A high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel and its preparation method

Abstract

The present invention discloses a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel and a preparation method thereof, belonging to the technical fields of nanomaterials and energy science and technology. By regulating the pre-carbonization temperature, time and the amount of reaction gas used, the controllable construction of pores is realized, and a series of high-porosity carbon aerogels with customizable specific surface areas are obtained. The pre-carbonization treatment enables the organic aerogel polymer to be partially converted into amorphous carbon, and the introduction of nitrogen and oxygen reaction gases causes the amorphous carbon to react with oxygen and then carbon dioxide escapes, that is, the reaction gas has a certain etching effect on the aerogel to form rich micropores and small-sized mesopores. The present invention effectively solves the problems of low porosity and difficult regulation of specific surface area of the existing phenolic resin-based carbon aerogel, and the collapse of the three-dimensional nano-network structure caused by strong chemical activation for pore formation, etc. It is simple, efficient, low-cost and convenient for popularization and utilization.

Description

Technical Field

[0001] The present invention relates to the technical fields of nanomaterials technology and energy science technology, and particularly relates to a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel and a preparation method thereof. Background Art

[0002] Aerogel is a novel functional material with a nano-porous structure, having properties such as ultra-light weight, high specific surface area, heat insulation, sound insulation, adsorption, catalysis, etc., and has great application prospects in the fields of aerospace, building energy conservation, military, thermal insulation, etc. Phenolic resin-based carbon aerogel, due to its low price and its unique three-dimensional nano-network structure, excellent properties such as high specific surface area, abundant mesopores and high electrical conductivity, plays an irreplaceable role in the fields of gas storage, adsorption and separation, catalysis, energy storage and conversion, etc. However, the specific surface area of phenolic resin-based carbon aerogel obtained by atmospheric pressure drying and high-temperature carbonization is generally not high (<1000 m 2 / g), which limits the performance and application expansion of such materials, especially in those application scenarios related to developed pores and high specific surface area.

[0003] Currently, KOH, CO2 and water vapor, etc. are often used as activators to improve the pore structure of carbon aerogel. However, when the pore structure of carbon aerogel is adjusted by CO2, etc., the increase in the specific surface area of the material is relatively small (<1700 m 2 / g, such as Chinese Patent Publication Nos. CN 1891622 A, CN 108862237 B, CN 108854874B). Although KOH activation can generate a developed pore structure, it is very easy to cause the collapse of the three-dimensional network structure. For example, Wang et al. (Journal of Power Sources, 2008, 185, 589-594) adjusted the pore structure of phenolic resin-based carbon aerogel by KOH and found that when the ratio of the activator to the material reached 5, all pores above 10 nm in the carbon aerogel disappeared and the three-dimensional nano-network skeleton was damaged. In addition, such chemical activation methods also require subsequent acid neutralization of the excessive activator and washing to neutrality, and the process is complex and cumbersome and environmentally unfriendly. Therefore, it is of great significance for the development of such materials to develop a preparation method for phenolic resin-based carbon aerogel with high porosity, customizable specific surface area, and retention of nano-network structure. Aiming at the above technical problems, the present invention provides a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel and a preparation method thereof. Summary of the Invention

[0004] The present invention provides a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel and a preparation method thereof, effectively solving the technical problems of the existing phenolic resin-based carbon aerogel such as low specific surface area, poor controllability, and collapse of the nano-network morphology caused by chemical activation such as KOH. At the same time, a phenolic resin-based three-dimensional nano-network carbon aerogel with good morphology, ultra-high specific surface area and developed microporous / mesoporous structure, and a pre-designed specific surface area is provided.

[0005] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, characterized by comprising the following steps:

[0006] S1, using resorcinol, formaldehyde, water and cetyltrimethylammonium bromide as raw materials to prepare an organic aerogel;

[0007] S2, grinding the organic aerogel obtained in S1 into powder, drying, pre-carbonizing in a nitrogen gas stream and heating to 900-950 °C, introducing a nitrogen-oxygen mixed gas to activate for 1-4 h, and cooling to room temperature in a nitrogen gas stream to obtain a phenolic resin-based three-dimensional nano-network carbon aerogel.

