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

Abstract

The invention discloses an electrode material based on a non-heme iron catalyst and a preparation method and application thereof, and belongs to the field of electro-catalysis water treatment. According to the material, an electrode material is used as a substrate, an auxiliary ligand polymerization layer and a non-heme iron catalyst layer are sequentially deposited on the substrate, the auxiliary ligand polymerization layer is formed by polymerizing organic matter monomers, the non-heme iron catalyst layer is obtained by reacting ferrite and dopamine to form a precursor, and then electrochemical polymerization is performed, the auxiliary ligand polymerization layer is connected with the non-heme iron catalyst layer through a coordination bond. The auxiliary ligand polymerization layer and the non-heme iron catalyst are electrically polymerized on the electrode material, so that the selectivity of the electrode material for producing hydrogen peroxide through electro-catalysis oxygen two-electron reduction is improved, and the yield of hydrogen peroxide is increased. In addition, the non-heme iron catalyst can further generate superoxide free radicals by regulating and controlling single electron reduction of oxygen, hydrogen peroxide is promoted to generate hydroxyl free radicals, and good electro-catalysis organic pollutant removal efficiency is kept under the nearly neutral condition.

Description

Technical Field

[0001] The invention relates to the field of electrocatalytic water treatment, and in particular to an electrode material based on a non-heme iron catalyst, and a preparation method and application thereof. Background Art

[0002] Conventional sewage treatment processes cannot effectively remove difficult-to-degrade, high-risk organic pollutants in sewage, and the discharge of such pollutants into the environment will bring huge health risks. Electrocatalytic technology can rely on the strong electron-withdrawing ability of the anode to directly oxidize pollutants, or rely on the negative potential of the cathode to reduce oxygen to produce active oxygen species (such as hydroxyl radicals) and indirectly oxidize pollutants. Electrocatalytic technology based on direct oxidation at the anode will be affected by electrode contamination, while electrocatalytic technology based on indirect oxidation at the cathode has received widespread attention due to its high oxidation activity.

[0003] There are two main pathways for the electrocatalytic reduction of oxygen, including four-electron reduction to produce water and two-electron reduction to produce hydrogen peroxide. The significant thermodynamic advantage of four-electron reduction leads to low hydrogen peroxide yield. On the other hand, hydrogen peroxide is difficult to directly remove pollutants due to its inherent low oxidizability. Fenton and Fenton-like catalysts can activate hydrogen peroxide to produce active oxygen species such as hydroxyl radicals or singlet oxygen, but the activity of most catalysts is limited by pH and can only maintain high activity under acidic conditions, which greatly limits the application of electrocatalytic oxygen activation technology.

[0004] The existing electro-Fenton technology produces hydrogen peroxide by reducing oxygen at the cathode, and then adding Fe 2+ The Fenton reaction occurs with the hydrogen peroxide generated in situ to produce hydroxyl radicals with strong oxidizing properties, thereby achieving efficient removal of organic pollutants. In this technology, the cathode can not only be used to reduce oxygen to produce hydrogen peroxide, but also to reduce Fe 3+ Produces Fe 2+ , achieving the purpose of accelerating the Fenton reaction. However, in the electro-Fenton technology, the yield of hydrogen peroxide is low due to the thermodynamic advantage of the oxygen four-electron reaction. In addition, the activity of the Fenton reaction will drop sharply when the pH exceeds 3, and iron sludge will be produced, causing secondary pollution. Summary of the invention

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

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

[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-thienyl)propylamine, N-methyl-2-thiophenemethylamine or 2-thiophenemethylamine.

[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 the present invention, the catalytic performance of the non-heme iron catalyst is based on iron as the active center, but due to the strong interaction between the iron center and oxygen, the formed iron dioxygen species tend to selectively break the OO bond, inhibiting the generation of superoxide radicals. The nitrogen, oxygen or sulfur functional groups in the pyrrole ring, furan ring or thiophene ring in the auxiliary ligand polymerization layer can form a coordination bond with the iron center, enhance the electron cloud density of the iron center, weaken the stability of the Fe-O bond, thereby retaining the OO bond and promoting the generation of superoxide radicals.

