Preparation method and application of carbon electrode material

Abstract

The invention discloses a preparation method and application of a carbon electrode material, and the preparation method comprises the following steps: preparing polyfurfural resin, preparing polyfurfural resin gel, pouring the polyfurfural resin gel into a mold, slowly heating to 160 DEG C, baking to remove excess water, demolding to obtain a precursor, and drying to obtain the carbon electrode material. The precursor is subjected to the steps of carbonization, activation, plasma enhanced reduction, plasma nitrogen doping and the like to prepare a carbon electrode; the prepared carbon electrode has the common characteristics of a carbon material, has high heat resistance, high temperature resistance, low density, superconductivity, high corrosion resistance and high thermal conductivity, and can be subjected to mirror polishing; the prepared carbon electrode material has high strength and hardness, and can be used for manufacturing electrolytic electrode materials, in the plasma doping process of a carbon electrode, nitrogen atoms replace carbon atoms in an original carbonized precursor to form different N forms, and the electro-catalytic performance of the carbon electrode material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic non-metallic materials, and specifically to a carbon electrode material, a preparation method thereof, and an application thereof. Background Art

[0002] Carbon electrode materials are a type of electrode materials used in electrochemical energy storage and electrochemical synthesis applications, and have high electrical conductivity and chemical stability. Common carbon electrode materials include: graphite, porous carbon materials, graphene, carbon nanotubes, carbon nanosheets, vitreous carbon, etc. Among them, vitreous carbon is a carbon structure material similar to glass and is also a non-crystalline new carbon structure material. It is called vitreous carbon because of its port morphology and structural characteristics similar to glass. The characteristics of vitreous carbon are high hardness and air permeability. It is widely used in many fields such as the chemical industry, metallurgical industry, electronic industry, and biological engineering. It can withstand 1.3 million times the atmospheric pressure and can withstand 600,000 times the atmospheric pressure in other directions. It is used to manufacture ultra-high temperature micro-vitreous carbon electrodes and serve as stoichiometric electrodes. Its diameter can be less than 1 mm, in the shape of a disc, cylinder, or cone, and is used as a stoichiometric electrode for the analysis of clinical biological samples, environmental samples, and thick liquids with trace amounts of stoichiometric components and coexistence of multiple compounds. It can be used for the production of medical equipment, such as dental materials and components of cardiac pacemakers. It can be used as thermal insulation materials at 3800 °C and high heat-resistant protective clothing. Special ultra-high temperature crucibles, ultra-high temperature beakers, ultra-high temperature pipe fittings, ultra-high temperature casting molds, carbon crystal wall heaters, carbon crystal heating plates, ultra-high temperature electric heaters, and vitreous carbon fiber composite panels are used for computer and mobile phone touch screens, for manufacturing high-speed typewriter typewheels and making records. The structure of vitreous carbon is different from that of graphite. It is amorphous carbon as a whole. Although it contains a microcrystalline layer structure, it is not arranged in rows but forms a polymerized jointless and poreless hexagonal structure. It is macroscopically poreless, but pores exist between the hexagonal joint layers, and the apparent density is small, about 1.3 g / cm 3 , and its basic structure is a turbostratic structure with extremely small microcrystalline size, and the microstructure is non-oriented. Summary of the Invention

[0003] The purpose of the present invention is to provide a carbon electrode material, a preparation method thereof, and an application thereof to solve the problems raised in the above background art.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a preparation method of a carbon electrode material, including the following steps:

[0006] Synthesis of polyfurfural resin gel

[0007] S1. Preparation of polyfurfural resin: Add phenol, furfural, solvent and compounded alkaline catalyst into a reaction device, heat and stir to 60 - 70 °C, and obtain brownish-red polyfurfural resin after reacting for 5 - 20 h;

[0008] S2. Preparation of polyfurfural resin gel: Add polyfurfural resin, adhesive, thickener, initiator and metal active substance into a reaction device, stir and mix evenly at room temperature to obtain brownish-red polyfurfural resin gel;

[0009] S3. Water removal: Drop tetraethyl orthosilicate into the polyfurfural resin gel, place it on a rotary evaporator to remove water, and perform vacuum dehydration after heating up to finally obtain a modified polyfurfural resin gel with the required viscosity;

[0010] S4. Curing: Add curing agent hexamethylenetetramine into the modified polyfurfural resin gel, stir and mix evenly at room temperature for crosslinking and curing, then pour it into a mold, slowly heat up, bake to remove excess water, and demold to obtain a precursor;

[0011] Preparation of carbon electrode

[0012] S5. Place the quartz boat mold containing the precursor in a muffle furnace. After placement, perform inert gas replacement three times in the muffle furnace to remove oxygen in the system, and ensure that the sample is always protected by inert gas during carbonization and cooling. The precursor is carbonized at 500 °C in an inert atmosphere to obtain a carbonized precursor;

[0013] S6. Immerse the carbonized precursor in KOH solution for 10 hours for KOH activation treatment, wash it with deionized water until neutral, and then place it in a vacuum and slowly heat for drying to obtain an activated carbonized precursor;

[0014] S7. Place the quartz boat mold carrying the activated carbonized precursor in a hot filament chemical vapor deposition device. After placement, perform hydrogen plasma gas replacement three times to remove oxygen in the system, and then perform high-temperature deposition to obtain a carbon electrode material, ensuring that the sample is always protected by hydrogen plasma gas during deposition and cooling.

