An oxygen electrocatalyst based on biomass-derived materials and a method for preparing the same

Abstract

The application provides an oxygen electrocatalyst based on biomass-derived materials and a preparation method thereof, and the preparation method specifically comprises the following steps: S1, preparing a staphylococcus aureus sample containing Co; S2, dispersing the staphylococcus aureus sample prepared in step S1 as a biomass template in a methanol solution containing Co 2+ , Zn 2+ and Mn 2+ to obtain solution A; S3, dissolving 2-methylimidazole in methanol to obtain solution B; S4, mixing solution A and solution B, and then performing stirring reaction and centrifugation to obtain a semi-finished product; and S5, performing pyrolysis reaction on the semi-finished product obtained in step S4 to obtain an oxygen electrocatalyst. Compared with the prior art, the application combines the advantages of biomass materials, selects staphylococcus aureus as a biomass template, constructs the microstructure and intrinsic catalytic active sites in a self-assembly manner, prepares a hollow spherical self-supporting oxygen electrocatalyst (MnO2 / Co2P@SDHC) loaded with MnO2 / Co2P heterostructures in a near-micron scale, realizes excellent catalytic performance, and has super-high stability and methanol resistance.

Description

Technical Field

[0001] This invention belongs to the field of energy storage materials technology, specifically relating to an oxygen electrocatalyst based on biomass-derived materials and its preparation method. Background Technology

[0002] Metal-based catalysts, such as Pt / C, are widely used as standard catalysts due to their excellent ORR catalytic activity, and can effectively enhance the kinetics of the cathode reaction.

[0003] However, the large-scale application and sustainability of Pt / C are limited by its high cost, limited methanol tolerance, and insufficient stability. Biomass materials are natural precursors for a class of green and renewable carbon-based catalysts, characterized by their wide distribution in nature, ordered structure, and abundance of heteroatoms. However, their large size and rigid bulk structure limit the full utilization of their microscopic advantages. In contrast, microorganisms, such as bacteria with near-micron-specific macroscopic structures, are perfect biomass templates for oxygen electrocatalysts. By modifying them, highly efficient intrinsic catalytic activity can be obtained while inheriting the biomass structure. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an oxygen electrocatalyst based on biomass-derived materials and its preparation method, thereby overcoming the shortcomings of existing technologies.

[0005] This invention provides an oxygen electrocatalyst based on biomass-derived materials. The oxygen electrocatalyst is a Co2P hollow spherical nanoparticle containing a heterojunction interface composed of MnO2 clusters, with a rough surface that has multiple undulations and a diameter of 1±0.2 μm.

[0006] Compared with existing technologies, this method generates Co2P nanoparticles with high ORR activity in situ from P and Co in the phospholipid bilayer, and synergistically enhances intrinsic reaction kinetics with the heterojunction interface composed of MnO2 clusters; the irregular hollow spherical structure can create a microenvironment conducive to ORR mass transfer efficiency near the electrode, the catalyst structure is clear, and it has ultra-high stability and methanol resistance.

[0007] A second objective of this invention is to provide a method for preparing an oxygen electrocatalyst, the method specifically comprising the following steps:

[0008] S1. Prepare Staphylococcus aureus samples containing Co;

[0009] S2. The Staphylococcus aureus sample obtained in step S1 is used as a biomass template and dispersed in a medium containing Co. 2+ Zn 2+ and Mn 2+ Solution A was obtained from the methanol solution;

[0010] S3. Dissolve 2-methylimidazole in methanol to obtain solution B;

[0011] S4. After mixing solutions A and B, the mixture is stirred and centrifuged to obtain a semi-finished product.

[0012] S5. The semi-finished product obtained in step S4 is subjected to pyrolysis reaction to obtain oxygen electrocatalyst.

[0013] Compared with existing technologies, this invention combines the advantages of biomass materials, selects Staphylococcus aureus (S. aureus) as a biomass template, and constructs its microstructure and intrinsic catalytic active sites in a self-assembly manner to prepare a hollow spherical self-supporting oxygen electrocatalyst (MnO2 / Co2P@SDHC) with composite nanoparticles of MnO2 / Co2P heterostructure loaded on the near-micron scale, achieving excellent catalytic performance and exhibiting ultra-high stability and methanol resistance.

[0014] In one possible implementation, step S1 is as follows:

[0015] S11. Staphylococcus aureus was cultured in a culture medium as a biomass material, and bacterial cells were collected by centrifugation after the culture was completed.

