A cyanobacterial carbon quantum dot modified gas diffusion electrode, a preparation method and application thereof

Abstract

The application discloses a cyanobacteria carbon quantum dot modified gas diffusion electrode and a preparation method and application thereof, and belongs to the technical field of environmental engineering. The cyanobacteria carbon quantum dot modified gas diffusion electrode is prepared by taking nitrogen-rich cyanobacteria as a precursor, preparing nitrogen self-doped cyanobacteria carbon quantum dots (BGA-CQDs) by a hydrothermal method as electrode modification material, further mixing the cyanobacteria carbon quantum dots with carbon black, polytetrafluoroethylene (PTFE) and anhydrous ethanol to prepare a uniform catalyst slurry, and coating the catalyst slurry on a pretreated carbon felt base material to obtain the cyanobacteria carbon quantum dot modified gas diffusion electrode (CQDs-GDE). After the cyanobacteria carbon quantum dot modified gas diffusion electrode is applied to an electro-Fenton system, TCPP in water can be efficiently degraded.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering technology, specifically relating to a gas diffusion electrode modified with cyanobacteria carbon quantum dots, its preparation method, and its application. Background Technology

[0002] TCPP (Tris(2-chloropropyl) phosphate), a chlorinated organophosphate compound, is widely used in various industrial fields such as flame retardants, plasticizers, and lubricants. However, the widespread use of TCPP leads to its continuous release into the environment, particularly water, soil, and air, through volatilization and leakage, causing serious environmental pollution. TCPP has significant endocrine-disrupting effects, reproductive toxicity, and long-term ecological risks. Moreover, its molecular structure contains stable C-Cl bonds and a phosphate ester skeleton, resulting in high chemical stability, making it difficult to achieve effective removal using conventional biodegradation and photocatalytic technologies.

[0003] Electro-Fenton (EF) technology, as an advanced oxidation technology, has shown broad application prospects in the treatment of recalcitrant organic pollutants due to its advantages such as simple operation, low energy consumption, and the ability to generate strong oxidizing hydroxyl radicals (·OH) in situ. Its core reaction mechanism involves the generation of hydrogen peroxide (H₂O₂) through a cathode oxygen reduction reaction, which then reacts with Fe in the system. 2+ The Fenton reaction occurs, efficiently generating ·OH to destroy the molecular structure of pollutants.

[0004] Gas diffusion electrodes (GDEs), as the core cathode component of electro-Fenton systems, have become a research hotspot in this field due to their unique gas-liquid-solid three-phase interface structure, which efficiently promotes oxygen diffusion and reduction and significantly improves H2O2 generation efficiency. However, traditional GDEs still have inherent defects: a limited number of surface active sites and low electron transport efficiency, which limits their catalytic performance and makes it difficult to meet the requirements for efficient degradation of stubborn pollutants such as TCPP. Therefore, it is urgent to improve their electrochemical performance through surface modification.

[0005] Carbon quantum dots (CQDs), a novel type of carbon nanomaterial with a size of less than 10 nm, are considered ideal electrode modification materials due to their excellent electron transport properties, abundant surface functional groups, and good dispersibility. Currently, the preparation of CQDs mostly uses small molecule compounds such as citric acid and phenylalanine as precursors, which not only results in high preparation costs but also requires the addition of nitrogen and sulfur dopants to enhance their catalytic activity, undoubtedly increasing the complexity and cost of the preparation process. Meanwhile, cyanobacteria, as a large amount of biomass waste accumulated in eutrophic waters, with annual emissions reaching millions of tons, contain abundant nitrogen-containing biomolecules such as proteins and nucleic acids. Using cyanobacteria as a precursor to prepare carbon quantum dots allows for in-situ self-doping of nitrogen without the need for additional dopants, reducing preparation costs and enabling the resource utilization of cyanobacteria waste, aligning with the environmental protection concept of "treating waste with waste." Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of traditional GDE catalytic activity, high preparation cost and additional doping required for traditional CQDs, and the difficulty in degradation of TCPP, and to provide a method for preparing a gas diffusion electrode modified with cyanobacterial carbon quantum dots.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a gas diffusion electrode modified with cyanobacteria carbon quantum dots, comprising, Cyanobacteria powder was uniformly dispersed in ultrapure water, and the resulting cyanobacteria dispersion was subjected to a hydrothermal reaction to synthesize pre-carbon quantum dots; after cooling, it was purified and dried to obtain cyanobacteria carbon quantum dots, denoted as BGA-CQDs. BGA-CQDs, PTFE, carbon black and anhydrous ethanol are mixed evenly to obtain an electrode slurry. The electrode slurry is coated on an electrode substrate and dried and calcined to obtain a cyanobacterial carbon quantum dot modified gas diffusion electrode, denoted as CQDs-GDE. The hydrothermal reaction temperature is 150~200℃, and the hydrothermal reaction time is 8~15h.

