Preparation method and application of nitrogen-phosphorus-sulfur co-doped porous carbon

Abstract

The application belongs to the technical field of carbon materials, and proposes a preparation method of nitrogen-phosphorus-sulfur co-doped porous carbon, which comprises the following steps: A, dissolving chitosan in an acetic acid solution, stirring and dissolving to obtain a chitosan gel, then adding ferric chloride and thiocyanic acid, and performing hydrothermal treatment at 150-200 DEG C to obtain an intermediate product; B, mixing the intermediate product with potassium hypophosphite, and then performing carbonization at 800-1000 DEG C in an inert gas atmosphere to obtain a carbon material. The carbon material preparation method is simple, and the prepared carbon material has excellent electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials technology, and relates to a method for preparing nitrogen, phosphorus and sulfur co-doped porous carbon and its application. Background Technology

[0002] Currently, carbon materials are widely used in adsorbents, catalysts, fuel cells, electrode materials for secondary batteries, supercapacitors, composite materials, gas sensors, solar cells, and various electronic devices due to their excellent porous properties. Carbon materials exhibit different properties depending on their functional elements, dopants, and pore volume and size. However, current carbon materials cannot be well applied in capacitors, and their complex preparation processes and relatively high costs limit their large-scale application.

[0003] The applicant has been dedicated to the preparation of different carbon materials in order to obtain simple preparation methods and high-performance products.

[0004] The inventors have conducted some research as follows: CN110577206A Preparation method of nitrogen-containing porous carbon materials based on polyaspartic acid salt and its application; CN117069094A Preparation method and application of coral-like phosphorus-rich porous carbon electrode material ; CN116715216A Preparation method of inexpensive high specific surface area hard carbon and its application in sodium-ion batteries .

[0005] Based on the above research, in order to broaden the performance and applications of different porous carbon materials, the applicant hopes to obtain a porous carbon material with superior performance and a simple preparation method. Summary of the Invention

[0006] This invention proposes a method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon, and the porous carbon can be used in supercapacitors. The carbon material preparation method is simple, and the prepared carbon material has excellent electrochemical performance.

[0007] The technical solution of this invention is implemented as follows:

[0008] Technical Topic 1

[0009] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0010] A. Dissolve chitosan in acetic acid solution, stir to dissolve and obtain chitosan gel, then add ferric chloride and trithiocyanate, and hydrotherm at 150-200℃ to obtain intermediate product;

[0011] B. The intermediate product is mixed with potassium hypophosphite and then carbonized in an inert gas atmosphere at 800-1000℃ to obtain carbon materials.

[0012] In a preferred embodiment of the present invention, the concentration of the acetic acid solution is 4-5 wt%.

[0013] In a preferred embodiment of the present invention, the ratio of chitosan to acetic acid solution is 4-6g: 30-40ml.

[0014] In a preferred embodiment of the present invention, the mass ratio of chitosan, ferric chloride, trithiocyanate and potassium hypophosphite is 4-6:0.8-1.2:0.8-1.2:1.2-2.4.

[0015] In a preferred embodiment of the present invention, the mass ratio of chitosan, ferric chloride, trithiocyanate and potassium hypophosphite is 5:1:1:1.8.

[0016] In a preferred embodiment of the present invention, the ratio of chitosan to acetic acid solution is 5g:35ml.

[0017] In a preferred embodiment of the present invention, step A is performed hydrothermally at 180°C for 6-10 hours.

[0018] In a preferred embodiment of the present invention, step B involves carbonization at 900°C in an inert gas atmosphere for 1-2 hours.

[0019] In a preferred embodiment of the present invention, the concentration of the acetic acid solution is 5 wt%.

[0020] Technical Theme Two

[0021] This invention also provides the application of carbon materials prepared by the method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon as described in Technical Topic 1, for use in supercapacitors.

[0022] The working principle and beneficial effects of this invention are as follows:

[0023] 1. This invention provides a method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon, which has the advantages of low preparation cost and simple preparation. The carbon material prepared by the method of this invention has a large specific surface area and a porous structure, with a specific surface area reaching 1318 m². 2 With a specific capacitance of 165F / g and a stability of 83%, the material has a promising future for practical applications in supercapacitors.

[0024] 2. In this invention, chitosan is used to provide carbon support and sodium storage sites, ferric chloride is used for activation, trithiocyanate is used for doping nitrogen and sulfur, and potassium hypophosphite is used for doping phosphorus. The doping of iron, phosphorus and sulfur provides capacity for sodium storage. Attached Figure Description

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0026] Figure 1 This is an adsorption-desorption curve of the carbon material prepared in Example 3 of the present invention.

[0027] Figure 2 This is a SEM image of the carbon material prepared in Example 3 of the present invention.

[0028] Figure 3 The image shows the charge-discharge curve of the supercapacitor made of carbon material prepared in Example 3 of this invention. The test conditions were: in a 6.0M potassium hydroxide solution, the test voltage range was -0.8V to 0V. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] All substances in the formulations described in this invention are commercially available. The chitosan used in the following examples and comparative examples has an average molecular weight of 10,000 (Aladdin reagent).