[0008] Preferably, in S2, the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5.

[0009] Preferably, the gas flow rate of the nitrogen-oxygen mixed gas is 30-100 mL / min.

[0010] Preferably, in S2, the temperature of the pre-carbonization is 600-900 °C, and the heat preservation is 2 h.

[0011] Preferably, in S2, the nitrogen gas flow rate is 80 mL / min.

[0012] Preferably, in S2, the heating rate is 5 °C / min.

[0013] Preferably, in S2, the specific surface area of the phenolic resin-based three-dimensional nano-network carbon aerogel is 1179-2924 m 2 / g.

[0014] Preferably, in S1, the preparation method of the organic aerogel is: dissolving resorcinol in formaldehyde, adding water and fully dissolving, then adding cetyltrimethylammonium bromide, mixing evenly, and standing in an 85 °C oil bath for 72 h to obtain.

[0015] Preferably, the mass fraction of the formaldehyde solution is 38.5%; the dosage ratio of resorcinol, formaldehyde, water, and cetyltrimethylammonium bromide is 1 g:1.26 mL:1.46 mL:0.0066-0.026 g.

[0016] A high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel prepared according to the above preparation method.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The phenolic resin-based organic aerogel of the present invention is prepared by the sol-gel method. By regulating the pre-carbonization temperature, the treatment time and dosage of the nitrogen-oxygen mixed gas, the customized construction of pores is realized; the organic aerogel is pre-carbonized in a nitrogen gas stream, and then heated to be treated with a nitrogen-oxygen mixed gas to obtain a phenolic resin-based three-dimensional nano-network carbon aerogel with different pore structures. The pre-carbonization treatment enables the macromolecules of the organic aerogel to be partially converted into amorphous carbon. The introduction of the nitrogen-oxygen reaction gas causes the amorphous carbon to react with oxygen and then CO2 escapes, which etches the aerogel to a certain extent, thereby regulating the formation of different micropores and small-sized mesopores in the aerogel. The present invention effectively solves the problems of low specific surface area, poor controllability of the existing phenolic resin-based carbon aerogel, and the collapse of the nano-network morphology caused by chemical activation.

[0019] (2) The high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel provided by the present invention has an ultra-high specific surface area. The high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 1 has a specific surface area as high as 2924 m 2 / g.

[0020] (3) The preparation method of the high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel provided by the present invention uses a nitrogen-oxygen mixed gas as the reaction gas, integrating the advantages of high-efficiency pore formation by chemical activation and maintaining the nano-structure by physical activation. It is simple, efficient, low-cost, and convenient for popularization and utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a scanning electron microscope image of the high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 1 of the present invention;

[0022] Figure 2 is a transmission electron microscope image of the high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 1 of the present invention;

[0023] Figure 3 is a nitrogen isothermal adsorption and desorption curve graph of the high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 1 of the present invention;

[0024] Figure 4 is a cyclic performance graph of the high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 4 of the present invention as a supercapacitor electrode material. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] To enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments. However, the exemplified embodiments shall not be construed as limiting the present invention. The following test methods and detection methods are all conventional methods unless otherwise specified; the reagents and raw materials are all commercially available unless otherwise specified.

[0026] Example 1

[0027] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel includes the following steps:

[0028] S1. Add 10 g of resorcinol and 12.6 mL of a formaldehyde solution with a mass fraction of 38.5% into a 50 mL round-bottom flask, then add 14.6 mL of distilled water, stir to dissolve it fully, and then add 0.066 g of cetyltrimethylammonium bromide. Place the mixed solution in a water bath at 85 °C and let it stand for reaction for 72 h to obtain an organic aerogel.

