Electrochemical biological coupling system based on carbon dioxide and seawater as raw materials and application

Abstract

The present application relates to the field of microbial technology, in particular to an electrochemical biological coupling system based on carbon dioxide and seawater as raw materials and application. The electrochemical biological coupling system comprises at least one series connection electrocatalytic system for electrochemically reducing CO2 into carbon source products; at least one bioreactor for further producing target biological products by fermentation using the carbon source and seawater; the microorganism inoculated in the bioreactor is Vibrio natriophilus (Vibrio natriophilus) Vibrio natriegens ); the product outlet of each series connection electrocatalytic system is communicated with the inlet of the bioreactor. The present application ingeniously integrates two independent but complementary systems of electrocatalysis and biological fermentation together to form an efficient and sustainable biological production platform, and the whole process uses CO2 and seawater as raw materials, which has significant environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, specifically to an electrochemical-biological coupling system and its application based on carbon dioxide and seawater as raw materials. Background Technology

[0002] Utilizing renewable energy to electrochemically convert CO2 into high-value-added chemicals is currently a mainstream research direction for addressing CO2 emissions. Although metal catalysts have shown promise in producing C1 and C2 liquid products (formic acid, formaldehyde, methanol, acetic acid, ethanol, etc.) from CO2, the efficient conversion of CO2 into longer-chain molecules remains a significant challenge due to the complexity of the reaction pathways. Hybrid bio-inorganic systems, by combining microbial cell factories with electrocatalytic CO2 reduction, offer a potential solution for the sustainable synthesis of valuable long-chain chemicals. However, scaling up hybrid bio-electrochemical systems faces significant challenges: 1) Maintaining the selectivity of the target product and long-term operational stability during high-intensity CO2 electroreduction remains a technical challenge. 2) Microbial strains typically have limited ability to effectively utilize electrocatalytic products (such as acetate and ethanol).

[0003] Most microorganisms require a clean culture environment with optimized pH and osmotic pressure, which conflicts with the alkaline electrolytes (1.0–5.0 M NaOH / KOH) typically used to improve CO2RR efficiency and C2 compound formation. Neutralizing these high concentrations of alkaline electrolytes with acid results in products with high concentrations of sodium or potassium ions. These electrolytes lead to low concentrations of microbial products, requiring expensive purification processes or hindering direct microbial utilization, thus compromising sustainability.

[0004] 3) The rapid generation of reduction products during electrolysis usually exceeds the metabolic capacity of microorganisms, leading to substrate accumulation or inhibition.

[0005] Currently, various electrochemical CO2 reduction systems coupled with bioreactors exist. In the electrochemical CO2 reduction phase, other materials catalyze the generation of different C1 or C2 products, such as formic acid, methanol, or ethanol; other materials may also generate acetic acid. Furthermore, other microorganisms, such as E. coli and yeast, can utilize the products of electrochemical reduction. For example: CN202411485191.5 A system for preparing acrylic acid using carbon dioxide via electro-biological coupling, wherein electrocatalysis is performed under the action of ZnO-ZrO2 catalyst to obtain methanol from CO2, and then methanol and Pichia pastoris are used for fermentation, but a nutrient carbon source needs to be added during the fermentation process.

[0006] CN202311333496.X describes an electrochemical-biofermentation coupling system for the preparation of bioplastics. It uses an electrochemical method to produce formic acid as a carbon source to supply Rawlston bacteria for growth and bioplastic production. However, this system has low biomass and cannot use seawater for fermentation.

[0007] These electrochemical-biological coupling systems all use fresh water for fermentation. In future scale-up production, they will use a large amount of fresh water resources or use electrochemical products as a supplementary carbon source to add to conventional culture media. In contrast, this fermentation system is a fermentation system that uses all inorganic chemical raw materials for production. Summary of the Invention

[0008] The purpose of this invention is to provide an electrochemical-biological coupling system and its application based on carbon dioxide and seawater, which solves the problems existing in the prior art.

