System for producing acid based on mxene material combined with bioelectrochemical enhanced carbon dioxide reduction, method for producing acid and application

Abstract

The application discloses a system for producing acid based on carbon dioxide electro-reduction by combining MXene material and bio-electrochemical enhancement, and has the characteristics that the system comprises an anode chamber, a cathode chamber, a proton exchange membrane and a constant potential instrument; the anode chamber and the cathode chamber are connected in isolation through the proton exchange membrane, and the constant potential instrument is connected with the lead wire penetrating through the anode lead wire port arranged on the anode chamber, the lead wire penetrating through the cathode lead wire port arranged on the cathode chamber and the reference electrode arranged in the cathode chamber; and the MXene material is added into the cathode chamber. The application also discloses a method for producing acid by microorganism carbon dioxide electro-reduction by using the system, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of bioelectrochemical technology, and relates to a system, method and application of acid production based on MXene material combined with bioelectrochemical enhancement of carbon dioxide electroreduction. Background Technology

[0002] With the acceleration of global industrialization, global carbon dioxide emissions are increasing year by year. Currently, the main methods for carbon dioxide fixation and conversion include photocatalytic conversion, electrocatalytic reduction, and bioconversion. However, these technologies suffer from problems such as stringent conditions, low efficiency, and poor selectivity, and require further development and research.

[0003] Bioelectrocatalysis is a technology based on electrochemical systems, introducing suitable microorganisms as catalysts to catalyze the reduction of carbon dioxide. It can convert carbon dioxide into high-value-added carbon compounds at ambient temperature and pressure. Driven by an external power source, and using electroactive microorganisms as biocatalysts, it achieves carbon dioxide fixation and reduction under mild conditions. Compared to other carbon dioxide fixation and conversion technologies, this technology has advantages such as mild reaction conditions and product diversity.

[0004] While this technology boasts the advantages and feasibility mentioned above, it also presents challenges such as long start-up times and unstable microbial growth. Significant room for further research and development is still needed in areas such as the exploration of electron transfer principles and reactor engineering.

[0005] MXene, a novel two-dimensional material, has garnered widespread attention in the scientific community since its discovery in 2011 due to its unique structure and excellent performance. MXene is etched from its precursor, the MAX phase. Its high conductivity, rich surface chemistry, and microscopic multilevel structure have demonstrated significant application potential in various fields, including electrochemical energy storage (lithium-ion batteries, supercapacitors), electromagnetic interference shielding, sensing, electrocatalysis, biomedicine, and environmental remediation. Furthermore, its excellent electrochemical performance and biocompatibility make it a promising candidate for application in microbial electrocatalysis.

[0006] Chinese invention patent application "A Highly Catalytically Active Co-NC / MXene Catalyst and Its Preparation Method and Application" (Publication No. CN116470072A, Publication Date 2023.07.21) proposes a method for preparing a highly catalytically active Co-NC / MXene catalyst and applies it to microbial fuel cells. By utilizing the high conductivity, stability, and biocompatibility of MXene to replace conventional noble metal Pt / C catalysts, the ORR activity and reaction kinetic rate of the cathode reaction in microbial fuel cells are successfully improved, thereby increasing the output power of the MFC. This demonstrates the great potential of this catalyst in microbial fuel cells.

[0007] Chinese invention patent "A Magnetic Mxene Microbial Carrier Material and Its Preparation Method" (Authorization Announcement No. CN114455690B, Authorization Announcement Date 2023.1.31) proposes a magnetic Mxene microbial carrier material and applies it to the treatment of oilfield wastewater. This material can adsorb suspended solids in wastewater, effectively increasing microbial activity, greatly enhancing the ability of microorganisms to treat wastewater, and effectively reducing the COD of the wastewater.

