A method for laser-induced preparation of copper oxide nanoparticle in-situ composite graphene material and application

Abstract

The application provides a method for preparing a graphene material in situ combined with copper oxide nanoparticles by laser induction and application thereof. First, a copper acetate solution is used to infiltrate softwood shallow cell wall tissue, and then ascorbic acid is used to reduce the softwood in situ, and small-size copper particles are uniformly embedded in the softwood after low-temperature vacuum drying, so that the uniformity and simplicity of modification are realized. Laser irradiation of the copper-containing softwood can prepare chain-bead-shaped graphene / copper oxide composite nanomaterials. The material itself has a three-dimensional wire mesh structure and has rich field emission tips; in addition, the heterojunction formed in situ by the copper oxide particles and the graphene has excellent electron transport characteristics, so that the copper oxide serves as an emission site and further improves the field emission performance.

Description

A method for laser-induced in-situ preparation of copper oxide nanoparticles composite graphene materials and their application Technical Field

[0001] This invention specifically relates to a method for laser-induced in-situ preparation of copper oxide nanoparticles composite graphene materials, which can be applied to optoelectronic devices and other related fields. Background Technology

[0002] Copper oxide nanoparticle-modified graphene composite nanomaterials possess advantages such as environmental friendliness and low work function, making them highly valuable in the field of vacuum electron field emission (FEE). However, the high cost of graphene materials prepared by chemical vapor deposition, hydrothermal, or solvothermal methods, and the complex fabrication processes of copper oxide@graphene heterostructures, limit their widespread application. Existing hydrothermal or solvothermal preparation processes are cumbersome and complex, making it difficult to achieve green and environmentally friendly synthesis; furthermore, they cannot achieve one-step patterned fabrication of in-situ copper oxide particles coated with graphene. Therefore, this invention proposes a green, simple, and low-cost laser-induced in-situ method using copper salt-containing cork to prepare copper oxide nanoparticle-modified graphene nanocomposite nanomaterials. Summary of the Invention

[0003] Based on this, the present invention proposes a low-cost and simple method for preparing a composite material of in-situ modified graphene heterostructure by laser-induced synthesis of copper oxide nanoparticles. The advantages of this preparation method are: (1) laser-induced copper salt-containing cork can synthesize copper oxide nanoparticles coated with graphene in a green, low-cost, one-step process; (2) the density of the coated copper oxide particles in the copper oxide@graphene composite material structure is controllable; (3) patterned preparation of copper oxide-coated graphene composite materials can be achieved; (4) the formed copper oxide@graphene heterostructure can effectively reduce the work function of the material and improve its electron field emission capability.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for laser-induced in-situ preparation of copper oxide nanoparticles composite graphene materials includes the following steps:

[0006] (1) Slice the cork along the transverse grain, sonicate it in anhydrous ethanol and pure water respectively, and then vacuum dry it;

[0007] (2) The dried cork is soaked in copper acetate solution for a certain period of time. Because the density of cork is less than that of water, it floats on the surface. The copper acetate solution is then used to penetrate the shallow tissue at the bottom of the cork by utilizing the capillary effect of the solution.

[0008] (3) The cork soaked in copper acetate was placed in ascorbic acid solution and soaked again for a certain period of time to complete the in-situ reduction of copper ions in the cork tissue. Finally, the sample was dried in an oven at a constant temperature.

[0009] (4) The copper-containing cork prepared in step (3) was irradiated with laser to synthesize a copper oxide-modified graphene composite material.

[0010] Preferably, the concentration of the copper acetate solution in step (2) is 25-100 mM.

[0011] Preferably, the concentration of the ascorbic acid solution in step (3) is 25-100 mM.

[0012] Preferred, the drying in steps (1) and (3) specifically refers to drying at 60°C for 48 hours.

[0013] Preferred, the soaking time in steps (2) and (3) is 24 hours.

[0014] Preferred irradiation parameters in step (4): laser power 100mW, scanning speed 0.4mm / s, laser scanning spacing 100μm.

[0015] Application: In-situ modified copper oxide graphene composite material as an electrode material.

[0016] The main technical problem to be solved by this invention is:

[0017] (1) A one-step laser-induced synthesis of copper oxide nanoparticles to in-situ coat graphene composite material and form copper oxide nanoparticle@graphene heterostructure with excellent electron transport.