[0009] The present invention achieves the above objectives through the following technical solutions: First, the present invention provides an electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials, comprising: At least one tandem electrocatalytic system for the electrochemical reduction of CO2 to carbon source products; The series electrocatalytic system includes two MEA electrolyzers connected in series. Each MEA electrolyzer includes a cathode electrode and an anode electrode. Both cathode electrodes are loaded with catalysts. According to the processing sequence, the cathode electrode of the first MEA electrolyzer is loaded with an OD-Ag catalyst, and the cathode electrode of the second MEA electrolyzer is loaded with a Cu3Pd catalyst. At least one bioreactor for further producing the target biological product by fermentation using the carbon source and seawater; The microorganisms inoculated in the bioreactor are sodium-dependent Vibrio (NaHCO3). Vibrio natriegens ); The product outlet of each tandem electrocatalytic system is connected to the inlet of the bioreactor.

[0010] As a further improvement of the present invention, the MEA electrolyzer also includes an ion exchange membrane, a gas diffusion layer, and a current collector plate.

[0011] As a further improvement of the present invention, the preparation process of the cathode electrode is as follows: (1) Carbon black and polytetrafluoroethylene nanoparticles (PTFE) were added to ethanol to prepare PTFE ink. After ultrasonic treatment, the PTFE ink was sprayed onto the gas diffusion electrode (GDE) at 90°C and dried to obtain an enhanced GDE. (2) At 120°C, the cathode ink is air-sprayed onto the enhanced GDE and dried to obtain the cathode electrode.

[0012] As a further improvement of the present invention, the cathode ink includes Cu3Pd ink and OD-Ag ink.

[0013] As a further improvement of the present invention, the cathode ink is prepared by mixing Cu3Pd or nano silver powder, Sustainion XA-9 ionomer (Dioxide Materials) and ethanol.

[0014] As a further improvement of the present invention, the preparation process of Cu3Pd is as follows: (1) Mix palladium(II) acetylacetone and copper(II) acetate into a 2-ethoxyethanol solution, stir in an ice-water bath, and add sodium borohydride aqueous solution dropwise. (2) The solution color turns brownish-black. The brownish-black product is collected by filtration, washed with water ten times, washed with ethanol twice, and then dried under vacuum at 50°C. (3) The obtained product was annealed in an oxygen-free atmosphere, the temperature was raised to 450℃ and held for 12h, and then cooled to room temperature.

[0015] As a further improvement of the present invention, the bioreactor is inoculated with sodium-dependent Vibrio ( Vibrio natriegens (This refers to the product obtained through domestication and isotope feeding) As a further improvement of the present invention, the sodium-dependent Vibrio ( Vibrio natriegens The domestication and isotope feeding process of ) is as follows: (1) Simulate a high-concentration acetic acid environment in the culture medium, introduce wild-type sodium-dependent Vibrio into this environment, and obtain domesticated sodium-dependent Vibrio strains through continuous subculturing until a stable growth rate is obtained. (2) The domesticated sodium-dependent Vibrio strain was transferred to a culture medium with sodium acetate labeled with isotopes as the sole carbon source for cultivation. Using single-cell Raman activated cell sorting technology and stable isotope detection, the single bacteria with the most active metabolism under acetic acid culture conditions were successfully screened.

[0016] As a further improvement of the present invention, the isotopes in step (2) are D2O and 13 C.

[0017] Secondly, the present invention also provides an application of the above-mentioned electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials in the preparation of long-chain chemicals, wherein the long-chain chemicals include, but are not limited to, acetyl-CoA, ethanol acetaldehyde dehydrogenase, citric acid, fatty acid derivatives produced by acetyl-CoA, and substances such as biomass and recombinant proteins produced by acetyl-CoA entering the TCA cycle.

[0018] The beneficial effects of this invention are as follows: This invention ingeniously integrates two independent but complementary systems—electrocatalysis and bio-fermentation—to form a highly efficient and sustainable bioproduction platform. The electrocatalytic system provides microorganisms with a high-value carbon source (acetate), which in turn efficiently converts these carbon sources into more complex or valuable biological products, achieving a closed-loop process from CO2 to biological products. The entire process uses CO2 and seawater as raw materials, resulting in significant environmental benefits. Attached Figure Description