[0008] Chinese invention patent application "A Catalytic Ozone Oxidation Water Treatment Method for Regulating the Structural Properties of MXene with Carbon Nitride" (Publication No. CN120644227A, Publication Date 2025.9.16) discloses a catalytic ozone oxidation water treatment method for regulating the structural properties of MXene with carbon nitride. MXene is used in a catalytic ozone oxidation system for the deep treatment of pharmaceutical wastewater. Under conditions such as ozone concentration of 5-20 mg / L, catalyst dosage of 50-200 mg / L, and pH of 4.0-10.6, the ibuprofen removal rate can be increased from 28.0% to 90.1%, achieving efficient degradation of trace organic matter.

[0009] In summary, MXene materials have been explored in fields such as microbial fuel cells and wastewater treatment. However, no technology has yet applied them to the field of microbial electrocatalytic reduction of carbon dioxide. This invention introduces MXene materials into a microbial electrocatalytic system, utilizing its high conductivity, biocompatibility, and other properties to enhance the carbon dioxide reduction of the microbial electrocatalytic system. In this invention, MXene not only promotes efficient electron transfer to drive the electrocatalytic reaction, but its surface properties also provide a better attachment and growth environment for microorganisms, thereby enhancing the acid production efficiency. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a system based on MXene material combined with bioelectrochemical enhancement for carbon dioxide electroreduction to acid production, which addresses the deficiencies of current microbial catalytic electroreduction of carbon dioxide. The invention proposes a method for adding MXene material to the reactor. Utilizing MXene's excellent biocompatibility, large specific surface area, and extremely high conductivity, this provides microorganisms with more growth and attachment sites, promoting electron transfer efficiency within the reactor. This, in turn, shortens reactor start-up time and improves the reactor's carbon dioxide to acid production efficiency.

[0011] The system of this invention comprises an anode chamber and a cathode chamber connected by ball-grooved clamps. An anode electrode and a cathode electrode are respectively disposed within the anode chamber and cathode chamber. A proton exchange membrane is placed between the anode chamber and cathode chamber, and a potentiostat is positioned outside the chambers. In the anode chamber, an oxidation reaction occurs, releasing electrons and protons. Protons in the electrolyte are transported from the anode chamber to the cathode chamber through the proton exchange membrane. Electrons are transferred to the cathode electrode through the anode electrode and the potentiostat. Electroactive microorganisms on the surface of the cathode electrode in the cathode chamber utilize the transferred electrons and protons to reduce dissolved carbon dioxide in the cathode electrolyte.

[0012] The specific technical solution for achieving the objective of this invention is as follows:

[0013] A bioelectrochemical carbon dioxide electroreduction acid production system includes an anode chamber, a cathode chamber, a proton exchange membrane, and a potentiostat.

[0014] The anode chamber and the cathode chamber are isolated and connected by a proton exchange membrane. An external potentiostat is connected to the wires passing through the anode wire port on the anode chamber, the cathode wire port on the cathode chamber, and the reference electrode in the cathode chamber. MXene material is added inside the cathode chamber.

[0015] The anode chamber consists of an anode compartment and an anode electrode. The anode compartment is bottle-shaped, with an opening on one side for connection to the cathode compartment. An anode wire inlet is located at the top, and a liquid inlet / outlet pipe extends into the bottom of the compartment. The anode electrode is a ruthenium-iridium-titanium mesh spiral electrode, composed of a ruthenium-iridium-plated titanium rod welded with four 90° fan-shaped ruthenium-iridium-plated titanium meshes. Each ruthenium-iridium-titanium mesh is wrapped with carbon felt. A wire is connected to the electrode, extending from the anode wire inlet. A three-way switch is located at the top of the liquid inlet / outlet pipe to maintain an anaerobic environment within the anode chamber.

[0016] The cathode chamber consists of a cathode chamber and a cathode electrode. The cathode chamber is bottle-shaped, with an opening on one side for connection to the anode chamber. A liquid inlet / outlet pipe and a gas aeration pipe extend into the bottom of the bottle from the top. A gas inlet / outlet pipe and a cathode wire inlet are also located at the top. The cathode electrode is a ruthenium-iridium-titanium mesh spiral electrode, composed of a ruthenium-iridium-plated titanium rod welded with four 90° sector-shaped ruthenium-iridium-plated titanium meshes. Each ruthenium-iridium-titanium mesh is wrapped with carbon felt. A wire is connected to the electrode, extending from the cathode wire inlet. An aluminum foil gas sampling bag is connected to the gas inlet / outlet pipe. A three-way switch is located at the upper end of both the gas inlet / outlet pipe and the liquid inlet / outlet pipe to maintain an anaerobic environment within the cathode chamber.

