Three-dimensional self-supporting anode of microbial fuel cell as well as preparation method and application of three-dimensional self-supporting anode

Abstract

The invention relates to the technical field of microbial fuel cells, and particularly provides a three-dimensional self-supporting anode of a microbial fuel cell as well as a preparation method and application of the three-dimensional self-supporting anode. The method comprises the following steps: dissolving a carbon skeleton material and a carbon source in deionized water to obtain a mixed solution; preparing a binder aqueous solution; adding the mixed solution into the binder aqueous solution, uniformly stirring and mixing, and introducing into a mold to obtain a precursor; and sequentially carrying out standing refrigeration, standing freezing and freeze drying treatment, and then carrying out carbonization to obtain the three-dimensional self-supporting anode. The problems of poor hydrophilicity and insufficient active area of a traditional commercial electrode are successfully solved, and the defects that an existing modification method is complex in process and a biomass direct carbonization method is uncontrollable in structure are overcome; low-cost raw materials, an adjustable and simple process, an ideal porous conductive structure and excellent cell performance are organically combined, and a novel universal strategy with a wide application prospect is provided for preparation of a high-performance and low-cost microbial fuel cell anode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microbial fuel cells, in particular to a three-dimensional self-supporting anode of a microbial fuel cell and a preparation method and application thereof. BACKGROUND

[0002] The anode of a microbial fuel cell is a key interface for the attachment, growth and extracellular electron transfer of electrogenic microorganisms, and its performance directly determines the power generation efficiency and operational stability of the entire system. However, the currently widely used commercial carbon-based electrode materials (such as carbon felt, carbon cloth, etc.) have two major defects: first, the poor intrinsic hydrophilicity and limited electrochemical active area of the material lead to difficulties in initial microbial attachment and insufficient effective growth sites; second, the high electrode-microorganism interface electron transfer resistance and unstable biofilm formation caused by the above problems ultimately result in low battery output power and rapid performance degradation. These problems have seriously hindered the development of microbial fuel cells from the laboratory to practical applications. Therefore, developing a low-cost anode material with high biocompatibility, excellent electrochemical performance and good structural stability has become a key to promoting the development of this technology.

[0003] In view of the above bottlenecks, existing research mainly improves performance by surface modification of commercial carbon-based electrodes or replacement with new substrate materials, but both strategies have obvious limitations. On the one hand, surface modification based on commercial electrodes (such as loading carbon nanotubes, metal oxides or conductive polymers on carbon cloth) can partially improve performance, but the bonding force between the modified layer and the substrate often weakens with the extension of running time, and the complex modification process (such as high-temperature treatment, electrodeposition) greatly increases the preparation cost and complexity. For example, patent (CN115172769A) uses melamine sponge as a substrate to prepare a self-supporting anode through multi-step surface modification, which has a complex process and limited performance improvement (only 46%), indicating that this method has strong dependence on the inherent structure of the substrate material and insufficient controllability. On the other hand, directly using natural biomass as a precursor to prepare a new type of carbon electrode (such as patent CN118610502A using kudzu root to prepare an anode through freeze-drying and carbonization) can utilize the natural porous structure of the biomass to obtain good electrochemical performance, but the macroscopic size, microscopic morphology and composition of the electrode are limited by the shape and chemical composition of the original biomass, making it difficult to flexibly design and mass-produce according to actual application needs, and the scalability and universality are poor.

[0004] In summary, the prior art is difficult to balance between "low cost", "structural designability", "process simplicity" and "high performance". Specifically, the development of microbial fuel cell anode faces double challenges: first, a low-cost, easily accessible raw material system is needed, which not only can build a stable three-dimensional porous skeleton, but also can form an efficient conductive network inside the skeleton; second, a mild and controllable forming process is needed, which can not only avoid structural collapse, but also convert the above-mentioned raw material system into a self-supporting electrode with complete structure and through pores. Therefore, it is crucial to develop a universal preparation method based on general raw materials, simple process and free adjustment of electrode structure and performance for the practical application of microbial fuel cell technology. SUMMARY

[0005] The present application provides a three-dimensional self-supporting anode of microbial fuel cell and its preparation method and application, which aims to solve the above problems existing in the background art.

