CN102580715A - Method for preparing zinc oxide/graphene composite from expanded graphite by stripping - Google Patents

Abstract

The invention discloses a method for preparing a zinc oxide/graphene composite by exfoliating expanded graphite, which relates to a preparation method of the zinc oxide/graphene composite. The invention aims to solve the problem of low photocatalytic activity of existing zinc oxide nanometer materials. The method of the present invention is as follows: 1. pretreatment of expanded graphite; 2. dissolving surfactant and zinc source in a solvent, then adding pretreated expanded graphite, and injecting the solution into the expanded graphite layer by means of vacuum assistance; 3. Solvothermal treatment; 4. Washing, centrifugation and drying to obtain the required zinc oxide/graphene composite with high photocatalytic activity. Compared with the existing ones, the photocatalytic activity of the zinc oxide/graphene composite of the invention is increased by 30%, and has the advantages of simple process, uniform distribution of zinc oxide, little environmental pollution, low cost and easy commercialization. The method of the invention is applied to the field of zinc oxide nano material preparation.

Description

A method for preparing zinc oxide/graphene composites by exfoliating expanded graphite

technical field

The invention relates to a method for preparing a zinc oxide/graphene composite.

Background technique

As an important semiconductor material, zinc oxide has been widely used in the fields of degrading various pollutants and inhibiting bacteria because of its stable performance, non-toxicity and low price. However, the application of zinc oxide also faces bottleneck problems that need to be solved urgently: the recombination probability of photogenerated carriers of zinc oxide itself is high; the utilization rate of sunlight is low. In order to solve these problems, researchers have tried various methods to improve the catalytic efficiency of ZnO. For example: People use various carbon materials (activated carbon, carbon nanotubes) to combine with zinc oxide to form zinc oxide/carbon composites. Carbon materials have good electrical conductivity and strong absorption of light, which can promote the degradation of organic pollutants.

Graphene is a new type of one-atom-thick two-dimensional graphite material. Graphene has excellent crystallinity and unique electronic, thermodynamic, and mechanical properties, and can be applied to many advanced materials and devices, such as thin film materials, energy storage materials, liquid crystal materials, mechanical resonators, etc. Therefore, more and more Many scholars have participated in the research on the synthesis and properties of graphene composites. Graphene-based composites exhibit excellent photocatalytic activity due to their good electrical conductivity and strong absorption of light. Reducing graphite oxide by chemical or other methods to obtain a graphene substrate is a commonly used method. During the oxidation of graphite oxide, the six-membered ring structure of graphite will be partially destroyed, resulting in irreparable defects, which will also be destroyed by graphene. Inheritance, which in turn affects the quality of graphene, and the construction method of graphene-based composite materials has many steps, which is not conducive to large-scale operation.

The existing sol-gel or hydrothermal method to prepare zinc oxide has the problems of easy photocorrosion and low photocatalytic activity in the photocatalytic process. The existing zinc oxide/graphene composite mostly uses graphite oxide as the graphene source, and the photocatalytic activity is 30%-50%.

Contents of the invention

The purpose of the present invention is to provide a method for preparing zinc oxide/graphene composite by exfoliating expanded graphite in order to solve the problem of low photocatalytic activity of existing zinc oxide nanomaterials.

