Carbon material-hydrogen bonded organic framework composite electrode and method of making same

Abstract

This invention discloses a carbon material-hydrogen-bonded organic framework composite electrode and its preparation method. The preparation method includes the following steps: synthesizing the hydrogen-bonded organic framework: adding 1,3,6,8-tetra(carboxyphenyl)pyrene to its good solvent, completely dissolving it to form isolated molecules; adding a poor solvent for 1,3,6,8-tetra(carboxyphenyl)pyrene to produce 1,3,6,8-tetra(carboxyphenyl)pyrene crystals, obtaining HOFs-H4TBAPy yellow solid powder; loading HOFs-H4TBAPy onto the surface of ITO conductive glass to obtain ITO@HOFs-H4TBAPy; combining carbon material with ITO@HOFs-H4TBAPy to form an electrical connection, obtaining the carbon material-hydrogen-bonded organic framework composite electrode. This invention can simultaneously generate photocatalytic hydrogen evolution reaction and electrocatalytic hydrogen evolution reaction, accelerating the efficiency of microbial CO2 fixation, thereby improving the performance of MES in producing acetic acid.

Description

Technical Field

[0001] This invention relates to the field of microbial electrosynthesis, and in particular to a carbon material-hydrogen bonded organic framework composite electrode and its preparation method. Background Technology

[0002] Microbial electrosynthesis (MES) has attracted considerable attention from researchers. As a technology in the field of bioelectrochemistry, it integrates techniques and methods from multiple disciplines, including environmental science, biology, and chemistry. MES is a process that utilizes electroautotrophic bacteria (EAB) as a biocatalyst and CO2 as the sole carbon source to metabolize and produce high-carbon compounds under extremely low electrical energy conditions. A key step in this process is electron transfer. Biocatalysts accept electrons in two main ways: direct electron transfer, primarily relying on the physical contact between cell membrane proteins (cytochrome-c, etc.), flagella, and the electrode; and indirect electron transfer, through electron mediators such as H2 and flavin. Since different microorganisms have different cell membrane compositions, indirect electron transfer is the dominant electron transfer mechanism in MES. Therefore, suitable catalysts or electrode materials are needed to promote the generation of electron mediators and accelerate electron transfer efficiency. Furthermore, both catalysts and electrode materials must possess good biocompatibility to better accept electrons and improve MES performance.

[0003] Currently, common photoactive materials used to modify cathodes in MES include heterojunctions containing metal elements such as CuO / g-C3N4, α-Fe2O3 / g-C3N4, Ag3PO4 / g-C3N4, MnFe2O4 / g-C3N4, WO3 / MoO3 / g-C3N4, and CoP-Fe2O3 / g-C3N4. These materials enhance electron-hole pair separation, improve the hydrogen evolution reaction (HER), and promote IET in the system. It is noteworthy that the heterojunctions currently used in MES involve complex formation processes, typically requiring high temperature and pressure; and almost all of them contain metal ions. The biocompatibility of these metal ions and their potential secondary pollution risks remain significant concerns. It must be pointed out that whether using HER catalysts or photocatalysts to modify the electrodes, the interfacial characteristics between microorganisms and the electrodes will be altered. In photocatalytic systems, the microbial biofilm formed on the electrode surface weakens the photoresponse activity. Therefore, a more sustainable strategy should enhance indirect extracellular electron transfer while maintaining close contact between microorganisms and electrodes, thereby increasing acetate yield. Summary of the Invention

[0004] To overcome the aforementioned shortcomings and deficiencies of existing technologies, the present invention aims to provide a carbon-hydrogen-bonded organic framework composite electrode and its preparation method. HOFs-H4TBAPy are loaded onto the surface of ITO conductive glass and then combined with carbon materials to form a carbon-hydrogen-bonded organic framework composite electrode. When applied to microbial electrosynthesis, this electrode can simultaneously generate photocatalytic hydrogen evolution reaction and electrocatalytic hydrogen evolution reaction, accelerating the efficiency of microbial CO2 fixation and thus improving the performance of acetic acid production in MES. The preparation process of this invention is simple, requires minimal equipment, greatly reduces production costs, and the cathode modification material does not contain metal ions, exhibits good biocompatibility, and does not cause secondary pollution, making it environmentally friendly.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing a carbon material-hydrogen bonded organic framework composite electrode, comprising the following steps:

