Iron-cobalt bimetallic anchored porous carbon electrode and preparation method thereof

Abstract

The application provides a kind of iron cobalt bimetallic anchoring porous carbon electrode and its preparation method, the load of cobalt in iron cobalt bimetallic anchoring porous carbon electrode is 0.5-2.5wt%, and the load of iron is 0.1-2.5wt%.Among them, the preparation method comprises the following steps: step S1, providing cobalt atom anchoring carbon electrode;Step S2, after acid etching, the cobalt atom anchoring carbon electrode is heat treated, and a cobalt atom anchoring porous carbon electrode is obtained;Step S3, the cobalt atom anchoring porous carbon electrode is immersed in an iron precursor solution and heat treated, and an iron cobalt bimetallic anchoring porous carbon electrode is obtained.The iron cobalt bimetallic anchoring porous carbon electrode according to the embodiment of the application can significantly improve the electrocatalytic activity of 3-electron oxygen reduction to ·OH, effectively reduce the dissolution of metal ions, and avoid the recovery problem of electrocatalyst, thereby more efficiently and greenly oxidizing and degrading new pollutants.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water and wastewater treatment, and particularly relates to an iron-cobalt bimetallic anchored porous carbon electrode and a preparation method thereof. BACKGROUND

[0002] At present, new pollutants are frequently detected in water environment. As an electrochemical advanced oxidation technology, the electro-Fenton technology generates strong oxidizing hydroxyl radicals (·OH) through the Fenton reaction between hydrogen peroxide (H2O2) and divalent iron (Fe(II)) driven by electrochemistry, and is more and more studied and used in the field of oxidation removal of new pollutants in water and wastewater treatment. However, the reaction rate of the technology is limited by the valence state cycle of Fe(II) / Fe(III), and at the same time, the dissolved metal ions are easy to produce iron-containing sludge, causing secondary pollution.

[0003] In order to improve the problems in the electro-Fenton technology and improve the degradation rate of pollutants, a water and wastewater treatment method based on 3-electron electrocatalytic oxygen reduction is proposed. In the method, oxygen first undergoes 2-electron reaction on the electrocatalytic material to generate H2O2 in situ, and further undergoes 1-electron reduction on the surface of the catalyst to generate ·OH. The process can generate ·OH without relying on the Fenton reaction, which can effectively overcome the slow limitation of the valence state cycle rate between Fe(II) / Fe(III), and effectively improve the generation rate of ·OH and the removal efficiency of pollutants.

[0004] However, the 3-electron oxygen reduction electrocatalytic materials reported at present have problems such as low catalyst activity and difficult recovery. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an iron-cobalt bimetallic anchored porous carbon electrode with high 3-electron oxygen reduction activity.

[0006] The purpose of the present application is also to provide a preparation method of the iron-cobalt bimetallic anchored porous carbon electrode.

[0007] In order to solve the above technical problems, the present application adopts the following technical scheme:

[0008] The iron-cobalt bimetallic anchored porous carbon electrode according to the first aspect of the present application has a cobalt loading of 0.5-2.5wt%, and an iron loading of 0.1-2.5wt%.

[0009] The preparation method of the iron-cobalt bimetallic anchored porous carbon electrode according to the second aspect of the present application comprises the following steps:

[0010] Step S1, providing a cobalt atom anchored carbon electrode;

[0011] Step S2, the cobalt atom-anchored carbon electrode is subjected to heat treatment after acid etching, to obtain a cobalt atom-anchored porous carbon electrode;

[0012] Step S3, the cobalt atom-anchored porous carbon electrode is immersed in an iron precursor solution, and then taken out for heat treatment, to obtain an iron-cobalt bimetallic-anchored porous carbon electrode.

[0013] Further, the step S1 comprises:

[0014] Step S11, a precursor dispersion liquid is provided, wherein a cobalt precursor and carbon particles are dispersed in the precursor solution;

[0015] Step S12, a carbon matrix is immersed in the precursor dispersion liquid, so as to adsorb the cobalt precursor and carbon particles on the surface of the carbon matrix;

[0016] Step S13, the carbon matrix adsorbed with the carbon particles and cobalt precursor is calcined in an inert gas atmosphere, to obtain the cobalt atom-anchored carbon electrode.

[0017] Further, the step S11 comprises:

[0018] The zinc precursor, dimethylimidazole, and cobalt precursor are dispersed in an organic solvent, and carbon particles are added and mixed, to obtain the precursor dispersion liquid.

