Electrode material based on non-heme iron catalyst and preparation method and application thereof

Abstract

The application discloses an electrode material based on a non-haem iron catalyst and a preparation method and application thereof, and belongs to the field of electrocatalytic water treatment. The electrode material is used as a substrate, and an auxiliary ligand polymer layer and a non-haem iron catalyst layer are sequentially deposited on the substrate; the auxiliary ligand polymer layer is polymerized from organic monomers; the non-haem iron catalyst layer is formed by reaction of a ferrous salt and dopamine to form a precursor and then electrochemical polymerization; and the auxiliary ligand polymer layer and the non-haem iron catalyst layer are connected through coordination bonds. The auxiliary ligand polymer layer and the non-haem iron catalyst are electrochemically polymerized on the electrode material, so that the selectivity of the electrode material for electrocatalytic oxygen two-electron reduction to produce hydrogen peroxide is improved, and the hydrogen peroxide yield is increased. In addition, the non-haem iron catalyst can further produce superoxide free radicals through regulation of single-electron reduction of oxygen, promote the generation of hydroxyl free radicals from hydrogen peroxide, and maintain good electrocatalytic removal efficiency of organic pollutants under near-neutral conditions.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic water treatment, specifically to an electrode material based on a non-heme iron catalyst, its preparation method, and its application. Background Technology

[0002] Conventional wastewater treatment processes are ineffective at removing recalcitrant and high-risk organic pollutants from wastewater, and the release of these pollutants into the environment poses significant health risks. Electrocatalysis technology can directly oxidize pollutants by relying on the strong electron-withdrawing ability of the anode, or indirectly oxidize pollutants by relying on the negative potential of the cathode to generate reactive oxygen species (such as hydroxyl radicals) through the reduction of oxygen. Electrocatalysis based on direct anode oxidation is affected by electrode fouling, while electrocatalysis based on indirect cathode oxidation has attracted widespread attention due to its high oxidative activity.

[0003] The electrocatalytic reduction of oxygen occurs via two main pathways: four-electron reduction to water and two-electron reduction to hydrogen peroxide. The significant thermodynamic advantage of four-electron reduction leads to low hydrogen peroxide yields. On the other hand, hydrogen peroxide, due to its low oxidizing power, is difficult to directly remove pollutants. Fenton and Fenton-like catalysts can activate hydrogen peroxide to generate reactive oxygen species such as hydroxyl radicals or singlet oxygen; however, the activity of most catalysts is pH-limited, maintaining high activity only under acidic conditions, which greatly restricts the application of electrocatalytic oxygen activation technology.

[0004] Existing electro-Fenton technology generates hydrogen peroxide by reducing oxygen at the cathode, followed by the external addition of Fe. 2+ The cathode reacts with in-situ generated hydrogen peroxide via a Fenton reaction, producing highly oxidizing hydroxyl radicals, thereby achieving efficient removal of organic pollutants. In this technology, the cathode can not only reduce oxygen to produce hydrogen peroxide, but also reduce Fe. 3+ Fe 2+ This aims to accelerate the Fenton reaction. However, in the electro-Fenton technique, due to the thermodynamic advantage of the oxygen four-electron reaction, the yield of hydrogen peroxide is low. Furthermore, the activity of the Fenton reaction decreases sharply at pH levels above 3, and it produces iron sludge, causing secondary pollution. Summary of the Invention

[0005] Objectives of the Invention: The first objective of this invention is to provide an electrode material based on a non-heme iron catalyst with excellent electrocatalytic performance and wide pH adaptability. The second objective of this invention is to provide a method for preparing the above-mentioned electrode material based on a non-heme iron catalyst. The third objective of this invention is to provide applications of the above-mentioned electrode material based on a non-heme iron catalyst.

[0006] Technical solution: The electrode material based on non-heme iron catalyst provided by the present invention uses the electrode material as a substrate, on which an auxiliary ligand polymerization layer and a non-heme iron catalyst layer are sequentially deposited. The auxiliary ligand polymerization layer is polymerized from organic monomers, and the non-heme iron catalyst layer is obtained by electrochemical polymerization of a precursor formed by the reaction of ferrous salt and dopamine. The auxiliary ligand polymerization layer and the non-heme iron catalyst layer are connected by coordination bonds.

[0007] Furthermore, the organic monomer is a polymerizable organic monomer having a thiophene ring, a furan ring, or a pyrrole ring, such as thiophene, furan, pyrrole, 2-nitrothiophene, (S)-N,N-dimethyl-3-hydroxy-3-(2-thiophene)propylamine, N-methyl-2-thiophene methylamine, or 2-thiophene methylamine, etc.

