Boron-nitrogen co-doped porous carbon anode material, preparation method thereof and application of boron-nitrogen co-doped porous carbon anode material in microbial fuel cell
By forming a porous structure on the surface of the carbon felt and introducing boron and nitrogen co-doping, porous carbon anode materials with high specific surface area and high electrochemical activity were prepared, which solved the problems of hydrophobicity and low electron transfer efficiency of the anode materials of microbial fuel cell, and achieved the improvement of power density and stability.
Patent Information
- Application Number
- CN202510688549.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-27
- Publication Date
- 2025-08-29
AI Technical Summary
The anode materials of existing microbial fuel cells have problems such as high hydrophobicity, low specific surface area, slow electron transfer efficiency and insufficient electrochemical activity, which limit their power output and stability.
The porous structure was formed on the surface of the carbon felt by sodium citrate pyrolysis method, and boron and nitrogen co-doping was introduced into the carbon structure by the pyrolysis method of boric acid and melamine to prepare porous carbon anode materials with high specific surface area and high electrochemical activity, which promoted microbial adhesion and electron transfer.
It significantly improves the power density and cell stability of microbial fuel cells, enhances the biocompatibility and electrochemical activity of the anode material, and promotes the extracellular electron transfer process.
Smart Images
Figure CN120565702A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of microbial fuel cells, and in particular relates to a boron-nitrogen co-doped porous carbon anode material, a preparation method thereof, and an application thereof in microbial fuel cells. Background Art
[0002] With the growing demand for sustainable, renewable energy and cost-effective wastewater treatment technologies, microbial fuel cells (MFCs) have attracted widespread attention from both academia and industry as a technology that can simultaneously achieve environmentally friendly bioelectricity harvesting and wastewater bioremediation. In MFCs, exoelectronic bacteria act as biocatalysts, oxidizing organic matter (electron donors) through various extracellular electron transfer (EET) pathways and releasing electrons to an insoluble anode electrode, thereby driving current generation. This process not only converts chemical energy into electrical energy, but also eliminates greenhouse gas (e.g., CO2) emissions during operation, making MFCs a net-zero carbon bioenergy technology with broad application prospects in wastewater treatment, clean energy production, and environmental remediation.
[0003] However, the practical promotion of MFCs is still limited by their low power output and insufficient long-term operational stability. Specifically, existing technologies have the following bottlenecks: (1) The high hydrophobicity and low specific surface area of the anode surface lead to insufficient attachment density of electroactive microorganisms, making it difficult to form an efficient biofilm; (2) The kinetics of extracellular electron transfer (EET) at the microorganism-anode interface are slow, which seriously restricts the electron transfer efficiency; (3) Traditional carbon-based anode materials (such as carbon felt, carbon cloth, carbon brushes, etc.) have problems such as low surface electrochemical activity, insufficient specific capacitance, and a simple pore structure due to their physical and chemical property defects, which further limit the metabolic activity of microorganisms and the energy storage capacity of the electrode.
[0004] To address these issues, existing research focuses on optimizing carbon-based anode materials through two main strategies: first, constructing a hierarchical porous carbon framework to increase the specific surface area through a multi-level distribution of macropores, mesopores, and micropores to enhance microbial attachment and electron transfer efficiency; second, introducing heteroatom doping (such as nitrogen, boron, and sulfur) to improve conductivity and catalytic activity by manipulating the electronic structure of carbon materials. Related studies have shown that nitrogen-doped anodes can effectively increase the anode electron density, accelerate the extracellular electron transfer process in bioelectrochemical systems, and thus improve the power density of MFCs (Wang YX, Li WQ, He CS, et al. Active Ndopant states of electrodes regulate extracellular electron transfer of Shewanella oneidensis MR-1 for bioelectricity generation: Experimental and theoretical investigations [J]. Biosensors and Bioelectronics, 2020, 160: 112231). Although nitrogen doping has been widely demonstrated in improving the performance of MFC anodes, research in this field is