A method for room-temperature rapid controllable preparation of three-dimensional porous carbon materials

Abstract

The application provides a method for rapidly and controllably preparing three-dimensional porous carbon materials at room temperature, which utilizes soluble inorganic salts as templates, selects organic carbon sources, and prepares three-dimensional porous carbon materials through room-temperature anti-solvent precipitation and one-step pyrolysis. The application has the advantages of simple process, good controllability, high repeatability, and easy morphology control, and can prepare three-dimensional hierarchical porous structure materials only by using a single template, and is suitable for large-scale industrial application.

Description

Technical Field

[0001] This invention relates to an industrial production technology for three-dimensional porous carbon (room temperature reverse solvent precipitation method). The prepared material can be applied to electrochemical energy storage and conversion, belonging to the fields of nanomaterial preparation technology and electrochemical energy conversion and storage applications. Background Technology

[0002] Three-dimensional porous carbon materials are widely used in electrochemical energy storage and conversion. Their porous nature facilitates electrolyte penetration and contact with electrode materials, resulting in high electrochemical activity. Furthermore, three-dimensional porous carbon materials also possess advantages such as large specific surface area, excellent electrical conductivity, good thermal conductivity, and high mechanical strength. Therefore, they can be applied in various fields, including lithium / sodium / potassium ion batteries, supercapacitors, lithium / zinc-air batteries, lithium / sodium-carbon dioxide batteries, lithium / sodium / potassium-sulfur batteries, lithium metal batteries, electrocatalytic hydrogen / oxygen evolution, and carbon dioxide reduction.

[0003] Currently, hydrothermal, solvothermal, sol-gel, and electrospinning techniques are the main methods for preparing three-dimensional porous carbon materials. However, these methods suffer from high production costs, complex synthesis processes, and low yields due to the high temperature and pressure conditions of hydrothermal and solvothermal processes, the additive requirements of sol-gel processes, and the unique characteristics of electrospinning, making them unsuitable for large-scale industrial applications. In contrast, spray drying and freeze-drying methods using soluble salt templates have solved the problem of low yields and reduced costs and process complexity to some extent. However, creating high and low temperature environments still inevitably leads to energy consumption and requires large-scale auxiliary equipment, and the synthesis process is lengthy. Furthermore, the above strategies require the blending of various types of template raw materials to construct hierarchical porous structures, further increasing costs and experimental complexity. These challenges restrict the large-scale industrial application of three-dimensional porous carbon materials in the electrochemical field. Therefore, developing efficient, inexpensive, high-yield, and environmentally friendly synthesis strategies for preparing three-dimensional porous carbon materials remains a challenge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a universal method for the efficient preparation of three-dimensional porous carbon materials at room temperature. This method boasts high yield, high efficiency, low raw material cost, and recyclable templates and solvents. The method is not only simple, highly controllable, and reproducible, but also allows for easy morphological control. It requires only a single template to prepare three-dimensional hierarchical porous materials, making it suitable for large-scale industrial applications. The technical solution of this invention to solve the above-mentioned technical problem is as follows:

[0005] A method for rapidly and controllably preparing three-dimensional porous carbon materials at room temperature is disclosed, which utilizes soluble inorganic salts as templates, selects organic carbon sources, and prepares three-dimensional porous carbon materials through room temperature antisolvent precipitation and one-step pyrolysis.

[0006] Furthermore, it includes the following steps:

[0007] (1) Select one or more soluble inorganic salts as salt templates, select one or more organic carbon sources, dissolve the organic carbon sources and salt templates in water to obtain mixed solution A;

[0008] (2) Select an antisolvent, pour the obtained mixed solution A into the antisolvent, filter and dry, and obtain white precursor powder labeled as B;

[0009] (3) The precursor powder B prepared by calcination under a reducing atmosphere is used to obtain the calcined product;

[0010] (4) Remove the soluble salt template to prepare a three-dimensional porous carbon material.

[0011] Furthermore, in step (1), the molar mass ratio of carbon atoms in the organic carbon source to the soluble salt template is 1:2 to 3:1.

[0012] Further, in step (1), the soluble inorganic salt template is sodium chloride (NaCl), sodium sulfate (Na2SO4), sodium carbonate (Na2CO3), sodium silicate (Na2SiO4), potassium chloride (KCl), potassium sulfate (K2SO4), potassium carbonate (K2CO3) and potassium silicate (K2SiO4).

