CN104627995A - Bubble graphene material and preparation method thereof - Google Patents

Abstract

The invention provides a foam graphene material and a preparation method thereof. Dissolve oxalic acid in the graphene oxide dispersion at a weight ratio of 0.01 to 1:100; dry the resulting mixture; keep at 200°C for 5 to 30 minutes under a protective gas atmosphere, and then continue to heat up to 400 to 1000°C , and keep it for 0.5~5h; at 100~200°C, use hydrazine hydrate or hydroiodic acid as reducing agent for steam reduction for 1~2h. The bubble-shaped graphene nanomaterial of the present invention not only has the excellent electrical conductivity and thermal conductivity of graphene, but also improves the specific surface area of graphene. As an electrode material, the bubbles of the bubble graphene material become The small electrolyte storage pool significantly shortens the diffusion distance of the electrolyte, thereby increasing its electrochemical capacity. At the same time, the preparation process of the material is simple, the cost is low, and it can be mass-produced.

Description

Bubble graphene material and preparation method thereof

technical field

What the present invention relates to is a kind of graphene, and the present invention also relates to a kind of preparation method of graphene, specifically a kind of bubble graphene and preparation method thereof.

Background technique

Graphene is a two-dimensional single-molecular layer carbon material, which has a super high theoretical specific surface area (2630m ² /g), excellent mechanical strength, good flexibility, high electrical conductivity and excellent chemical stability, etc., causing It has attracted extensive attention from researchers at home and abroad (Novoselov K S, Geim A K, Morozov S V, et al. Science, 2004, 306:666; Yan J, WangQ, Wei T, et al. Advanced Energy Materials, 2014, 4: 1300816; Yang X, Cheng C, Wang Y, et al. Science, 2013, 341:534).

Compared with graphene crystals with complete structures, artificially constructing nanoscale structures on the surface of graphene sp2 hybridized carbon layers can prepare special graphene functional materials with special functions. For example, etching holes on the surface of graphene can prepare porous materials. Graphene, this material has very good application prospects in the fields of adsorption, catalysis and energy storage materials (Ning G, Xu C, Hao L, et al. Carbon, 2013, 51:390; Celebi K, Buchheim J, Wyss R M , et al. Science, 2014, 344:289; Han S, Wu D, Li S, et al.;. Adv Mater, 2014, 26:849). Artificially creating wrinkles on the surface of graphene can significantly increase the surface utilization of graphene, thereby improving its electrochemical energy storage performance. For example, Yan J et al. prepared wrinkled graphene by a huge temperature difference method of sudden heating and cooling, that is, after the dried graphene oxide was treated at 800-1000°C for 1-3 minutes, it was quickly put into low-temperature liquid nitrogen, and through the severe temperature difference Compared with the graphene prepared by traditional hydrazine hydrate reduction method, the specific surface area and specific capacitance of the material have been significantly improved (Yan J, Liu J, Fan Z, Wei T, Zhang L, Carbon, 2012, 50:2179). In summary, the microstructure design of the surface of graphene sheets can endow the material with special properties and functions, and expand the application fields of graphene.

Due to its excellent electrical conductivity and high specific surface area, electrode materials are the main application fields of graphene materials in the future. As mentioned above, the aggregation of graphene can be suppressed by creating holes and defects on the surface of graphene, thereby improving its surface utilization. thereby increasing its capacity. During the charging and discharging process of electrode materials, the diffusion rate of electrolyte ions inside the material is very important. The faster the diffusion rate of electrolyte ions inside the material, the higher the capacity of the electrode material. If the micro-electrolyte storage space can be designed inside the material while inhibiting the aggregation of graphene, the diffusion rate of electrolyte ions can be significantly shortened, thereby improving the electrochemical capacity of the material.

Contents of the invention

The object of the present invention is to provide a kind of bubble graphene material with larger specific surface area, excellent electrical conductivity and thermal conductivity. The object of the present invention is also to provide a method for preparing a bubble graphene material with simple process, low cost and large-scale production.

