阅读说明：本技术 一种以mof为前驱体的二硫化亚铁及其制备方法 (Ferrous disulfide taking MOF as precursor and preparation method thereof ) 是由 邱红 岳继礼 路遥 蒋鑫 施正旖 于 2020-04-29 设计创作，主要内容包括：本发明属于材料制备领域,具体涉及一种以MOF为前驱体的二硫化亚铁及其制备方法。二硫化亚铁的结构为MOF型,且在材料的表面有碳包覆层；所述制备方法的具体步骤如下：步骤(1)：将铁盐、碳源、沉淀剂和分散剂等溶于溶剂中,在烘箱中保温一定时间,得到Fe基前驱体；步骤(2)：将步骤(1)中得到的Fe基前驱体与羧酸按比例溶于溶剂中,在烘箱中保温,得到Fe-MOF前驱体；步骤(3)：将步骤(2)中得到的Fe-MOF前驱体和硫粉按比例在惰性气氛下进行煅烧处理,得到表面碳包覆的MOF型二硫化亚铁。本发明的方法能够调控前躯体的粒径和孔结构。本发明制备的FeS2应用于钠离子电池的负极材料中,有效提高了电池的循环寿命,具有良好的电化学性能。(The invention belongs to the field of material preparation, and particularly relates to ferrous disulfide taking MOF as a precursor and a preparation method thereof. The structure of the ferrous disulfide is MOF type, and a carbon coating layer is arranged on the surface of the material; the preparation method comprises the following specific steps: step (1): dissolving iron salt, a carbon source, a precipitator, a dispersing agent and the like into a solvent, and preserving the solution in an oven for a certain time to obtain a Fe-based precursor; step (2): dissolving the Fe-based precursor obtained in the step (1) and carboxylic acid in a solvent according to a ratio, and preserving heat in an oven to obtain a Fe-MOF precursor; and (3): and (3) calcining the Fe-MOF precursor and the sulfur powder obtained in the step (2) in an inert atmosphere according to a ratio to obtain the MOF ferrous disulfide with carbon-coated surface. The method of the invention can regulate and control the particle size and the pore structure of the precursor. The FeS2 prepared by the method is applied to the cathode material of the sodium-ion battery, so that the cycle life of the battery is effectively prolonged, and the battery has good electrochemical performance.)

1. The ferrous disulfide taking the MOF as a precursor is characterized in that the structure of the ferrous disulfide is MOF type, and a carbon coating layer is arranged on the surface of the material.

2. A method of preparing the ferrous disulfide of claim 1, comprising preparation of Fe-MOF precursor and high temperature sintering sulfidation; and adding a carbon source in the preparation of the MOF precursor, and separating out carbon in the carbon source in the subsequent high-temperature sintering and vulcanizing step to obtain the ferrous disulfide coated with carbon on the surface.

3. The method according to claim 2, characterized by the following specific steps:

step (1): dissolving iron salt, a carbon source, a precipitator, a dispersing agent and the like into a solvent, and preserving the solution in an oven for a certain time to obtain a Fe-based precursor;

step (2): dissolving the Fe-based precursor obtained in the step (1) and carboxylic acid in a solvent according to a ratio, and preserving heat in an oven to obtain a Fe-MOF precursor;

and (3): and (3) calcining the Fe-MOF precursor and the sulfur powder obtained in the step (2) in an inert atmosphere according to a ratio to obtain the MOF ferrous disulfide with carbon-coated surface.

4. The method according to claim 3, characterized in that step (1) is in particular: dissolving Fe, a carbon source and a precipitating agent in ferric salt in deionized water according to a molar ratio of 1: 1.5-2: 1.6-2, uniformly stirring, then adding a dispersing agent into the uniformly stirred solution, uniformly stirring and mixing, transferring the solution to a reaction kettle, preserving heat for 8-12h at 160-180 ℃ to obtain a black suspension, then centrifugally washing the obtained black suspension with deionized water and ethanol to obtain black powder, and drying for 8-12h at 60 ℃ in a vacuum oven to obtain an Fe-based precursor.

5. The method of claim 4, wherein the iron salt is one of ferric chloride hexahydrate and ferric nitrate nonahydrate.

6. The method of claim 4, wherein the carbon source is sodium citrate, the precipitating agent is urea, and the dispersing agent is PVP.

7. The method according to claim 3, characterized in that the step (2) is in particular: dissolving the Fe-based precursor and carboxylic acid obtained in the step (1) into DMF (dimethyl formamide) according to the mol ratio of Fe to carboxylic acid in iron salt of 2:1, transferring the prepared solution into a reaction kettle, preserving the heat for 16-20 h at 110-120 ℃, fully cleaning with deionized water and absolute ethyl alcohol, and drying in a vacuum oven at 150 ℃ for 8h to obtain orange MIL-101-Fe, namely the Fe-MOF precursor.

