CN110551994B

CN110551994B - δ-MnO2Synthesis method of nanosheet array

Info

Publication number: CN110551994B
Application number: CN201810556695.XA
Authority: CN
Inventors: 林宝伟; 夏晖; 房灵哲; 徐璟
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2018-06-01
Filing date: 2018-06-01
Publication date: 2021-09-28
Anticipated expiration: 2038-06-01
Also published as: CN110551994A

Abstract

The invention discloses delta-MnO₂A synthesis method of a nano-sheet array. Said method is in accordance with KMnO₄The molar ratio of KF to KF is 1: 2-6, first KMnO₄Mixing the solution with KF solution, and diluting with diluted H₂SO₄Adjusting the pH value to 1-3, adding a substrate material, carrying out hydrothermal reaction at 100-140 ℃, washing after the reaction is finished, and drying to obtain delta-MnO₂A nanosheet array. The invention adopts a one-step hydrothermal method to prepare the ultrathin array material without agglomeration, perfect crystallization, high purity and controllable morphology, and has simple process and low energy consumption. Prepared nanosheet array morphology delta-MnO₂The material grows on the substrate uniformly, the shape is uniform, agglomeration does not exist, the material can be directly used as electrodes of various electronic devices in later-stage application, the reduction of the specific surface area of the nano material and the reduction of the electrochemical performance caused by the use of an adhesive, a conductive agent and the like are avoided, meanwhile, the contact surface of the material can be effectively increased through the nano sheet array structure, and the material utilization rate is improved.

Description

δ-MnO2Synthesis method of nanosheet array

Technical Field

The invention belongs to the technical field of nano material preparation, and relates to delta-MnO₂In particular to delta-MnO₂A synthesis method of a nano-sheet array.

Background

Transition metal oxides have received much attention in the fields of supercapacitors, ion batteries, photocatalysis, etc. due to their specific structures and properties. Wherein, MnO₂The method is especially researched due to the abundant minerals, low cost, simple synthetic method, stable performance and no pollution to the environment. MnO₂Having a plurality of different types of crystal structures of [ MnO ]₆]The octahedron basis, the O atoms are distributed on the top of the octahedron corners, and the Mn atoms are located in the center of the octahedron. The vertexes, edges or surfaces of the octahedrons are connected in different forms to form different crystal forms,common crystal forms include α, β, γ, δ, λ, and the like.

δ-MnO₂Is composed of [ MnO₆]The layer structure material formed by octahedron sharing edges belongs to typical embedded material. As electrode material, delta-MnO₂Can well accommodate the ion intercalation/deintercalation. But the performance of the material is greatly influenced by factors such as crystallinity, morphology, chemical composition, dimensionality and the like.

Existing MnO₂There are many synthetic methods, such as the sol-gel method (H; A synthetic method of hydro-thermal and sol-gel method of MnO)₂nanostructres; journal of Sol-Gel Science and Technology), solid phase reaction method (Yinsu Wu; structural and morphological evaluation of mesopolous alpha-MnO₂andβ-MnO₂materials synthesized via different routes through KMnO₄/H₂C₂O₄A reaction; materials Letters), electrodeposition method (Jana, S.K; enhanced of performance property of electrochemically disposed MnO₂thin films growth in acidic medium; chemical Physics Letters) and microwave-assisted methods (Xiong Zhang; microwave-assisted refold synthesis of MnO₂nanostructures and the hair application in supercapacitors; electrochimica) and the like. The methods all have defects, for example, the sol-gel method has more reaction factors which need to be regulated and controlled, including the concentration, the pH value, the calcining temperature, the calcining time and the like of the precursor solution, so that the crystal form and the appearance of the synthesized powder are difficult to control, and the agglomeration of the powder is easily caused in the calcining process; the product obtained by electrodeposition has poor crystallinity and low purity. MnO₂The method also has the problems of poor conductivity, agglomeration phenomenon and low material utilization rate.

Disclosure of Invention

The invention aims to provide delta-MnO₂A synthesis method of a nano-sheet array.