A kind of method for preparing zinc oxide/graphene composite by exfoliation of expanded graphite of the present invention is finished according to the following steps: 1. Take by weight 1～3 parts of expanded graphite, 0.01～0.1 parts of surface Active agent, 0.5-2 parts of zinc source and 20-50 parts of solvent; 2. Expanded graphite pretreatment: first put the expanded graphite weighed in step 1 into a high-temperature furnace, continue to feed protective gas, and then heat up to 800 ℃～1200℃, heat treatment for 1min～24h, and then cool to room temperature to complete the pretreatment; 3. Mix the expanded graphite pretreated in step 2 with the acid solution at a mass volume ratio of 1～5g:100mL, and heat at 110℃ Under the condition of ~140°C, reflux for 6-14h, collect the precipitate, then wash the precipitate with deionized water or absolute ethanol until the pH is 7.0, and then vacuum dry at a temperature of 40°C-100°C for 1-48h; 4. Steps 1. The surfactant and zinc source weighed are dissolved in the solvent weighed in step 1, and after mixing evenly, a mixed solution is obtained; 5. Put the expanded graphite processed in step 3 into a vacuum filtration device, Under the condition of 0～-0.05MPa, inject the mixed solution obtained in step 4 into the vacuum filtration device, and then heat reaction at 100℃～220℃ for 1～24h to obtain the product; 6. The product obtained in step 5 Centrifuge and wash with deionized water or absolute ethanol for 1 to 5 times, and then vacuum-dry the solid phase obtained by centrifugation at a temperature of 40°C to 100°C for 1 to 48 hours to obtain a zinc oxide/graphene composite with high photocatalytic activity ; Wherein, the protective gas flow rate in step 2 is 30～2000mL/min; The vacuum degree of the vacuum drying described in step 3 and step 6 is 0～-0.05MPa; The volume mass of the mixed solution and expanded graphite added in step 5 The ratio is 20-40mL:0.1g.

The effect of the present invention is: the present invention adopts expanded graphite as the source of graphene, and its source is extensive and cheap, and the photocatalytic activity of the zinc oxide/graphene compound that the method for the present invention prepares is compared with existing zinc oxide/graphene Compared with the compound, it is improved by 30%, and on the other hand, the cost of synthesizing two-dimensional graphene nano-carbon materials is greatly reduced. The existence of graphene can significantly improve the stability and photocatalytic activity of zinc oxide; and the graphene prepared from expanded graphite has fewer defects, and the electrical conductivity is obviously excellent. Graphite obtained by reducing graphite oxide. Therefore, the zinc oxide/graphene composite material obtained through the intercalation of expanded graphite in the present invention has stable and excellent photocatalytic performance.

Description of drawings

Fig. 1 is the X-ray diffraction spectrogram of the zinc oxide/graphene nanocomposite material that specific embodiment 12 prepares;

Fig. 2 is the transmission electron micrograph of the zinc oxide/graphene nanocomposite material prepared by specific embodiment 12;

为试验组的吸光度曲线。Fig. 3 is the zinc oxide/graphene nanocomposite material prepared by specific embodiment 12 and the catalytic effect evaluation of Degussa P25 degradation organic pollutant; Wherein is the absorbance curve of the control group,

is the absorbance curve of the test group.

Detailed ways

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific embodiment one: a kind of method for preparing zinc oxide/graphene composite by exfoliation of expanded graphite of the present embodiment is finished according to the following steps: one, take by weight 1～3 parts of expanded graphite, 0.01 to 0.1 parts of surfactant, 0.5 to 2 parts of zinc source and 20 to 50 parts of solvent; 2. Pretreatment of expanded graphite: first put the expanded graphite weighed in step 1 into a high temperature furnace, and continue to pass through the protection Then heat up to 800℃～1200℃, heat treatment for 1min～24h, and then cool to room temperature to complete the pretreatment; 3. The mass volume ratio of expanded graphite and acid solution after the pretreatment in step 2 is 1～5g:100mL Proportional mixing, under the condition of 110℃～140℃, reflux for 6～14h, collect the precipitate, then wash the precipitate with deionized water or absolute ethanol until the pH is 7.0, and then vacuum dry at 40℃～100℃ for 1～ 48h; 4. Dissolve the surfactant and zinc source weighed in step 1 in the solvent weighed in step 1. After mixing evenly, a mixed solution is obtained; 5. Put the expanded graphite processed in step 3 into a vacuum pump In the filter device, under the condition that the vacuum degree is 0～-0.05MPa, inject the mixed solution obtained in step 4 into the vacuum filter device, and then thermally react at 100°C-220°C for 1-24h to obtain the product; 6. Wash the product obtained in step 5 by centrifugation for 1 to 5 times with deionized water or absolute ethanol, and then vacuum-dry the solid phase obtained by centrifugation at a temperature of 40°C to 100°C for 1 to 48 hours to obtain a highly photocatalytically active oxidation product. Zinc/graphene composite; wherein, the protective gas flow in step 2 is 30～2000mL/min; the vacuum degree of vacuum drying described in step 3 and step 6 is 0～-0.05MPa; the mixed solution added in step 5 The volume mass ratio with expanded graphite is 20-40mL:0.1g.

