A method for the visible light preparation of reduced graphene oxide in aqueous solution
By using a visible LED lamp and the organic dyes eosin Y and triethylamine to reduce graphene oxide in aqueous solution, the problems of high pollution and low yield in traditional methods were solved, and efficient and low-cost preparation of reduced graphene oxide was achieved. The prepared rGO has an excellent structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG AGRICULTURAL UNIVERSITY
- Filing Date
- 2024-06-20
- Publication Date
- 2026-05-15
AI Technical Summary
Existing methods for reducing graphene oxide require strong reducing agents, resulting in high pollution, difficulty in separation, and unsuitability for large-scale production. Traditional methods also have low yields, high costs, and are environmentally unfriendly.
Reduced graphene oxide was prepared by using a visible light LED lamp as a light source in an aqueous solution, combined with the organic dye eosin Y and triethylamine as photosensitizer and electron sacrificial agent, to reduce graphene oxide at room temperature and pressure.
A high-efficiency, low-cost, and pollution-free method for the preparation of reduced graphene oxide (rGO) at room temperature and pressure was achieved. The yield was high, and the prepared rGO structure was flat, thin, well-graphitized, and easy to separate.
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Figure CN118545705B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of reduced graphene oxide preparation technology, specifically to a method for preparing reduced graphene oxide using visible light in an aqueous solution. Background Technology
[0002] Reduced graphene oxide (rGO) is an important industrial raw material. rGO has similar properties to graphene and is a type of graphene produced by sp... 2 Two-dimensional carbon nanosheet structures composed of hybrid carbon atoms. Compared to other materials, rGO exhibits superior mechanical, thermal, optical, and electronic properties, as well as extremely high charge carrier mobility, optical transmittance, high thermal conductivity, and a large specific surface area, making it promising for a wide range of applications in energy catalysis, sensors, thermal conductivity, energy storage, composite materials, and medicine.
[0003] Existing methods for preparing graphene can be broadly categorized into physical and chemical methods. Physical methods mainly include epitaxial growth and mechanical exfoliation, while chemical methods primarily include chemical vapor deposition, organic synthesis, redox reactions, and electrochemical reduction. Among these methods, the redox method for preparing graphene is characterized by low cost, high yield, and the ability to be mass-produced, making it one of the effective approaches for graphene preparation.
[0004] The main steps in preparing graphene via redox reactions include converting graphite oxide into graphene oxide (GO) and reducing GO with a reducing agent. Currently, the main methods for preparing GO include the Staudemair method, the Brodie method, and the Hummers method. In the process of reducing GO to prepare graphene, current methods primarily use hydrazine and its derivatives, metal hydrides such as sodium borohydride, strong reducing agents such as strong acids and strong bases, and catalytic reduction. These methods suffer from harsh reduction conditions, excessively expensive reducing agents, pollution and hazards during the reaction process, and significant difficulties in wastewater treatment. They are not environmentally friendly and are difficult to separate, hindering the large-scale production of graphene. Therefore, there is a need to develop efficient, controllable, green, and inexpensive reduction methods.
[0005] Solar energy, as a clean energy source, delivers a significant amount of energy to the Earth's surface each year. Looking at the spectral composition of solar energy, over 50% of solar radiation energy is in the visible light region. Therefore, preparing rGO by exciting a certain type of material with visible light, causing electron transitions within the material, and then reducing GO on its surface, is a clean, efficient, inexpensive preparation method with broad application prospects. Summary of the Invention
[0006] This invention addresses the shortcomings of existing technologies, such as low yield, requirement for strong reducing agents, and high pollution, by providing a method for preparing reduced graphene oxide (rGO) in aqueous solution under visible light. This method uses an LED lamp simulating the visible light range of sunlight as a light source at room temperature and pressure. In a homogeneous aqueous solution system containing the organic dye eosin Y (water-soluble) as a photosensitizer and triethylamine as an electron sacrificial agent, industrial-grade graphene oxide (GO) is reduced to obtain rGO. This method overcomes the drawbacks of traditional preparation processes, such as low yield, requirement for strong reducing agents, and high pollution. The prepared rGO has a flat structure, thin thickness, and well-defined graphitization. It also offers advantages such as simple process, easy separation, high yield, low energy consumption, low cost, and no pollution.