[0017] The gas aeration tube is a sand-core glass aeration tube, and the reference electrode is a silver chloride electrode.

[0018] In one specific embodiment, the gas inlet / outlet pipe is also externally connected to an aluminum foil gas sampling bag to collect the gas generated in the cathode chamber, and is connected to a gas aeration pipe via a gas vacuum pump; the gas vacuum pump can periodically and quantitatively circulate the gas in the aluminum foil gas sampling bag back into the system.

[0019] The potentiostat is located outside the reactor and is electrically connected to the anode electrode of the anode chamber, the cathode electrode of the cathode chamber, and the reference electrode via wires.

[0020] This invention prepares MXene (TiNbC) by etching the MAX phase (TiNbAlC) with hydrofluoric acid. After dispersing MXene in the electrolyte, MXene is added to the cathode chamber of the reactor, which disperses it in the cathode electrode and the chamber to improve the electron transfer efficiency and acid production efficiency in the reactor.

[0021] The present invention also provides a method for microbial catalytic electroreduction of carbon dioxide to produce acid using the above system, comprising:

[0022] Step 1: Add electrolyte to the cathode chamber and anode chamber, and add anaerobic activated sludge containing electroactive microorganisms to the cathode chamber;

[0023] Step 2: Adjust the voltage of the potentiostat so that the voltage between the anode electrode and the reference electrode is 0.6~1.0 V;

[0024] Step 3: Add carbon dioxide to the aluminum foil gas collection bag as the sole carbon source for the electroactive microorganisms to reduce and produce acid.

[0025] This invention provides an MXene material, wherein the material refers to TiNbC powder, and its preparation method mainly includes the following steps:

[0026] Step 1: Disperse TiNbAlC powder in hydrofluoric acid solution and sonicate for 30 minutes to obtain TiNbAlC suspension;

[0027] Step 2: Place the TiNbAlC suspension in a 50℃ constant temperature water bath and stir continuously to etch and obtain a TiNbCMXene suspension;

[0028] Step 3: Wash and centrifuge the TiNbC MXene suspension alternately with deionized water and anhydrous ethanol. Dry the resulting precipitate in a vacuum oven at 60°C for 12 hours to obtain TiNbC MXene powder material.

[0029] The present invention also provides the application of the above system or method in microbial catalytic carbon dioxide reduction, etc.

[0030] The beneficial effects of the present invention include: the present invention sets ruthenium-iridium-titanium mesh spiral electrodes in the anode chamber and the cathode chamber. The electrode shape increases the contact area between the electrode and microorganisms, so that more activated sludge can be enriched on the electrode surface, promoting the growth of microorganisms. The electrodes and reference electrodes in the two chambers are respectively connected to a potentiostat. The arrangement of the two electrodes constitutes a bioelectrocatalytic reduction of carbon dioxide reaction device.

[0031] Compared with existing carbon dioxide fixation and reduction devices, this invention introduces a novel material, MXene, based on microbial electrocatalysis. By adding MXene to the cathode chamber, its high conductivity, high specific surface area, and high biocompatibility not only promote the enrichment of electroactive microorganisms in the cathode chamber and improve electron transfer efficiency, thereby increasing the acid production efficiency of the reactor, but also provide a new approach to solving problems such as long start-up cycles and unstable microbial growth in microbial electrolysis cells.

[0032] By adding 0.06 g of MXene material, the acetic acid production efficiency of the reactor was increased from 4.131 mg / L to 1518.5 mg / L, the coulombic efficiency of acetic acid reached 78.30%, and the electron transport activity on the biofilm surface increased from 66.32 ± 7.21 mg / cm². 2 / h increased to 224.49±20.20 mg / cm 2 / h, the protein content in the biofilm EPS increased from 22.19 mg / L to 62.04 mg / L. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of the present invention.

