阅读说明：本技术 一种铵根离子修饰的含氟嵌段共聚物及其应用 (Fluorine-containing block copolymer modified by ammonium ions and application thereof ) 是由 王舜 申传奇 张敏 马嘉露 金辉乐 卢国龙 王武 陈�光 于 2020-12-15 设计创作，主要内容包括：本发明属于微生物燃料电池领域,具体涉及一种铵根离子修饰的含氟嵌段共聚物及其应用。本发明提供的铵根离子修饰的含氟嵌段共聚物可以用于制备微生物燃料电池的粘合剂,具有抗污染性能,减少电极在电池长期运行过程中的受污染程度以及可以减缓催化活性降低的速率,有利于微生物燃料电池长期有效运行,采用本发明提供的粘合剂与碳质催化剂制备的阴极可以替代Pt/C催化剂和Nafion粘合剂组成的阴极,从而降低电池的成本。(The invention belongs to the field of microbial fuel cells, and particularly relates to an ammonium ion modified fluorine-containing block copolymer and application thereof. The fluorine-containing segmented copolymer modified by ammonium ions can be used for preparing the adhesive of the microbial fuel cell, has anti-pollution performance, reduces the pollution degree of an electrode in the long-term operation process of the cell, can slow down the reduction rate of catalytic activity, is beneficial to the long-term effective operation of the microbial fuel cell, and a cathode prepared by the adhesive and the carbonaceous catalyst can replace a cathode consisting of a Pt/C catalyst and a Nafion adhesive, so that the cost of the cell is reduced.)

1. An ammonium ion modified fluorine-containing block copolymer is characterized by having the following chemical formula:

。

2. the method for preparing an ammonium ion-modified fluorine-containing block copolymer according to claim 1, comprising the steps of:

(1) under the protection of nitrogen, adding decafluorobiphenyl, bisphenol A and anhydrous potassium carbonate into a polar aprotic solvent, reacting until the reaction is finished, pouring the reaction liquid into an ethanol hydrochloric acid solution, separating out solids, filtering to obtain granular solids, extracting by using a Soxhlet extractor, and drying to obtain an oligomer containing a difluoride end group; wherein the molar amount of decafluorobiphenyl is greater than the molar amount of bisphenol A;

(2) under the protection of nitrogen, adding decafluorobiphenyl, bisphenol A and anhydrous potassium carbonate into a polar aprotic solvent, reacting until the reaction is finished, pouring the reaction liquid into an ethanol hydrochloric acid solution, separating out solids, filtering to obtain granular solids, extracting by using a Soxhlet extractor, and drying to obtain an oligomer containing bisphenol hydroxyl; wherein the molar amount of decafluorobiphenyl is less than the molar amount of bisphenol A;

(3) dissolving the bisphenol hydroxyl-containing oligomer obtained in the step (2) in tetrachloromethane, adding paraformaldehyde, violently stirring under an ice bath condition, slowly dropwise adding chlorosulfonic acid, heating to 10-20 ℃ for reaction till the end, pouring the reaction liquid into an ethanol hydrochloric acid solution, separating out solids, filtering and drying to obtain a chloromethylation fluorine-containing oligomer;

(4) under the protection of nitrogen, adding the oligomer containing the difluoride end group obtained in the step (1), the chloromethylation fluorine-containing oligomer obtained in the step (3) and potassium carbonate into a polar aprotic solvent, reacting until the reaction is finished, pouring the reaction liquid into ethanol, filtering and drying to obtain a fluorine-containing copolymer;

(5) and (3) soaking the fluorine-containing copolymer obtained in the step (4) into a trimethylamine aqueous solution for quaternization to obtain the fluorine-containing block copolymer modified by ammonium ions.

3. A binder for a microbial fuel cell, characterized by: a fluorine-containing block copolymer modified with ammonium ions according to claim 1.

4. A microbial fuel cell air cathode, characterized by: comprising a cathode catalyst, the binder for a microbial fuel cell according to claim 3, and a current collector, wherein the cathode catalyst is fixed on the current collector by the binder for a microbial fuel cell according to claim 3.

5. The microbial fuel cell air cathode of claim 4, wherein: the cathode catalyst is a carbonaceous catalyst.

6. The microbial fuel cell air cathode of claim 5, wherein: the cathode catalyst is activated carbon.

7. The microbial fuel cell air cathode of claim 4, wherein: and dispersing the cathode catalyst and the adhesive in ethanol or an ethanol water solution to form slurry, dripping, spraying or brushing the slurry on a current collector, and drying to obtain the air cathode of the microbial fuel cell.

