A layered porous self-supporting biomass carbon-based composite electrode material and its preparation method and application

Abstract

A layered porous self-supporting biomass carbon-based composite electrode material and its preparation method and application belong to the field of three-electrode catalytic oxidation. The method is as follows: disposable poplar chopsticks are cut into 3mm thick long wood pieces, and N-doped self-supporting carbonized wood coated with a certain proportion of Fe and Co transition metals is constructed by impregnation and high-temperature calcination; the carbonized wood after high-temperature treatment is subjected to a constant current deposition method to uniformly grow Fe-CoP in situ on the N-doped carbonized wood coated with a certain proportion of Fe and Co transition metals, construct a heterogeneous structure of carbon layer alloy and phosphide, and prepare a transition metal phosphide / layered porous biomass carbon-based electrode material. The layered porous self-supporting biomass carbon-based composite electrode material prepared by the present invention can provide more active sites, increase the yield of hydroxyl radicals to more efficiently perform electrocatalytic oxidation and degradation of antibiotics in water, and has good structural stability, excellent conductivity, and excellent pollutant degradation efficiency.

Description

Technical Field

[0001] The present invention relates to a three-electrode catalytic system, and in particular to a layered porous self-supporting biomass carbon-based composite electrode material, a preparation method thereof, and an application thereof. Background Art

[0002] Antibiotics effectively prevent and treat bacterial infections, making them indispensable to human health. Their low cost and broad-spectrum antibacterial properties have led to their widespread use. Tetracyclines are among the most widely used and consumed antibiotics. However, due to their non-biodegradability, their release into aquatic environments can induce the development of drug-resistant bacteria, exacerbating water pollution. Even in trace amounts, drug-resistant bacteria in the natural environment can cause significant damage to human health and aquatic ecosystems. Therefore, a process technology that is simple, efficient, cost-effective, and less toxic must be developed to address the tetracycline pollution problem.

[0003] Electrocatalytic oxidation is a technology with strong ability to degrade organic pollutants. It can produce hydroxyl radicals (·OH) under electrochemical action. Therefore, compared with traditional oxidation methods, this method can more thoroughly oxidize and degrade pollutants. It can also treat a wide range of organic pollutants and has good research and application prospects.

[0004] In the field of electrocatalysis, precious metal oxides such as platinum and ruthenium are often used as standard high-performance catalysts. However, their high cost, extreme scarcity, and poor stability hinder their large-scale practical application. To address these current problems, transition metal materials, as non-precious metal catalysts, possess excellent electrocatalytic properties and have become an effective alternative to precious metal-based materials to improve electrooxidation performance.

[0005] Recently, dual transition metal FeCo alloys and transition metal phosphides have attracted widespread attention due to their low cost and high activity. Studies have shown that doping with a certain amount of metallic iron can effectively modulate the electronic structure of the metallic cobalt center by inducing charge transfer, increasing the material's conductivity, providing more active sites, and effectively improving electrooxidation performance. However, simple FeCo alloy catalysts show low electrooxidation activity, while transition metal phosphides are prone to agglomeration, have poor conductivity, and have strong oxygen evolution ability, which limit their application in the field of electrooxidation.

[0006] To enhance the catalytic activity of bimetallic catalysts, transition metal phosphides and FeCo alloys are often combined with porous conductive substrates to create self-supporting electrodes with improved performance, often by constructing appropriate heterostructures and adjusting the electronic structure of the alloy. Porous carbon materials, typically used as substrates, possess excellent electrical conductivity. Doping carbon supports with atoms such as nitrogen, sulfur, and phosphorus can enhance their electrochemical properties. These atoms are highly electronegative, leading to charge distribution between adjacent carbon atoms and promoting water decomposition. In particular, nitrogen-doped carbon materials exhibit excellent electrical conductivity and a high degree of graphitization, which facilitates the electrooxidative degradation of pollutants.

