CN103887081A - Nanocomposite material of nitrogen doped with graphene/zinc ferrite and preparation method thereof - Google Patents

Abstract

The invention discloses a nitrogen-doped graphene/zinc ferrite nanocomposite material and its preparation. Ultrasonic disperse graphite oxide in ethylene glycol; dissolve zinc nitrate and ferric nitrate in water; add to the above graphene oxide solution and disperse it evenly; finally add urea to the above uniformly dispersed mixed solution , after dissolving, transferred to a hydrothermal kettle for solvothermal synthesis reaction, and the product was centrifugally washed and dried to obtain a nitrogen-doped graphene/zinc ferrite nanocomposite material. The present invention uses urea to reduce graphene oxide, and at the same time of reduction, nitrogen atoms are doped on the surface of graphene, and the doping of nitrogen atoms changes the chemical properties of graphene surface, making up for the existing surface of graphene prepared by chemical method At the same time, the alkalinity provided by urea makes zinc ferrite form on the surface of nitrogen-doped graphene, and zinc ferrite nanoparticles can further prevent the accumulation and agglomeration between graphene layers and improve the electrochemical performance of composite materials .

Description

A nitrogen-doped graphene/zinc ferrite nanocomposite material and its preparation

technical field

The invention belongs to the field of nanocomposite material preparation, in particular to a nitrogen-doped graphene/zinc ferrite nanocomposite material and its preparation.

Background technique

Graphene is a kind of carbon material. Since it came out in 2004, it has attracted widespread attention because of its unique photoelectric properties and structural properties. Graphene is widely used in energy storage devices (supercapacitors, lithium-ion batteries, fuel cells, etc.) due to its excellent electrical conductivity.

Graphene prepared by chemical methods is easy to pile up, and the difference in the degree of reduction will also affect the performance of graphene itself. In order to improve its performance, the preparation method and modification of graphene have become a research hotspot. At the same time, the introduction of heteroatoms can largely compensate for defects and improve performance. For example, Klaus Müllen et al. simultaneously doped nitrogen and boron on the surface of graphene by hydrothermal method (Three-Dimensional Nitrogen and Boron Co-doped Graphene for High-Performance All-Solid-State Supercapacitors.Advanced Materials2012,24(37) :5130-5135.); Chinese patents (CN103274393A, CN102760866A, CN103359708A, CN103359711A and CN102167310A, etc.) introduce nitrogen sources through different chemical methods, and prepare nitrogen-doped graphene. The required equipment is complex, the reaction conditions are harsh, and the yield is low; although the obtained nitrogen-doped graphene has improved its electrical conductivity compared with graphene, its electrochemical performance ( Such as specific capacitance) is far from meeting the requirements of practical applications.

Zinc ferrite in metal oxides has recently become a research hotspot. Its theoretical specific capacitance is as high as 1000mAh/g, but its attenuation is fast and its stability is poor. Therefore, its combination with carbon materials has become a research hotspot (Graphene anchored with ZnFe2O4 nanoparticles as a high- capacity anode material for lithium-ion batteries. Solid State Sciences 2013, 17, 67-71.), but its performance still needs to be improved. Nitrogen-doped graphene/zinc ferrite nanocomposites can make up for their respective defects and improve the overall performance of the material. At present, nitrogen-doped graphite/zinc ferrite binary nanocomposites have not been reported.

Contents of the invention

For the problem of existing preparation technology, the purpose of the present invention is to provide a kind of low cost, easy to operate preparation nitrogen-doped graphene/zinc ferrite nano-composite material and its method, this preparation method synthesis process is simple, is suitable for large Large-scale industrial production.

The technical solution to realize the object of the present invention is: a nitrogen-doped graphene/zinc ferrite nanocomposite material, the composite material is composed of matrix material nitrogen-doped graphene and zinc ferrite, wherein the matrix material nitrogen-doped The mass ratio of graphene to zinc ferrite is 1:3-1:10; the doping amount of nitrogen in the matrix material nitrogen-doped graphene is 1-2%.