[0015] Furthermore, in step S1, the molar ratio of phenol, furfural and compounded alkaline catalyst is 1:1.2 - 1.5:0.02 - 0.05; the mass ratio of phenol to solvent is 1:1 - 2; the solvent is one or more of water, methanol and ethanol.

[0016] Furthermore, in step S1, the compounded alkaline catalyst is compounded by potassium hydroxide, sodium hydroxide, sodium carbonate, cetyltrimethylammonium hydroxide, tetramethylammonium hydroxide and water with a mass ratio of 1:0.5 - 1:0.1 - 0.5:1 - 1.5:0.1 - 0.5:2 - 3.

[0017] Further, in step S2, the mass ratio of polyfurfural resin, adhesive, thickener, initiator, and metal active substance is 1: 0.08 - 0.15: 0.01 - 0.05: 0.03 - 0.1: 0.01 - 0.02.

[0018] Further, the adhesive is an organosilicon resin adhesive, the thickener is an aqueous solution of polyacrylamide or an aqueous solution of sodium polyacrylate; the initiator is one or more of potassium persulfate, ammonium persulfate, and sodium persulfate; the metal active substance is platinum diaminodinitrite or palladium diaminodinitrite.

[0019] Preferably, the thickener is an aqueous solution of polyacrylamide; the initiator is potassium persulfate; the metal active substance is platinum diaminodinitrite.

[0020] Further, in step S3, the mass ratio of polyfurfural resin gel to tetraethyl orthosilicate is 1: 0.01 - 0.04, the temperature for vacuum dehydration is 60 - 85 °C, and the time for vacuum dehydration is 1 - 5 hours.

[0021] Further, in step S4, the mass ratio of the modified polyfurfural resin gel to the curing agent hexamethylenetetramine is 1: 0.02 - 0.05; the specific baking conditions are: rising from room temperature to 50 °C at a rate of 5 - 10 °C / hour, rising from 50 °C to 80 °C at a rate of 4 - 8 °C / hour, rising from 80 °C to 100 °C at a rate of 3 - 5 °C / hour, rising from 100 °C to 160 °C at a rate of 1 - 3 °C / hour, and maintaining at 160 °C for 1 - 10 hours.

[0022] Further, in step S4, the mold size is 100 - 500 mm * 100 - 500 mm * 1 - 5 mm.

[0023] Further, in step S5, maintain the inert gas inlet velocity at 2000 sccm (standard cubic centimeters per minute, a unit of gas flow rate); the specific carbonization conditions are: rising from room temperature to 500 °C at a heating rate of 6 °C per hour, carbonizing at 500 °C for 5 - 10 hours under high temperature conditions, and then naturally cooling to room temperature to obtain a carbonized precursor.

[0024] Further, in step S6, the concentration of the KOH solution is 2 - 5 mol / L, the specific drying conditions are: rising from room temperature to 85 - 90 °C at a heating rate of 8 - 10 °C per hour, drying for 10 - 24 hours, and then naturally cooling to room temperature to obtain an activated carbonized precursor.

[0025] Further, in step S7, the specific conditions for high-temperature deposition are as follows: maintaining the hydrogen plasma at 4 Torr, with an inlet gas velocity of 100 sccm, at a heating rate of 2-5 °C per hour, heating from room temperature to 400 °C, then performing high-temperature deposition for 3-10 hours under the high-temperature condition of 400 °C. Subsequently, introducing nitrogen plasma onto the surface of the carbonization precursor; heating from 400 °C to 800 °C at a heating rate of 8-10 °C per hour, and then performing high-temperature deposition for 6-12 hours under the high-temperature condition of 800 °C. Finally, annealing the sample at 800 °C and cooling it to room temperature at a cooling rate of 10-12 °C per hour to obtain the carbon electrode material.

[0026] The present invention also provides a carbon electrode material prepared by the preparation method as described above.

[0027] The present invention also provides an application of the carbon electrode material as described above in electrochemical synthesis.

[0028] Pour the liquid resin into a mold to change the resin raw material from a liquid phase to a solid phase, obtaining a precursor of the carbon electrode. During the heating process, the intensity of the reaction of the resin at different temperatures varies greatly, so a reasonable heating curve must be determined. The curing process has a great impact on the final quality of the carbon electrode material. Unreasonable heating easily causes pores and defects inside the product, and even leads to cracking of the product.

[0029] The precursor prepared by the present invention is flatter, more transparent and crystal-clear in appearance, has a better temperature reduction effect, and the precursor will not bend or deform.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The carbon electrode prepared by the present invention has the common characteristics of carbon materials, such as high heat resistance, high temperature resistance, low density, superconductivity, high corrosion resistance and high thermal conductivity, and can be mirror-polished;

[0032] The carbon electrode prepared by the present invention has relatively high strength and hardness and can be used to manufacture electrolysis electrode materials.