[0006] In order to achieve the above purpose, one aspect of the embodiment of the present application provides a preparation method of a three-dimensional self-supporting anode of microbial fuel cell, comprising the following steps:

[0007] S1: dissolving a carbon skeleton material and a carbon source in deionized water to obtain a mixed solution; dissolving a binder in deionized water to obtain a binder aqueous solution; adding the mixed solution into the binder aqueous solution, stirring and mixing uniformly, and introducing the mixed solution into a silica gel mold to obtain a precursor;

[0008] S2: sequentially placing the precursor in a refrigerator, freezing, and freeze-drying to obtain a precursor intermediate product;

[0009] S3: carbonizing the precursor intermediate product under the protection of an inert atmosphere to obtain the three-dimensional self-supporting anode.

[0010] Preferably, in the step S1, the carbon skeleton material is wheat flour; the carbon source is at least one of glucose, sucrose and maltose; and the binder is polyvinyl alcohol.

[0011] Preferably, in the step S1, the mass ratio of the binder to the carbon skeleton material is 0.08-0.15:1; the mass ratio of the carbon source to the carbon skeleton material is 0.4-0.6:1; the mass ratio of the deionized water to the binder is 10-15:1; and the mass ratio of the deionized water to the mixed solution is 1:1-3. Too low a proportion of the binder makes it impossible for the carbon skeleton material molecules to form effective cross-linking, and the prepared electrode has insufficient mechanical strength and is easy to break. Too high a proportion of the binder causes a large amount of voids and defects to be formed due to large-scale volatilization of the binder during pyrolysis, resulting in collapse of the electrode structure. Too low a proportion of the carbon source makes it impossible for large pores in the carbon skeleton to be effectively filled, and the conductivity of the prepared electrode is significantly reduced. Too high a proportion of the carbon source destroys the network structure of the carbon skeleton, and excessive filling of the pores causes the specific surface area of the electrode material to sharply decrease, which affects the electrode structure and electrochemical stability. Too low a proportion of the deionized water makes it impossible to form a moldable mixture. Too high a proportion of the deionized water affects the formation of the carbon skeleton network, resulting in discontinuous network, and the uniformity and conductivity of the electrode are significantly reduced.

[0012] Preferably, in the step S1, the binder dissolving process is performed at a water bath temperature of 70-100℃ for 1-2h; and the carbon skeleton material and the carbon source dissolving process are performed at a water bath temperature of 40-60℃ for 10-15min; and the stirring time is 2-4h.

[0013] Preferably, in the step S2, the standing refrigeration temperature is 2-6℃, and the standing refrigeration time is 8-12h; the standing freezing temperature is -20--10℃, and the standing freezing time is 8-12h; and the freeze-drying temperature is -45--20℃, and the freeze-drying time is 48-84h.

[0014] Preferably, in the step S3, the inert atmosphere is a nitrogen or argon protective atmosphere; and the carbonization process is divided into two stages: in the first stage, the temperature rising rate is 1-5℃ / min, the holding temperature is 100-150℃, and the holding time is 0.5-1h; and in the second stage, the temperature rising rate is 3-6℃ / min, the holding temperature is 850-1050℃, and the holding time is 2-3h. The first stage is a dehydration process for further removing residual water, and the second stage is a carbonization modification process.

[0015] An aspect of the embodiment of the present application further provides a three-dimensional self-supporting anode of a microbial fuel cell prepared by the preparation method.

[0016] Another aspect of the embodiment of the present application provides a microbial fuel cell, and the three-dimensional self-supporting anode of a microbial fuel cell prepared by the preparation method.

[0017] Preferably, the carbon cloth loaded with 10% Pt / C catalyst is an air cathode, an external resistance is connected to form a closed loop, the anolyte is simulated wastewater, and activated sludge is used as a source of electrogenic microorganisms.

[0018] More preferably, the single-chamber microbial fuel cell has the three-dimensional self-supporting anode, the carbon cloth air cathode loaded with 10% Pt / C catalyst, an external resistance of 1000 Ω is connected to form a closed loop, the anode is added with a mixed solution composed of simulated wastewater, yeast extract, trace vitamins and sodium acetate, and activated sludge is used as a source of electrogenic microorganisms.