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

[0012] (1) fully dissolving an organic monomer in an organic solvent, deoxygenating the organic monomer, and then electropolymerizing the organic monomer to the surface of an electrode material by cyclic voltammetry or constant potential polymerization in a three-electrode system to obtain an electrode material having an auxiliary ligand polymerization layer;

[0013] (2) dissolving dopamine hydrochloride in a solvent, deoxygenating it, adding ferrous salt, and stirring it thoroughly to obtain a non-heme iron catalyst precursor solution;

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

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

[0016] Furthermore, 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 tetrabutylammonium perchlorate or a phosphate buffer with a molar concentration of 20-100 mM.

[0017] Furthermore, 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] Furthermore, in step (1) and step (3), the process parameters of the cyclic voltammetry electropolymerization are: the low voltage setting range is -0.8 to -0.2 V, the high voltage setting range is 0.6 to 1.0 V, the cycle scan is 10-100 circles, and the scanning speed range is 10-100 mV / s; in step (1), the electropolymerization process parameters of the constant potential polymerization method are: weigh 1-20 mM of the auxiliary ligand monomer and dissolve it in acetonitrile, use 10-500 mM of tetrabutylammonium perchlorate as the electrolyte, the working electrode is a glassy carbon electrode, and the reference electrode is Ag / Ag + The electrode is a platinum wire, and 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 the constant potential polymerization process. The time is set to 5min-1h. In step (3), the immersion parameter is: 5-30h.

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

[0020] Furthermore, the application method is: using the electrode material based on the non-heme iron catalyst as the working electrode, using the water containing the pollutants as the electrolyte, and performing an electrocatalytic degradation reaction 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 interval between each electrode is 2-3 cm; the process parameters of the electrocatalytic degradation reaction are: the control temperature is 30-35°C, the stirring speed is 500-1000rpm, the oxygen aeration flow rate is 20-25mL / min, and a constant potential is applied to the working electrode through an electrochemical workstation, and the voltage is set to -0.5V to -1.5V.

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

[0023] Principle of the invention: The present invention electropolymerizes an auxiliary ligand polymerization layer and a non-heme iron catalyst on the electrode material, thereby improving the selectivity of the electrode electrocatalytic two-electron reduction of oxygen to produce hydrogen peroxide and increasing the yield of hydrogen peroxide. In addition, the non-heme iron catalyst can further produce superoxide radicals by regulating the one-electron reduction of oxygen, promote hydrogen peroxide to produce hydroxyl radicals, and maintain a good efficiency of 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 catalyzed by the electrode material based on the non-heme iron catalyst of the present invention is significantly improved. After 1.5 hours, the hydrogen peroxide catalyzed by the blank graphite electrode is 4.9 mg / L, and the hydrogen peroxide catalyzed by the non-heme iron catalyst is 15.8 mg / L, which is 222.4% higher than that of the blank graphite. (2) Compared with the blank graphite electrode, the rate of electrocatalytic removal of bisphenol A by the electrode material based on the non-heme iron catalyst of the present invention is significantly improved. In the non-heme iron catalyst, the removal rate of bisphenol A reaches up to 3.24 h -1 , while blank graphite only has 0.20h -1 ; (3) Compared with the conventional electro-Fenton technology which can only maintain good effect under the condition of pH < 3, the electrode material based on the non-heme iron catalyst of the present invention still maintains a high bisphenol A removal rate under the condition of pH < 6; (4) The electrode material based on the non-heme iron catalyst of the present invention still maintains good BPA removal performance under a lower potential (-0.5V). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The diagram is the reaction mechanism of non-heme iron catalyst and auxiliary ligand with H2O2;

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

[0027] Figure 3 A concentration diagram of hydrogen peroxide generated by electrocatalysis of the electrode materials in Comparative Examples 1 to Comparative Examples 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 to 3 and the non-heme iron catalyst electrode in Example 1 for electrocatalysis of superoxide radicals;

[0029] Figure 5 It is a rate diagram of electrocatalytic removal of bisphenol A by the electrode materials in Comparative Examples 1 to Comparative Examples 3 and the non-heme iron catalyst electrode in Example 1;