A preparation method of nitrogen-doped graphene/zinc ferrite nanocomposite material, comprising the steps of:

The first step: Ultrasonic a certain amount of graphite oxide in ethylene glycol for a period of time to obtain a uniformly dispersed graphene oxide solution;

The second step: dissolve the weighed zinc nitrate and ferric nitrate in deionized water, and stir until they are completely dissolved;

The third step: pour the dissolved mixed metal salt solution into the graphene oxide solution obtained in the first step, and stir to make it evenly mixed;

The fourth step: add urea to the mixed system obtained in the third step, and stir again to make it evenly dispersed, wherein the mass ratio of urea to graphite oxide is 100:1-200:1;

Step 5: Transfer the uniformly mixed mixed solution to a hydrothermal kettle, and perform hydrothermal reaction at 120-200°C;

Step 6: Centrifuge the product of the fifth step, wash it with deionized water several times, and dry it to obtain a nitrogen-doped graphene/zinc ferrite nanocomposite material.

The ultrasonic dispersion time described in step 1 is 2-5 hours.

The molar ratio of ferric nitrate and zinc nitrate in step 2 is 2:1, and the stirring and dispersing time is 5-30 minutes.

The stirring and dispersing time described in Step 3 is 30-90 minutes.

The stirring time described in step 4 is 60-90 minutes.

The reaction time described in step five is 10-24h.

Compared with the prior art, the present invention has the following advantages: (1) The present invention is prepared by a solvothermal method, which requires low equipment, does not require high temperature, and has a simple synthesis process, which is conducive to low-cost large-scale production , and the reaction reagent is non-toxic and less polluting to the environment; (2) urea is used to reduce graphene oxide, and at the same time of reduction, nitrogen atoms are doped on the surface of graphene, and the doping of nitrogen atoms changes the surface of graphene The chemical properties make up for the surface defects of graphene prepared by chemical methods. At the same time, the alkalinity provided by urea makes zinc ferrite form on the surface of nitrogen-doped graphene, and zinc ferrite nanoparticles can further prevent the formation of graphene layers and layers. The accumulation and agglomeration between them improve the electrochemical performance of the composite material. Therefore, nitrogen-doped graphene and zinc ferrite are combined to give full play to the advantages of both and improve their respective defects, so as to obtain electrode materials with excellent electrochemical performance.

Description of drawings

Accompanying drawing 1 is the schematic flow chart of the preparation of nitrogen-doped graphene/zinc ferrite nanocomposite material of the present invention.

Figure 2 is the XPS spectrum (a) and XRD spectrum (b) of the structure characterization graph of the nitrogen-doped graphene/zinc ferrite nanocomposite obtained in Example 1 of the present invention.

Accompanying drawing 3 is the TEM photo of the morphology characterization diagram of the nitrogen-doped graphene/zinc ferrite nanocomposite material obtained in Example 1 of the present invention.

Accompanying drawing 4 is the XRD pattern (a) and the cyclic voltammetry performance test pattern (b) of the structural characterization diagram of the nitrogen-doped graphene/zinc ferrite nanocomposite obtained in Example 3 of the present invention.

Detailed ways

The preparation method of the nitrogen-doped graphene/zinc ferrite nanocomposite material with a mass ratio of 1:3 to 1:10 with a nitrogen doping amount of 1 to 2% will be further described below in conjunction with accompanying drawing 1 and specific examples. Detailed explanation.