[0035] Figure 2 This is a schematic diagram of the electrode structure of the present invention. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the specific embodiments and accompanying drawings. Except for the contents specifically mentioned below, the processes, conditions, and experimental methods for implementing the present invention are all common knowledge and general knowledge in the art, and the present invention does not have any particular limitations.

[0037] This invention provides a system for enhancing carbon dioxide electroreduction to produce acid based on MXene material combined with bioelectrochemistry. The key feature of this invention is the addition of MXene material to a basic microbial electrolysis cell, leveraging the biocompatibility and high conductivity of MXene to create a system for enhancing carbon dioxide electroreduction to produce acid through MXene combined with bioelectrochemistry. The experimental setup includes a cathode chamber 2, an anode chamber 1, a proton exchange membrane 3, and a potentiostat 4. This invention enhances the electron transfer efficiency of the system by adding MXene material 14 to the cathode chamber 2, while an oxidation reaction occurs in the anode chamber 1 to release electrons (ep). - ) and proton (H + H in the electrolyte + Transmembrane transport from anode chamber 1 to cathode chamber 2, e - The bio-cathode surface is transferred via an external circuit, and then the electroactive microorganisms at the cathode utilize H... + With e - Reduce dissolved carbon dioxide (CO3) in the cathode electrolyte 2- HCO3 - When MXene material is added to the electrolyte in cathode chamber 2, it acts as an electron carrier between the electrode and microorganisms, and between microorganisms and carbon dioxide, promoting the growth of cathode biofilm and improving the electron transfer efficiency of the system.

[0038] In the figure, 1-anode chamber, 2-cathode chamber, 3-proton exchange membrane, 4-potentiostat, 5-cathode lead port, 6-cathode liquid inlet / outlet pipe, 7-gas aeration pipe, 8-gas inlet / outlet pipe, 9-reference electrode, 10-cathode electrode, 11-anode liquid inlet / outlet pipe, 12-anode lead port, 13-anode electrode, 14-MXene material, 15-gas sampling bag, 16-gas circulation pump, 17-ruthenium-iridium-titanium rod, 18-ruthenium-iridium-titanium mesh.

[0039] See Figure 1 The present invention includes an anode chamber 1, a cathode chamber 2, a proton exchange membrane 3, and a potentiostat 4.

[0040] The anode chamber 1 and the cathode chamber 2 are isolated and connected by a proton exchange membrane 3. An external potentiostat 4 is connected to the wires passing through the anode wire port 12 on the anode chamber 1, the cathode wire port 5 on the cathode chamber 2, and the reference electrode 9 in the cathode chamber. MXene material 14 is added inside the cathode chamber 2.

[0041] See Figure 1 The anode chamber 1 is a bottle-shaped component with an opening on one side. Inside, there is a ruthenium-iridium titanium mesh spiral anode electrode 13, an anode wire port 12, and an anode liquid inlet / outlet pipe 11. The anode electrode 13 is composed of a ruthenium-iridium plated titanium rod welded 17 to four 90° fan-shaped ruthenium-iridium plated titanium meshes 18. The ruthenium-iridium titanium meshes 18 are wrapped with carbon felt. A wire is connected to the anode electrode 13, and the wire port leads out from the anode wire port 12 and connects to the potentiostat 4.

[0042] The cathode chamber 2 is a bottle-shaped component with an opening on one side. Inside, a ruthenium-iridium-titanium mesh spiral cathode electrode 10 is installed. Above, a cathode liquid inlet / outlet pipe 6 and a gas aeration pipe 7 extend into the bottom of the bottle. A gas inlet / outlet pipe 8 is also located at the top, and a reference electrode 9 is located on the side. The cathode electrode 10 consists of a ruthenium-iridium-plated titanium rod welded 17 to four 90° fan-shaped ruthenium-iridium-plated titanium meshes 18. Carbon felt is wrapped around the ruthenium-iridium-titanium meshes 18. A wire is connected to the cathode electrode 10, extending from the cathode wire outlet 5 to a potentiostat 4. MXene material 14 is dispersed inside the cathode chamber 2 and on the cathode electrode 10. The gas aeration pipe 7 is a frosted glass aeration pipe, and the reference electrode 9 is a silver chloride electrode.