[0008] Furthermore, in the non-heme iron catalyst layer, the molar ratio of ferrous salt to dopamine is 0.14:1-2:1, preferably 0.14:1-1:1.

[0009] Furthermore, the electrode material is graphite.

[0010] In this invention, the catalytic performance of the non-heme iron catalyst is based on iron as the active center. However, due to the strong interaction between the iron center and oxygen, the resulting iron-oxygen hybrid species often selectively break the O-O bond, inhibiting the generation of superoxide radicals. Meanwhile, the nitrogen, oxygen, or sulfur functional groups in the pyrrole, furan, or thiophene rings of the auxiliary ligand polymerization layer can form coordination bonds with the iron center, increasing the electron cloud density of the iron center, weakening the stability of the Fe-O bond, thereby preserving the O-O bond and promoting the generation of superoxide radicals.

[0011] This invention provides a method for preparing the above-mentioned electrode material based on a non-heme iron catalyst, comprising the following steps:

[0012] (1) The organic monomer is fully dissolved in an organic solvent, and after deoxygenation treatment, it is electropolymerized in a three-electrode system by cyclic voltammetry or constant potential polymerization to electropolymerize the organic monomer onto the surface of the electrode material, thereby obtaining an electrode material with an auxiliary ligand polymerization layer.

[0013] (2) Dissolve dopamine hydrochloride in a solvent, remove oxygen, add ferrous salt, stir thoroughly, and prepare a non-heme iron catalyst precursor solution.

[0014] (3) Using a non-heme iron catalyst precursor solution as an electrolyte and an electrode material with an auxiliary ligand polymerization layer as a working electrode, electropolymerization is carried out in a three-electrode system by cyclic voltammetry to electropolymerize the non-heme iron catalyst onto the surface of the electrode material with the auxiliary ligand polymerization layer. After electropolymerization, the electrode material is fully soaked to obtain an electrode material based on the non-heme iron catalyst.

[0015] Furthermore, in steps (1) and (2), the process parameters for the deoxygenation treatment are: nitrogen aeration for 10-20 min, and nitrogen flow rate per liter of solution is 1-10 mL / min.

[0016] Further, in step (1), the molar concentration of the organic monomer in the organic solvent is 1-20 mM, preferably 5-10 mM; the organic solvent is acetonitrile containing 10-500 mM tetrabutylperchlorate or phosphate buffer with a molar concentration of 20-100 mM.

[0017] Further, in step (2), the molar concentration of dopamine hydrochloride in the solvent is 5-10 mM; the ferrous salt is ferrous chloride; and the solvent is a phosphate buffer with a molar concentration of 20-100 mM.

[0018] Further, in steps (1) and (3), the process parameters for the cyclic voltammetric electropolymerization are: low voltage setting range of -0.8 to -0.2V, high voltage setting range of 0.6 to 1.0V, cyclic scanning of 10-100 cycles, and scanning speed range of 10-100mV / s; in step (1), the electropolymerization process parameters for the constant potential polymerization method are: weighing 1-20mM of auxiliary ligand monomer and dissolving it in acetonitrile, using 10-500mM tetrabutylammonium perchlorate as the electrolyte, using a glassy carbon electrode as the working electrode, and selecting Ag / Ag as the reference electrode. + The electrode and the counter electrode are platinum wires. The polymerization potential is determined by differential pulse voltammetry. The scanning range is 0-3V. The potential at which the oxidation peak appears is the polymerization potential of the auxiliary ligand monomer. The obtained polymerization potential is the potential applied during constant potential polymerization. The time is set to 5min-1h. In step (3), the soaking parameters are 5-30h.

[0019] This invention provides the application of the above-mentioned electrode material based on non-heme iron catalyst in the field of electro-Fenton degradation of pollutants.

[0020] Furthermore, the application method is as follows: using an electrode material based on a non-heme iron catalyst as the working electrode, and using water containing pollutants as the electrolyte, an electrocatalytic degradation reaction is carried out in a three-electrode system.

[0021] Furthermore, the pH range of the water containing pollutants is 2-6; the counter electrode in the three-electrode system is a platinum sheet, the reference electrode is Ag / AgCl, and the spacing between each electrode is 2-3 cm; the process parameters of the electrocatalytic degradation reaction are: a controlled temperature of 30-35℃, a stirring speed of 500-1000 rpm, an oxygen aeration flow rate of 20-25 mL / min, and a constant potential applied to the working electrode through an electrochemical workstation, with the voltage set from -0.5V to -1.5V.

[0022] Furthermore, the pollutant is bisphenol A, with a concentration of 5-500 mg / L in the water.