[0016] S12. Bacterial cells are mixed in a mixed solvent, and cobalt nitrate solution is added and stirred. The mixture is then centrifuged, washed, and freeze-dried to obtain a Staphylococcus aureus sample containing Co.

[0017] Compared with existing technologies, this invention employs the aforementioned technology, wherein the cell wall and internal structure of Staphylococcus aureus can provide a natural three-dimensional template, facilitating the formation of a catalyst with a specific morphology and structure. By mixing and stirring bacterial cells with a cobalt nitrate solution, Co... 2+ The uniform adsorption of ions on or inside bacterial cells helps ensure the uniform distribution of metal components in the subsequently generated catalyst. Furthermore, by loading metal ions onto bacterial cells, more active sites can be formed after pyrolysis, thereby improving the electrocatalytic activity of the catalyst.

[0018] In one possible implementation, in step S11, the culture medium is Luria Broth medium, the culture method is shaking culture, and the parameters are as follows: temperature is 30°C, speed is 180 rpm, and time is 18 h.

[0019] Compared with existing technologies, the present invention uses the above-mentioned parameters for cultivation, which has the following advantages: LB (Luria Broth) medium is a commonly used bacterial culture medium, rich in protein, carbon source, and other essential nutrients, which can support the rapid growth of Staphylococcus aureus. An 18-hour cultivation time is sufficient for the bacteria to reach a high cell density, while avoiding resource depletion or metabolic product accumulation due to overgrowth. Shaking cultivation (180 rpm) ensures uniform distribution of nutrients and oxygen in the medium, promoting consistent bacterial growth throughout the cultivation process, which helps to obtain a more uniform biological template. 30℃ is one of the ideal temperature ranges for Staphylococcus aureus growth; this temperature is neither too high, causing heat stress, nor too low, affecting the growth rate, helping to maintain the bacteria's optimal physiological state. Cultivating Staphylococcus aureus in LB medium at 30℃ with shaking at 180 rpm for 18 hours can effectively promote the growth of Staphylococcus aureus, providing a high-quality biomass template, thus laying a good foundation for subsequent metal ion adsorption and catalyst preparation.

[0020] In one possible implementation, the specific steps of centrifugation in step S11 are as follows: collect bacterial cells by centrifuging at 5000 rpm for 5 minutes at 4°C, and then washing them three times with sterile deionized water.

[0021] Compared with the prior art, the advantages of the centrifugation steps in this invention are as follows: 5000 rpm is a relatively high centrifugation speed, which can effectively separate bacterial cells from the culture medium, ensuring that the precipitate is mainly bacterial cells, while nutrients and other impurities in the supernatant are removed; 5 minutes is sufficient to complete effective cell precipitation, while avoiding mechanical damage to cells that may be caused by prolonged centrifugation; centrifugation at 4°C helps to maintain the activity and structural integrity of bacterial cells, and low temperature can reduce enzyme activity and prevent the degradation of intracellular components, thereby maintaining the optimal state of the cells.

[0022] In one possible implementation, step S12 is as follows: Staphylococcus aureus powder is dispersed in a mixed solvent of ethanol and sterile deionized water, ultrasonically treated for 30 min, then 0.1 M cobalt nitrate solution is added under stirring, and stirring is continued for 12 hours. After centrifugation and washing, the sample is freeze-dried for 12 h to obtain a Co-containing Staphylococcus aureus sample.

[0023] Compared with existing technologies, the present invention uses the above-mentioned treatment method to obtain Staphylococcus aureus samples containing Co., the advantages of which are: using a mixed solvent of ethanol and sterile deionized water can provide a good dispersion medium, which helps the bacterial cells to be evenly distributed in the solution; 30 minutes of sonication can further break up cell aggregation, ensuring that each cell can fully contact the solvent and improve the uniformity of subsequent metal ion adsorption; adding 0.1M cobalt nitrate solution while stirring and continuing to stir for 12 hours can ensure that the metal ions have enough time to fully contact and adsorb with the surface or interior of the bacterial cells to form a stable complex; the 0.1M cobalt nitrate solution provides an appropriate concentration of metal ions, which will not cause precipitation due to excessive concentration, nor will affect the adsorption effect due to excessively low concentration.

[0024] In one possible implementation, the volume ratio of ethanol to sterile deionized water is 2:1.