8. A microbial fuel cell, characterized by: which employs the microbial fuel cell air cathode of claim 4.

Technical Field

The invention belongs to the field of microbial fuel cells, and particularly relates to an ammonium ion modified fluorine-containing block copolymer and application thereof.

Background

A Microbial Fuel Cell (MFC) is a device that directly converts chemical energy in organic matter into electrical energy using microorganisms. The basic working principle is that under the anaerobic environment of the anode chamber, organic matters are decomposed under the action of microorganisms to release electrons and protons, the electrons are effectively transferred between biological components and the anode by virtue of a proper electron transfer mediator and are transferred to the cathode through an external circuit to form current, the protons are transferred to the cathode through a proton exchange membrane, and an oxidant (generally oxygen) obtains the electrons at the cathode and is reduced to combine with the protons to form water. The materials used in MFC are costly, limiting its range of applications, with the cathode cost being the highest proportion of MFC due to the use of expensive platinum catalysts and Nafion (perfluorosulfonic acid resin) binder solutions.

To avoid the use of expensive platinum-containing catalysts, cathodes with non-precious transition metal alloy catalysts and carbon-based material catalysts have been developed in the prior art, commercial activated carbon has been considered as a promising alternative to Pt/C catalysts for MFCs due to its low cost and catalytic activity compared to most other carbon-based materials, and Activated Carbon (AC) -based cathodes have also been developed to replace Pt/C electrodes by pressing or coating AC onto nickel mesh or stainless steel mesh current collectors, which are cheaper and more conductive than carbon cloth. Although these AC-based cathode MFCs have a maximum power density and maximum cell Capacity (CE) comparable to a battery MFC with a platinum/carbon black (Pt/C) catalyst on a carbon cloth cathode, the corrosion potential of the metal mesh reduces the stability of the cathode, limiting its application to MFCs. In addition to the catalyst, the polymer binder also plays an important role in affecting the performance of the cathode and MFCs because the active catalyst is fixed to the current collector by the polymer binder. The cathode may gradually become fouled over time during long-term operation, resulting in reduced performance because fouling limits electron transfer to the anode and proton transfer to the cathode, or may result in poisoning of the cathode catalyst. Therefore, there is a need for a low cost and antifouling polymeric binder for the preparation of MFC with better performance and which is stable over a long period of time.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide an ammonium ion modified fluorine-containing block copolymer and application thereof.

The first aspect of the present invention provides an ammonium ion modified fluorine-containing block copolymer, which has the following chemical formula:

。

the second aspect of the present invention is a method for preparing the above ammonium ion-modified fluorinated block copolymer, comprising the steps of:

(1) under the protection of nitrogen, adding decafluorobiphenyl, bisphenol A and anhydrous potassium carbonate into a polar aprotic solvent, reacting until the reaction is finished, pouring the reaction liquid into an ethanol hydrochloric acid solution, separating out solids, filtering to obtain granular solids, extracting by using a Soxhlet extractor, and drying to obtain an oligomer containing a difluoride end group; wherein the molar amount of decafluorobiphenyl is greater than the molar amount of bisphenol A;

(2) under the protection of nitrogen, adding decafluorobiphenyl, bisphenol A and anhydrous potassium carbonate into a polar aprotic solvent, reacting until the reaction is finished, pouring the reaction liquid into an ethanol hydrochloric acid solution, separating out solids, filtering to obtain granular solids, extracting by using a Soxhlet extractor, and drying to obtain an oligomer containing bisphenol hydroxyl; wherein the molar amount of decafluorobiphenyl is less than the molar amount of bisphenol A;

(3) dissolving the bisphenol hydroxyl-containing oligomer obtained in the step (2) in tetrachloromethane, adding paraformaldehyde, violently stirring under an ice bath condition, slowly dropwise adding chlorosulfonic acid, heating to 10-20 ℃ for reaction till the end, pouring the reaction liquid into an ethanol hydrochloric acid solution, separating out solids, filtering and drying to obtain a chloromethylation fluorine-containing oligomer;

(4) under the protection of nitrogen, adding the oligomer containing the difluoride end group obtained in the step (1), the chloromethylation fluorine-containing oligomer obtained in the step (3) and potassium carbonate into a polar aprotic solvent, reacting until the reaction is finished, pouring the reaction liquid into ethanol, filtering and drying to obtain a fluorine-containing copolymer;

(5) and (3) soaking the fluorine-containing copolymer obtained in the step (4) into a trimethylamine aqueous solution for quaternization to obtain the fluorine-containing block copolymer modified by ammonium ions.