[0019] Reaction principle: The present application uses wheat flour with excellent pore-forming properties as the carbon skeleton support body of the electrode, uses dissolved polyvinyl alcohol aqueous solution as the binder, the molecular chain of which forms a continuous connected polymer network in the whole system, and after being dissolved with the mixture of wheat flour and glucose, the precursor has good mechanical integrity during freeze-drying and carbonization, and the carbonization product of small molecule glucose can effectively fill the gaps between the carbonized particles of wheat flour, play a connecting role between the particles, reduce the contact resistance between the particles, thereby improving the electrical conductivity of the electrode material and reducing the charge transfer resistance of the electrode.

[0020] The above scheme of the present application has the following beneficial effects:

[0021] (1) The present application realizes low-cost and controllable simple preparation. The present application uses widely available and low-cost wheat flour and glucose as the main carbon source, and polyvinyl alcohol as the green binder, so that the raw material cost is much lower than that of commercial carbon felt and various nano-modified materials; by adjusting the ratio of wheat flour to glucose, the concentration and solid content of polyvinyl alcohol, the rheological properties of the precursor and the porosity, conductivity and mechanical strength of the final electrode can be accurately controlled, overcoming the defects of fixed form and difficulty in on-demand design of natural biomass precursors (such as whole block of kudzu root); the whole preparation process does not require complex equipment or harsh conditions, and can be completed through only three steps of co-dissolution, freeze-drying and carbonization, so that the process is simple, reproducible and easy to scale up.

[0022] (2) The present application constructs the physical basis of efficient electron transfer. The unique freeze-drying process effectively avoids the structural collapse caused by capillary force in traditional drying, and the pores formed by ice crystal sublimation are completely retained, and then fixed by carbonization, finally forming a three-dimensional network from micropores to macropores. This provides sufficient attachment sites, growth space and material transport channels for electricity-producing microorganisms; the carbonized wheat flour forms a porous skeleton main body, and the carbonized product of small molecule glucose uniformly fills the gap between the skeleton particles, playing the role of "conductive bridge". This design significantly reduces the contact resistance between particles, greatly reducing the charge transfer resistance of the overall electrode.

[0023] (3) The self-supporting electrode prepared by the present application shows overall performance superior to that of the commercial carbon felt electrode in the microbial fuel cell. The charge transfer resistance of the electrode is reduced by 85.1% compared with the commercial carbon felt, proving that the interface constructed greatly promotes the extracellular electron transfer process of microorganisms; the maximum output power density of the microbial fuel cell reaches 2.22 times that of the commercial carbon felt electrode, and the electricity-producing capacity realizes a qualitative leap; it is significantly superior to the commercial carbon felt electrode in many key evaluation indexes such as internal resistance, output voltage and long-term cycle stability, and shows excellent practical potential.

[0024] (4) The present application successfully solves the problems of poor hydrophilicity and insufficient active area of traditional commercial electrodes, and overcomes the shortcomings of complex process of existing modification methods and uncontrollable structure of biomass direct carbonization method; the low-cost raw materials, adjustable simple process, ideal porous conductive structure and excellent battery performance are organically combined, providing a widely applicable new strategy for the preparation of high-performance, low-cost microbial fuel cell anodes. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The scanning electron microscope image of the three-dimensional self-supporting anode prepared in Example 1 of the present application;

[0027] Figure 2 The cyclic voltammogram of the anode of Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, Comparative Example 3 of the present application;

[0028] Figure 3 The electrochemical impedance spectrogram of the anode of Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, Comparative Example 3 of the present application;

[0029] Figure 4 The output voltage curve diagram of the anode assembled microbial fuel cell of the present application example 1, example 2, example 3 and comparative example 1, comparative example 2, comparative example 3;

[0030] Figure 5 The power density curve diagram of the anode assembled microbial fuel cell of the present application example 1, example 2, example 3 and comparative example 1, comparative example 2, comparative example 3.

[0031] Figure 6 The polarization curve diagram of the anode assembled microbial fuel cell of the present application example 1, example 2, example 3 and comparative example 1, comparative example 2, comparative example 3. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and advantages of the present application more clear, the following will be described in detail in combination with the drawings and specific embodiments.

