A single-atom fenton bifunctional catalyst, a preparation method, an electro-oxidation system containing the bifunctional catalyst and applications

Abstract

The application discloses a single-atom Fenton bifunctional catalyst, a preparation method, an electro-oxidation system containing the bifunctional catalyst and application; the bifunctional catalyst comprises an active center and a carrier; the active center is a metal single atom; the carrier is a carbon nanotube; the metal single atom is uniformly dispersed and anchored on the surface of the carbon nanotube; the weight proportion of the metal single atom in the bifunctional catalyst is 0.3-0.4%; and the metal is one of manganese, copper, cobalt and iron. The application further discloses a preparation method of the bifunctional catalyst, an electro-oxidation system containing the bifunctional catalyst and application. Through regulation of a cathode catalyst, the application realizes in-situ generation of H2O2 and in-situ activation of H2O2 into oxygen active species such as ·OH, realizes the double function of the cathode, greatly reduces the energy consumption of electrochemical technology, improves the removal efficiency of organic matters, and efficiently degrades the organic matters while saving energy.

Description

Technical Field

[0001] This invention relates to the fields of environmental electrochemistry and advanced oxidation water treatment technology. In particular, it relates to a single-atom Fenton bifunctional catalyst, its preparation method, an electro-oxidation system comprising the bifunctional catalyst, and its applications. Background Technology

[0002] Advanced oxidation processes (AOPs) utilize technologies such as sound, light, electricity, heat, and strong oxidants. Through physicochemical means, energy is input or chemicals are added to stimulate substances in water to generate highly oxidizing hydroxyl radicals (·OH). These radicals then attack the molecular structure of recalcitrant organic matter, breaking it down into biodegradable smaller molecules, or even completely mineralizing it. AOPs mainly include ozone oxidation, ultraviolet oxidation, Fenton oxidation, and electro-oxidation, as well as their derivative and combined processes. Compared to other AOPs technologies, electro-oxidation has attracted widespread attention due to its advantages such as ease of operation, ambient temperature and pressure, no need for chemical additives, and no secondary pollution.

[0003] Traditional electro-oxidation systems primarily rely on direct and indirect oxidation processes at the anode to remove organic matter. Mainstream anodes often employ titanium-based metal oxide electrodes, such as titanium-based antimony-doped tin dioxide, titanium-based antimony-nickel-doped tin dioxide, and titanium-based lead dioxide electrodes. The anode degrades organic matter through direct oxidation or indirectly by generating Cl2, HClO, and O3. However, current cathodes mainly utilize inexpensive electrode materials like nickel foam to induce the hydrogen evolution reaction (HER), which requires a sufficiently low potential. This results in high cell voltage, high energy consumption, and the difficulty in collecting the generated hydrogen, posing safety hazards. These problems limit the widespread adoption and application of electro-oxidation technology. In recent years, researchers have addressed these issues by controlling the cathode reaction—utilizing oxygen from the air to induce an oxygen reduction reaction (ORR) on the cathode surface—instead of the traditional HER. The ORR cathode reduces energy consumption (theoretically reducing voltage by 0.6-1.2V) and allows for the selective generation of H2O2 through a two-electron reaction. The anode byproducts can further decompose H2O2 into ·OH, accelerating the degradation of organic matter.

[0004] However, through the inventors' previous research, it was found that the H2O2 generated at the cathode in the electro-oxidation system cannot be completely decomposed by the anode byproducts, resulting in a large amount of H2O2 remaining in the effluent and causing resource waste. Therefore, the inventors considered improving the cathode catalyst structure to enhance the cathode H2O2 utilization efficiency and ultimately improve the degradation capacity of organic matter. In emerging electrochemical advanced oxidation water treatment technologies such as electro-Fenton and electro-peroxidation, Fe can be added... 2+H2O2 can be activated by reagents such as O3. Related research has explored a series of issues, including improving the H2O2 yield of carbon material catalysts and efficiently utilizing H2O2 as the "core" of Fenton-like reactions.

[0005] For example, Chinese patent application number 02136606.3 discloses an invention patent entitled "Bipolar Oxidation Electrochemical Wastewater Treatment Method"; this patented technology uses gas diffusion electrodes to generate H2O2. The drawback of this technology is that the separation of the anode and cathode is not conducive to the degradation of wastewater and practical engineering applications.

