CN111892043A - A kind of method for preparing reduced graphene oxide by one-pot method - Google Patents

Abstract

The invention discloses a method for preparing reduced graphene oxide by a one-pot method, which specifically includes the following steps: at room temperature, adding a strong oxidant to a strong acid solution containing graphite, oxidizing to obtain graphite oxide, adding water to quench the reaction, and quenching the reaction with acid Washing, sonicating, and centrifuging to obtain a graphene oxide slurry; adding a strong alkali compound to the graphene oxide slurry, and reacting at 40-180 ° C for 0.5-24 h to obtain an alkaline reduced graphene oxide suspension; After the reduced graphene oxide suspension is dried, activated by microwave, washed with water until neutral and free of impurities, and then dried to obtain reduced graphene oxide powder. In the oxidation stage, the graphite oxide solution is directly synthesized at room temperature, after acid washing, ultrasonication and centrifugation, alkali is added for rapid reduction, and after microwave activation, the reduced graphene oxide with high porosity and high specific surface area is obtained by washing; The method simplifies the oxidation process, realizes the rapid synthesis of reduced graphene oxide, reduces energy consumption, and shortens the synthesis time.

Description

A kind of method for preparing reduced graphene oxide by one-pot method

technical field

The invention belongs to the technical field of graphene materials, and in particular relates to a method for preparing reduced graphene oxide by a one-pot method.

Background technique

Graphene is the earliest discovered two-dimensional single-atom material. Due to its excellent physical and chemical properties, it has been maintained a high research boom by researchers since 2004. Among the known methods for synthesizing graphene composites, the modification and functionalization of graphene oxide (GO) containing oxygen-rich groups and active sites is the most common and largest scale method. As the most extensive derivative of graphene, graphene oxide not only plays an important role in supercapacitors and electrodes, but also is widely used in sensors, chemical and biological markers, catalyst carriers, polymer fillers and other fields.

Graphene oxide is a thin layer product of layered graphite intercalated and exfoliated by high-valent metal salts with strong oxidizing properties such as potassium permanganate and potassium dichromate in a strong acid atmosphere. Among the numerous oxidation methods, the classical Hummers method has been widely introduced because of its safety, mainly through edge oxidation at 0 ℃, deep oxidation at 35 ℃ and hydrolysis at 98 ℃ to achieve the purpose of oxidative stripping. However, whether it is the classic or improved Hummers method, it is inseparable from the low temperature or high temperature atmosphere provided by the outside world, which greatly increases the manufacturing cost of graphene oxide and puts forward higher requirements for equipment. At the same time, the preparation of graphene oxide by the classical or improved Hummers method requires transferring the reaction solution to a higher temperature, which is cumbersome and entails certain risks. For example, Chinese patent a kind of preparation method of graphene oxide (patent number is CN 106115669 A, application date is 20160620) discloses a kind of preparation method of graphene oxide, in this method, it is necessary to add high temperature oxidation system below 10 ℃ Potassium manganate, after reacting for 2-4 days at room temperature, continue to react at 80 °C for 2-5 h, and then add hydrogen peroxide and water to quench the reaction. This method not only has a long reaction time, but also requires external continuous supply of energy, which greatly increases the cost of synthesis. At the same time, the subsequent filtration and purification process is not only time-consuming and labor-intensive, but also tends to generate more acid-containing wastewater.

In view of the problems of long reaction time and high energy consumption in the prior art, it is extremely necessary to study a preparation method of reduced graphene oxide with high efficiency and low consumption.

SUMMARY OF THE INVENTION

In view of the above problems, the object of the present invention is to provide a method for preparing reduced graphene oxide by one-pot method.

The object of the present invention is achieved in this way, a one-pot method for preparing reduced graphene oxide, including oxidation reaction, reduction reaction and drying activation, specifically includes the following steps:

(1) Oxidation reaction: at room temperature, a strong oxidant is added to a strong acid solution containing graphite to obtain graphite oxide after oxidation, and water is added to quench the reaction to obtain a graphene oxide slurry through pickling, ultrasonication and centrifugation;

(2) reduction reaction: adding a strong base compound to the graphene oxide slurry to carry out a reduction reaction, and obtaining an alkaline reduced graphene oxide suspension after the reaction is completed;

(3) Microwave activation: after drying the reduced graphene oxide suspension, it is activated by microwave, washed with water until neutral and free of impurities, and then dried to obtain reduced graphene oxide powder.