[0031] Example 1

[0032] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0033] A. Dissolve 4g of chitosan in 40ml of 5wt% acetic acid solution and stir to dissolve to obtain chitosan gel. Then transfer it to a 50ml hydrothermal reactor, add 0.8g of ferric chloride and 1.2g of trithiocyanate, and hydrothermally heat at 150℃ for 10h to obtain intermediate product.

[0034] B. The intermediate product was mixed with 1.2g of potassium hypophosphate and then carbonized at 1000℃ in an inert gas atmosphere for 1h to obtain carbon material.

[0035] The carbon material was measured to have a specific capacitance of 163 F / g and a stability of 80%.

[0036] Example 2

[0037] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0038] A. Dissolve 6g of chitosan in 30ml of 5wt% acetic acid solution and stir to dissolve to obtain chitosan gel. Then transfer it to a 50ml hydrothermal reactor, add 1.2g of ferric chloride and 0.8g of trithiocyanate, and hydrothermally heat at 200℃ for 6h to obtain intermediate product.

[0039] B. The intermediate product was mixed with 2.4g of potassium hypophosphate and then carbonized at 800℃ in an inert gas atmosphere for 2h to obtain carbon material.

[0040] The carbon material was measured to have a specific capacitance of 158 F / g and a stability of 75%.

[0041] Example 3

[0042] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0043] A. Dissolve 5g of chitosan in 35ml of 5wt% acetic acid solution and stir to dissolve to obtain chitosan gel. Then transfer it to a 50ml hydrothermal reactor, add 1g of ferric chloride and 1g of trithiocyanate, and hydrothermally heat at 180℃ for 8h to obtain intermediate product.

[0044] B. The intermediate product was mixed with 1.8g of potassium hypophosphate and then carbonized at 900℃ in an inert gas atmosphere for 1.5h to obtain carbon material.

[0045] like Figure 1-3 As shown, the carbon material prepared in Example 3 was characterized by adsorption-desorption curves, SEM electron microscopy, and supercapacitor charge-discharge curves. It can be seen that this invention successfully prepared a carbon material with a rich porous structure, containing iron, nitrogen, phosphorus, and sulfur elements, with an iron content of 10.5 at, a nitrogen content of 1.8 at, a phosphorus content of 2.6 at, and a sulfur content of 1.0 at. The specific surface area of ​​the carbon material was measured to reach 1318 m². 2 The material has a specific capacitance of 165 F / g and a stability of 83%.

[0046] The supercapacitor was prepared by weighing 0.1 g of the prepared carbon material, adding a 2 wt% polytetrafluoroethylene solution, stirring with a magnetic stirrer, and drying in a 105°C oven. The dried material was then coated onto a 1.0 cm diameter circular nickel foam and dried in a 105°C vacuum drying oven for 8 hours to obtain the electrode sheet. The charge-discharge curves were tested in a 6.0 M potassium hydroxide solution, using a calomel electrode as the counter electrode and a platinum electrode as the reference electrode, within a three-electrode system. The test voltage range was -0.8 V to 0 V, and the specific capacitance of the material was calculated from the charge-discharge curves.

[0047] Example 4

[0048] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0049] A. Dissolve 5g of chitosan in 35ml of 5wt% acetic acid solution and stir to dissolve to obtain chitosan gel. Then transfer it to 50ml of hydrothermal reactor, add 0.8g of ferric chloride and 1g of trithiocyanate, and hydrothermally heat at 180℃ for 8h to obtain intermediate product.

[0050] B. The intermediate product was mixed with 2g of potassium hypophosphate and then carbonized at 900℃ in an inert gas atmosphere for 1.5h to obtain carbon material.

[0051] The carbon material was measured to have a specific capacitance of 160 F / g and a stability of 78%.

[0052] Comparative Example 1

[0053] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0054] A. Dissolve 5g of chitosan in 35ml of 5wt% acetic acid solution, stir to dissolve and obtain chitosan gel, then transfer to 50ml hydrothermal reactor, add 1g of ferric chloride, and hydrothermally heat at 180℃ for 8h to obtain intermediate product.

[0055] B. The intermediate product was mixed with 1.8g of potassium hypophosphate and then carbonized at 900℃ in an inert gas atmosphere for 1.5h to obtain carbon material.

[0056] The carbon material was measured to have a specific capacitance of 131 F / g and a stability of 51%.

[0057] Comparative Example 2

[0058] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0059] A. Dissolve 5g of chitosan in 35ml of 5wt% acetic acid solution and stir to dissolve to obtain chitosan gel. Then transfer it to 50ml of hydrothermal reactor, add 1g of ferric chloride and 1g of trithiocyanate, and hydrothermally heat at 180℃ for 8h to obtain intermediate product.