[0029] S2. Grind the organic aerogel obtained in S1 into powder, conduct drying treatment at 100 °C for 24 h, in a nitrogen gas stream with a flow rate of 80 mL / min, increase the temperature to 900 °C at a heating rate of 5 °C / min, keep the temperature for 2 h, then increase the temperature to 950 °C at a rate of 5 °C / min, and introduce a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 4 h, and then cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0030] Example 2 (The difference from Example 1 is that the activation time is changed from 4 h to 3.75 h)

[0031] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel includes the following steps:

[0032] S1. Prepare an organic aerogel according to the steps of S1 in Example 1.

[0033] S2. Grind the organic aerogel obtained in S1 into powder, conduct drying treatment at 100 °C for 24 h, in a nitrogen gas stream with a flow rate of 80 mL / min, increase the temperature to 900 °C at a heating rate of 5 °C / min, keep the temperature for 2 h, then increase the temperature to 950 °C at a rate of 5 °C / min, and introduce a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 3.75 h, and then cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0034] Example 3 (The difference from Example 1 is that the activation time is changed from 4 h to 3.5 h)

[0035] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0036] S1, obtaining an organic aerogel according to the steps of S1 in Example 1;

[0037] S2, grinding the organic aerogel obtained in S1 into powder, drying at 100 °C for 24 h, heating to 900 °C at a heating rate of 5 °C / min in a nitrogen gas stream of 80 mL / min, holding for 2 h, then heating to 950 °C at a rate of 5 °C / min, introducing a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 3.5 h, and cooling to room temperature in a nitrogen gas stream of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0038] Example 4 (the difference from Example 1 is that the activation time is changed from 4 h to 3 h)

[0039] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0040] S1, obtaining an organic aerogel according to the steps of S1 in Example 1;

[0041] S2, grinding the organic aerogel obtained in S1 into powder, drying at 100 °C for 24 h, heating to 900 °C at a heating rate of 5 °C / min in a nitrogen gas stream of 80 mL / min, holding for 2 h, then heating to 950 °C at a rate of 5 °C / min, introducing a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 3 h, and cooling to room temperature in a nitrogen gas stream of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0042] Example 5 (the difference from Example 2 is that the activation time is changed from 4 h to 1 h)

[0043] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0044] S1, obtaining an organic aerogel according to the steps of S1 in Example 1;

[0045] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, heat it to 900 °C at a heating rate of 5 °C / min in a nitrogen gas stream with a flow rate of 80 mL / min, hold for 2 h, then heat it to 950 °C at a heating rate of 5 °C / min, introduce a nitrogen-oxygen mixture (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 1 h, and cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0046] Example 6 (The difference from Example 5 is that the gas flow rate of the nitrogen-oxygen mixture changes from 30 mL / min to 40 mL / min)

[0047] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0048] S1. Obtain an organic aerogel according to the steps of S1 in Example 1;

[0049] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, heat it to 900 °C at a heating rate of 5 °C / min in a nitrogen gas stream with a flow rate of 80 mL / min, hold for 2 h, then heat it to 950 °C at a heating rate of 5 °C / min, introduce a nitrogen-oxygen mixture (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is 95:5) at a gas flow rate of 40 mL / min for activation treatment for 1 h, and cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0050] Example 7 (The difference from Example 5 is that the gas flow rate of the nitrogen-oxygen mixture changes from 30 mL / min to 60 mL / min)

[0051] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0052] S1. Obtain an organic aerogel according to the steps of S1 in Example 1;

[0053] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, heat it to 900 °C at a heating rate of 5 °C / min in a nitrogen gas stream with a flow rate of 80 mL / min, hold for 2 h, then heat it to 950 °C at a heating rate of 5 °C / min, introduce a nitrogen-oxygen mixture (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is 95:5) at a gas flow rate of 60 mL / min for activation treatment for 1 h, and cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0054] Example 8 (The difference from Example 5 is that the gas flow rate of the nitrogen-oxygen mixture changes from 30 mL / min to 90 mL / min)