The beneficial effects of the present invention are:

In this method, graphite oxide solution is directly synthesized at room temperature in the oxidation stage, after acid washing, ultrasonication and centrifugation, alkali is added for rapid reduction, directly dried and then activated by microwave, and washed to obtain reduced graphite oxide with high porosity and high specific surface area. The method avoids the need for continuous external cooling or heating in the traditional oxidation stage, simplifies the oxidation process, realizes the rapid synthesis of reduced graphene oxide, reduces energy consumption, and shortens time. The whole redox process of the method has short cycle, simple procedure, simple equipment requirements, and is easy to realize continuous and large-scale operation; in addition, after the alkali-containing reduced graphene oxide is activated by microwave, its specific surface area and Porosity, its products can be widely used in adsorption, supercapacitors and graphene-based composite materials and other fields.

Description of drawings

Fig. 1 is the XRD figure of the reduced graphene oxide prepared by the embodiment of the present invention 1;

Fig. 2 is the Raman diagram of the reduced graphene oxide prepared by the embodiment of the present invention 1;

3 is an XPS diagram of the reduced graphene oxide prepared in Example 1 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments. It should be pointed out that the following examples are only to illustrate the present invention by way of example examples, but the protection of the present invention is not limited to this. Personnel take the present invention as the spirit, and the equivalent replacements made by the present invention all fall into the protection scope of the present invention.

A method for preparing reduced graphene oxide by a one-pot method of the present invention includes oxidation reaction, reduction reaction and microwave activation, and specifically includes the following steps:

(1) Oxidation reaction: at room temperature, a strong oxidant is added to a strong acid solution containing graphite to obtain graphite oxide after oxidation, and water is added to quench the reaction to obtain a graphene oxide slurry through pickling, ultrasonication and centrifugation;

(2) reduction reaction: adding a strong base compound to the graphene oxide slurry to carry out a reduction reaction, and obtaining an alkaline reduced graphene oxide suspension after the reaction is completed;

(3) Microwave activation: after drying the reduced graphene oxide suspension, it is activated by microwave, washed with water until neutral and free of impurities, and then dried to obtain reduced graphene oxide powder.

In the step 1, the room temperature is 10-40 °C, and the oxidation reaction time is 0.5-48 h.

In the step 1, the strong oxidant is one or more combinations of potassium permanganate, potassium dichromate or potassium ferrate, and the ratio of the combination is 1-X:X (X=0～ 1), the weight ratio of the strong oxidant to graphite is 1~6:1.

In the step 1, the ultrasonic power is 10-500 W, and the ultrasonic time is 30-300 min.

In the step 1, the acid used for pickling is hydrochloric acid with a concentration of 5-20%, until the solution no longer contains metal ions.

In the step 2, the reduction reaction temperature is 40-180 °C, and the reaction time is 0.5-24 h.

In described step 2, described strong base compound is the combination of one or more of potassium hydroxide, sodium hydroxide or ammoniacal liquor, the add-on of strong base＞the amount of acid neutralization in graphene oxide slurry, acid After being completely neutralized, continue to add strong alkali to make the pH of the alkaline reduced graphene oxide suspension ≥ 9.

In the step 3, the drying method is any one or a combination of vacuum drying, freeze drying or spray drying.

In the step 3, the microwave activation power is 100-10000 W, and the microwave treatment time is 0.5-300 min.

In the steps 1-3, the water is deionized water or ultrapure water.

The steps 1-2 are all completed in the same container, and the container is a container that can be stirred and heated.

The present invention will be further described below in conjunction with the examples.

