A method for preparing nitrogen-doped carbon rod array using PECVD and its application

Abstract

The present invention discloses a method and application of preparing nitrogen-doped carbon rod arrays by PECVD, and relates to the technical field of carbon material preparation; the preparation method comprises the following steps: (1) ultrasonically cleaning a carbon substrate 1-3 times, drying, and obtaining a pretreated carbon substrate; (2) placing the pretreated carbon substrate obtained in step (1) in a radio frequency plasma device, evacuating, and then introducing a liquid reagent containing nitrogen and carbon, and introducing argon gas, performing plasma chemical vapor deposition, cooling to room temperature, and obtaining a nitrogen-doped carbon rod array. The present invention also applies the carbon rod array to the field of catalysis and / or batteries. The present invention effectively solves the problems of time-consuming and labor-intensive traditional preparation methods, complex operations, high processing temperatures, extreme dangers, and high energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of carbon material preparation, and in particular to a method for preparing a nitrogen-doped carbon rod array by utilizing PECVD and an application thereof. Background Art

[0002] Carbon materials have the advantages of low mass density, good flexibility, large specific surface area, excellent heat resistance and acid and alkali resistance, and have been widely used in catalysis, batteries, electronics and other fields. However, carbon materials have high chemical stability and low surface reactivity, making them difficult to modify, which hinders their further development. Strong oxidizing acid treatment will destroy the structure of carbon materials, and at the same time, the types and number of functional groups formed on their surface are difficult to control. In contrast, doping carbon materials with heterogeneous elements (such as nitrogen, oxygen, boron, fluorine, etc.) has become an effective surface modification strategy, which can change the redox properties, hydrophilicity, lithium affinity and surface polarity of the materials. The sizes of nitrogen atoms and carbon atoms are similar. When nitrogen atoms are doped with carbon, the structural stability of carbon materials can be guaranteed; at the same time, the electronegativity of nitrogen atoms is more negative, and doping can improve the conductivity of carbon materials. Therefore, the unique properties and huge application potential of nitrogen-doped carbon materials have made them a research hotspot in energy fields such as catalysis and batteries and electronics.

[0003] However, the existing methods for preparing nitrogen-doped carbon materials are divided into the following categories: (1) High-temperature calcination method: calcining the carbon material for a long time in a nitrogen-containing atmosphere (such as nitrogen, ammonia, etc.) and high temperature conditions for nitrogen doping. This method has a very high processing temperature, a long processing time, high energy consumption, and cannot perform structural design on the carbon material. (2) Liquid phase template method: mixing a nitrogen-rich precursor of a biomass raw material (honey, shrimp shells, etc.) or a nitrogen-containing organic matter (melamine, aniline, etc.) with a template, carbonizing it at high temperature, and removing the template to obtain a nitrogen-doped carbon material. However, it is impossible to judge whether the mixture of the precursor and the template is uniform. The traditional high-temperature treatment method is time-consuming and the entire preparation process is complicated and energy-intensive. (3) Hydrothermal method: It needs to be processed in a closed cavity and under high pressure conditions. This method involves a low temperature and simple preparation, but the thermal stability of the prepared carbon material is poor, it takes a long time, and the high-pressure environment is extremely dangerous. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a method and application of preparing nitrogen-doped carbon rod arrays using PECVD, which effectively solves the problems of traditional preparation methods such as time-consuming and labor-intensive, complex operation, high processing temperature, extreme danger and high energy consumption.

[0005] The technical solution of the present invention to solve the above technical problem is as follows: a method for preparing a nitrogen-doped carbon rod array by PECVD is provided, comprising the following steps:

[0006] (1) ultrasonically cleaning the carbon substrate for 1-3 times and drying it to obtain a pretreated carbon substrate;

[0007] (2) placing the pretreated carbon substrate obtained in step (1) in a radio frequency plasma device, evacuating the device, then introducing a liquid reagent containing nitrogen and carbon, and introducing argon gas to perform plasma chemical vapor deposition, and cooling the device to room temperature to obtain a nitrogen-doped carbon rod array.

[0008] Furthermore, in step (1), the carbon substrate is ultrasonically cleaned in methanol or ethanol for 1-3 times, each time for 5-25 minutes.

[0009] Furthermore, in step (1), the carbon substrate is carbon cloth, carbon paper or carbon felt.

[0010] Further, in step (1), the size of the carbon substrate is 6-6.5×2-5.5 cm 2 .

[0011] Furthermore, in step (2), plasma chemical vapor deposition is performed at 200-800 W and 200-600° C. for 5-45 min.