[0007] The specific technical solution of the present invention is as follows:
[0008] A method for preparing reduced graphene oxide in solution under visible light includes the following steps:
[0009] First, at room temperature and pressure, add the organic dye Eosin Y (water-soluble, C) to the mixed solvent at a mass ratio of 1-3:1-3. 20 H6Br4Na2O5) and graphene oxide (industrial grade, 95% purity);
[0010] The mass-to-volume ratio of graphene oxide to the mixed solvent is 2-3:3-6 mg / mL, the volume percentage of triethylamine in the mixed solvent is 5%-10%, and the volume percentage of deionized water is 90%-95%.
[0011] The above substances are mixed evenly in proportion, and the system is placed under a visible white LED light source for illumination and stirred for 1-6 hours to prepare reduced graphene oxide; the visible white LED light source has λ≥420nm and 30W-120W.
[0012] The roles of each substance in the above reaction process are as follows:
[0013] Organic dye Eosin Y (water soluble, C 20 Reduced graphene oxide was prepared by reducing industrial-grade graphene oxide in aqueous solution using H6Br4Na2O5 as a photosensitizer and triethylamine as an electron sacrificial agent under visible white LED illumination.
[0014] The reaction mechanism in the above reaction process is as follows:
[0015] Under illumination, eosin Y (EY) will reach an excited state to generate a triplet state of EY. * EY * It will first be quenched by the abundant triethylamine, generating electrons to form EY. *- EY *-With a sufficiently strong reduction potential, excited-state electrons can be transferred to the surface of graphene oxide, reducing oxygen-containing functional groups, thereby reducing industrial-grade graphene oxide raw materials to obtain reduced graphene oxide.
[0016] The preferred method for preparing reduced graphene oxide according to the present invention includes the following steps:
[0017] First, organic dye Eosin Y and graphene oxide were added to a mixed solvent at a mass ratio of 1:1 under normal temperature and pressure; the mass-volume ratio of graphene oxide to the mixed solvent was 1:1.5 mg / mL, the volume percentage of triethylamine in the mixed solvent was 5%, and the volume percentage of deionized water was 95%.
[0018] The above substances were mixed evenly in proportion, and the system was placed under a visible white LED light source for illumination and stirred for 24 hours to prepare reduced graphene oxide; the visible white LED light source had λ≥420nm and 30×3W.
[0019] The reduced graphene oxide obtained above is in solution state. The subsequent processing steps are as follows: add 10 ml of anhydrous ethanol to every 10 mg of solution-state reduced graphene oxide, pour into a 50 ml centrifuge tube, sonicate for 10 minutes to clean, centrifuge at 10,000 rpm for 20 minutes, pour off the supernatant and take the bottom solid, repeat 10 times, place in a vacuum dryer at 60℃ for 1 hour with a vacuum degree of 5-10 Pa, grind to obtain reduced graphene oxide.
[0020] The reduced graphene oxide obtained above has 1-2 layers, a thickness of about 0.1-5 nanometers, a sheet diameter of 1-2 micrometers, a carbon content of 70%-85%, and an oxygen content of 15%-30%, providing excellent performance for specific industrial applications.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] This invention provides a method for preparing reduced graphene oxide in aqueous solution under visible light. The method uses an LED lamp simulating the visible light range of sunlight as a light source at room temperature and pressure. The resulting reduced graphene oxide has a flat structure, thin thickness, and well-preserved graphitization, with a significant reduction in oxygen-containing functional groups. This method overcomes the disadvantages of traditional preparation processes, such as low yield, requirement for strong reducing agents, and high pollution. It has the advantages of simple process, easy separation, high yield, low energy consumption, low cost, and no pollution. Attached Figure Description
[0023] Figure 1 The images shown are SEM images of rGO and raw material GO prepared in Example 1. Figures a and b are SEM images of GO at different magnifications, and figures c and d are SEM images of rGO at different magnifications.