[0007] Synthesis of hydrogen-bonded organic frameworks: 1,3,6,8-tetra(carboxyphenyl)pyrene was added to its good solvent, which completely dissolved to form isolated molecules. Then, a poor solvent for 1,3,6,8-tetra(carboxyphenyl)pyrene was added, which produced 1,3,6,8-tetra(carboxyphenyl)pyrene crystals, resulting in a mixed solution. The mixed solution was filtered, washed, soaked, and dried to obtain HOFs-H4TBAPy yellow solid powder.

[0008] Loading HOFs-H4TBAPy onto the surface of ITO conductive glass: Dissolve HOFs-H4TBAPy yellow solid powder in acetone, sonicate to form a homogeneous mixed solution, drop it onto the surface of ITO glass, and after evaporating the solvent, obtain ITO@HOFs-H4TBAPy.

[0009] Carbon materials are combined with ITO@HOFs-H4TBAPy to form an electrical connection, resulting in a carbon material-hydrogen bonded organic framework composite electrode.

[0010] In some embodiments of the present invention, the carbon material is carbon felt or carbon cloth.

[0011] In some embodiments of the present invention, the combination of carbon material with ITO@HOFs-H4TBAPy specifically includes:

[0012] ITO@HOFs-H4TBAPy is bonded to carbon materials using titanium wires.

[0013] In some embodiments of the present invention, the good solvent is N,N-dimethylformamide; the poor solvent is at least one of anhydrous ethanol and deionized water.

[0014] In some embodiments of the present invention, the undesirable solvent is a solvent obtained by mixing deionized water and anhydrous ethanol in a volume ratio of 1:(0.5~2).

[0015] In some embodiments of the present invention, the loading of the HOFs-H4TBAPy is 0.2 wt% to 0.3 wt%.

[0016] The present invention also provides a carbon material-hydrogen bonded organic framework composite electrode, comprising a carbon material and an ITO conductive glass loaded with a hydrogen bonded organic framework; the ITO conductive glass loaded with a hydrogen bonded organic framework is bonded together with the carbon material to form an electrical connection.

[0017] In some embodiments of the present invention, the carbon material is a carbon felt; the two surfaces of the carbon felt are respectively provided with ITO conductive glass loaded with hydrogen-bonded organic frameworks.

[0018] The present invention also provides a photoelectrocatalytic microbial electrosynthesis system, including an anode, a cathode and a proton exchange membrane; the cathode is the carbon material-hydrogen bonded organic framework composite electrode described above; the proton exchange membrane separates the anode and the cathode, forming a cathode chamber and an anode chamber respectively; the cathode chamber is inoculated with electroautotrophic active microorganisms, and a light source is installed outside the cathode chamber.

[0019] In some embodiments of the present invention, a voltage is applied to the anode and cathode, light is applied to the cathode, and CO2 gas is introduced. The photocatalytic microbial electrosynthesis system undergoes photocatalytic hydrogen evolution reaction and electrocatalytic hydrogen evolution reaction, while simultaneously undergoing bioelectrocatalytic reduction of CO2 to produce acetic acid.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] (1) In this invention, HOFs-H4TBAPy is loaded onto the surface of ITO conductive glass and then combined with carbon materials to form a carbon material-hydrogen bond organic framework composite electrode, which is applied to microbial electrosynthesis. It can simultaneously produce photocatalytic hydrogen evolution reaction and electrocatalytic hydrogen evolution reaction. Furthermore, the introduction of ITO conductive glass weakens the light shielding effect of the electrode biofilm, promotes photocatalytic hydrogen evolution, and accelerates the efficiency of microbial CO2 fixation, thereby improving the performance of MES in producing acetic acid. Its acetic acid yield reaches 6.05 ± 0.25 g / L, which is 2.43 times that of blank carbon felt (2.49 ± 0.04 g / L).