[0019] Figure 1 The components of the electrochemical-biological coupling system of the present invention; Figure 2 This is a schematic diagram of the connection of the series electrocatalytic system in this invention; Figure 3 This diagram shows the actual equipment composition of the electrochemical-biological coupling system of the present invention and the acetate yield of the tandem catalytic system. Figure 4 Characterization diagram of Cu3Pd, the electroreducible raw material prepared in this invention; Figure 5 A comparison chart of the electrocatalytic performance of different copper-containing catalysts; Figure 6 The graph shows the electrocatalytic performance of a single catalyst, OD-Ag, for CO2-to-CO. Figure 7 This is a schematic diagram of the bioreactor structure of the present invention; Figure 8 The tolerance of the selected strain of *Vibrio natans* to different carbon sources is shown. Figure 9 This invention compares the effects of electrolytes on the growth of Escherichia coli and sodium-dependent Vibrio. Figure 10 This invention describes the isolation of single-celled sodium-dependent Vibrio bacteria that metabolize acetic acid using single-cell Raman sorting technology. Detailed Implementation

[0020] The present application will be described in further detail below with reference to experiments and accompanying drawings. It should be noted that the specific embodiments described below are only for further illustration of the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0021] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products, and all instruments used are conventional instruments known to those skilled in the art.

[0022] like Figure 1As shown, the electrochemical-biological coupling system of this invention comprises at least one tandem electrocatalytic system and at least one bioreactor. The electrolyte containing neutralized acetate, produced by the tandem electrocatalytic system, is pumped into the bioreactor. In the bioreactor, pre-inoculated microorganisms, using acetate as their primary carbon and energy source, proliferate and metabolize under suitable culture conditions (temperature 30°C, pH 6.3-6.5, requiring the introduction of sterile air).

[0023] Microorganisms convert acetate into desired biological products (such as recombinant proteins, bioplastic precursors, fine chemicals, etc.).

[0024] like Figure 2 As shown, the series electrocatalytic system includes two MEA electrolyzers (the electrolytes of the two electrolyzers are 0.1M NaOH and 1M NaOH, respectively). Each MEA electrolyzer includes a cathode electrode, an anode electrode, an ion exchange membrane, a gas diffusion serpentine channel, and a current collector. The cathode electrodes of both MEA electrolyzers are loaded with catalysts. The first-stage catalyst is oxygen-treated nano-silver (OD-Ag) catalyst, and the second-stage catalyst is Cu3Pd catalyst.

[0025] Among them, the cathode electrode (OD-Ag-based GDE cathode and Cu3Pd-based GDE cathode): is located on the CO2 input side of the MEA electrolyzer and is loaded with catalyst.

[0026] Anode electrode (IrO2-coated titanium mesh anode): Located on the other side of the MEA electrolyzer, it is typically used for water oxidation to produce oxygen.

[0027] Ion exchange membrane (or proton exchange membrane): sandwiched between the cathode and anode, used to selectively conduct ions and isolate gaseous products.

[0028] Gas diffusion serpentine channel: located outside the cathode and anode, used for the transport of gases (CO2 and product gases) and the removal of gaseous products.

[0029] Current collector plate: In contact with the gas diffusion layer, used to introduce or drain current into the electrode.

[0030] The oxygen-treated nano-silver (OD-Ag) catalyst is placed adjacent to the cathode gas diffusion serpentine channel and in direct contact with the CO2 inlet. The OD-Ag catalyst can efficiently reduce CO2 to CO, and its "oxygen-rich" properties have been found to effectively promote the activation and reduction of CO2.

[0031] Cu3Pd catalyst: As a second-stage catalyst, it is located adjacent to or connected to the OD-Ag catalyst layer in the CO flow direction of the MEA electrolyzer, so as to receive the CO generated by the OD-Ag catalyst.

[0032] Working principle and process: CO2 entry: Gaseous CO2 enters the cathode side of the MEA electrolyzer from the inlet and diffuses to the OD-Ag catalyst layer through the gas diffusion serpentine channel.

[0033] The first step of reduction (CO2→CO): On the surface of the OD-Ag catalyst, CO2 molecules are adsorbed and accept electrons, undergoing an electrochemical reduction reaction to generate CO.

[0034] This step is mainly carried out in the OD-Ag catalyst layer, which utilizes its unique Ag-O structure to improve the activation of CO2 and the selectivity of CO generation.

[0035] The second step, reduction (CO → acetate): The generated CO then diffuses into the Cu3Pd catalyst layer (or continues to react on the same catalyst layer), where it undergoes further electrochemical coupling reduction on the Cu3Pd catalyst surface to generate acetate. This step utilizes the excellent catalytic activity of the Cu3Pd catalyst for the coupling of CO to C2 products (such as acetate).