[0023] Invention Principle: This invention improves the selectivity of the two-electron reduction of oxygen to hydrogen peroxide by electropolymerizing an auxiliary ligand polymerization layer on the electrode material and a non-heme iron catalyst, thereby increasing the yield of hydrogen peroxide. Furthermore, the non-heme iron catalyst can further promote the generation of superoxide radicals by regulating the single-electron reduction of oxygen, thereby promoting the generation of hydroxyl radicals from hydrogen peroxide, and maintaining good efficiency in the electrocatalytic removal of organic pollutants under near-neutral conditions.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) Experimental results show that, compared with the blank graphite electrode, the cumulative concentration of hydrogen peroxide generated by the electrode material based on the non-heme iron catalyst of the present invention is significantly improved. After 1.5 h, the hydrogen peroxide generated by the blank graphite electrode is 4.9 mg / L, and the hydrogen peroxide generated by the non-heme iron catalyst is 15.8 mg / L, which is 222.4% higher than that of the blank graphite electrode; (2) Compared with the blank graphite electrode, the electrocatalytic removal rate of bisphenol A by the electrode material based on the non-heme iron catalyst of the present invention is significantly improved. Among the non-heme iron catalysts, the removal rate of bisphenol A reaches a maximum of 3.24 h. -1 While blank graphite only has 0.20h. -1 (3) Compared with conventional electro-Fenton technology, which can only maintain a good effect under pH < 3 conditions, the electrode material of the present invention based on non-heme iron catalyst still maintains a high bisphenol A removal rate under pH < 6 conditions; (4) The electrode material of the present invention based on non-heme iron catalyst still maintains good BPA removal performance under a low potential (-0.5V). Attached Figure Description

[0025] Figure 1 This is a diagram illustrating the reaction mechanism between non-heme iron catalysts and auxiliary ligands with H2O2.

[0026] Figure 2 XPS full scan images of the electrode materials in Comparative Examples 1-3 and the non-heme iron catalyst electrode in Example 1.

[0027] Figure 3 The concentration diagram shows the concentration of hydrogen peroxide generated by the electrode materials in Comparative Examples 1-3 and the non-heme iron catalyst electrode in Example 1.

[0028] Figure 4 Electron spin resonance spectra of the electrode materials in Comparative Examples 1-3 and the non-heme iron catalyst electrode in Example 1 for electrocatalysis of superoxide radicals.

[0029] Figure 5 The graph shows the rate of bisphenol A removal by the electrode materials in Comparative Examples 1-3 and the non-heme iron catalyst electrode in Example 1.

[0030] Figure 6 Rates of bisphenol A removal by non-heme iron catalysts prepared for different molar ratios of ferrous chloride and dopamine;

[0031] Figure 7 The rate of bisphenol A removal by non-heme iron catalyst electrode at different pH values ​​is shown in the graph.

[0032] Figure 8 The rate of bisphenol A removal by non-heme iron catalyst electrode at different voltages is shown in the graph.

[0033] Figure 9 This is a graph showing the rate of bisphenol A removal by non-heme iron catalyst electrodes based on different auxiliary ligands. Detailed Implementation

[0034] The present invention will now be further described in conjunction with specific embodiments and accompanying drawings.

[0035] Example 1: The electrode material based on a non-heme iron catalyst provided in this example uses graphite as a substrate, on which a polypyrrole layer and a non-heme iron catalyst layer are sequentially deposited. The non-heme iron catalyst layer is obtained by reacting ferrous salt and dopamine, with a molar ratio of ferrous salt to dopamine of 0.2:1.

[0036] The preparation steps of the above electrode material are as follows:

[0037] (1) Preparation of graphite-polypyrrole electrode material: Weigh 5 mM of pyrrole monomer, dissolve it in 20 mM phosphate buffer, and aerate with nitrogen for 10 min at a flow rate of 100 mL / min. Electropolymerization was performed using a three-electrode system, with a platinum sheet (10×10×0.1 mm) as the counter electrode, Ag / AgCl as the reference electrode, and a cleaned graphite sheet (40×25×2 mm) as the working electrode. Electropolymerization was carried out by cyclic voltammetry, with a low voltage set at -0.5 V, a high voltage range set at 0.8 V, a voltage scan of 50 cycles, and a scan rate range of 20 mV / s. After the reaction, the material was thoroughly washed with ultrapure water to obtain the graphite-polypyrrole electrode material.