[0019] Further, the step S11 comprises:

[0020] S111, the zinc precursor and dimethylimidazole are dispersed in an organic solvent, to obtain the zeolitic imidazolate framework-8 precursor solution;

[0021] S112, the zinc precursor and cobalt precursor are dispersed in the organic solvent, to obtain the cobalt precursor solution;

[0022] S113, the zeolitic imidazolate framework-8 precursor solution, the cobalt precursor solution, and the carbon particles are mixed, to obtain the precursor dispersion liquid.

[0023] Further, step S113 comprises:

[0024] The zeolitic imidazolate framework-8 precursor solution is mixed with the cobalt precursor solution;

[0025] Afterwards, the carbon particles are added into the solution and stirred at 100-150℃ for 12-36 hours to obtain the precursor dispersion, wherein the molar ratio of cobalt atoms to zinc atoms in the cobalt precursor solution is (1-1.5):(7-10), the molar ratio of nitrogen atoms to zinc atoms in the zeolitic imidazolate framework-8 precursor solution is 1:(4-6), the mass percentage of the carbon particles in the precursor dispersion is 0.6-1%, and the mass ratio of the carbon particles to the dimethyl imidazole is (0.08-0.1):1.

[0026] Further, the zinc precursor includes one or more of zinc acetate, zinc nitrate, and hydrates thereof,

[0027] The cobalt precursor includes one or more of cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt chloride, and cobalt acetylacetonate,

[0028] The carbon particles include one or more of carbon black, carbon nanotubes, and graphene,

[0029] The carbon matrix includes any one of carbon felt, carbon cloth, and carbon fiber.

[0030] Further, in the step S2, the cobalt atom-anchored carbon electrode is etched in an acid solution for 2-6 hours, and the etched cobalt atom-anchored carbon electrode is placed in a tube furnace and heated at 800-1000℃ for 2-4 hours under the protection of argon to obtain the cobalt atom-anchored porous carbon electrode.

[0031] Further, the step S3 includes:

[0032] Step S31, providing an iron precursor solution;

[0033] Step S32, immersing the cobalt atom-anchored porous carbon electrode in the iron precursor solution to impregnate the iron precursor in the micropores of the cobalt atom-anchored porous carbon electrode;

[0034] Step S33, calcining the cobalt atom-anchored porous carbon electrode impregnated with the iron precursor in air at 200-300℃ for 1-3 hours to obtain the iron-cobalt bimetallic-anchored porous carbon electrode,

[0035] The iron precursor solution contains the iron precursor, which is selected from at least one of phthalocyanine iron, iron nitrate, iron sulfate, iron chloride, and acetylacetonate iron.

[0036] Further, the iron precursor solution also contains a nitrogen-containing organic compound, which is dicyandiamide, and the step S31 includes:

[0037] The iron precursor and dicyandiamide are added to a mixed solution of ethanol and deionized water, stirred uniformly to obtain the iron precursor solution, wherein the molar ratio of the iron precursor to the dicyandiamide in the iron precursor solution is 1:(10-20).

[0038] The above technical solutions of the present application have at least one of the following beneficial effects:

[0039] The iron-cobalt bimetal-anchored porous carbon electrode according to the embodiment of the present application, on the one hand, improves the electrocatalytic activity of 3-electron oxygen reduction through the synergistic effect of iron-cobalt bimetal, and simultaneously triggers the selective electrocatalytic reduction of O2 and H2O2 to ·OH without Fenton reaction; on the other hand, active sites are directly formed on the porous carbon electrode, and the electrode can be directly used for water treatment, solving the problem of difficult recovery of electrocatalysts. In addition, the iron-cobalt bimetal is anchored inside the catalyst, which can effectively avoid contact reaction with the external solution and reduce the dissolution of metal ions, thereby providing a more efficient and green technical option for the removal of new pollutants in water and wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The flowchart of the preparation method of the iron-cobalt bimetal-anchored porous carbon electrode according to the embodiment of the present application is shown in Figure 1.

[0041] Figure 2 The curve graph of treatment time-removal rate of the carbon electrode of Example 1, Comparative Example 1 and Comparative Example 2 for treating gemfibrozil is shown in Figure 2.