[0036] During the electrochemical reduction process, electrons flow from the external circuit to the cathode and participate in the reaction on the catalyst surface. Acetate produced at the cathode and residual CO flow out with the electrolyte or gas. Simultaneously, at the anode, water oxidation occurs to produce oxygen and protons. Protons are transported from the anode to the cathode through the ion exchange membrane to participate in the reduction reaction at the cathode. Acetate (usually dissolved in the electrolyte) and unreacted CO2 and O2 gaseous products are removed from the electrolyzer, with the acetate flowing into the subsequent bioreactor.

[0037] like Figure 3 As shown, the tandem catalytic system of this invention achieves an acetate Faraday efficiency of 48.11% (at 600 mA cm⁻¹). -2 (at current density) and 1.15 μmol s -1 cm -2 Acetate yield (at 1000 mA cm⁻¹) -2 (At current density), it is significantly higher than that of existing technologies.

[0038] Furthermore, the cathode electrode fabrication process in this invention is as follows: (1) Preparation of Cu3Pd catalyst It was prepared by reducing a mixture of palladium(II) acetate and copper(II) acetate with sodium borohydride (NaBH4) (the molar ratio of copper(II):palladium(II) was 5:1).

[0039] The specific steps are as follows: 76.16 mg of palladium acetylacetonate (II) (Pd(acac)2, 0.25 mmol) and 227.0 mg of copper acetate (II) (Cu(CH3COO)2, 1.25 mmol) were mixed in a 2-ethoxyethanol solution. The solution was then stirred in an ice-water bath, and 15 mL of 0.15 mol sodium borohydride aqueous solution was added dropwise. Upon addition, the solution immediately turned brownish-black, indicating alloy formation. The synthesized alloy was collected by filtration, washed ten times with water, twice with ethanol, and then dried under vacuum at 50 °C.

[0040] The obtained nano-alloys were annealed in a 5% hydrogen / argon atmosphere, with the temperature raised to 450°C and held for 12 hours, and then cooled to room temperature.

[0041] The annealed nano-alloys were characterized, such as Figure 4 As shown, Figure 4 Image a shows an aberration-corrected high-angle annular dark-field scanning transmission electron microscope (AC-HAADF-STEM) image of the prepared Cu3Pd nanoparticles. A highly ordered rectangular array is clearly distinguishable in the image, with alternating bright and dark atomic pillars corresponding to heavy Pd ​​and light Cu atoms, respectively, all located within the intermetallic Cu-Pd alloy phase. Further X-ray diffraction (XRD) analysis... Figure 4 b) The analysis results show that the nanoparticles possess an ordered Cu3Pd crystal structure, exhibiting characteristic superlattice diffraction peaks at 23.8° and 34.2°; Rietveld refinement results indicate that the Cu3Pd phase is dominant. Subsequently, X-ray absorption spectroscopy (using Cu2O and metallic Cu as references) was used to characterize the CuK-edge local coordination structure of the nanoalloy. Figure 4 As shown in c, the main scattering path length of Cu-Cu / Pd in ​​Cu3Pd (approximately 2.15 Å) is shorter than that of Cu foil (approximately 2.21 Å), indicating that the material undergoes compressive lattice strain after alloying with Pd.

[0042] (2) Electrode preparation First, 30 mg of carbon black and 90 mg of polytetrafluoroethylene (PTFE) nanoparticles were added to 15 mL of ethanol to prepare PTFE ink. After ultrasonic treatment for 30 minutes, the PTFE ink was air-sprayed onto a gas diffusion electrode (GDE) at 90 °C. After drying, the final C@PTFE loading was 1 mg / cm², yielding an enhanced GDE.

[0043] The cathode was prepared by air-spraying cathode ink onto an enhanced GDE at 120°C. Specifically: Preparation of Cu3Pd ink: Mix 80 mg Cu3Pd, 400 μL Sustainion XA-9 ionomer (Dioxide Materials) and 30 mL ethanol.

[0044] Preparation of OD-Ag ink: OD-Ag (oxide-derived silver) is prepared by O2 plasma treatment of nano-silver powder (≤100 nm, 99.99%, ACMEC), by mixing 60 mg of OD-Ag, 300 μL of Sustainion XA-9 ionomer (Dioxide Materials) and 20 mL of ethanol.