[0033] During the plasma doping process of the carbon electrode prepared by the present invention, nitrogen atoms replace carbon atoms in the original carbonization precursor to form different N forms, increasing its electrocatalytic performance. Description of the Drawings

[0034] Figure 1 It is the SEM image of the carbon electrode prepared in Example 1;

[0035] Figure 2 It is the SEM image of the carbon electrode prepared in Example 4;

[0036] Figure 3 It is the product appearance image of the precursor prepared in Example 1;

[0037] Figure 4 It is the product appearance diagram of the precursor prepared in Comparative Example 1. Specific embodiments

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] Example 1

[0040] A carbon electrode and a preparation method

[0041] (1) Preparation of polyfurfural resin: Add 100 g of phenol, 127.62 g of furfural, and 150 g of water into a 500 ml reaction flask. Under nitrogen protection, start stirring and preheat to 50 °C, then add 1.06 g of a compounded basic catalyst (weight ratio: 0.2 g of potassium hydroxide, 0.12 g of sodium hydroxide, 0.04 g of sodium carbonate, 0.22 g of cetyltrimethylammonium hydroxide, 0.04 g of tetramethylammonium hydroxide, and 0.44 g of water). Raise the reaction temperature to 60 °C, stir and react for 15 hours, and then perform vacuum dehydration to obtain 220.21 g of brownish-red polyfurfural resin;

[0042] (2) Preparation of polyfurfural resin gel: Take a 500 ml four-necked flask, add 220.21 g of polyfurfural resin, 24.22 g of silicone resin adhesive, 4.4 g of thickener polyacrylamide aqueous solution, 11.01 g of initiator potassium persulfate, and 3.3 g of metal active substance dinitrodiammine platinum into the four-necked flask, and stir and mix evenly at room temperature to obtain 263.15 g of brownish-red polyfurfural resin gel.

[0043] (3) Water removal: Drop 0.5 g of tetraethyl orthosilicate into 263.15 g of the brownish-red polyfurfural resin gel obtained in step (2), and further perform vacuum dehydration. The vacuum dehydration temperature is 75 °C, and the vacuum dehydration time is 5 hours, finally obtaining 243.41 g of modified polyfurfural resin gel.

[0044] (4) Curing: Add 6.09 g of hexamine as the curing agent to the 243.41 g of modified polyfurfural resin gel obtained in step (3), stir well at room temperature until evenly mixed for crosslinking and curing, then pour it into a mold with dimensions of 500*500*5 mm. Heat it from room temperature to 50 °C at a rate of 8 °C per hour, from 50 °C to 80 °C at a rate of 6 °C per hour, from 80 °C to 100 °C at a rate of 4 °C per hour, and from 100 °C to 160 °C at a rate of 2 °C per hour. Keep it at 160 °C for 5 hours, bake to remove excess moisture, and finally demold to obtain 231.52 g of the precursor, as Figure 3 shown.

[0045] (5) Preparation of carbonized precursor: Place the quartz boat mold carrying the 231.52 g of precursor obtained in step (4) into a muffle furnace. After placement, perform three inert gas replacements in the muffle furnace to remove oxygen in the system and ensure that the sample is always protected by inert gas during carbonization and cooling. Keep the inert gas inlet rate at 2000 sccm (standard cubic centimeters per minute, a unit of gas flow rate). The precursor is heated from room temperature to 500 °C at a heating rate of 6 °C per hour in an inert atmosphere, carbonized at 500 °C for 5 hours, and then naturally cooled to room temperature to obtain 183.37 g of carbonized precursor.

[0046] (6) Preparation of activated carbonized precursor: Immerse the 183.37 g of carbonized precursor obtained in step (5) in a 2.0 mol / L KOH solution for 10 hours, wash it with a large amount of deionized water until neutral, perform KOH activation treatment, then place it in a vacuum and heat it from room temperature to 90 °C at a heating rate of 10 °C per hour, dry for 14 hours, and then naturally cool to room temperature to obtain 182.26 g of activated carbonized precursor.

[0047] (7) Preparation of carbon electrode: Place the quartz boat mold carrying the 182.26 g of activated carbonized precursor obtained in step (6) into a hot filament chemical vapor deposition equipment. After placement, perform three hydrogen plasma gas replacements in the hot filament chemical vapor deposition equipment to remove oxygen in the system and ensure that the sample is always protected by hydrogen plasma gas during deposition and cooling. Keep the hydrogen plasma gas at 4 Torr, with an inlet rate of 100 sccm, heat it from room temperature to 400 °C at a heating rate of 5 °C per hour, and perform high-temperature deposition at 400 °C for 3 hours. Subsequently, after the reduction step, introduce nitrogen plasma (500 W power, 14 Torr of N2 gas, 200 sccm inflow rate) to the surface of the carbonized precursor. Heat it from 400 °C to 800 °C at a heating rate of 8 °C per hour and perform high-temperature deposition at 800 °C for 6 hours. Finally, anneal the sample at 800 °C and cool it to room temperature at a cooling rate of 12 °C per hour. The final product is 162.88 g of carbon electrode, denoted as specimen 1.