Implementation example 1: the preparation method of a nitrogen-doped graphene/zinc ferrite nanocomposite material (the mass ratio of graphite oxide and zinc ferrite is 1:3) with a nitrogen content of 1%, comprising the following steps:

The first step is to sonicate graphite oxide with a content of 100mg in 50mL of ethylene glycol, and obtain a uniform graphene oxide solution after 3 hours of sonication;

In the second step, dissolve 1.0059g of ferric nitrate and 0.3703g of zinc nitrate in 10mL of deionized water and stir for 5min until they are completely dissolved;

In the third step, the mixed solution obtained above is poured into the graphene oxide solution obtained in the first step, and stirred for 30 minutes to make it evenly mixed;

In the fourth step, add 10 g of urea into the mixed system obtained in the third step, and stir again for 60 minutes to make it evenly dispersed;

Step 5: Transfer the uniformly mixed mixed solution to a hydrothermal kettle for solvothermal reaction, the reaction temperature is 100°C, and the reaction time is 24 hours;

Step 6: Centrifuge the product of the fifth step, wash it with deionized water several times, and dry it to obtain a nitrogen-doped graphene/zinc ferrite nanocomposite material.

As shown in Figure 2(a) XPS, the figure contains five elements of carbon, oxygen, nitrogen, iron and zinc, indicating the successful doping of nitrogen and the existence of zinc ferrite, and the content of nitrogen in it is 1%, the structural characterization diagram X-ray powder diffraction (XRD) is shown in Figure 2 (b), and the characteristic diffraction peaks can be seen in the figure, which can be attributed to zinc ferrite nanoparticles, so the prepared The product is a nitrogen-doped graphene/zinc ferrite nanocomposite.

Its TEM photograph is shown in accompanying drawing 3, can see that zinc ferrite nano-particle is evenly distributed on the surface of nitrogen-doped graphene from the figure, shows the successful preparation of binary nitrogen-doped graphene/zinc ferrite nanocomposite .

Implementation example 2: the preparation method of a nitrogen-doped graphene/zinc ferrite nanocomposite material (the mass ratio of graphite oxide to zinc ferrite is 1:5) with a nitrogen content of 1.5%, comprising the following steps:

The first step is to ultrasonicate 80 mg of graphite oxide in 40 mL of ethylene glycol for 2 hours to obtain a uniformly dispersed graphene oxide solution;

In the second step, dissolve 1.3411g ferric nitrate and 0.4938g zinc nitrate in 20mL deionized water and stir for 20min;

In the third step, the above-mentioned mixed solution obtained is poured into the graphene oxide solution obtained in the first step, and stirred for 60 minutes to make it evenly mixed;

In the fourth step, 15g of urea was added to the mixed system obtained in the third step, and stirred again for 75 minutes to make it evenly dispersed;

Step 5: Transfer the uniformly mixed mixed solution to a hydrothermal kettle for solvothermal reaction, the reaction temperature is 180°C, and the reaction time is 18 hours;

Step 6: Centrifuge the product of the fifth step, wash it with deionized water several times, and dry it to obtain a nitrogen-doped graphene/zinc ferrite nanocomposite material.

Implementation example 3: the preparation method of a nitrogen-doped graphene/zinc ferrite nanocomposite material (the mass ratio of graphite oxide to zinc ferrite is 1:10) with a nitrogen content of 2%, comprising the following steps:

The first step is to ultrasonicate 100 mg of graphite oxide in 40 mL of ethylene glycol for 5 hours to obtain a uniformly dispersed graphene oxide solution;

In the second step, dissolve 3.3529g ferric nitrate and 1.2344g zinc nitrate in 20mL deionized water and stir for 30min;

In the third step, the above-mentioned mixed solution is poured into the graphene oxide solution obtained in the first step, and stirred for 90 minutes to make it evenly mixed;

In the fourth step, 20 g of urea was added to the mixed system obtained in the third step, and stirred again for 90 minutes to make it uniformly dispersed;

Step 5: Transfer the uniformly mixed mixed solution to a hydrothermal kettle for hydrothermal reaction, the reaction temperature is 200°C, and the reaction time is 10 hours;

Step 6: Centrifuge the product of the fifth step, wash it with deionized water several times, and dry it to obtain a nitrogen-doped graphene/zinc ferrite nanocomposite material.

