osmanthus fragrans branches as plant biomass dry material.

Weigh 2 g of cupric chloride, dissolve it in 3 L of water, fully stir to dissolve it completely, and the obtained copper salt solution is a cupric chloride solution.

The above-mentioned cupric chloride solution was transferred to the reaction kettle, and 8 g of dried osmanthus fragrans branches were added.

The above reaction kettle was sealed, placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set at 250°C, and the reaction time was 48 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 13 and FIG. 14 are SEM images of the micro-nano copper sheets prepared in this example.

Example 7

The longan roots were collected, washed with water, ethanol and acetone in sequence, and dried in an oven at 60° C. for 22 hours to obtain dried longan roots as dry plant biomass.

Weigh 4 g of copper chloride, dissolve it in 4 L of water, fully stir to dissolve it completely, and the obtained copper salt solution is a copper chloride solution.

The above-mentioned cupric chloride solution was transferred to the reaction kettle, and 3 g of dried longan roots were added.

The above reaction kettle was sealed, placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set to 250°C, and the reaction time was 96 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 15 and FIG. 16 are SEM images of the micro-nano copper sheets prepared in this example.

Example 8

The litchi stems were collected, washed with water, ethanol and acetone in sequence, and dried in an oven at 50° C. for 24 hours to obtain the dried litchi stems as dry plant biomass.

Weigh 4 g of copper sulfate, dissolve it in 6 L of water, fully stir to dissolve it completely, and the obtained copper salt solution is a copper sulfate solution.

The above-mentioned copper sulfate solution was transferred to the reactor, and 20 g of dry litchi stems were added.

The above-mentioned reaction kettle was sealed, placed in a hydrothermal oven to carry out hydrothermal reaction, the reaction temperature was set to 300 ° C, and the reaction time was 48 hours

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 17 and FIG. 18 are SEM images of the micro-nano copper sheets prepared in this example.

Example 9

The stems of Magnolia grandiflora were collected, washed with water, ethanol and acetone in sequence, and then placed in an oven at 65° C. for drying for 14 hours to obtain dried stems of Magnolia grandiflora as plant biomass dry material.

Weigh 20 mg of dried Magnolia grandiflora stems in 200 mL of water, heat and boil for 2 h, and centrifuge the supernatant to collect the plant biomass leaching solution.

Weigh 200 mg of copper nitrate, dissolve it in 200 mL of water, fully stir to dissolve it completely, and the obtained copper salt solution is a copper nitrate solution.

The above-mentioned copper nitrate solution and the plant biomass leaching solution were mixed evenly, transferred to a reactor of suitable size, sealed and placed in a hydrothermal oven for hydrothermal reaction, with a reaction temperature of 160° C. and a reaction time of 3 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 19 and FIG. 20 are SEM images of the micro-nano copper sheets prepared in this example.

Example 10

The leaves of Pistacia chinensis were collected, washed with water, ethanol and acetone in sequence, and then placed in an oven at 65° C. for drying for 18 hours to obtain dried Pistacia chinensis leaves as dry plant biomass.

Weigh 200 mg of dried Pistacia chinensis leaves into 300 mL of water, heat and boil for 5 hours, and centrifuge the supernatant to collect the plant biomass extract.

Weigh 2 g of copper sulfate, dissolve it in 300 mL of water, fully stir to dissolve it completely, and the obtained copper salt solution is a copper sulfate solution.

The above-mentioned copper sulfate solution and the plant biomass leaching solution were mixed evenly, transferred to a reactor of suitable size, sealed and placed in a hydrothermal oven for hydrothermal reaction, with a reaction temperature of 180° C. and a reaction time of 5 hours.

After the reaction is completed and naturally cooled, solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 21 and FIG. 22 are SEM images of the micro-nano copper sheets prepared in this example.

Example 11

The roots of osmanthus fragrans were collected, washed with water, ethanol and acetone in sequence, and then dried in an oven at 70° C. for 20 hours to obtain dried osmanthus roots as plant biomass dry material.

Weigh 3 g of dried osmanthus root in 500 mL of water, heat and boil for 10 h, and centrifuge the supernatant to collect the plant biomass leaching solution.

5 g of copper chloride was weighed, dissolved in 500 mL of water, fully stirred to dissolve completely, and the obtained copper salt solution was a copper chloride solution.