[0048] Example 2

[0049] A carbon electrode and its preparation method

[0050] (1) Preparation of polyfurfural resin: Add 100 g of phenol, 132.73 g of furfural, and 160 g of water into a 500 ml reaction flask. Under nitrogen protection, start stirring and preheat to 50 °C, then add 1.28 g of a compound alkaline catalyst (weight ratio: 0.22 g of potassium hydroxide, 0.12 g of sodium hydroxide, 0.08 g of sodium carbonate, 0.28 g of cetyltrimethylammonium hydroxide, 0.07 g of tetramethylammonium hydroxide, and 0.51 g of water). Raise the reaction temperature to 60 °C, stir and react for 12 hours, then perform vacuum dehydration to obtain 234.01 g of brownish-red polyfurfural resin;

[0051] (2) Preparation of polyfurfural resin gel: Take a 500 ml four-necked flask, add 234.01 g of polyfurfural resin, 28.08 g of organosilicon resin adhesive, 7.02 g of thickener polyacrylamide aqueous solution, 14.04 g of initiator potassium persulfate, and 2.81 g of metal active substance dinitrodiammine platinum into the four-necked flask, and stir and mix evenly at room temperature to obtain 285.96 g of brownish-red polyfurfural resin gel.

[0052] (3) Water removal: Drop 0.37 g of tetraethyl orthosilicate into the 285.96 g of brownish-red polyfurfural resin gel obtained in step (2), and further perform vacuum dehydration. The vacuum dehydration temperature is 75 °C, and the vacuum dehydration time is 6 hours. Finally, 265.94 g of modified polyfurfural resin gel is obtained.

[0053] (4) Curing: Add 7.98 g of curing agent hexamethylenetetramine to the 265.94 g of modified polyfurfural resin gel obtained in step (3), stir and mix evenly at room temperature for crosslinking and curing, then pour it into a mold with dimensions of 500*500*5 mm. Raise the temperature from room temperature to 50 °C at a rate of 8 °C per hour, from 50 °C to 80 °C at a rate of 6 °C per hour, from 80 °C to 100 °C at a rate of 4 °C per hour, from 100 °C to 160 °C at a rate of 2 °C per hour, and maintain at 160 °C for 5 hours, bake to remove excess moisture, and finally demold to obtain 260.23 g of the precursor.

[0054] (5) Preparation of carbonization precursor: Place the quartz boat mold carrying the 260.23 g precursor obtained in step (4) into a muffle furnace. After placement, perform three inert gas replacements in the muffle furnace to remove oxygen in the system and ensure that the sample is always protected by inert gas during carbonization and cooling. Maintain the inert gas inlet rate at 2000 sccm (standard cubic centimeters per minute gas flow unit). The precursor is heated from room temperature to 500 °C at a heating rate of 7 °C per hour in an inert atmosphere, carbonized at 500 °C for 8 hours under high temperature conditions, and then naturally cooled to room temperature to obtain 208.18 g of carbonization precursor.

[0055] (6) Preparation of activated carbonization precursor: Immerse the 208.18 g carbonization precursor obtained in step (5) in a 3.0 mol / L KOH solution for 10 hours, wash it with a large amount of deionized water until neutral, perform KOH activation treatment, and then place it in a vacuum and heat it from room temperature to 90 °C at a heating rate of 10 °C per hour, dry it for 18 hours, and then naturally cool it to room temperature to obtain 207.21 g of activated carbonization precursor.

[0056] (7) Preparation of carbon electrode: Place the quartz boat mold carrying the 207.21 g activated carbonization precursor obtained in step (6) into a hot filament chemical vapor deposition equipment. After placement, perform three hydrogen plasma gas replacements in the hot filament chemical vapor deposition equipment to remove oxygen in the system and ensure that the sample is always protected by hydrogen plasma gas during deposition and cooling. Maintain the hydrogen plasma gas at 4 Torr, with an inlet rate of 100 sccm, heat it from room temperature to 400 °C at a heating rate of 5 °C per hour, and deposit at 400 °C under high temperature conditions for 3 hours. Subsequently, after the reduction step, introduce nitrogen plasma (500 W power, 14 Torr N2 gas, 200 sccm flow rate) onto the surface of the carbonization precursor. Heat it from 400 °C to 800 °C at a heating rate of 9 °C per hour and deposit at 800 °C under high temperature conditions for 6 hours. Finally, anneal the sample at 800 °C and cool it to room temperature at a cooling rate of 12 °C per hour. The final product is 181.76 g of carbon electrode, denoted as sample 2.

[0057] The SEM images of sample 1 and sample 2 are as Figure 1 and Figure 2 shown. From the SEM images, the surface morphology of the carbon electrode prepared by the present invention can be seen. Different spherical particles on the surface of the carbon electrode indicate that metal particles with electrocatalytic performance are formed on the surface of the carbon electrode.