[0022] (2) The preparation process of this invention is simple and has low equipment requirements, which greatly reduces production costs.

[0023] (3) The cathode modification material of the present invention, 1,3,6,8-tetra(carboxyphenyl)pyrene (H4TBAPy), is a planar molecule with a large π-conjugated system and four carboxylic acid groups, and does not contain any metal elements. It has good biocompatibility and does not have secondary pollution problems, making it green and environmentally friendly. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the fabrication process of the CF-ITO@HOFs-H4TBAPy composite electrode according to an embodiment of the present invention.

[0025] Figure 2 The current-time curves of the CF-ITO@HOFs-H4TBAPy electrode and the CF@HOFs-H4TBAPy electrode prepared in Example 1 of the present invention are shown.

[0026] Figure 3 Linear scan voltammetric curves of the CF-ITO@HOFs-H4TBAPy electrode, CF@HOFs-H4TBAPy electrode, and CF electrode prepared in Example 1 of the present invention under no light illumination.

[0027] Figure 4 The image shows the Tafel slope diagrams of the CF-ITO@HOFs-H4TBAPy electrode, CF@HOFs-H4TBAPy electrode, and CF electrode in the absence of illumination, according to Embodiment 1 of the present invention.

[0028] Figure 5 The hydrogen evolution yield of the CF-ITO@HOFs-H4TBAPy electrode, CF@HOFs-H4TBAPy electrode and CF electrode in Example 1 of the present invention.

[0029] Figure 6 The amount of acetic acid produced by the CF-ITO@HOFs-H4TBAPy electrode, CF@HOFs-H4TBAPy electrode, and CF electrode in Example 1 of the present invention.

[0030] Figure 7 The image shows a fluorescence confocal microscope image of L / CF@HOFs-H4TBAPy in Example 1 of the present invention, wherein (a) is a live cell loaded on CF; (b) is the HOFs-H4TBAPy material loaded on CF; and (c) is a combined image of (a) and (b). Detailed Implementation

[0031] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] The method for preparing the carbon material-hydrogen bonded organic framework composite electrode according to an embodiment of the present invention includes the following steps:

[0033] Synthesis of hydrogen-bonded organic frameworks: 1,3,6,8-tetra(carboxyphenyl)pyrene was added to its good solvent, which completely dissolved to form isolated molecules. Then, a poor solvent for 1,3,6,8-tetra(carboxyphenyl)pyrene was added, which produced 1,3,6,8-tetra(carboxyphenyl)pyrene crystals, resulting in a mixed solution. The mixed solution was filtered, washed, soaked, and dried to obtain HOFs-H4TBAPy yellow solid powder.

[0034] Loading HOFs-H4TBAPy onto the surface of ITO conductive glass: Dissolve HOFs-H4TBAPy yellow solid powder in acetone, sonicate to form a homogeneous mixed solution, drop it onto the surface of ITO glass, and after evaporating the solvent, obtain ITO@HOFs-H4TBAPy.

[0035] Carbon materials are combined with ITO@HOFs-H4TBAPy to form an electrical connection, resulting in a carbon material-hydrogen bonded organic framework composite electrode.

[0036] The specific steps are as follows:

[0037] 1. CF Preprocessing

[0038] (1) Before the CF experiment, soak it in 1 Mol hydrochloric acid for 24 hours and rinse it with deionized water until neutral.

[0039] (2) Soak in 1 Mol sodium hydroxide for 24 hours, and rinse with deionized water until neutral. The purpose of soaking in acid and alkali solutions is to remove metal impurities and organic matter that are mixed on the surface of the carbon felt during production and transportation.