The foamed graphene material of the present invention is: protruding bubbles are evenly distributed on the two-dimensional plane of the graphene, and the diameter of the protruding bubbles is 50-500 nm.

The preparation method of bubble graphene material of the present invention is:

Dissolve oxalic acid in the graphene oxide dispersion at a weight ratio of 0.01 to 1:100; dry the resulting mixture; keep at 200°C for 5 to 30 minutes under a protective gas atmosphere, and then continue to heat up to 400 to 1000°C , and keep it for 0.5~5h; at 100~200°C, use hydrazine hydrate or hydroiodic acid as reducing agent for steam reduction for 1~2h.

The preparation method of bubble graphene material of the present invention can also comprise:

1. The drying temperature is 30-100° C., and the drying time is 2-48 hours.

2. The heating rate of the heating is 0.1-10° C./min.

3. The concentration of the graphene oxide dispersion is 0.1-5 mg/mL.

4. The protective gas is selected from at least one of nitrogen, argon or helium, and the flow rate of the protective gas is 50-500 mL/min.

Compared with ordinary graphene materials, the bubble-shaped graphene nanomaterial provided by the present invention not only has the excellent electrical conductivity and thermal conductivity of graphene, but also avoids graphene sheets due to the existence of graphene sheet bubbles. The agglomeration of layers improves the specific surface area of graphene, etc., so it has better performance than ordinary graphene in many fields such as energy storage, piezoelectric materials, and pressure-sensitive materials, especially as electrode materials, and the bubbling of bubbling graphene materials It becomes a small electrolyte storage pool inside the material, which significantly shortens the diffusion distance of the electrolyte, thereby increasing its electrochemical capacity. At the same time, the preparation process of the material is simple, the cost is low, and it can be mass-produced.

In the present invention, a small amount of oxalic acid is introduced into the surface of graphene oxide during the preparation process, and it is decomposed at low temperature in advance. The instantaneous pressure generated by the decomposition of oxalic acid can generate bubbling on the surface of graphene, and make the bubbling in the later treatment process. Bubbles continue to grow, and eventually a bubbling graphene material is obtained.

The bubbling graphene prepared by the present invention is observed by a scanning electron microscope, and the diameter of the bubbles is based on the statistical data given by the results of electron microscope photos.

Description of drawings

Fig. 1 is the scanning electron micrograph of the foamed graphene prepared in Example 4 of the present invention.

2 is a scanning electron micrograph of graphene prepared in Comparative Example 1 of the present invention.

Fig. 3 is a statistical table of bubble diameters of bubble graphene prepared in the embodiment of the present invention.

Fig. 4 is a comparison table of the electrochemical storage performance (the specific capacitance of the electrode material is measured by cyclic voltammetry) of the foamed graphene prepared in Example 4 of the present invention and the graphene prepared in Comparative Example 1.

Detailed ways

The preparation method of the foamed graphene provided by the present invention will be further described in detail with examples below.

Example 1

Firstly, 500mL of graphene oxide dispersion liquid is provided, the concentration is 0.1mg/mL, oxalic acid is added and stirred evenly, wherein the weight ratio of oxalic acid to graphene oxide is 0.01:100, and then it is dried at 30°C for 48h to prepare graphene oxide and oxalic acid Composite membrane, finally under the nitrogen atmosphere (flow rate 50mL/min), the resulting composite membrane of graphene oxide and oxalic acid was kept at 200°C for 5min, raised to 400°C at a rate of 0.1°C/min and kept for 5h, and then heated in hydrazine hydrate vapor Reduction at 100°C for 2 hours to obtain a foamed graphene material.

Example 2

First provide 500mL of graphene oxide dispersion with a concentration of 5mg/mL, add oxalic acid and stir evenly, wherein the weight ratio of oxalic acid to graphene oxide is 1:100, and then dry it at 100°C for 2h to prepare a compound of graphene oxide and oxalic acid Finally, under an argon atmosphere (flow rate 500mL/min), the resulting composite film of graphene oxide and oxalic acid was kept at 200°C for 30min, heated to 1000°C at a rate of 10°C/min, and kept for 0.5h, and then heated in hydrogen Reduction in iodic acid vapor at 200°C for 1 h to obtain a foamed graphene material.

