CN111498839A - Ultrathin sheet layer reduced graphene oxide and synthesis method thereof - Google Patents

Ultrathin sheet layer reduced graphene oxide and synthesis method thereof Download PDF

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Publication number
CN111498839A
CN111498839A CN202010355450.8A CN202010355450A CN111498839A CN 111498839 A CN111498839 A CN 111498839A CN 202010355450 A CN202010355450 A CN 202010355450A CN 111498839 A CN111498839 A CN 111498839A
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graphene oxide
reduced graphene
temperature
ultrathin
graphite
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王晓君
刘治明
李海昌
杨磊
孙洪冉
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Qingdao University of Science and Technology
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Qingdao University of Science and Technology
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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
    • C01B32/182Graphene
    • C01B32/184Preparation
    • C01B32/19Preparation by exfoliation
    • C01B32/192Preparation by exfoliation starting from graphitic oxides
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00Structure or properties of graphene
    • C01B2204/20Graphene characterized by its properties
    • C01B2204/32Size or surface area

Abstract

The invention belongs to the technical field of electrode material preparation, and particularly relates to ultrathin sheet layer reduced graphene oxide and a synthesis method thereof. Performing low-temperature reaction, medium-temperature reaction and high-temperature reaction on natural graphite, sodium nitrate and potassium permanganate in sequence to obtain a graphite oxide dispersion liquid; filtering the dispersion liquid, washing with dilute hydrochloric acid, centrifuging, and drying to obtain graphite oxide; dispersing the obtained graphite oxide in water, performing ultrasonic treatment and centrifuging to prepare a graphene oxide dispersion; and finally, carrying out freeze drying and reduction to obtain the ultrathin sheet layer reduced graphene oxide. The ultrathin layer reduced graphene oxide provided by the invention has a higher specific surface area and a larger interlayer spacing, can ensure the smoothness of a lithium ion insertion/extraction channel, provides more exposed ion adsorption/desorption active sites, provides mutually connected three-dimensional open type nano sheets, provides a superior charge transfer channel for an external circuit, and is beneficial to improving the dynamic performance and the electrochemical performance of an electrode material.