[0012] Furthermore, in step (2), the liquid reagent containing nitrogen and carbon is acetonitrile, propionitrile, butyronitrile, N,N-dimethylformamide, N-methylpyrrolidone, formamide, propylenediamine, triethylamine or ethanolamine.

[0013] Furthermore, in step (2), argon gas is introduced at a concentration of 10-60 sccm.

[0014] Furthermore, in step (2), the vacuum is evacuated to 6-10 Pa, and after adding the liquid reagent, the vacuum is maintained at 15-35 Pa.

[0015] The present invention also provides a nitrogen-doped carbon rod array prepared by the method for preparing a nitrogen-doped carbon rod array by using PECVD.

[0016] Application of the nitrogen-doped carbon rod array in catalysis and / or batteries.

[0017] The present invention has the following beneficial effects:

[0018] 1. The innovation of the present invention is that the liquid source containing nitrogen and carbon is volatilized in advance to become nitrogen and carbon plasma, and then a vertically grown nitrogen-doped carbon rod array is designed on a carbon substrate in one step by using PECVD. The carbon rod array with gaps increases the specific surface area of ​​the substrate, and the rich nitrogen-containing functional groups on its surface can improve the conductivity and provide more reactive sites, which is conducive to expanding the application range of the material.

[0019] 2. The process involved in the present invention is simple to operate, can be completed with only a radio frequency plasma system, takes a short time, has high production efficiency, and can be mass-produced. The temperature used is low, the energy consumption is low, and the safety factor is high; the raw materials used are abundant and inexpensive, and no other catalysts or other substances are required, so the production cost is low and the economic benefit is high. At the same time, the morphology of the prepared material is controllable and the uniformity is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the XRD pattern of the nitrogen-doped carbon rod array obtained in Example 1;

[0021] Figure 2 This is the full XPS spectrum of the nitrogen-doped carbon rod array obtained in Example 1;

[0022] Figure 3 N1S fine spectrum of the nitrogen-doped carbon rod array obtained in Example 1;

[0023] Figure 4 is a SEM image of the nitrogen-doped carbon rod array obtained in Example 1;

[0024] Figure 5 Long cycle performance diagram of bare Li, CC / Li, and NCR / Li symmetric batteries;

[0025] Figure 6 The cycling performance diagram of the full battery assembled by the ternary positive matching of bare Li, NCR / Li and NCM;

[0026] Figure 7 This is the overpotential diagram when Li is electrodeposited on the nitrogen-doped carbon rod array obtained in Example 2. DETAILED DESCRIPTION

[0027] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0028] Example 1

[0029] A method for preparing a nitrogen-doped carbon rod array by PECVD comprises the following steps:

[0030] (1) Place carbon cloth (CC) (6.5×5.5cm 2 ) ultrasonically clean the substrate in methanol twice, each time for 15 min, and dry it at 60° C. to obtain a pretreated carbon substrate;

[0031] (2) The pretreated carbon substrate obtained in step (1) was placed in a radio frequency plasma device, evacuated to 8 Pa, and then 30 mL of acetonitrile was introduced while maintaining the vacuum degree to 25 Pa, and 40 sccm of argon was introduced. Plasma chemical vapor deposition was performed at 500 W and 400 ° C for 25 min, and cooled to room temperature to obtain a nitrogen-doped carbon rod array.

[0032] The XRD pattern, XPS full spectrum, N1S fine spectrum and SEM image of the nitrogen-doped carbon rod array obtained in Example 1 are shown as follows: Figure 1-4 shown.

[0033] Depend on Figure 1 It can be seen that the two broad diffraction peaks located at 25.9° and 44.9° correspond to the (002) and (101) crystal planes of highly disordered carbon (PDF#41-1487), respectively.

[0034] Depend on Figure 2 It can be seen that the nitrogen-doped carbon rod array obtained in Example 1 contains three elements: C, N, and O.

[0035] Depend on Figure 3 It can be seen that the nitrogen-containing functional groups on the nitrogen-doped carbon rod array obtained in Example 1 are pyridinic nitrogen, pyrrolic nitrogen, graphitic nitrogen and oxidized nitrogen, which confirms the successful introduction of nitrogen.

[0036] Depend on Figure 4 It can be seen that the nitrogen-doped carbon rod array obtained in Example 1 is a vertically grown carbon rod array structure with gaps, and the height is 1.2 μm.