[0010] In a preferred embodiment of the method for preparing the cyanobacterial carbon quantum dot modified gas diffusion electrode of the present invention, the cyanobacterial powder has a particle size of 80-100 mesh and the concentration of the cyanobacterial dispersion is 10 wt.%.

[0011] As a preferred embodiment of the preparation method of the cyanobacterial carbon quantum dot modified gas diffusion electrode of the present invention, the purification is carried out by first filtering through a microporous membrane, then collecting the filtrate and transferring it into a dialysis bag with a molecular weight cutoff of 3500 Da, and dialyzing in ultrapure water for 48-72 hours; wherein the ultrapure water is replaced every 12 hours during the dialysis process.

[0012] In a preferred embodiment of the preparation method of the cyanobacterial carbon quantum dot modified gas diffusion electrode of the present invention, the mass ratio of BGA-CQDs, carbon black and PTFE in the electrode slurry is 0.01~0.05∶0.1∶0.06, and the mass-volume ratio of BGA-CQDs to anhydrous ethanol is 0.01~0.05g∶3mL.

[0013] In a preferred embodiment of the method for preparing the cyanobacterial carbon quantum dot-modified gas diffusion electrode of the present invention, the electrode substrate is a pretreated carbon felt.

[0014] As a preferred embodiment of the preparation method of the gas diffusion electrode modified with cyanobacteria carbon quantum dots according to the present invention, the pretreatment is to ultrasonically clean with deionized water and ethanol for 15 min in sequence, dry it, immerse it in 2wt% polytetrafluoroethylene suspension for 10 min, and then calcine it.

[0015] In a preferred embodiment of the method for preparing the gas diffusion electrode modified with cyanobacteria carbon quantum dots according to the present invention, the calcination is carried out at a temperature of 330~380℃ for a time of 30~60min.

[0016] Another objective of this invention is to overcome the shortcomings of traditional GDEs (low catalytic activity), traditional CQDs (high preparation cost and additional doping required), and TCPP (difficult degradation), and to provide a gas diffusion electrode modified with cyanobacterial carbon quantum dots.

[0017] Another objective of this invention is to overcome the shortcomings of traditional GDE catalytic activity, high cost and additional doping requirements in the preparation of traditional CQDs, and the poor degradation of TCPP, and to provide an application of a cyanobacterial carbon quantum dot-modified gas diffusion electrode for the efficient degradation of organic pollutants in an electro-Fenton system. This includes... Using an iron plate as the anode and the aforementioned CQDs-GDE as the cathode, anhydrous sodium sulfate with a concentration of 50~500mM was added as an electrolyte to wastewater containing organic pollutants, and degradation was carried out by passing electricity. The concentration of the organic pollutant is 100-500 mg / L, and the organic pollutant includes TCPP; the electrode spacing is 10 mm; during the degradation process, the aeration rate is 0-200 mL / min; and the applied current density is 5-25 mA / cm². 2The pH range is 3 to 7.

[0018] As a preferred embodiment of the application of the cyanobacterial carbon quantum dot modified gas diffusion electrode of the present invention in the electro-Fenton system for the efficient degradation of organic pollutants, wherein: the TCPP removal rate of the CQDs-GDE is ≥83%, it has good structural stability and reusability, and after 6 cycles, it still maintains a removal effect of more than 70%.

[0019] Beneficial effects of this invention: (1) The CQDs-GDE used in this invention has a good catalytic effect and can be used as a cathode material for wastewater treatment; (2) This invention uses cyanobacteria, a pollutant in water bodies, as raw material to prepare cyanobacterial carbon quantum dot cathode materials, so that they can be utilized as resources and realize "waste treatment".