[0006] For example, Chinese patent application number 200410066816.0 discloses an invention patent application entitled "A device and method for synergistic electrocatalytic treatment of organic wastewater by anode and cathode"; the technology of this patent application uses a titanium-based PbO2 anode and a carbon material cathode, with air passing through the cathode to reduce O2 to generate H2O2, while Fe is added. 2+ This process forms Fenton's reagent, enhancing the degradation of organic matter. The drawback of this technology is that it is limited by acidic pH and the amount of catalyst used, requiring the addition of large amounts of Fe. 2+ The reagents produced "iron sludge," which increased the cost of subsequent processing.

[0007] For example, Chinese patent application number 201210549472.3 uses an ozone generator to introduce a mixture of O2 and O3 into the oxygen reduction cathode. The O2 is reduced to produce H2O2, which then reacts with the introduced O3 via peroxone to produce ·OH, efficiently degrading organic matter. The drawback of this technology is that it requires exhaust gas treatment, and the ozone generator needs to provide pure oxygen and additional electrical energy.

[0008] Therefore, by regulating the cathode catalyst, H2O2 can be generated in situ and activated in situ into oxygen-active species such as ·OH. The entire process can be completed without adding any reagents to the solution, thus achieving the goal of green chemistry. Summary of the Invention

[0009] The first technical problem to be solved by the present invention is to provide a single-atom Fenton bifunctional catalyst for in-situ generation of H2O2 while activating H2O2 into oxygen-active species.

[0010] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned single-atom Fenton bifunctional catalyst.

[0011] The third technical problem to be solved by the present invention is to provide a Fenton-like coupled oxygen reduction electro-oxidation system for removing organic pollutants.

[0012] The fourth technical problem to be solved by this invention is to provide an application of a single-atom-like Fenton bifunctional catalyst.

[0013] To solve the first technical problem mentioned above, the present invention adopts the following technical solution. :

[0014] A single-atom Fenton-like bifunctional catalyst, comprising an active center and a support:

[0015] The active center is a single metal atom;

[0016] The carrier is a carbon nanotube;

[0017] The metal single atoms are uniformly dispersed and anchored on the surface of the carbon nanotubes.

[0018] The metal single atom accounts for 0.3-0.4% of the weight of the duplex catalyst;

[0019] The metal is one of manganese, copper, cobalt, and iron.

[0020] To solve the second technical problem mentioned above, the present invention adopts the following technical solution. :

[0021] A method for preparing the above-mentioned single-atom Fenton bifunctional catalyst includes the following steps:

[0022] 1) Carboxylated carbon nanotubes were pretreated in concentrated hydrochloric acid and stirred to wash away impurity metal ions on the surface of the carbon nanotubes; then they were filtered, washed with ultrapure water and dried in an oven to obtain pretreated carboxylated carbon nanotubes for later use.

[0023] 2) Disperse the metal phthalocyanine and pretreated carboxylated carbon nanotubes separately in DMF solvent, and sonicate and stir until they are evenly dispersed; then, mix the two dispersions, stir at room temperature to make them evenly dispersed, then filter the mixture, wash with ultrapure water, and then dry in an oven to obtain the metal phthalocyanine-carbon nanotube composite precursor, grind it into powder, and set aside for later use.

[0024] 3) The metal phthalocyanine-carbon nanotube composite precursor powder obtained by grinding was loaded into a ceramic boat and placed in a tube furnace. N2 was bubbled in at room temperature to purge the O2 inside the tube. Then, the metal phthalocyanine-carbon nanotube composite precursor powder was pyrolyzed at the annealing temperature under the protection of N2 atmosphere. The programmed heating rate and annealing rate were both set to 4-6℃ / min. -1 A series of powder samples were obtained after high-temperature pyrolysis treatment, and then ground into powder for later use.

[0025] 4) Place the powder sample obtained in step 3) in H2SO4 solution for post-processing; stir at constant temperature, then filter, wash with ultrapure water, and dry in an oven to obtain a single-atom Fenton bifunctional catalyst.

[0026] Preferably, in step 1), the ratio of concentrated hydrochloric acid to carboxylated carbon nanotubes is 18-22 mL / 190-210 mg.