[0018] (2) Achieve uniform distribution of copper oxide nanoparticles in graphene materials and controllable density of coated nanoparticles;

[0019] (3) A graphene composite material coated with copper oxide nanoparticles forming a 3D structure;

[0020] (4) Achieve one-step preparation of graphene composite material coated with copper oxide nanoparticles.

[0021] The key point of this invention is:

[0022] (1) In the synthesis scheme, cork impregnated with copper acetate is placed in ascorbic acid solution and reduced in situ to small copper particles. The reduced copper particles are uniformly embedded in situ in the cork cell wall tissue.

[0023] (2) Laser-induced irradiation of cork embedded with copper particles at room temperature can yield a graphene composite material coated with copper oxide nanoparticles in one step.

[0024] (3) The concentration of the copper acetate solution used to impregnate the cork is adjustable, so the density of copper oxide nanoparticles in the laser-synthesized copper oxide@graphene composite material is controllable.

[0025] (4) By adjusting the patterning of cork, a green, low-cost, and simple one-step patterning method for rapid preparation of copper oxide nanoparticle composite graphene nanomaterials can be achieved.

[0026] The advantages of this invention are:

[0027] In the synthesis method of copper oxide@graphene composite material, the superficial cell wall tissue of cork is first impregnated with copper acetate solution, followed by in-situ reduction with ascorbic acid and low-temperature vacuum drying to form small-sized copper particles uniformly embedded in the cork, achieving uniformity and simplicity of modification. Laser irradiation of copper-containing cork can controllably prepare bead-like graphene / copper oxide composite nanomaterials. This material itself has a three-dimensional linear network structure with abundant field emission tips; furthermore, the heterojunction formed in situ by copper oxide particles and graphene has excellent electron transport properties, allowing copper oxide to act as emission sites, further improving field emission performance.

[0028] It has the following advantages:

[0029] (1) The substrate used is biomass material, which has the advantages of wide availability and green environmental protection.

[0030] (2) After being soaked in copper acetate solution, the cork was reduced in situ with ascorbic acid to achieve uniform embedding of copper particles in the cork tissue.

[0031] (3) The concentration of the copper acetate solution used to impregnate the cork is adjustable, so the density of copper oxide nanoparticles in the laser-synthesized copper oxide@graphene composite material is controllable.

[0032] (4) Patterned customization of copper oxide@graphene composite materials can be achieved.

[0033] (5) The in-situ synthesized copper oxide@graphene heterojunction composite material has excellent electron transport characteristics and rich sharp edge morphology, which can effectively reduce the turn-on and threshold electric fields and improve the electron emission characteristics of the material. Attached Figure Description

[0034] Figure 1 shows FESEM images of the products of different embodiments: (a) electron microscope image of pure graphene, (b) electron microscope image of the comparative example, (c) electron microscope image of Example 1, (d) electron microscope image of Example 2, (e) electron microscope image of Example 3, (f) EDS elemental distribution map of Example 2.

[0035] Figure 2 shows the (a) TEM, (b) HRTEM and (c) Raman spectra of the product of Example 2;

[0036] Figure 3 shows the XPS spectra of the product of Example 2: (a) overall spectrum, (b) C1s spectrum, (c) O 1s spectrum, (d) Cu 2p spectrum;

[0037] Figure 4 shows the field emission characteristics of the embodiment: (a) JE curve, (b) FN curve, (c) IT stability curve. Detailed Implementation

[0038] To make the above-mentioned features and advantages of the present invention more apparent and understandable, specific embodiments are described below in detail. Unless otherwise specified, the methods of the present invention are conventional methods in the art.

[0039] Example 1

[0040] The cork was sliced ​​along the transverse grain to obtain 10×6×2 mm pieces. 3 The samples were sonicated in anhydrous ethanol and pure water for 15 min each, and then vacuum dried at 60℃ for 48 h. The dried cork was then immersed in a pre-prepared copper acetate solution (25 mM, 50 mL) for 24 h. Because cork is less dense than water, it floats on the surface, and the solution penetrates into the shallow tissue at the bottom of the cork using capillary action. The copper acetate-impregnated cork was then immersed again in a 25 mM, 50 mL ascorbic acid solution for 24 h to complete the in-situ reduction of copper ions within the cork tissue. Finally, the samples were dried in an oven at 60℃ for 48 h.