[0030] Figure 6 Rate diagram of electrocatalytic removal of bisphenol A by non-heme iron catalyst electrode prepared with different molar ratios of ferrous chloride and dopamine;

[0031] Figure 7 The rate diagram of electrocatalytic removal of bisphenol A by non-heme iron catalyst electrode at different pH;

[0032] Figure 8 The rate diagram of electrocatalytic removal of bisphenol A by non-heme iron catalyst electrode at different voltages;

[0033] Fig. 9 The rate diagram of electrocatalytic removal of bisphenol A based on non-heme iron catalyst electrode with different auxiliary ligands. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments and drawings.

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

[0036] The preparation method of the above electrode material has the following steps:

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

[0038] (2) preparing a non-heme iron catalyst precursor solution: weighing 5 mM dopamine hydrochloride and dissolving it in a 20 mM PBS solution, adding 1 mM FeCl2, exposing to nitrogen for 10 min at a nitrogen flow rate of 100 mL / min, and stirring sufficiently to allow ferrous ions to connect with dopamine through Fe-O bonds to form a non-heme iron catalyst monomer, thereby preparing a non-heme iron catalyst precursor solution;

[0039] (3) Preparation of electrode materials based on non-heme iron catalysts: Using the non-heme iron catalyst precursor solution in step (2) as an electrolyte, electropolymerization is carried out in a three-electrode system, wherein the counter electrode is a platinum sheet (10×10×0.1 mm), 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, wherein the low voltage is set to -0.5 V, the high voltage range is set to 0.8 V, the cycle scan is 50 times, the scan speed range is 20 mV / s, and the soaking is continued for 10 hours after the reaction is completed. After the reaction is completed, it is thoroughly washed with ultrapure water to obtain an electrode material based on a non-heme iron catalyst.

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

[0041] The preparation method of the above electrode material has the following steps:

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

[0043] (2) preparing a non-heme iron catalyst precursor solution: weighing 10 mM dopamine hydrochloride and dissolving it in 20 mM PBS solution, adding 5 mM FeCl2, exposing to nitrogen for 10 min at a nitrogen flow rate of 100 mL / min, and stirring sufficiently to allow ferrous ions to connect with dopamine through Fe-O bonds to form a non-heme iron catalyst monomer, thereby preparing a non-heme iron catalyst precursor solution;

[0044] (3) Preparation of electrode materials based on non-heme iron catalysts: Using the non-heme iron catalyst precursor solution in step (2) as an electrolyte, electropolymerization is carried out in a three-electrode system, wherein the counter electrode is a platinum sheet (10×10×0.1 mm), 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, wherein the low voltage is set to -0.5 V, the high voltage range is set to 0.6 V, the cycle scan is 80 times, the scan speed range is 50 mV / s, and the soaking is continued for 20 hours after the reaction is completed. After the reaction is completed, it is thoroughly washed with ultrapure water to obtain an electrode material based on a non-heme iron catalyst.

[0045] Application Example 1: Electrocatalytic degradation of bisphenol A: Weigh 5 mg / L of bisphenol A and dissolve it in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). The electrocatalytic degradation experiment was carried out in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical type, 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 the non-heme iron catalyst synthesized in Example 1. Each electrode was 2 cm apart. The temperature was controlled to be 30°C, the stirring speed was 500 rpm, the oxygen aeration flow rate was 20 mL / min, and a constant potential was applied to the working electrode through an electrochemical workstation, the voltage was set to -1.0 V, and the removal rate of bisphenol A was 100% after 1.5 hours.

[0046] The reaction mechanism of non-heme iron catalyst and auxiliary ligand with H2O2 is shown in the figure Figure 1 As shown, the non-heme iron catalyst improves the yield of hydrogen peroxide from the two-electron reduction of oxygen on the graphite electrode, while the auxiliary ligand regulates the non-heme iron catalyst to produce superoxide radicals from the one-electron reduction of oxygen on the non-heme iron catalyst. Under the catalytic action of the non-heme iron catalyst, the superoxide radical reacts with hydrogen peroxide to produce hydroxyl radicals with higher oxidizing power.