relatively mature and there is limited room for further improvement. In contrast, the research on boron doping in the field of MFCs anode is still in its infancy and shows great development potential. Currently, the research on the catalytic and capacitive performance of boron doping is mostly concentrated in the fields of supercapacitors and electrocatalysis, while its application in MFCs is relatively rare, with only a few studies using it for MFCs cathodes. For example, when the boron-doped reduced graphene oxide (B-rGO) prepared by Lan et al. was used as the cathode of MFCs, it induced the generation of more active sites and enhanced electron transfer, with a power density of 411mW m -2(Lan R,Liu L,Feng H,et al.Boron-doped reduced graphene oxide as an efficient cathode in microbial fuel cells for biologicaltoxicity detection[J].Bioresource Technology,2024,403:130883). At present, the application of boron and nitrogen co-doping in MFCs anode is still in the preliminary exploratory stage, and related research is relatively scarce. The composite catalytic material of iron nanoparticles encapsulated within boron and nitrogen co-doped carbon nanoshell (B / NC@Fe) prepared by Zhou et al. (Zhou H,Wu S,Zhou Y,et al.Insights into the oxidation of organic contaminants by ironnanoparticles encapsulated within boron and nitrogen co-doped carbonnanoshell:Catalyzed Fenton-like reaction at natural pH[J].EnvironmentInternational,2019,128:77-88) is mainly used to degrade levofloxacin. Summary of the Invention
[0005] The present invention aims to provide a boron-nitrogen co-doped porous carbon anode material, its preparation method, and its application in microbial fuel cells. Using carbon felt as a carrier, the present invention in-situ generates a porous structure on the carbon fiber surface through the pyrolysis of sodium citrate, significantly increasing the material's specific surface area and the space for bacterial attachment. Boric acid and melamine are then introduced into the carbon structure through pyrolysis, significantly improving the carbon felt's surface activity and electrochemical performance. This results in a boron-nitrogen co-doped porous carbon anode material with a porous structure and high electrochemical activity, promoting the growth of electroactive microbial membranes at the anode and accelerating the efficiency of extracellular electron transfer.
[0006] The technical solutions for achieving the purpose of the present invention are as follows:
[0007] A method for preparing a boron-nitrogen co-doped porous carbon anode material comprises the following steps:
[0008] (1) Immerse the clean carbon felt material in a mixed solution of sodium citrate, boric acid, and melamine at 80-95°C. After complete immersion, take out the carbon felt material, dry it, and recrystallize it. The concentration of sodium citrate in the mixed solution is 0.1 g / mL.
[0009] (2) placing the recrystallized carbon felt material in a tubular furnace, introducing argon protection, and pyrolyzing it at 800-900°C, and cooling it to room temperature after the pyrolysis is completed;
[0010] (3) The pyrolyzed carbon felt was washed with dilute hydrochloric acid and hot water, and dried to obtain a boron-nitrogen co-doped porous carbon anode material (N / B-PCs@CF).
[0011] Preferably, in step (1) or (3), the drying temperature is 60-80° C., and the drying time is 3-5 h.
[0012] Preferably, in step (1), the mass ratio of boric acid to melamine is 1:3 to 3:1.
[0013] Preferably, in step (1), the mass ratio of sodium citrate, boric acid and melamine is 20:1:1.
[0014] Preferably, in step (2), the heating rate is 3-5° C. / min, the gas flow rate of argon is 10-15 sccm, and the holding time is 4-5 h.
[0015] Preferably, in step (3), the concentration of dilute hydrochloric acid is 1-3 mol / L, and the temperature of the hot water is 80-90°C.
[0016] The present invention provides a boron and nitrogen co-doped porous carbon anode material obtained by the above preparation method.
[0017] The present invention also provides application of the boron-nitrogen co-doped porous carbon anode material in a microbial fuel cell.
[0018] The present invention utilizes an impregnation-carbonization process to thermally decompose sodium citrate, forming an in-situ multi-layered porous structure with a high specific surface area on carbon felt. This provides more space for microbial attachment and aggregation. Nitrogen doping modifies the electronic structure of the carbon material, improving its conductivity and active sites, enhancing its conductivity and hydrophilicity, and thus increasing the affinity of the electrode surface for bacteria. Boron doping further optimizes the electron distribution at the anode, thereby inducing the generation of active sites and promoting the EET process. Its electron-deficient properties enhance the electrode's capacitive performance and improve the discharge stability of the microbial fuel cell.
