Iron-based multi-metal sulfide composite carbon anode material and preparation method thereof

Abstract

The invention belongs to the technical field of new energy materials and bioelectrochemistry, and particularly relates to an iron-based multi-metal sulfide composite carbon anode material and a preparation method of the iron-based multi-metal sulfide composite carbon anode material. The preparation method is simple in process flow, convenient to operate, easy for large-scale production, wide in raw material source, low in cost and environment-friendly, and can be used for preparing the three-dimensional porous carbon matrix which is formed by foaming and carbonizing polyvinylpyrrolidone and is provided with interconnected carbon nanosheets. Through reasonable composition design and structural regulation, and optimization of metal ratio and vulcanization conditions, accurate regulation of material performance can be realized, electrochemical performance and biocompatibility are significantly improved, electricity generation performance and operation stability of a microbial fuel cell are improved, and good industrial application prospects are achieved.

Description

Technical fields:

[0001] This invention belongs to the field of new energy materials and bioelectrochemistry technology, specifically relating to a high-performance iron-based multi-metal sulfide composite carbon anode material and its preparation method, for use in microbial fuel cells. Background technology:

[0002] Microbial fuel cells (MFCs) are a novel environmentally friendly device that can directly convert the chemical energy in organic waste into electrical energy, and they have broad application prospects in wastewater treatment, biosensing, and renewable energy production. However, the practical application of MFCs is greatly limited by factors such as low power output, slow start-up speed, unstable operation, and high manufacturing cost.

[0003] As a key component for microbial attachment and electron transfer, the performance of the anode material directly affects the power generation efficiency of MFCs. An ideal anode material should possess excellent conductivity, a large specific surface area, good biocompatibility, stable chemical properties, and a suitable three-dimensional pore structure. While commonly used carbon-based materials (such as carbon felt, carbon cloth, and carbon paper) exhibit good conductivity, they suffer from poor biocompatibility, limited specific surface area, and difficulties in microbial attachment, severely impacting the enrichment of electroactive microorganisms and the efficiency of extracellular electron transfer.

[0004] In recent years, transition metal sulfides have been widely used in MFC anode modification due to their good conductivity, excellent electrocatalytic activity, and biocompatibility. Among the many transition metal sulfides, iron-based sulfides (such as FeS and FeS2) have attracted particular attention due to their abundant resources and low cost. However, single metal sulfides suffer from limited active sites, poor stability, and low electron transfer efficiency. Polymetallic sulfides can significantly improve electrocatalytic performance through the synergistic effect between different metal elements; however, they suffer from complex preparation processes, high costs, and a lack of systematic research on metal ratio optimization and performance evaluation systems. For example, Chinese Patent 202510666446.6 discloses a method for preparing MAX phase-derived polymetallic sulfides, including the following steps: (1) Weighing MAX phase, K2S, metal chloride etchant, NaCl and KCl according to a certain molar ratio; (2) Pouring the solid powder weighed in (1) into a mortar and grinding it to make the powder evenly dispersed; (3) Transferring the powder in (2) to a corundum boat, heating it to a certain temperature and holding it at that temperature under an inert atmosphere in a tube furnace, then cooling it to 300°C and then naturally cooling it to room temperature; (4) Washing the solid powder obtained in (3) and collecting it by vacuum filtration, and then drying it under vacuum to obtain the polymetallic sulfide material; Step (1) The molar ratio in step (3) includes 1:(2-8):3:3:2, the MAX phase includes one or more of Nb2AlC, Ti3AlC2, V2AlC, TiNbAlC, TiVAlC, Mo2TiAlC2, Mo3AlC2, TiVNbMoAlC3 and TiVCrMoAlC3, and the metal chloride etchant includes one or more of CuCl2, FeCl2, CoCl2, SnCl2, ZnCl2 and NiCl2; the reaction temperature in step (3) is 600-800℃, the holding time is 2-8h, and the inert atmosphere is any one or a mixture of helium, neon, argon and nitrogen.Chinese Patent 202510031785.7 discloses a method for preparing metal cation-doped polymetallic sulfide nanospheres, comprising the following steps: mixing a dispersion of a metal-organic framework material, a molybdate, and a sulfur-containing compound, and performing a hydrothermal or solvothermal reaction to obtain metal cation-doped polymetallic sulfide nanospheres; the metal cations in the metal-organic framework material include cobalt ions and nickel ions, or cobalt ions and manganese ions, or cobalt ions, nickel ions, and manganese ions; the organic ligands in the metal-organic framework material include 2-methylimidazole and / or terephthalic acid; the sulfur-containing compound includes one or more of thiourea, thioacetamide, ammonium sulfide, and sodium thiosulfate; the temperature of the hydrothermal or solvothermal reaction is 180–220°C, the holding time is 6–24 h, and the molybdate is sodium molybdate; after the hydrothermal or solvothermal reaction, the method further comprises: cooling the product obtained from the hydrothermal or solvothermal reaction to room temperature, separating the solid and liquid, and sequentially washing and drying the obtained solid; the drying temperature is 60–120°C; and the drying time is 6–12 h.