[0038] (2) Preparation of non-heme iron catalyst precursor solution: Weigh 5 mM dopamine hydrochloride and dissolve it in 20 mM PBS solution, add 1 mM FeCl2, aerate with nitrogen for 10 min at a flow rate of 100 mL / min, stir thoroughly so that ferrous ions and dopamine are linked through Fe-O bonds to form non-heme iron catalyst monomer, and obtain non-heme iron catalyst precursor solution;

[0039] (3) Preparation of electrode material based on non-heme iron catalyst: The non-heme iron catalyst precursor solution in step (2) is used as the electrolyte, and electropolymerization is carried out in a three-electrode system. The counter electrode is a platinum sheet (10×10×0.1mm), the reference electrode is Ag / AgCl, and the working electrode is the graphite-polypyrrole electrode synthesized in step (1). Electropolymerization is carried out by cyclic voltammetry. The low voltage is set to -0.5V, the high voltage range is set to 0.8V, the cyclic scan is 50 times, the scan speed range is 20mV / s, and after the reaction is completed, it is soaked for 10 hours. After the reaction is completed, it is thoroughly washed with ultrapure water to obtain the electrode material based on non-heme iron catalyst.

[0040] Example 2: The electrode material based on a non-heme iron catalyst provided in this example uses graphite as a substrate, on which a polypyrrole layer and a non-heme iron catalyst layer are sequentially deposited. The non-heme iron catalyst layer is obtained by reacting ferrous salt and dopamine, with a molar ratio of ferrous salt to dopamine of 0.5:1.

[0041] The preparation steps of the above electrode material are as follows:

[0042] (1) Preparation of graphite-polypyrrole electrode material: Weigh 5 mM of pyrrole monomer, dissolve it in 20 mM phosphate buffer, and aerate with nitrogen for 10 min at a flow rate of 100 mL / min. Electropolymerization was performed using a three-electrode system, with a platinum sheet (10×10×0.1 mm) as the counter electrode, Ag / AgCl as the reference electrode, and a cleaned graphite sheet (40×25×2 mm) as the working electrode. Electropolymerization was carried out by cyclic voltammetry, with a low voltage set at -0.5 V, a high voltage range set at 1.0 V, a voltage scan of 50 cycles, and a scan rate range of 20 mV / s. After the reaction, the material was thoroughly washed with ultrapure water to obtain the graphite-polypyrrole electrode material.

[0043] (2) Preparation of non-heme iron catalyst precursor solution: Weigh 10 mM dopamine hydrochloride and dissolve it in 20 mM PBS solution, add 5 mM FeCl2, aerate with nitrogen for 10 min at a nitrogen flow rate of 100 mL / min, stir thoroughly so that ferrous ions and dopamine are linked through Fe-O bonds to form non-heme iron catalyst monomer, and obtain non-heme iron catalyst precursor solution;

[0044] (3) Preparation of electrode material based on non-heme iron catalyst: The non-heme iron catalyst precursor solution in step (2) is used as the electrolyte, and electropolymerization is carried out in a three-electrode system. The counter electrode is a platinum sheet (10×10×0.1mm), the reference electrode is Ag / AgCl, and the working electrode is the graphite-polypyrrole electrode synthesized in step (1). Electropolymerization is carried out by cyclic voltammetry. The low voltage is set to -0.5V, the high voltage range is set to 0.6V, the cyclic scanning is 80 cycles, the scanning speed range is 50mV / s, and after the reaction is completed, the electrode material based on non-heme iron catalyst is obtained.

[0045] Application Example 1: Electrocatalytic Degradation of Bisphenol A: 5 mg / L of bisphenol A was dissolved in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). An electrocatalytic degradation experiment was conducted in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical reactor. The counter electrode was a platinum sheet (10 × 10 × 0.1 mm), the reference electrode was Ag / AgCl, and the working electrode was the electrode material based on a non-heme iron catalyst synthesized in Example 1. All electrodes were spaced 2 cm apart. The temperature was controlled at 30 °C, the stirring speed at 500 rpm, and the oxygen aeration flow rate at 20 mL / min. A constant potential was applied to the working electrode using an electrochemical workstation, with the voltage set to -1.0 V. After 1.5 hours, the removal rate of bisphenol A reached 100%.

[0046] The reaction mechanism diagram of non-heme iron catalysts and auxiliary ligands with H2O2 is shown below. Figure 1 As shown, the non-heme iron catalyst enhances the yield of hydrogen peroxide from the two-electron reduction of oxygen by the graphite electrode, while the auxiliary ligand regulates the single-electron reduction of oxygen by the non-heme iron catalyst to generate superoxide radicals. Under the catalysis of the non-heme iron catalyst, the superoxide radicals react with hydrogen peroxide to produce hydroxyl radicals with higher oxidizing power.