[0013] Further, the organic carbon source in step (1) is ammonium citrate (C6H5O7(NH4)3), sodium carboxymethyl cellulose (CMC), and glucose (C6H5O7(NH4)3). 12 O6), sucrose (C 12 H 22 O 11 ), citric acid, dopamine, lactose, fructose, gelatin, maltose, malic acid, tartaric acid, oxalic acid, ammonium oxalate, ammonium acetate.

[0014] Furthermore, in step (1), methanol, ethanol, propanol, ethylene glycol and diethyl ether are used as antisolvents.

[0015] Furthermore, in step (2), the volume ratio of the antisolvent to the mixed solution A is 1:2 to 25:1.

[0016] Furthermore, in step (2), the filtered antisolvent is recovered and reused by heating or sunlight distillation.

[0017] Further, step (3) is as follows: the obtained precursor powder B is placed in a furnace, a hydrogen-argon mixture containing 0-50% hydrogen by volume is introduced, the temperature is raised to 450°C at a rate of 1-10°C / min and held for 0-3 hours, the temperature is further raised to 600-750°C and held for 2-5 hours, and then cooled to room temperature to obtain the calcined product.

[0018] Compared with the prior art, the method of the present invention has the following advantages: (1) Industrial-grade antisolvents can be recycled. Soluble inorganic salts such as NaCl (which can be recycled and reused) are used as templates. They can be cleaned by water washing and naturally dried for recycling, which significantly reduces costs; (2) The room temperature antisolvent precipitation method for synthesizing precursors does not rely on large-scale equipment, is highly efficient and consumes almost no energy; (3) A single template can replace two or more types of templates to prepare hierarchical porous structures, avoiding the mixing and consumption of multiple templates, improving the efficiency of basic research and preparation, and further reducing costs; (4) The structure of the prepared three-dimensional porous carbon material is highly controllable and the types of organic carbon sources are rich. Custom design and preparation can be carried out for different energy catalysis and storage applications; (5) The yield of the prepared product is large and the controllability is good, which makes it easy to prepare and apply on a large scale in the future. Attached Figure Description

[0019] Figure 1 The images show SEM images of the three-dimensional hierarchical porous carbon precursor (denoted as NaCl@C6H5O7(NH4)3), the pyrolysis product (denoted as NaCl@MPHC-N), and the three-dimensional hierarchical porous carbon material MPHC-N obtained after washing to remove NaCl, prepared using NaCl and C6H5O7(NH4)3 as examples in this invention.

[0020] Figure 2 This invention uses NaCl as a template, and CMC and C6H are used respectively. 12 O6 and C 12 H 22 O 11 Precursors were prepared using organic carbon sources, followed by pyrolysis and water washing to remove NaCl, resulting in three-dimensional porous carbon materials CMC-C and C6H. 12 O6-C and C 12 H 22 O 11 SEM image of -C;

[0021] Figure 3 The images show SEM images of the three-dimensional monolevel porous carbon precursor prepared by the present invention using Na2SO4 and C6H5O7(NH4)3 as an example, after pyrolysis (denoted as Na2SO4@PC-N), and the three-dimensional monolevel porous carbon material obtained by washing to remove the Na2SO4 soluble salt template.

[0022] Figure 4 The images show SEM images of the three-dimensional monolevel porous carbon precursor prepared by the present invention using Na2CO3 and C6H5O7(NH4)3 as examples, after pyrolysis (denoted as Na2CO3@PC-N), and the three-dimensional monolevel porous carbon material obtained by washing away the Na2CO3 soluble salt template with water.

[0023] Figure 5 The images show SEM images of the three-dimensional monolevel porous carbon precursor prepared by the present invention using KCl and C6H5O7(NH4)3 as an example, after pyrolysis (denoted as KCl@PC-N), and the three-dimensional monolevel porous carbon material obtained by washing to remove the KCl soluble salt template.

[0024] Figure 6 The images show SEM images of the three-dimensional monolevel porous carbon precursor prepared by the present invention using K2SO4 and C6H5O7(NH4)3 as an example, after pyrolysis (denoted as K2SO4@PC-N), and the three-dimensional monolevel porous carbon material obtained by washing to remove the K2SO4 soluble salt template.

[0025] Figure 7 Electrochemical performance of MPHC-N as a negative electrode material for sodium-ion batteries;

[0026] Figure 8 Electrochemical performance of MPHC-N as a negative electrode material for potassium-ion batteries;

[0027] Any aspects not covered in this invention are applicable to existing technologies.