[0007] The carbon materials currently used for electrocatalytic oxidation, such as diamond, graphite, porous carbon, graphene, carbon nanotubes, etc., have excellent structural properties and degradation efficiency, but their application is limited due to their high cost. They also have disadvantages such as complex production processes and difficulty in large-scale synthesis. Summary of the Invention

[0008] The purpose of the present invention is to solve the problems that the application of precious metal catalysts and carbon materials currently used for electrocatalytic oxidation is limited due to their high cost, and there are also problems such as complex production processes and difficulties in large-scale synthesis. A method for preparing a layered porous self-supporting biomass carbon-based composite electrode material is provided. The method uses disposable poplar chopsticks as raw materials, and a certain proportion of Fe and Co binary nanoparticles are coated on the N-doped wood biomass carbon base through a simple impregnation-high-temperature calcination-constant current deposition method, and a transition metal phosphide is constructed to form a heterogeneous structure of a bimetallic alloy and a transition phosphide, thereby preparing a layered porous biomass carbon-based composite electrode FeCoP / FeCo@NCW, which can achieve excellent performance in electro-oxidation degradation of organic pollutants.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing a layered porous self-supporting biomass carbon-based composite electrode material, the method comprising the following steps:

[0011] S1: Cut waste disposable wood products into long wood chips 2-4 mm thick. Through impregnation and high-temperature calcination, N-doped self-supporting carbonized wood FeCo@NCW coated with a certain proportion of Fe and Co transition metals is constructed;

[0012] S2: N-doped self-supporting carbonized wood FeCo@NCW coated with a certain proportion of Fe and Co transition metals is subjected to constant current electrodeposition to uniformly grow Fe-Co-P on the carbonized wood in situ to prepare a transition metal phosphide / hierarchical porous self-supporting biomass carbon-based composite electrode material.

[0013] Furthermore, the step S1 includes:

[0014] S11: Cut a piece of disposable wood product into long wood chips 2 to 4 mm thick, immerse the wood chips in an ethanol solution containing Fe(NO3)3·9H2O, Co(NO3)2·6H2O, and dicyandiamide, place them in an oven and soak until the ethanol evaporates completely, remove the wood chips and place them in an oven to dry;

[0015] S12: The treated wood chips are placed in a tubular furnace and calcined at high temperature to obtain N-doped carbonized wood FeCo@NCW coated with a certain proportion of Fe and Co transition metals.

[0016] In order to realize the high-value utilization of disposable wood products, we initially screened out the best electrocatalytic properties of calcined poplar chopsticks from disposable poplar sticks (birch), disposable chopsticks (poplar), and disposable chopsticks (pine). By searching the literature, we found that after carbonization of birch, poplar, and pine, poplar had the best conductivity, while pine had the worst. In addition, the porous carbon of poplar had the richest pore structure, moderate pore size, and the highest porosity, which was most conducive to the electrocatalytic reaction. This was consistent with the results of the preliminary screening experiment, and discarded disposable poplar chopsticks had the best electrocatalytic properties. By impregnating wood chips with solution and utilizing the natural layered and porous structure of wood, transition metal ions entered the three-dimensional channels inside the wood chips. Under the chelation of a large number of hydroxyl groups, they were adsorbed on the cell walls of the wood chips. After high-temperature calcination, they were coated in the three-dimensional structure of the carbon layer, which enhanced the conductivity of the material, provided more active sites, and formed a self-supporting carbon-based material with excellent electrocatalytic properties. Dicyandiamide has a high nitrogen content of 11%. After high-temperature calcination, NH3 is decomposed at high temperature to form N-doped carbon materials in a tubular furnace. High N doping mainly forms three nitrogen species in the carbonized wood: pyrrolic N, pyridinic N, and graphitic N. Studies have shown that pyrrolic N and pyridinic N can participate in the generation of hydroxyl radicals, and graphitic N can increase the degree of graphitization of carbon materials and enhance conductivity. High N doping can improve the electrochemical properties of self-supporting carbon-based materials and strengthen the electrocatalytic oxidation process.

[0017] Furthermore, in step S1, the impregnation solution contains 1 g of dicyandiamide and 20 mL of ethanol.