The above-mentioned cupric chloride solution and the plant biomass leaching solution were mixed evenly, and transferred to a reactor of suitable size, sealed and placed in a hydrothermal oven for hydrothermal reaction, the reaction temperature was set to 200 ° C, and the reaction time was 12 hours .

After the reaction is finished and naturally cooled, the solid-liquid separation is performed to collect the solid-state reaction product, and a centrifugal separation process is used to remove other by-products in the solid-state reaction product to obtain micro-nano copper sheets.

FIG. 23 and FIG. 24 are SEM images of the micro-nano copper sheets prepared in this example.

To sum up, the preparation method of the micro-nano copper sheet provided by the present invention has many advantages such as simple process, low cost, environmental friendliness and the like.

The above are only specific embodiments of the present application. It should be pointed out that for those skilled in the art, without departing from the principles of the present application, several improvements and modifications can also be made. It should be regarded as the protection scope of this application.

Claims (10)

1. A method for preparing a micro-nano copper sheet is characterized by comprising the following steps:

collecting and obtaining a plant biomass raw material, and processing the plant biomass raw material to obtain a plant biomass dry material or a plant biomass leaching solution;

providing a water-soluble copper salt and dissolving the water-soluble copper salt in water to obtain a copper salt solution;

transferring the copper salt solution to a reaction kettle, and adding the plant biomass dry material or the plant biomass leaching solution into the reaction kettle;

and sealing the reaction kettle, then carrying out hydrothermal reaction, carrying out solid-liquid separation, collecting a solid reaction product, and separating to remove a byproduct in the solid reaction product to prepare the micro-nano copper sheet.

2. The method for preparing the micro-nano copper sheet according to claim 1, wherein the plant biomass raw material is one or more than two of roots, stems, branches, leaves, flowers, fruits and seeds of plants.

3. The method for preparing the micro-nano copper sheet according to claim 2, wherein the plant biomass raw material is selected from biomass raw materials of evergreen arbor plants.

4. The method for preparing the micro-nano copper sheet according to any one of claims 1 to 3, which is characterized in that,

the processing of the plant biomass raw material to obtain the plant biomass dry material comprises the following steps: placing the plant biomass raw material into baking equipment for baking to obtain a plant biomass dry material;

the processing of the plant biomass feedstock to obtain a plant biomass leachate comprises: placing the plant biomass raw material into baking equipment for baking to obtain a plant biomass dry material; and soaking the plant biomass dry material in an aqueous solution for leaching treatment, and then separating out supernatant to obtain plant biomass leaching solution.

5. The method for preparing the micro-nano copper sheet according to claim 4, wherein,

when the plant biomass raw material is placed in baking equipment for baking, the baking temperature is 50-70 ℃, and the baking time is more than 12 hours;

when the plant biomass dry material is soaked in the aqueous solution for leaching treatment, the aqueous solution is boiled for more than 1h by heating.

6. The method for preparing the micro-nano copper sheet according to claim 4, wherein before the plant biomass raw material is processed to obtain the plant biomass dry material or the plant biomass leaching solution, the method further comprises the following steps: washing the plant biomass raw material by using water, ethanol and acetone in sequence.

7. The method for preparing the micro-nano copper sheet according to claim 1, wherein the water-soluble copper salt is one or more than two selected from copper nitrate, copper acetate, copper chloride, copper sulfate and basic copper carbonate.

8. The method for preparing the micro-nano copper sheet according to claim 7, wherein the concentration of the copper salt solution is 0.1-100 mg/mL.

9. The method for preparing the micro-nano copper sheet according to any one of claims 1, 7 or 8, which is characterized in that,

when the plant biomass dry material is selected to be added into the reaction kettle, adding the plant biomass dry material according to the mass ratio of the plant biomass dry material to the water-soluble copper salt of 1: 0.01-10;

and when the plant biomass leaching solution is selectively added into the reaction kettle, adding the plant biomass leaching solution according to the mass ratio of the plant biomass leaching solution to the water-soluble copper salt of 1: 0.1-100.

10. The method for preparing the micro-nano copper sheet according to claim 1, wherein the temperature of the hydrothermal reaction is 120-300 ℃ and the time is 1-96 h.

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