[0019] Compared with the prior art, the present invention has the following advantages:
[0020] (1) The boron-nitrogen co-doped porous carbon anode material prepared by the present invention has a multi-level hierarchical pore structure with a high specific surface area and a highly electrochemically active surface. Boron-nitrogen co-doping optimizes the surface hydrophobicity of the material, improves the biocompatibility of the material, promotes the attachment of microorganisms and the occurrence of electrode surface reactions, and promotes the extracellular electron transfer process of MFCs, thereby improving the power density and battery stability.
[0021] (2) The boron-nitrogen co-doped porous carbon anode material of the present invention exhibits low resistance, high specific capacitance and large electrochemical active area, which is significantly superior to traditional carbon-based anode materials.
[0022] (3) The boron-nitrogen co-doped porous carbon anode material of the present invention is used as an anode material for microbial fuel cells, has good biocompatibility, is conducive to bacterial adhesion and enrichment, and promotes the formation of electroactive biofilms.
[0023] (4) The boron-nitrogen co-doped porous carbon anode material of the present invention is used as an anode material for microbial fuel cells. It has abundant electrochemically active centers, promotes the extracellular electron transfer process, significantly improves the power density of MFCs, and has capacitive properties, which can effectively improve the stability of the power output of microbial fuel cells.
[0024] (5) The preparation process of the boron-nitrogen co-doped porous carbon anode material of the present invention is simple, low-cost, environmentally friendly, suitable for large-scale production, and applicable to wastewater treatment and clean energy production. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 The cyclic voltammetry test diagrams of Example 1, Comparative Example 1 and Comparative Example 2 are shown;
[0026] Figure 2 The cyclic voltammetry test diagrams of Example 1, Comparative Example 3 and Comparative Example 4 are shown;
[0027] Figure 3 A comparison of the power generation performance of MFCs constructed with the anodes obtained in CF, Example 1, Example 2, Comparative Example 5, and Comparative Example 6; Figure 4 SEM images of the anodes prepared in CF (ab), Example 1 (cd), Example 2 (ef), Comparative Example 5 (gh) and Comparative Example 6 (ij) after stable operation in MFCs. DETAILED DESCRIPTION
[0028] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.
[0029] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.
[0030] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.
[0031] The present invention will be further described below in conjunction with the embodiments and accompanying drawings.
[0032] Example 1
[0033] A method for preparing a boron-nitrogen co-doped porous carbon anode material comprises the following steps:
[0034] (1) A 3 mm thick carbon felt was cut into 2 cm × 2 cm × 3 mm sizes and soaked in acetone overnight to remove surface impurities and grease. The cleaned carbon felt was then dried in an 80°C forced air drying oven for 3–5 h to obtain the original carbon felt material (CF).
[0035] (2) Weigh 2g of sodium citrate, 0.1g of boric acid, and 0.1g of melamine and dissolve them in 20mL of deionized water to prepare a mixed solution with a sodium citrate concentration of 0.1g / mL. Heat it to 95°C to completely dissolve it. Immerse the cut carbon felt completely in the mixed solution and stir it magnetically for 1h under heating conditions to ensure that the solution fully penetrates into the pores of the carbon felt. Subsequently, place the impregnated carbon felt in an oven at 80°C and dry it for 12h to complete the recrystallization process.
[0036] (3) The recrystallized carbon felt material was transferred to a tubular furnace and argon was introduced as a protective gas at a gas flow rate of 10 sccm. The furnace temperature was raised to 800°C at a heating rate of 5°C / min and maintained at this temperature for 5 h to ensure sufficient carbonization of the material. After pyrolysis was completed, the material was naturally cooled to room temperature.
[0037] (4) The pyrolyzed carbon felt material was removed and ultrasonically treated with a 2 mol / L dilute hydrochloric acid solution for 3 h. It was then washed with deionized water and then washed 5–7 times with 80°C hot water to remove surface impurities and undoped residues. Finally, the material was dried in an 80°C drying oven for 12 h to obtain a boron-nitrogen co-doped porous carbon anode material (N / B-PCs@CF).
[0038] Comparative Example 1
[0039] This comparative example is basically the same as Example 1, with the only difference being that the amount of sodium citrate used in step (1) is 0.05 g / mL. The porous structure on the carbon fiber surface of the obtained N / B-PCs@CF material fails to be effectively formed, and nitrogen atoms and boron atoms cannot be effectively doped subsequently, so that the specific surface area and electrochemical activity of the material cannot be significantly improved.