[0045] After drying, the final Cu3Pd and OD-Ag loadings were 0.6 mg / cm² and 0.4 mg / cm², respectively.

[0046] This invention achieves highly efficient and selective conversion from CO2 to C2 products (acetate) through the synergistic effect of an OD-Ag catalyst (efficient CO2 to CO) and a Cu3Pd catalyst (efficient CO to C2 products), overcoming the challenge of a single catalyst failing to simultaneously achieve CO2 activation and C2 coupling. Other catalysts listed in the table below do not achieve the effects described in this invention, such as... Figure 5 As shown, the Cu3Pd catalyst prepared in this invention can efficiently electroreduc CO to acetic acid, with a partial current density reaching 443.9 mA cm⁻¹. -2 This material has reached the top level in the current field. Furthermore, it exhibits exceptional stability, operating stably for 100 hours at ampere-level current densities—a rare stability testing condition reported in this field, as shown in the table below.

[0047]

[0048] This invention achieves highly efficient and selective conversion from CO2 to C2 products (acetate) through the synergistic effect of an OD-Ag catalyst (efficient CO2 to CO) and a Cu3Pd catalyst (efficient CO to C2 products), overcoming the limitations of single catalysts (such as...). Figure 6 As shown, a single OD-Ag catalyst faces the challenge of simultaneously achieving CO2 activation and C2 coupling.

[0049] like Figure 7 As shown, the bioreactor of the present invention is used for the cultivation and fermentation of microorganisms, comprising: Reaction vessel: Used to contain culture medium and microorganisms.

[0050] Stirring device: Ensures uniform mixing of culture medium and microorganisms, promoting mass transfer.

[0051] Ventilation / gas supply device: Provides the necessary oxygen or other gases for microorganisms.

[0052] Temperature control system: Maintains the optimal temperature for microbial growth.

[0053] pH control system: Maintains the optimal pH value for microbial growth.

[0054] The core of the bioreactor in this invention lies in the fact that the microorganisms inoculated in the bioreactor are sodium-dependent Vibrio (NaHCO3). Vibrio natriegens ).

[0055] like Figure 8 As shown, using multiple CO2 electrochemical reduction products such as formaldehyde, formic acid, methanol, acetic acid, and ethanol as the sole carbon source for sodium-dependent Vibrio ( ) Vibrio natriegens Preliminary experiments were conducted to test the growth of *Vibrio natans*. Under the condition that the total carbon concentration was 100 mM (final concentration of C2 product was 50 mM, and final concentration of C1 product was 100 mM), the results showed that acetic acid could effectively promote the growth of sodium-dependent *Vibrio natans* and was identified as an ideal carbon source for the electroreduced CO2 products.

[0056] like Figure 9 As shown, regarding the problem of sodium ions inhibiting the growth of conventional engineered bacteria, this invention compares the effects of sodium ions on Escherichia coli (E. coli). E. coli ) and sodium-dependent Vibrio ( Vibrio natriegens The growth status of *Vibrio natriureticis* was investigated under acetic acid medium and simulated high-salt electrochemical product (e-solution, 50 mM acetic acid with high concentration of NaCl) conditions. The experimental results clearly showed that *Vibrio natriureticis* grew significantly better than *Escherichia coli* under high-salt acetic acid (e-solution) conditions, confirming its potential to utilize acetic acid in a high-salt environment.

[0057] To adapt sodium-dependent Vibrio to a growth environment where acetic acid is used as a carbon source, such as... Figure 10 As shown, wild-type sodium-dependent Vibrio was domesticated and cultured under high-concentration acetic acid conditions. The domesticated bacterial population was fed with isotopes, and single-cell Raman sorting technology was used to screen for the most active single bacteria under acetic acid culture conditions.

[0058] This invention employs an Adaptive Laboratory Evolution (ALE) strategy, using continuous subculturing to adapt wild-type sodium-dependent Vibrio to a high-acetic acid environment. By combining single-cell Raman-activated cell sorting (RACS) with stable isotope probing (SIP), the most metabolically active single bacteria under acetic acid culture conditions were successfully screened. The evolved strains showed a 78.5% increase in biomass within 48 hours, a growth rate more than three times faster than the wild-type strain, and effectively... 13C-labeled acetic acid is converted into carbohydrate metabolites, significantly improving its acetic acid utilization and tolerance to high acetic acid concentrations. The specific steps are as follows: (1) Cultivation and stable propagation Shake flask culture: carried out in M9 basal medium supplemented with acetic acid and ethanol (alone or both as carbon sources) for testing different sodium-dependent Vibrio species. Vibrio natriegens Growth changes of strains.