[0043] The gas inlet / outlet pipe 8 is also connected to an aluminum foil gas sampling bag to collect the gas generated in the cathode chamber 2, and is connected to the gas aeration pipe 7 through a gas vacuum pump 16; the gas vacuum pump 16 can circulate the gas in the gas sampling bag 15 at regular intervals and in a quantitative manner so that the gas can re-enter the system.

[0044] The proton exchange membrane 3 is located between the two chambers. It isolates the anode chamber 1 and the cathode chamber 2, selectively allowing protons to pass from the anode chamber 1 to the cathode chamber 2, while preventing the free exchange of other substances. It completes the circuit for the entire electrochemical reaction while maintaining an independent environment for the two chambers.

[0045] The potentiostat 4 is located outside the reactor and is electrically connected to the anode electrode 13 of the anode chamber 1, the cathode electrode 10 of the cathode chamber 2, and the reference electrode 9 via wires.

[0046] The anode chamber 1 is used for oxidation to release electrons and protons. Protons enter the cathode chamber 2 from the anode chamber 1 through the proton exchange membrane 3, and electrons are transferred to the cathode electrode 10 through the anode electrode 13 and the potentiostat 4, where carbon dioxide reduction occurs under a specific voltage.

[0047] After being dispersed in the electrolyte, the MXene material 14 is added to the cathode chamber 2 through the liquid inlet / outlet pipe 6.

[0048] Example 1:

[0049] See Figure 1 The present invention describes the catalytic reduction of carbon dioxide to produce high-value-added carbon compounds. The specific steps are as follows:

[0050] The first step is to connect the anode chamber 1, the cathode chamber 2, and the proton exchange membrane 3 together using ball mill clamps, and then perform leak testing to ensure good airtightness inside the reactor in order to maintain the stability of the anaerobic environment.

[0051] The second step involves adding anaerobic activated sludge and electrolyte containing electroactive microorganisms into the cathode chamber 2 through the cathode liquid inlet / outlet pipe 6; and adding electrolyte into the anode chamber 1 through the anode liquid inlet / outlet pipe 11.

[0052] The third step is to introduce carbon dioxide into the cathode chamber 2 through the gas aeration pipe 7 at regular intervals and in a quantitative manner to maintain the anaerobic environment in the chamber; connect an aluminum foil gas sampling bag to the gas inlet and outlet pipe 8 of the cathode chamber 2 to quantitatively supplement carbon dioxide into it as a carbon source for the reactor. At the same time, the aluminum foil gas sampling bag also serves as a gas collection bag, and the change in gas volume in the bag is recorded daily.

[0053] Fourth step: Adjust the potentiostat 4 to make the voltage between the anode electrode 13 and the reference electrode 9 0.8V;

[0054] Fifth step: Add 0.06g of MXene material dispersed in electrolyte into the cathode chamber 2 through the cathode liquid inlet / outlet pipe 6;

[0055] Step 6: Set up four groups of reactions with 0g, 0.02g, 0.04g, and 0.06g of MXene material 14 respectively, and observe the effect of different amounts of MXene material 14 on carbon dioxide bioelectrocatalysis;

[0056] Step 7: Using gas chromatography (GC), the components of the generated gas inside are detected through the aluminum foil gas sampling bag connected to the gas inlet / outlet tube 8; the electrolyte in the cathode chamber 2 is collected through the cathode liquid inlet / outlet tube 6, filtered through a 0.45 μm microporous membrane to remove residue, and then stored at low temperature for the determination of indicators such as VFA, SCOD, PN, PS, and ETSA.