[0040] Comparative Example 2
[0041] This comparative example is basically the same as Example 1, with the only difference being that the amount of sodium citrate in step (1) is increased to 0.2 g / mL. Due to the large amount of sodium citrate used, the carbon fibers of the obtained N / B-PCs@CF material are blocked by the porous carbon layer and other reaction products, which in turn reduces the specific surface area of the material.
[0042] See also Figure 1In the cyclic voltammetry test diagrams of Example 1, Comparative Example 1 and Comparative Example 2 (scan rate of 30 mV / s), the electrochemical response areas of the boron-nitrogen co-doped porous carbon anode materials prepared with sodium citrate dosages of 0.05 g / mL and 0.2 g / mL are both smaller than the electrochemical response area of the boron-nitrogen co-doped porous carbon anode materials prepared with sodium citrate dosages of 0.2 g / mL, indicating that excessive or insufficient sodium citrate dosage is not conducive to the in-situ formation of a porous carbon layer on the carbon fiber surface.
[0043] Comparative Example 3
[0044] This comparative example is basically the same as Example 1, except that the pyrolysis temperature in step (3) is 700° C. When the pyrolysis temperature is low, sodium citrate cannot be fully pyrolyzed to form a porous carbon structure, and the specific surface area of the prepared material cannot be effectively improved.
[0045] Comparative Example 4
[0046] This comparative example is basically the same as Example 1, except that the pyrolysis temperature in step (3) is 1000° C. When the pyrolysis temperature is high, the porous carbon structure formed may collapse, resulting in decreased conductivity and structural stability of the material, and reduced electrochemical performance.
[0047] See also Figure 2 In the cyclic voltammetry test graphs of Example 1, Comparative Example 3 and Comparative Example 4, the scan rate was set to 5mV / s in order to accurately compare the performance differences of each electrode. When the pyrolysis temperature was 700°C and 1000°C, the electrochemical performance of the prepared N / B-PCs@CF anode material was not as ideal as that of Example 1. The figure shows that the cyclic voltammetry curve of Example 1 has a more obvious response current and a larger electrochemical response area, indicating that it has better electrochemical reversibility and higher specific capacity. The curves of Comparative Examples 3 and 4 show a lower response current and a smaller electrochemical response area, which further verifies the important influence of pyrolysis temperature on the performance of N / B-PCs@CF anode materials.
[0048] Example 2
[0049] This example is basically the same as Example 1, except that 0.15 g of boric acid and 0.15 g of melamine are added to 20 mL of the mixed solution.
[0050] Comparative Example 5
[0051] This comparative example is basically the same as Example 1, except that boric acid is not added to prepare a nitrogen co-doped porous carbon anode material (N-PCs@CF).
[0052] Comparative Example 6
[0053] This comparative example is basically the same as Example 1, except that melamine is not added to prepare a boron co-doped porous carbon anode material (B-PCs@CF).
[0054] Example 3
[0055] A double-chamber organic glass reactor was used, with the effective volume of the anode chamber and the cathode chamber being 120 mL, separated by a Nafion117 proton exchange membrane. Carbon felt material (CF), N / B-PCs@CF prepared in Examples 1 to 2, N-PCs@CF prepared in Comparative Example 5, and B-PCs@CF prepared in Comparative Example 6 were used as anodes, and carbon felt was used as cathode material. Electroactive Shewanella onesidensis MR-1 was selected as inoculum, and the MR-1 suspension was dispersed in 110 mL of anode solution until the OD 600 = 2.0. After inoculation into the MFC reactor, nitrogen was purged for 1 hour to create a sterile environment. The anolyte composition consisted of M9 + phosphate buffer solution (0.103 mol / L Na₂HPO₄·2H₂O, 0.071 mol / L KH₂PO₄, 8.56 mmol / L NaCl, 18.7 mmol / L NH₄Cl, 1 mmol / L MgSO₄·7H₂O, and 0.1 mmol / L CaCl₂·2H₂O), 18.3 mL TSB solution, and 20 mmol / L sodium lactate as a carbon source and electron donor. The catholyte consisted of 110 mL of a mixed solution of K₃[Fe(CN)₆] (50 mmol / L), KCl (50 mmol / L), Na₂HPO₄·2H₂O (40 mmol / L), and KH₂PO₄ (22 mmol / L). The assembled cell was connected in series with a 1000Ω resistor and monitored at a constant temperature of 30°C.
