Modified graphene oxide, method for preparing the same, and use thereof

Abstract

The application discloses modified graphene oxide and a preparation method and application thereof. The modified graphene oxide is obtained by the reaction of beta-diketone rare earth supermolecule and graphene oxide; wherein the ratio of the amount of substance of the rare earth element in the beta-diketone rare earth supermolecule to the mass of the graphene oxide is 0.08-0.15 mmol:0.05 g. The modified graphene oxide has good dispersibility.

Description

Technical Field

[0001] This invention relates to a modified graphene oxide, its preparation method, and its applications. Background Technology

[0002] Graphene oxide, an oxide of graphene, possesses a single atomic layer and can extend laterally to tens of micrometers, its structure spanning the typical scales of general chemistry and materials science. It is produced by introducing active oxygen-containing groups into graphene, resulting in modified graphene sheets. This increases the number of active reaction sites, allowing for improvements in the properties of graphene oxide through various reactions with oxygen-containing functional groups. Furthermore, graphene oxide is considered a novel, high-performance, non-traditional soft carbon material with a high specific surface area and abundant surface functional groups. Graphene oxide composites include polymer-based and inorganic-based composites. Due to its wide range of applications, surface modification of graphene oxide has become a key research focus.

[0003] However, due to the large specific surface area of ​​graphene oxide, the interaction between the layers is increased, making it prone to agglomeration. Furthermore, these agglomerates are difficult to separate, which greatly reduces the performance of graphene oxide and consequently affects the performance improvement and application of graphene oxide composites. To obtain high-performance graphene oxide composites and expand the application range of graphene oxide, it is necessary to improve the dispersibility of graphene oxide in matrices such as organic solvents and polymers.

[0004] CN107170586A discloses a metal-coordinated supramolecular mesh and three-dimensional graphene bulk composite material, its preparation method, and its application. The preparation method includes: (1) ultrasonically dispersing graphene oxide in H2O-DMF solution for a period of time; (2) adding a metal ion precursor to the solution obtained in step (1), continuing ultrasonication for a period of time, adding a ligand, and continuing ultrasonication for a period of time, wherein the molar ratio of the metal ion precursor to the ligand is determined by the chemical formula of the target product; (3) reacting the solution obtained in step (2) at 160-200℃ to obtain a coordination supramolecular mesh-three-dimensional graphene gel composite material; (4) soaking the gel composite material obtained in step (3) in ethanol and water; (5) drying to obtain a metal-coordinated supramolecular mesh and three-dimensional graphene bulk composite material. This bulk composite material can be used to prepare supercapacitor electrodes, but its reaction temperature is relatively high.

[0005] CN108147393A discloses a high-strength, high-toughness, and high-conductivity graphene film and its preparation method. The preparation method includes: mixing a small amount of rare earth metal ions, polymers, and graphene oxide to form a uniform hydrosol; casting and air-drying to form a film; and then successively undergoing reduction, washing, and drying steps to obtain the graphene film. This graphene film exhibits good strength, toughness, and conductivity. The patent document describes the formation of a graphene film.

[0006] CN108878843A discloses a method for modifying graphene and its application in lithium battery composite materials. The modified graphene is obtained by modifying graphene oxide with a modifier composed of octaphenylsilsesquioxane, disodium nonylphenol polyoxyethylene ether sulfosuccinate, and a rare earth coupling agent. The graphene modified in this patent document can improve its dispersibility and compatibility, but the modifier uses a variety of raw materials. Summary of the Invention

[0007] One object of this invention is to provide a modified graphene oxide with good dispersibility. Compared with unmodified graphene oxide, the dispersibility is significantly improved, making it suitable for preparing battery electrodes and improving conductivity. Another object of this invention is to provide a method for preparing the modified graphene oxide as described above. Yet another object of this invention is to provide applications of the modified graphene oxide as described above. The above objects are achieved by the following technical solutions.

[0008] On one hand, the present invention provides a modified graphene oxide, which is obtained by reacting β-diketone rare earth supramolecular elements with graphene oxide; wherein the mass ratio of the rare earth element in the β-diketone rare earth supramolecular elements to the mass of graphene oxide is 0.08-0.15 mmol:0.05 g.

[0009] In the modified graphene oxide of the present invention, preferably, the β-diketone ligand in the β-diketone rare earth supramolecular is benzoyltrifluoroacetone.

[0010] In the modified graphene oxide of the present invention, preferably, the rare earth element in the β-diketone rare earth supramolecular is selected from one of Eu, La, Sm and Gd.

[0011] On the other hand, the present invention also provides a method for preparing the modified graphene oxide as described above, comprising the following steps:

[0012] An alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules was mixed with graphene oxide powder and reacted at 75–100 °C. After the reaction was completed, the temperature was lowered, the solid and liquid were separated, and the separated solid was washed and dried to obtain the modified graphene oxide.