Description

Ultrathin sheet layer reduced graphene oxide and synthesis method thereof
The technical field is as follows:
the invention belongs to the technical field of electrode material preparation, and particularly relates to ultrathin sheet layer reduced graphene oxide and a synthesis method thereof.
Background art:
due to strong van der waals force between graphene layers, single-layer graphene sheets are usually subjected to irreversible aggregation, and the utilization rate of the surface area of graphene in an electrode is reduced. Therefore, when building a functional graphene macrostructure, it is very critical to prevent the graphene sheets from re-aggregating in the macrostructure. At present, the aggregation of graphene nanoplatelets is generally prevented by means of template-assisted growth, electrochemical stripping and the like. These works have made great progress in the adsorption/desorption capacity of the supercapacitor positive electrode, but due to the narrow interlayer spacing of the reduced-redox graphene (rGO), the insertion/extraction electrochemical activity of lithium in the lithium ion battery negative electrode is far from meeting the application of the lithium ion battery, and slow ion transport kinetics are caused.
The invention content is as follows:
the technical problem to be solved by the invention is that the aggregation of the graphene nanosheets is prevented by means of template-assisted growth, electrochemical stripping and the like at present; these works have made great progress in the adsorption/desorption capacity of the supercapacitor positive electrode, but due to the narrow interlayer spacing of the reduced-redox graphene (rGO), the insertion/extraction electrochemical activity of lithium in the lithium ion battery negative electrode is far from meeting the application of the lithium ion battery, and slow ion transport kinetics are caused.
In order to solve the problems, graphite powder is used as a raw material, and a ultrathin layer reduced graphene oxide is synthesized by utilizing a thermal expansion principle; the ultrathin layer reduced graphene oxide has a high specific surface area and a large interlayer spacing, the large interlayer spacing can ensure the smoothness of a lithium ion insertion/extraction channel, the large specific surface area and a large number of mesopores provide more exposed ion adsorption/desorption active sites, and three-dimensional open type nano sheets are connected with each other, so that a superior charge transfer channel is provided for an external circuit, the dynamic performance of an electrode material is improved, and the electrochemical performance of the electrode material is improved.
In order to achieve the purpose, the invention is realized by the following technical scheme: a synthesis method of ultrathin flake layer reduced graphene oxide comprises the steps of sequentially carrying out low-temperature reaction, medium-temperature reaction and high-temperature reaction on natural graphite, sodium nitrate and potassium permanganate to obtain a graphite oxide dispersion liquid; filtering the dispersion liquid, washing with dilute hydrochloric acid, centrifuging, and drying to obtain graphite oxide; dispersing the obtained graphite oxide in water, performing ultrasonic treatment and centrifuging to prepare a graphene oxide dispersion; and then carrying out freeze drying to obtain graphene oxide foam, and finally carrying out high-temperature rapid reduction to obtain ultrathin sheet layer reduced graphene oxide.
Further, the low-temperature reaction is that at room temperature, 2g of granular natural graphite with the particle size of 30 micrometers and 1g of sodium nitrate are added into a 250m L three-neck flask to be cooled to 0 ℃, 50m L g of concentrated sulfuric acid is slowly added into the three-neck flask to be fully stirred for 30min, the temperature of a reaction system is kept to be not higher than 5 ℃, then 0.3g of potassium permanganate is added into the three-neck flask to be fully stirred for 30min, the temperature of the reaction system is kept to be not higher than 10 ℃, and within 1h, 7g of potassium permanganate is added into the three-neck flask in 3 batches, and the temperature of the reaction system is kept to be not higher than 20 ℃.
Further, the medium-temperature reaction is a low-temperature reaction, the ice bath is removed, the reaction system is heated to 35+3 ℃ by using the water bath, and the mixture is fully stirred for 2 hours to obtain brown suspension.
Further, the high temperature reaction is that 90m L water is slowly dripped into brown suspension, the temperature of the system is suddenly increased to 90 ℃ with a large amount of gas generated, the diluted suspension reacts for 15min at the temperature, and then 30 percent of H with the volume of 7m L is added into the suspension2O2And mixed with ultrapure water at 55m L and 45 ℃ to obtain a bright yellow graphite oxide dispersion.
Further, filtering the bright yellow graphite oxide dispersion liquid while the bright yellow graphite oxide dispersion liquid is hot to obtain a yellow brown filter cake, washing the filter cake with dilute hydrochloric acid of 150m L, the concentration of which is 3 percent and the temperature of which is 45 ℃ for 3 times, dispersing the filter cake into 600m L water, then centrifuging the filter cake at 4000rpm for 20min to obtain gel-like graphite oxide, transferring the gel-like graphite oxide to a vacuum drying oven of 40 ℃ to obtain graphite oxide after drying the gel-like graphite oxide for 24 h.
Further, dispersing the primarily generated graphite oxide in ultrapure water to form brown suspension, removing residual acid and salt through dialysis, dispersing the purified graphite oxide suspension in water to form tawny dispersion liquid with different concentrations (0.01mg/m L-1 mg/m L), stripping the graphite oxide for 30min by utilizing ultrasound (200W, 80%), centrifuging the obtained brown dispersion liquid (3000rpm, 30min), transferring the graphite oxide which is not stripped, taking supernatant, and freeze-drying to obtain graphene powder.