[0027] Preferably, in step 1), the carboxylated carbon nanotubes have a purity > 95%, a diameter of 10-20 nm, and a length of 10-30 μm.

[0028] Preferably, in step 1), the stirring time is 5-7 hours.

[0029] Preferably, in step 1), the drying temperature of the oven is 60-80℃.

[0030] Preferably, in step 2), the mass ratio of the metal phthalocyanine to the pretreated carboxylated carbon nanotubes is 380-420:190-210.

[0031] Preferably, in step 2), the stirring time at room temperature is 10-14 hours.

[0032] Preferably, in step 2), the drying temperature of the oven is 60-80℃.

[0033] Preferably, in step 3), the annealing temperature is 600-900℃, including 600℃, 700℃, 800℃ and 900℃.

[0034] Preferably, in step 3), the pyrolysis time is 3-5 hours.

[0035] Preferably, in step 3), the temperature of the high-temperature pyrolysis is 650-750℃.

[0036] Preferably, in step 4), the concentration of H2SO4 is 0.4-0.6 mol / L. -1 .

[0037] Preferably, in step 4), the temperature of the constant-temperature stirring is 65-75℃.

[0038] Preferably, in step 4), the drying temperature of the oven is 60-80℃.

[0039] To solve the third technical problem mentioned above, the present invention adopts the following technical solution. :

[0040] A Fenton-like coupled oxygen reduction electro-oxidation system for decomposing organic pollutants, comprising a cathode and an anode;

[0041] The cathode is a gas diffusion electrode;

[0042] The anode is a titanium-based metal oxide electrode;

[0043] The gas diffusion electrode is constructed by coating and drying a single-atom Fenton bifunctional catalyst onto a carbon film, with a graphite plate as the support.

[0044] To solve the fourth technical problem mentioned above, the present invention adopts the following technical solution. :

[0045] An electrochemical water treatment method for degrading organic matter using a Fenton-like coupled oxygen reduction electrooxidation method includes the following conditions:

[0046] A titanium-based metal oxide anode and a gas diffusion cathode formed by a single-atom Fenton-like bifunctional catalyst are arranged in parallel in a diaphragm-free electrolytic cell containing wastewater. A DC constant voltage power supply provides 3–5V and 5–20mA / cm². 2 Current density, air is introduced on the cathode side, and the air flow rate is not less than 5 mL / min / cm. 2 .

[0047] This invention can significantly reduce the energy consumption of electrochemical technology and improve the removal efficiency of organic matter.

[0048] Preferably, the specific steps for forming a gas diffusion cathode using a single-atom Fenton bifunctional catalyst are as follows: dissolve the single-atom Fenton bifunctional catalyst and a 4-6% Nafion solution in anhydrous ethanol at a mass ratio of 1:5, mix them uniformly by ultrasonication, then repeatedly coat the mixture onto a carbon film and dry it under infrared lamp irradiation, with a coating area of ​​22-28 cm². 2 An air diffusion electrode is prepared by attaching the coated carbon film onto a graphite plate.

[0049] The present invention has the following beneficial effects :

[0050] This invention achieves in-situ generation of H2O2 and in-situ activation of H2O2 into oxygen-active species such as ·OH by regulating the cathode catalyst. The entire process can activate H2O2 without adding any reagents to the solution, thus achieving the goal of green chemistry. While realizing the dual function of the cathode, it greatly reduces the energy consumption of electrochemical technology, improves the removal efficiency of organic matter, and achieves efficient degradation of organic matter while being more energy-efficient.

[0051] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0052] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0053] Figure 1 These are morphological images of the present invention under transmission electron microscopy and spherical aberration electron microscopy.

[0054] Figure 2This is a graph showing the electrochemical activity of the present invention.

[0055] Figure 3 This is a comparison chart of the phenol removal rates of the present invention;

[0056] Figure 4 This invention provides a free radical detection signal during the degradation process.