[0024] Figure 2 AFM images of rGO were prepared for Example 1, where a, c, and d are AFM images of rGO, and b is a thickness distribution map of rGO;
[0025] Figure 3 In the image, ac is the TEM image of rGO prepared in Example 1, d is the HRTEM image, e is the SAED image, and f is the EDS linear scan and elemental distribution map.
[0026] Figure 4 XPS spectra of rGO and raw material GO prepared in Example 1, where a is the full XPS spectrum of rGO and GO, and b and c are the C6 spectra of rGO and GO, respectively. 1s XPS diagram;
[0027] Figure 5 XRD patterns of rGO and raw material GO prepared in Example 1;
[0028] Figure 6 Raman plots of rGO prepared in Example 1 and raw material GO;
[0029] Figure 7 FT-IR images of rGO and raw material GO prepared for Example 1;
[0030] Figure 8 UV-Vis images of rGO and raw material GO prepared in Example 1.
[0031] Figure 9 XPS images of rGO were prepared for Example 2, where a is the full XPS spectrum of rGO and b is the C60-C ... 1s XPS diagram;
[0032] Figure 10 FT-IR chromatograms of rGO were prepared for Example 3; Detailed Implementation
[0033] To enable those skilled in the art to more clearly understand the technical solutions of this application, the technical solutions of this application will be described in detail below with reference to specific embodiments. If specific experimental conditions are not specified in the embodiments, they are generally based on conventional conditions or conditions recommended by the reagent company.
[0034] The graphene oxide used in the following examples is high-quality industrial-grade graphene oxide from Shenzhen Suiheng Graphene Technology Co., Ltd. Detailed parameters are as follows: purity 95%, number of layers 1-3, thickness approximately 1 nanometer, sheet diameter 1-10 micrometers, morphology and color brownish-brown powder, carbon content approximately 48%, oxygen content approximately 42%, and peelability 95%. Other reagents and consumables used, unless otherwise specified, can be obtained commercially.
[0035] Example 1: Preparation of reduced graphene oxide
[0036] Place 20 mg of water-soluble eosin Y into a 60 mL test tube. Measure 1.5 mL of triethylamine and 28.5 mL of deionized water to form a 30 mL mixed solution and pour it into the test tube. Shake well, add a magnetic stir bar, and obtain a transparent homogeneous aqueous solution system. Add 20 mg of graphene oxide to the test tube, stir well, and seal with a rubber stopper.
[0037] The sample was then placed under an LED light source, wherein the visible white LED light source λ≥420nm, 30×3W; the magnetic stirrer was turned on and adjusted to 400 rpm, and the sample was stirred under light for 2 hours to prepare reduced graphene oxide.
[0038] After the reaction was completed, the solid was poured into a 50 mL centrifuge tube, 20 mL of anhydrous ethanol was added, and the tube was ultrasonically cleaned for 10 minutes. After centrifugation at 10,000 rpm for 20 minutes, the bottom solid was collected and the supernatant was poured off. This process was repeated 10 times. The tube was then placed in a vacuum dryer at 60 °C for 1 hour with a vacuum degree of 5-10 Pa. After drying, the tube was ground to obtain reduced graphene oxide.
[0039] like Figure 1 As shown, SEM can be used to see... Figure 1 The GO surfaces of a and b are rough with many wrinkles and are tightly stacked together; Figure 1 c and d show that the surface of rGO is much smoother and has large layers, indicating that the rGO surface formed by reducing GO is smooth and flat.
[0040] like Figure 2 As shown, Figure 2 a shows that the prepared rGO is flat. Figure 2 According to bd, the obtained reduced graphene oxide has 1-2 layers, a thickness of about 0.1-5 nanometers, and a sheet diameter of 1-2 micrometers.
[0041] like Figure 3 As shown, the TEM image results are consistent with the SEM image results, showing a layered structure with a smooth surface. HRTEM shows the crystal form, SAED shows diffraction spots, and linear scanning also shows that the surface C to O ratio is approximately 7:3.