[0020] (3) The present invention uses CQDs-GDE cathode material to construct an electro-Fenton system to treat TCPP wastewater. By adjusting the parameters, it can efficiently degrade high-concentration TCPP wastewater, and the removal rate is maintained at more than 85%. At the same time, the electrode itself can be reused. After being repeated 5 times, it can still maintain a removal effect of more than 80%. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments 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. Wherein: Figure 1 This is a particle size distribution diagram of the cyanobacterial carbon quantum dots in Example 1.

[0022] Figure 2 This is a SEM image of CQDs-GDE in Example 1.

[0023] Figure 3 The image shows the recycling effect of the CQDs-GDE prepared in Example 1.

[0024] Figure 4 This is a diagram showing the effect of recycling unmodified GDE.

[0025] Figure 5 A schematic diagram of the fabrication process for a gas diffusion electrode modified with carbon quantum dots from cyanobacteria.

[0026] Figure 6 The graph shows the degradation effect of TCPP at different pH values.

[0027] Figure 7The graph shows the degradation effect of different electrolyte concentrations on TCPP.

[0028] Figure 8 The graph shows the degradation effect of different aeration rates on TCPP.

[0029] Figure 9 The graph shows the degradation effect of different TCPP concentrations on TCPP.

[0030] Figure 10 The graph shows the degradation effect of different current densities on TCPP. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0034] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0035] The removal rate of TCPP is reflected by testing the COD removal rate. The COD measurement method is in accordance with HJ / T399-2007, and the COD removal rate calculation formula is as follows: , Where R: removal rate (%); C0: initial concentration (mg / L); Ce: concentration after treatment (mg / L).

[0036] Example 1

[0037] This embodiment provides a gas diffusion electrode modified with cyanobacteria carbon quantum dots and uses it as a cathode material for wastewater treatment, specifically: 1) Take eutrophic blue-green algae from Taihu Lake, filter it with a 500-mesh nylon filter to remove impurities; put the dried blue-green algae into a 105℃ forced-air drying oven to dry for 24 hours, take it out and grind it for 30 minutes, and pass it through an 80-mesh standard sieve to obtain blue-green algae powder. 2) Weigh 15g of cyanobacteria powder, add 150mL of ultrapure water, disperse completely, transfer to a 200mL polytetrafluoroethylene-lined reactor, seal, and react at 180℃ for 12h. After the reaction, wait for the reactor to cool to room temperature, remove the product and filter it through a 0.22μm aqueous filter membrane, collect the filtrate, put the filtrate into a dialysis bag (molecular weight cutoff 3500Da), and dialyze it in ultrapure water for 72h (replace the ultrapure water every 12h). Place the dialyzed solution in a -70℃ freeze dryer for 12h, and then vacuum dry for 72h to obtain pale yellow cyanobacteria carbon quantum dot powder, denoted as BGA-CQDs.

[0038] 3) Cut the carbon felt to a size of 2cm×5cm, put it into deionized water for ultrasonic cleaning for 15min, take it out and replace it with ethanol for another 15min of ultrasonic cleaning, and dry it at 60℃; immerse the cleaned carbon felt in 2wt% PTFE suspension, let it stand for 10min, take it out and drain the excess liquid, put it in a muffle furnace and calcine at 360℃ for 30min, and cool it naturally to room temperature to obtain pretreated carbon felt. 4) Weigh 0.05g BGA-CQDs, 0.1g carbon black, 3mL anhydrous ethanol and 0.06g PTFE, and ultrasonically disperse for 30min to form a uniform slurry; coat the slurry evenly on the surface of the pretreated carbon felt, and dry it in an 80℃ oven for 12h; calcine the dried electrode at 360℃ for 30min, and obtain CQDs-GDE after cooling.

[0039] The obtained BGA-CQDs were tested, and the test results are as follows: Figure 1 .from Figure 1 It can be seen that the carbon quantum dots from cyanobacteria have a small particle size, mainly concentrated in the range of 1.5~2.5 nm, and the lattice stripes can be clearly observed by TEM, proving that they have a certain degree of crystallinity, which is conducive to electron transport.

[0040] The obtained CQDs-GDE was tested, and the test results are as follows: Figure 2 .from Figure 2 It can be seen that by uniformly loading cyanobacterial carbon quantum dots onto the surface of GDE through coating, a denser composite catalytic layer is formed, increasing the exposure of active sites.