[0042] Figure 3 The curve graph of treatment time-removal rate of the iron-cobalt bimetal-anchored porous carbon electrode of Example 1 for treating different target pollutants is shown in Figure 3. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0044] The preparation method of the iron-cobalt bimetal-anchored porous carbon electrode according to the embodiment of the present application will be described in detail below in combination with the drawings.

[0045] It should be noted that the source of the raw materials not mentioned in the present application can be commercially available or prepared by conventional methods, and the present application does not limit this.

[0046] Figure 1A flow chart showing a preparation method of the iron-cobalt bimetallic anchored porous carbon electrode according to an embodiment of the present application is shown.

[0047] As shown in Figure 1 The preparation method of the iron-cobalt bimetallic anchored porous carbon electrode according to an embodiment of the present application can include the following steps:

[0048] Step S1, providing a cobalt atom anchored carbon electrode;

[0049] Step S2, heat treating the cobalt atom anchored carbon electrode after acid etching to obtain a cobalt atom anchored porous carbon electrode;

[0050] Step S3, immersing the cobalt atom anchored porous carbon electrode in a iron precursor solution and heat treating to obtain an iron-cobalt bimetallic anchored porous carbon electrode.

[0051] Specifically, the preparation method of the iron-cobalt bimetallic anchored porous carbon electrode according to an embodiment of the present application, for the cobalt atom anchored carbon electrode, first performs a poration treatment, and then anchors a iron source in the pores to obtain an iron-cobalt bimetallic anchored porous carbon electrode. The iron-cobalt bimetallic anchored porous carbon electrode prepared according to an embodiment of the present application can significantly improve the electrocatalytic activity of 3-electron oxygen reduction through the synergistic effect of the iron-cobalt bimetallic, simultaneously triggers the selective electrocatalytic reduction of O2 and H2O2 to ·OH without the need for a Fenton reaction; on the other hand, active sites are formed directly on the porous carbon electrode, and the electrode can be directly used for water treatment, solving the problem of difficult recovery of electrocatalysts. In addition, the iron-cobalt bimetallic is anchored inside the catalyst, which can effectively avoid contact reactions with the external solution and reduce the dissolution of metal ions, thereby providing a more efficient and green technical choice for the removal of new pollutants in water and wastewater.

[0052] In some embodiments, either a commercially available cobalt atom anchored carbon electrode can be directly used, or the preparation method can be performed as follows, that is, step S1 can include the following steps:

[0053] Step S11, providing a precursor dispersion liquid, the precursor solution dispersing cobalt precursors and carbon particles.

[0054] Step S12, immersing the carbon matrix in the precursor dispersion liquid to adsorb cobalt precursors and carbon particles on the surface of the carbon matrix;

[0055] Step S13, calcining the carbon matrix adsorbed with carbon particles and cobalt precursors in an inert gas atmosphere to obtain a cobalt atom anchored carbon electrode.

[0056] That is, in order to prepare the cobalt atom anchoring carbon electrode, first, a precursor dispersion liquid in which cobalt precursors and carbon particles are dispersed is configured, second, the carbon matrix is immersed for adsorption, and finally, through calcination, the cobalt precursors are converted into cobalt and are simultaneously anchored on the carbon particles. Here, it needs to be pointed out that the addition of carbon particles can make the performance of the electrode more superior, because the carbon particles have high conductivity, and at the same time, it is also helpful to ensure that the electrochemical oxygen reduction reaction can occur on the electrode.

[0057] In addition, it also needs to be pointed out that the carbon particles themselves are both the main body of the reaction and the carrier of the catalyst active component. On the one hand, the carbon particles have the effects of conducting electricity and 2-electron oxygen reduction to generate hydrogen peroxide, and on the other hand, through the previous calcination molding (and subsequent heat treatment process), some micropores are formed on the carbon particles, which are convenient for the anchoring of cobalt and iron. In this way, oxygen first undergoes a 2-electron oxygen reduction reaction on the surface of the carbon particles, and then through the electron conduction effect of the carbon particles itself, the third electron is transferred to iron and cobalt to undergo a three-electron oxygen reduction; and the anchoring of iron and cobalt on the micropores of the carbon particles helps to reduce their exposure and precipitation in the solution. In comparison, directly anchoring the catalyst on the carbon base material directly exposes the iron and cobalt components to the outside, which is easy to lead to the dissolution of metal ions and produce a large amount of secondary pollution after the reaction.

[0058] In some embodiments, the step S11 comprises:

[0059] The zinc precursor, dimethylimidazole and cobalt precursor are dispersed in an organic solvent, and carbon particles are added and mixed to obtain the precursor dispersion liquid.