[0059] Sodium-dependent Vibrio ( Vibrio natriegens The standard growth medium for this product is M9 basal medium, which consists of: Disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O): 15.1 g / L, potassium dihydrogen phosphate (KH2PO4): 3 g / L, ammonium chloride (NH4Cl): 5 g / L, sodium chloride (NaCl): 25 g / L, calcium chloride (CaCl2): 0.011 g / L, magnesium sulfate heptahydrate (MgSO4·7H2O): 0.5 g / L, vitamin B1: 0.2 mL / L (1% W / V solution); Depending on the plasmid vector used, supplement with the following concentrations of antibiotics if necessary: Carbenicillin: 50 μg / mL, Chloramphenicol: 10 μg / mL, Kanamycin: 50 μg / mL, Spectinomycin: 100 μg / mL.

[0060] All experiments were incubated at 30°C and 250 rpm. During incubation, the pH was monitored daily and manually adjusted to between 6.0 and 7.0 with hydrochloric acid.

[0061] For adaptive evolution culture, a single Vibrio colony was selected from solid LBv2 medium (with an additional 20 g / L sodium chloride added to Luria Bertani broth), inoculated into 3 mL of LBv2 medium, and incubated overnight at 30°C. Subsequently, 1% (v / v) of the overnight seed culture was transferred to a 250 mL Erlenmeyer flask containing 50 mL of M9 basal medium supplemented with 50 mM / L sodium acetate as the sole carbon source. The flask was incubated at 30°C with shaking at 200 rpm. The absorbance at 600 nm (OD600) was measured. When the OD600 exceeded 1.5, 1% (v / v) of the culture was transferred to fresh medium. As the Vibrio strain adapted, the concentration of sodium acetate in the medium was gradually increased to 150 mM / L. This continuous subculturing process was carried out for 120 days until a stable growth rate was achieved, yielding an ALE-evolved Vibrio strain.

[0062] The microbial community used in the targeted domestication process often produces several random mutations that result in different genotypes of strains that can adapt to this selection pressure. In order to screen out single cells with stronger acetic acid metabolism capacity from the domesticated microbial community, a subsequent Raman spectroscopy screening is added. By labeling acetic acid or heavy water, the spectral changes of different cells under high concentrations of acetic acid are analyzed to obtain the target strain.

[0063] (2) Single-cell Raman microscopy Wild-type and ALE-evolved Vibrio strains were activated in LBv2 medium and then transferred at a 1:1000 dilution to a medium containing 50% D2O and 100 mM iodine. 13 The culture was performed in M9 basal medium with C-labeled sodium acetate as the sole carbon source for Raman analysis.

[0064] The control sample consisted of wild-type Vibrio cultured in standard M9 medium with unlabeled sodium acetate.

[0065] A confocal Raman microspectrometer (P300, Hauke ​​Instruments Co., Ltd., China) was used, equipped with a 532 nm solid-state laser (50 mW, 1 MHz) and a -70 °C cooled charge-coupled device (CCD) detector (PIXIS100B, Princeton Instruments, USA).

[0066] The spectrum covers a wavenumber range of 400–3600 cm⁻¹, with the CD stretching vibration occurring between 2,040 and 2,300 cm⁻¹. -1 The stretching vibration of CH was observed between 2800 and 3100 cm⁻¹. -1 Identification within the range.

[0067] Raman scattered light was collected using a dry objective lens (Olympus MPlan Achromat, Japan) with a numerical aperture of 0.75 and a magnification of ×100. According to the Rayleigh criterion, these optical properties of the system imply a spatial resolution of 1 micrometer. For a single spectrum, a power of 5 milliwatts at the sample and an exposure time of 10 seconds resulted in a spectral resolution of less than 2 cm⁻¹. -1 Single-cell Raman spectra were recorded and baseline correction was performed using a third-order polynomial to remove cosmic ray interference. All Raman sample measurements were performed on a Raman detection chip (Hauer), which has 50% higher signal acquisition efficiency than CaF2 chips. More than 600 single-cell Raman spectra were acquired for each sample.

