Multifunctional composite anti-corrosion cyanobacteria carbon material electrode and preparation method and application thereof

Abstract

The application discloses a multifunctional anti-corrosion blue-green algae carbon material electrode and a preparation method and application thereof, and belongs to the field of electrode materials. The application takes blue-green algae carbon material as a core. The cell structure of blue-green algae is naturally provided with a multistage pore structure, and can be converted into hierarchical porous carbon after pyrolysis, which is beneficial to in-situ nitrogen doping, has a large specific surface area, high electrochemical activity, and strong conductivity. The wettability of the carbon felt gap is improved by increasing the gap. Meanwhile, through three paths of improving anchoring capacity by KOH surface chemical modification, maintaining organic acid obtained by carbon fixation by compounding Co3O4 slurry and precisely loading active components, and constructing and cross-linking double protective layers, the uniform distribution of functional materials, the dense and firm protective layer, and the reservation of electrode conductivity are unified, and finally, a long-acting composite electrode suitable for the electrolyte environment of a carbon fixation photovoltaic flow battery is prepared.

Description

Technical Field

[0001] This invention belongs to the field of electrode materials, specifically relating to a multifunctional composite corrosion-resistant cyanobacteria carbon material electrode, its preparation method, and its application. Background Technology

[0002] In new energy electrochemical devices (such as fuel cells), carbon felt, as a key electrode material, is widely used as a gas diffusion layer or catalyst support due to its high specific surface area, good conductivity, and porous structure. However, carbon felt still has its material limitations.

[0003] First, when carbon felt is used as an electrode carrier, the lack of chemical anchors on its surface makes it difficult to load functional materials. Active components (such as catalysts and preservatives) can only be loaded through physical adsorption, resulting in generally low loading levels and difficulty in uniformly penetrating into the gaps between carbon felt fibers. Traditional protective coatings are only bonded to carbon felt by van der Waals forces, leading to poor adhesion and interfacial voids due to hydrophobicity. Long-term use can cause blistering and peeling of the protective layer, which in turn fails to prevent the penetration of corrosive ions. These problems point to the inherent inertness of the carbon felt surface, ultimately resulting in low electrode loading and short lifespan, limiting its application in long-term service scenarios such as energy storage and catalysis. Furthermore, loading other supplementary materials or protective layers can cause the conductivity of the electrode material to be far lower than expected.

[0004] Secondly, the porous nature of carbon felt makes it susceptible to severe electrochemical corrosion during long-term operation in highly corrosive electrolytes. The mechanism involves corrosive ions penetrating through the pores and reacting with the carbon matrix, leading to electrode structure damage and a series of other problems, ultimately resulting in decreased device efficiency and shortened lifespan. To address this challenge, existing technologies mainly focus on material modification, but all have significant limitations. Insulating barrier coatings (such as epoxy resin and ceramic coatings) achieve corrosion protection through physical isolation, but the high insulation of the material itself sacrifices electrode conductivity. Metal plating combines corrosion protection and conductivity, but it is not only costly and complex, but the coating is also prone to peeling, thus accelerating localized corrosion. Other conductive polymer coatings (such as polypyrrole and polythiophene) can theoretically achieve dual functions, but they have poor stability in strong acid / alkali environments, and the polymerization process makes it difficult to form a dense, defect-free film. Therefore, traditional technical approaches still struggle to balance the four dimensions of "efficient corrosion protection," "conductivity retention," "long-term stability," and "economic feasibility."

[0005] Therefore, developing a novel coating material that can synergistically optimize the surface activation, hydrophobicity, corrosion resistance, and conductivity of carbon felt has become a technical challenge to be overcome in the field of electrode materials. Summary of the Invention

[0006] To address the aforementioned defects and shortcomings, this invention provides a multifunctional composite corrosion-resistant cyanobacteria carbon material electrode, its preparation method, and its application.

[0007] The technical solution of the present invention is as follows: One objective of this invention is to provide a method for preparing a multifunctional composite corrosion-resistant cyanobacterial carbon material electrode, wherein the preparation method of the multifunctional composite corrosion-resistant cyanobacterial carbon material is carried out according to the following steps: S1: Pretreatment operations such as introducing polar groups to activate and increase the loading of carbon felt and drying are performed. S2: The cyanobacteria are ultrasonically crushed, centrifuged, and dried, and finally carbonized in a tube furnace to become cyanobacterial carbon material. Then, the cyanobacterial carbon material is activated and modified with KOH, urea, and ammonia. The carbon felt and cyanobacterial carbon material are placed in a cobalt nitrate solution and ammonia is added dropwise to precipitate them. The mixture is then dried until there is no moisture left. Finally, it is heat-treated in a tube furnace to obtain carbon felt with cyanobacterial carbon material / Co3O4 attached. S3: The carbon felt is placed in an aniline hydrochloride solution using an impregnation coating method, and an ammonium persulfate solution is added dropwise. Finally, a hot pressing operation is performed to form a polyaniline protective coating.