Structural characterization X-ray powder diffraction (XRD) is shown in Figure 4(a). There are obvious characteristic diffraction peaks in the figure, and the characteristic diffraction peaks can be attributed to zinc ferrite nanoparticles. When the hydrothermal temperature changes, It can be seen that the characteristic peaks of zinc ferrite have slight changes, which can prove that the obtained product is a nitrogen-doped graphene/zinc ferrite nanocomposite material. (b) Its electrochemical performance test chart, when the scan rate is 1mV/s, its specific capacitance is as high as 659F/g, which is greatly improved compared with single-component electrode materials, and its current density is 100mA /g, after 5000 cycles, the Coulombic efficiency has been maintained at about 100%, and the specific capacitance maintenance rate has been maintained at about 85%, which is greatly improved compared with the binary component without nitrogen doping.

Claims (8)

1. A nitrogen-doped graphene/zinc ferrite nanocomposite material is characterized in that said composite material is made up of matrix material nitrogen-doped graphene and zinc ferrite, wherein, matrix material nitrogen-doped graphene and ferric acid The mass ratio of zinc is 1:3-1:10; the doping amount of nitrogen in the base material nitrogen-doped graphene is 1-2%. 2. nitrogen-doped graphene/zinc ferrite nanocomposite material according to claim 1, is characterized in that described composite material is prepared by the following steps: The first step: ultrasonically disperse graphite oxide in ethylene glycol to obtain a uniformly dispersed graphene oxide solution; Step 2: Dissolve zinc nitrate and ferric nitrate in deionized water, and stir until they are completely dissolved; The third step: pour the dissolved mixed metal salt solution into the graphene oxide solution obtained in the first step, and stir to make it evenly mixed; The fourth step: add urea to the mixed system obtained in the third step, and stir again to make it evenly dispersed, wherein the mass ratio of urea to graphite oxide is 100:1-200:1; Step 5: Transfer the uniformly mixed mixed solution to a hydrothermal kettle, and perform hydrothermal reaction at 120-200°C; Step 6: Centrifuge the product of the fifth step, wash it with deionized water several times, and dry it to obtain a nitrogen-doped graphene/zinc ferrite nanocomposite material. 3. the preparation of a nitrogen-doped graphene/zinc ferrite nanocomposite is characterized in that comprising the steps: The first step: ultrasonically disperse graphite oxide in ethylene glycol to obtain a uniformly dispersed graphene oxide solution; Step 2: Dissolve zinc nitrate and ferric nitrate in deionized water, and stir until they are completely dissolved; The third step: pour the dissolved mixed metal salt solution into the graphene oxide solution obtained in the first step, and stir to make it evenly mixed; The fourth step: add urea to the mixed system obtained in the third step, and stir again to make it evenly dispersed, wherein the mass ratio of urea to graphite oxide is 100:1-200:1; Step 5: Transfer the uniformly mixed mixed solution to a hydrothermal kettle, and perform hydrothermal reaction at 120-200°C; Step 6: Centrifuge the product of the fifth step, wash it with deionized water several times, and dry it to obtain a nitrogen-doped graphene/zinc ferrite nanocomposite material. 4. The preparation of nitrogen-doped graphene/zinc ferrite nanocomposite material according to claim 3, characterized in that the ultrasonic dispersion time described in the first step is 2 to 5 hours. 5. the preparation of nitrogen-doped graphene/zinc ferrite nanocomposite material according to claim 3, it is characterized in that the mol ratio of ferric nitrate described in the second step and zinc nitrate is 2:1, stirring dispersion time 5 to 30 minutes. 6. The preparation of the nitrogen-doped graphene/zinc ferrite nanocomposite material according to claim 3, characterized in that the stirring and dispersing time described in the third step is 30 to 90 minutes. 7. The preparation of nitrogen-doped graphene/zinc ferrite nanocomposite material according to claim 3, characterized in that the stirring time described in the fourth step is 60-90min. 8. The preparation of nitrogen-doped graphene/zinc ferrite nanocomposite material according to claim 3, characterized in that the reaction time described in the fifth step is 10-24h.

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