This embodiment adopts expanded graphite as the source of graphene, which has a wide range of sources and is cheap. The photocatalytic activity of the zinc oxide/graphene composite prepared by the method of this embodiment is compared with that of the existing zinc oxide/graphene composite It has increased by 30%, and on the other hand, the cost of synthesizing two-dimensional graphene nano-carbon materials has been greatly reduced. The existence of graphene can significantly improve the stability and photocatalytic activity of zinc oxide; and the graphene prepared from expanded graphite has fewer defects, and the electrical conductivity is obviously excellent. Graphite obtained by reducing graphite oxide. Therefore, the zinc oxide/graphene composite material obtained through the intercalation of expanded graphite in this embodiment has stable and excellent photocatalytic performance.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that the expanded graphite in step 1 has a mesh size of 100, 140, 200, 250, 300, 350, 500, 1000, 5000 or 8000. Other steps and parameters are the same as those in Embodiment 1.

Specific embodiment three: this embodiment is different from specific embodiments one to two: the surfactant described in step one is cetyl trimethyl ammonium bromide, cetyl dimethyl benzyl ammonium bromide, Cetyl alcohol polyoxyethylene ether group dimethyl octyl ammonium chloride, lauryl alcohol polyoxyethylene ether group dimethyl methyl ammonium chloride, octylphenol polyoxyethylene ether group dimethyl decyl bromide ammonium chloride, octylphenol polyoxyethylene ether dimethyl decyl ammonium chloride, cetyl alcohol polyoxyethylene ether dimethyl octyl ammonium chloride, sodium lauryl sulfate, lauryl Sodium Sulfonate, Sodium Cetylbenzene Sulfonate, Sodium Octadecyl Sulfate, Sodium N-Oleoyl Polypeptide, Sodium Sulfate of Fatty Alcohol Polyoxyethylene Ether, Sodium Fatty Alcohol Polyoxyethylene Ether Sulfosuccinate Disodium, EO20PO70EO20 (P123), EO106PO70EO106 (F127), lauryl dimethyl amine oxide, coco alkyl dimethyl amine oxide, dodecyl dimethyl amine oxide, dodecyl dihydroxyethyl amine oxide Amine, myristyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, octadecyl dimethyl amine oxide, octadecyl dihydroxyethyl amine oxide, polyvinylpyrrolidone, Propylene glycol polyoxypropylene polyoxyethylene ether, alcohol polyoxyethylene polyoxypropylene ether, polyurethane polyoxypropylene polyoxypropylene ether, polyethylene glycol monooleate, octadecyl ethylene urea, coconut oil reduced alcohol, ten Hexaol, Oleyl Alcohol, Cetyl Alcohol, Nonylphenol, Octylphenol, Octylcresol, Glycerin, Pentaerythritol, Sorbitol, Ethanolamine, Isopropanolamine, Sucrose, Lauric Acid, Coco Fatty Acid, Myristic Acid, Palmitic, Oleic or Stearic Acid. Other steps and parameters are the same as those in Embodiments 1 to 2.

Specific embodiment four: this embodiment is different from one of specific embodiments one to three: the zinc source described in step one is zinc chloride, zinc sulfate, zinc nitrate, uranyl zinc acetate, zinc acetate, tetracyano zincate Potassium, zinc fluoride, zinc fluorosilicate, zinc hydrogen hydride, zinc oxide, zinc chloride, zinc cyanide, zinc bromide, zinc sulfide, zinc thiocyanate, zinc stearate, zinc iodide, zinc phosphide , zinc dihydrogen phosphate, zinc phosphate, zinc peroxide, zinc dithionite or zinc molybdate. Other steps and parameters are the same as those in Embodiments 1 to 3.