[0008] Further specifying the process for S1, the carbon felt is cut and then ultrasonically cleaned alternately with deionized water and isopropanol (IPA) for 10 minutes each. After cleaning, it is dried. A hydrogen peroxide solution is prepared, and the dried carbon felt is completely immersed in this solution in a water bath. After the reaction is complete, the carbon felt is repeatedly rinsed with a large amount of distilled water, and then dried.

[0009] Furthermore, the first drying temperature in S1 is 80°C, and the drying time is 6 hours in a vacuum oven.

[0010] To further specify, the dilute hydrogen peroxide solution should be prepared with a mass ratio of 30% H2O2 to distilled water of 1:1.

[0011] Furthermore, the water bath immersion temperature is specified as 65℃, and the immersion time is 5 hours.

[0012] Furthermore, the second drying temperature in S1 is 80°C, and the drying time is 12 hours in a vacuum oven.

[0013] Further specifying the specific process for activating and modifying cyanobacterial carbon materials in S2: First, cyanobacterial carbon is pulverized to less than 100 mesh; then KOH and KNO3 are dissolved in 80 mL of distilled water, cyanobacterial carbon is added, stirred at room temperature for 90-120 min, dried at 90℃ for 14 h, heated to 700℃ under N2 protection for 2 hours, and finally washed with hydrochloric acid and distilled water, and dried for 12 hours.

[0014] Further specify the centrifugation parameters for cyanobacteria in S2: 5500 rpm for 5 minutes.

[0015] Further specifying, the cyanobacteria drying process in S2 involves placing the algae in a drying oven at 65°C for 5 hours.

[0016] Further specified, the carbonization temperature of cyanobacteria in the S2 tubular furnace is 550℃, and the carbonization time is 2 hours.

[0017] Further specifying, the activation mass ratio in S2 is: cyanobacterial carbon material: KOH: KNO3 = 5:10:1 Further specifying, the concentration of cobalt nitrate solution in S2 is 1 mol / L.

[0018] Further specify that ammonia water is added dropwise to S2 until the solution pH reaches 9-10.

[0019] Further specifying, the soaking time in S2 is 6 hours.

[0020] Further specified, the drying temperature in S2 is 80°C, and a vacuum is applied for 12 hours.

[0021] Further specified, the heat treatment temperature of the S2 tubular furnace is 300℃, and the treatment time is 2 hours.

[0022] Further specified, the concentration of aniline hydrochloride solution in S3 is 0.1 mol / L, and the soaking time is 30 min.

[0023] Further restrictions are imposed: the concentration of persulfate solution in S3 is 0.1 mol / L, and the ice bath temperature is 0-5℃.

[0024] Further specified, the hot pressing temperature in S3 is 130℃, the pressure is 1 MPa, and the time is 45 min.

[0025] The second objective of this invention is to provide a multifunctional composite corrosion-resistant cyanobacterial carbon material electrode prepared by the above method. The multifunctional composite cyanobacterial carbon material electrode is a composite material constructed from biomass carbon material extracted from cyanobacteria, cobalt tetroxide, and a polyaniline (PANI) protective layer with modified carbon felt as the substrate.

[0026] The third objective of this invention is to provide an application of the multifunctional composite corrosion-resistant cyanobacterial carbon material electrode prepared by the above method in photovoltaic carbon fixation cells.

[0027] The advantages of this invention compared to the prior art are: (1) The present invention first activates the carbon felt to introduce hydroxyl and carboxyl groups to form chemical bonds and anchor it, thereby increasing its own loading capacity. The maximum loading capacity of cobalt tetroxide that can be achieved by this electrode exceeds that of commercially available carbon felt electrodes.

[0028] (2) The present invention uses biomass carbon material made from cyanobacteria. Because the porous structure naturally present in cyanobacteria cells has a high porosity after carbonization, it can provide more reaction sites for battery reaction, improve electron transport efficiency and conductivity. Moreover, the double-sided PANI protective layer formed by hot pressing has high mechanical strength and can effectively isolate the corrosive effect of external electrolyte. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the preparation process of the multifunctional composite corrosion-resistant cyanobacteria carbon material electrode of the present invention. Figure 2 These are SEM images of the cyanobacterial carbon material of the present invention (left image 5μm, right image 10μm). Figure 3 These are the contact angle test results for commercial carbon felt. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0032] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used in the following embodiments, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0033] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all subranges contained therein.