[0040] (3) After cleaning, CF is placed in a 60 ℃ oven to dry and is ready for use.

[0041] 2. Synthesis of HOFs-H4TBAPy and composition of the composite electrode

[0042] (1) Add 300 mg of 1,3,6,8-tetra(carboxyphenyl)pyrene to 45 mL of a good solvent (N,N-dimethylformamide, DMF) and sonicate for 10-20 minutes to form a uniform yellow mixed solution. In DMF, 1,3,6,8-tetra(carboxyphenyl)pyrene is completely dissolved to form isolated molecules.

[0043] (2) Anhydrous ethanol and deionized water are unsuitable solvents. When anhydrous ethanol is added to the above solution, 1,3,6,8-tetra(carboxyphenyl)pyrene crystallizes into rod-shaped crystals. When deionized water is added, the hydrogen bonds between 1,3,6,8-tetra(carboxyphenyl)pyrene molecules are very weak, resulting in low crystallization efficiency. Therefore, the crystallization process of HOFs-H4TBAPy can be controlled by adjusting the proportion of unsuitable solvents. 360 mL of a mixture of deionized water and anhydrous ethanol (volume ratio 1:2, 1:1, 2:1) was poured into the mixed solution at 1000 rpm and reacted at 1000 rpm for 6 hours, avoiding light throughout the process.

[0044] (3) Filter the bright yellow mixed solution obtained in the previous step under light-protected conditions, wash the obtained yellow solid with deionized water 3 times, and then wash it with acetone 3 times.

[0045] (4) Soak the yellow solid obtained in the previous step in 500 mL of acetone solution for 60-84 hours. The purpose is to remove the solvent from the micropores of the generated rod-shaped crystals. (Full name: Protect from light)

[0046] (5) After soaking, filter the above mixed solution and dry the obtained yellow solid in a vacuum drying oven at 60 °C for 8 hours under light-protected conditions to obtain HOFs-H4TBAPy yellow solid powder.

[0047] (6) Dissolve the yellow powder obtained above in 45 mL of acetone, sonicate for 30 min to obtain a uniform yellow solution, and drop 200 μL onto the conductive glass in a fume hood. Repeat the dropping three times, with an interval of 1 hour between each drop. After the solvent (acetone) evaporates, HOFs-H4TBAPy will be loaded onto the ITO surface, thus obtaining ITO@HOFs-H4TBAPy.

[0048] (7) The obtained ITO@HOFs-H4TBAPy is bound to CF with titanium wire to obtain CF-ITO@HOFs-H4TBAPy composite electrode.

[0049] 3. Application of supported electrode materials in carbon dioxide fixation in MES systems

[0050] In the MES system, a titanium mesh is used as the anode and the aforementioned CF-ITO@HOFs-H4TBAPy is used as the cathode. A proton exchange membrane separates the anode and cathode. Electroautotrophic active microorganisms are inoculated in the cathode chamber, and a light source (LED light strip) is added outside the cathode chamber with a constant potential of -0.8 ~ -1.2 V vs. Ag / AgCl. CO2 gas is continuously introduced, and CO2 is reduced to acetic acid through bioelectrocatalytic reduction.

[0051] Electroautotrophic microorganisms were obtained by long-term enrichment and domestication of anaerobic sludge under a hydrogen and carbon dioxide atmosphere. The compositions of the catholyte and anolyte are shown in Tables 1-5. The preparation process of the trace element solution is as follows: first, trichloroacetic acid is dissolved in water, and the pH value is adjusted to 6.5 with KOH solution. Then, other substances are added, and finally, the pH value of the trace element solution is adjusted to 7.0 with KOH solvent.

[0052] Table 1. Composition of cathodic liquid

[0053] Composition Content 1 PETC salt solution 50 mL 2 trace element solution 10 mL 3 <![CDATA[L-Cysteine HCl x H2O]]> 0.5 g 4 <![CDATA[NaHCO3]]> 1 g 5 Wolin's vitamin solution (10x) 1 mL 6 DI water 940 mL

[0054] Table 2. Composition of Anodic Solution

[0055]

[0056] Table 3. Composition of PETC salt solution

[0057]

[0058] Table 4. Composition of Trace Element Solution

[0059]

[0060] Table 5. Composition of Microbial Solutions (10x).