[0060] That is, dimethylimidazole is used as a nitrogen source, and after subsequent heat treatment, a nitrogen-doped carbon electrode can be formed. Nitrogen doping can change the electronic structure and chemical properties of carbon materials, thereby improving their electrochemical performance. In addition, the doping of nitrogen atoms can introduce additional charges, increase the conductivity of carbon materials, and also adjust the surface properties of carbon materials, increase their interaction with electrolyte, and improve the catalytic activity.

[0061] In addition, by introducing nitrogen at the same time as introducing cobalt, the cobalt is anchored on the carbon particles in the form of Co-N structure, forming a Co-N-C structure, that is, using nitrogen as a transition, so that the cobalt can be more firmly anchored on the surface of the carbon particles.

[0062] By introducing nitrogen in the embodiments of the present application, the physical and chemical properties, the acid-base degree and the wettability of the catalyst can be improved, and the catalytic performance can be improved by synergistic effect with iron and cobalt.

[0063] In addition, since the sizes of nitrogen atoms and carbon atoms are similar, the destruction of the carbon material skeleton structure is small during the substitution of carbon atoms by nitrogen atoms, and the stability of the carbon material can be maintained. On this basis, since nitrogen atoms are more electronegative than carbon atoms, the doped carbon material has more excellent electronic conductivity. In other embodiments, step S11 specifically includes:

[0064] S111, dispersing the zinc precursor and dimethyl imidazole in an organic solvent to obtain a zeolitic imidazolate framework-8 (ZIF-8 precursor) precursor solution.

[0065] Specifically, the zinc precursor is coordinated with dimethyl imidazole to form a super-small molecular sieve imidazolate framework ZIF-8 precursor.

[0066] S112, dispersing the zinc precursor and the cobalt precursor in an organic solvent to obtain a cobalt precursor solution.

[0067] By adding Zn 2+ in the cobalt precursor solution, a competitive coordination strategy is introduced, which can hinder the coordination of Fe 2+ subsequently added, thereby promoting the effective dispersion of Fe.

[0068] Here, it should be noted that the zinc precursor can also be introduced only once in step S111.

[0069] S113, mixing the zeolitic imidazolate framework-8 precursor solution, the cobalt precursor solution, and the carbon particles to obtain a precursor dispersion. In some embodiments, the zinc precursor includes one or more of zinc acetate, zinc nitrate, and hydrates thereof.

[0070] The cobalt precursor includes one or more of cobalt nitrate, cobalt sulfate, cobalt acetate, and cobalt chloride. These cobalt precursors have good stability and good solubility.

[0071] The carbon particles include one or more of carbon black, carbon nanotubes, and graphene. These carbon particles have conductivity and help 2-electron oxygen reduction, promoting 3-electron redox reactions on the electrode.

[0072] The carbon matrix includes any one of carbon felt, carbon cloth, and carbon fiber.

[0073] In some embodiments of the present application, the carbon matrix material is carbon felt, which not only integrates concentration, adsorption, reduction, and separation of active carbon fibers, but also has large adsorption capacity, high recovery rate, and good selectivity. The porosity of the porous carbon electrode is determined by the purchased carbon felt base material. The thickness of the carbon felt is 0.1-30 mm, and the porosity of the carbon felt is 70%-99%, preferably 85%-99%.

[0074] In addition, the carbon felt can be subjected to impurity removal treatment first, for example, the carbon felt is sequentially washed with ethanol and deionized water in ultrasonic baths, and then is annealed at 400 DEG C for 4 hours to remove surface oil stains and other impurities.

[0075] In some embodiments, step S113 comprises:

[0076] mixing the zeolitic imidazolate framework-8 precursor solution with the cobalt precursor solution;

[0077] Thereafter, carbon particles are added and stirred at 100-150 DEG C for 12-36 hours to obtain a precursor dispersion.

[0078] Through continuous stirring at 100-150 DEG C for 12-36 hours, cobalt-nitrogen atom-doped nanocrystals can grow on the surface of the carbon particles, thereby being anchored on the carbon particles in a Co-N-C structure. When the particle size is at the nanometer level, the cobalt atom-anchored carbon electrode can have a higher specific surface area in the subsequent process, which can bring a larger contact area, so that the cobalt atom-anchored carbon electrode prepared has a faster electron conduction rate and a higher cobalt ion activity.