Further, Graphene Oxide (GO) dispersion (1.0mg/m L) is prepared, 10mg of graphene oxide powder is added into 10ml of water, and ultrasonic dispersion is carried out to obtain a Graphene Oxide (GO) dispersion water solution (1.0mg/m L).
Further, the suspension is transferred to a stainless steel culture dish, immersed in liquid nitrogen for freezing, and then vacuum-dried on a low-temperature vacuum dryer to obtain graphene oxide foam.
Further, reducing the graphene oxide foam at 800 ℃ in a nitrogen atmosphere, wherein the highest heating rate is 30 ℃/min, and synthesizing the reduced graphene oxide with the ultrathin sheet layer. In this step, due to thermal expansion and cold contraction, the graphene oxide sheets stacked on each other are separated and reduced under the impact of gas, and ultrathin sheet layers of reduced graphene oxide are formed.
The ultrathin flake layer reduced graphene oxide prepared by the method is mutually connected three-dimensional open type nano flakes and has a high specific surface area (2116 m)2g-1) And a larger interlayer spacing (0.39 nm). The larger interlayer space can ensure the smoothness of a lithium ion insertion/extraction channel, the larger specific surface area and a large number of mesopores provide more exposed ion adsorption/desorption active sites, and the three-dimensional open type nano sheets which are connected with each other provide a superior charge transfer channel for an external circuit, are favorable for improving the dynamic performance of an electrode material,thereby improving the electrochemical performance of the electrode material.
The invention has the beneficial effects that:
the ultrathin sheet layer reduced graphene oxide has wide lithium extension interlayer space, can provide a larger specific surface area for ion adsorption, can also provide an open and smooth ion insertion channel and three-dimensional open type nano sheets which are mutually connected, provides a superior charge transfer channel for an external circuit, and is beneficial to improving the dynamic performance of an electrode material, thereby improving the electrochemical performance of the electrode material.
Drawings
FIG. 1 is a composite scanning electron microscope picture I of the present invention;
FIG. 2 is a drawing of an ultrathin lamellar graphene photomicrograph
Fig. 3 is an ultra-thin graphene projection electron microscope.
The specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
a synthesis method of ultrathin sheet layer reduced graphene oxide comprises the following steps:
(1) at room temperature, 2g of granular natural graphite with the particle size of 30 mu m and 1g of sodium nitrate are added into a 250m L-mouth bottle to be cooled to 0 ℃, 50m L g of concentrated sulfuric acid is slowly added into the three-mouth bottle to be fully stirred for 30min, the temperature of a reaction system is kept to be not higher than 5 ℃, 0.3g of potassium permanganate is added into the three-mouth bottle to be fully stirred for 30min, the temperature of the reaction system is kept to be not higher than 10 ℃, 7g of potassium permanganate is added into the three-mouth bottle in 3 batches within 1h, the temperature of the reaction system is kept to be not higher than 20 ℃, and the low-temperature reaction is carried out at the stage.
(2) The ice bath was removed and the reaction was heated to 35+3 ℃ with a water bath and stirred well for 2h to give a brown suspension, which was a medium temperature reaction.
(3) 90m of L water were slowly added dropwise to the brown suspension, the temperature of the system was suddenly increased to 90 ℃ with considerable gas formation, and the diluted suspension was reacted at this temperature for 15min, this stage being carried out at elevated temperature.
(4) Adding H to the suspension2O2(30%, 7m L) and ultrapure water (55m L, 45 ℃ C.), and a bright yellow graphite oxide dispersion was obtained.
(5) And (3) filtering the suspension while the suspension is hot to obtain a yellow brown filter cake, washing the filter cake for 3 times by using 150m L diluted hydrochloric acid (3 percent at 45 ℃), dispersing the filter cake in 600m L water, centrifuging (4000rpm for 20min) to separate gelatinous graphite oxide, transferring the gelatinous graphite oxide to a vacuum drying oven at 40 ℃, and drying for 24h to obtain the graphite oxide.
(6) Dispersing the primarily generated graphite oxide in ultrapure water to form brown suspension, removing residual acid and salt through dialysis, dispersing the purified graphite oxide suspension in water to form tawny dispersion liquid with different concentrations (0.01mg/m L-1 mg/m L), separating the graphite oxide by using ultrasound (200W, 80%) for 30min, centrifuging (3000rpm, 30min) the obtained brown dispersion liquid to transfer the graphite oxide which is not separated, and taking supernatant to freeze and dry to obtain graphene oxide powder.
(7) Preparing Graphene Oxide (GO) dispersion (1.0mg/m L), adding 10mg of graphene oxide powder into 10ml of water, and performing ultrasonic dispersion to obtain a Graphene Oxide (GO) dispersion aqueous solution (1.0mg/m L).
(8) Transferring the suspension into a stainless steel culture dish, immersing the stainless steel culture dish into liquid nitrogen, and carrying out freeze drying to obtain graphene oxide foam; and then reducing the graphene oxide foam at 800 ℃ in a nitrogen atmosphere, wherein the highest heating rate is 30 ℃/min.
(9) In the above process, reduced graphene oxide having a ultrathin layer is synthesized.
The ultrathin lamellar reduced graphene oxide synthesized by the method is three-dimensional open type nanometer flake with 2116m, as shown in figures 1-32g-1Ultra high specific surface area and 0.3A larger interlayer spacing of 9 nm.