The technical scheme for realizing the purpose of the invention is as follows:

δ-MnO₂the synthesis method of the nanosheet array comprises the following steps:

according to KMnO₄The molar ratio of KF to KF is 1: 2 to 6, adding KMnO₄Mixing the solution with KF solution, and diluting with diluted H₂SO₄Adjusting the pH value to 1-3, adding a substrate material, carrying out hydrothermal reaction at 100-140 ℃, washing after the reaction is finished, and drying to obtain delta-MnO₂A nanosheet array.

Preferably, said KMnO₄The molar ratio of KF to KF is 1: 3 to 4.

Preferably, said dilute H₂SO₄The concentration of (A) is 1M, and the pH value is adjusted to 1-2.

Preferably, the substrate material can be stainless steel sheet, titanium sheet, nickel mesh, gold foil, platinum foil, and carbon material such as carbon fiber and carbon nanotube.

Preferably, the hydrothermal reaction is carried out in a high-pressure reaction kettle, and the volume of the mixed solution is 75-85% of the volume of the reaction kettle.

Preferably, the hydrothermal reaction temperature is 110-130 ℃, and the reaction time is 0.5-2 h.

Compared with the prior art, the invention has the following advantages:

the invention adopts a simple one-step hydrothermal method, has short synthesis time, low reaction energy consumption, simple process and controllable process, and the prepared nanosheet array morphology delta-MnO₂The material grows on the substrate uniformly, and the shape is uniform without agglomeration. In later-stage application, for example, the nano-sheet array structure can be used as an electrode material and can be directly used as an electrode of various electronic devices, the reduction of the specific surface area of a nano-material and the reduction of electrochemical performance caused by the use of an adhesive, a conductive agent and the like are avoided, meanwhile, the contact surface of the material can be effectively increased through the nano-sheet array structure, and the utilization rate of the material is improved.

Drawings

FIG. 1 is a delta-MnO prepared in example 2₂XRD pattern of nanosheet array.

FIG. 2 is a delta-MnO prepared in example 2₂High power SEM images of nanoplate arrays.

FIG. 3 is a delta-MnO prepared in example 2₂Low power SEM images of nanoplate arrays.

FIG. 4 shows MnO prepared in comparative example 1₂SEM image of (d).

FIG. 5 shows MnO prepared in comparative example 2₂SEM image of (d).

FIG. 6 shows MnO prepared in comparative example 3₂SEM image of (d).

Detailed Description

The present invention will be described in further detail with reference to the following examples and the accompanying drawings.

Example 1

According to KMnO₄The molar ratio of KF to KF is 1: 2, mixing 1mmol of KMnO₄And 2mmol KF in 20ml deionized water, mixing the two solutions, and dissolving in 1M H₂SO₄Adjusting pH to 1, adding 3cm by 3cm carbon cloth as substrate material, performing hydrothermal reaction at 100 deg.C for 0.5h, washing the product with deionized water after the reaction is finished, and oven drying at 60 deg.C to obtain delta-MnO₂A nanosheet array.

Example 2

According to KMnO₄The molar ratio of KF to KF is 1: 4, mixing 1mmol of KMnO₄And 4mmol KF in 20ml deionized water, mixing the two solutions, and dissolving in 1M H₂SO₄Adjusting pH to 1, adding 3cm by 3cm carbon cloth as substrate material, performing hydrothermal reaction at 120 deg.C for 0.5h, washing the product with deionized water after the reaction is finished, and oven drying at 60 deg.C to obtain delta-MnO₂A nanosheet array.

Example 3

According to KMnO₄The molar ratio of KF to KF is 1: 6, 1mmol of KMnO₄And 6mmol KF in 20ml deionized water, mixing the two solutions, and dissolving in 1M H₂SO₄Adjusting pH to 1, adding 3cm by 3cm carbon cloth as substrate material, performing hydrothermal reaction at 140 deg.C for 0.5h, washing the product with deionized water after the reaction is finished, and oven drying at 60 deg.C to obtain delta-MnO₂A nanosheet array.