[0005] Furthermore, existing technologies lack systematic research on the synergistic doping of iron with multiple metals such as cobalt, nickel, molybdenum, and tungsten, followed by further sulfidation, particularly in its application as anode materials for microbial fuel cells. Therefore, developing a low-cost, high-performance iron-based multi-metal sulfide composite carbon anode material and its preparation method is of great significance for promoting the practical application of microbial fuel cells. Summary of the Invention:

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and to design an iron-based multi-metal sulfide composite carbon anode material and its preparation method, which can significantly improve the start-up speed and power output of MFC.

[0007] To achieve the above objectives, the iron-based multi-metal sulfide composite carbon anode material of the present invention includes a base metal, an auxiliary metal, and a three-dimensional porous carbon matrix. Multi-metal sulfide nanoparticles formed by doping the auxiliary metal into the base metal and then sulfiding are uniformly loaded into a three-dimensional porous carbon matrix formed by foaming and carbonizing the carbon source polyvinylpyrrolidone (PVP), and are applied to the anode of a microbial fuel cell.

[0008] The molar ratio of the base metal to the auxiliary metal is 1:0.1-1.0, preferably 1:0.3-0.7;

[0009] The content of basic and auxiliary metal elements is 10-70 wt%, the content of sulfur is 5-30 wt%, the content of carbon is 20-80 wt%, and the remainder is oxygen and other unavoidable impurities.

[0010] The base metal involved in this invention is iron;

[0011] The auxiliary metal is at least one of cobalt, nickel, molybdenum, and tungsten;

[0012] Multi-metal sulfides include at least two of Fe7S8, FeS2, FeS, Co9S8, NiS, MoS2, and WS2, and the metal sulfides form a close heterojunction structure. Through the synergistic effect of geometric, electronic and stabilization effects, the electrocatalytic activity is significantly improved. The heterojunction interface formed between different metal sulfides is conducive to charge separation and transfer.

[0013] The three-dimensional porous carbon matrix has a three-dimensional porous structure with interconnected carbon nanosheets. Multi-metal sulfide nanoparticles are uniformly embedded on the surface of carbon nanosheets or coated in carbon layers, forming a typical core-shell structure. The three-dimensional porous structure can provide a large number of microbial attachment sites, promote the enrichment and colonization of electroactive microorganisms, and the interconnected pore structure is conducive to the transport of substrates and metabolites, improving biofilm activity. The interconnected carbon nanosheet structure forms a continuous conductive network, which promotes rapid electron transfer.

[0014] The specific process of preparing the iron-based multi-metal sulfide composite carbon anode material involved in this invention includes the following steps:

[0015] First, carbon source polyvinylpyrrolidone, base metal and auxiliary metal are dissolved in water to form a precursor solution, which is then dried and ground to obtain precursor powder.