[0057] Figure 5 This is a comparison chart showing the TOC removal rate of landfill leachate according to the present invention;

[0058] Figure 6 This is a schematic diagram of the single-atom-like Fenton-coupled oxygen reduction electro-oxidation system of the present invention. Detailed Implementation

[0059] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0060] As one aspect of the present invention, the present invention provides a single-atom Fenton-like bifunctional catalyst, the bifunctional catalyst comprising an active center and a support:

[0061] The active center is a single metal atom;

[0062] The carrier is a carbon nanotube;

[0063] The metal single atoms are uniformly dispersed and anchored on the surface of carbon nanotubes by in-situ pyrolysis.

[0064] The metal single atom accounts for 0.3-0.4% of the weight of the duplex catalyst;

[0065] The metal is one of manganese, copper, cobalt, and iron.

[0066] The single-atom Fenton bifunctional catalyst of this invention improves the utilization rate of metal atoms, increases the number of reactive sites, enhances electrocatalytic activity, and promotes the decomposition of H2O2 to produce ·OH by controlling the size of the metal to the atomic level. Secondly, it uses carbon nanotubes with good conductivity, large specific surface area, and high two-electron activity as the single-atom anchoring support, and uses transition metals with multiple oxidation states that can be regenerated through redox reactions and can react with H2O2 to generate ·OH as the metal single atoms.

[0067] See Figure 1As shown, the presence of single atoms was observed from the perspective of morphology using TEM and HAADF-STEM. No nanoparticles or agglomeration were observed in the field of view. The presence of single atoms and their coordination environment were confirmed from the perspective of atomic coordination environment using synchrotron radiation technology.

[0068] In another aspect, the present invention provides a method for preparing the above-mentioned single-atom Fenton bifunctional catalyst, comprising the following steps:

[0069] 1) Carboxylated carbon nanotubes were pretreated in concentrated hydrochloric acid and stirred to wash away impurity metal ions on the surface of the carbon nanotubes; then they were filtered, washed with ultrapure water and dried in an oven to obtain pretreated carboxylated carbon nanotubes for later use.

[0070] 2) The metal phthalocyanine and pretreated carboxylated carbon nanotubes were dispersed separately in DMF solvent, and ultrasonicated and stirred until they were uniformly dispersed. Then, the two dispersions were mixed and stirred at room temperature to make them uniformly dispersed. The mixture was then filtered, washed with ultrapure water, and dried in an oven to obtain the metal phthalocyanine-carbon nanotube composite precursor, which was then ground into powder for later use. N,N-dimethylformamide was selected as the solvent, which not only ensured good dispersibility of carbon materials in the solvent, but also provided high solubility of metal phthalocyanine in the solvent.

[0071] 3) The metal phthalocyanine-carbon nanotube composite precursor powder obtained by grinding was loaded into a ceramic boat and placed in a tube furnace. N2 was bubbled in at room temperature to purge the O2 inside the tube. Then, the metal phthalocyanine-carbon nanotube composite precursor powder was pyrolyzed at the annealing temperature under the protection of N2 atmosphere. The programmed heating rate and annealing rate were both set to 4-6℃ / min. -1 A series of powder samples were obtained after high-temperature pyrolysis treatment, and then ground into powder for later use.

[0072] 4) Place the powder sample obtained in step 3) in H2SO4 solution for post-processing; stir at constant temperature, then filter, wash with ultrapure water, and dry in an oven to obtain a single-atom Fenton bifunctional catalyst.

[0073] In some embodiments of the present invention, in step 1), the ratio of concentrated hydrochloric acid to carboxylated carbon nanotubes is 18-22 mL / 190-210 mg.

[0074] In some embodiments of the present invention, in step 1), the carboxylated carbon nanotubes have a purity > 95%, a diameter of 10-20 nm, and a length of 10-30 μm.

[0075] In some embodiments of the present invention, in step 1), the stirring time is 5-7 hours.

[0076] In some embodiments of the present invention, in step 1), the drying temperature of the oven is 60-80°C.

[0077] In some embodiments of the present invention, in step 2), the mass ratio of the metal phthalocyanine to the pretreated carboxylated carbon nanotubes is 380-420:190-210. This range is the optimal range for the adsorption of metal phthalocyanine onto carbon nanotubes. If it is not within this range, the adsorption amount of metal phthalocyanine will be insufficient or excessive, resulting in insufficient catalytic performance or waste of resources.