[0061]

[0062] In the following embodiments, the carbon felt (CF) used has a specification of 5*5*0.5 cm, and the ITO conductive glass has a specification of 1*4 cm.

[0063] Example 1

[0064] 0.3 g of 1,3,6,8-tetra(carboxyphenyl)pyrene was dissolved in 45 mL of DMF and sonicated for 15 minutes to form a homogeneous yellow solution. The solution was then placed on a magnetic stirrer at 1000 rpm and 360 mL of a mixture of deionized water and anhydrous ethanol (volume ratio: deionized water: anhydrous ethanol = 1:1) was added. After reacting at 1000 rpm for 6 hours, the mixture was filtered to obtain a yellow solid. The yellow solid was washed three times with deionized water, then three times with acetone. After washing, the solid was immersed in 500 mL of acetone for 72 hours to remove residual solvent. Finally, it was filtered and vacuum dried at 60 °C for 8 hours to obtain approximately 280 mg of the product. The resulting bright yellow powder sample is HOFs-H4TBAPy.

[0065] The obtained 0.28 g HOFs-H4TBAPy solid was dissolved in 45 mL acetone and sonicated for 15 min to form a homogeneous mixed solution. 200 μL was dropped onto the surface of an ITO glass and placed in a fume hood for more than one hour to evaporate the solvent. The process was repeated 3 times to finally obtain ITO@HOFs-H4TBAPy with a loading of approximately 0.2 wt%-0.3 wt%.

[0066] The obtained ITO@HOFs-H4TBAPy was bonded to carbon felt using titanium wires. Each carbon felt could be bonded to four ITO@HOFs-H4TBAPy pieces, resulting in a CF-ITO@HOFs-H4TBAPy composite electrode. Figure 1 As shown.

[0067] To better illustrate the advantages of the catalyst composite electrode of the present invention, the following experimental groups were set up in this embodiment to test the electrochemical performance of the catalyst composite electrodes in each experimental group. In the following experiments, the illumination light was an LED light strip:

[0068] The composite electrode assembly of the present invention: The CF-ITO@HOFs-H4TBAPy electrode prepared in this embodiment is the cathode, microorganisms are inoculated in the cathode chamber, a titanium mesh is used as the anode, and a potential of -1.05 V vs. Ag / AgCl is applied between the anode and cathode;

[0069] Modified electrode assembly: CF@HOFs-H4TBAPy is used as the cathode, microorganisms are inoculated in the cathode chamber, and a titanium mesh is used as the anode. A potential of -1.05 V vs. Ag / AgCl is applied between the anode and cathode. The preparation of CF@HOFs-H4TBAPy is as follows: the synthesized HOFs-H4TBAPy is loaded onto the CF surface by solvent evaporation to obtain the CF@HOFs-H4TBAPy modified electrode.

[0070] Blank group: Blank carbon felt CF was used as the cathode, microorganisms were inoculated in the cathode chamber, titanium mesh was used as the anode, and a potential of -1.05 V vs. Ag / AgCl was applied between the anode and cathode.

[0071] Figure 2 The figures show the current-time curves of the CF-ITO@HOFs-H4TBAPy electrode and the CF@HOFs-H4TBAPy electrode prepared in this embodiment. Under illumination, the current response generated by the CF-ITO@HOFs-H4TBAPy electrode is higher than that generated by the modified electrode, which proves that the CF-ITO@HOFs-H4TBAPy electrode has better photoresponse activity.