[0047] Application Example 2: Electrocatalytic Degradation of Bisphenol A: 5 mg / L of bisphenol A was dissolved in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). An electrocatalytic degradation experiment was conducted in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical reactor. The counter electrode was a platinum sheet (10 × 10 × 0.1 mm), the reference electrode was Ag / AgCl, and the working electrode was the electrode material based on a non-heme iron catalyst synthesized in Example 2. All electrodes were spaced 2 cm apart. The temperature was controlled at 30 °C, the stirring speed at 500 rpm, and the oxygen aeration flow rate at 20 mL / min. A constant potential was applied to the working electrode using an electrochemical workstation, with the voltage set to -0.5 V. After 1.5 hours, the removal rate of bisphenol A was 95%.

[0048] Comparative Example 1: Graphite material was used.

[0049] Comparative Example 1: Electrocatalytic Degradation of Bisphenol A: 5 mg / L of bisphenol A was dissolved in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). Electrocatalytic degradation experiments were conducted in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical reactor. The counter electrode was a platinum sheet (10 × 10 × 0.1 mm), the reference electrode was Ag / AgCl, and the working electrode was the graphite material from Comparative Example 1. All electrodes were spaced 2 cm apart. The temperature was controlled at 30 °C, the stirring speed at 500 rpm, and the oxygen aeration flow rate at 20 mL / min. A constant potential was applied to the working electrode using an electrochemical workstation, with the voltage set to -1.0 V. After 1.5 hours, the removal rate of bisphenol A was 21%.

[0050] Comparative Example 2: The electrode material based on a non-heme iron catalyst-non-layered material provided in this embodiment uses graphite as a substrate, on which polypyrrole and non-heme iron catalysts are simultaneously deposited. The preparation steps of the above electrode material are as follows:

[0051] (1) Preparation of non-heme iron catalyst precursor (containing pyrrole) solution: Weigh 5 mM dopamine hydrochloride and dissolve it in 20 mM PBS solution, add 1 mM FeCl2, add 5 mM pyrrole monomer, aerate with nitrogen for 10 min, nitrogen flow rate is 100 mL / min, stir thoroughly, so that ferrous ions and dopamine are linked through Fe-O bond to form non-heme iron catalyst monomer, and obtain non-heme iron catalyst precursor solution;

[0052] (2) Preparation of electrode material based on non-heme iron catalyst: The non-heme iron catalyst precursor solution in step (2) was used as the electrolyte, and electropolymerization was carried out in a three-electrode system. The counter electrode was a platinum sheet (10×10×0.1mm), the reference electrode was Ag / AgCl, and the working electrode was the graphite-polypyrrole electrode synthesized in step (1). Electropolymerization was carried out by cyclic voltammetry. The low voltage was set to -0.5V, the high voltage range was set to 0.8V, the cyclic scanning was 50 times, and the scanning speed range was 20mV / s. After the reaction was completed, the electrode material based on non-heme iron catalyst was soaked for 20 hours. After the reaction was completed, the electrode material was thoroughly washed with ultrapure water to obtain the electrode material based on non-heme iron catalyst.

[0053] Comparative Example 2: Electrocatalytic Degradation of Bisphenol A: 5 mg / L of bisphenol A was dissolved in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). Electrocatalytic degradation experiments were conducted in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical reactor. The counter electrode was a platinum sheet (10 × 10 × 0.1 mm), the reference electrode was Ag / AgCl, and the working electrode was the electrode material synthesized in Comparative Example 2. All electrodes were spaced 2 cm apart. The temperature was controlled at 30 °C, the stirring speed at 500 rpm, and the oxygen aeration flow rate at 20 mL / min. A constant potential was applied to the working electrode using an electrochemical workstation, with the voltage set to -1.0 V. After 1.5 hours, the removal rate of bisphenol A was 56%.

[0054] Comparative Example 3: The electrode material based on non-heme iron catalyst - outer layer only provided in this embodiment is based on graphite, on which a non-heme iron catalyst layer is deposited. The non-heme iron catalyst layer is obtained by reacting ferrous salt and dopamine, with a molar ratio of ferrous salt to dopamine of 0.2:1.