[0058] Example 3

[0059] A carbon electrode and its preparation method

[0060] (1) Preparation of polyfurfural resin: Add 100 g of phenol, 137.83 g of furfural, and 155 g of ethanol into a 500 ml reaction flask. Under nitrogen protection, start stirring and preheat to 50 °C. Then add 1.55 g of a compounded basic catalyst (by weight: 0.28 g of potassium hydroxide, 0.15 g of sodium hydroxide, 0.08 g of sodium carbonate, 0.35 g of cetyltrimethylammonium hydroxide, 0.05 g of tetramethylammonium hydroxide, and 0.64 g of water). Raise the reaction temperature to 60 °C and stir for 15 hours, then carry out vacuum desolvation to obtain 235.64 g of brownish-red polyfurfural resin;

[0061] (2) Preparation of polyfurfural resin gel: Take a 500 ml four-necked flask and add 235.64 g of polyfurfural resin, 28.28 g of organosilicon resin adhesive, 7.07 g of thickener polyacrylamide aqueous solution, 14.14 g of initiator potassium persulfate, and 3.77 g of metal active substance palladium diaminodinitrite into the four-necked flask. Stir and mix evenly at room temperature to obtain 288.89 g of brownish-red polyfurfural resin gel.

[0062] (3) Water removal: Drop 0.55 g of tetraethyl orthosilicate into the 288.89 g of brownish-red polyfurfural resin gel obtained in step (2), and further carry out vacuum dehydration. The vacuum dehydration temperature is 75 °C and the vacuum dehydration time is 5 hours, finally obtaining 268.67 g of modified polyfurfural resin gel.

[0063] (4) Curing: Add 8.06 g of curing agent hexamethylenetetramine to the 268.67 g of modified polyfurfural resin gel obtained in step (3), stir and mix evenly at room temperature for crosslinking and curing, then pour it into a mold with dimensions of 500*500*5 mm. Raise the temperature from room temperature to 50 °C at a rate of 8 °C per hour, from 50 °C to 80 °C at a rate of 6 °C per hour, from 80 °C to 100 °C at a rate of 4 °C per hour, from 100 °C to 160 °C at a rate of 2 °C per hour, and keep it at 160 °C for 5 hours to bake off the excess moisture. Finally, demold to obtain 276.13 g of precursor.

[0064] (5) Preparation of carbonization precursor: Place the quartz boat mold carrying the 276.13 g of precursor obtained in step (4) into a muffle furnace. After placement, carry out inert gas replacement three times in the muffle furnace to remove the oxygen in the system and ensure that the sample is always protected by inert gas during carbonization and cooling. Keep the inert gas inlet speed at 2000 sccm (standard cubic centimeters per minute gas flow unit). The precursor is heated from room temperature to 500 °C at a heating rate of 6 °C per hour in an inert atmosphere, carbonized at 500 °C for 5 hours, and then naturally cooled to room temperature to obtain 249.06 g of carbonization precursor.

[0065] (6) Preparation of activated carbon precursor: Soak the 249.06 g of carbon precursor obtained in step (5) in a 3.5 mol / L KOH solution for 10 hours, wash it with a large amount of deionized water until neutral, perform KOH activation treatment, and then place it in a vacuum. Heat it from room temperature to 90 °C at a heating rate of 10 °C per hour, dry it for 14 hours, and then naturally cool it to room temperature to obtain 247.98 g of activated carbon precursor.

[0066] (7) Preparation of carbon electrode: Place the quartz boat mold carrying the 247.98 g of activated carbon precursor obtained in step (6) in a hot filament chemical vapor deposition equipment. After placement, perform hydrogen plasma gas replacement three times inside the hot filament chemical vapor deposition equipment to remove oxygen in the system and ensure that the sample is always protected by hydrogen plasma gas during deposition and cooling. Keep the hydrogen plasma gas at 4 Torr, with an inlet speed of 100 sccm. Heat it from room temperature to 400 °C at a heating rate of 5 °C per hour, and then perform high-temperature deposition at 400 °C for 3 hours. Subsequently, after the reduction step, introduce nitrogen plasma (500 W power, N2 gas at 14 Torr, 200 sccm flow rate) onto the surface of the carbon precursor. Heat it from 400 °C to 800 °C at a heating rate of 8 °C per hour, and then perform high-temperature deposition at 800 °C for 6 hours. Finally, anneal the sample at 800 °C and cool it to room temperature at a cooling rate of 12 °C per hour. The final product is 199.24 g of carbon electrode, denoted as Specimen 3.

[0067] Example 4

[0068] A carbon electrode and its preparation method

[0069] (1) Preparation of polyfurfural resin: Add 100 g of phenol, 142.94 g of furfural, and 160 g of water into a 500 ml reaction flask. Under nitrogen protection, start stirring and preheat to 50 °C, then add 2.01 g of a compound alkaline catalyst (weight ratio: 0.31 g of potassium hydroxide, 0.21 g of sodium hydroxide, 0.13 g of sodium carbonate, 0.41 g of cetyltrimethylammonium hydroxide, 0.08 g of tetramethylammonium hydroxide, and 0.87 g of water). Raise the reaction temperature to 60 °C and stir and react for 15 hours to obtain 241.07 g of brownish-red polyfurfural resin.