[0056] Depend on Figure 3 It can be seen that the initial discharge voltages of the N / B-PCs@CF anode MFCs of Example 1 and Example 2 (0.715V and 0.699V) are higher than those of the CF anode (0.491V), the N-PCs@CF anode of Comparative Example 5 (0.673V) and the B-PCs@CF anode of Comparative Example 6 (0.642V), indicating that N / B-PCs@CF reduces the electrocatalytic overpotential of the anode electroactive biofilm, and the single discharge time of the electrodes of Example 1 and Example 2 is significantly improved compared with the electrodes of CF, Comparative Example 5 and Comparative Example 6, indicating that the power output stability of the microbial fuel cell is improved. Figure 4SEM images of anodes prepared from CF (ab), Example 1 (cd), Example 2 (ef), Comparative Example 5 (gh), and Comparative Example 6 (ij) after stable operation in MFCs. The results show that only a small portion of the carbon fibers of CF were covered with microorganisms, while the N / B-PCs@CF anodes of Examples 1 and 2 were more covered with microorganisms. The single-doped electrodes of Comparative Examples 5 and 6 fell between the CF and the examples, indicating that the N / B-PCs@CF has a rougher surface and better biocompatibility, which facilitates microbial attachment.
[0057] In summary, the present invention achieves a significant improvement in anode performance through the preparation of boron and nitrogen co-doped porous carbon anode materials and their application in microbial fuel cells. The synergistic doping of boron and nitrogen atoms not only optimizes the electronic structure of the carbon matrix, but also enhances the conductivity and electrocatalytic activity of the electrode by forming BC and NC active sites. Experiments have shown that the material has the characteristics of high specific surface area, large electrochemically active surface area and good biocompatibility. Its multi-level porous structure provides abundant attachment sites for electricity-producing microorganisms and promotes the formation of dense biofilms. Applying N / B-PCs@CF to the anode of microbial fuel cells can enrich electroactive electricity-producing bacteria, promote the extracellular electron transfer process of microorganisms, and effectively solve the problems of low power density and poor discharge stability of MFCs.
[0058] The above are only preferred specific embodiments of the present invention. These specific embodiments are all different implementation methods based on the overall concept of the present invention. It should be clear that the scope of protection of the present invention is not limited to the above embodiments. Any process parameter adjustment (such as pyrolysis temperature gradient, doping ratio optimization) or structural improvement (such as introduction of other doping materials or nanomaterials) based on the boron and nitrogen co-doping mechanism falls within the scope of the claims of this patent. The technical solution of the present invention shall be based on the content defined in its claims and equivalent replacement solutions.
Claims
1. A method for preparing a boron-nitrogen co-doped porous carbon anode material, characterized in that: The steps include: (1) Immerse the clean carbon felt material in a mixed solution of sodium citrate, boric acid, and melamine at 80-95°C. After complete immersion, take out the carbon felt material, dry it, and recrystallize it. The concentration of sodium citrate in the mixed solution is 0.1 g / mL. (2) The recrystallized carbon felt material was placed in a tubular furnace, argon gas was introduced for protection, and pyrolysis was performed at 800-900 °C. After the pyrolysis was completed, the temperature was cooled to room temperature; (3) The carbon felt after pyrolysis is washed with dilute hydrochloric acid and hot water, and dried to obtain a boron-nitrogen co-doped porous carbon anode material.
2. The preparation method according to claim 1, characterized in that In step (1) or (3), the drying temperature is 60-80°C and the drying time is 3-5 hours.
3. The preparation method according to claim 1, characterized in that In step (1), the mass ratio of boric acid to melamine is 1:3 to 3:
1.
4. The preparation method according to claim 1, characterized in that In step (1), the mass ratio of sodium citrate, boric acid and melamine is 20:1:
1.
5. The preparation method according to claim 1, wherein In step (2), the heating rate is 3-5 °C / min, the gas flow rate of argon is 10-15 sccm, and the holding time is 4-5 h.
6. The preparation method according to claim 1, wherein In step (3), the concentration of dilute hydrochloric acid is 1-3 mol / L, and the temperature of hot water is 80-90 °C.
7. The boron-nitrogen co-doped porous carbon anode material obtained by the preparation method according to any one of claims 1 to 6.
8. Use of the boron-nitrogen co-doped porous carbon anode material according to claim 7 in a microbial fuel cell.