[0028] The following are specific embodiments of the preparation method of the present invention. These embodiments are only used to illustrate the preparation method of the present invention in detail and do not limit the scope of protection of the claims of this application. Detailed Implementation

[0029] Example 1

[0030] At room temperature, 76.64 g of C6H5O7(NH4)3 and 240 g of NaCl were dissolved in 800 mL of deionized water and stirred for 2 h to prepare a saturated solution. Following a volume ratio of 1:9 between the aqueous solution and ethanol, 200 mL of the clarified saturated solution was rapidly poured into 1.8 L of vigorously stirred ethanol (industrial grade), and stirring continued for 10 min. During this process, taking advantage of the difference in solubility of C6H5O7(NH4)3 and NaCl in water and ethanol, the precipitated C6H5O7(NH4)3 adsorbed onto the surface of the precipitated NaCl. Finally, the NaCl adsorbed with C6H5O7(NH4)3 self-assembled to form a precursor, which, after filtration and drying at 60 °C for 6 h, yielded a three-dimensional hierarchical porous carbon-white precursor powder, NaCl@C6H5O7(NH4)3. The precursor NaCl@C6H5O7(NH4)3 was placed in a tube furnace with a 15% hydrogen-argon mixture as the carrier gas. The temperature was increased to 450℃ at a rate of 5℃ / min and held for 2 hours, then further increased to 600℃ and held for 2 hours. After cooling to room temperature, the pyrolysis product NaCl@MPHC-N was obtained. The product NaCl@MPHC-N was washed three times with deionized water to remove NaCl, and then vacuum dried at 60℃ for 6 hours to obtain the three-dimensional hierarchical porous carbon material MPHC-N.

[0031] Example 2

[0032] At room temperature, 15 g of CMC and 60 g of NaCl were dissolved in 800 mL of deionized water and stirred for 6 h to prepare a transparent viscous solution. Following a volume ratio of 1:9 between the aqueous solution and ethanol, 200 mL of this transparent viscous solution was quickly poured into 1.8 L of vigorously stirred ethanol (industrial grade), and stirring continued for 10 min. During this process, utilizing the difference in solubility of CMC and NaCl in water and ethanol, the precipitated CMC adsorbed onto the surface of the precipitated NaCl. Finally, the NaCl adsorbed with CMC self-assembled to form a precursor, which was filtered and dried at 60 °C for 6 h to obtain a three-dimensional hierarchical porous carbon-white precursor powder, NaCl@CMC. The precursor NaCl@CMC was placed in a tube furnace with a 15% hydrogen-argon mixture as the carrier gas, heated to 450 °C at a rate of 5 °C / min and held for 2 h, then further heated to 600 °C and held for 2 h, and cooled to room temperature to obtain the pyrolysis product NaCl@CMC-C. The product NaCl@CMC-C was washed three times with deionized water to remove NaCl, and then vacuum dried at 60℃ for 6 hours to obtain the three-dimensional hierarchical porous carbon material CMC-C.

[0033] Example 3

[0034] At room temperature, 230g of C6H 12 O6 and 240g of NaCl were dissolved in 800mL of deionized water and stirred for 2 hours to prepare a saturated solution. Following a volume ratio of 1:9 between the aqueous solution and ethanol, 200mL of the saturated solution was quickly poured into 1.8L of vigorously stirred ethanol (industrial grade), and stirring was continued for 10 minutes. During this process, C6H... 12 The difference in solubility of O6 and NaCl in water and ethanol leads to the precipitation of C6H. 12 O6 will adsorb onto the surface of the precipitated NaCl. Ultimately, C6H will be adsorbed. 12 NaCl self-assembles into a precursor from O6, which is then filtered and dried at 60°C for 6 hours to obtain a three-dimensional hierarchical porous carbon-white precursor powder, NaCl@C6H. 12 O6. The precursor NaCl@C6H 12 O6 was placed in a tube furnace with a 15% hydrogen-argon mixture as the carrier gas. The temperature was increased to 450℃ at a rate of 5℃ / min and held for 2 hours. The temperature was then further increased to 600℃ and held for 2 hours. After cooling to room temperature, the pyrolysis product NaCl@C6H was obtained. 12 O6-C. The product NaCl@C6H 12 O6-C was washed three times with deionized water to remove NaCl, and then vacuum dried at 60℃ for 6 h to obtain the three-dimensional hierarchical porous carbon material C6H. 12 O6-C.