[0070] (2) Preparation of polyfurfural resin gel: Take a 500 ml four-necked flask and add 241.07 g of polyfurfural resin, 31.34 g of organosilicon resin adhesive, 8.44 g of thickening agent polyacrylamide aqueous solution, 14.46 g of initiator potassium persulfate, and 3.37 g of metal active substance dinitrodiammine platinum into the four-necked flask. Stir and mix evenly at room temperature to obtain 298.66 g of brownish-red polyfurfural resin gel.

[0071] (3) Water removal: 0.56 g of tetraethyl orthosilicate was dropped into 298.66 g of the brownish-red polyfurfural resin gel obtained in step (2), and further vacuum dehydration was carried out. The vacuum dehydration temperature was 75 °C, and the vacuum dehydration time was 5 hours. Finally, 283.75 g of the modified polyfurfural resin gel was obtained.

[0072] (4) Curing: 8.42 g of hexamethylenetetramine as a curing agent was added to 283.75 g of the modified polyfurfural resin gel obtained in step (3), and the mixture was thoroughly stirred and mixed evenly at room temperature for crosslinking curing. Then it was poured into a mold with dimensions of 500*500*5 mm. It was heated from room temperature to 50 °C at a rate of 8 °C per hour, from 50 °C to 80 °C at a rate of 6 °C per hour, from 80 °C to 100 °C at a rate of 4 °C per hour, and from 100 °C to 160 °C at a rate of 2 °C per hour. It was kept at 160 °C for 5 hours to bake off the excess moisture, and finally the precursor with a mass of 289.26 g was obtained after demolding.

[0073] (5) Preparation of carbonized precursor: The quartz boat mold carrying 289.26 g of the precursor obtained in step (4) was placed in a muffle furnace. After placement, the inside of the muffle furnace was purged with inert gas three times to remove the oxygen in the system, and it was ensured that the sample was always protected by inert gas during carbonization and cooling. The inlet rate of the inert gas was maintained at 2000 sccm (standard cubic centimeters per minute, a unit of gas flow rate). The precursor was heated from room temperature to 500 °C at a heating rate of 6 °C per hour in an inert atmosphere, carbonized at 500 °C for 5 hours, and then naturally cooled to room temperature to obtain 263.04 g of the carbonized precursor.

[0074] (6) Preparation of activated carbonized precursor: 263.04 g of the carbonized precursor obtained in step (5) was soaked in a 3.6 mol / L KOH solution for 10 hours, washed with a large amount of deionized water until neutral, and subjected to KOH activation treatment. Then it was placed in a vacuum and heated from room temperature to 90 °C at a heating rate of 10 °C per hour, dried for 14 hours, and then naturally cooled to room temperature to obtain 262.85 g of the activated carbonized precursor.

[0075] (7) Preparation of carbon electrode: Place the quartz boat mold carrying 262.85 g of the active carbonization precursor obtained in step (6) into a hot wire chemical vapor deposition equipment. After placement, perform hydrogen plasma gas replacement three times inside the hot wire chemical vapor deposition equipment to remove oxygen in the system and ensure that the sample is always protected by hydrogen plasma gas during deposition and cooling. Keep the hydrogen plasma gas at 4 Torr, with an inlet speed of 100 sccm. At a heating rate of 5 °C per hour, raise the temperature from room temperature to 400 °C, and then perform high-temperature deposition at 400 °C for 3 hours. Subsequently, after the reduction step, introduce nitrogen plasma (500 W power, N2 gas at 14 Torr, 200 sccm flow rate) onto the surface of the carbonization precursor. At a heating rate of 8 °C per hour, raise the temperature from 400 °C to 800 °C, and then perform high-temperature deposition at 800 °C for 6 hours. Finally, anneal the sample at 800 °C and cool it to room temperature at a cooling rate of 12 °C per hour. The final product is 209.43 g of carbon electrode, denoted as specimen 4.

[0076] Comparative Example 1

[0077] The difference between this Comparative Example 1 and Example 1 lies in the change of the solid step temperature.

[0078] Add 8.42 g of hexamethylenetetramine as a curing agent to 260 g of modified polyfurfural resin gel, stir and mix evenly at room temperature for crosslinking and curing, and then pour it into a mold with dimensions of 500*500*5 mm. Raise the temperature from room temperature to 50 °C at 20 °C per hour, from 50 °C to 80 °C at 15 °C per hour, from 80 °C to 100 °C at 10 °C per hour, and from 100 °C to 160 °C at 12 °C per hour. Keep it at 160 °C for 1 hour, bake to remove excess moisture, and finally demold to obtain 267.33 g of precursor.