[0079] In some embodiments, the molar ratio of cobalt atoms to zinc atoms in the cobalt precursor solution is (1-1.5):(7-10), the molar ratio of nitrogen atoms to zinc atoms in the zeolitic imidazolate framework-8 precursor solution is 1:(4-6), and the mass percentage of the carbon particles in the cobalt precursor dispersion is 0.6-1%. The mass ratio of the carbon particles to dimethylimidazole is (0.08-0.1):1. That is, a stoichiometric ratio can be referred to, and an appropriate amount of zinc can be introduced to improve the uniformity of iron dispersion through a competitive coordination strategy.

[0080] In addition, it should be noted that in some embodiments of the present application, the product exists in the form of iron-cobalt bimetal, which can directly activate hydrogen peroxide as a whole, and the protection of the carbon matrix further makes it less susceptible to solution pH, thereby ensuring a wider pH application range, overcoming the disadvantages of narrow pH application range of traditional homogeneous Fenton technology and slow transition metal circulation rate of heterogeneous Fenton technology, and efficiently degrading organic pollutants in water under conventional water treatment conditions (pH = 6.5-8.5).

[0081] As described above, after obtaining the cobalt atom-anchored carbon electrode, it is subjected to a poration treatment. In some embodiments of the present application, the poration treatment (i.e., step S2) can specifically comprise:

[0082] The cobalt atom-anchored carbon electrode is acid-etched in an acid solution for 2-6 hours, and the acid-etched cobalt atom-anchored carbon electrode is placed in a tube furnace and heated at 800-1000℃ for 2-4 hours under the protection of argon. The protection of argon can avoid the oxidation of cobalt and carbon. In some embodiments, the acid solution can be sulfuric acid, which can etch microporous holes and remove some cobalt metal clusters that are not fully dispersed.

[0083] Further, after the acid etching treatment, the acid-etched cobalt atom-anchored carbon electrode can be dried in a vacuum oven at 40-60℃ for 2-4 hours to remove the solvent therein.

[0084] The cobalt atom-anchored porous carbon electrode obtained as described above can be further subjected to iron anchoring to obtain an iron-cobalt bimetallic-anchored porous carbon electrode. In some embodiments of the present application, the step of iron anchoring (i.e., step S3) can include:

[0085] Step S31, providing an iron precursor solution.

[0086] The iron precursor solution contains an iron precursor selected from at least one of iron phthalocyanine, ferric nitrate, ferric sulfate, ferric chloride and acetylacetone iron.

[0087] In some embodiments, the iron precursor solution further contains a nitrogen-containing organic compound, and the nitrogen-containing organic compound is dicyandiamide. Step S31 includes:

[0088] The iron precursor and dicyandiamide are added to a mixed solution of ethanol and deionized water, and stirred uniformly to obtain the iron precursor solution, wherein the molar ratio of the iron precursor to dicyandiamide in the iron precursor solution is 1:(10-20).

[0089] Here, it should be noted that the second addition of the nitrogen source dicyandiamide is to effectively introduce more FeN4 active sites in the catalyst. The formed FeN4 structure can be effectively stabilized in the carbon particle skeleton, and can efficiently decompose hydrogen peroxide to form an O=FeN4=O active center.

[0090] Step S32, immersing the cobalt atom-anchored porous carbon electrode in the iron precursor solution to impregnate the iron precursor in the micropores of the cobalt atom-anchored porous carbon electrode;

[0091] Step S33, calcining the cobalt atom-anchored porous carbon electrode impregnated with the iron precursor in air at 200-300℃ for 1-3 hours to obtain an iron-cobalt bimetallic-anchored porous carbon electrode.

[0092] The specific process and principle of impregnating the microporous carbon electrode with iron precursor to anchor cobalt atoms in the micropores of the carbon electrode, and heat-treating to convert the iron precursor and nitrogen precursor, are substantially the same as the cobalt atom anchoring and nitrogen doping, and will not be described in detail herein.

[0093] In some embodiments of the present application, simple acid washing, water washing, and drying can be further performed after the heat treatment in step S2 and step S3, respectively. Through the acid washing step, cobalt and iron that are not firmly anchored can be washed off. There is no special limitation on the specific acid, which can be, for example, hydrochloric acid, dilute sulfuric acid, or other commonly used acids.

