Preparation and application of copper-nitrogen doped porous carbon

Abstract

This invention discloses the preparation and application of copper-nitrogen-doped porous carbon. The preparation method of the nitrogen-doped porous carbon includes the following steps: 1) dissolving a copper source in excess concentrated ammonia water, then adding porous carbon, and ultrasonically treating to obtain a suspension; 2) drying the suspension to obtain a powder, transferring it to a tube furnace, and heat-treating it in an inert atmosphere; 3) washing and drying the product to obtain copper-nitrogen-doped porous carbon. This invention utilizes the strong complexing ability of copper ions with nitrogen-containing ligands to generate stable copper-ammonia complexes, which then uniformly adhere to the surface of porous carbon through adsorption under ultrasonic conditions. Finally, copper and nitrogen are doped onto the surface of the porous carbon through heat treatment. The copper-nitrogen-doped porous carbon prepared by this invention exhibits excellent energy density and power density, making it an ideal electrode material for supercapacitors.

Description

Technical Field

[0001] This invention belongs to the field of copper-nitrogen-doped porous carbon electrodes, specifically relating to the preparation and application of copper-nitrogen-doped porous carbon. Background Technology

[0002] Supercapacitors are a new type of energy storage device that falls between traditional capacitors and batteries, offering advantages such as fast charging and discharging speeds, long cycle life, and high energy density. Electrode materials are a key factor affecting the electrochemical performance of supercapacitors. Porous carbon is widely used as an electrode material in supercapacitors due to its large specific surface area, good chemical stability, and low cost. However, porous carbon electrode materials suffer from poor conductivity, which limits the improvement of supercapacitor performance.

[0003] Copper doping in 3D transition metals is a feasible approach, as copper possesses excellent conductivity, and doping it onto the surface of porous carbon can enhance its conductivity. Current techniques typically involve loading single copper particles onto the surface of porous carbon to improve conductivity, or nitrogen doping of porous carbon to improve conductivity and energy density. However, copper loaded onto the surface of porous carbon is prone to detachment during charge-discharge processes, leading to decreased electrochemical stability. Nitrogen-doped porous carbon, due to process limitations, often has a low nitrogen content, resulting in insufficient improvement in conductivity. Therefore, there is an urgent need for a copper-nitrogen-doped porous carbon to improve the conductivity and energy density of electrodes. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing copper-nitrogen-doped porous carbon and its application.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing copper-nitrogen-doped porous carbon includes the following steps:

[0007] (1) Dissolve the copper source in excess concentrated ammonia water to generate copper ammonium complex ions, then add porous carbon, place it in an ultrasonic reactor, and ultrasonically treat it to obtain a suspension;

[0008] (2) The above suspension is dried to obtain powder, and the powder is transferred to a tube furnace and heat-treated in an inert atmosphere at a temperature of 400~600℃ for 30~120min to obtain the product.

[0009] (3) The above product was washed with water and dried to obtain copper-nitrogen doped porous carbon.

[0010] In step (1), the copper source is one or both of copper chloride and cuprous chloride.

[0011] In step (1), the mass ratio of the copper source and the porous carbon is 1:1 to 1:9, preferably 1:3 to 1:6. Using this ratio range, the copper ammonia complex ions can be more evenly dispersed on the surface of the porous carbon.

[0012] In step (1), the ultrasonic treatment time is 5 to 30 minutes.

[0013] In step (2), the inert atmosphere is either argon or nitrogen.

[0014] In step (2), the heating rate of the heat treatment is 5~10℃ / min.

[0015] In step (3), the product is washed with deionized water 1 to 3 times and then dried at 60 to 105°C.

[0016] In step (3), the specific surface area of ​​the prepared copper-nitrogen-doped porous carbon is 800~3000 m². 2 / g.

[0017] Furthermore, the heat treatment temperature in step (2) is 400~500℃. Using this temperature range, the heat treatment has a lower impact on the porous carbon structure.

[0018] The application of copper-nitrogen-doped porous carbon in supercapacitors: copper-nitrogen-doped porous carbon is used as an electrode material to assemble a supercapacitor.

[0019] This invention utilizes the strong complexing ability of copper ions with nitrogen-containing ligands to generate stable copper-ammonia complexes, which are then uniformly attached to the surface of porous carbon through adsorption under ultrasonic conditions. Finally, copper and nitrogen are doped onto the surface of porous carbon through heat treatment.