Example 1

At a temperature of 25 °C, 1 g of flake graphite and 0.5 g of sodium nitrate were added to 23 mL of concentrated sulfuric acid and stirred for 30 min, then 3 g of potassium permanganate was slowly added, and the reaction was continued for 2 h, and then deionized water was slowly added to terminate the reaction. , and then dropwise add hydrogen peroxide until no bubbles are generated to obtain a graphite oxide solution. The obtained graphite oxide was acid-washed with 1000ml of 10% hydrochloric acid, and then treated in ultrasonic with a power of 200W for 1 hour. After centrifugation, 112g of potassium hydroxide was added, and the reaction was stirred in a water bath at 80°C for 2 hours. The precipitation was directly spray-dried into powder, reacted in a 1000W microwave oven for 30min, washed with water to neutrality, and freeze-dried to obtain reduced graphene oxide powder. Its XRD pattern, Raman diagram and XPS diagram are shown in Figures 1-3 respectively. .

Example 2

At a temperature of 30 °C, 1 g of flake graphite and 0.5 g of sodium nitrate were added to 23 mL of concentrated sulfuric acid and stirred for 40 min, then 6 g of potassium dichromate was slowly added, and the reaction was continued for 12 h, and then deionized water was slowly added to terminate the reaction. Hydrogen peroxide was then added dropwise until no bubbles were generated to obtain a graphite oxide solution. The obtained graphite oxide solution was acid-washed with 2000ml of 5% hydrochloric acid, and then treated in ultrasonic with a power of 400W for 3 hours. After centrifugation, 224g of sodium hydroxide was added, and the reaction was stirred in a water bath at 60°C for 8 hours. The obtained precipitate was directly vacuum-dried into powder, reacted in a 100W microwave oven for 60 min, washed with water until neutral, and vacuum-dried to obtain reduced graphene oxide powder.

Example 3

At a temperature of 40 °C, 1 g of flake graphite and 0.5 g of sodium nitrate were added to 23 mL of concentrated sulfuric acid and stirred for 45 min, then 5 g of potassium permanganate was slowly added, and the reaction was continued for 24 h, and then deionized water was slowly added to terminate the reaction. Hydrogen peroxide was then added dropwise until no bubbles were generated to obtain a graphite oxide solution. After the obtained graphite oxide solution was pickled with 1000ml of 15% hydrochloric acid, the obtained graphene oxide was treated in an ultrasonic wave with a power of 300W for 2h, then centrifuged, 169g of sodium hydroxide and 100g of potassium hydroxide were added, and The reaction was stirred in a water bath at 100°C for 1 h, and the resulting precipitate was directly freeze-dried into powder. After being reacted in a 10,000 W microwave oven for 0.5 min, washed with water until neutral, and freeze-dried to obtain reduced graphene oxide powder.

Example 4

At a temperature of 10 °C, 1 g of flake graphite and 0.5 g of sodium nitrate were added to 23 mL of concentrated sulfuric acid and stirred for 50 min, then 1 g of potassium permanganate was slowly added, and the reaction was continued for 10 h, and then deionized water was slowly added to terminate the reaction. Hydrogen peroxide was then added dropwise until no bubbles were generated to obtain a graphite oxide solution. The obtained graphite oxide was acid-washed with 1000ml of 18% hydrochloric acid, and then treated in ultrasonic with a power of 500W for 1 hour. After centrifugation, 112g of potassium hydroxide was added, and the reaction was stirred in a water bath at 70°C for 4 hours. The precipitation was directly spray-dried into powder, reacted in a 500W microwave oven for 100 min, washed with water to neutrality, and freeze-dried to obtain reduced graphene oxide powder.

Example 5

At a temperature of 15 °C, 1 g of flake graphite and 0.5 g of sodium nitrate were added to 23 mL of concentrated sulfuric acid and stirred for 25 min, then 2 g of potassium dichromate was slowly added, and the reaction was continued for 8 h, and then deionized water was slowly added to terminate the reaction. Hydrogen peroxide was then added dropwise until no bubbles were generated to obtain a graphite oxide solution. The obtained graphite oxide solution was acid-washed with 2000ml of 8% hydrochloric acid, and then treated in ultrasonic with a power of 500W for 3 hours. After centrifugation, 78g of sodium hydroxide, 53g of potassium hydroxide and 116g of ammonia water were added. The reaction was stirred in the pot for 7 hours, and the obtained precipitate was directly vacuum-dried into powder, which was reacted in a 3000W microwave oven for 7 minutes, washed with water until neutral, and vacuum-dried to obtain reduced graphene oxide powder.