[0078] In some embodiments of the present invention, in step 2), the stirring time at room temperature is 10-14 hours.

[0079] In some embodiments of the present invention, in step 2), the drying temperature of the oven is 60-80°C.

[0080] In some embodiments of the present invention, in step 3), the annealing temperature is 600-900°C, including 600°C, 700°C, 800°C, and 900°C.

[0081] In some embodiments of the present invention, in step 3), the pyrolysis time is 3-5 hours.

[0082] In some embodiments of the present invention, in step 3), the temperature of the high-temperature pyrolysis is 650-750°C.

[0083] In some embodiments of the present invention, in step 4), the concentration of H2SO4 is 0.4-0.6 mol / L. -1 .

[0084] In some embodiments of the present invention, in step 4), the temperature of the constant temperature stirring is 65-75°C.

[0085] In some embodiments of the present invention, in step 4), the drying temperature of the oven is 60-80°C.

[0086] As another aspect of the present invention, the present invention provides a Fenton-like coupled oxygen reduction electro-oxidation system for decomposing organic pollutants, comprising a cathode and an anode;

[0087] The cathode is a gas diffusion electrode;

[0088] The anode is a titanium-based metal oxide electrode;

[0089] The gas diffusion electrode is constructed by coating and drying a single-atom Fenton bifunctional catalyst onto a carbon film, with a graphite plate as the support.

[0090] As another aspect of the present invention, the present invention provides an electrochemical water treatment method for the degradation of organic matter by Fenton-like coupled oxygen reduction electrooxidation, comprising the following conditions:

[0091] A titanium-based metal oxide anode and a gas diffusion cathode formed by a single-atom Fenton-like bifunctional catalyst are arranged in parallel in a diaphragm-free electrolytic cell containing wastewater. A DC constant voltage power supply provides 3–5V and 5–20mA / cm². 2 Current density, air is introduced on the cathode side, and the air flow rate is not less than 5 mL / min / cm. 2 .

[0092] This invention can significantly reduce the energy consumption of electrochemical technology and improve the removal efficiency of organic matter.

[0093] Preferably, the specific steps for forming a gas diffusion cathode using a single-atom Fenton bifunctional catalyst are as follows: dissolve the single-atom Fenton bifunctional catalyst and a 4-6% Nafion solution in anhydrous ethanol at a mass ratio of 1:5, mix them uniformly by ultrasonication, then repeatedly coat the mixture onto a carbon film and dry it under infrared lamp irradiation, with a coating area of ​​22-28 cm². 2 An air diffusion electrode is prepared by attaching the coated carbon film onto a graphite plate.

[0094] Example 1

[0095] A method for preparing the above-mentioned single-atom Fenton bifunctional catalyst includes the following steps:

[0096] 1) Pretreatment: 200 mg of carboxylated carbon nanotubes (the purity of the carboxylated carbon nanotubes is >95%, the diameter is 15 nm, and the length is 20 μm) were placed in 20 mL of concentrated hydrochloric acid and stirred for 6 h to wash away the impurity metal ions on the surface of the carbon nanotubes; then the mixture was filtered, washed with ultrapure water, and dried in an oven at 70 °C to obtain pretreated carboxylated carbon nanotubes for later use.

[0097] 2) 400 mg of metal phthalocyanine and 200 mg of pretreated carboxylated carbon nanotubes were dispersed in DMF solvent, and ultrasonicated and stirred until they were evenly dispersed. Then, the two dispersions were mixed and stirred at room temperature for 12 h to make them evenly dispersed. The mixture was then filtered, washed with ultrapure water, and dried in an oven at 70 °C to obtain the metal phthalocyanine-carbon nanotube composite precursor, which was then ground into powder for later use.

[0098] 3) The metal phthalocyanine-carbon nanotube composite precursor powder obtained by grinding was loaded into a ceramic boat and placed in a tube furnace. N2 was bubbled in at room temperature to purge the O2 in the tube (about 25-35 min). Then, under the protection of N2 atmosphere, the metal phthalocyanine-carbon nanotube composite precursor powder was pyrolyzed at an annealing temperature of 700℃ for 4 hours, with the programmed heating rate and annealing rate both set to 5℃ / min. -1 A series of powder samples were obtained after high-temperature pyrolysis at 700℃, and then ground into powder for later use.