[0041] The copper-containing cork prepared above was irradiated with laser (irradiation parameters: laser power 100mW, scanning speed 0.4mm / s, laser scanning spacing 100um) to synthesize a copper oxide in-situ modified graphene composite material.

[0042] Example 2

[0043] The cork was sliced ​​along the transverse grain to obtain 10×6×2 mm pieces. 3 The samples were sonicated in anhydrous ethanol and pure water for 15 min each, and then vacuum dried at 60℃ for 48 h. The dried cork was then immersed in a pre-prepared copper acetate solution (50 mM, 50 mL) for 24 h. Because cork is less dense than water, it floats on the surface, and the solution penetrates into the shallow tissue at the bottom of the cork using capillary action. The copper acetate-impregnated cork was then immersed again in a 50 mM, 50 mL ascorbic acid solution for 24 h to complete the in-situ reduction of copper ions within the cork tissue. Finally, the samples were dried in an oven at 60℃ for 48 h.

[0044] The copper-containing cork prepared above was irradiated with laser (irradiation parameters: laser power 100mW, scanning speed 0.4mm / s, laser scanning spacing 100um) to synthesize a copper oxide in-situ modified graphene composite material.

[0045] Example 3

[0046] The cork was sliced ​​along the transverse grain to obtain 10×6×2 mm pieces.3 The samples were sonicated in anhydrous ethanol and pure water for 15 min each, and then vacuum dried at 60℃ for 48 h. Subsequently, the dried cork was immersed in a pre-prepared copper acetate solution (100 mM, 50 mL) for 24 h. Because the cork is less dense than water, it floats on the surface, and the solution penetrates into the shallow tissue at the bottom of the cork using capillary action. The copper acetate-impregnated cork was then immersed again in a 100 mM, 50 mL ascorbic acid solution for 24 h to complete the in-situ reduction of copper ions within the cork tissue. Finally, the samples were dried in an oven at 60℃ for 48 h.

[0047] The copper-containing cork prepared above was irradiated with laser (irradiation parameters: laser power 100mW, scanning speed 0.4mm / s, laser scanning spacing 100um) to synthesize a copper oxide in-situ modified graphene composite material.

[0048] To compare the results, we prepared pure graphene materials by direct laser irradiation of copper-free cork under the same parameters. We also prepared a comparative sample containing only copper acetate, without Vc reduction, under the same parameters.

[0049] Comparative Example (Synthesis process similar to Example 2, but without the introduction of ascorbic acid reagent to participate in the reaction)

[0050] The cork was sliced ​​along the transverse grain to obtain 10×6×2 mm pieces. 3 The samples were sonicated in anhydrous ethanol and pure water for 15 min each, and then vacuum dried at 60℃ for 48 h. Subsequently, the dried cork was immersed in a pre-prepared copper acetate solution (50 mM, 50 mL) for 24 h. Because the cork is less dense than water, it floated on the surface, and the solution penetrated into the shallow tissue at the bottom of the cork using capillary action. The samples were then removed and finally dried in an oven at 60℃ for 48 h.

[0051] The copper-containing cork prepared above was irradiated with laser (irradiation parameters: laser power 100mW, scanning speed 0.4mm / s, laser scanning spacing 100um) to synthesize a copper oxide in-situ modified graphene composite material.

[0052] Field launch performance test:

[0053] Using diode construction at a vacuum pressure of 10 -5 Field emission performance of the samples was tested at room temperature. The laser-bombarded synthesized sample served as the field emission cathode, and a pure copper anode with a tip diameter of 1.0 mm was used as the electron receiving anode. The electrode gap could be adjusted using a micrometer; in this study, the anode-cathode distance was fixed at 550 μm. A computer-controlled automatic data acquisition system (Keithely 2290-6485) was used to record the current-voltage (IV) and current-time (IT) characteristics.

[0054] Figures 1-3 show the morphology and microstructure characterization of the product:

[0055] Figure 1 shows FESEM images of the products from different embodiments: (a) electron microscope image of pure graphene, (b) electron microscope image of comparative example, (c) electron microscope image of Example 1, (d) electron microscope image of Example 2, (e) electron microscope image of Example 3, (f) EDS elemental distribution map of Example 2.