[0037] The nitrogen-doped carbon rod array obtained in Example 1 was used in the field of lithium metal protection. The long cycle performance of bare Li, CC / Li, and NCR / Li symmetric batteries is shown in the figure below: Figure 5 As shown in the figure, the cycle performance of the full battery assembled by the three-element positive matching of bare Li, NCR / Li and NCM is as follows Figure 6 As shown. Among them, Figure 5 Bare Li is pure lithium, CC / Li and NCR / Li are electrodes obtained by pouring molten lithium into CC and NCR matrices in a glove box.

[0038] Depend on Figure 5 It can be seen that under the protection of the nitrogen-doped carbon rod array NCR of the present invention, the cycle stability of the symmetrical battery is improved.

[0039] Depend on Figure 6 It can be seen that under the protection of the nitrogen-doped carbon rod array NCR of the present invention, the cycle stability of the full battery is improved.

[0040] Example 2

[0041] A method for preparing a nitrogen-doped carbon rod array by PECVD comprises the following steps:

[0042] (1) Place carbon paper (CP) (6 × 2 cm 2 ) ultrasonically clean the substrate in methanol or ethanol twice, each time for 20 min, and dry it at 60° C. to obtain a pretreated carbon substrate;

[0043] (2) The pretreated carbon substrate obtained in step (1) was placed in a radio frequency plasma device, evacuated to 8 Pa, and then 30 mL of formamide was introduced while maintaining the vacuum degree at 20 Pa, and 20 sccm of argon was introduced. Plasma chemical vapor deposition was performed at 300 W and 300 ° C for 20 min, and cooled to room temperature to obtain a nitrogen-doped carbon rod array.

[0044] The nitrogen-doped carbon rod array obtained in Example 2 is used in the field of lithium metal protection. The overpotential diagram of the array during Li electrodeposition is shown in FIG. Figure 7 shown.

[0045] Depend on Figure 7 It can be seen that NCR has better lithium affinity than CP.

[0046] Example 3

[0047] A method for preparing a nitrogen-doped carbon rod array by PECVD comprises the following steps:

[0048] (1) Place carbon cloth (CC) (6×5cm 2 ) ultrasonically clean the substrate in methanol or ethanol twice, each time for 10 min, and dry it at 60° C. to obtain a pretreated carbon substrate;

[0049] (2) The pretreated carbon substrate obtained in step (1) was placed in a radio frequency plasma device, evacuated to 9 Pa, and then 30 mL of acetonitrile was introduced while maintaining the vacuum degree at 30 Pa, and 50 sccm of argon was introduced. Plasma chemical vapor deposition was performed at 600 W and 400 ° C for 20 min, and cooled to room temperature to obtain a nitrogen-doped carbon rod array.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a nitrogen-doped carbon rod array using PECVD, characterized in that: Prepared by the following steps: (1) ultrasonically cleaning the carbon substrate for 1-3 times and drying it to obtain a pretreated carbon substrate; (2) placing the pretreated carbon substrate obtained in step (1) in a radio frequency plasma device, evacuating the device, then introducing a liquid reagent containing nitrogen and carbon, and introducing argon gas to perform plasma chemical vapor deposition, and cooling the device to room temperature to obtain a nitrogen-doped carbon rod array; performing plasma chemical vapor deposition for 5-45 minutes at 200-800 W and 200-600° C.; the liquid reagent containing nitrogen and carbon is acetonitrile, propionitrile, butyronitrile, N,N-dimethylformamide, N-methylpyrrolidone, formamide, propylenediamine, triethylamine or ethanolamine.

2. The method for preparing a nitrogen-doped carbon rod array using PECVD as claimed in claim 1, characterized in that: In step (1), the carbon substrate is ultrasonically cleaned in methanol or ethanol for 1-3 times, each time for 5-25 minutes.

3. The method for preparing nitrogen-doped carbon rod arrays by PECVD according to claim 1, characterized in that: In step (1), the carbon substrate is carbon cloth, carbon paper or carbon felt.

4. The method for preparing nitrogen-doped carbon rod arrays by PECVD according to claim 1, characterized in that: In step (1), the carbon substrate size is 6-6.5×2-5.5cm 2 .

5. The method for preparing nitrogen-doped carbon rod arrays by PECVD according to claim 1, characterized in that: In step (2), argon gas is introduced at a concentration of 10-60 sccm.

6. The method for preparing nitrogen-doped carbon rod arrays by PECVD according to claim 1, characterized in that: In step (2), the vacuum is evacuated to 6-10 Pa, and after adding the liquid reagent, the vacuum is maintained at 15-35 Pa.

7. The nitrogen-doped carbon rod array prepared by the method for preparing a nitrogen-doped carbon rod array by PECVD according to any one of claims 1 to 6.

8. Use of the nitrogen-doped carbon rod array according to claim 7 in catalysis and / or batteries.

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