[0079] During the entire curing process of the precursor prepared by the curing curve of this comparative example, there are two changes: gasification and polycondensation. Before 80 °C, it is mainly the gasification stage, which is endothermic. As the temperature rises, small molecule compounds such as the original solvent and water in the modified polyfurfural resin gel system absorb a certain amount of energy and start to escape from the modified polyfurfural resin gel. After 80 °C, it is mainly the polycondensation stage, which is exothermic. As the temperature rises, the activation energy required for the polycondensation reaction is reached, and the modified polyfurfural resin gel system starts to undergo condensation polymerization and releases the gas and heat generated by the reaction. From the two changes of gasification and polycondensation, the heating rate needs to be controlled. If the heating rate is too slow, it will cause waste of energy.

[0080] If the heating rate is too fast, during the gasification process, a large amount of gas escapes, causing the sample to foam or a hardening film to form rapidly on the surface. Small molecule compounds do not have enough time to diffuse and are trapped inside the modified polyfurfural resin gel system, increasing the porosity and decreasing the density of the product. In the polycondensation reaction, due to the fast reaction rate, the release of heat and gas is too concentrated, forming internal stress within the modified polyfurfural resin gel system, which easily causes cracks and defects in the resin and reduces its strength.

[0081] In this comparative example compared with Example 1, the heating rate is greatly accelerated, and the prepared precursor has the phenomenon of surface foaming, as Figure 4 shown.

[0082] Therefore, to obtain a good cured product, the overall heating time should be controlled to be more than 36 hours. This is to allow sufficient time for small molecules and impurity small molecules in the modified furfural resin to escape, resulting in a bubble-free and tightly structured cured product.

[0083] Comparative Example 2

[0084] The difference between this Comparative Example 2 and Example 1 lies in the change in the mold thickness in step (4)

[0085] Curing: Add 6.09 g of hexamine as a curing agent to 263.41 g of the modified polyfurfural resin gel obtained in step (3), stir well at room temperature to mix evenly for crosslinking curing, and then pour it into a mold with dimensions of 500*500*10 mm. Heat from room temperature to 50 °C at a rate of 8 °C per hour, from 50 °C to 80 °C at a rate of 6 °C per hour, from 80 °C to 100 °C at a rate of 4 °C per hour, from 100 °C to 160 °C at a rate of 2 °C per hour, and hold at 160 °C for 5 hours to bake off excess moisture, and finally demold to obtain 262.12 g of the precursor.

[0086] There are a large number of bubbles at the bottom of the precursor prepared in this comparative example. The main reason is that during the entire curing process of the precursor prepared with the curing curve of this comparative example, as the temperature rises, small molecules and impurity molecules escape from the modified polyfurfural resin gel system. However, as the mold thickness increases, the thickness of the precursor also increases accordingly, and the porosity of the obtained precursor also increases correspondingly. Because the thicker the thickness, the more difficult it is for small molecules and impurity molecules to escape from the resin, and the easier it is to generate bubbles during curing.

[0087] Carbon electrode performance test:

[0088] 1. Detection of electrolysis effect

[0089] The dimethyl sebacate electrolysis test was carried out on the sample 2 prepared by the present invention. The specific experimental steps are as follows:

[0090] After mixing 80 g of methyl adipate, 80 g of ethanol, and 15 g of triethylamine evenly, transfer them to an electrolytic cell. The anode of the electrolytic cell uses Specimen 2 prepared by the present invention, and the cathode uses Specimen 2 prepared by the present invention. Then, heat the electrolytic cell to 80 °C and start the electrolysis reaction. The current density of the electrolytic cell is 1500 A / m 2 .

[0091] In the experiment, it was found that the electrolysis current was relatively stable. The electrolysis time was 3 days, the current remained at about 0.3 A, the mass was maintained at 0.62 g, with almost no reduction, and the corrosion was not obvious.

[0092] Using Specimen 2 prepared by the present invention to verify its electrolysis effect, it has been electrolyzed for 439.4 hours, approximately 18.3 days, and it is the seventeenth batch. The mass has decreased by 0.3667 g, a decrease of 49.12% of the total mass. The mass change trend is as follows:

[0093] Electrolysis batch Electrolysis time / h Mass / g 1 18.5 0.7465 2 14.7 0.7212 3 21 0.7020 4 19 0.6820 5 17 0.6682 6 13.5 0.6534 7 12 0.6314 8 17.6 0.6250 9 18.2 0.6201 10 18.1 0.5928 11 19.6 0.5745 12 16.2 0.5603 13 16.8 0.5436 14 19 0.5321 15 17 0.5151 16 17 0.5033 17 22.2 0.4870 18 15.2 0.4751 19 16 0.4567 20 20.1 0.4460 21 16 0.4300 22 18.6 0.4200 23 17.5 0.4035 24 20.55 0.3948 25 18.05 0.3798

[0094] During the electrolysis process, the current density basically remained unchanged, staying at 1500 A / m 2 or so, with stable use effect and high electrical conductivity and electrocatalytic performance.

[0095] 2. Detection of the residual carbon rate:

[0096] Carbonize the modified furfural resin and measure its residual carbon rate, mainly by thermogravimetric analysis (TGA). This method determines the amount of residual carbon by measuring the weight change of the resin under specific temperature and atmosphere. The specific steps are as follows: Put the modified furfural resin samples prepared in step (4) of Examples 1-4 into a thermogravimetric instrument and set the measurement parameters. Start the test and record the curve, which shows the mass reduction of the sample over time. Determine the residual carbon percentage of the resin according to the minimum value in the curve. The experimental data are shown in Table 1

[0097]

[0098]

[0099] As can be seen from the table, Specimen 4 has a higher residual carbon rate and better carbonization effect.