[0035] Example 4

[0036] At room temperature, 430g of C 12 H 22 O 11 Dissolve 240g of NaCl in 800mL of deionized water and stir for 2 hours to prepare a saturated solution. Using an aqueous solution to ethanol volume ratio of 1:9, quickly pour 200mL of the saturated solution into 1.8L of vigorously stirred ethanol (industrial grade), and continue stirring for 10 minutes. During this process, utilize C... 12 H 22 O 11 Due to the difference in solubility of NaCl in water and ethanol, the precipitated C 12 H 22 O 11 It will adsorb onto the surface of the precipitated NaCl. Ultimately, the adsorbed C... 12 H 22 O 11 NaCl self-assembled to form a precursor, which was then filtered and dried at 60°C for 6 hours to finally obtain a three-dimensional hierarchical porous carbon-white precursor powder, NaCl@C. 12 H 22 O 11 The precursor NaCl@C 12 H 22 O 11 The mixture was placed in a tube furnace with a 15% hydrogen-argon mixture as the carrier gas. The temperature was increased to 450℃ at a rate of 5℃ / min and held for 2 hours. The temperature was then further increased to 600℃ and held for 2 hours. After cooling to room temperature, the pyrolysis product NaCl@C was obtained. 12 H 22 O 11 -C. The product NaCl@C 12 H 22 O 11 -C was washed three times with deionized water to remove NaCl, and then vacuum dried at 60℃ for 6 hours to obtain three-dimensional hierarchical porous carbon material C. 12 H 22 O 11 -C.

[0037] Example 5

[0038] At room temperature, 1.97 g of C6H5O7(NH4)3 and 15 g of Na2SO4 were dissolved in 50 mL of deionized water at a carbon atom to soluble salt ratio of 1:2, and stirred for 1 h to prepare a clear solution. Following a volume ratio of 1:16 between the aqueous solution and ethanol, 50 mL of the above clear solution was quickly poured into 800 mL of vigorously stirred ethanol (industrial grade), and stirring continued for 5 min. Finally, the Na2SO4 soluble salt template adsorbed with C6H5O7(NH4)3 self-assembled to form a precursor. After filtration and drying at 50 °C for 5 h, a three-dimensional single-level porous carbon-white precursor powder was obtained. The precursor powder was placed in a tube furnace with a 5% hydrogen-argon mixture as the carrier gas, heated to 450 °C at a rate of 5 °C / min and held for 2 h, then further heated to 600 °C and held for 2 h, and cooled to room temperature to obtain the pyrolysis product Na2SO4@PC-N. The product was washed three times with deionized water to remove the corresponding soluble salt template, and then vacuum dried at 60°C for 6 hours to obtain the three-dimensional single-level porous carbon material PC-N.

[0039] Example 6

[0040] At room temperature, 2.64 g of C6H5O7(NH4)3 and 15 g of Na2CO3 were dissolved in 50 mL of deionized water at a carbon atom to soluble salt ratio of 1:2, and stirred for 1 h to prepare a clear solution. Following a volume ratio of 1:16 between the aqueous solution and ethanol, 50 mL of the above clear solution was quickly poured into 800 mL of vigorously stirred ethanol (industrial grade), and stirring continued for 5 min. Finally, the Na2CO3 soluble salt template adsorbed with C6H5O7(NH4)3 self-assembled to form a precursor. After filtration and drying at 50 °C for 5 h, a three-dimensional single-level porous carbon-white precursor powder was obtained. The precursor powder was placed in a tube furnace with a 5% hydrogen-argon mixture as the carrier gas, heated to 450 °C at 5 °C / min and held for 2 h, then further heated to 600 °C and held for 2 h, and cooled to room temperature to obtain the pyrolysis product Na2CO3@PC-N. The product was washed three times with deionized water to remove the corresponding soluble salt template, and then vacuum dried at 60°C for 6 hours to obtain the three-dimensional single-level porous carbon material PC-N.

[0041] Example 7

[0042] At room temperature, 3.75 g of C6H5O7(NH4)3 and 15 g of KCl were dissolved in 50 mL of deionized water at a carbon atom to soluble salt ratio of 1:2, and stirred for 1 h to prepare a clear solution. Following a volume ratio of 1:16 between the aqueous solution and ethanol, 50 mL of the above clear solution was quickly poured into 800 mL of vigorously stirred ethanol (industrial grade), and stirring continued for 5 min. Finally, the KCl soluble salt template adsorbed on C6H5O7(NH4)3 self-assembled to form a precursor. After filtration and drying at 50 °C for 5 h, a three-dimensional single-level porous carbon-white precursor powder was obtained. The precursor powder was placed in a tube furnace with a 5% hydrogen-argon mixture as the carrier gas, heated to 450 °C at a rate of 5 °C / min and held for 2 h, then further heated to 600 °C and held for 2 h, and cooled to room temperature to obtain the pyrolysis product KCl@PC-N. The product was washed three times with deionized water to remove the corresponding soluble salt template, and then vacuum dried at 60°C for 6 hours to obtain the three-dimensional single-level porous carbon material PC-N.