8. The method according to claim 7, characterized in that the molar weight ratio of the dispersant PVP (K60) to the iron of the iron salt is 1: 0.000005.

9. the process of claim 7, wherein the carboxylic acid is terephthalic acid.

10. The method according to claim 3, characterized in that the step (3) is in particular: mixing a Fe-MOF precursor and sulfur powder according to a mass ratio of 1: 3-5, putting the mixture into a tubular furnace, placing the uniformly mixed sample into a 500-doped solution at a temperature of 600 ℃ for heat preservation reaction for 8-12h under the protection of argon at a heating rate of 3-5 ℃/min, and cooling to room temperature after the reaction is finished to obtain the FeS with the surface coated with carbon₂@C。

Technical Field

The invention belongs to the field of material preparation, and particularly relates to ferrous disulfide taking MOF as a precursor and a preparation method thereof.

Background

Metal organic framework Materials (MOFs) generally refer to highly structured crystalline materials that are built up as a framework from organic groups, inorganic metal nodes or metal cluster secondary building units are used as connection points, and are coordinated and self-assembled under hydrothermal or solvothermal conditions. Other types of interactions, such as hydrogen bonding and van der waals forces, may also play a role in forming the three-dimensional structures of MOFs. Currently, many 20000 MOFs materials have been discovered by scientists. Because its structure is similar to that of zeolites, and the framework is relatively soft, it is also known as "soft zeolites".

The MOF material has an ultra-large specific surface area, is rich in pore channels and exposed active sites inside, is beneficial to charge accumulation, electrolyte infiltration and rapid ion movement, and can effectively improve the electrochemical performance of the material through the design of the MOF structure, so that the MOF material becomes a large direction for the application of the MOF material when being used in the electrochemical field. Since the Yaghi task group first defined the metal organic framework material in 1995, MOF materials have been rapidly developed and widely used in many fields such as lithium sulfur batteries, lithium ion batteries, adsorption, catalysis, and sensing, etc., for example, as a positive electrode material of lithium sulfur batteries, a positive electrode of lithium ion batteries, a negative electrode material, and an electrocatalyst for hydrogen evolution reaction and oxygen evolution reaction, etc. The applications of MOF materials and their derivatives to electrochemistry have been increasingly reported in recent years. The preparation approaches of the MOF material are many, and currently, hydrothermal/solvothermal synthesis, microwave synthesis, electrochemical synthesis, ultrasonic synthesis and the like are common.

Ferrous disulfide has an ultra-high theoretical specific capacity, but the poor conductivity of the material itself limits its development for electrode materials.

Disclosure of Invention

The invention aims to provide ferrous disulfide taking MOF as a precursor and a preparation method thereof.

The technical solution for realizing the purpose of the invention is as follows: the ferrous disulfide takes MOF as a precursor, the structure of the ferrous disulfide is MOF type, and a carbon coating layer is arranged on the surface of the material.

A method for preparing the ferrous disulfide comprises the steps of preparing a Fe-MOF precursor and sintering and vulcanizing at high temperature; and adding a carbon source in the preparation of the MOF precursor, and separating out carbon in the carbon source in the subsequent high-temperature sintering and vulcanizing step to obtain the ferrous disulfide coated with carbon on the surface.

The method comprises the following specific steps:

step (1): dissolving iron salt, a carbon source, a precipitator, a dispersing agent and the like into a solvent, and preserving the solution in an oven for a certain time to obtain a Fe-based precursor;

step (2): dissolving the Fe-based precursor obtained in the step (1) and carboxylic acid in a solvent according to a ratio, and preserving heat in an oven to obtain a Fe-MOF precursor;

and (3): and (3) calcining the Fe-MOF precursor and the sulfur powder obtained in the step (2) in an inert atmosphere according to a ratio to obtain the MOF ferrous disulfide with carbon-coated surface.

Further, the step (1) is specifically as follows: dissolving Fe, a carbon source and a precipitating agent in ferric salt in deionized water according to a molar ratio of 1: 1.5-2: 1.6-2, uniformly stirring, then adding a dispersing agent into the uniformly stirred solution, uniformly stirring and mixing, transferring the solution to a reaction kettle, preserving heat for 8-12h at 160-180 ℃ to obtain a black suspension, then centrifugally washing the obtained black suspension with deionized water and ethanol to obtain black powder, and drying for 8-12h at 60 ℃ in a vacuum oven to obtain an Fe-based precursor.

Further, the ferric salt is one of ferric chloride hexahydrate and ferric nitrate nonahydrate.

Further, the carbon source is sodium citrate, the precipitator is urea, and the dispersant is PVP.