Example 3

First, provide 500 mL of graphene oxide dispersion with a concentration of 2 mg/mL, add oxalic acid and stir evenly, wherein the weight ratio of oxalic acid to graphene oxide is 0.1:100, and then dry it at 80 ° C for 24 h to prepare graphene oxide and oxalic acid Composite membrane, finally in a helium atmosphere (flow rate 200mL/min), the resulting composite membrane of graphene oxide and oxalic acid was kept at 200°C for 10min, raised to 500°C at a rate of 5°C/min, and kept for 2h, and then in hydrogen Reduction in iodic acid vapor at 200°C for 1 h to obtain a foamed graphene material.

Example 4

First, provide 500 mL of graphene oxide dispersion with a concentration of 1 mg/mL, add oxalic acid and stir evenly, wherein the weight ratio of oxalic acid to graphite oxide is 0.1:100, and then dry it at 60 ° C for 30 h to prepare a composite of graphene oxide and oxalic acid Finally, under a nitrogen atmosphere (flow rate 200mL/min), the resulting composite film of graphene oxide and oxalic acid was kept at 200°C for 10min, raised to 400°C at a rate of 5°C/min, and kept for 2h, and then heated in hydrazine hydrate vapor Reduction at 200°C for 1 hour to obtain a foamed graphene material with a BET specific surface area of 612m ² /g.

Comparative Example 1

First, provide 500 mL of graphene oxide dispersion with a concentration of 1 mg/mL, then dry it at 60°C for 30 hours to prepare a graphene oxide film, and finally reduce it in hydrazine hydrate vapor at 200°C for 1 hour to obtain graphene, and its BET specific surface area was tested It is 437m ² /g.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims (10)

1. a blister grapheme material, is characterized in that: be uniform-distribution with protruding bubbling at the two dimensional surface of Graphene.

2. blister grapheme material according to claim 1, is characterized in that: the diameter of the bubbling of described projection is 50 ~ 500nm.

3. a preparation method for blister grapheme material according to claim 1, is characterized in that: according to weight ratio be the ratio of 0.01 ~ 1:100 by dissolving oxalic acid in graphene oxide dispersion; Gained mixture is dry; Under protective gas atmosphere, keep 5 ~ 30min in 200 DEG C, then continue to be warming up to 400 ~ 1000 DEG C, and keep 0.5 ~ 5h; Be the steam reduction 1 ~ 2h of reductive agent with hydrazine hydrate or hydroiodic acid HI at 100 ~ 200 DEG C.

4. the preparation method of blister grapheme material according to claim 3, is characterized in that: the temperature of described drying is 30 ~ 100 DEG C, and the dry time is 2 ~ 48h.

5. the preparation method of the blister grapheme material according to claim 3 or 4, is characterized in that: the temperature rise rate of described intensification is 0.1 ~ 10 DEG C/min.

6. the preparation method of the blister grapheme material according to claim 3 or 4, is characterized in that: the concentration of described graphene oxide dispersion is 0.1 ~ 5mg/mL.

7. the preparation method of blister grapheme material according to claim 5, is characterized in that: the concentration of described graphene oxide dispersion is 0.1 ~ 5mg/mL.

8. the preparation method of the blister grapheme material according to claim 3 or 4, is characterized in that: described protective gas is selected from least one in nitrogen, argon gas or helium, and the flow velocity of protective gas is 50 ~ 500mL/min.

9. the preparation method of blister grapheme material according to claim 5, is characterized in that: described protective gas is selected from least one in nitrogen, argon gas or helium, and the flow velocity of protective gas is 50 ~ 500mL/min.

10. the preparation method of blister grapheme material according to claim 6, is characterized in that: described protective gas is selected from least one in nitrogen, argon gas or helium, and the flow velocity of protective gas is 50 ~ 500mL/min.