Embodiment 5: This embodiment is different from Embodiment 1 to Embodiment 4 in that: the solvent described in step 1 is deionized water, methanol with a mass percentage content of 98%, absolute ethanol or acetone. Other steps and parameters are the same as in one of the specific embodiments 1 to 4.

Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is that the protective gas described in step 2 is nitrogen, argon, helium, carbon monoxide, hydrogen, or several of them mixed in any ratio. Other steps and parameters are the same as one of the specific embodiments 1 to 5.

Embodiment 7: This embodiment is different from Embodiment 1 to Embodiment 6 in that: the reactor described in step 2 is a high-temperature tube furnace or a muffle furnace. Other steps and parameters are the same as one of the specific embodiments 1 to 6.

Embodiment 8: This embodiment differs from Embodiments 1 to 7 in that: the temperature is raised to 900°C to 1000°C in step 2. Other steps and parameters are the same as one of the specific embodiments 1 to 7.

Embodiment 9: This embodiment differs from Embodiment 1 to Embodiment 8 in that the acid solution described in Step 3 is nitric acid, hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid or oleum. Other steps and parameters are the same as those in Embodiments 1 to 8.

Embodiment 10: This embodiment is different from Embodiment 1 to Embodiment 9 in that: the vacuum drying at a temperature of 60° C. to 80° C. for 1 to 48 hours is described in Step 3. Other steps and parameters are the same as one of the specific embodiments 1 to 9.

Embodiment 11: This embodiment differs from Embodiments 1 to 10 in that: the centrifugation conditions described in step 6 are: the centrifugal speed is 3000-12000 rpm/min, and the centrifugation time is 1-30 min. Other steps and parameters are the same as those in Embodiments 1 to 11.

Specific embodiment 12: a kind of method for preparing zinc oxide/graphene compound by exfoliation of expanded graphite of the present embodiment is finished according to the following steps: one, take by weight the 140 order expanded graphite of 2g, 0.05g of cetyltrimethylammonium bromide, 1g of zinc oxide and 30g of deionized water; 2. Expanded graphite pretreatment; first put the 140-mesh expanded graphite weighed in step 1 into a high-temperature tube furnace , continue to feed nitrogen, then heat up to 1000°C, heat treatment for 5min, and then cool to room temperature; 3. Mix 2g of 140 mesh expanded graphite and 100mL of oleum after heat cooling in step 2, and reflux at 120°C 14h, collect the precipitate, then wash the precipitate with deionized water until the pH is 7.0, and then dry it in vacuum for 24h at a temperature of 70°C and a vacuum of -0.05MPa; Trimethylammonium bromide and zinc oxide are dissolved in the deionized water weighed in step 1, and after mixing evenly, a mixed solution is obtained; 5. Put 0.1g of 140 mesh expanded graphite weighed in step 1 into a vacuum filtration device , under the condition of a vacuum degree of -0.05MPa, inject 40mL of the mixed solution obtained in step 4 into the vacuum filtration device, and then thermally react at 180°C for 24h to obtain the product; 6. Use anhydrous Centrifuge and wash the filtrate with ethanol at 12000rpm/min for 15min, collect the precipitate, and then dry it for 48h at a temperature of 60°C and a vacuum of -0.05MPa to obtain a zinc oxide/graphene composite; wherein, step 2 The protective gas flow rate in the system is 1000mL/min.

The structure of zinc oxide in this embodiment is a one-dimensional rod-like structure.

The crystal phase and composition of the zinc oxide/graphene composite prepared in this embodiment are observed by using the D/max-IIIB X-ray diffractometer of Rigaku Corporation of Japan, as shown in Figure 1. It can be seen from the figure that the crystallization of zinc oxide nanoparticles more complete.