[0025] Compared with the prior art, the present invention limits the volumes of ethanol and sterile deionized water to the above range. Ethanol is an organic solvent with certain polarity and solubility, while sterile deionized water is a polar solvent. The mixed solvent with a volume ratio of 2:1 can provide an environment that has both good polarity and certain non-polarity, which helps the bacterial cells to be evenly dispersed in the solution. The presence of ethanol can increase the permeability of the solvent to the cell wall, which helps the cobalt nitrate solution to enter the cell interior better, thereby improving the adsorption efficiency of metal ions.

[0026] In one possible implementation, the specific preparation process of solution A in step S2 is as follows: the Staphylococcus aureus containing Co obtained in step S1, cobalt nitrate, zinc nitrate, manganese acetate and methanol are mixed, and after ultrasonic treatment for 0.5 h, the mixture is stirred for another 1 h.

[0027] Compared with existing technologies, the simultaneous addition of cobalt nitrate, zinc nitrate and manganese acetate can form a multi-metal-doped precursor on the bacterial template, which helps to improve the electrochemical performance of the final catalyst; the synergistic effect between different metal elements can optimize the electron transfer process and improve the catalyst's activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).

[0028] In one possible implementation, the stirring reaction parameters in step S4 are as follows: temperature is room temperature, and time is 5 hours.

[0029] In one possible implementation, the specific steps of the pyrolysis reaction in step S5 are as follows: pyrolysis is carried out in an argon atmosphere at a rate of 5°C / min, first by raising the temperature to 250°C and holding it for 60 min, and then by raising the temperature to 950°C and holding it for 120 min.

[0030] Compared with existing technologies, this invention uses the above-mentioned parameters for the pyrolysis reaction. The advantages of this method are: pyrolysis in an argon atmosphere effectively prevents oxidation of the material at high temperatures, ensuring the purity of the generated carbon-based material and metal nanoparticles; a slow heating rate of 5°C / min reduces thermal stress caused by sudden temperature changes, preventing internal cracks or structural damage; holding the temperature at 250°C for 60 minutes effectively removes moisture, residual organic solvents, and other volatile substances from the sample, creating favorable conditions for subsequent high-temperature pyrolysis; and holding the temperature at 950°C for 120 minutes ensures complete carbonization of the bacterial cell template, forming a stable carbon-based material. This specific pyrolysis process allows for gradual heating in an inert atmosphere, ensuring thorough carbonization and uniform distribution of metal nanoparticles through different temperature ranges, thereby preparing a high-performance oxygen electrocatalyst. Attached Figure Description

[0031] Figure 1 This is a scanning electron microscope image of the MnO2 / Co2P@SDHC catalyst prepared in Example 1;

[0032] Figure 2 LSV plot for ORR test of MnO2 / Co2P@SDHC catalyst. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0034] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters.

[0036] The technical effects of the present invention will be described below with reference to specific embodiments.

[0037] Example 1

[0038] This embodiment provides an oxygen electrocatalyst based on biomass-derived materials, which is prepared by the following method:

[0039] Staphylococcus aureus was cultured in LB (Luria Broth) medium at 30°C with shaking at 180 rpm. After 18 h of culture, bacterial cells were collected by centrifugation at 5000 rpm for 5 min at 4°C. The cells were then washed three times with sterile deionized water. Approximately 0.3 g of Staphylococcus aureus powder was dispersed in a mixture of 60 mL of ethanol and sterile deionized water (ethanol:sterile deionized water = 2:1, v / v). The mixture was sonicated for 30 min, and then 10 mL of 0.1 M cobalt nitrate solution was added with stirring. Stirring was continued for 12 h. After several centrifugations and washings, the sample was freeze-dried for 12 h to obtain a Co-containing Staphylococcus aureus sample.

[0040] 50 mg of prepared Staphylococcus aureus containing Co, 0.0989 g of cobalt nitrate, 0.1 g of zinc nitrate, and 0.05 g of manganese acetate were dispersed in 20 mL of methanol, sonicated for 0.5 h, and then stirred for 1 h to form solution A.

[0041] Dissolve 1.845 g of 2-Melm in 45 mL of methanol to form a solution;

[0042] Solution A was mixed with solution B and stirred at low speed for 5 hours at room temperature. The sample CoZnMn-ZIF67@S.aureus was obtained by centrifugation, washed several times, and dried overnight in a vacuum oven.

[0043] The sample CoZnMn-ZIF67@S.aureus was pyrolyzed in an argon atmosphere at a rate of 5 °C / min. It was first held at 250 °C for 60 minutes to maintain its spherical structure, and then heated to 950 °C and held for 120 minutes to obtain the sample MnO2 / Co2P@SDHC.