[0043] Example 8

[0044] At room temperature, following a carbon atom to soluble salt ratio of 1:2 in C6H5O7(NH4)3, 0.64 g of C6H5O7(NH4)3 and 6 g of K2SO4 (the room temperature saturation solution of K2SO4 is relatively low) were dissolved in 50 mL of deionized water and stirred for 1 h to prepare a clear solution. Following a volume ratio of 1:16 between the aqueous solution and ethanol, 50 mL of the above clear solution was quickly poured into 800 mL of vigorously stirred ethanol (industrial grade) and stirred for another 5 min. Finally, the K2SO4 soluble salt template adsorbed on C6H5O7(NH4)3 self-assembled to form a precursor. After filtration and drying at 50 °C for 5 h, a three-dimensional, single-level porous, carbon-white precursor powder was obtained. The precursor powder was placed in a tube furnace with a 5% hydrogen-argon mixture as the carrier gas. The temperature was increased to 450℃ at 5℃ / min and held for 2 hours, then increased to 600℃ and held for 2 hours. After cooling to room temperature, the pyrolysis product K2SO4@PC-N was obtained. The product was washed three times with deionized water to remove the corresponding soluble salt template, and then vacuum dried at 60℃ for 6 hours to obtain the three-dimensional single-level porous carbon material PC-N.

Claims

1. A method for rapid and controllable preparation of three-dimensional porous carbon materials, utilizing soluble inorganic salts as templates, selecting organic carbon sources, and preparing three-dimensional porous carbon materials through room temperature antisolvent precipitation and one-step pyrolysis, comprising the following steps: (1) Select one or more soluble inorganic salts as salt templates, select one or more organic carbon sources, dissolve the organic carbon sources and salt templates in water to obtain mixed solution A; (2) Using methanol, ethanol, propanol or ethylene glycol as antisolvent, in step (2), the volume ratio of antisolvent to mixed solution A is 1:2 to 25:1; the obtained mixed solution A is poured into antisolvent, filtered and dried to obtain a white precursor powder labeled as B; (3) The precursor powder B prepared by calcination under a reducing atmosphere is used to obtain the calcined product; (4) Remove the soluble salt template to prepare a three-dimensional porous carbon material.

2. The method for rapid and controllable preparation of three-dimensional porous carbon materials according to claim 1, characterized in that, In step (1), the molar mass ratio of carbon atoms in the organic carbon source to the soluble salt template is 1:2 to 3:

1.

3. The method for rapid and controllable preparation of three-dimensional porous carbon materials according to claim 1, characterized in that, In step (1), the soluble inorganic salt templates are sodium chloride (NaCl), sodium sulfate (Na2SO4), sodium carbonate (Na2CO3), sodium silicate (Na2SiO4), potassium chloride (KCl), potassium sulfate (K2SO4), potassium carbonate (K2CO3), and potassium silicate (K2SiO4).

4. The method for rapid and controllable preparation of three-dimensional porous carbon materials according to claim 1, characterized in that, The organic carbon source in step (1) is ammonium citrate (C6H5O7(NH4)3), sodium carboxymethyl cellulose, and glucose (C6H5O7(NH4)3). 12 O6), sucrose (C 12 H 22 O 11 ), citric acid, dopamine, lactose, fructose, gelatin, maltose, malic acid, tartaric acid, oxalic acid, ammonium oxalate, ammonium acetate.

5. The method for rapid and controllable preparation of three-dimensional porous carbon materials according to claim 1, characterized in that, In step (2), the filtered antisolvent is recovered and reused by heating or sunlight distillation.

6. The method for rapid and controllable preparation of three-dimensional porous carbon materials according to claim 1, characterized in that, Step (3) is as follows: Place the obtained precursor powder B in a furnace, introduce a hydrogen-argon mixture containing less than 50% hydrogen by volume, heat to 450 ℃ at a rate of 1~10℃ / min and hold for 0~3 h, continue to heat to 600~750 ℃ ​​and hold for 2~5 h, and cool to room temperature to obtain the calcined product.

Images