Adopt JEOL JEM-2100 transmission electron microscope of Japan Electronics Corporation to observe the morphology and structure of the zinc oxide/graphene composite prepared in this embodiment, as shown in Figure 2, as can be seen from Figure 2, the zinc oxide nanometer prepared in this embodiment Rods were successfully inserted into the middle of graphene sheets to form ZnO/graphene composites.

The zinc oxide/graphene compound that present embodiment is made carries out application test:

Test conditions: Test group: Methylene blue was used as the photocatalytic target degradation product, put into the photocatalytic reactor, a 40W ultraviolet lamp was used as the ultraviolet light source, the wavelength of the ultraviolet light source was 365nm, and the photocatalytic reactor was placed at a distance of 15cm from the light source; Control group: Commercial Degussa P25 powder was used as the photocatalytic target degradation product, and other conditions were consistent with the test group;

The specific test steps are as follows:

At room temperature, mix 50mL of 10mg/L methylene blue aqueous solution and 0.1g of catalyst evenly, and let it stand in a dark environment. When the methylene blue aqueous solution reaches the adsorption-desorption equilibrium, place it in a photocatalytic reactor under ultraviolet light irradiation Carry out the reaction, take a sample test every 10min, measure the photodegradation experiment of methylene blue (MB) with Japan SHIMADZU company UV-2550 ultraviolet-visible spectrophotometer, observe the change of its absorbance at λ=664nm.

At the same time, the control group was tested under the same conditions as the test group.

The results are shown in FIG. 3 . It can be seen from FIG. 3 that the zinc oxide/graphene composite prepared in this embodiment can effectively degrade methylene blue, and the photocatalytic activity is 65%.

Claims (10)