[0100] It should be noted that, in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0101] It should be noted that the above content only illustrates the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a carbon electrode material, characterized in that: The following steps are involved: S1, adding phenol, furfural, solvent and composite alkaline catalyst into a reaction device, heating and stirring to 60-70° C., and reacting for 5-20 hours to obtain a brownish red polyfurfural resin; S2, adding polyfurfural resin, adhesive, thickener, initiator, and metal active substance into a reaction device, stirring and mixing at room temperature to obtain a brown-red polyfurfural resin gel; S3, adding tetraethyl orthosilicate dropwise into the polyfurfural resin gel, placing the mixture on a rotary evaporator to remove moisture, heating the mixture, and performing decompression dehydration to finally obtain a modified polyfurfural resin gel; S4, adding a curing agent, hexamethylenetetramine, to the modified polyfurfural resin gel, stirring and mixing the mixture at room temperature to crosslink and cure the mixture, then pouring the mixture into a mold, slowly heating the mixture, baking the mixture to remove excess water, and demolding the mixture to obtain a precursor; S5, placing the quartz boat mold containing the precursor in a muffle furnace, replacing the inert gas in the muffle furnace three times, and carbonizing at 500° C. in an inert atmosphere to obtain a carbonized precursor; S6, soaking the carbonized precursor in a KOH solution for 10 hours, washing with deionized water until neutral, and then slowly heating to 85-90° C. in a vacuum to dry, to obtain an activated carbonized precursor; S7. Place the quartz boat mold carrying the activated carbonized precursor in a hot wire chemical vapor deposition device, perform hydrogen plasma gas replacement three times, and then perform high-temperature deposition to obtain a carbon electrode material.

2. The method for preparing a carbon electrode material according to claim 1, characterized in that: In step S1, the molar ratio of phenol, furfural and composite alkaline catalyst is 1:1.2-1.5:0.02-0.05; the mass ratio of phenol to solvent is 1:1-2.

3. The method for preparing a carbon electrode material according to claim 1, characterized in that: In step S1, the composite alkaline catalyst is prepared by composite potassium hydroxide, sodium hydroxide, sodium carbonate, hexadecyltrimethylammonium hydroxide, tetramethylammonium hydroxide and water in a mass ratio of 1:0.5-1:0.1-0.5:1-1.5:0.1-0.5:2-3; the solvent is one or more of water, methanol and ethanol.

4. The method for preparing a carbon electrode material according to claim 1, characterized in that: In step S2, the mass ratio of the polyfurfural resin, the adhesive, the thickener, the initiator, and the metal active substance is 1: 0.08-0.15: 0.01-0.05: 0.03-0.1: 0.01-0.

02.

5. The method for preparing a carbon electrode material according to claim 5, characterized in that: The adhesive is a silicone resin adhesive, the thickener is a polyacrylamide aqueous solution or a sodium polyacrylate aqueous solution; the initiator is one or more of potassium persulfate, ammonium persulfate and sodium persulfate; and the metal active substance is dinitrosodiammineplatinum or dinitrosodiamminepalladium.

6. The method for preparing a carbon electrode material according to claim 1, characterized in that: In step S3, the mass ratio of the polyfurfural resin gel to tetraethyl orthosilicate is 1:0.01-0.04, the temperature of the reduced pressure dehydration is 60-85° C., and the time of the reduced pressure dehydration is 1-5 hours.

7. The method for preparing a carbon electrode material according to claim 1, characterized in that: In step S4, the mass ratio of the modified furfural resin gel to the curing agent hexamethylenetetramine is 1:0.02-0.05; the specific conditions for baking are: from room temperature to 50°C at 5-10°C / hour, from 50°C to 80°C at 4-8°C / hour, from 80°C to 100°C at 3-5°C / hour, from 100°C to 160°C at 1-3°C / hour, and maintained at 160°C for 1-10 hours.

8. The method for preparing a carbon electrode material according to claim 1, characterized in that: In step S7, the specific conditions for high-temperature deposition are as follows: maintaining the hydrogen plasma gas at 4Torr, with an intake rate of 100sccm, heating from room temperature to 400°C at a heating rate of 2 to 5°C / hour, and then high-temperature deposition at 400°C for 3 to 10 hours. Subsequently, nitrogen plasma is introduced into the surface of the carbonized precursor; heating from 400°C to 800°C at a heating rate of 8 to 10°C / hour, and then high-temperature deposition at 800°C for 6 to 12 hours. Finally, the sample is annealed at 800°C, and cooled to room temperature at a cooling rate of 10 to 12°C / hour to obtain a carbon electrode material.

9. A carbon electrode material prepared by the preparation method according to any one of claims 1 to 9.

10. Use of the carbon electrode material according to claim 9 in electrochemical synthesis.

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