[0055] The preparation steps of the above electrode material are as follows:

[0056] (1) Preparation of non-heme iron catalyst precursor solution: Weigh 5 mM dopamine hydrochloride and dissolve it in 20 mM PBS solution, add 1 mM FeCl2, aerate with nitrogen for 10 min at a nitrogen flow rate of 100 mL / min, stir thoroughly so that ferrous ions and dopamine are linked through Fe-O bonds to form non-heme iron catalyst monomer, and obtain non-heme iron catalyst precursor solution;

[0057] (2) Preparation of electrode material based on non-heme iron catalyst: The non-heme iron catalyst precursor solution in step (2) was used as the electrolyte, and electropolymerization was carried out in a three-electrode system. The counter electrode was a platinum sheet (10×10×0.1mm), the reference electrode was Ag / AgCl, and the working electrode was the graphite-polypyrrole electrode synthesized in step (1). Electropolymerization was carried out by cyclic voltammetry. The low voltage was set to -0.5V, the high voltage range was set to 0.8V, the cyclic scanning was 50 times, and the scanning speed range was 20mV / s. After the reaction was completed, the electrode material based on non-heme iron catalyst was soaked for 20 hours. After the reaction was completed, the electrode material was thoroughly washed with ultrapure water to obtain the electrode material based on non-heme iron catalyst.

[0058] Comparative Example 3: Electrocatalytic Degradation of Bisphenol A: 5 mg / L of bisphenol A was dissolved in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). Electrocatalytic degradation experiments were conducted in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical reactor. The counter electrode was a platinum sheet (10 × 10 × 0.1 mm), the reference electrode was Ag / AgCl, and the working electrode was the electrode material synthesized in Comparative Example 3. All electrodes were spaced 2 cm apart. The temperature was controlled at 30 °C, the stirring speed at 500 rpm, and the oxygen aeration flow rate at 20 mL / min. A constant potential was applied to the working electrode using an electrochemical workstation, with the voltage set to -1.0 V. After 1.5 hours, the removal rate of bisphenol A was 66%.

[0059] XPS tests were performed on the materials prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. The results are shown in the figure. Figure 2 Compared with the graphite electrode in Comparative Example 1, the non-heme iron catalyst electrodes in Comparative Example 2, Comparative Example 3 and Example 1 have increased iron and nitrogen elements.

[0060] Electrocatalytic performance tests were conducted on Application Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. The results are shown in [Figure Number]. Figures 3-5 , Figure 3 The results showed that, compared with the graphite electrode in Comparative Example 1, the amount of hydrogen peroxide generated by the non-heme iron catalyst electrodes in Comparative Example 2, Comparative Example 3 and Example 1 was increased by 3 times. Figure 4 The results show that only under the condition of layered polymerization of polypyrrole and non-heme iron catalyst can the generation of superoxide radicals from oxygen be regulated. Figure 5 The results showed that, compared with the graphite electrode, the bisphenol A removal rates of Comparative Example 2, Comparative Example 3 and Example 1 were significantly improved. Among them, the performance of Example 1 was the best, with the electrocatalytic removal rate of bisphenol A increasing by 20 times.

[0061] Example 3: The difference from Example 1 is that the molar ratio of ferrous salt to dopamine is 0.14:1.

[0062] Example 4: The difference from Example 1 is that the molar ratio of ferrous salt to dopamine is 0.4:1.

[0063] Example 5: The difference from Example 1 is that the molar ratio of ferrous salt to dopamine is 0.6:1.

[0064] Example 6: The difference from Example 1 is that the molar ratio of ferrous salt to dopamine is 0.8:1.

[0065] Example 7: The difference from Example 1 is that the molar ratio of ferrous salt to dopamine is 1.0:1.

[0066] Comparative Example 4: The difference from Example 1 is that the molar ratio of ferrous salt to dopamine is 0.1:1.

[0067] Comparative Example 5: The difference from Example 1 is that the molar ratio of ferrous salt to dopamine is 0.06:1.

[0068] Comparative Example 6: The difference from Example 1 is that it does not include ferrous salts.

[0069] The electrocatalytic degradation methods of bisphenol A in Application Examples 3-7 and Comparative Examples 4-6 are the same as in Application Example 1, except that the working electrodes are the electrode materials prepared in Examples 3-7 and Comparative Examples 4-6, respectively.

[0070] The degradation effects of Application Examples 3-7 and Application Comparative Examples 2-4 are shown in the figure. Figure 6 . Figure 6 The results showed that when the ratio of ferrous chloride to dopamine was greater than 0.14:1, the electrocatalytic removal rate of bisphenol A by the non-heme iron catalyst remained at a high level.

[0071] Application Example 8: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 2.

[0072] Application Example 9: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 3.

[0073] Application Example 10: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 4.

[0074] Application Example 11: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 5.

[0075] Application Example 12: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 6.

[0076] Application Comparative Example 7: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 6.5.

[0077] Application Comparative Example 8: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 7.

[0078] Comparative Example 9: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 7.5.

[0079] Comparative Example 10: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 8.

[0080] Comparative Example 11: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 9.

[0081] Comparative Example 12: The difference from Application Example 1 is that the pH of the sodium sulfate solution containing bisphenol A is adjusted to 10.