[0047] Application Example 2: Electrocatalytic degradation of bisphenol A: Weigh 5 mg / L of bisphenol A and dissolve it in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). The electrocatalytic degradation experiment was carried out in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical type, 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 the non-heme iron catalyst synthesized in Example 2. Each electrode was 2 cm apart. The temperature was controlled to 30°C, the stirring speed was 500 rpm, the oxygen aeration flow rate was 20 mL / min, and a constant potential was applied to the working electrode through an electrochemical workstation, the voltage was set to -0.5 V, and the removal rate of bisphenol A was 95% after 1.5 hours.

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

[0049] Application Comparative Example 1: Electrocatalytic degradation of bisphenol A: Weigh 5 mg / L of bisphenol A and dissolve it in 0.05M sodium sulfate solution (natural pH ≈ 5.8). The electrocatalytic degradation experiment was carried out in a three-electrode system. The electrochemical reactor was a 100mL cylindrical type, the counter electrode was a platinum sheet (10×10×0.1mm), the reference electrode was Ag / AgCl, and the working electrode was the graphite material in Comparative Example 1. Each electrode was 2 cm apart. The temperature was controlled to be 30°C, the stirring speed was 500rpm, the oxygen aeration flow rate was 20mL / min, and a constant potential was applied to the working electrode through an electrochemical workstation, the voltage was set to -1.0V, and the removal rate of bisphenol A was 21% after 1.5 hours.

[0050] Comparative Example 2: The electrode material based on non-heme iron catalyst-non-layered provided in this embodiment is based on graphite as a substrate, and polypyrrole and non-heme iron catalyst are deposited on the substrate at the same time. The preparation method of the electrode material is as follows:

[0051] (1) preparing a non-heme iron catalyst precursor (containing pyrrole) solution: weighing 5 mM dopamine hydrochloride and dissolving it in a 20 mM PBS solution, adding 1 mM FeCl2, adding 5 mM pyrrole monomer, exposing to nitrogen for 10 min at a nitrogen flow rate of 100 mL / min, and stirring sufficiently to allow ferrous ions to connect with dopamine through Fe-O bonds to form a non-heme iron catalyst monomer, thereby preparing a non-heme iron catalyst precursor solution;

[0052] (2) Preparation of electrode materials based on non-heme iron catalysts: Using the non-heme iron catalyst precursor solution in step (2) as an electrolyte, electropolymerization is carried out in a three-electrode system, wherein the counter electrode is a platinum sheet (10×10×0.1 mm), 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, wherein the low voltage is set to -0.5 V, the high voltage range is set to 0.8 V, the cycle scan is 50 times, the scan speed range is 20 mV / s, and the soaking is continued for 20 hours after the reaction is completed. After the reaction is completed, it is thoroughly washed with ultrapure water to obtain an electrode material based on a non-heme iron catalyst.

[0053] Application Comparative Example 2: Electrocatalytic degradation of bisphenol A: Weigh 5 mg / L of bisphenol A and dissolve it in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). The electrocatalytic degradation experiment was carried out in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical type, 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. Each electrode was 2 cm apart. The temperature was controlled at 30°C, the stirring speed was 500 rpm, the oxygen aeration flow rate was 20 mL / min, and a constant potential was applied to the working electrode through an electrochemical workstation, the voltage was set to -1.0 V, and the removal rate of bisphenol A was 56% after 1.5 hours.

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

[0055] The preparation method of the above electrode material has the following steps:

[0056] (1) preparing a non-heme iron catalyst precursor solution: weighing 5 mM dopamine hydrochloride and dissolving it in a 20 mM PBS solution, adding 1 mM FeCl2, exposing to nitrogen for 10 min at a nitrogen flow rate of 100 mL / min, and stirring sufficiently to allow ferrous ions to connect with dopamine through Fe-O bonds to form a non-heme iron catalyst monomer, thereby preparing a non-heme iron catalyst precursor solution;

[0057] (2) Preparation of electrode materials based on non-heme iron catalysts: Using the non-heme iron catalyst precursor solution in step (2) as an electrolyte, electropolymerization is carried out in a three-electrode system, wherein the counter electrode is a platinum sheet (10×10×0.1 mm), 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, wherein the low voltage is set to -0.5 V, the high voltage range is set to 0.8 V, the cycle scan is 50 times, the scan speed range is 20 mV / s, and the soaking is continued for 20 hours after the reaction is completed. After the reaction is completed, it is thoroughly washed with ultrapure water to obtain an electrode material based on a non-heme iron catalyst.