[0013] The ratio of the amount of rare earth elements in the β-diketone rare earth supramolecular to the mass of graphene oxide is 0.08–0.15 mmol:0.05 g.

[0014] According to the preparation method of the present invention, preferably, the alcohol-containing aqueous solution of the β-diketone rare earth supramolecular is prepared by the following steps:

[0015] A β-diketone ligand, a basic reagent, and an alcohol solution are mixed to obtain a ligand solution; the ligand solution is then mixed with an aqueous solution of a rare earth salt and reacted to obtain an alcohol-containing aqueous solution of the β-diketone rare earth supramolecular.

[0016] According to the preparation method of the present invention, preferably, the β-diketone ligand is benzoyltrifluoroacetone; the alkaline reagent is selected from at least one of triethylamine and pyridine; and the rare earth salt is a rare earth chloride.

[0017] According to the preparation method of the present invention, preferably, the molar ratio of β-diketone ligand, basic reagent and rare earth salt is 3-4:4-5:1.

[0018] According to the preparation method of the present invention, preferably, the alcohol solution is a solution formed by C1-C3 alcohol and water, wherein the volume ratio of C1-C3 alcohol to water is 1:8 to 12.

[0019] The preparation method according to the present invention preferably includes the following specific steps:

[0020] An alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules was mixed with graphene oxide powder and reacted at 75–100 °C for 4–8 h. After the reaction was completed, the temperature was lowered, and the solid and liquid were separated. The separated solid was washed with C1-C3 alcohol and then dried to obtain the modified graphene oxide.

[0021] In another aspect, the present invention also provides the application of the modified graphene oxide as described above in the preparation of battery electrodes.

[0022] The graphene oxide of this invention can reduce the interfacial and surface energy of graphene oxide, improve its dispersibility, and enhance its conductivity. The preparation method of this invention does not damage the structure of graphene oxide itself, maximizing the excellent properties of graphene. The preparation method of this invention involves preparing a modified liquid (i.e., an alcoholic aqueous solution containing rare earth supramolecular weights) by coordination-driven self-assembly of rare earth salts and benzoyltrifluoroacetone. Under heating conditions, this modified liquid allows the rare earth supramolecular weights to coordinate with the oxygen-containing functional groups of graphene oxide, thereby adsorbing as stabilizers onto the graphene surface. This results in graphene sheets with strong negative charge, enhanced dispersibility, and reduced agglomeration. Attached Figure Description

[0023] Figure 1 The images are SEM images of the graphene oxide in Example 1 before and after modification, at different magnifications.

[0024] Figure 2 This is a cyclic voltammogram of the modified graphene oxide from Example 1.

[0025] Figure 3 The image shows the fluorescence spectrum of the modified graphene oxide from Example 1.

[0026] Figure 4 The images shown are SEM images of the graphene oxide before and after modification in Example 2, at different magnifications. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0028] <Modified graphene oxide>

[0029] The modified graphene oxide of this invention is obtained by reacting β-diketone rare earth supramolecular molecules with graphene oxide. This is beneficial for improving the dispersibility of graphene oxide.

[0030] The β-diketone ligand in the β-diketone rare earth supramolecular is preferably benzoyltrifluoroacetone. The rare earth element in the β-diketone rare earth supramolecular is selected from Eu, La, Sm and Gd, preferably from Eu and La.

[0031] The mass ratio of rare earth elements in the β-diketone rare earth supramolecular to the mass of graphene oxide is 0.08–0.15 mmol:0.05 g, preferably 0.09–0.12 mmol:0.05 g, and more preferably 0.1–0.11 mmol:0.05 g.

[0032] <Preparation Method>

[0033] The preparation method of the present invention includes the following steps: (1) the preparation step of an alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules; (2) the preparation step of modified graphene oxide. These are described in detail below.

[0034] Preparation steps of alcohol-containing aqueous solutions of β-diketone rare earth supramolecular molecules

[0035] A β-diketone ligand, a basic reagent, and an alcohol solution are mixed to obtain a ligand solution. This ligand solution is then mixed with an aqueous solution of a rare earth salt and reacted to obtain an alcohol-containing aqueous solution of the β-diketone rare earth supramolecular weight. This process is beneficial for modifying graphene oxide, improving its dispersibility and conductivity.

[0036] In this invention, the molar ratio of β-diketone ligand, basic reagent and rare earth salt is 3-4:4-5:1, for example, it can be 3.5-4:4.5-5:1.