[0099] 4) Place the powder sample obtained in step 3) in a 0.5 mol L... -1 The sample was post-treated in H2SO4 solution; stirred at 70℃, then filtered, washed with ultrapure water, and dried in a 70℃ oven to obtain the single-atom Fenton bifunctional catalyst 700-SAC.

[0100] The preparation method in this embodiment is a catalyst preparation method, and the catalyst is named 700-SAC. The catalyst preparation ink is coated onto a carbon film to form an air diffusion electrode, which is named 700-SAC-GDE. The catalyst is used in the performance tests. Air diffusion electrodes are used in all degradation experiments.

[0101] Figure 1 These are TEM and HAADF-STEM images of the single-atom Fenton-like bifunctional catalyst prepared in this embodiment.

[0102] Example 2

[0103] Example 1 was repeated, except that in step 3), the annealing temperature was 600°C. A single-atom Fenton bifunctional catalyst, 600-SAC, was obtained.

[0104] Example 3

[0105] Example 1 was repeated, except that in step 3), the annealing temperature was 800°C. A single-atom Fenton bifunctional catalyst, 800-SAC, was obtained.

[0106] Example 4

[0107] Example 1 was repeated, except that in step 3), the annealing temperature was 900°C. A single-atom Fenton bifunctional catalyst, 900-SAC, was obtained.

[0108] Example 5

[0109] The electrochemical activity of single-atom catalysts at different pyrolysis temperatures was tested using an electrochemical workstation, and the results are as follows:

[0110] like Figure 2 As shown, CV was used to detect electrochemical double-layer capacitance and ORR activity.

[0111] The single-atom Fenton bifunctional catalyst obtained at a pyrolysis temperature of 700°C in Example 1 has the largest double-layer capacitance, the largest electrochemical active surface area, and more catalytic active sites, which is beneficial for activating H2O2 to generate ·OH.

[0112] After the introduction of O2, all the single-atom catalysts showed obvious reduction peaks in the O2 saturated electrolyte, indicating that ORR occurred on the single-atom catalysts.

[0113] Rotating ring disk electrode assays were used to evaluate the selectivity of the two-electron pathway in the ORR reaction of the catalyst.

[0114] Among them, the single-atom Fenton bifunctional catalyst obtained at a pyrolysis temperature of 700°C in Example 1 can detect a high ring current, and the corresponding H2O2 selectivity is about 60%.

[0115] Based on the above experimental results, it can be inferred that 700-SAC has a larger specific surface area and a higher electrochemically active surface area. Therefore, it can provide more active sites for 2e-ORR on the electrode, thereby improving the H2O2 yield of the electrode. LSV testing was used to detect this; after adding H2O2, the single-atom catalyst with a pyrolysis temperature of 700℃ exhibited a higher H2O2 reduction current, indicating better activation performance for the production of ·OH from H2O2.

[0116] Example 6

[0117] The degradation performance of phenol was studied using gas diffusion electrodes prepared with single-atom catalysts at different pyrolysis temperatures as cathodes and ruthenium-iridium-titanium (Ti / Ir-RuO2) as anodes.

[0118] The anode and cathode are arranged in parallel in a diaphragm-free electrolytic cell, each with an effective area of ​​5×5cm. 2 With a plate spacing of 1 cm, the treatment of 200 mg / L phenol wastewater was carried out using 0.1 M Na₂SO₄ as the electrolyte and a current density of 10 mA / cm². 2 Charging. Air is introduced into the cathode side at a flow rate of not less than 5 mL / min / cm. 2 .

[0119] like Figure 3 As shown, the single-atom gas diffusion cathode with a pyrolysis temperature of 700℃ can achieve 100% phenol degradation within 7 hours, exhibiting the highest degradation rate. The ORR mode catalytic effect after synergistic Fenton reaction is significantly stronger than the other two cathodes, and the energy consumption of 700-SAC-GDE (product obtained in Example 1) is greatly reduced compared to the HER and ORR modes.

[0120] like Figure 4 As shown, electron paramagnetic resonance (EPR) technology was used to detect free radicals during the degradation process. The 700-SAC electrode mainly exhibited ·OH radicals during degradation. 1 O2 (singlet oxygen) and ·O2 - These are oxygen-active substances, with ·OH being the dominant component. They primarily utilize ·OH to attack and remove organic matter.