[0055] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0056] S1, Prepare an organic aerogel according to the steps of S1 in Example 1;

[0057] S2, Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, in a nitrogen gas flow of 80 mL / min, heat it to 900 °C at a heating rate of 5 °C / min, keep it warm for 2 h, then heat it to 950 °C at a heating rate of 5 °C / min, and introduce a nitrogen-oxygen mixture (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is 95:5) at a gas flow rate of 90 mL / min, perform activation treatment for 1 h, and cool it to room temperature in a nitrogen gas flow of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0058] Example 9 (The difference from Example 5 is that the gas flow rate of the nitrogen-oxygen mixture changes from 30 mL / min to 100 mL / min)

[0059] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0060] S1, Prepare an organic aerogel according to the steps of S1 in Example 1;

[0061] S2, Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, in a nitrogen gas flow of 80 mL / min, heat it to 900 °C at a heating rate of 5 °C / min, keep it warm for 2 h, then heat it to 950 °C at a heating rate of 5 °C / min, and introduce a nitrogen-oxygen mixture (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is 95:5) at a gas flow rate of 100 mL / min, perform activation treatment for 1 h, and cool it to room temperature in a nitrogen gas flow of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0062] Example 10 (The difference from Example 4 is that the pre-carbonization temperature and the activation temperature are the same, 900 °C)

[0063] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0064] S1, Prepare an organic aerogel according to the steps of S1 in Example 1;

[0065] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, heat it up to 900 °C at a heating rate of 5 °C / min in a nitrogen gas stream with a flow rate of 80 mL / min, keep it at this temperature for 2 h, then introduce a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 3 h, and cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0066] Example 11 (different from Example 4 in that the pre-carbonization temperature is reduced from 900 °C to 700 °C)

[0067] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0068] S1. Prepare an organic aerogel according to the steps of S1 in Example 1;

[0069] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, heat it up to 700 °C at a heating rate of 5 °C / min in a nitrogen gas stream with a flow rate of 80 mL / min, keep it at this temperature for 2 h, then heat it up to 950 °C at a heating rate of 5 °C / min, introduce a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 3 h, and cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0070] Example 12 (different from Example 4 in that the pre-carbonization temperature is changed from 900 °C to 600 °C)

[0071] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0072] S1. Prepare an organic aerogel according to the steps of S1 in Example 1;

[0073] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, heat it up to 600 °C at a heating rate of 5 °C / min in a nitrogen gas stream with a flow rate of 80 mL / min, keep it at this temperature for 2 h, then heat it up to 950 °C at a heating rate of 5 °C / min, introduce a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 3 h, and cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0074] Example 13 (parameters of the precursor material are changed)

[0075] A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0076] S1. Add 10 g of resorcinol and 12.6 mL of a formaldehyde solution with a mass fraction of 38.5% to a 50 mL round-bottom flask, then add 14.6 mL of distilled water, stir to dissolve it fully, and then add 0.26 g of cetyltrimethylammonium bromide. Place the mixed solution in a water bath at 85 °C and let it stand and react for 72 h to obtain an organic aerogel.

[0077] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, in a nitrogen gas stream with a flow rate of 80 mL / min, heat it at a heating rate of 5 °C / min to 900 °C, keep it at this temperature for 2 h, then heat it at a heating rate of 5 °C / min to 950 °C, and introduce a nitrogen-oxygen mixed gas (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5) at a gas flow rate of 80 mL / min for activation treatment for 1 h, and then cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel.

[0078] To further illustrate the effects of the present invention, the present invention also sets a comparative example as follows:

[0079] Comparative Example 1 (Difference from Example 4: Preparation of carbon aerogel without the action of nitrogen-oxygen mixed gas) A preparation method of a phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0080] S1. Prepare an organic aerogel according to the steps of S1 in Example 1.