[0034] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of occurrences) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0035] Example 1: The preparation method of the multifunctional composite corrosion-resistant cyanobacteria carbon material electrode in this embodiment is carried out according to the following steps: Step 1: Carbon felt pretreatment and surface activation: First, take commercial carbon felt and cut it into 50mm×50mm×5mm square pieces using scissors. Place the cut carbon felt in a cleaning tank, add deionized water and isopropyl alcohol (IPA), and clean it alternately in an ultrasonic cleaner for 10 minutes. Then, the cleaned carbon felt was transferred to a vacuum oven and dried at 80°C for 6 hours. After drying, 100 mL of 30% hydrogen peroxide solution was taken, and 100 mL of distilled water was added to adjust the pH to neutral (pH≈7). The dried carbon felt was then completely immersed in the solution and placed in a constant temperature water bath at 65°C for 5 hours. Finally, remove the carbon felt, rinse it repeatedly with plenty of deionized water until the pH is close to neutral, and then place it in a vacuum oven at 80°C for 12 hours to dry.

[0036] Step 2: Carbon felt loading material (cyanobacteria carbon material / Co3O4): First, take 20g of pre-prepared cyanobacterial porous carbon (sieved through 200-400 mesh), add it to 200 mL of 1.0 mol / L cobalt nitrate (Co(NO3)2·6H2O) solution, and stir continuously for 30 minutes using a magnetic stirrer; Then, while continuously stirring, ammonia water was slowly added dropwise until the solution pH reached 9-10, and stirring was maintained for 1 hour, so that Co 2+ A uniform cobalt hydroxide (Co(OH)2) is formed on the surface of the cyanobacterial carbon. The pretreated carbon felt is placed in a vacuum drying oven at 80°C and dried for 12 hours to remove residual moisture. Then, a cyanobacterial carbon slurry containing Co(OH)2 is uniformly poured onto the surface of the carbon felt, and a scraper or spraying method is used to ensure that the slurry penetrates into the fiber gaps. Subsequently, the carbon felt sample impregnated with slurry was transferred to a high-temperature resistant ceramic boat and placed in a tube furnace. The program was set as follows: first, the temperature was increased to 300℃ at a rate of 5℃ / min; then, it was kept at 300℃ for 2 hours, and then naturally cooled to room temperature before being removed.

[0037] Step 3: Constructing the polyaniline (PANI) protective layer: First, immerse the electrode in a 0.1 mol / L aniline hydrochloride solution (0-5℃ ice bath), and slowly add an equal volume of 0.1 mol / L ammonium persulfate (APS) oxidant solution while stirring continuously for 2 hours; Then, the PANI-coated electrode is hot-pressed at a temperature of 120-150℃ and a pressure of 0.5-1.0 MPa for 30-60 minutes to obtain a multifunctional composite corrosion-resistant cyanobacteria-carbon material electrode. Comparative Example 1: Commercial carbon felt.

[0038] Comparative Example 2: The composite electrode preparation method of this comparative example is carried out according to the following steps: First, take 20g of pre-prepared porous carbon of cyanobacteria (sieved through a 200-400 mesh screen), add it to 200mL of distilled water, and stir continuously for 30 minutes using a magnetic stirrer; Then, the blue-green algae carbon slurry is evenly poured onto the surface of the carbon felt, and a scraper or spraying method is used to ensure that the slurry penetrates into the fiber gaps. Finally, the carbon felt sample impregnated with slurry was transferred to a high-temperature resistant ceramic boat and placed in a tube furnace. The program was set as follows: first, the temperature was increased to 300℃ at a rate of 5℃ / min; then, it was kept at 300℃ for 2 hours, and after naturally cooling to room temperature, it was removed, resulting in a carbon felt electrode with attached cyanobacteria carbon material.