[0016] The base metal is an iron source, selected from at least one of ferric nitrate, ferric chloride, ferric sulfate, and ferric acetylacetone.

[0017] The auxiliary metal source is selected from at least one of cobalt nitrate, cobalt chloride, cobalt sulfate, nickel nitrate, nickel chloride, nickel sulfate, ammonium molybdate, phosphomolybdic acid, sodium molybdate / sodium tungstate, and ammonium paratungstate;

[0018] The mass ratio of the carbon source polyvinylpyrrolidone to (base metal and auxiliary metal) is 1:(1-3);

[0019] Then, the precursor powder was pyrolyzed under an inert atmosphere to obtain a metal carbide / metal composite three-dimensional porous carbon material.

[0020] The pyrolysis treatment temperature is 600-800℃, the holding time is 1-3 hours, and the heating rate is 2-10℃ / min.

[0021] Finally, the metal carbide / metal composite three-dimensional porous carbon material and sulfur powder were mixed at a mass ratio of 1:0.2-3.0 and subjected to sulfidation treatment to obtain iron-based multi-metal sulfide composite carbon anode material.

[0022] The vulcanization treatment temperature is 500-600℃, the holding time is 1-2 hours, and the heating rate is 1-5℃ / min.

[0023] The iron-based multi-metal sulfide composite carbon anode material prepared in this invention is mixed with a binder, coated onto a carbon matrix, and dried. As an anode for microbial fuel cells, it can significantly improve the start-up speed and operational stability of MFCs, reduce charge transfer resistance, increase exchange current density, promote the enrichment of specific electroactive microorganisms (such as Desulfuromonas), and optimize the microbial community structure.

[0024] Compared with existing technologies, this invention provides a high-performance, low-cost multi-metal sulfide composite carbon anode material and its preparation method. Using polyvinylpyrrolidone as the carbon source and iron and at least one of cobalt, nickel, molybdenum, or tungsten as metal sources, a composite material with a three-dimensional porous structure and multi-component sulfide heterojunction is prepared through a foaming-carbonization-sulfurization process. As an anode for microbial fuel cells, it possesses a three-dimensional porous structure, high specific surface area, excellent conductivity, electrocatalytic activity, and biocompatibility. It can significantly improve the start-up speed, power output, and density of MFCs, reduce charge transfer resistance, and promote the enrichment of electroactive microorganisms. The rational ratio of iron to other metals in the multi-metal sulfide composite carbon anode material optimizes the band structure and electronic state density. Its preparation method is simple, low-cost, and environmentally friendly, suitable for large-scale production, and has broad application prospects in microbial fuel cells, biosensors, and wastewater treatment. Attached image description:

[0025] Figure 1 The XRD pattern of the Fe7S8 / MoS2@PC composite carbon anode material prepared in Example 2 of this invention.

[0026] Figure 2 SEM image of the Fe7S8 / MoS2@PC composite carbon anode material prepared in Example 2 of this invention.

[0027] Figure 3 This is a TEM image of the Fe7S8 / MoS2@PC composite carbon anode material prepared in Example 2 of the present invention.

[0028] Figure 4 SEM image of the bioanode microbial membrane of the Fe7S8 / MoS2@PC composite carbon anode material prepared in Example 2 of the present invention. Detailed implementation method:

[0029] The invention will be further described below through implementation examples and in conjunction with the accompanying drawings.

[0030] Example 1:

[0031] The specific process of preparing the iron-based multi-metal sulfide composite carbon anode material involved in this embodiment includes the following steps:

[0032] ①Preparation of precursor powder

[0033] First, the carbon source polyvinylpyrrolidone (PVP) is dissolved in deionized water to prepare a solution with a concentration of 0.5-5 wt%. Then, a basic metal source and an auxiliary metal source are added in a molar ratio of 1:0.1-1.0 (preferably 1:0.3-0.7). The mixture is stirred at room temperature for 0.5-3 hours to ensure thorough mixing and obtain the precursor solution.