Claims (10)

1. A synthesis method of ultrathin sheet layer reduced graphene oxide is characterized by comprising the following steps: performing low-temperature reaction, medium-temperature reaction and high-temperature reaction on natural graphite, sodium nitrate and potassium permanganate in sequence to obtain a graphite oxide dispersion liquid; filtering the dispersion liquid, washing with dilute hydrochloric acid, centrifuging, and drying to obtain graphite oxide; dispersing the obtained graphite oxide in water, performing ultrasonic treatment and centrifuging to prepare a graphene oxide dispersion; and then carrying out freeze drying to obtain graphene oxide foam, and finally carrying out high-temperature rapid reduction to obtain ultrathin sheet layer reduced graphene oxide.
2. The method for synthesizing ultrathin lamellar reduced graphene oxide according to claim 1, wherein the low-temperature reaction is carried out by adding 2g of granular natural graphite with the particle size of 30 μm and 1g of sodium nitrate into a 250m L three-necked bottle at room temperature, cooling to 0 ℃, slowly adding 50m L g of concentrated sulfuric acid into the three-necked bottle, fully stirring for 30min while keeping the temperature of the reaction system at no more than 5 ℃, adding 0.3g of potassium permanganate into the three-necked bottle, fully stirring for 30min while keeping the temperature of the reaction system at no more than 10 ℃, adding 7g of potassium permanganate into the three-necked bottle in 3 batches within 1h, and keeping the temperature of the reaction system at no more than 20 ℃.
3. The method of synthesizing ultrathin lamellar reduced graphene oxide according to claim 1, characterized in that: the medium-temperature reaction is a low-temperature reaction, the ice bath is removed, the reaction system is heated to 35+3 ℃ by water bath, and the mixture is fully stirred for 2 hours to obtain brown suspension.
4. The method for synthesizing ultrathin lamellar reduced graphene oxide according to claim 1, wherein the high-temperature reaction is to slowly drop 90m L water into brown suspension, the temperature of the system is suddenly increased to 90 ℃ with a large amount of gas generated, the diluted suspension is reacted for 15min at the temperature, and then 30% of H with the volume of 7m L is added into the suspension2O2The resulting mixture was mixed with ultrapure water at 45 ℃ and 55m L to give a bright yellow colorA graphite oxide dispersion.
5. The method for synthesizing ultrathin laminated reduced graphene oxide as claimed in claim 1, wherein the method comprises filtering a dispersion of bright yellow graphite oxide while hot to obtain a yellow brown filter cake, washing the filter cake with 150m L, 3% diluted hydrochloric acid at 45 ℃ for 3 times, dispersing the filter cake in 600m L water, centrifuging at 4000rpm for 20min to obtain gel-like graphite oxide, transferring the gel-like graphite oxide to a 40 ℃ vacuum drying oven, and drying for 24h to obtain graphite oxide.
6. The method of synthesizing ultrathin lamellar reduced graphene oxide according to claim 1, characterized in that: dispersing the primarily generated graphite oxide in ultrapure water to form brown suspension, and removing residual acid and salt through dialysis; dispersing the purified graphite oxide suspension in water to form tawny dispersion liquid with different concentrations, stripping graphite oxide for 30min by utilizing ultrasound, centrifuging the obtained brown dispersion liquid, taking supernatant, and then freeze-drying to obtain graphene powder.
7. The method of synthesizing ultrathin lamellar reduced graphene oxide according to claim 1, characterized in that: and adding the graphene oxide powder into water, and performing ultrasonic dispersion to obtain a graphene oxide dispersion aqueous solution.
8. The method of synthesizing ultrathin lamellar reduced graphene oxide according to claim 1, characterized in that: and transferring the graphene oxide aqueous solution into a stainless steel culture dish, immersing the stainless steel culture dish into liquid nitrogen for freezing, and then performing low-temperature vacuum drying to obtain the graphene oxide foam.
9. The method of synthesizing ultrathin lamellar reduced graphene oxide according to claim 1, characterized in that: and (3) reducing the graphene oxide foam at 800 ℃ in a nitrogen atmosphere, wherein the heating rate is 30 ℃/min, and synthesizing the reduced graphene oxide with the ultrathin sheet layer.
10. A kind ofThe ultrathin lamellar reduced graphene oxide prepared by the synthesis method of claim 1, wherein the ultrathin lamellar reduced graphene oxide is characterized in that: is three-dimensional open nano-flake with 2116m2g-1Ultra high specific surface area and a large interlayer spacing of 0.39 nm.
CN202010355450.8A 2020-04-29 2020-04-29 Ultrathin sheet layer reduced graphene oxide and synthesis method thereof Pending CN111498839A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112479188A (en) * 2020-11-23 2021-03-12 陕西理工大学 Silicon-doped graphene aerogel and preparation method and application thereof
CN112768901A (en) * 2020-12-31 2021-05-07 西安工业大学 Three-dimensional graphene antenna and preparation method thereof
CN113194556A (en) * 2021-04-20 2021-07-30 广东温道百镒健康科技有限公司 Graphene radiation heating film and preparation method thereof
CN114100570A (en) * 2020-08-25 2022-03-01 华东理工大学 Preparation method and application of lithium ion selective adsorption membrane