[0081] S2. Grind the organic aerogel obtained in S1 into powder, dry it at 100 °C for 24 h, in a nitrogen gas stream with a flow rate of 80 mL / min, heat it at a heating rate of 5 °C / min to 900 °C, keep it at this temperature for 2 h, then heat it at a heating rate of 5 °C / min to 950 °C, introduce nitrogen at a gas flow rate of 30 mL / min, keep it at this temperature for 3 h, and then cool it to room temperature in a nitrogen gas stream with a flow rate of 80 mL / min to obtain a phenolic resin-based three-dimensional nano-network carbon aerogel.

[0082] Comparative Example 2 (Preparation of carbon aerogel under the action of potassium hydroxide)

[0083] A preparation method of a phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0084] S1. Prepare an organic aerogel according to the steps of S1 in Example 1.

[0085] S2. Grind the organic aerogel obtained in S1 into powder, conduct drying treatment at 100 °C for 24 h, in a nitrogen gas stream at 80 mL / min, raise the temperature to 500 °C at a heating rate of 5 °C / min, keep the temperature for 3 h, and then cool it to room temperature in a nitrogen gas stream at 80 mL / min to obtain a pre-carbonized sample. Then, weigh a certain amount of KOH (2 g) and the pre-carbonized sample (500 mg) respectively. Add a small amount of deionized water to the nickel pot to completely dissolve KOH, and then add the sample to be activated in powder form to the nickel pot. Place it on a magnetic stirrer and mix well and shake evenly. Then, dry it at 100 °C for 24 h. Put the nickel pot into a carbonization furnace, under nitrogen protection at 80 mL / min, raise the temperature to 900 °C at a heating rate of 5 °C / min, keep the temperature for 3 h, and then cool it to room temperature in a nitrogen gas stream at 80 mL / min to obtain a carbon aerogel with collapsed morphology.

[0086] Comparative Example 3 (changing the activation time: activating for 0.5 h)

[0087] A preparation method of a phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0088] S1. The organic aerogel prepared in Example 1;

[0089] S2. Grind the organic aerogel obtained in S1 into powder, conduct drying treatment at 100 °C for 24 h, in a nitrogen gas stream at 80 mL / min, raise the temperature to 900 °C at a heating rate of 5 °C / min, keep the temperature for 2 h, then raise the temperature to 950 °C at a heating rate of 5 °C / min, and introduce a nitrogen-oxygen mixture (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 0.5 h, and then cool it to room temperature in a nitrogen gas stream at 80 mL / min to obtain a phenolic resin-based three-dimensional nano-network carbon aerogel.

[0090] Comparative Example 4 (changing the activation time: activating for 4.5 h)

[0091] A preparation method of a phenolic resin-based three-dimensional nano-network carbon aerogel, comprising the following steps:

[0092] S1. The organic aerogel prepared in Example 1;

[0093] S2. Grind the organic aerogel of S1 into powder, dry it at 100 °C for 24 h, heat it up to 900 °C at a heating rate of 5 °C / min in a nitrogen gas stream of 80 mL / min, keep it at this temperature for 2 h, then heat it up to 950 °C at a heating rate of 5 °C / min, and introduce a nitrogen-oxygen mixture (the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixture is 95:5) at a gas flow rate of 30 mL / min for activation treatment for 4.5 h. Then cool it to room temperature in a nitrogen gas stream of 80 mL / min to obtain a phenolic resin-based three-dimensional nano-network carbon aerogel. However, due to the too long activation treatment time, the yield of the material is too low, the preparation controllability is too poor, and the precursor material is easily completely etched, making it impossible to provide the accurate specific surface area of this type of material.

[0094] For the phenolic resin-based three-dimensional nano-network carbon aerogels prepared in Examples 1-13 and Comparative Examples 1-3 of the present invention, the BET method was used to calculate the specific surface area, and the t-plot method was used to calculate the micropore surface area and micropore volume V mic for detection, and the results are shown in Table 1.