[0042] like Figure 4 As shown, Figure 4 a's GO and rGO's C 1s and O 1s The XPS full scan spectrum shows that the C / O ratio of rGO is 6.16 and that of GO is 2.53, indicating that the oxygen-containing functional groups are greatly reduced after reduction. Furthermore, the carbon content of rGO is 70.34% and the oxygen content is 29.66%. Figure 4 c GO's C 1sIt shows a strong CO peak, while Figure 4 b rGO's C 1s The significant decrease in the CO peak indicates a reduction in the oxygen content on the rGO surface.
[0043] like Figure 5 As shown, the X-ray diffraction of GO showed sharp peaks at 2θ values of approximately 11.4° and 43°, corresponding to the (002) and (110) crystal planes; while rGO showed a characteristic broad peak near 24.5°, corresponding to the (002) crystal plane, indicating that rGO was prepared by GO reduction.
[0044] like Figure 6 As shown, two spectral bands, G and D, appear in the Raman spectra of GO and rGO. The G band in GO is broad, located at 1592 cm⁻¹. -1 Nearby, zone D is located at 1323cm. -1 Nearby. In rGO, the D peak shifts to 1347 cm⁻¹. -1 The G-band was moved to 1599cm. -1 The presence of this feature nearby indicates that the formed rGO has a relatively high degree of graphitization.
[0045] like Figure 7 As shown, at 3400cm -1 and 1410cm -1 The peaks at the left and right positions are the vibrational and deformation absorption peaks of -OH (hydroxyl group), respectively, at 1726 cm⁻¹. -1 The peaks at the left and right positions represent the stretching vibration absorption peaks of the C=O (carbonyl group), at 1226 cm⁻¹. -1 The peaks at the left and right positions represent the stretching vibration of CO (epoxy group), at 1052 cm⁻¹. -1 The peaks at the left and right positions represent the stretching vibration of CO (alkoxy group). After the reduction of GO to rGO, all oxygen-containing vibrational peaks show a significant decrease.
[0046] like Figure 8 As shown in the graph, the absorbance of GO is related to wavelength, which indicates that π-π * The absorption peak of the transition is located at approximately 220-230 nm, n-π * The shoulder peak of the transition is located at 260-290 nm, while the peak of rGO is observed around 270-295 nm, with a single peak corresponding to π-π. * There are no n-π* transitions.
[0047] Example 2: Preparation of reduced graphene oxide
[0048] Place 20 mg of water-soluble eosin Y into a 60 ml test tube. Measure 2 mL of triethylamine and 18 mL of deionized water to form a 20 mL mixed solution, pour it into the test tube, shake well, add a magnetic stir bar to obtain a transparent homogeneous solution system, add 10 mg of graphene oxide and stir well, and seal with a rubber stopper.
[0049] The sample was then placed under an LED light source, wherein the visible white LED light source λ≥420nm, 10×3W; the magnetic stirrer was turned on and adjusted to 400 rpm, and the sample was stirred under light for 6 hours to prepare reduced graphene oxide.
[0050] After the reaction was completed, the solid was poured into a 50 mL centrifuge tube, 10 mL of anhydrous ethanol was added, and the tube was ultrasonically cleaned for 10 minutes. After centrifugation at 10,000 rpm for 20 minutes, the bottom solid was collected and the supernatant was poured off. This process was repeated 10 times. The tube was then placed in a vacuum dryer at 60 °C for 1 hour with a vacuum degree of 5-10 Pa. After drying, the tube was ground to obtain reduced graphene oxide.
[0051] like Figure 9 As shown, the rGO prepared through Example 2 above, Figure 9 a C 1s and O 1s The XPS full-scan spectrum shows that rGO has a C / O ratio of 3.76, a carbon content of 83.39%, and an oxygen content of 16.61%. Figure 9 b rGO's C 1s The significant decrease in the CO peak indicates a reduction in the oxygen content on the rGO surface.