[0094] Through the preparation method described above and by adjusting the ratio of each raw material, the iron-cobalt bimetallic anchored porous carbon electrode can be obtained, in which the loading amount of cobalt can be 0.5-2.5wt%, and the loading amount of iron can be 0.1-2.5wt%.

[0095] The preparation method of the iron-cobalt bimetallic anchored porous carbon electrode of the present application will be further described below through examples.

[0096] Example 1

[0097] 1) Preparation of cobalt atom anchored carbon electrode

[0098] 1.1) Preparation of precursor dispersion solution:

[0099] 1g of dimethylimidazole and 2g (9.112mmol) of zinc acetate dihydrate solution were weighed and dissolved in 10mL of N-N dimethylformamide solvent to obtain solution A;

[0100] 1g (3.44mmol) of cobalt nitrate hexahydrate and 8g (36.448mmol) of zinc acetate dihydrate solution were weighed and dissolved in 10mL of N-N dimethylformamide solvent to obtain solution B;

[0101] Solution A and solution B were mixed, and 80mg of carbon black was added to the above solution. The mixture was continuously stirred at 120℃ for 24h to form a precursor dispersion solution.

[0102] 1.2) Impregnation: The carbon felt was sequentially washed with ethanol and deionized water in an ultrasonic bath for 30min, and then annealed at 400℃ for 4h to remove impurities. The pretreated carbon felt was immersed in the precursor solution prepared in step 1.1) for 3h, and then completely dried in a vacuum oven at 45℃.

[0103] 1.3) Calcination: The impregnated and dried carbon felt was placed in a tube furnace and heated at 1000℃ for 1h under argon protection, and then naturally cooled to room temperature to obtain a cobalt atom anchored carbon electrode.

[0104] 2) Preparation of cobalt atom-anchored porous carbon electrode

[0105] The material obtained in step 1.3) was placed in a 0.5 mol / L H2SO4 solution for acid etching for 4 hours. The acid-etched material was then placed in a tube furnace and heated at 900°C for 3 hours under argon protection to obtain a cobalt atom-anchored porous carbon electrode.

[0106] 3) Preparation of iron-cobalt bimetallic anchored porous carbon electrode

[0107] 0.085 g of iron phthalocyanine (3 mmol) and 0.1261 g of dicyandiamide (30 mmol) were added to 50 mL of a mixed solution of ethanol and deionized water (1:1). After stirring for 30 min, a homogeneous solution was obtained. The porous carbon electrode prepared in step 2) was placed in the above homogeneous solution and allowed to stand for 4 h. After being removed, it was dried in a vacuum oven at 60 °C for 5 h, and then calcined at 250 °C for 2 h. After cooling to room temperature, a porous carbon electrode anchored by iron-cobalt bimetallic structure for 3-electron oxygen reduction was obtained.

[0108] Comparative Example 1:

[0109] Except for not performing the iron anchoring treatment in step 3) after step 2), the process is the same as in Example 1 above, resulting in a cobalt monometallic anchored porous carbon electrode.

[0110] Comparative Example 2:

[0111] Referring to Example 1 above, except that in step 1), iron phthalocyanine is used instead of cobalt nitrate, and the process ends after step 2), the rest is the same as in the above example, to obtain an iron monometallic anchored porous carbon electrode.

[0112] Performance test experiment A: Treatment effect of gemfibrozil solution

[0113] The water sample to be treated was a 10 mg / L gemfibrozil solution, the electrolyte was 0.05 M sodium sulfate, the pH of the solution was maintained at 6.5 using a 5 mM phosphate buffer solution, the volume of the water sample to be treated was 100 mL, and the oxygen inlet flow rate was 0.15 L / min.

[0114] The anode is a titanium-plated platinum electrode, and the cathodes are the electrodes prepared in Example 1, Comparative Example 1, and Comparative Example 2, respectively. The electrode area is 4×5cm. 2 The current applied to the anode and cathode is 60mA, which is equivalent to a current density of 3mA / cm². 2 The water sample to be treated was subjected to electrolytic treatment.

[0115] like Figure 2 As shown, when the iron-cobalt bimetallic anchored porous carbon prepared according to Example 1 is subjected to electrocatalytic treatment, the removal rate of gemfibrozil can reach more than 95% when the treatment time is 5 minutes.