[0033] Unless otherwise defined, all the professional terms used in the following have the same meaning as that generally understood by the person skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application.

[0034] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by the existing method.

[0035] The present application aims at the existing problems and provides a three-dimensional self-supporting anode of microbial fuel cell and a preparation method and application thereof.

[0036] Example 1

[0037] A preparation method of a three-dimensional self-supporting anode is provided in the present embodiment, and the specific preparation steps are as follows:

[0038] Step one, 3g of polyvinyl alcohol is added to 30ml of deionized water, dissolved in water bath under 90℃ for 1h to obtain a clear and transparent adhesive aqueous solution. 25g of wheat flour and 10g of glucose are added to 50ml of deionized water, and the solution is stirred and dissolved in water bath under 60℃ for 10min to obtain a carbon skeleton mixed solution. The carbon skeleton mixed solution is added to the adhesive aqueous solution, and the two solutions are fully mixed and uniform by mechanical stirring for 2h. The obtained mixed solution is introduced into a silica gel mold, and then placed in a refrigerator at 4℃ for 12h, followed by freezing at-15℃ for 12h, and finally freeze-dried at-40℃ for 72h to obtain the dehydrated electrode material precursor.

[0039] Step two, the dehydrated electrode material precursor in step one is placed in an atmosphere protection furnace, first heated to 106℃ at a rate of 2℃ / min under nitrogen atmosphere, then heated to 900℃ at a rate of 5℃ / min for 2h, to obtain carbonized three-dimensional self-supporting anode electrode material. The carbonized electrode material is cut into the same size as the pretreated commercial carbon felt electrode, both are 3x3x0.5cm 3 size, and a three-dimensional self-supporting anode is obtained by connecting with titanium wire.

[0040] Step three, the electrode prepared in step two is used as anode, carbon cloth loaded with 10% Pt / C catalyst is used as air cathode, the anode and cathode are connected by copper wire and 1000Ω resistor to form a closed loop, 40ml of mixed solution composed of simulated wastewater, yeast extract, trace vitamins and sodium acetate is added to the anode, and 5g of activated sludge is used as source of producing microorganisms.

[0041] Example 2

[0042] Example 2 is different from example 1 only in that the glucose in step one is changed to sucrose, and the rest remains unchanged.

[0043] Example 3

[0044] Example 3 is different from example 1 only in that the carbonization temperature in step three is changed from 900℃ to 1000℃, and the rest remains unchanged.

[0045] Comparative example 1

[0046] In this comparative example, the pretreated commercial carbon felt electrode is used as anode, and the method for constructing single-chamber microbial fuel cell is the same as example 1.

[0047] The pretreatment step of carbon felt is as follows: the carbon felt electrode is cut into 3x3x0.5cm 3 size, and the cut carbon felt is soaked in 1mol / L hydrochloric acid solution and 1mol / L sodium hydroxide solution for 30min respectively, then soaked in deionized water until neutral, and dried in a blast drying oven at 60℃ for 12h to complete the pretreatment of carbon felt.

[0048] Comparative example 2

[0049] In this comparative example, the wheat flour in example 1 is changed to corn starch, and the rest remains unchanged.

[0050] Comparative example 3

[0051] In this comparative example, the glucose in example 1 is changed to citric acid, and the rest remains unchanged.

[0052] Electrochemical and microbial fuel cell electrical performance testing methods: Electrochemical testing employed a three-electrode system. The prepared anode served as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The electrolyte was a mixed solution of 0.2 mol / L sodium sulfate and 0.005 mol / L potassium hexacyanoferrate(III). Cyclic voltammetry curves and electrochemical impedance spectroscopy were measured for different anodes. Microbial fuel cells were assembled using different anodes and connected to a voltage data acquisition card. Voltage data was recorded every 10 minutes. The output voltage of the cell was recorded using the voltage data acquisition card, and the voltage-time curve was plotted. After several stable cycles, the anode solution was replaced. When the output voltage reached a stable value, the microbial fuel cell was opened for 12 hours, and the external resistance was changed from 9000 Ω to 50 Ω. The corresponding voltages were recorded, and the power density curve and polarization curve were calculated and plotted. The apparent internal resistance of the cell was approximated by fitting the polarization curve. The test results are shown in Table 1 below.