[0056] As shown in Figure 1, with increasing copper content (0, 25, 50, 100 mM), the morphology of the synthesized graphene changed from the flocculent structure of Example 1 to the beaded structure of Example 2, and then to the blocky structure of Example 3. Higher copper content resulted in a thicker induced etching structure. The comparative example, synthesized without ascorbic acid, shows fewer sharp-edge structures on the surface. Ascorbic acid is a good reducing agent and can react with copper acetate under certain conditions to generate copper nanoparticles. In the comparative experiment, without ascorbic acid, when cork adsorbed with copper acetate was irradiated with laser, the copper acetate decomposed and the cork carbonized. During this process, the copper acetate decomposed and absorbed laser energy, which is the reason for the reduction in sharp-edge structures in the product. The sharp-edge morphology of the product helps to increase the field enhancement factor, thereby correspondingly reducing the electron emission onset and threshold electric field strength.

[0057] Figure 2 shows the (a) TEM, (b) HRTEM and (c) Raman spectra of the product of Example 2.

[0058] TEM revealed that copper oxide nanoparticles were in situ coated on graphene. High-magnification transmission electron microscopy (HRTEM) showed that the lattice spacing of 3.37 Å corresponded to the (111) crystal plane of copper oxide; while the copper oxide particles were in situ coated with graphene with a lattice spacing of 3.43 Å (002 crystal plane).

[0059] Raman spectra show: A g (289.5nm), B g (351nm), and 2B g The peak at 627 nm is the Raman vibration peak of CuO. The D peak (≈1353 cm⁻¹) is also present. -1 sp belongs to disordered carbon and atomic lattice defects 3 Hybridization, G peak (≈1591 cm⁻¹) -1 ) corresponds to the sp structure of ordered carbon and graphene 2 Hybridization.

[0060] Figure 3 shows the XPS spectra of the product of Example 2: (a) overall spectrum, (b) C1s spectrum, (c) O 1s spectrum, (d) Cu 2p spectrum.

[0061] Showing the chemical bonds of carbon in sp2 and sp 3 Predominantly present, with a small amount of carbon-oxygen bonds; Cu mainly consists of 2p orbitals. 2+ It exists in the form of.

[0062] Figure 4 shows the field emission characteristics of the embodiment: (a) JE curve, (b) FN curve, (c) IT stability curve.

[0063] The JE plot in Figure 4a shows that the threshold electric field strength of the product is 1 mA / cm. 2 The electric field strength required for the current density is as follows: 2.11 V / µm for laser-induced pure graphene; 2.43 V / µm for the comparative example; 1.95 V / µm for Example 1; 1.57 V / µm for Example 2; and 2.14 V / µm for Example 3.

[0064] The FN plot in Figure 4b shows that the slopes of pure graphene, the comparative example, and the products of Examples 1, 2, and 3 are -8.82, -8.76, -7.50, -7.80, and -12.27, respectively. The gentler the slope, the greater the field enhancement factor.

[0065] Figure 4c shows the stability of field emission performance. It can be observed that, compared with pure graphene, the copper oxide particle-modified graphene cathode material still exhibits stable electron emission characteristics under high field emission current conditions.

[0066] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for laser-induced in-situ preparation of copper oxide nanoparticles composite graphene materials, characterized in that, The process includes the following steps: (1) Slicing the cork along the transverse grain, ultrasonically treating it in anhydrous ethanol and pure water respectively, and vacuum drying it; (2) Soaking the dried cork in copper acetate solution for a certain period of time. Because the cork is less dense than water, it floats on the surface. By utilizing the capillary effect of the solution, the copper acetate solution is allowed to penetrate into the shallow tissue at the bottom of the cork; (3) Soaking the cork soaked in copper acetate solution in ascorbic acid solution for a certain period of time again to complete the in-situ reduction of copper ions in the cork tissue. Finally, the sample is dried at a constant temperature in an oven; (4) The copper-containing cork prepared in step (3) is irradiated with laser to synthesize copper oxide nanoparticles in-situ composite graphene material.

2. The method according to claim 1, characterized in that, The concentration of copper acetate solution is 25-100 mM.

3. The method according to claim 1, characterized in that, The concentration of ascorbic acid solution is 25-100 mM.

4. The method according to claim 1, characterized in that, The drying in steps (1) and (3) specifically refers to drying at 60℃ for 48 hours.

5. The method according to claim 1, characterized in that, The soaking time in steps (2) and (3) is 24 hours.

6. The method according to claim 1, characterized in that, The irradiation parameters in step (4) are: laser power 100mW, scanning speed 0.4mm / s, and laser scanning spacing 100μm.

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