[0116] Compared with the experimental results of the titanium plating platinum electrode and the cobalt single metal anchoring porous carbon electrode (comparative example 1) under the same experimental conditions except that the anode and cathode were titanium plating platinum electrodes, the removal rate was increased by about 40% in 15 minutes; compared with the experimental results of the titanium plating platinum electrode and the iron single metal anchoring porous carbon electrode (comparative example 2) under the same experimental conditions except that the anode and cathode were titanium plating platinum electrodes, the removal rate was increased by about 20% in 15 minutes.

[0117] Performance test experiment B treatment effect of other solutions

[0118] The pollutants were changed to ciprofloxacin, alachlor, chloramphenicol and sulfamethoxazole, respectively, to detect the broad-spectrum performance of the iron-cobalt bimetallic anchoring porous carbon electrode in application in example 1.

[0119] The experimental results are shown in Table 1. Figure 3 The efficient degradation of different pollutants was achieved in 15 minutes, and the degradation rates were 97%, 85%, 75% and 98% in 15 minutes, respectively. It shows that the catalyst has excellent removal performance for various refractory organic matters in water.

[0120] Example 2

[0121] Except for the following scheme, it is the same as example 1: in step 2), the carbon felt is placed in a tube furnace and heated at 800°C for 2h under argon protection; the obtained iron-cobalt bimetallic anchoring porous carbon electrode. According to the operation mode in the above performance evaluation, the wastewater treatment is carried out, and the removal rate of gemfibrozil is 85.85% after 15 minutes.

[0122] Example 3

[0123] Except for the following differences, it is the same as example 1: in step 2), the carbon felt is placed in a tube furnace and heated at 1000°C for 2h under argon protection; the obtained iron-cobalt bimetallic anchoring porous carbon electrode. According to the operation mode in the above performance evaluation, the wastewater treatment is carried out, and the removal rate of gemfibrozil is 92.76% after 15 minutes.

[0124] Example 4

[0125] Except for the following differences, it is the same as example 1: in step 3), the cobalt atom anchoring porous carbon electrode containing the iron precursor is calcined at 200°C in air for 2h; the obtained iron-cobalt bimetallic anchoring porous carbon electrode, according to the operation mode of example 2, the removal rate of gemfibrozil is 88.85% after 15 minutes.

[0126] Example 5

[0127] The same as Example 1 except that in step 3), the cobalt atom-anchored porous carbon electrode impregnated with iron precursor was calcined at 300℃ in air for 2h, respectively; the obtained iron-cobalt bimetallic-anchored porous carbon electrode.

[0128] The wastewater was treated according to the operation mode in the above performance evaluation, and the removal rate of gemfibrozil was 98.45% after 15 minutes.

[0129] Example 6

[0130] The same as Example 1 except that in step 1.1), 1.5g of cobalt nitrate hexahydrate and 7g of zinc nitrate hexahydrate were weighed; the obtained iron-cobalt bimetallic-anchored porous carbon electrode.

[0131] The wastewater was treated according to the operation mode in the above performance evaluation, and the removal rate of gemfibrozil was 90.85% after 15 minutes.

[0132] Example 7

[0133] The same as Example 1 except that in step 1.1), 100mg of carbon black was weighed and dispersed into the mixed solution; the obtained iron-cobalt bimetallic-anchored porous carbon electrode.

[0134] The wastewater was treated according to the operation mode in the above performance evaluation, and the removal rate of gemfibrozil was 96.58% after 15 minutes.

[0135] Example 8

[0136] The same as Example 1 except that in step 3), 1.705g of iron phthalocyanine (3mmol) and 2.522g of dicyanamide (45mmol) and 1.705g of iron phthalocyanine (3mmol) and 2.522g of dicyanamide (60mmol) were weighed and added into the mixed solution of ethanol and deionized water; the obtained iron-cobalt bimetallic-anchored porous carbon electrode.

[0137] The wastewater was treated according to the operation mode in the above performance evaluation, and the removal rate of gemfibrozil was 93.10% and 95.92% after 15 minutes, respectively.

[0138] Example 9

[0139] The same as Example 1 except that in step 1.1),

[0140] 1g of dimethylimidazole, 10g (9.112mmol) of zinc acetate dihydrate solution, and 1g (3.44mmol) of cobalt nitrate hexahydrate were weighed and dissolved in 20mL of N-N dimethylformamide solvent to obtain a mixed solution;

[0141] Then, 80 mg of carbon black was added to the mixed solution, and the mixture was continuously stirred at 120°C for 24 hours to form a precursor dispersion liquid.