[0052] Example 3: Preparation of reduced graphene oxide
[0053] Place 10 mg of water-soluble eosin Y into a 60 ml test tube. Measure 1 mL of triethylamine and 14 mL of deionized water to form a 15 mL mixed solution, pour it into the test tube, shake well, add a magnetic stir bar, and obtain a transparent homogeneous aqueous solution system. Add 15 mg of graphene oxide and stir well. Seal with a rubber stopper.
[0054] The sample was then placed under an LED light source, wherein the visible white LED light source has a wavelength of λ≥420nm and a wavelength of 40×3W; the magnetic stirrer was turned on and set to 400 rpm, and the sample was stirred under light for 1 hour to prepare reduced graphene oxide.
[0055] After the reaction was completed, the mixture was poured into a 50 mL centrifuge tube, 15 mL of anhydrous ethanol was added, and the mixture was ultrasonically cleaned for 10 minutes. After centrifugation at 10,000 rpm for 20 minutes, the bottom solid was collected and the supernatant was poured off. This process was repeated 10 times. The mixture was then placed in a vacuum dryer at 60 °C for 1 hour with a vacuum degree of 5-10 Pa. After drying, the mixture was ground to obtain reduced graphene oxide.
[0056] like Figure 10As shown, the rGO prepared through Example 3 above, Figure 10 FT-IR display 3400cm -1 and 1410cm -1 The vibrational and deformation absorption peaks of the -OH (hydroxyl group) at the left and right positions, 1726 cm⁻¹ -1 The absorption peaks of the C=O (carbonyl) stretching vibration at positions 1226 cm⁻¹ are located to the left and right. -1 The CO (epoxy group) stretching vibration peaks at positions 1052 cm⁻¹ are located to the left and right. -1 The CO (alkoxy) stretching vibration peaks at both the left and right positions decreased sharply.
[0057] In summary, this method has pioneered the successful reduction of industrial-grade graphene oxide to obtain rGO with a relatively flat structure and thin thickness.
[0058] The above embodiments are one specific implementation method selected by the present invention. Ordinary changes and substitutions made by those skilled in the art within the scope of this technical solution should be included in the protection scope of the present invention.
Claims
1. A method for preparing reduced graphene oxide under visible light in an aqueous solution, characterized in that, Includes the following steps: 1) Add eosin Y and graphene oxide to a mixed solvent of water and triethylamine and mix thoroughly; In step 1), the mass ratio of eosin Y to graphene oxide is 1-3:1-3; the mass-volume ratio of graphene oxide to the mixed solvent is 2-3:3-6 mg / mL. 2) The reaction occurs under visible light. The above system was irradiated under a visible white LED light source and stirred for 1-6 hours to prepare reduced graphene oxide; the visible white LED light source had λ≥420nm and 30W-120W.
2. The method for preparing reduced graphene oxide in aqueous solution under visible light according to claim 1, characterized in that: In step 1), the volume percentage of triethylamine in the mixed solvent is 5%-10%, and the volume percentage of deionized water is 90%-95%.
3. The method for preparing reduced graphene oxide in aqueous solution under visible light according to claim 1 or 2, characterized in that: In step 1), the volume percentage of triethylamine in the mixed solvent is 5%, and the volume percentage of deionized water is 95%.
4. The method for preparing reduced graphene oxide in aqueous solution under visible light according to claim 1, characterized in that: The subsequent processing steps after step 2) are as follows: For every 10 mg of solution-state reduced graphene oxide, add 10 ml of anhydrous ethanol, pour into a 50 ml centrifuge tube, sonicate for 10 minutes to clean, centrifuge at 10,000 rpm for 20 minutes, after which pour off the supernatant and take the bottom solid, repeat 10 times, place in a vacuum dryer at 60°C for 1 hour with a vacuum degree of 5-10 Pa, grind to obtain reduced graphene oxide.
5. The reduced graphene oxide prepared by any one of claims 1-4, characterized in that: The reduced graphene oxide has 1-2 layers, a thickness of 0.1-5 nanometers, and a sheet diameter of 1-2 micrometers.
6. The reduced graphene oxide according to claim 5, characterized in that: The reduced graphene oxide has a carbon content of 70%-95% and an oxygen content of 5%-30%.