[0020] The present invention has the following beneficial effects

[0021] 1. Copper reacts with excess concentrated ammonia to form copper-ammonia complex ions. Copper has a very strong complexing ability for nitrogen-containing ligands, which can generate stable Cu-N coordination centers, such as Cu-N2 and Cu-N4. This not only improves the conductivity of porous carbon and is beneficial to electrochemical stability, but also helps nitrogen to be doped into the carbon framework, thereby enhancing the active sites of porous carbon and thus improving its conductivity and energy density.

[0022] 2. When copper-nitrogen-doped porous carbon is used as an electrode material for supercapacitors, it exhibits excellent electrochemical performance. This technology has a simple and easy production process, is readily industrialized, and can bring good economic benefits.

[0023] 3. Compared with the prior art, the copper-nitrogen-doped porous carbon prepared by this invention has excellent energy density and power density, and is an ideal electrode material for supercapacitors. It has good application prospects in power substations and electric vehicle batteries. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the synthesis of copper-nitrogen-doped porous carbon prepared in Example 1.

[0025] Figure 2 Elemental analysis and Raman spectra of the copper-nitrogen-doped porous carbon prepared in Example 1 are shown. (a) is the XPS full spectrum of the copper-nitrogen-doped porous carbon; (b) is the Cu 2p spectrum of the copper-nitrogen-doped porous carbon. 3 / 2 Figure (c) shows the N1s spectrum of copper-nitrogen-doped porous carbon; Figure (d) shows the Raman spectrum of copper-nitrogen-doped porous carbon.

[0026] Figure 3 The constant current charge-discharge curves are for the copper-nitrogen-doped porous carbon prepared in Example 1. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the scope of protection of the present invention is not limited to these embodiments.

[0028] Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Example 1

[0029] A method for preparing copper-nitrogen-doped porous carbon includes the following steps:

[0030] (1) Weigh copper chloride and porous carbon at a mass ratio of 1:4. First, dissolve copper chloride in excess concentrated ammonia water, then add porous carbon, and place it in an ultrasonic reactor for ultrasonic treatment for 10 minutes to obtain a suspension.

[0031] (2) The above suspension was dried to obtain powder, and then the powder was placed in a tube furnace for heat treatment. The heat treatment process was argon atmosphere, and the temperature was raised to 500°C at a rate of 5°C / min and heated for 30min to obtain the product.

[0032] (3) After the tubular furnace has cooled to room temperature, the product is taken out, washed three times with deionized water, and then vacuum dried at 60°C for 12 h to obtain copper-nitrogen-doped porous carbon.

[0033] The copper-nitrogen-doped porous carbon prepared in this embodiment has a specific surface area of ​​2500 m². 2 / g. Copper-nitrogen-doped porous carbon was assembled as an electrode onto a supercapacitor electrode, achieving a specific capacitance of 1350 F / g at a current density of 0.5 A / g, with a capacity retention of 90% after 10,000 cycles.

[0034] Figure 2 Elemental analysis and Raman spectra of the copper-nitrogen-doped porous carbon prepared in Example 1. Figure 2 (a) It can be seen that the appearance of Cu and N characteristic peaks indicates that Cu and N elements are present in the prepared copper-nitrogen-doped porous carbon; Figure 2 (b) is for Cu2p 3 / 2 The peak fitting results show that Cu 2p peaks are located at 932.90 eV and 934.42 eV. 3 / 2 The photoelectron peaks correspond to Cu + and Cu 2 + The binding energies at 952.61 eV and 954.17 eV are respectively for Cu + and Cu 2+ Cu 2p 1 / 2 Photoelectron peak; from Figure 2 As shown in (c), the characteristic peak at 399.10 eV corresponds to pyridine N, the characteristic peak at 400.37 eV corresponds to pyrrole N, the peak at 401.74 eV corresponds to quaternary ammonium N, and the peak at 402.80 eV corresponds to pyridine N oxide. Figure 2 (d) is the Raman spectrum of copper-nitrogen-doped porous carbon at 1358 cm⁻¹. -1 and 1582 cm -1 Nearby are two characteristic peaks corresponding to the D and G peaks of carbon materials, respectively, which can reflect the structural disorder, defect degree and graphitization degree of carbon materials.