[0072] Figure 3The figures show the linear sweep voltammetry curves of the CF-ITO@HOFs-H4TBAPy electrode, the CF@HOFs-H4TBAPy electrode, and the CF electrode prepared in this embodiment under no-light conditions. Within the linear sweep range, a larger current response of the electrode indicates higher electrocatalytic activity. Compared with the blank CF and CF@HOFs-H4TBAPy modified electrodes, the current response of the CF-ITO@HOFs-H4TBAPy electrode is significantly improved, indicating that the CF-ITO@HOFs-H4TBAPy electrode can achieve better electrocatalytic performance.

[0073] Figure 4 The Tafel slope diagrams of the CF-ITO@HOFs-H4TBAPy electrode, CF@HOFs-H4TBAPy electrode, and CF electrode prepared in this embodiment are shown in the dark. A smaller Tafel slope indicates better hydrogen evolution performance. The Tafel slope of the CF-ITO@HOFs-H4TBAPy composite electrode (0.066 mV dec) is also shown. -1 The value was significantly smaller than that of the CF@HOFs-H4TBAPy modified electrode (0.14 mVdec). -1 ) and blank CF (0.3 mV dec -1 ).

[0074] Figure 5 The hydrogen evolution yields of the CF-ITO@HOFs-H4TBAPy electrode, CF@HOFs-H4TBAPy electrode, and CF electrode prepared for this embodiment are given. L / CF-ITO@HOFs-H4TBAPy represents the CF-ITO@HOFs-H4TBAPy electrode under illumination; D / CF-ITO@HOFs-H4TBAPy represents the CF-ITO@HOFs-H4TBAPy electrode without illumination; L / CF@HOFs-H4TBAPy represents the CF@HOFs-H4TBAPy electrode under illumination; and D / CF represents the blank carbon felt CF electrode without illumination.

[0075] Figure 6 The acetic acid production of the CF-ITO@HOFs-H4TBAPy electrode, CF@HOFs-H4TBAPy electrode, and CF electrode prepared in this embodiment was measured. The results showed that the acetic acid production of the L / CF@HOFs-H4TBAPy electrode and the D / CF-ITO@HOFs-H4TBAPy electrode was very similar after one week of operation. Therefore, the reaction was terminated after one week, and the cathode biofilm of the modified electrodes was collected. After staining with the SYTO 9 / PI dead / live cell kit, the L / CF@HOFs-H4TBAPy electrode was observed by fluorescence confocal microscopy. Figure 7It was found that the formed microbial attachment layer significantly covered the photocatalyst directly deposited on the CF substrate, and the resulting light-blocking effect weakened its photocatalytic performance. This is also one of the reasons for its poor acetic acid production performance. After 15 days of continuous carbon dioxide purging, the reactors of the composite electrode group and the blank CF group showed the highest final concentration with the L / CF-ITO@HOFs-H4TBAPy composite electrode group, achieving an acetic acid concentration of 6.05 ± 0.25 g L. -1 The concentration of acetic acid in the blank CF was only (2.49 ± 0.04 g L). -1 This indicates that L / CF-ITO@HOFs-H4TBAPy has significant advantages in promoting acetate formation and maintaining hydrogen evolution, highlighting its high efficiency and application potential in relevant reaction systems.

[0076] Example 2

[0077] 0.3 g of 1,3,6,8-tetra(carboxyphenyl)pyrene was dissolved in 45 mL of DMF and sonicated for 15 minutes to form a homogeneous yellow solution. The solution was then placed on a magnetic stirrer at 1000 rpm and 360 mL of a mixture of deionized water and anhydrous ethanol (volume ratio: deionized water: anhydrous ethanol = 1:1) was added. After reacting at 1000 rpm for 6 hours, the mixture was filtered to obtain a yellow solid. The yellow solid was washed three times with deionized water, then three times with acetone. After washing, the solid was immersed in 500 mL of acetone for 72 hours to remove residual solvent. Finally, the solid was filtered and vacuum dried at 60 °C for 8 hours to obtain approximately 280 mg of the product. The resulting bright yellow powder sample is HOFs-H4TBAPy.