[0044] The oxygen electrocatalyst prepared in this embodiment was observed, and its scanning electron microscope image is shown below. Figure 1 As shown, from Figure 1 As can be seen, the golden grapes have a rough, multifaceted surface with a diameter of approximately 1 μm.

[0045] Example 2

[0046] 5 mg of the oxygen electrocatalyst prepared in Example 1, 500 μL of ethanol, and 30 μL of Nafion solution were ultrasonically mixed to form a homogeneous catalyst ink. 10 μL of this oxygen electrocatalyst ink was then uniformly drop-coated onto the surface of a rotating disk ring electrode and allowed to dry naturally at room temperature. Using Ag / AgCl as the reference electrode and a carbon rod as the counter electrode, the ORR was measured in oxygen-saturated 0.1 M KOH. The resulting LSV curve is shown below. Figure 2 As shown, the half-wave potential is 0.83V, and the initial potential is 0.95V.

[0047] As can be seen from the above results, this invention combines the advantages of biomass materials, selects Staphylococcus aureus (S. aureus) as a biomass template, and constructs its microstructure and intrinsic catalytic active sites in a self-assembly manner to prepare a hollow spherical self-supporting oxygen electrocatalyst (MnO2 / Co2P@SDHC) with composite nanoparticles of MnO2 / Co2P heterostructure loaded on the near-micron scale, achieving excellent catalytic performance and exhibiting ultra-high stability and methanol resistance.

[0048] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A biomass-derivative material-based oxygen electrocatalyst, characterized by, The oxygen electrocatalyst is Co2P hollow spherical nanoparticles, and contains a heterojunction interface composed of MnO2 clusters, has a rough surface with multi-faceted undulations, and has a diameter of 1±0.2um.

2. The method of making an oxygen electrocatalyst of claim 1, wherein, The preparation method specifically comprises the following steps: S1, preparing a Staphylococcus aureus sample containing Co; S2, the staphylococcus aureus sample prepared in step S1 is dispersed in a methanol solution containing Co 2+ , Zn 2+ and Mn 2+ to obtain solution A; S3, dissolving 2-methylimidazole in methanol to obtain solution B; S4, mixing solution A and solution B, and then performing stirring reaction and centrifugation to obtain a semi-finished product; S5, performing pyrolysis reaction on the semi-finished product obtained in step S4 to obtain an oxygen electrocatalyst.

3. The production method according to claim 2, wherein The step S1 is as follows: S11, culturing Staphylococcus aureus as biomass material in a culture medium, and collecting bacterial cells by centrifugation after the culture is completed; S12, mixing the bacterial cells in a mixed solvent, adding a cobalt nitrate solution for stirring treatment, and then sequentially performing centrifugation, washing and freeze-drying treatment to obtain a Staphylococcus aureus sample containing Co.

4. The production method according to claim 3, wherein In the step S11, the culture medium is Luria Broth culture medium, and the culture is performed by oscillation culture, and the parameters are as follows: temperature is 30℃, speed is 180rpm, and time is 18h.

5. The production method according to claim 3, wherein In the step S11, the specific steps of centrifugation are as follows: collect the bacterial cells by centrifugation at a speed of 5000rpm for 5min at 4℃, and then wash with sterile deionized water for 3 times.

6. The production method according to claim 3, wherein The specific steps of the step S12 are as follows: disperse the Staphylococcus aureus powder in a mixed solvent of ethanol and sterile deionized water, ultrasonic treatment for 30min, then add 0.1M cobalt nitrate solution under stirring, and continue stirring for 12h, then perform centrifugation and washing, and then freeze-drying for 12h to obtain a Staphylococcus aureus sample containing Co.

7. The production method according to claim 6, wherein The volume ratio of the ethanol and the sterile deionized water is 2:

1.

8. The production method according to claim 2, wherein In the step S2, the specific preparation process of solution A is as follows: mix the Staphylococcus aureus containing Co prepared in step S1, cobalt nitrate, zinc nitrate, manganese acetate and methanol, perform ultrasonic treatment for 0.5h, and then continue stirring for 1h to obtain solution A.

9. The production method according to claim 2, wherein In the step S4, the stirring reaction parameters are as follows: temperature is room temperature, and time is 5h.

10. The production method according to claim 2, wherein In the step S5, the specific steps of the pyrolysis reaction are as follows: pyrolysis in an argon atmosphere at a rate of 5℃ / min, first heat to 250℃ and keep for 60min, then heat to 950℃ and keep for 120min.

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