Example 6

At a temperature of 20 °C, 1 g of flake graphite and 0.5 g of sodium nitrate were added to 23 mL of concentrated sulfuric acid and stirred for 30 min, then 4 g of potassium permanganate was slowly added, and the reaction was continued for 16 h, and then deionized water was slowly added to terminate the reaction. Hydrogen peroxide was then added dropwise until no bubbles were generated to obtain a graphite oxide solution. The obtained graphite oxide solution was pickled with 1000ml of 12% hydrochloric acid, and the obtained graphene oxide was treated in an ultrasonic wave with a power of 400W for 4h, and then centrifuged, and 97g of potassium hydroxide and 164g of ammonia water were added. The reaction was stirred in a water bath for 1 hour, and the obtained precipitate was directly freeze-dried into powder, which was reacted in a 5000W microwave oven for 5 minutes, washed with water until neutral, and freeze-dried to obtain reduced graphene oxide powder.

Claims (10)

1. a one-pot method prepares a method for reducing graphene oxide, comprising oxidation reaction, reduction reaction and microwave activation, is characterized in that, specifically comprises the following steps: (1) Oxidation reaction: at room temperature, a strong oxidant is added to a strong acid solution containing graphite to obtain graphite oxide after oxidation, and water is added to quench the reaction to obtain a graphene oxide slurry through pickling, ultrasonication and centrifugation; (2) reduction reaction: adding a strong base compound to the graphene oxide slurry to carry out a reduction reaction, and obtaining an alkaline reduced graphene oxide suspension after the reaction is completed; (3) Microwave activation: after drying the reduced graphene oxide suspension, it is activated by microwave, washed with water until neutral and free of impurities, and then dried to obtain reduced graphene oxide powder. 2. a kind of one-pot method according to claim 1 prepares the method for reduced graphene oxide, it is characterized in that, in described step 1, described room temperature is 10～40 ℃, and the time of described oxidation reaction is 0.5～40 ℃ 48 hours. 3. a kind of one-pot method according to claim 1 prepares the method for reduced graphene oxide, it is characterized in that, in described step 1, described strong oxidant is potassium permanganate, potassium dichromate or potassium ferrate A combination of one or more of the above, the weight ratio of the strong oxidant to the graphite is 1 to 6:1. 4. the method for preparing reduced graphene oxide by a kind of one-pot method according to claim 1, is characterized in that, in described step 1, the power of ultrasonic is 10～500 W, and ultrasonic time is 30～300 min. 5. a kind of one-pot method according to claim 1 prepares the method for reduced graphene oxide, it is characterized in that, in described step 1, the acid that pickling adopts is the hydrochloric acid that concentration is 5～20%. 6. the method for preparing reduced graphene oxide by a one-pot method according to claim 1, is characterized in that, in described step 2, described reduction reaction temperature is 40～180 ℃, and the reaction times is 0.5～24 h . 7. a kind of one-pot method according to claim 1 prepares the method for reduced graphene oxide, it is characterized in that, in described step 2, described strong base compound is potassium hydroxide, sodium hydroxide or ammoniacal liquor One or more combinations, the add-on of strong alkali>the amount of acid neutralization in the graphene oxide slurry, after the acid is completely neutralized, continue to add strong alkali to make the pH of the alkali reduction graphene oxide suspension ≥9. 8. a kind of one-pot method according to claim 1 prepares the method for reduced graphene oxide, it is characterized in that, in described step 3, described drying mode is any one in vacuum drying, freeze-drying or spray-drying mode or a combination of more than one. 9. a kind of one-pot method according to claim 1 prepares the method for reduced graphene oxide, it is characterized in that, in described step 3, described microwave activation power is 100～10000w, and the time of microwave treatment is 0.5～10000w 300 minutes. 10. The method for preparing reduced graphene oxide by a one-pot method according to claim 1, wherein in the steps 1-3, the water is deionized water or ultrapure water.

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