[0037] In this invention, the β-diketone ligand is benzoyltrifluoroacetone. The basic reagent is selected from at least one of triethylamine and pyridine, preferably triethylamine. The rare earth salt is a rare earth chloride, which can be anhydrous rare earth chloride or anhydrous rare earth chloride.

[0038] In this invention, the alcohol solution is a C1-C3 aqueous alcohol solution, which can be an aqueous methanol solution, an aqueous ethanol solution, or an aqueous isopropanol solution. Preferably, the alcohol solution is an aqueous methanol solution. In the alcohol solution, the volume ratio of alcohol to water is 1:8 to 12, preferably 1:9 to 11, and more preferably 1:10 to 11.

[0039] The ratio of the amount of rare earth elements in the alcohol-containing aqueous solution of β-diketone rare earth supramolecular to the volume of the alcohol-containing aqueous solution of β-diketone rare earth supramolecular can be 0.15 mmol: 60-75 mL.

[0040] The reaction temperature can be 15–35°C, for example, 25–35°C. The reaction time can be 9–15 h, preferably 10–15 h, and more preferably 12–13 h.

[0041] According to one embodiment of the present invention, a benzoyltrifluoroacetone ligand solution is mixed with an aqueous solution of a rare earth salt and reacted, as shown in the following reaction equation:

[0042]

[0043] Among them, Ln 3+ Selected from Eu 3+ La 3+ 、Sm 3+ and Gd 3+ One of them.

[0044] Preparation steps of modified graphene oxide

[0045] An alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules was mixed with graphene oxide powder and reacted at 75–100 °C. After the reaction was completed, the temperature was lowered, and the solid and liquid were separated. The separated solid was washed and dried to obtain the modified graphene oxide. The modified graphene oxide has a large number of wrinkles on its surface, which improves the dispersibility and conductivity of the graphene oxide.

[0046] In this invention, the mass ratio of rare earth elements in the β-diketone rare earth supramolecular to the mass of graphene oxide is 0.08–0.15 mmol:0.05 g, preferably 0.09–0.12 mmol:0.05 g, and more preferably 0.1–0.11 mmol:0.05 g.

[0047] The reaction temperature can be 75–100°C, preferably 85–100°C, and more preferably 90–100°C. The reaction time can be 4–8 hours, preferably 5–7 hours, and more preferably 5–6 hours.

[0048] After the reaction is complete, the mixture can be cooled to room temperature. Solid-liquid separation can be performed by centrifugation or filtration, preferably filtration, such as vacuum filtration. The separated solid can be washed with a C1-C3 alcohol, where the C1-C3 alcohol is an alkyl alcohol with 1-3 carbon atoms. For example, it can be washed with methanol, ethanol, or isopropanol. The washed solid is dried, preferably by vacuum drying, at a temperature of 50-80°C, preferably 60-70°C. The drying time can be 5-8 hours, preferably 5-7 hours, and more preferably 6-7 hours.

[0049] <Application>

[0050] The present invention also provides an application of modified graphene oxide in the preparation of battery electrodes.

[0051] The test methods used in the following embodiments and comparative examples are described below:

[0052] SEM testing: The tests were conducted using a Hitachi S-4800 scanning electron microscope from Japan.

[0053] Fluorescence spectroscopy: The tests were performed using a steady-state / transient fluorescence spectrometer, model FLS 920, manufactured by Edinburgh, UK.

[0054] Cyclic voltammetry test: The test was conducted using a CHI760E electrochemical workstation from Shanghai Chenhua Instrument Co., Ltd.

[0055] The electrochemical experiments were conducted using a three-electrode electrochemical workstation, with a glassy carbon electrode as the working electrode, a platinum wire electrode as the counter electrode, and a silver / saturated silver chloride electrode as the reference electrode. The electrolyte was a 0.1 mol / L tetrabutylammonium hexafluorophosphate CH₂Cl₂ solution, and the sample scan rate was 100 mV·s. -1 The concentration of modified graphene oxide was approximately 0.1 mol / L. The measured potential was corrected using ferrocene.

[0056] The raw materials used in the following examples are described below:

[0057] Graphene oxide: Shenzhen Qili Nanotechnology Co., Ltd. (manufacturer), QLC005 (model).

[0058] Example 1

[0059] Benzoyltrifluoroacetone (0.10 g, 0.46 mmol), triethylamine (0.06 g, 0.62 mmol), and 70 mL of methanol-water solution (methanol to water volume ratio of 1:10) were mixed and stirred for 10 min to obtain a ligand solution. 2 mL of LEuCl3·6H2O (0.06 g, 0.15 mmol) aqueous solution was added to the ligand solution and stirred at room temperature for 12 h to obtain an alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules.