[0078] The obtained HOFs-H4TBAPy solid was dissolved in 45 mL of acetone and sonicated for 5 min to form a homogeneous mixed solution. 200 μL was dropped onto the surface of an ITO glass and placed in a fume hood for more than one hour to evaporate the solvent. The process was repeated 3 times to finally obtain ITO@HOFs-H4TBAPy with a loading of about 0.2 wt%-0.3 wt%.

[0079] The obtained ITO@HOFs-H4TBAPy is bonded to carbon cloth using titanium wire. Each piece of carbon cloth can be bonded to 4 pieces of ITO@HOFs-H4TBAPy to obtain a carbon cloth-ITO@HOFs-H4TBAPy composite electrode.

[0080] The composite electrode was applied to the MES system under the same conditions as in Example 1, and the final acetate concentration reached 5.83 ± 0.15 g / L. -1 .

[0081] Example 3

[0082] 0.3 g of 1,3,6,8-tetra(carboxyphenyl)pyrene was dissolved in 45 mL of DMF and sonicated for 15 minutes to form a homogeneous yellow solution. The solution was then placed on a magnetic stirrer at 1000 rpm and 360 mL of a mixture of deionized water and anhydrous ethanol (volume ratio: deionized water: anhydrous ethanol = 1:2) was added. After reacting at 1000 rpm for 6 hours, the mixture was filtered to obtain a yellow solid. The yellow solid was washed three times with deionized water, then three times with acetone. After washing, the solid was immersed in 500 mL of acetone for 72 hours to remove residual solvent. Finally, the solid was filtered and vacuum dried at 60 °C for 8 hours to obtain approximately 280 mg of the product. The resulting bright yellow powder sample is HOFs-H4TBAPy.

[0083] The obtained HOFs-H4TBAPy solid was dissolved in 45 mL of acetone and sonicated for 5 min to form a homogeneous mixed solution. 200 μL was dropped onto the surface of an ITO glass and placed in a fume hood for more than one hour to evaporate the solvent. The process was repeated 3 times to finally obtain ITO@HOFs-H4TBAPy with a loading of about 0.2 wt%-0.3 wt%.

[0084] The obtained ITO@HOFs-H4TBAPy is bonded to carbon cloth using titanium wire. Each piece of carbon cloth can be bonded to 4 pieces of ITO@HOFs-H4TBAPy to obtain a carbon cloth-ITO@HOFs-H4TBAPy composite electrode.

[0085] The composite electrode was applied to the MES system under the same conditions as in Example 1, and the final acetate concentration reached 5.91 ± 0.16 g / L. -1 .

[0086] Example 4

[0087] 0.3 g of 1,3,6,8-tetra(carboxyphenyl)pyrene was dissolved in 45 mL of DMF and sonicated for 15 minutes to form a homogeneous yellow solution. The solution was then placed on a magnetic stirrer at 1000 rpm and 360 mL of a mixture of deionized water and anhydrous ethanol (volume ratio: deionized water: anhydrous ethanol = 2:1) was added. After reacting at 1000 rpm for 6 hours, the mixture was filtered to obtain a yellow solid. The yellow solid was washed three times with deionized water, then three times with acetone. After washing, the solid was immersed in 500 mL of acetone for 72 hours to remove residual solvent. Finally, the solid was filtered and vacuum dried at 60 °C for 8 hours to obtain approximately 280 mg of the product. The resulting bright yellow powder sample is HOFs-H4TBAPy.

[0088] The obtained HOFs-H4TBAPy solid was dissolved in 45 mL of acetone and sonicated for 5 min to form a homogeneous mixed solution. 200 μL was dropped onto the surface of an ITO glass and placed in a fume hood for more than one hour to evaporate the solvent. The process was repeated 3 times to finally obtain ITO@HOFs-H4TBAPy with a loading of about 0.2 wt%-0.3 wt%.