In a third aspect of the present invention, there is provided a binder for a microbial fuel cell, comprising the ammonium ion-modified fluorine-containing block copolymer as described above.

In a fourth aspect of the present invention, a cathode for a microbial fuel cell is provided, which includes a cathode catalyst, the above adhesive for a microbial fuel cell, and a current collector, wherein the cathode catalyst is fixed on the current collector by the adhesive. The current collector may be any current collector known to those skilled in the art, such as carbon cloth/carbon, metal mesh/metal foam, etc., and the metal mesh/metal foam is commonly nickel mesh, nickel foam, stainless steel mesh, etc.

Preferably, the cathode catalyst is a carbonaceous catalyst. Common carbonaceous catalysts include activated carbon, graphene, carbon nanotubes, carbon nanofibers, and the like, wherein the activated carbon is one of the most common cost-effective carbonaceous catalysts in MFC, and the activated carbon has a rich pore structure and can provide a large specific surface area, active sites, and mass transport channels.

Preferably, the cathode catalyst is activated carbon.

Preferably, the cathode catalyst and the binder are dispersed in ethanol or an ethanol aqueous solution to form slurry, and the slurry is dripped, sprayed or brushed on a current collector and dried to obtain the microbial fuel cell cathode.

In a fifth aspect of the invention, a microbial fuel cell is provided, which employs the microbial fuel cell cathode as described above.

The invention has the following beneficial effects: the fluorine-containing segmented copolymer modified by ammonium ions can be used for preparing the adhesive of the microbial fuel cell, has anti-pollution performance, reduces the pollution degree of an electrode in the long-term operation process of the cell, can slow down the activity reduction rate of a catalyst, is beneficial to the long-term effective operation of the microbial fuel cell, can be used as a substitute with higher cost performance and better stability for a cathode consisting of a Pt/C catalyst and a Nafion adhesive, and reduces the manufacturing cost of the microbial fuel cell.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is within the scope of the present invention for those skilled in the art to obtain other drawings based on the drawings without inventive exercise.

FIG. 1 shows LSV test results;

fig. 2 shows the results of the long-term operation stability test of the battery.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

Example 1:

an ammonium ion modified fluorine-containing block copolymer (Q-FPAE) with the chemical formula as follows:

。

the preparation process comprises the following steps:

(1) in a dry 100ml round bottom three-necked flask equipped with mechanical stirring, condenser and nitrogen inlet and outlet pipes, 3.6752 g (0.011mol) of decafluorobiphenyl, 2.2829 g (0.01mol) of bisphenol A, 3.04 g (0.022mol) of anhydrous potassium carbonate and 12ml of vigorously stirred solution were added in succession and the temperature was raised to 50 deg.f^oAnd C, continuing the reaction for 10 hours to obtain a colorless transparent liquid, cooling to room temperature, diluting with a proper amount of DMSO, and slowly pouring the liquid into the ethanol hydrochloric acid solution to obtain a granular solid. Filtering, extracting the polymer with Soxhlet extractor for 48 hr, 120%^oAnd C, vacuum drying for 12 hours to obtain the oligomer containing the double fluorine end groups.

(2) In the same process, the molar ratio of the decafluorobiphenyl to the bisphenol A is adjusted to be 1:1.1, and the oligomer containing the bisphenol hydroxyl is obtained under the same reaction conditions.

(3) 5.224 g (0.01mol) of bisphenol hydroxyl oligomer is dissolved in 30ml of tetrachloroethane solvent, after full dissolution, 7.8 g (0.026 mol) of paraformaldehyde is added, and the temperature is reduced to 0 ^oCStirring vigorously, slowly dropping 2.5 g of chlorosulfonic acid, heating to 15 deg.C ^oCStirring for 48 hours, slowly pouring the liquid into an ethanol hydrochloric acid solution, and separating out white chloromethylation fluorine-containing oligomer. Filtering and drying for later use.

(4) 6.1940 g (0.01mol) of chloromethylated oligomer, 5.2240 g (0.01mol) of bifluoride end-group oligomer and 3.04 (0.022mol) of potassium carbonate are added into 50ml of dimethyl sulfoxide (DMSO) for copolymerization, the reaction conditions are the same as the step (1), finally, a colorless transparent viscous system is obtained, and the colorless transparent viscous system is cooled and precipitated into ethanol solution to obtain white filamentous solid.