[0058] Application Comparative Example 3: Electrocatalytic degradation of bisphenol A: Weigh 5 mg / L of bisphenol A and dissolve it in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). The electrocatalytic degradation experiment was carried out in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical type, 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. Each electrode was 2 cm apart. The temperature was controlled at 30°C, the stirring speed was 500 rpm, the oxygen aeration flow rate was 20 mL / min, and a constant potential was applied to the working electrode through an electrochemical workstation, the voltage was set to -1.0 V, and the removal rate of bisphenol A was 66% after 1.5 hours.

[0059] XPS test was performed on the materials prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3. The results are shown in 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] The electrocatalytic performance of Application Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 was tested. The results are shown in Figure 3-Figure 5 , Figure 3 The results show that compared with the graphite electrode in Comparative Example 1, the amount of hydrogen peroxide electrocatalyzed by the non-heme iron catalyst electrode in Comparative Example 2, Comparative Example 3 and Example 1 is increased by 3 times. Figure 4 The results show that only under the conditions of layered polymerization of polypyrrole and non-heme iron catalyst can oxygen be regulated to produce superoxide radicals. Figure 5 The results show that compared with the graphite electrode, the removal rates of bisphenol A in Comparative Example 2, Comparative Example 3 and Example 1 are significantly improved, among which the performance in Example 1 is the best, and the electrocatalytic removal rate of bisphenol A is increased 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 no ferrous salt is included.

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

[0070] The degradation effects of Application Example 3 to Application Example 7 and Application Comparative Example 2 to Application Comparative Example 4 are shown in Figure 6 . Figure 6 The results show that when the formula ratio of ferrous chloride to dopamine is greater than 0.14:1, the rate of electrocatalytic removal of bisphenol A by non-heme iron catalyst remains 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] Application 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] Application 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] Application 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] Application 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 example 1, application example 8 to application example 12 and application comparative example 7 to application comparative example 12 are shown in Figure 7 .Depend on Figure 7 It can be seen that under the condition of pH = 2-6, the rate of electrocatalytic removal of bisphenol A by non-heme iron catalysts is maintained at a high level, while under the condition of pH = 6.5-10, the rate of electrocatalytic removal of bisphenol A by non-heme iron catalysts is significantly reduced. This is because the generation of hydroxyl radicals is limited under high pH conditions, and the oxidizing property 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] Application Comparative Example 13: The difference from Application Example 1 is that the voltage is set to -0.4V.

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

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

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

[0092] The degradation effects of application example 1, application example 13 to application example 17 and application comparative example 13 to application comparative example 16 are shown in Figure 8 .Depend on Figure 8 It can be seen that the rate of electrocatalytic removal of bisphenol A by non-heme iron catalysts is maintained at a high level when the voltage is lower than -0.5 V. This is because the starting potential of hydrogen peroxide generation is at -0.5 V. When the voltage is higher than -0.5 V, the generation of hydrogen peroxide is limited.

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

[0094] The preparation method of the above electrode material has the following steps:

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

[0096] (2) preparing a non-heme iron catalyst precursor solution: weighing 5 mM dopamine hydrochloride and dissolving it in a 20 mM PBS solution, adding 1 mM FeCl2, exposing to nitrogen for 10 min at a nitrogen flow rate of 100 mL / min, and stirring sufficiently to allow ferrous ions to connect with dopamine through Fe-O bonds to form a non-heme iron catalyst monomer, thereby preparing a non-heme iron catalyst precursor solution;

[0097] (3) Preparation of electrode materials based on non-heme iron catalysts: Using the non-heme iron catalyst precursor solution in step (2) as an electrolyte, electropolymerization is carried out in a three-electrode system, wherein the counter electrode is a platinum sheet (10×10×0.1 mm), 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, wherein the low voltage is set to -0.5 V, the high voltage range is set to 0.8 V, the cycle scan is 50 times, the scan speed range is 20 mV / s, and the soaking is continued for 10 hours after the reaction is completed. After the reaction is completed, it is thoroughly washed with ultrapure water to obtain an electrode material based on a non-heme iron catalyst.