[0057] Step 8: The enrichment level of functional microorganisms on the electrodes and the biofilm status were observed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Microbial community structure and diversity were analyzed using 16S rRNA gene sequences.

[0058] As can be seen from the examples, under the microbial electrochemical environment, the production of volatile acids increases with the increase of the dosage of MXene material 14, and the highest acetic acid production in the 0.06g group can reach 1518.5 mg / L.

[0059] Observations using scanning electron microscopy and laser confocal scanning microscopy showed that the growth of microorganisms on the carbon felt of the composite electrode increased with the increase of the amount of MXene material added.

[0060] Analysis of the microorganisms on the electrode revealed that the addition of MXene material can enrich the relevant acid-producing and methanogenic bacteria on the electrode surface, thereby improving the efficiency and selectivity of the reaction system for product formation.

[0061] This invention ultimately creates suitable reaction conditions for electroactive microorganisms to reduce carbon dioxide and generate high-value-added carbon compounds through a microbial electrochemical system and the addition of MXene material. MXene material, with its high conductivity, high specific surface area, and high biocompatibility, provides an attachment surface for electroactive microorganisms, promoting efficient interspecies electron transfer. The surface electron transfer activity increased from 66.32 ± 7.21 mg / cm². 2 / h increased to 224.49±20.20 mg / cm 2 / h, which improves the efficiency of electron transfer and carbon dioxide conversion between microorganisms, and increases the coulombic efficiency of acetic acid to 78.30%.

[0062] The electrolyte used in this example consisted of the following components: MgCl₂∙6H₂O 0.5 g / L, CaCl₂∙2H₂O 0.1875 g / L, NH₄Cl 0.625 g / L, K₂HPO₄ 1.09 g / L, KH₂PO₄ 0.85 g / L, NaHCO₃ 1.25 g / L, cysteine ​​0.25 g / L, yeast 0.5 g / L, and trace element solution 1 mL / L.

[0063] The trace element solution composition is as follows: FeCl2∙4H2O 5 g / L, CoCl2∙6H2O 0.425 g / L, ZnCl2 0.175 g / L, H3BO3 0.15 g / L, MnCl2∙2H2O 1.25 g / L, NiCl2∙6H2O 0.1 g / L, CuCl2∙2H2O 0.068 g / L, NaMoO4∙2H2O 0.063 g / L.

[0064] Compared with existing technologies, this system has the following significant advantages:

[0065] 1. Fast start-up speed: Compared to traditional microbial electrocatalytic reduction of carbon dioxide, this invention, through the introduction of MXene material, promotes electron transfer and microbial attachment, accelerating the enrichment of the cathode functional microbial community and the formation of biofilm, thereby shortening the system's start-up cycle. Compared to the longer start-up cycle of traditional microbial electrocatalytic systems, by adding MXene material, an acetic acid production efficiency of 1518.5 mg / L can be achieved within three days after the microbial growth stabilizes.

[0066] 2. High carbon dioxide utilization efficiency: Through the gas circulation design of the aluminum foil gas bag, the gas is repeatedly introduced into the cathode chamber, improving the gas utilization rate of the system.

[0067] 3. The acid production efficiency is significantly improved. With the addition of MXene material, the acid production efficiency can be increased from 9.76 mg / L without MXene material to a maximum of 1518.5 mg / L; the coulombic efficiency can reach up to 78.30%.

[0068] The scope of protection of this invention is not limited to the above embodiments. Any variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of this invention are included in this invention and are protected by the appended claims.

Claims

1. A system based on MXene material combined with bioelectrochemical enhancement for carbon dioxide electroreduction to produce acid, characterized in that, The system includes an anode chamber (1), a cathode chamber (2), a proton exchange membrane (3), and a potentiostat (4). The anode chamber (1) and the cathode chamber (2) are isolated and connected by a proton exchange membrane (3). An external potentiostat (4) is connected to the wires that pass through the anode wire port (12) set on the anode chamber (1), the cathode wire port (5) set on the cathode chamber (2), and the reference electrode (9) set in the cathode chamber (2). MXene material (14) is added inside the cathode chamber (2).