[0082] The degradation effects of Application Examples 1, 8-12, and 7-12 are shown in the figure. Figure 7 .Depend on Figure 7 It can be seen that the electrocatalytic removal rate of bisphenol A by non-heme iron catalysts remained at a high level under conditions of pH 2-6, while the rate of bisphenol A removal by non-heme iron catalysts decreased significantly under conditions of pH 6.5-10. This is because the generation of hydroxyl radicals is limited under high pH conditions, and the oxidizing power of hydroxyl radicals is significantly weakened.

[0083] Application Example 13: The difference from Application Example 1 is that the voltage is set to -0.9V.

[0084] Application Example 14: The difference from Application Example 1 is that the voltage is set to -0.8V.

[0085] Application Example 15: The difference from Application Example 1 is that the voltage is set to -0.7V.

[0086] Application Example 16: The difference from Application Example 1 is that the voltage is set to -0.6V.

[0087] Application Example 17: The difference from Application Example 1 is that the voltage is set to -0.5V.

[0088] Comparative Application Example 13: The difference from Application Example 1 is that the voltage is set to -0.4V.

[0089] Comparative Application Example 14: The difference from Application Example 1 is that the voltage is set to -0.3V.

[0090] Comparative Example 15: The difference from Application Example 1 is that the voltage is set to -0.2V.

[0091] Comparative Application Example 16: The difference from Application Example 1 is that the voltage is set to -0.1V.

[0092] The degradation effects of Application Examples 1, 13-17, and 13-16 are shown in the figure. Figure 8 .Depend on Figure 8 It can be seen that the electrocatalytic removal rate of bisphenol A by non-heme iron catalysts remains at a high level when the voltage is below -0.5V. This is because the onset potential for hydrogen peroxide generation is -0.5V, and when the voltage is above -0.5V, the generation of hydrogen peroxide is limited.

[0093] Example 18: The electrode material based on a non-heme iron catalyst provided in this example uses graphite as a substrate, on which a polyfuran layer and a non-heme iron catalyst layer are sequentially deposited. The non-heme iron catalyst layer is obtained by reacting ferrous salt and dopamine, with a molar ratio of ferrous salt to dopamine of 0.2:1.

[0094] The preparation steps of the above electrode material are as follows:

[0095] (1) Preparation of graphite-polyfuran electrode material: 5 mM of furan monomer was dissolved in acetonitrile, and 0.1 M tetrabutylammonium perchlorate was used as the electrolyte. The working electrode was a glassy carbon electrode, and the reference electrode was Ag / Ag. + The electrodes were platinum wire for the counter electrode. The polymerization potential was determined by differential pulse voltammetry, with a scan range of 0-3V. The potential at which the oxidation peak appeared was the polymerization potential of furan. 5 mM furan monomer was dissolved in acetonitrile, and 0.1 M tetrabutylammonium perchlorate was used as the electrolyte. The working electrode was a graphite electrode (40×25×2 mm), and the reference electrode was Ag / Ag. + The electrode and the counter electrode are platinum sheet electrodes (10×10×0.1mm). A constant potential is applied, which is set according to the polymerization potential of furan, and the time is set to 1h.

[0096] (2) Preparation of non-heme iron catalyst precursor solution: Weigh 5 mM dopamine hydrochloride and dissolve it in 20 mM PBS solution, add 1 mM FeCl2, aerate with nitrogen for 10 min at a flow rate of 100 mL / min, stir thoroughly so that ferrous ions and dopamine are linked through Fe-O bonds to form non-heme iron catalyst monomer, and obtain non-heme iron catalyst precursor solution;

[0097] (3) Preparation of electrode material based on non-heme iron catalyst: The non-heme iron catalyst precursor solution in step (2) is used as the electrolyte, and electropolymerization is carried out in a three-electrode system. The counter electrode is a platinum sheet (10×10×0.1mm), the reference electrode is Ag / AgCl, and the working electrode is the graphite-polyfuran electrode synthesized in step (1). Electropolymerization is carried out by cyclic voltammetry. The low voltage is set to -0.5V, the high voltage range is set to 0.8V, the cyclic scan is 50 times, the scan speed range is 20mV / s, and after the reaction is completed, it is soaked for 10 hours. After the reaction is completed, it is thoroughly washed with ultrapure water to obtain the electrode material based on non-heme iron catalyst.