[0034] Then, the precursor solution is dried at 40-80℃ for 6-48 hours to obtain a solid precursor.

[0035] Finally, the solid precursor is ground into precursor powder with a particle size of 50-200 mesh;

[0036] The basic metal source is selected from at least one of ferric nitrate, ferric chloride, ferric sulfate, and ferric acetylacetone, preferably ferric nitrate nonahydrate (Fe(NO3)3·9H2O);

[0037] The auxiliary metal sources include cobalt, nickel, molybdenum and tungsten. The cobalt source is selected from cobalt nitrate, cobalt chloride and cobalt sulfate. The nickel source is selected from nickel nitrate, nickel chloride and nickel sulfate. The molybdenum source is selected from ammonium molybdate, phosphomolybdic acid and sodium molybdate. The tungsten source is selected from sodium tungstate and ammonium paratungstate.

[0038] The mass ratio of the carbon source polyvinylpyrrolidone (PVP) to the total metal salts in the base metal source and auxiliary metal source is 1:1-3, preferably 1:1.5-2.5;

[0039] ②Pyrolysis

[0040] The precursor powder was placed in a tube furnace for carbonization treatment. Under the protection of an inert atmosphere, the temperature was raised to 600-800℃ at a heating rate of 2-10℃ / min, held for 1-3 hours, and then naturally cooled to room temperature to obtain a metal carbide / metal composite three-dimensional porous carbon material.

[0041] ③ Sulfidation

[0042] Metal carbide / metal composite three-dimensional porous carbon material is uniformly mixed with sulfur powder at a mass ratio of 1:0.2-3 and subjected to a sulfidation reaction. Under inert atmosphere protection, the temperature is raised to 500-600℃ at a heating rate of 1-5℃ / min, held for 1-2 hours, and then cooled to obtain iron-based multi-metal sulfide composite carbon anode material.

[0043] The sulfidation mass ratio (S: metal carbide / metal composite three-dimensional porous carbon material) is 0.5-1.0, preferably 0.8-1.0.

[0044] The iron-based multi-metal sulfide composite carbon anode material prepared in this embodiment is mixed with a binder solution at a mass ratio of 1:10-100 and then coated or dripped onto a carbon matrix. After drying at room temperature for 12-48 hours, it can be used as an anode for microbial fuel cells.

[0045] The adhesive is selected from at least one of Nafion solution, polytetrafluoroethylene emulsion, and polyvinyl alcohol solution, preferably Nafion solution;

[0046] The carbon matrix is ​​selected from at least one of carbon felt, carbon cloth, carbon paper, and graphite felt, with carbon felt being preferred.

[0047] Example 2:

[0048] This embodiment relates to a method for preparing Fe / Mo binary metal sulfide composite carbon anode materials, and the specific process is as follows:

[0049] First, weigh 1g of carbon source PVP (K30) and dissolve it in 30mL of deionized water. Stir magnetically for 30 minutes until completely dissolved. Then add 1.5g of Fe(NO3)3·9H2O and 0.2g of ammonium molybdate (H2O). 24 Mo7N6O 24 ·4H2O), continue stirring for 1 hour to mix thoroughly, dry at 60℃ for 48 hours to obtain a yellow-brown solid, grind and pass through a 100-mesh sieve to obtain precursor powder;

[0050] Then, the precursor powder was placed in a tube furnace for carbonization treatment. Under argon protection, the temperature was raised to 700°C at a rate of 5°C / min, held for 1 hour, and then naturally cooled to obtain Fe2MoC@PC composite three-dimensional porous carbon material.

[0051] Finally, 0.1g of Fe2MoC@PC composite three-dimensional porous carbon material was thoroughly mixed with 0.1g of sulfur powder and subjected to sulfidation treatment. Under argon protection, the temperature was raised to 550℃ at a rate of 2℃ / min, held for 1 hour, and then cooled to obtain Fe7S8 / MoS2@PC composite carbon anode material.