[0095] Table 1 Data table of specific surface area, micropore surface area and micropore volume of the carbon aerogel of the present invention

[0096] <![CDATA[BET specific surface area / m 2 g -1 > <![CDATA[Micropore surface area / m 2 g -1 > <![CDATA[Micropore volume V mic / cm 3 g -1 > Example 1 2924 517 0.25 Example 2 2733 753 0.31 Example 3 2439 1351 0.61 Example 4 1972 1189 0.55 Example 5 1179 949 0.44 Example 6 1255 1012 0.50 Example 7 1579 1098 0.53 Example 8 2089 1254 0.58 Example 9 2318 1623 0.80 Example 10 1843 1206 0.56 Example 11 1978 1176 0.51 Example 12 1987 1160 0.49 Example 13 1301 986 0.47 Comparative Example 1 782 605 0.28 Comparative Example 2 834 564 0.26 Comparative Example 3 901 712 0.31

[0097] As can be seen from Table 1, in the preparation method of the phenolic resin-based three-dimensional nano-network carbon aerogel provided by the present invention, the pre-carbonization treatment enables the organic aerogel polymer to be converted into amorphous carbon to a certain extent. Subsequently, introducing a nitrogen-oxygen mixture causes the amorphous carbon to react with oxygen and then carbon dioxide escapes, resulting in a certain etching effect on the aerogel. The specific surface area of the obtained phenolic resin-based three-dimensional nano-network carbon aerogel is as high as 2924 m 2 / g. Through analysis, it can be seen that this strategy has controllability and predictability for the construction of material pores. For example, in Examples 1-5, Comparative Examples 1 and 3, it was found that under the same gas flow rate and heat treatment temperature, the specific surface area and the reaction gas treatment time satisfy Equation (1). At this time, the gas flow rate of the reaction gas is 30 mL / min, and the oxygen concentration in the reaction gas is 5%. Therefore, during the reaction gas treatment process, the oxygen consumption per hour is about 4.02 mmol. The consumed oxygen reacts with the same amount of activated precursor to generate CO2. Since carbon is in excess during the preparation process, the utilization rate of the introduced oxygen reaches 100%. Based on this, the carbon etching amount per hour should be consistent, which is consistent with the results observed during the preparation process (the loss amount per hour is about 50-60 mg). Further, by adjusting the reaction gas flow rate, it was found that on the premise of a constant oxygen reaction amount, an approximate pore structure can be obtained by arbitrarily changing the process parameters (such as Example 4 and Example 8), and the specific surface area and the reaction gas flow rate satisfy Equation (2).

[0098] S BET = 127.6x 2 + 833 (1)

[0099] S BET = 0.14y 2 + 899 (2)

[0100] where S BET is the specific surface area of the material, x is the reaction gas treatment time (h), and y is the reaction gas flow rate (mL / min).

[0101] For the phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 1 of the present invention, morphological analysis was carried out. The prepared sample was fixed on the sample stage with conductive glue, and the structural morphology of the sample was observed with a Nova field emission scanning electron microscope produced by FEI of the United States. The scanning electron microscope image of the phenolic resin-based three-dimensional nano-network carbon aerogel is as Figure 1 shown. A small amount of the prepared phenolic resin-based three-dimensional nano-network carbon aerogel powder was taken, ultrasonically dispersed in absolute ethanol, and part of the sample was fished with a copper mesh. After the absolute ethanol volatilized, the sample structure was observed with a transmission electron microscope. The transmission electron microscope image of the phenolic resin-based three-dimensional nano-network carbon aerogel is as Figure 2 shown.