[0060] Add 0.05 g of graphene oxide powder to 50 mL of the alcohol-containing aqueous solution of the β-diketone rare earth supramolecular obtained above, mix, and reflux for 6 h. After the reaction is complete, cool to room temperature, filter, wash the obtained solid powder with methanol 5 times, and dry the solid under vacuum at 60 °C for 6 h to obtain modified graphene oxide powder.

[0061] The obtained modified graphene oxide powder was characterized by scanning electron microscopy (SEM). The results are as follows: Figure 1 (b) shows the results compared to unmodified graphene oxide (SEM results are shown in [image]). Figure 1 Compared to (a), the rare earth europium supramolecular modified graphene oxide prepared in Example 1 has a large number of wrinkles on its surface, which increases the dispersibility of graphene oxide.

[0062] The cyclic voltammetric results of the obtained modified graphene oxide are shown in [reference needed]. Figure 2 .Depend on Figure 2 It can be seen that the electrochemical properties (oxidizing and reducing properties) of modified graphene oxide are improved. Modified graphene oxide exhibits a reversible reduction wave (E0) in the cyclic voltammogram. 1 / 2 =1.55V(vs Fc / Fc) + An irreversible reduction wave (Eredonset = 2.14V (vs Fc / Fc)) + An irregular oxidation wave (Eoxonset = 0.27V (vs Fc / Fc)) and an irregular oxidation wave (Eoxonset = 0.27V (vs Fc / Fc)) + )).

[0063] The fluorescence spectra of the obtained modified graphene oxide are shown in the figure. Figure 3 .Depend on Figure 3 It can be seen that the fluorescence intensity of modified graphene oxide is significantly enhanced compared with that of unmodified graphene oxide.

[0064] Example 2

[0065] The only difference from Example 1 is that the rare earth salt is LaCl3·6H2O.

[0066] The SEM results of the modified graphene oxide obtained in this embodiment are shown in [the figure]. Figure 4 (c) Figure 4 (a) shows the SEM results of unmodified graphene oxide. Compared with unmodified graphene oxide, the modified graphene oxide obtained in this example has a large number of wrinkles on its surface, which increases the dispersibility of graphene oxide.

[0067] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A modified graphene oxide, characterized in that, It is obtained by reacting β-diketone rare earth supramolecular elements with graphene oxide; wherein the mass ratio of rare earth elements in the β-diketone rare earth supramolecular elements to the mass of graphene oxide is 0.09–0.12 mmol:0.05 g. Among them, the β-diketone ligand in the β-diketone rare earth supramolecular is benzoyltrifluoroacetone; The method for preparing the modified graphene oxide includes the following steps: An alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules was mixed with graphene oxide powder and reacted at 75–100 °C for 4–8 h. After the reaction was completed, the temperature was lowered, the solid and liquid were separated, and the separated solid was washed and dried to obtain the modified graphene oxide. The preparation method described herein does not damage the structure of graphene oxide itself.

2. The modified graphene oxide according to claim 1, characterized in that, The rare earth element in the β-diketone rare earth supramolecular is selected from one of Eu, La, Sm and Gd.

3. A method for preparing modified graphene oxide as described in claim 1, characterized in that, Includes the following steps: An alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules was mixed with graphene oxide powder and reacted at 75–100 °C for 4–8 h. After the reaction was completed, the temperature was lowered, the solid and liquid were separated, and the separated solid was washed and dried to obtain the modified graphene oxide.

4. The preparation method according to claim 3, characterized in that, The alcohol-containing aqueous solution of the β-diketone rare earth supramolecular is prepared by the following steps: A β-diketone ligand, a basic reagent, and an alcohol solution are mixed to obtain a ligand solution; the ligand solution is then mixed with an aqueous solution of a rare earth salt and reacted to obtain an alcohol-containing aqueous solution of the β-diketone rare earth supramolecular.

5. The preparation method according to claim 4, characterized in that, The alkaline reagent is selected from at least one of triethylamine and pyridine; the rare earth salt is a rare earth chloride.

6. The preparation method according to claim 4, characterized in that, The molar ratio of β-diketone ligand, basic reagent and rare earth salt is 3-4:4-5:

1.

7. The preparation method according to claim 4, characterized in that, The alcohol solution is a solution formed by C1-C3 alcohol and water, wherein the volume ratio of C1-C3 alcohol to water is 1:8 to 12.

8. The preparation method according to claim 4, characterized in that, The specific steps include the following: An alcohol-containing aqueous solution of β-diketone rare earth supramolecular molecules was mixed with graphene oxide powder and reacted at 75–100 °C for 4–8 h. After the reaction was completed, the temperature was lowered, and the solid and liquid were separated. The separated solid was washed with C1-C3 alcohol and then dried to obtain the modified graphene oxide.

9. The application of the modified graphene oxide according to claim 1 in the preparation of battery electrodes.

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