[0039] Comparative Example 3: The composite electrode preparation method of this comparative example is carried out according to the following steps: First, take 20g of pre-prepared cyanobacterial porous carbon (sieved through a 200-400 mesh) and add it to 200 mL of 1.0 mol / L cobalt nitrate (Co(NO3)2·6H2O) solution. Stir continuously for 30 minutes using a magnetic stirrer. Then, while continuously stirring, ammonia water was slowly added dropwise until the solution pH reached 9-10, and stirring was maintained for 1 hour, so that Co 2+ A uniform cobalt hydroxide (Co(OH)2) is formed on the surface of the cyanobacterial carbon. The pretreated carbon felt is placed in a vacuum drying oven at 80°C and dried for 12 hours to remove residual moisture. Then, a cyanobacterial carbon slurry containing Co(OH)2 is uniformly poured onto the surface of the carbon felt, and a scraper or spraying method is used to ensure that the slurry penetrates into the fiber gaps. Finally, the carbon felt sample impregnated with slurry was transferred to a high-temperature resistant ceramic boat and placed in a tube furnace. The program was set as follows: first, the temperature was increased to 300℃ at a rate of 5℃ / min; then, it was kept at 300℃ for 2 hours, and after naturally cooling to room temperature, it was removed, resulting in a carbon felt electrode with attached cyanobacteria carbon material / Co3O4.

[0040] The contact angle measurement results for different electrode materials are shown in Table 1 and Figure 3 As shown, the results indicate that Comparative Example 1 (commercial carbon felt) has a hydrophobic surface, while after modifying the surface of the carbon felt material using the method of this patent, the composite electrode surfaces can achieve instantaneous wetting (similar to superhydrophilicity, contact angle <0°), indicating a significant improvement in electrode wettability. Electrolyte absorption tests were conducted on different composite electrode materials capable of instantaneous wetting, and the results are shown in Table 2. The results show that after various surface modification processes, the electrolyte content that the electrode materials can absorb is increased, thus proving that this scheme can effectively promote the transfer process on the electrode surface and is expected to promote an increase in reaction rate.

[0041] Table 1. Contact angle measurement results for different electrode materials

[0042] Table 2. Electrolyte absorption test results for different composite electrode materials

[0043] The above description is merely a preferred embodiment of the present invention. These specific embodiments are different implementations based on the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a multifunctional composite corrosion-resistant cyanobacteria carbon material electrode, characterized in that, Follow these steps: S1: Pretreatment operations such as introducing polar groups to activate and increase the loading of carbon felt and drying are performed. S2: The cyanobacteria are ultrasonically crushed, centrifuged, dried, and finally carbonized in a tube furnace to become cyanobacterial carbon material. The carbon felt and cyanobacterial carbon material are placed in a cobalt nitrate solution and ammonia is added dropwise to precipitate them. They are then dried until there is no moisture. Finally, they are heat-treated in a tube furnace to obtain carbon felt with cyanobacterial carbon material / Co3O4 attached. S3: The carbon felt is placed in an aniline hydrochloride solution using an impregnation coating method, and an ammonium persulfate solution is added dropwise. Finally, a hot pressing operation is performed to form a polyaniline protective coating.

2. The method according to claim 1, characterized in that, The specific process of S1 is as follows: After cutting the carbon felt, it is ultrasonically cleaned alternately with deionized water and isopropanol (IPA) for 10 minutes each. After cleaning, it is dried. First, a hydrogen peroxide solution is prepared. The dried carbon felt is completely immersed in the above solution and soaked in a water bath. After the reaction is completed, the carbon felt is repeatedly rinsed with a large amount of distilled water and then dried.

3. The method according to claim 2, characterized in that, Centrifugation parameters for cyanobacteria: 5500 rpm, centrifugation time 5 minutes, and finally add ammonia water until the solution pH reaches 9-10.

4. The method according to claim 1, characterized in that, The cyanobacteria drying process involves placing them in a drying oven at 65°C for 5 hours.

5. The method according to claim 1, characterized in that, The carbonization temperature of cyanobacteria in the S2 tube furnace is 550℃, and the carbonization time is 2 hours.

6. The method according to claim 1, characterized in that, The concentration of cobalt nitrate solution in S2 is 1 mol / L.

7. The method according to claim 1, characterized in that, The heat treatment temperature of the S2 tubular furnace is 300℃, and the treatment time is 2 hours.

8. The method according to claim 1, characterized in that, In S3, the concentration of aniline hydrochloride solution is 0.1 mol / L, the soaking time is 30 min, the concentration of ammonium persulfate (APS) solution is 0.1 mol / L, the ice bath temperature is 0-5℃, the hot pressing temperature is 130℃, the pressure is 1 MPa, and the time is 45 min.

9. The multifunctional composite corrosion-resistant cyanobacterial carbon material electrode prepared by the method of any one of claims 1-8, wherein the multifunctional composite cyanobacterial carbon material electrode is a composite material constructed from biomass carbon material extracted from cyanobacteria, cobalt tetroxide, a polyaniline (PANI) protective layer, and a modified carbon felt as a substrate.

10. The application of the multifunctional composite corrosion-resistant cyanobacterial carbon material electrode prepared by the method of any one of claims 1-8 in carbon fixation in flow batteries.

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