[0098] Application Example 18: Electrocatalytic Degradation of Bisphenol A: 5 mg / L of bisphenol A was dissolved in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). An electrocatalytic degradation experiment was conducted in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical reactor. The counter electrode was a platinum sheet (10 × 10 × 0.1 mm), the reference electrode was Ag / AgCl, and the working electrode was the electrode material based on a non-heme iron catalyst synthesized in Example 18. All electrodes were spaced 2 cm apart. The temperature was controlled at 30 °C, the stirring speed at 500 rpm, and the oxygen aeration flow rate at 20 mL / min. A constant potential was applied to the working electrode using an electrochemical workstation, with the voltage set to -1.0 V. After 1.5 hours, the removal rate of bisphenol A was 75%.

[0099] Example 19: The difference from Example 18 is that the monomer of the auxiliary ligand polymerization layer is selected as thiophene.

[0100] Example 20: The difference from Example 18 is that the monomer of the auxiliary ligand polymerization layer is 2-thiophene methylamine.

[0101] Example 21: The difference from Example 18 is that the monomer of the auxiliary ligand polymerization layer is N-methyl-2-thiophene methylamine.

[0102] Example 22: The difference from Example 18 is that the monomer of the auxiliary ligand polymerization layer is (S)-N,N-dimethyl-3-hydroxy-3-(2-thienyl)propylamine.

[0103] Example 23: The difference from Example 18 is that the monomer of the auxiliary ligand polymerization layer is selected as 2-nitrothiophene.

[0104] The methods used in Application Examples 19-23 are the same as those in Application Example 18, except that the electrode materials used are the same as those prepared in the corresponding examples.

[0105] The degradation effects of Application Examples 18-23 are shown in the figure. Figure 9 .Depend on Figure 9It is known that monomer polymers with thiophene rings can increase the rate of bisphenol A degradation in water by non-heme iron catalysts, and the degradation rate is related to the type of functional groups on the monomers in the auxiliary ligand polymerization layer.

Claims

1. An electrode material based on a non-heme iron catalyst, characterized in that, Using an electrode material as a substrate, an auxiliary ligand polymer layer and a non-heme iron catalyst layer are sequentially deposited on the substrate. The auxiliary ligand polymer layer is polymerized from organic monomers, and the non-heme iron catalyst layer is obtained by electrochemical polymerization of a precursor formed by the reaction of ferrous salt and dopamine. The auxiliary ligand polymer layer and the non-heme iron catalyst layer are connected by coordination bonds. The organic monomers are polymerizable organic monomers with thiophene rings, furan rings, or pyrrole rings.

2. The electrode material based on a non-heme iron catalyst according to claim 1, characterized in that, In the non-heme iron catalyst layer, the molar ratio of ferrous salt to dopamine is 0.14:1-2:

1.

3. A method for preparing the electrode material based on a non-heme iron catalyst as described in claim 1, characterized in that, Includes the following steps: (1) The organic monomer is fully dissolved in an organic solvent, and after deoxygenation treatment, it is electropolymerized in a three-electrode system by cyclic voltammetry or constant potential polymerization to electropolymerize the organic monomer onto the surface of the electrode material to obtain an electrode material with an auxiliary ligand polymerization layer. (2) Dissolve dopamine hydrochloride in a solvent, remove oxygen, add ferrous salt, stir thoroughly, and prepare a non-heme iron catalyst precursor solution. (3) Using the non-heme iron catalyst precursor solution as the electrolyte and the electrode material with the auxiliary ligand polymerization layer as the working electrode, electropolymerization is carried out in a three-electrode system by cyclic voltammetry to electropolymerize the non-heme iron catalyst onto the surface of the electrode material with the auxiliary ligand polymerization layer. After the electropolymerization is completed, the electrode material based on the non-heme iron catalyst is obtained by soaking it thoroughly.

4. The preparation method according to claim 3, characterized in that, In steps (1) and (2), the process parameters for the deoxygenation treatment are: nitrogen aeration for 10-20 min, and nitrogen flow rate per liter of solution is 1-10 mL / min.

5. The preparation method according to claim 3, characterized in that, In step (1), the molar concentration of the organic monomer in the organic solvent is 1-20 mM.

6. The preparation method according to claim 3, characterized in that, In step (2), the molar concentration of dopamine hydrochloride in the solvent is 5-10 mM; the solvent is a phosphate buffer with a molar concentration of 20-100 mM.

7. The preparation method according to claim 3, characterized in that, In step (3), the soaking parameters are: 5-30h.

8. The application of the electrode material based on a non-heme iron catalyst as described in claim 1 in the field of electro-Fenton degradation of pollutants.

9. The application according to claim 8, characterized in that, The application method is as follows: using electrode materials based on non-heme iron catalysts as working electrodes and water containing pollutants as electrolytes, an electrocatalytic degradation reaction is carried out in a three-electrode system.

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