[0041] CQDs-GDE was applied in an electro-Fenton system for TCPP degradation. After each reaction, the CQDs-GDE was rinsed three times with deionized water, dried, and reused for the next reaction, for a total of six cycles. The TCPP removal rate was tested after each cycle, and the electrode cycling stability was also tested. The test results are as follows: Figure 3 The results showed that the TCPP removal rates after 6 cycles were 90.89%, 89.31%, 87.78%, 81.91%, 78.47%, and 70.09%, respectively, indicating that the electrode has good structural stability and reusability.

[0042] Example 2

[0043] The difference between this embodiment and embodiment 1 is that the temperature of the hydrothermal reaction in step 2) is adjusted to 150°C, while the rest of the preparation process is the same as in embodiment 1, and the electrode material is obtained.

[0044] Example 3

[0045] The difference between this embodiment and embodiment 1 is that the temperature of the hydrothermal reaction in step 2) is adjusted to 200°C, while the rest of the preparation process is the same as in embodiment 1, and the electrode material is obtained.

[0046] Example 4

[0047] The difference between this embodiment and embodiment 1 is that the hydrothermal reaction time in step 2) is adjusted to 8 hours, while the rest of the preparation process is the same as in embodiment 1, and the electrode material is obtained.

[0048] Example 5

[0049] The difference between this embodiment and embodiment 1 is that the hydrothermal reaction time in step 2) is adjusted to 15 hours, while the rest of the preparation process is the same as in embodiment 1, and the electrode material is obtained.

[0050] Comparative Example 1

[0051] This comparative example uses traditional GDE, differing from Example 1 in that BGA-CQDs are not added. All other preparation processes are the same as in Example 1, yielding the electrode material. Specifically: Cut the carbon felt to a size of 2cm×5cm, put it into deionized water for ultrasonic cleaning for 15min, take it out and replace it with ethanol for another 15min of ultrasonic cleaning, and dry it at 60℃; immerse the cleaned carbon felt in 2wt% PTFE suspension, let it stand for 10min, take it out and drain the excess liquid, put it in a muffle furnace and calcine at 360℃ for 30min, and cool it naturally to room temperature to obtain pretreated carbon felt. Weigh 0.1g carbon black, 3mL anhydrous ethanol and 0.06g PTFE, and ultrasonically disperse for 30min to form a uniform slurry; coat the slurry evenly on the surface of the pretreated carbon felt, and dry it in an 80℃ oven for 12h; place the dried electrode in a muffle furnace, calcine at 360℃ for 30min, and obtain GDE after cooling.

[0052] Figure 4 The image shows the effect of recycling unmodified GDE. As the number of cycles increases (1~4 times), the TCPP removal rate decreases significantly, and the reuse performance is significantly inferior to that of CQDs-GDE modified with cyanobacterial carbon quantum dots, highlighting the role of cyanobacterial carbon quantum dot modification in improving the cycling stability of the electrode.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 1 is that the BGA-CQDs were changed to carbon citrate quantum dots; all other preparation processes were the same as in Example 1 to obtain the electrode material. Specifically: Citric acid carbon quantum dots were prepared using 15g citric acid and 3g urea as precursors, and then citric acid carbon quantum dots were used to modify GDE.

[0055] CQDs-GDE was applied to an electro-Fenton system at pH 3 and 10 mA / cm². 2 Under the specified conditions, TCPP was degraded, and the measured TCPP removal rates are shown in the table below.

[0056] Table 1

[0057] As shown in the table above, the cyanobacterial carbon quantum dot-modified gas diffusion electrode (CQDs-GDE) provided by this invention exhibits good catalytic performance and can be used as a cathode material for wastewater treatment. When used for wastewater treatment, the TCPP removal rate remains above 85%, reaching a maximum of 93.19%. Furthermore, the electrode itself is reusable; even after five repetitions, it still maintains a removal efficiency of over 80%.

[0058] Different parameter conditions have a significant impact on the application of CQDs-GDE electrodes in the electro-Fenton system for TCPP degradation, and it is necessary to select appropriate parameter conditions to achieve the best treatment effect.