[0142] The wastewater was treated according to the operation mode in the above performance evaluation, and the removal rate of gemfibrozil was 94.70% after 15 minutes.

[0143] The above describes the preferred embodiments of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing an iron-cobalt bimetallic anchored porous carbon electrode, characterized in that, The method comprises the following steps: Step S1, providing a cobalt atom anchoring carbon electrode; Step S2, heat treating the cobalt atom anchoring carbon electrode after acid etching to obtain a cobalt atom anchoring porous carbon electrode; Step S3, immersing the cobalt atom anchoring porous carbon electrode in an iron precursor solution, and then taking it out for heat treatment to obtain an iron-cobalt bimetal anchoring porous carbon electrode; The step S1 comprises: Step S11, providing a precursor dispersion liquid, wherein the precursor solution is dispersed with cobalt precursor and carbon particles, and the step S11 comprises: dispersing zinc precursor, dimethyl imidazole and cobalt precursor in an organic solvent, and adding carbon particles therein for mixing to obtain the precursor dispersion liquid; Step S12, immersing a carbon matrix in the precursor dispersion liquid to adsorb the cobalt precursor and carbon particles on the surface of the carbon matrix; Step S13, calcining the carbon matrix adsorbed with the carbon particles and cobalt precursor in an inert gas atmosphere to obtain the cobalt atom anchoring carbon electrode; The step S3 comprises: Step S31, providing an iron precursor solution, wherein the iron precursor solution contains iron precursor and nitrogen-containing organic matter, and the nitrogen-containing organic matter is dicyandiamide, and the step S31 comprises: adding the iron precursor and dicyandiamide into a mixed solution of ethanol and deionized water, and stirring uniformly to obtain the iron precursor solution; Step S32, immersing the cobalt atom anchoring porous carbon electrode in the iron precursor solution to impregnate the iron precursor in the micropores of the cobalt atom anchoring porous carbon electrode; Step S33, calcining the cobalt atom anchoring porous carbon electrode impregnated with the iron precursor in air at 200-300 DEG C for 1-3 hours to obtain the iron-cobalt bimetal anchoring porous carbon electrode.

2. The production method according to claim 1, characterized by, The step S11 comprises: S111, dispersing zinc precursor and dimethyl imidazole in an organic solvent to obtain a zeolite imidazole framework-8 precursor solution; S112, dispersing zinc precursor and cobalt precursor in the organic solvent to obtain a cobalt precursor solution; S113, mixing the zeolite imidazole framework-8 precursor solution, the cobalt precursor solution, and the carbon particles to obtain the precursor dispersion liquid.

3. The preparation method according to claim 2, characterized in that, Step S113 comprises: Mixing the zeolite imidazole framework-8 precursor solution with the cobalt precursor solution; Then, adding the carbon particles therein, and stirring uniformly at 100-150 DEG C for 12-36 hours to obtain the precursor dispersion liquid, Wherein, the molar ratio of cobalt atoms to zinc atoms in the cobalt precursor solution is (1-1.5):(7-10), the molar ratio of nitrogen atoms to zinc atoms in the zeolite imidazole framework-8 precursor solution is 1:(4-6), the mass percentage of the carbon particles in the precursor dispersion liquid is 0.6-1%, and the mass ratio of the carbon particles to the dimethyl imidazole is (0.08-0.1):

1.

4. The preparation method according to claim 1 or 2, wherein The zinc precursor comprises one or more of zinc acetate, zinc nitrate, and hydrates thereof, The cobalt precursor includes one or more of cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt chloride, and cobalt acetylacetonate, The carbon particles include one or more of carbon black, carbon nanotubes, and graphene, The carbon matrix includes any one of carbon felt, carbon cloth, and carbon fiber.

5. The preparation method according to claim 1, characterized in that, In the step S2, the cobalt atom-anchored carbon electrode is acid-etched in an acid solution for 2-6 hours, and the acid-etched cobalt atom-anchored carbon electrode is placed in a tube furnace and heated at 800-1000℃ for 2-4 hours under the protection of argon to obtain the cobalt atom-anchored porous carbon electrode.

6. The preparation method of claim 1, wherein, The iron precursor is selected from at least one of iron phthalocyanine, iron nitrate, iron sulfate, iron chloride, and iron acetylacetonate.

7. The preparation method according to claim 1, characterized in that, The molar ratio of the iron precursor to the dicyandiamide in the iron precursor solution is 1:(10-20).

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