[0053] Table 1 shows the performance test results of the above embodiments and comparative examples.

[0054]

[0055] Figure 1 This is a scanning electron microscope image of the three-dimensional self-supporting anode material prepared in Example 1. Figure 1 It is evident that the material exhibits a clear porous network structure, which helps increase the specific surface area of ​​the electrode, providing favorable conditions for the attachment and growth of electrogenic microorganisms. Using wheat flour as the carbon skeleton allows for the formation of a three-dimensional network structure before pyrolysis, helping to maintain the structural integrity after carbonization. Furthermore, wheat flour contains over 11% protein, and during pyrolysis, elements such as nitrogen and sulfur are incorporated into the carbon skeleton, enhancing the surface electrochemical activity of the electrode material. In contrast, using starch as the carbon skeleton tends to form dense, low-porosity carbon blocks during pyrolysis, resulting in a smaller specific surface area, and the lack of nitrogen and sulfur doping leads to lower electrochemical performance of the electrode material.

[0056] Figure 2 Cyclic voltammetry curves for electrodes from different embodiments and comparative examples are shown. The results show that the peak oxidation current and area under the curve for all embodiment electrodes are significantly greater than those for the comparative example, indicating that the electrode prepared by this invention has a larger electrochemical active area, which is more conducive to promoting the mass transfer process between the anolyte and the electrode interface.

[0057] Figure 3 Electrochemical impedance spectroscopy (EIS) spectra of electrodes from different embodiments and comparative examples are shown. Figure 3It can be seen that the charge transfer resistance of Example 1, Example 2 and Example 3 is 4.77 Ω, 7.28 Ω and 7.8 Ω respectively, which is lower than that of Comparative Example 1 (32.01 Ω), Comparative Example 2 (15.98 Ω) and Comparative Example 3 (23.92 Ω). The lower the charge transfer resistance, the better the conductivity of the electrode and the lower the resistance of electron transfer.

[0058] Figure 4 The voltage-time curves of the microbial fuel cells assembled with the anodes of different examples and comparative examples are shown in Figure 4. It can be seen that the microbial fuel cells with the anodes of the examples not only have a higher output voltage than those with the anodes of the comparative examples, but also have a smaller voltage decay in the continuous multiple operation cycles, showing excellent cycle stability. Figure 4 It can be seen that the microbial fuel cells with the anodes of the examples not only have a higher output voltage than those with the anodes of the comparative examples, but also have a smaller voltage decay in the continuous multiple operation cycles, showing excellent cycle stability. Compared with Example 1, Comparative Example 3 not only has a smaller output voltage, but also has a slow output voltage drop stage, showing a significant tailing phenomenon. Although citric acid is often used as a carbon source, the acidic environment of the citric acid solution in the preparation process of the electrode material precursor destroys the mixed network structure formed by the wheat flour and polyvinyl alcohol, and there may be a problem of starch hydrolysis, which affects the uniformity of the precursor. During the carbonization process, a large amount of carboxyl groups of citric acid volatilize, which destroys the continuity of the conductive network of the electrode, the conductive network of the electrode is poorly constructed, and there is a defect in the filling and connecting effect of the carbon skeleton main body conductive network, resulting in a significant decrease in the extracellular electron transfer rate of the anode at a low carbon source concentration, and poor electrical performance of the electrode.

[0059] Figure 5 The power density curves of the microbial fuel cells assembled with the anodes of different examples and comparative examples are shown in Figure 5. The maximum power density of the anode of Example 1 is 883.6 mW / m², which is higher than that of Example 2 (692.3 mW / m²) and Example 3 (716.5 mW / m²), and is 2.22 times that of Comparative Example 1 (398.5 mW / m²). The maximum power density of the electrode of all examples is greater than that of the comparative examples, showing more excellent electrical performance. Compared with Comparative Example 2, the composition of the carbon skeleton main body of wheat flour of Example 1 not only contains starch, but also contains a small amount of protein. During the carbonization process of the electrode, nitrogen, sulfur and other elements contained therein will be doped into the carbon skeleton main body. The presence of these elements can improve the conductivity and hydrophilicity of the electrode, and is more conducive to the adhesion of the electrogenic microorganism on the surface of the anode and the formation of the biofilm, thereby improving the extracellular electron transfer efficiency and showing a greater power density.