[0060] B. Carbonize the intermediate product at 900℃ in an inert gas atmosphere for 1.5h to obtain carbon material.

[0061] The carbon material was measured to have a specific capacitance of 128 F / g and a stability of 56%.

[0062] Comparative Example 3

[0063] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0064] A. Dissolve 5g of chitin with a molecular weight of 7000 in 35ml of 5wt% acetic acid solution. After stirring and dissolving, chitosan gel is obtained. Then, transfer it to a 50ml hydrothermal reactor, add 1g of ferric chloride and 1g of trithiocyanate, and hydrothermally heat at 180℃ for 8h to obtain the intermediate product.

[0065] B. The intermediate product was mixed with 1.8g of potassium hypophosphate and then carbonized at 900℃ in an inert gas atmosphere for 1.5h to obtain carbon material.

[0066] The carbon material was measured to have a specific capacitance of 147 F / g and a stability of 67%.

[0067] Comparative Example 4

[0068] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0069] A. Dissolve 5g of chitosan in 35ml of 5wt% acetic acid solution, stir to dissolve and obtain chitosan gel, then transfer to 50ml hydrothermal reactor, add 1g of ferric chloride and 1g of melamine, and hydrothermally heat at 180℃ for 8h to obtain intermediate product.

[0070] B. The intermediate product was mixed with 1.8g of potassium hypophosphate and then carbonized at 900℃ in an inert gas atmosphere for 1.5h to obtain carbon material.

[0071] The carbon material was measured to have a specific capacitance of 155 F / g and a stability of 64%.

[0072] Comparative Example 5

[0073] A method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon includes the following steps:

[0074] A. Dissolve 5g of potassium polyaspartic acid with a molecular weight of 2100 in 35ml of 5wt% acetic acid solution. After stirring and dissolving, chitosan gel is obtained. Then, transfer it to a 50ml hydrothermal reactor, add 1g of ferric chloride and 1g of trithiocyanate, and hydrothermally heat at 180℃ for 8h to obtain the intermediate product.

[0075] B. The intermediate product was mixed with 1.8g of potassium hypophosphate and then carbonized at 900℃ in an inert gas atmosphere for 1.5h to obtain carbon material.

[0076] The carbon material was measured to have a specific capacitance of 152 F / g and a stability of 61%.

[0077] The methods for determining the carbon materials in the above embodiments and comparative examples are as follows:

[0078] 1. Specific capacitance measurement

[0079] 0.1 g of the prepared carbon material was weighed and added to a 2 wt% polytetrafluoroethylene solution. After stirring with a magnetic stirrer, the mixture was dried in a 105°C oven and coated onto a 1.0 cm diameter circular nickel foam. The coated material was then dried in a 105°C vacuum drying oven for 8 hours to obtain the electrode sheet. Charge-discharge curves were tested in a 6.0 M potassium hydroxide solution, using a calomel electrode as the counter electrode and a platinum electrode as the reference electrode. The test voltage range was -0.8 V to 0 V. The specific capacitance of the material was calculated from the charge-discharge curves.

[0080] 2. Stability testing

[0081] The capacitance retention rate was measured after 5000 cycles at a current density of 1 A / g.

[0082] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing nitrogen, phosphorus and sulfur co-doped porous carbon, characterized in that, Includes the following steps: A. Dissolve chitosan in acetic acid solution, stir to dissolve and obtain chitosan gel, then add ferric chloride and trithiocyanate, and hydrotherm at 150-200℃ to obtain intermediate product; B. The intermediate product is mixed with potassium hypophosphite and then carbonized in an inert gas atmosphere at 800-1000℃ to obtain carbon materials; The mass ratio of chitosan, ferric chloride, trithiocyanate, and potassium hypophosphite is 4-6:0.8-1.2:0.8-1.2:1.2-2.

4. The average molecular weight of the chitosan is 10,000.

2. The method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon according to claim 1, characterized in that, The concentration of the acetic acid solution is 4-5 wt%.

3. The method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon according to claim 1, characterized in that, The ratio of chitosan to acetic acid solution is 4-6g: 30-40ml.

4. The method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon according to claim 1, characterized in that, The mass ratio of chitosan, ferric chloride, trithiocyanate and potassium hypophosphite is 5:1:1:1.

8.

5. The method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon according to claim 1, characterized in that, The ratio of chitosan to acetic acid solution is 5g:35ml.

6. The method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon according to claim 1, characterized in that, Step A involves hydrothermal treatment at 180℃ for 6-10 hours.

7. The method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon according to claim 1, characterized in that, Step B involves carbonizing at 900°C in an inert gas atmosphere for 1-2 hours.

8. The method for preparing nitrogen, phosphorus, and sulfur co-doped porous carbon according to claim 1, characterized in that, The concentration of the acetic acid solution is 5 wt%.

9. Use of a carbon material prepared according to the method of preparing a nitrogen, phosphorus and sulphur co-doped porous carbon according to any one of claims 1 to 8, characterized in that, Used in supercapacitors.

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