[0068] This invention relates to a series electrocatalytic system that electrochemically reduces CO2 to acetate. The electrocatalytic process utilizes oxygen-deficient silver (OD-Ag) and Cu3Pd catalysts, integrated into a membrane electrode assembly (MEA) electrolyzer. The acetate produced by the electrocatalytic system is then introduced into a bioreactor. In the bioreactor, through inoculation... Vibrio natriegens Microorganisms utilize acetate fermentation to produce target bioproducts. The electrochemical-biological coupling system of this invention demonstrates excellent performance in CO2 and seawater treatment and can be widely applied in the production and preparation of long-chain chemicals.

[0069] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. An electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials, characterized in that, include: At least one tandem electrocatalytic system for the electrochemical reduction of CO2 to carbon source products; The series electrocatalytic system includes two MEA electrolyzers connected in series. Each MEA electrolyzer has a cathode electrode and an anode electrode. Both cathode electrodes are loaded with catalysts. According to the processing sequence, the cathode electrode of the first MEA electrolyzer is loaded with an OD-Ag catalyst, and the cathode electrode of the second MEA electrolyzer is loaded with a Cu3Pd catalyst. At least one bioreactor for further producing the target biological product by fermentation using the carbon source and seawater; The microorganisms inoculated in the bioreactor are sodium-dependent Vibrio (NaHCO3). Vibrio natriegens ); The product outlet of each tandem electrocatalytic system is connected to the inlet of the bioreactor.

2. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 1, characterized in that, The MEA electrolyzer also includes an ion exchange membrane, a gas diffusion serpentine channel, and a current collector plate.

3. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 1, characterized in that, The preparation process of the cathode electrode is as follows: (1) Carbon black and polytetrafluoroethylene nanoparticles were added to ethanol to prepare PTFE ink. After ultrasonic treatment, the PTFE ink was sprayed onto the gas diffusion electrode GDE at 90°C and dried to obtain an enhanced GDE. (2) The cathode catalyst ink was air-sprayed onto the enhanced GDE at 120°C and dried to obtain the cathode electrode.

4. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 3, characterized in that, The cathode catalyst ink includes Cu3Pd ink and OD-Ag ink.

5. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 4, characterized in that, The cathode catalyst ink is prepared by mixing Cu3Pd or nano silver powder, Sustainion XA-9 ionomer and ethanol.

6. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 5, characterized in that, The preparation process of Cu3Pd is as follows: (1) Mix palladium(II) acetylacetone and copper(II) acetate into a 2-ethoxyethanol solution, stir in an ice-water bath, and add sodium borohydride aqueous solution dropwise; (2) The solution color turns brownish-black. The brownish-black product is collected by filtration, washed with water ten times, washed with ethanol twice, and then dried under vacuum at 50°C. (3) The obtained product was annealed in an oxygen-free atmosphere, the temperature was raised to 450℃ and held for 12h, and then cooled to room temperature.

7. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 1, characterized in that, The bioreactor was inoculated with sodium-dependent Vibrio ( Vibrio natriegens It was obtained through domestication and isotope feeding.

8. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 1, characterized in that, The sodium-dependent Vibrio ( Vibrio natriegens The domestication and isotope feeding process of ) is as follows: (1) Simulate a high-concentration acetic acid environment in the culture medium, introduce wild-type sodium-dependent Vibrio into this environment, and obtain domesticated sodium-dependent Vibrio strains through continuous subculturing until a stable growth rate is obtained. (2) The domesticated sodium-dependent Vibrio strain was transferred to a culture medium with sodium acetate labeled with isotopes as the sole carbon source for cultivation. Using single-cell Raman activated cell sorting technology and stable isotope detection, the single bacteria with the most active metabolism under acetic acid culture conditions were successfully screened.

9. The electrochemical-biological coupling system based on carbon dioxide and seawater as raw materials according to claim 1, characterized in that, The isotopes in step (2) are D2O and 13 C.

10. The application of the electrochemical-biocoupling system based on carbon dioxide and seawater as raw materials as described in any one of claims 1-9 in the preparation of long-chain chemicals, characterized in that, The long-chain chemicals include, but are not limited to, acetyl-CoA, ethanol acetaldehyde dehydrogenase, citric acid, fatty acid derivatives produced by acetyl-CoA, and biomass and recombinant proteins produced by acetyl-CoA entering the TCA cycle.

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