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106967392A (en) * 2017-04-28 2017-07-21 哈尔滨赫兹新材料科技有限公司 The hot three-dimensional grapheme heat sink material of high-strength highly-conductive and its construction method
CN110436450A (en) * 2019-09-04 2019-11-12 广东石油化工学院 A method of removing graphite oxide prepares graphene oxide

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106967392A (en) * 2017-04-28 2017-07-21 哈尔滨赫兹新材料科技有限公司 The hot three-dimensional grapheme heat sink material of high-strength highly-conductive and its construction method
CN110436450A (en) * 2019-09-04 2019-11-12 广东石油化工学院 A method of removing graphite oxide prepares graphene oxide

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114100570A (en) * 2020-08-25 2022-03-01 华东理工大学 Preparation method and application of lithium ion selective adsorption membrane
CN114100570B (en) * 2020-08-25 2023-10-03 华东理工大学 Preparation method and application of lithium ion selective adsorption film
CN112479188A (en) * 2020-11-23 2021-03-12 陕西理工大学 Silicon-doped graphene aerogel and preparation method and application thereof
CN112479188B (en) * 2020-11-23 2023-02-28 陕西理工大学 Silicon-doped graphene aerogel and preparation method and application thereof
CN112768901A (en) * 2020-12-31 2021-05-07 西安工业大学 Three-dimensional graphene antenna and preparation method thereof
CN113194556A (en) * 2021-04-20 2021-07-30 广东温道百镒健康科技有限公司 Graphene radiation heating film and preparation method thereof

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