[0089] The obtained ITO@HOFs-H4TBAPy is bonded to carbon cloth using titanium wire. Each piece of carbon cloth can be bonded to 4 pieces of ITO@HOFs-H4TBAPy to obtain a carbon cloth-ITO@HOFs-H4TBAPy composite electrode.

[0090] The composite electrode was applied to the MES system under the same conditions as in Example 1, and the final acetate concentration reached 5.94 ± 0.11 g / L. -1 .

[0091] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon material-hydrogen bonded organic framework composite electrode, characterized in that, Includes the following steps: Synthesis of hydrogen-bonded organic frameworks: 1,3,6,8-tetra(carboxyphenyl)pyrene was added to its good solvent, which completely dissolved to form isolated molecules. Then, a poor solvent for 1,3,6,8-tetra(carboxyphenyl)pyrene was added, which produced 1,3,6,8-tetra(carboxyphenyl)pyrene crystals, resulting in a mixed solution. The mixed solution was filtered, washed, soaked, and dried to obtain HOFs-H4TBAPy yellow solid powder. Loading HOFs-H4TBAPy onto the surface of ITO conductive glass: Dissolve HOFs-H4TBAPy yellow solid powder in acetone, sonicate to form a homogeneous mixed solution, drop it onto the surface of ITO glass, and after evaporating the solvent, obtain ITO@HOFs-H4TBAPy. Carbon materials are combined with ITO@HOFs-H4TBAPy to form an electrical connection, resulting in a carbon material-hydrogen bonded organic framework composite electrode.

2. The method for preparing the carbon material-hydrogen bonded organic framework composite electrode according to claim 1, characterized in that, The carbon material is carbon felt or carbon cloth.

3. The method for preparing the carbon material-hydrogen bonded organic framework composite electrode according to claim 2, characterized in that, The specific steps of combining carbon materials with ITO@HOFs-H4TBAPy are as follows: ITO@HOFs-H4TBAPy is bonded to carbon materials using titanium wires.

4. The method for preparing the carbon material-hydrogen bonded organic framework composite electrode according to claim 1, characterized in that, The good solvent is N,N-dimethylformamide; the poor solvent is at least one of anhydrous ethanol and deionized water.

5. The method for preparing the carbon material-hydrogen bonded organic framework composite electrode according to claim 1, characterized in that, The undesirable solvent is a solvent obtained by mixing deionized water and anhydrous ethanol in a volume ratio of 1:(0.5~2).

6. The method for preparing the carbon material-hydrogen bonded organic framework composite electrode according to claim 1, characterized in that, The loading of the HOFs-H4TBAPy is 0.2 wt%~0.3 wt%.

7. A carbon material-hydrogen bonded organic framework composite electrode, characterized in that, The invention comprises a carbon material and an ITO conductive glass loaded with a hydrogen-bonded organic framework; the ITO conductive glass loaded with the hydrogen-bonded organic framework is bonded to the carbon material to form an electrical connection.

8. The carbon material-hydrogen bonded organic framework composite electrode according to claim 7, characterized in that, The carbon material is a carbon felt; the two surfaces of the carbon felt are respectively provided with ITO conductive glass loaded with hydrogen-bonded organic frameworks.

9. A photoelectrocatalytic microbial electrosynthesis system, characterized in that, It includes an anode, a cathode, and a proton exchange membrane; the cathode is a carbon material-hydrogen bonded organic framework composite electrode as described in claim 7 or 8; the proton exchange membrane separates the anode and the cathode, forming a cathode chamber and an anode chamber respectively; the cathode chamber is inoculated with electroautotrophic active microorganisms, and a light source is installed outside the cathode chamber.

10. The photoelectrocatalytic microbial electrosynthesis system according to claim 9, characterized in that, When a voltage is applied to the anode and cathode, light is applied to the cathode, and CO2 gas is introduced, the photocatalytic microbial electrosynthesis system undergoes photocatalytic hydrogen evolution reaction and electrocatalytic hydrogen evolution reaction, while simultaneously undergoing bioelectrocatalytic reduction of CO2 to produce acetic acid.

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