[0059] Example 6

[0060] This embodiment provides a method for the efficient degradation of the organic pollutant TCPP using CQDs-GDE in an electro-Fenton system. The process is as follows: Figure 5 Specifically: Using 100 mg / L TCPP wastewater as the treatment target, 50 mM sodium sulfate was added; an iron plate was used as the anode, and the CQDs-GDE prepared in Example 1 above was used as the cathode; a DC power supply was used as the power source, with a current density of 10 mA / cm². 2 The aeration rate was 100 mL / min, the stirring speed was maintained at 300 rpm throughout the process, the pH was 3, and the experimental time was 3 h; the TCPP degradation reaction was carried out.

[0061] Example 7

[0062] The difference between this embodiment and the previous embodiment is that the pH was adjusted to 4, 5, 6, and 7 respectively, while the rest of the preparation process was the same as the previous embodiment, and TCPP degradation was carried out.

[0063] The results are as follows Figure 6As shown, different pH values ​​have a significant impact on the degradation effect. Within pH ranges of 3-7, the TCPP removal rate increases with increasing reaction time, with a faster increase in the early stages and a slower increase in the later stages. At pH 3, the degradation effect is better than in other acidic or alkaline environments, reaching a maximum removal rate of 91.17% at the end of the degradation experiment. As the pH increases, the degradation effect gradually decreases, with the lowest removal rate among all groups at pH 7. This may be because the core of the electro-Fenton reaction is the Fenton reagent (Fe... 2+ The reaction generates hydroxyl radicals (·OH) from H₂O₂, and this reaction is most efficient under acidic conditions (pH 2-4). Alkaline conditions lead to Fe²⁺... + Hydrolysis forms hydroxide precipitates, which reduce catalytic activity; therefore, pH 3 is the optimal reaction condition.

[0064] Example 8

[0065] The difference between this embodiment and the previous embodiment is that the electrolyte concentration was adjusted to 100, 200, 300, and 500 mM, respectively. The rest of the preparation process was the same as the previous embodiment, and TCPP degradation was carried out.

[0066] The degradation effect of TCPP under different electrolyte concentrations is shown in the figure below. Figure 7 As shown, when the concentration of anhydrous sodium sulfate electrolyte is in the range of 50-500 mM, the TCPP removal rate increases with the extension of reaction time, and the degradation curves of each concentration group show little overall difference. With increasing electrolyte concentration, the TCPP removal rate does not show a significant increase and even shows a slight decreasing trend. The main function of sodium sulfate as an electrolyte is to improve the conductivity of wastewater and promote electron transport on the electrode surface. However, excessive electrolyte ions can compete with ·OH groups for energy or adsorb onto the active sites of the electrode, thus slightly inhibiting the degradation reaction. Therefore, a low concentration of electrolyte is sufficient to meet the reaction requirements.

[0067] Example 9

[0068] The difference between this embodiment and the previous embodiment is that the aeration rate was adjusted to 0, 50, 100, and 150 mL / min, while the rest of the preparation process was the same as the previous embodiment, and TCPP degradation was carried out.

[0069] Figure 8The graph shows the degradation effect of different aeration rates on TCPP. Within the aeration rate range of 0–200 mL / min, the TCPP removal rate continuously increased with the extension of reaction time, and the degradation effect of the aerated group was better than that of the non-aerated group. The degradation effect was optimal at an aeration rate of 100–150 mL / min; when the aeration rate exceeded 150 mL / min, the removal rate did not improve significantly and even decreased slightly. The role of aeration is to provide sufficient O2 for the cathode oxygen reduction reaction to generate H2O2, so moderate aeration can improve the reaction efficiency; however, excessive aeration will lead to too many bubbles in the water, reducing the contact area between the electrode and the wastewater, and accelerating the ineffective decomposition of ·OH, thereby reducing the degradation effect.

[0070] Example 10

[0071] The difference between this embodiment and the previous embodiment is that the TCPP concentration was adjusted to 200, 300, 400, and 500 mg / L, while the rest of the preparation process was the same as the previous embodiment, and TCPP degradation was carried out.

[0072] Figure 9 The graph shows the degradation effect of TCPP under different concentrations. Within the TCPP concentration range of 100–500 mg / L, the removal rate increased with increasing reaction time. Even at a high concentration of 500 mg / L, the removal rate remained around 85% after 180 min. At low concentrations, the generated ·OH molecules reacted fully with TCPP molecules; at high concentrations, the number of TCPP molecules increased, and the ·OH generation rate could not fully match the degradation requirements of the pollutants, resulting in a slight decrease in the removal rate. However, CQDs-GDE still demonstrated highly efficient degradation capabilities for high-concentration TCPP wastewater, reflecting the practical application value of the electrode.