[0035] Figure 3 The constant current charge-discharge curves of the copper-nitrogen-doped porous carbon prepared in Example 1 are shown in the figure. The initial discharge specific capacitance of the copper-nitrogen-doped porous carbon at different current densities can be obtained from the figure. The results show that the specific capacitances at current densities of 0.5, 1, 2, 4, 6, 8, and 10 A / g are 1350, 1040.5, 925.9, 888.9, 852.3, 808.1, and 766.3 F / g, respectively. Example 2

[0036] A method for preparing copper-nitrogen-doped porous carbon includes the following steps:

[0037] (1) Weigh copper chloride and porous carbon at a mass ratio of 1:2. First, dissolve copper chloride in excess concentrated ammonia water, then add porous carbon, and place it in an ultrasonic reactor for ultrasonic treatment for 10 minutes to obtain a suspension.

[0038] (2) The suspension was dried to obtain powder, and then the powder was placed in a tube furnace for heat treatment. The heat treatment process was argon atmosphere, and the temperature was raised to 400℃ at a rate of 5℃ / min and heated for 30min to obtain the product.

[0039] (3) After the tubular furnace has cooled to room temperature, the product is taken out and washed three times with deionized water, and then vacuum dried at 60°C for 12 h to obtain copper-nitrogen doped porous carbon.

[0040] The copper-nitrogen-doped porous carbon prepared in this embodiment has a specific surface area of ​​1500 m². 2 / g. When copper-nitrogen-doped porous carbon is assembled as an electrode onto a supercapacitor electrode, a specific capacitance of 950 F / g can be obtained at a current density of 0.5 A / g, and the capacity retention rate is 92% after 10,000 cycles. Example 3

[0041] A method for preparing copper-nitrogen-doped porous carbon includes the following steps:

[0042] (1) Weigh copper chloride and porous carbon in a mass ratio of 1:1. First, dissolve copper chloride in excess concentrated ammonia water, then add porous carbon, place in an ultrasonic reactor and sonicate for 10 min to obtain a suspension.

[0043] (2) The suspension was dried to obtain powder, and then the powder was placed in a tube furnace for heat treatment. The heat treatment process was argon atmosphere, and the temperature was raised to 600℃ at a rate of 5℃ / min and heated for 30min to obtain the product.

[0044] (3) After the tubular furnace has cooled to room temperature naturally, the product is taken out, washed three times with deionized water, and then vacuum dried at 60°C for 12 h to obtain copper-nitrogen doped porous carbon.

[0045] The copper-nitrogen-doped porous carbon prepared in this embodiment has a specific surface area of ​​1200 m². 2 / g, copper-nitrogen-doped porous carbon was assembled as an electrode onto a supercapacitor electrode, and a specific capacitance of 430 F / g was obtained at a current density of 0.5 A / g, with a capacity retention of 95% after 10,000 cycles.

Claims

1. A method for preparing copper-nitrogen-doped porous carbon, characterized in that, Includes the following steps: (1) Dissolve the copper source in excess concentrated ammonia water, then add porous carbon, place it in an ultrasonic reactor, and ultrasonically treat it to obtain a suspension. The copper source is one or two of copper chloride and cuprous chloride. (2) The above suspension is dried to obtain powder, and the powder is transferred to a tube furnace and heat-treated in an inert atmosphere at a temperature of 400~600℃ for 30~120min to obtain the product. (3) The above product was washed with water and dried to obtain copper-nitrogen doped porous carbon.

2. The method for preparing copper-nitrogen-doped porous carbon according to claim 1, characterized in that, The copper-nitrogen-doped porous carbon has a specific surface area of ​​800~3000 m². 2 / g.

3. The method for preparing copper-nitrogen-doped porous carbon according to claim 1, characterized in that, In step (1), the mass ratio of the copper source and the porous carbon is 1:1 to 1:

9.

4. The method for preparing copper-nitrogen-doped porous carbon according to claim 1, characterized in that, In step (1), the ultrasonic treatment time is 5 to 30 minutes.

5. The method for preparing copper-nitrogen-doped porous carbon according to claim 1, characterized in that, In step (2), the inert atmosphere is either argon or nitrogen.

6. The method for preparing copper-nitrogen-doped porous carbon according to claim 1, characterized in that, In step (2), the heating rate of the heat treatment is 5~10℃ / min.

7. The method for preparing copper-nitrogen-doped porous carbon according to claim 1, characterized in that, In step (3), the product is washed with deionized water 1 to 3 times and then dried at 60 to 105°C.

8. Copper-nitrogen-doped porous carbon obtained by the preparation method according to any one of claims 1 to 7.

9. The application of copper-nitrogen-doped porous carbon as described in claim 8 in supercapacitors.

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