A method for constructing fe3c based on capacitive deionization phase transition and lattice strain regulation

Abstract

The application relates to a method for constructing Fe3C based on capacitive deionization phase transition and lattice strain regulation. The purpose of the application is to solve the problems of few active sites and easy accumulation of existing Fe3C, and provide a method for constructing Fe3C based on phase transition and lattice strain synergic regulation with high adsorption performance. Method: zeolite imidazole acid framework-8 precursors are prepared by taking dimethyl imidazole and zinc nitrate as raw materials, the precursors are calcined under nitrogen condition to obtain nitrogen-doped carbon, and then the nitrogen-doped carbon is further calcined after being immersed in an iron citrate solution, so that Fe3C based on phase transition and lattice strain synergic regulation is formed, thereby providing a method for constructing iron-based materials with excellent capacitive deionization performance.

Description

TECHNICAL FIELD

[0001] The application relates to a construction method for regulating Fe3C based on capacitive deionization phase transition and lattice strain. BACKGROUND

[0002] Universal industrial pollution and uneven distribution of fresh water resources lead to a growing demand for clean water. Therefore, it is of great significance to solve the problem of fresh water shortage and promote the development of efficient water purification technology. Compared with traditional seawater desalination technologies (such as reverse osmosis and distillation), capacitive deionization technology has many advantages. The technology is based on electric adsorption and does not require harsh conditions such as high pressure or high temperature. It can be powered by renewable electricity such as solar energy, wind energy and rechargeable batteries. Capacitive deionization technology is environmentally friendly because it does not emit secondary pollutants. However, due to insufficient salt adsorption capacity and poor long-term cycle stability, the large-scale practical application of capacitive deionization is greatly limited. Therefore, one of the focuses of the research of this technology is to develop efficient capacitive deionization electrode materials.

[0003] Iron carbide material has the ability to remove metals and emerging organic pollutants, has the characteristics of high specific surface area, strong redox capacity, can quickly remove various environmental pollutants, and expand the effective working pH range, and has certain potential in the field of capacitive deionization. However, the problems of easy accumulation and few active sites in the synthesis process need to be improved. Therefore, it is compounded with hollow porous nitrogen-doped carbon. Because it has a high specific surface area of polyhedral structure, it can effectively shorten the electron transport distance, reduce the charge transfer impedance, and prevent the formed iron carbide from stacking, which can improve the desalination capacity of the electrode material. At the same time, through the liquid nitrogen quenching method, the phase transition and lattice strain of iron carbide are caused, the binding energy of the electrode material and sodium ions is increased, and the transmission of sodium ions in the electrode material is promoted. SUMMARY

[0004] The purpose of the present application is to overcome the problems of easy accumulation and few active sites of iron carbide in the synthesis process, and to provide a simple, novel and high-yield construction method.

[0005] The construction method for regulating Fe3C based on capacitive deionization phase transition and lattice strain of the present application is completed according to the following steps:

[0006] (1) Zinc nitrate and dimethyl imidazole are added to methanol, stirred, centrifuged and dried to obtain zeolite imidazole acid framework-8 precursor;

[0007] (2) 0.6 grams of the product in step (1) are placed in a tube furnace and calcined under N2 protection, and then naturally cooled to obtain nitrogen-doped carbon;

[0008] (3) Iron chloride, citric acid, sodium bicarbonate are dissolved in deionized water to form a ferric citrate solution A, and the product in step (2) is added to the solution A and stirred after heating, and then placed in a drying oven for drying;

[0009] (4) 0.3 grams of the dried product in step (3) is placed in a tube furnace and calcined under N2 protection, and then quenched by liquid nitrogen to obtain Fe3C material with synergistic regulation of phase change and lattice strain;

[0010] In step (1), the mass of zinc nitrate is 5-12 grams, the mass of dimethylimidazole is 5-12 grams, the volume of methanol is 100-500 milliliters, the stirring time is 1-5 hours, the stirring temperature is 30-50 degrees Celsius, the drying temperature is 50-80 degrees Celsius, and the drying time is 8-12 hours.

[0011] In step (2), the calcination temperature is 800-1200 degrees Celsius, and the calcination time is 1-4 hours.

[0012] In step (3), the iron chloride is 1-5 grams, the citric acid is 3-9 grams, the sodium bicarbonate is 4-11 grams, the volume of deionized water is 50-80 milliliters, the stirring time at room temperature is 30-50 minutes, the heating and stirring time is 2-4 hours, the heating and stirring temperature is 30-50 degrees Celsius, the drying temperature is 60-80 degrees Celsius, and the drying time is 10-12 hours.

[0013] In step (4), the calcination temperature is 600-800 degrees Celsius, and the calcination time is 10-30 minutes.

[0014] Compared with the prior art, the beneficial effects of the present application are: the present application constructs a construction method for Fe3C based on capacitive deionization phase change and lattice strain regulation, and the Fe3C material with synergistic regulation of phase change and lattice strain can be prepared in a short time during the construction process. In addition, the synthesis of the material does not require complex equipment, and the prepared material has excellent capacitive deionization performance. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Figure 1 is a transmission electron microscope image of Fe3C with synergistic regulation of phase change and lattice strain in Example 1;

[0016] Figure 2 Figure 2 is a powder X-ray diffraction spectrum of Fe3C with synergistic regulation of phase change and lattice strain in Example 1 and a control group;

[0017] Figure 3 Figure 3 is a desalination capacity performance graph of Fe3C with synergistic regulation of phase change and lattice strain in Example 1 and a control group. DETAILED DESCRIPTION

[0018] The technical scheme of the present application is not limited to the following specific embodiments, and the following specific embodiments are only used to illustrate the present application and are not limited to the technical scheme described in the examples. Those skilled in the art should understand that the present application can still be modified or replaced equivalently to achieve the same technical effect. As long as the use needs are met, it is within the protection scope of the present application.