[0102] It can be seen from Figure 1 that the highly porous phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 1 of the present invention is formed by the aggregation and connection of nano-spheres about dozens of nanometers in size, constituting a three-dimensional network porous framework; Figure 2 It can be clearly observed that the phenolic resin-based three-dimensional nano-network carbon aerogel is composed of nano-particles, which crosslink with each other to form a three-dimensional network structure. It can be seen from Figure 3 that the samples all show a type IV adsorption curve. The curve shows a sharp upward trend in the low-pressure region of P / P0 = 0 - 0.1, indicating that there are a large number of micropores in the material. An upward and a hysteresis loop appear in the medium and high-pressure regions respectively, indicating the presence of mesopores and macropore structures in the material.

[0103] It can be seen from Figure 4 that using the highly porous phenolic resin-based three-dimensional nano-network carbon aerogel prepared in Example 4 of the present invention as the supercapacitor electrode material, the capacitor shows excellent specific capacitance (114.6 F g -1 ) after 10,000 cycles at a current density of 20 A / g, and the capacitance retention rate reaches 98%.

[0104] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A preparation method of a high-porosity phenolic resin-based three-dimensional nano-network carbon aerogel, characterized in that, It includes the following steps: S1. Using resorcinol, formaldehyde, water and cetyltrimethylammonium bromide as raw materials, an organic aerogel is prepared; S2. Grind the organic aerogel of S1 into powder, dry it, continue to heat it to 900 - 950 °C after pre-carbonization treatment in a nitrogen gas stream, introduce a nitrogen-oxygen mixed gas to activate for 1 - 4 h, and cool it to room temperature in a nitrogen gas stream to obtain a phenolic resin-based three-dimensional nano-network carbon aerogel with a specific surface area of 1179 - 2924 m 2 / g; the volume ratio of nitrogen to oxygen in the nitrogen-oxygen mixed gas is 95:5; the gas flow rate of the nitrogen-oxygen mixed gas is 30 - 100 mL / min; During the activation process of introducing a nitrogen-oxygen mixed gas, when the gas flow rate and the heat treatment temperature are constant, regulating the reaction gas treatment time, or when the oxygen reaction amount is constant, regulating the reaction gas flow rate can both achieve quantitative regulation of the specific surface area of the phenolic resin-based three-dimensional nano-network carbon aerogel; Among them, when the gas flow rate and the heat treatment temperature are constant, the specific surface area of the phenolic resin-based three-dimensional nano-network carbon aerogel and the reaction gas treatment time satisfy Equation (1); ； When the oxygen reaction amount is constant, the specific surface area of the phenolic resin-based three-dimensional nano-network carbon aerogel and the reaction gas flow rate satisfy Equation (2); ； Among them, S BET is the specific surface area of the phenolic resin-based three-dimensional nano-network carbon aerogel, x is the reaction gas treatment time, y is the reaction gas flow rate, and the above reaction gas is the nitrogen-oxygen mixed gas introduced.

2. The preparation method according to claim 1, characterized in that, In S2, the temperature of the pre-carbonization treatment is 600-900 °C, and the heat preservation time is 2 h.

3. The preparation method according to claim 1, wherein In S2, the nitrogen gas flow rate is 80 mL / min.

4. The preparation method according to claim 1, characterized in that, In S2, the heating rate is 5 °C / min.

5. The preparation method according to claim 1, characterized in that, In S1, the preparation method of the organic aerogel is: dissolving resorcinol in formaldehyde, adding water and fully dissolving, then adding cetyltrimethylammonium bromide, mixing evenly, and standing in an 85 °C oil bath for 72 h to obtain.

6. The preparation method according to claim 5, characterized in that, The mass fraction of the formaldehyde solution is 38.5%; the dosage ratio of resorcinol, formaldehyde, water and cetyltrimethylammonium bromide is 1 g:1.26 mL:1.46 mL:0.0066-0.026 g.

7. A highly porous phenolic resin-based three-dimensional nano-network carbon aerogel prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The specific surface area of the phenolic resin-based three-dimensional nano-network carbon aerogel is 1179~2924 m 2 / g.

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