[0073] Example 11

[0074] The difference between this embodiment and the previous embodiment is that the current density is adjusted to 5, 15, 20, and 25 mA / cm². 2 The remaining preparation processes are the same as in the examples, and TCPP degradation is carried out.

[0075] The results are as follows Figure 10 As shown, different current densities and pH values ​​have a significant impact on the degradation effect. At current densities higher than 15 mA / cm², the degradation effect is more pronounced. 2 Subsequently, the degradation effect decreased. At pH=3 and 10 mA / cm², the degradation efficiency decreased. 2 Under the specified conditions, the TCPP removal rate of CQDs-GDE can reach 91.17%. When the current density is too low, the catalytic kinetics are insufficient; when it is too high, the proportion of side reactions will increase, which will reduce the degradation efficiency.

[0076] In summary, the CQDs-GDE electrode exhibits good performance in TCPP degradation in the electro-Fenton system, especially under appropriate pH and current density conditions, and also demonstrates good cycling stability.

[0077] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a gas diffusion electrode modified with cyanobacteria carbon quantum dots, characterized in that: include, Cyanobacteria powder was uniformly dispersed in ultrapure water, and the resulting cyanobacteria dispersion was subjected to a hydrothermal reaction to synthesize pre-carbon quantum dots; after cooling, it was purified and dried to obtain cyanobacteria carbon quantum dots, denoted as BGA-CQDs. BGA-CQDs, PTFE, carbon black and anhydrous ethanol are mixed evenly to obtain an electrode slurry. The electrode slurry is coated on an electrode substrate and dried and calcined to obtain a cyanobacterial carbon quantum dot modified gas diffusion electrode, denoted as CQDs-GDE. The hydrothermal reaction temperature is 150~200℃, and the hydrothermal reaction time is 8~15h; In the electrode slurry, the mass ratio of BGA-CQDs, carbon black, and PTFE is 0.01~0.05:0.1:0.06, and the mass-volume ratio of BGA-CQDs to anhydrous ethanol is 0.01~0.05g:3mL. The electrode substrate is a pretreated carbon felt; The pretreatment involves sequentially ultrasonically cleaning with deionized water and ethanol, drying, immersing in a 2wt% polytetrafluoroethylene suspension, and then calcining.

2. The method for preparing the cyanobacterial carbon quantum dot-modified gas diffusion electrode as described in claim 1, characterized in that: The cyanobacteria powder has a particle size of 80-100 mesh; the concentration of the cyanobacteria dispersion is 10 wt.%.

3. The method for preparing the cyanobacterial carbon quantum dot-modified gas diffusion electrode as described in claim 1, characterized in that: The purification process involves first filtering the solution through a microporous membrane, then collecting the filtrate and transferring it into a dialysis bag with a molecular weight cutoff of 3500 Da, where it is dialyzed in ultrapure water for 48–72 h.

4. The method for preparing the gas diffusion electrode modified with cyanobacterial carbon quantum dots as described in claim 1, characterized in that: The calcination is carried out at a temperature of 330~380℃ for a time of 30~60min.

5. A gas diffusion electrode modified with cyanobacterial carbon quantum dots, prepared by the method described in any one of claims 1 to 4.

6. The application of a gas diffusion electrode modified with cyanobacteria carbon quantum dots as described in claim 5 in the efficient degradation of organic pollutants in an electro-Fenton system, characterized in that: include, Using an iron plate as the anode and the gas diffusion electrode as described in claim 5 as the cathode, anhydrous sodium sulfate with a concentration of 50~500mM is added as an electrolyte to wastewater containing organic pollutants, and degradation is carried out by passing electricity. The concentration of the organic pollutant is 100-500 mg / L, and the organic pollutant includes TCPP; the electrode spacing is 10 mm; during the degradation process, the aeration rate is 0-200 mL / min; and the applied current density is 5-25 mA / cm². 2 The pH range is 3 to 7.

7. The application of the cyanobacterial carbon quantum dot-modified gas diffusion electrode as described in claim 6 in the efficient degradation of organic pollutants in an electro-Fenton system, characterized in that: The CQDs-GDE has a TCPP removal rate of ≥83%; after 6 cycles, it still maintains a removal effect of over 70%.

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