[0060] Figure 6The polarization curves of the microbial fuel cells assembled with the anodes of different examples and comparative examples are shown. The results show that the apparent internal resistance of the microbial fuel cells assembled with the anodes of Example 1, Example 2 and Example 3 is 90.7 Ω, 105.7 Ω and 129.6 Ω respectively, which is lower than that of Comparative Example 1 (220.4 Ω), Comparative Example 2 (152.8 Ω) and Comparative Example 3 (177.2 Ω). The lower the internal resistance is, the smaller the polarization loss is, and the faster the extracellular electron transfer rate is.

[0061] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a three-dimensional self-supporting anode for a microbial fuel cell, characterized by, The preparation method comprises the following steps: S1: dissolving a carbon skeleton material and a carbon source in deionized water to obtain a mixed solution; dissolving a binder in deionized water to obtain a binder aqueous solution; adding the mixed solution into the binder aqueous solution, stirring and mixing, and introducing the mixed solution into a mold to obtain a precursor; S2: sequentially performing refrigeration standing, freezing standing and freeze-drying treatment on the precursor to obtain a precursor intermediate product; S3: carbonizing the precursor intermediate product under protection of an inert atmosphere to obtain the three-dimensional self-supporting anode.

2. The method of claim 1, wherein the method further comprises the step of: In the step S1, the carbon skeleton material is wheat flour; the carbon source is at least one of glucose, sucrose and maltose; and the binder is polyvinyl alcohol. ​ 3. The method of claim 1, wherein the method further comprises the step of: 3-1) drying the self-supporting anode at a temperature of 30°C to 100°C for 1 to 24 hours. In the step S1, the mass ratio of the binder to the carbon skeleton material is 0.08-0.15:1; the mass ratio of the carbon source to the carbon skeleton material is 0.4-0.6:1; the mass ratio of the deionized water to the binder is 10-15:1; and the mass ratio of the deionized water to the mixed solution is 1:1-3.

4. The method for preparing a three-dimensional self-supporting anode for a microbial fuel cell according to claim 1, characterized in that, In the step S1, the binder dissolving process is performed at a water bath temperature of 70-100 DEG C for 1-2 hours; and the carbon skeleton material and the carbon source dissolving process are performed at a water bath temperature of 40-60 DEG C for 10-15 minutes; and the stirring time is 2-4 hours.

5. The method for preparing a three-dimensional self-supporting anode for a microbial fuel cell according to claim 1, characterized in that, In the step S2, the refrigeration standing temperature is 2-6 DEG C, and the refrigeration standing time is 8-12 hours; the freezing standing temperature is -20 DEG C to -10 DEG C, and the freezing standing time is 8-12 hours; and the freeze-drying temperature is -45 DEG C to -20 DEG C, and the freeze-drying time is 48-84 hours.

6. The method for preparing a three-dimensional self-supporting anode for a microbial fuel cell according to claim 1, characterized in that, In the step S3, the inert atmosphere is a nitrogen or argon protective atmosphere; the carbonization process is divided into two stages: the first stage has a temperature rising rate of 1-5 DEG C / min, a holding temperature of 100-150 DEG C and a holding time of 0.5-1 hour; and the second stage has a temperature rising rate of 3-6 DEG C / min, a holding temperature of 850-1050 DEG C and a holding time of 2-3 hours.

7. A three-dimensional self-supporting anode of a microbial fuel cell, which is prepared by the preparation method according to any one of claims 1-6.

8. A microbial fuel cell characterized by, A microbial fuel cell comprising the three-dimensional self-supporting anode prepared by the preparation method according to any one of claims 1-6.

9. The microbial fuel cell of claim 8, wherein, The carbon cloth loaded with 10% Pt / C catalyst is used as an air cathode, an external resistance is connected to form a closed loop, and active sludge is used as a source of electricity-producing microorganisms.

Images