2. The system as described in claim 1, characterized in that, An anode liquid inlet / outlet pipe (11) is also provided on the anode chamber (1), which connects the interior of the anode chamber (1) to the outside. A three-way switch is provided at the upper end of the anode liquid inlet / outlet pipe (11). The lower end of the wire passing through the anode wire port (12) is connected to the anode electrode (13). The anode electrode (13) is a ruthenium-iridium-titanium electrode.

3. The system as described in claim 1, characterized in that, The cathode chamber (2) is also provided with a cathode liquid inlet / outlet pipe (6), a gas aeration pipe (7), and a gas inlet / outlet pipe (8); the cathode liquid inlet / outlet pipe (6), the gas aeration pipe (7), and the gas inlet / outlet pipe (8) are respectively connected to the inside and outside of the cathode chamber (2); a three-way switch is provided at the upper end of the cathode liquid inlet / outlet pipe (6), the gas aeration pipe (7), and the gas inlet / outlet pipe (8); the lower end of the wire passing through the cathode wire port (5) is connected to the cathode electrode (10); the cathode electrode (10) is a ruthenium-iridium-titanium electrode; the gas inlet / outlet pipe (8) is connected to an aluminum foil gas sampling bag to collect the gas generated in the cathode chamber (2), and is connected to the gas aeration pipe (7) through a gas vacuum pump (16).

4. The system as described in claim 2, characterized in that, The anode electrode (13) uses a ruthenium-iridium titanium electrode with a mesh spiral structure, including a central ruthenium-iridium titanium rod and four ruthenium-iridium titanium meshes fixed in a circular shape on the outside of the titanium rod, each of which is wrapped with carbon felt.

5. The system as described in claim 3, characterized in that, The gas aeration pipe (7) is a sand core glass aeration pipe, and the reference electrode (9) is a silver chloride electrode; the ruthenium-iridium titanium electrode used in the cathode electrode (10) has a mesh spiral structure, including a central ruthenium-iridium titanium rod and multiple ruthenium-iridium titanium meshes fixed in a circular shape on the outside of the titanium rod, each of the ruthenium-iridium titanium meshes is wrapped with carbon felt.

6. The system as described in claim 3, characterized in that, The MXene material (14) is TiNbC formed by etching MAX phase TiNbAlC with hydrofluoric acid; after the MXene material (14) is added to the cathode chamber (2), it is dispersed and adsorbed on the cathode electrode (10) or in the electrolyte in the cathode chamber (2).

7. The system as described in claim 3, characterized in that, The gas in the aluminum foil gas sampling bag is circulated back into the system at regular intervals and in quantitative quantities by a gas vacuum pump (16).

8. A method for producing acid by microbial catalytic electroreduction of carbon dioxide, characterized in that, The method applies the system as described in any one of claims 1-7, comprising: Step 1: Add electrolyte to the cathode chamber and anode chamber, and add anaerobic activated sludge containing electroactive microorganisms to the cathode chamber; Step 2: Adjust the voltage of the potentiostat so that the voltage between the anode electrode and the reference electrode is 0.6~1.0 V; Step 3: Add carbon dioxide to the aluminum foil gas collection bag as the sole carbon source for the electroactive microorganisms to reduce and produce acid.

9. A method for preparing MXene material, characterized in that, The preparation method includes the following steps: Step 1: Disperse TiNbAlC powder in hydrofluoric acid solution and sonicate for 30 minutes to obtain TiNbAlC suspension; Step 2: Place the TiNbAlC suspension in a 50℃ constant temperature water bath and stir continuously to etch and obtain a TiNbC MXene suspension; Step 3: Wash and centrifuge the TiNbC MXene suspension alternately with deionized water and anhydrous ethanol. Dry the resulting precipitate in a vacuum oven at 60°C for 12 hours to obtain TiNbC MXene powder material.

10. The application of the system as described in any one of claims 1-7 or the method as described in claim 8 in microbial catalytic carbon dioxide reduction.

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