Further, the step (2) is specifically as follows: dissolving the Fe-based precursor and carboxylic acid obtained in the step (1) into DMF (dimethyl formamide) according to the mol ratio of Fe to carboxylic acid in iron salt of 2:1, transferring the prepared solution into a reaction kettle, preserving the heat for 16-20 h at 110-120 ℃, fully cleaning with deionized water and absolute ethyl alcohol, and drying in a vacuum oven at 150 ℃ for 8h to obtain orange MIL-101-Fe, namely the Fe-MOF precursor.

Further, the molar weight ratio of the dispersant PVP (K60) to the iron in the iron salt is 1: 0.000005.

further, the carboxylic acid is terephthalic acid.

Further, the step (3) is specifically as follows: mixing a Fe-MOF precursor and sulfur powder according to a mass ratio of 1: 3-5, putting the mixture into a tubular furnace, placing the uniformly mixed sample into a 500-doped solution at a temperature of 600 ℃ for heat preservation reaction for 8-12h under the protection of argon at a heating rate of 3-5 ℃/min, and cooling to room temperature after the reaction is finished to obtain the FeS with the surface coated with carbon₂@C。

Compared with the prior art, the invention has the remarkable advantages that:

(1) according to the invention, through a simple-process low-cost water/solvothermal method, an iron-based MOF precursor is obtained firstly, and then sintering and vulcanizing at high temperature are carried out to obtain the FeS with the carbon-coated surface₂(ii) a The ion transmission distance can be shortened by taking the MOF as a template, and the problem that the original short plate with lower conductivity can be solved after the surface is coated with carbon is solved, so that the prepared ferrous disulfide is very suitable for being used as a negative electrode material of a sodium ion battery; can effectively prolong the cycle life of the battery, has good electrochemical performance, and is expected to be applied to the fields of electrochemical catalysis, energy conversion, energy storage and the like.

(2) FeS prepared by the water/solvothermal and solid-phase reaction method₂By adjusting the types and the quantity of the raw materials and the sintering temperature, the particle size of the material can be effectively regulated, and the sulfur content, the pore structure and the electrical conductivity can be regulated.

Drawings

FIG. 1 shows FeS in example 1₂Scanning Electron microscopy of @ C.

FIG. 2 shows FeS in example 1₂@ C and standard FeS₂X-ray diffraction contrast chart of (1).

FIG. 3 shows FeS in example 2₂Scanning Electron microscopy of @ C.

FIG. 4 shows FeS in example 3₂Scanning Electron microscopy of @ C.

FIG. 5 shows FeS in example 4₂Scanning Electron microscopy of @ C.

FIG. 6 shows FeS in example 5₂Scanning Electron microscopy of @ C.

FIG. 7 shows FeS in example 6₂Scanning Electron microscopy of @ C.

FIG. 8 shows FeS in example 1₂@ C is used as the specific capacity-cycle diagram of the negative electrode material of the sodium ion half-cell.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The invention aims to provide a preparation method of ferrous disulfide taking MOF as a template, which adopts low-cost raw materials, obtains an iron-based MOF precursor through a hydrothermal method, and obtains ferrous disulfide with uniform and controllable size after high-temperature heat treatment and vulcanization.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of ferrous disulfide taking MOF as a template comprises the following specific steps:

step 1: dissolving ferric salt, a carbon source and a precipitator into deionized water according to the molar ratio of Fe to the carbon source to the precipitator of 1: 1.5-2: 1.6-2, uniformly stirring, then adding a certain molar amount of a dispersing agent into the uniformly stirred solution, uniformly stirring and mixing, transferring the solution to a reaction kettle, and preserving heat at 160-180 ℃ for 12 hours. And then, centrifugally washing the obtained black suspension by using deionized water and ethanol to obtain black powder, and drying the black powder in a vacuum oven at 60 ℃ for 8-12h to obtain the iron-based precursor.

Step 2: and (2) dissolving the iron-based precursor and carboxylic acid obtained in the step (1) in DMF (dimethyl formamide) according to the molar ratio of iron to carboxylic acid of 2:1, transferring the prepared solution to a reaction kettle, preserving the temperature for 16-20 h at 110-120 ℃, fully cleaning with deionized water and absolute ethyl alcohol, and drying in a vacuum oven at 150 ℃ for 8h to obtain orange MIL-101-Fe.

And step 3: will be ahead ofMixing the precursor and sulfur powder according to a mass ratio of 1: 3-5, putting the mixture into a tube furnace, placing the uniformly mixed sample at 500-600 ℃ for heat preservation reaction for 8-12h under the protection of argon at a heating rate of 3-5 ℃/min, and cooling to room temperature after the reaction is finished to obtain FeS with the surface coated with carbon₂@C。

The ferric salt is selected from ferric chloride hexahydrate and ferric nitrate nonahydrate, the carbon source is sodium citrate, the precipitator is urea, and the dispersing agent is PVP.

The molar weight ratio of the dispersant PVP (K60) to the iron salt is 1: 0.000005.

the carboxylic acid is terephthalic acid.