1. A method for preparing zinc oxide/graphene composite by exfoliation of expanded graphite is characterized in that the method for preparing zinc oxide/graphene composite by expanded graphite is completed by the following steps: one, by weight and number ratio Weigh 1 to 3 parts of expanded graphite, 0.01 to 0.1 parts of surfactant, 0.5 to 2 parts of zinc source and 20 to 50 parts of solvent; 2. Pretreatment of expanded graphite: first weigh the expanded graphite in step 1 Put it into a high-temperature furnace, continuously feed the protective gas, then raise the temperature to 800°C~1200°C, heat treatment for 1min~24h, and then cool to room temperature to complete the pretreatment; Mix at a mass volume ratio of 1-5g: 100mL, reflux at 110°C-140°C for 6-14 hours, collect the precipitate, then wash the precipitate with deionized water or absolute ethanol until the pH is 7.0, and then reflux at 40°C Vacuum drying at a temperature of ~100°C for 1 to 48 hours; 4. Dissolve the surfactant and zinc source weighed in step 1 in the solvent weighed in step 1, and mix well to obtain a mixed solution; 5. The expanded graphite after the third treatment is put into the vacuum filtration device, and under the condition of vacuum degree of 0~-0.05MPa, inject the mixed solution obtained in step 4 into the vacuum suction device, and then thermally react at 100°C~220°C 1 to 24 hours to obtain the product; 6. Centrifuge and wash the product obtained in step 5 with deionized water or absolute ethanol for 1 to 5 times, and then vacuum-dry the solid phase obtained by centrifugation at a temperature of 40°C to 100°C 1 to 48 hours to obtain a zinc oxide/graphene composite with high photocatalytic activity; wherein, the flow rate of the protective gas in step 2 is 30 to 2000mL/min; the vacuum degree of vacuum drying described in step 3 and step 6 is 0 to - 0.05MPa; The volume mass ratio of the mixed solution added in step 5 and expanded graphite is 20～40mL: 0.1g. 2. A kind of method for preparing zinc oxide/graphene compound by exfoliation of expanded graphite according to claim 1, is characterized in that the order number of expanded graphite described in step 1 is 100,140,200,250,300, 350, 500, 1000, 5000 or 8000. 3. A kind of method for preparing zinc oxide/graphene composite by exfoliation of expanded graphite according to claim 1, is characterized in that the tensio-active agent described in step one is cetyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, cetyl Alkyl dimethyl benzyl ammonium bromide, cetyl polyoxyethylene ether dimethyl octyl ammonium chloride, lauryl polyoxyethylene ether dimethyl methyl ammonium chloride, octylphenol poly Oxyethylene ether dimethyl decyl ammonium bromide, octylphenol polyoxyethylene ether dimethyl decyl ammonium chloride, cetyl alcohol polyoxyethylene ether dimethyl octyl ammonium chloride, Sodium Lauryl Sulfate, Sodium Lauryl Sulfonate, Sodium Cetylbenzene Sulfonate, Sodium Octadecyl Sulfate, Sodium N-Oleoyl Polypeptide, Sodium Fatty Alcohol Polyoxyethylene Ether Sulfate, Fat Disodium alcohol polyoxyethylene ether sulfosuccinate monoester, EO20PO70EO20, EO106PO70EO106, lauryl dimethylamine oxide, cocoalkyl dimethylamine oxide, dodecyl dimethylamine oxide, lauryl Dihydroxyethyl amine oxide, tetradecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, octadecyl dimethyl amine oxide, octadecyl dihydroxyethyl amine oxide, Polyvinylpyrrolidone, propylene glycol polyoxypropylene polyoxyethylene ether, alcohol polyoxyethylene polyoxypropylene ether, polyurethane polyoxypropylene polyoxypropylene ether, polyethylene glycol monooleate, octadecyl ethylene urea, coconut Oil reduced alcohol, cetyl alcohol, oleyl alcohol, cetyl alcohol, nonylphenol, octylphenol, octylcresol, glycerin, pentaerythritol, sorbitol, ethanolamine, isopropanolamine, sucrose, lauric acid, coconut fatty acid , myristic, palmitic, oleic or stearic acids. 4. A kind of method for preparing zinc oxide/graphene composite by exfoliation of expanded graphite according to claim 1, is characterized in that the zinc source described in step one is zinc chloride, zinc sulfate, zinc nitrate, uranyl acetate Zinc, zinc acetate, potassium tetracyanozinate, zinc fluoride, zinc fluorosilicate, zinc hydrogen hydride, zinc oxide, zinc chloride, zinc cyanide, zinc bromide, zinc sulfide, zinc thiocyanate, stearic acid Zinc, zinc iodide, zinc phosphide, zinc dihydrogen phosphate, zinc phosphate, zinc peroxide, zinc dithionite, or zinc molybdate. 5. a kind of method that prepares zinc oxide/graphene composite by exfoliation of expanded graphite according to claim 1, is characterized in that the solvent described in step one is deionized water, the methyl alcohol that mass percentage content is 98%, no water ethanol or acetone. 6. A kind of method for preparing zinc oxide/graphene composite by exfoliation of expanded graphite according to claim 1, is characterized in that the protective gas described in step 2 is nitrogen, argon, helium, carbon monoxide and hydrogen One or several of them are mixed in any ratio. 7. A kind of method for preparing zinc oxide/graphene compound by exfoliation of expanded graphite according to claim 1, is characterized in that the high-temperature furnace described in step 2 is a high-temperature tube furnace or a muffle furnace. 8 . A method for preparing zinc oxide/graphene composites by exfoliating expanded graphite according to claim 1 , characterized in that the temperature in step 2 is raised to 900° C. to 1000° C. 9. A kind of method for preparing zinc oxide/graphene composite by exfoliation of expanded graphite according to claim 1, is characterized in that the acid solution described in step 3 is nitric acid, hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid or oleum . 10 . A method for preparing zinc oxide/graphene composites by exfoliating expanded graphite according to claim 1 , characterized in that the step 3 is vacuum-dried at a temperature of 60° C. to 80° C. for 1 to 48 hours. 11 .

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