[0019] The construction method of the high-performance Fe3C material with synergistic regulation of phase transition and lattice strain of the present embodiment is completed in the following steps:

[0020] (1) 10.7 grams of dimethylimidazole and 11.8 grams of zinc nitrate are added to 500 milliliters of methanol, stirred at 35 degrees Celsius for 4 hours to allow complete reaction, then washed with a methanol solution and centrifuged, and dried in a 60-degree Celsius drying oven for 12 hours to obtain zeolite imidazole acid framework-8;

[0021] (2) 0.6 grams of the product in step (1) is placed in a tube furnace and calcined at 920 degrees Celsius under N2 protection, and after natural cooling, nitrogen-doped carbon is obtained;

[0022] (3) 3 grams of iron chloride, 8 grams of citric acid, and 6 grams of sodium bicarbonate are dissolved in 50 milliliters of deionized water to form an iron citrate solution, and stirred at room temperature for 30 minutes. The product in step (2) is added to the iron citrate solution and heated and stirred for impregnation. The heating temperature is 40 degrees Celsius, and the heating and stirring time is 3 hours. Then it is placed in a 60-degree Celsius drying oven for drying for 12 hours;

[0023] (4) 0.3 grams of the dried material in step (3) is placed in a tube furnace and calcined at 750 degrees Celsius under N2 protection, and then quenched to obtain the Fe3C material with synergistic regulation of phase transition and lattice strain.

[0024] The present application will be further described below in conjunction with the drawings and examples:

[0025] Figure 1 The transmission electron microscope image of the Fe3C with synergistic regulation of phase transition and lattice strain of Example 1. After pyrolysis and quenching treatment, the hollow / multi-hollow structure skeleton of the Fe3C material with synergistic regulation of phase transition and lattice strain is well preserved and no structural collapse occurs.

[0026] Figure 2X-ray diffraction patterns of phase transformation and lattice strain synergistically regulated Fe3C of Example 1 and control group powders. As the nitrogen quenching temperature increases (from 150 degrees Celsius to 250 degrees Celsius), the Fe3C (Synthetic PDF #97-009-9032) phase transforms into the Fe3C (Iron Carbide PDF #97-016-7667) phase. In addition, compared with the Fe3C / NC-250 crystal phase, Fe3C / NC-X (X = 350 degrees Celsius to 750 degrees Celsius) is more strongly stressed during quenching, and the peak shifts to a small angle.

[0027] Figure 3 Desalination capacity performance chart of phase transformation and lattice strain synergistically regulated Fe3C of Example 1 and control group. The electrode adsorption capacity of the final product is higher than that of other control groups.

Claims

1. A method for constructing Fe3C based on capacitive deionization phase transition and lattice strain regulation, the method comprising the following steps: (1) Add zinc nitrate and dimethylimidazole to methanol, stir, centrifuge and dry to obtain zeolite imidazole acid framework-8 precursor; (2) Place 0.6 g of the product from step (1) in a tube furnace and calcine it under N2 protection conditions. After natural cooling, nitrogen-doped carbon is obtained. (3) Dissolve ferric chloride, citric acid and sodium bicarbonate in deionized water and stir at room temperature to form ferric citrate solution A. Add the product from step (2) to solution A, heat and stir, and then put it in a drying oven to dry. (4) Place 0.3 g of the dried material from step (3) in a tube furnace, calcine it under N2 protection, and then quench it with liquid nitrogen to obtain Fe3C material with phase change and lattice strain synergistic regulation.

2. The method for constructing Fe3C based on capacitive deionization phase transition and lattice strain regulation according to claim 1, characterized in that: In step (1), the mass of zinc nitrate is 5-12 grams, the mass of dimethylimidazole is 5-12 grams, the volume of methanol is 100-500 ml, the stirring time is 1-5 hours, the stirring temperature is 30-50 degrees Celsius, the drying temperature is 50-80 degrees Celsius, and the drying time is 8-12 hours.

3. The method for constructing Fe3C based on capacitive deionization phase transition and lattice strain regulation according to claim 1, characterized in that: In step (2), the calcination temperature is 800-1200 degrees Celsius and the calcination time is 1-4 hours.

4. The method for constructing Fe3C based on capacitive deionization phase transition and lattice strain regulation according to claim 1, characterized in that: In step (3), the amount of ferric chloride is 1-5 grams, citric acid is 3-9 grams, sodium bicarbonate is 4-11 grams, the volume of deionized water is 50-80 ml, the stirring time at room temperature is 30-50 minutes, the heating and stirring time is 2-4 hours, the heating and stirring temperature is 30-50 degrees Celsius, the drying temperature is 60-80 degrees Celsius, and the drying time is 10-12 hours.

5. The method for constructing Fe3C based on capacitive deionization phase transition and lattice strain regulation according to claim 1, characterized in that: In step (4), the calcination temperature is 600-800 degrees Celsius and the calcination time is 10-30 minutes.

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