Example 4

According to KMnO₄The molar ratio of KF to KF is 1: 4, mixing 1mmol of KMnO₄And 4mmol KF in 20ml deionized water, mixing the two solutions, and dissolving in 1M H₂SO₄RegulatingAdding 3cm by 3cm carbon cloth as a substrate material when the pH value is 2, carrying out hydrothermal reaction for 1h at 120 ℃, washing a product with deionized water after the reaction is finished, and drying in a 60 ℃ oven to obtain delta-MnO₂A nanosheet array.

Example 5

According to KMnO₄The molar ratio of KF to KF is 1: 4, mixing 1mmol of KMnO₄And 4mmol KF in 20ml deionized water, mixing the two solutions, and dissolving in 1M H₂SO₄Adjusting pH to 3, adding 3cm by 3cm carbon cloth as substrate material, performing hydrothermal reaction at 120 deg.C for 2h, washing the product with deionized water after the reaction is finished, and oven drying at 60 deg.C to obtain delta-MnO₂A nanosheet array.

As shown in figure 1, the delta-MnO with the nanosheet array morphology prepared by the preparation method of the invention₂The XRD pattern of (A) is completely consistent with the standard card No.80-1098 in the database, which shows that the crystal phase composition of the product is delta-MnO₂In addition, the peak type of the visible ray diffraction peak is sharp, and the peak intensity is higher, which indicates that the crystal form is well developed.

As shown in figures 2 and 3, the delta-MnO with the nanosheet array morphology prepared by the preparation method of the invention₂SEM picture of (1), can see delta-MnO₂The nano-film is in an array shape, and the array structure is formed by assembling nano-sheets.

Comparative example 1

This comparative example is essentially the same as example 2, except that KF is not added. As can be seen from a comparison of FIGS. 3 and 4, the product to which KF was added was in the form of a flake, while the product to which KF was not added was in the form of a rod, indicating that the presence of KF is an important factor in forming a flake-like structure.

Comparative example 2

This comparative example is essentially the same as example 2, except that KF is replaced with KCl. As can be seen from a comparison of fig. 3 and 5, the product to which KF was added was flaky, while the product to which KCl was substituted was prismatic, further illustrating that the presence of KF is an important factor in forming a flaky structure.

Comparative example 3

This comparative example is essentially the same as example 2, except that no H was added₂SO₄. From the pair of FIG. 3 and FIG. 6As can be seen, H is added₂SO₄The product of (a) is in the form of higher loading flakes without the addition of H₂SO₄The product of (A) has only a very thin layer on the substrate material, indicating that H₂SO₄Is an important factor for accelerating the reaction process.

Claims

1.δ-MnO₂The synthesis method of the nanosheet array is characterized by comprising the following steps:

according to KMnO₄The molar ratio of KF to KF is 1: 2 to 6, adding KMnO₄Mixing the solution with KF solution, and diluting with diluted H₂SO₄Adjusting the pH value to 1-3, adding a substrate material, carrying out hydrothermal reaction at 100-140 ℃, wherein the reaction time is 0.5-2 h, washing after the reaction is finished, and drying to obtain delta-MnO₂A nanosheet array.

2. The method of claim 1, wherein the KMnO is a KMnO₄The molar ratio of KF to KF is 1: 3 to 4.

3. The method of synthesis of claim 1, wherein the dilute H is₂SO₄The concentration of (A) is 1M, and the pH value is adjusted to 1-2.

4. The synthesis method of claim 1, wherein the substrate material is selected from stainless steel sheet, titanium sheet, nickel mesh, gold foil, platinum foil, carbon fiber or carbon nanotube.

5. The synthesis method according to claim 1, wherein the hydrothermal reaction is carried out in an autoclave, and the volume of the mixed solution is 75-85% of the volume of the autoclave.

6. The synthesis method of claim 1, wherein the hydrothermal reaction temperature is 110 ℃ to 130 ℃.