[0121] Furthermore, DFT calculations revealed that the metal sites can adsorb the target pollutants while simultaneously decomposing the in-situ generated H₂O₂ into ·OH. This research provides a new approach for the safe and efficient treatment of high-concentration pollutants in organic wastewater.

[0122] Example 7

[0123] like Figure 6 As shown, a Fenton-like coupled oxygen reduction electro-oxidation system was constructed using a single-atom gas diffusion cathode with a pyrolysis temperature of 700℃ and a titanium-based transition metal-doped tin dioxide anode. The treatment effect of this system on landfill leachate biochemical effluent was studied.

[0124] like Figure 5 As shown, the study on TOC removal rate reveals that the ORR-EO system after synergistic Fenton reaction has increased the TOC removal rate of landfill leachate biochemical effluent by 20% compared to the original ORR-EO system, achieving a further improvement in the degradation of recalcitrant organic wastewater.

[0125] Comparative Example 1

[0126] Example 6 is repeated, except that a nickel foam electrode is used as the cathode.

[0127] The results showed that the comparative Fenton reaction system achieved a phenol removal rate of only about 10%, and its energy consumption was higher than that of the ORR mode. Therefore, the HER mode has a negligible effect on the removal of organic matter.

[0128] Comparative Example 2

[0129] Example 6 was repeated, except that a multi-walled carbon nanotube catalyst gas diffusion electrode was used as the cathode.

[0130] The results showed that the phenol removal rate of the comparative Fenton reaction system was about 40%. This indicates that the synergistic effect of H2O2 generated at the cathode and the anolyte on the degradation of organic matter has a certain effect. However, the low utilization rate of H2O2 means that the ability to remove organic matter needs to be improved.

[0131] Comparative Example 3

[0132] Repeat the remaining experimental conditions of Example 6, except that: CNT powder and metal oxide nanoparticles were mixed uniformly in a 1:1 ratio to obtain a nanoscale-based Fenton-like bifunctional catalyst, which was then used as an air diffusion electrode as a cathode.

[0133] The results showed that the comparative Fenton reaction system achieved a phenol removal rate of 60% and had lower energy consumption compared to the ORR mode. This indicates that the Fenton-like bifunctional catalyst can improve the H2O2 activation efficiency. However, due to the low number of active sites exposed by the nanoparticles, the organic matter removal effect still needs to be improved.

[0134] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A Fenton-like coupled oxygen reduction electro-oxidation method for the degradation of organic matter by electrochemical water treatment, characterized in that, Including the following conditions: A titanium-based metal oxide anode and a gas diffusion cathode formed by a single-atom Fenton-like bifunctional catalyst are arranged in parallel in a diaphragm-free electrolytic cell containing wastewater. A DC constant voltage power supply provides 3~5V and 5~20mA / cm². 2 Current density, air is introduced on the cathode side, and the air flow rate is not less than 5 mL / min / cm. 2 ; The single-atom Fenton bifunctional catalyst comprises an active center and a support; the active center is a metal single atom; the support is a carbon nanotube; the metal single atom is uniformly dispersed and anchored on the surface of the carbon nanotube; the weight percentage of the metal single atom in the bifunctional catalyst is 0.3-0.4%; the metal is manganese.

2. The processing method according to claim 1, characterized in that: The specific steps for forming a gas diffusion cathode using a single-atom Fenton bifunctional catalyst are as follows: Dissolve the single-atom Fenton bifunctional catalyst (mass ratio 1:5) in anhydrous ethanol with a 4-6% Nafion solution, ultrasonically mix thoroughly, then repeatedly coat the mixture onto a carbon film and dry it under infrared light. The coating area is 22-28 cm². 2 An air diffusion electrode is prepared by attaching the coated carbon film onto a graphite plate.

3. A Fenton-like coupled oxygen reduction electro-oxidation system for decomposing organic pollutants, comprising a cathode and an anode; characterized in that: The cathode is a gas diffusion electrode; The anode is a titanium-based metal oxide electrode; The gas diffusion electrode is the gas diffusion electrode as described in claim 2.

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