(5) And (3) soaking the polymer obtained in the step (4) into a trimethylamine aqueous solution for 48 hours for quaternization to obtain the fluorine-containing block copolymer modified by ammonium ions.

The cathode (hereinafter referred to as Q-F-AC 9) was prepared by using the Q-FPAE obtained in the above preparation process as a binder, and the preparation process was as follows: the current collector has a diameter of 3cm (area of 7 cm)²) The stainless steel net of (1), the polymer was dissolved in a mixed solvent of ethanol and water at a solid content of 5.0 wt% to obtain a polymerThe solution, 60mg activated carbon dispersed in the polymer solution made a suspension, and 300 μ L of suspension was applied to the electrolyte side of the carbon cloth.

The control group used a cathode (hereinafter referred to as Nafion-AC 9) using Nafion as a binder and Pt as a catalyst.

The electrochemical performance of the prepared cathode was tested as follows:

first, LSV test is carried out in a non-biological reactor at 30 ℃ in 1 mV s^-1Was carried out in a reactor containing 28 mL of 200 mM PBS (18.304 g L)^–1 Na₂HPO₄, 9.808 g L^–1 NaH₂PO₄, 0.13 g L^–1 KCl, 0.31 g L^–1 NH₄Cl, pH = 7), and 7 cm equipped²A platinum circular counter electrode and an Ag/AgCl/3M NaCl reference electrode.

The results of the tests are shown in fig. 1, where AC-containing cathodes containing Q-FPAE binder have lower current densities than Pt/c-based cathodes at the same voltage, the main difference being due to the different catalyst types, Pt having higher oxygen reduction activity than AC. Meanwhile, the AC-containing cathode containing the Q-FPAE binder had a higher current density than the Nafion-AC9 cathode, indicating that the Q-FPAE binder was more favorable for the transport of ions in solution than the Nafion binder, showing a higher electrochemical activity. In comparison, the Q-F-AC9 cathode shows higher cost performance and has the potential of good MFC use.

Two, in the same reactor used for the LSV test at 10⁵Electrochemical Impedance Spectroscopy (EIS) testing was conducted at 0.3V (vs. NHE) to a frequency range of 0.006 Hz with a sinusoidal perturbation of 10 mV and charge transfer resistance calculated from the RC response as shown in table 1, with Pt/C catalyst based cathodes having 2 to 3 times greater charge transfer resistance after 18 cycles of operation and with little change in AC-containing cathodes with Q-FPAE binder. Biofilm was seen on the surface of all cathodes after 18 cycles, but the data in table 1 can indicate that the presence of a significant amount of biofilm on the surface of Q-F-AC9 did not affect the charge transfer resistance (Rct), possibly with the presence of its internal Q-FPAE binder hindering the formation of biofilm or biopolymer within the cathode structure. Thereby can beIt can be seen that the application of the Q-FPAE prepared in the embodiment as a binder in a microbial fuel cell can reduce the surface pollution of the cathode, inhibit the inactivation of the catalyst and help to avoid the performance reduction caused by the long-term use of the cathode.

And thirdly, MFC performance test, using a multimeter and an Ag/AgCl/3M NaCl reference electrode, and measuring the generated voltage (Ecell) and electrode potential at a fixed external circuit resistance (1000 omega). The reactor contains 1 g L^-1Sodium acetate in 50 mM PBS (4.58 g L)^–1 Na₂HPO₄, 2.45 g L^–1 NaH₂PO₄ ^.H₂O, 0.13 g L^–1 KCl, 0.31 g L^–1 NH₄Cl, pH 7, trace minerals and vitamins, conductivity 6.95 mS cm^-1). Each cycle lasted about 2 days, then when the cell voltage generated was below 30 mV, the substrate in the reactor was replaced with fresh solution. After running the reactor on fresh substrates for about 2 hours, polarization and power density curves were plotted as a function of current density using the one-cycle method 13 after 20 minutes at each external resistance (1000-20 Ω).

Over 18 duty cycles, the maximum power density of all MFCs was reduced compared to the power obtained in the initial cycle. This reduction may be due to the formation of a biofilm on the cathode surface and to the adsorption of catalyst surface species that reduce the catalytic activity of the cathode. The degree of performance degradation depends on the catalyst and binder type. MFC with a cathode containing a Pt/C catalyst showed a steady decrease in maximum power density, while MFC with a Q-F-AC9 cathode showed a minimal decrease in power density. Of all the MFCs tested, the cell with the Q-F-AC9 cathode had the highest maximum power density (table 2).

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.