[0098] Application Example 18: Electrocatalytic degradation of bisphenol A: Weigh 5 mg / L of bisphenol A and dissolve it in 0.05 M sodium sulfate solution (natural pH ≈ 5.8). The electrocatalytic degradation experiment was carried out in a three-electrode system. The electrochemical reactor was a 100 mL cylindrical type, 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 the non-heme iron catalyst synthesized in Example 18. Each electrode was 2 cm apart. The temperature was controlled to 30°C, the stirring speed was 500 rpm, the oxygen aeration flow rate was 20 mL / min, and a constant potential was applied to the working electrode through an electrochemical workstation, the voltage was set to -1.0 V, and the removal rate of bisphenol A was 75% after 1.5 hours.

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

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

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

[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 2-nitrothiophene.

[0104] The methods of Application Example 19 to Application Example 23 are the same as those of Application Example 18, and the electrode materials used are the electrode materials prepared in the corresponding examples.

[0105] The degradation effects of Application Examples 18 to 23 are shown in Fig. 9 .Depend on Fig. 9It can be seen that monomer polymers with thiophene rings can increase the rate of degradation of bisphenol A 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: With the electrode material as a substrate, an auxiliary ligand polymerization layer and a non-heme iron catalyst layer are sequentially deposited on the substrate, wherein the auxiliary ligand polymerization layer is formed by polymerization of organic monomers, and the non-heme iron catalyst layer is formed by the reaction of ferrous salt and dopamine to form a precursor, followed by electrochemical polymerization, and the auxiliary ligand polymerization layer and the non-heme iron catalyst layer are connected by coordination bonds.

2. The electrode material based on non-heme iron catalyst according to claim 1, characterized in that The organic monomer is a polymerizable organic monomer having a thiophene ring, a furan ring or a pyrrole ring.

3. The electrode material based on 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.

4. A method for preparing an electrode material based on a non-heme iron catalyst according to claim 1, characterized in that: The following steps are involved: (1) fully dissolving an organic monomer in an organic solvent, deoxygenating the organic monomer, and then electropolymerizing the organic monomer to the surface of an electrode material by cyclic voltammetry or constant potential polymerization in a three-electrode system to obtain an electrode material having an auxiliary ligand polymerization layer; (2) dissolving dopamine hydrochloride in a solvent, deoxygenating it, adding ferrous salt, and stirring it thoroughly to obtain a non-heme iron catalyst precursor solution; (3) Using the non-heme iron catalyst precursor solution as the electrolyte and the electrode material having the auxiliary ligand polymerization layer as the working electrode, electropolymerization is performed by cyclic voltammetry in a three-electrode system to electropolymerize the non-heme iron catalyst onto the surface of the electrode material having the auxiliary ligand polymerization layer. After the electropolymerization is completed, the electrode material is fully soaked to obtain an electrode material based on the non-heme iron catalyst.

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

6. The preparation method according to claim 4, characterized in that: In step (1), the molar concentration of the organic monomer in the organic solvent is 1-20 mM.

7. The preparation method according to claim 4, characterized in that: In step (2), the molar concentration of dopamine hydrochloride in the solvent is 5-10 mM; and the solvent is a phosphate buffer with a molar concentration of 20-100 mM.

8. The preparation method according to claim 4, characterized in that: In step (3), the soaking parameters are: 5-30h.

9. Use of the electrode material based on non-heme iron catalyst as claimed in claim 1 in the field of electro-Fenton degradation of pollutants.

10. The use according to claim 9, characterized in that: The application method is: using the electrode material based on the non-heme iron catalyst as the working electrode, using the water containing the pollutants as the electrolyte, and carrying out the electrocatalytic degradation reaction in the three-electrode system.

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