[0052] The process for preparing microbial fuel cells using Fe7S8 / MoS2@PC composite carbon anode material is as follows: 30 mg of Fe7S8 / MoS2@PC composite carbon anode material is mixed evenly with 1 mL of Nafion solution (5 wt%), ultrasonically dispersed for 30 minutes, and the resulting slurry is drop-coated onto a 2 cm × 2 cm carbon felt and dried at room temperature for 24 hours to obtain Fe7S8 / MoS2@PC-CF modified anode.

[0053] Example 3:

[0054] This embodiment relates to a method for preparing Fe / Ni binary metal sulfide composite carbon anode materials, and the specific process is as follows:

[0055] Weigh 1g of carbon source PVP and dissolve it in 30mL of deionized water. Stir magnetically for 30 minutes, then add 0.9g of Fe(NO3)3·9H2O and 0.6g of Ni(NO3)2·6H2O. Continue stirring for 1 hour. The subsequent drying, grinding, and carbonization processes are the same as in Example 2, to obtain Fe. x Ni y @PC composite three-dimensional porous carbon material;

[0056] 0.1g Fe x Ni y @PC composite three-dimensional porous carbon material was thoroughly mixed with 0.1g of sulfur powder and subjected to sulfidation treatment. Under argon protection, the temperature was raised to 550℃ at a rate of 2℃ / min, held for 1 hour, and then cooled to obtain Fe7S8 / NiS@PC composite carbon anode material.

[0057] The process for preparing microbial fuel cells using Fe7S8 / NiS@PC composite carbon anode material is as follows: 30 mg of Fe7S8 / NiS@PC composite carbon anode material is mixed evenly with 1 mL of Nafion solution, and then drip-coated onto a carbon felt. The mixture is dried at room temperature for 24 hours to obtain Fe7S8 / NiS@PC-CF modified anode.

[0058] Example 4

[0059] This embodiment relates to a method for preparing Fe / Co binary metal sulfide composite carbon anode materials, and the specific process is as follows:

[0060] First, weigh 1g of carbon source PVP and dissolve it in 30mL of deionized water. Stir magnetically for 30 minutes, then add 1g of Fe(NO3)3·9H2O and 0.5g of Co(NO3)2·6H2O. Continue stirring for 1 hour. The subsequent drying and grinding process is the same as in Example 2.

[0061] Then, the obtained precursor powder was heated to 700℃ at a rate of 5℃ / min under argon protection and held for 1 hour to obtain Fe / Co metal carbide / metal composite three-dimensional porous carbon material.

[0062] Finally, 0.1g of Fe / Co metal carbide / metal composite three-dimensional porous carbon material was thoroughly mixed with 0.08g of sulfur powder, and the mixture was heated to 550℃ at a rate of 2℃ / min under argon protection and held at that temperature for 1 hour to obtain Fe / Co iron-based binary metal sulfide composite carbon anode material.

[0063] The process for preparing microbial fuel cells using Fe / Co iron-based binary metal sulfide composite carbon anode material is as follows: 30 mg of Fe / Co iron-based binary metal sulfide composite carbon anode material is mixed evenly with 1 mL of Nafion solution, and then drip-coated onto a carbon felt. The mixture is dried at room temperature for 24 hours to obtain Fe / Co iron-based binary metal sulfide-CF modified anode.

[0064] Example 5

[0065] This embodiment relates to a method for preparing Fe / Ni / Mo ternary metal sulfide composite carbon anode materials, and the specific process is as follows:

[0066] First, weigh 1g of carbon source PVP and dissolve it in 30mL of deionized water. Stir magnetically for 30 minutes, then add 0.8g of Fe(NO3)3·9H2O, 0.4g of Ni(NO3)2·6H2O and 0.15g of ammonium molybdate. Continue stirring for 1 hour. The subsequent drying and grinding process is the same as in Example 2.

[0067] Then, the obtained precursor powder was heated to 700℃ at a rate of 5℃ / min under argon protection and held for 1 hour to obtain Fe / Ni / Mo metal carbide / metal composite three-dimensional porous carbon material.

[0068] Finally, 0.1g of Fe / Ni / Mo metal carbide / metal composite three-dimensional porous carbon material was thoroughly mixed with 0.1g of sulfur powder, and the mixture was heated to 550℃ at a rate of 2℃ / min under argon protection and held for 1 hour to obtain Fe / Ni / Mo iron-based ternary metal sulfide composite carbon anode material.

[0069] The process for preparing microbial fuel cells using Fe / Ni / Mo iron-based ternary metal sulfide composite carbon anode material is as follows: 30 mg of Fe / Ni / Mo iron-based ternary metal sulfide composite carbon anode material is mixed evenly with 1 mL of Nafion solution, and then drip-coated onto a carbon felt. After drying at room temperature for 24 hours, Fe / Ni / Mo iron-based ternary metal sulfide-CF modified anode is obtained.

Claims

1. A type of iron-based multi-metal sulfide composite carbon anode material, characterized in that, Includes base metals, auxiliary metals, and a three-dimensional porous carbon matrix; The base metal is iron; The auxiliary metal is at least one of cobalt, nickel, molybdenum, and tungsten.

2. The iron-based multi-metal sulfide composite carbon anode material according to claim 1, characterized in that, The molar ratio of the base metal to the auxiliary metal is 1:0.1-1.

3. The method for preparing an iron-based multi-metal sulfide composite carbon anode material according to claim 1 or 2, characterized in that, Multi-metal sulfide nanoparticles, formed by sulfidation of auxiliary metals into base metals, are uniformly loaded into a three-dimensional porous carbon matrix formed by foaming and carbonization of polyvinylpyrrolidone (PVP) as a carbon source.

4. The method for preparing an iron-based multi-metal sulfide composite carbon anode material according to claim 3, characterized in that, The content of basic and auxiliary metal elements is 10-70 wt%, the content of sulfur is 5-30 wt%, and the content of carbon is 20-80 wt%.

5. The method for preparing an iron-based multi-metal sulfide composite carbon anode material according to claim 3, characterized in that, The specific process includes the following steps: First, carbon source polyvinylpyrrolidone, base metal and auxiliary metal are dissolved in water to form a precursor solution, which is then dried and ground to obtain precursor powder. Then, the precursor powder was pyrolyzed under an inert atmosphere to obtain a metal carbide / metal composite three-dimensional porous carbon material. Finally, the metal carbide / metal composite three-dimensional porous carbon material was mixed with sulfur powder and subjected to sulfidation treatment to obtain iron-based multi-metal sulfide composite carbon anode material.

6. The method for preparing an iron-based multi-metal sulfide composite carbon anode material according to claim 5, characterized in that, The mass ratio of the carbon source polyvinylpyrrolidone to the base metal and auxiliary metal is 1:1-3.

7. The method for preparing an iron-based multi-metal sulfide composite carbon anode material according to claim 5, characterized in that, The pyrolysis treatment temperature is 600-800℃, the holding time is 1-3 hours, and the heating rate is 2-10℃ / min.

8. The method for preparing an iron-based multi-metal sulfide composite carbon anode material according to claim 5, characterized in that, The mass ratio of metal carbide / metal composite three-dimensional porous carbon material to sulfur powder is 1:0.2-3; The vulcanization temperature is 500-600℃, the holding time is 1-2 hours, and the heating rate is 1-5℃ / min.

9. The method for preparing an iron-based multi-metal sulfide composite carbon anode material according to claim 3, characterized in that, The prepared iron-based multi-metal sulfide composite carbon anode material was applied to the anode of a microbial fuel cell.

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