[0018] Furthermore, the high-temperature calcination process in step S1 is as follows: the temperature is raised to 700-900°C in a nitrogen atmosphere at a rate of 5°C / min and maintained for 2 hours for pyrolysis. Research has shown that higher calcination temperatures increase the degree of graphitization of the carbon material itself, improving its conductivity and enhancing its electrocatalytic performance. However, excessively high temperatures can reduce the stability of the carbon material and destroy its three-dimensional structure. In practical testing, the wood calcination temperature was optimized to account for energy consumption.

[0019] Furthermore, the step S2 includes:

[0020] S21: FeSO4·7H2O or Fe(NO3)3·9H2O, Co(NO3)2·6H2O, NaH2PO2·H2O and NH4Cl were dissolved in deionized water to prepare an electrodeposition solution;

[0021] S22: In a standard three-electrode system, constant current (electrochemical) deposition is performed on the FeCo@NCW surface for a period of time to finally obtain the transition metal phosphide / hierarchical porous biomass carbon-based electrode material FeCoP / FeCo@NCW.

[0022] Carbonized wood retains its three-dimensional layered porous structure, providing a large number of loading sites. Using the constant current deposition method, Fe-CoP nanoparticles can be evenly dispersed and grown in situ on the carbonized wood surface, forming a heterostructure with the carbon layer FeCo alloy, adjusting the electron cloud density of the composite material. Under the synergistic effect of the good water decomposition ability of the phosphide, the strong electrochemical properties of the bimetallic alloy, and the excellent conductivity of the N-doped carbon material, the electrocatalytic oxidation performance of the composite material is greatly improved.

[0023] Furthermore, in the step S2, the molar ratio of transition metal ions in the 50 mL electrodeposition solution is the same as that in the step S1, the amount of ethanol is 20 mL; and the molar ratio of metal ions to phosphorus source is 1:2-7.

[0024] Furthermore, the electrodeposition process in step S2 is as follows: FeCo@NCW is used as the working electrode, Ag / AgCl electrode is used as the reference electrode, and Pt sheet is used as the counter electrode. By constant current electrodeposition method, the mixed solution is charged at 10 mA / cm 2 The FeCo@NCW surface was electroplated with a constant current for 10 min, and the transition metal phosphide / hierarchical porous biomass carbon-based electrode material FeCoP / FeCo@NCW was finally obtained.

[0025] A layered porous self-supporting biomass carbon-based composite electrode prepared by the above-mentioned preparation method of the layered porous self-supporting biomass carbon-based composite electrode material. The raw material of the transition metal phosphide / layered porous biomass carbon-based electrode material of the present invention is disposable chopsticks, which are widely available. Compared with existing anode materials such as diamond, graphene, and carbon nanotubes, the cost is low and the preparation method is simple, which is a high-value utilization of disposable wood products. After carbonization, it still retains the natural three-dimensional layered porous structure, which can provide a large number of loading sites, solves the problem of easy agglomeration and low stability of phosphides, and exposes more active sites. In addition, due to the excellent conductivity of the high-N doped carbon material and the good electrochemical properties of the carbon layer FeCo alloy, it improves the electrical conductivity of the phosphide material. A certain amount of Fe doping CoP adjusts the electronic structure of the phosphide, reduces the water decomposition energy barrier, and improves the ability to produce hydroxyl radical intermediates. It has excellent performance in degrading organic pollutants in the electrocatalytic oxidation system and has an excellent removal effect on antibiotics in sewage.

[0026] An application of the above-mentioned layered porous self-supporting biomass carbon-based composite electrode material in a three-electrode catalytic system, in which a platinum sheet is used as the cathode, the layered porous self-supporting biomass carbon-based composite electrode material is used as the anode, an Ag / AgCl electrode is used as the reference electrode, and Na2SO4 is used as the supporting electrolyte.

[0027] Furthermore, a three-electrode catalytic system was used to perform electrocatalytic oxidation degradation of antibiotic organic pollutants (taking tetracycline as an example); relevant electrochemical tests and organic pollutant (tetracycline TCH) degradation experiments were performed on an electrochemical workstation using a standard three-electrode system; the plate spacing in the three-electrode catalytic degradation system was 3 cm; the current density was 10 mA / cm 2 ; Pollutant concentration is 25mg / L; Electrolyte Na2SO4 concentration is 0.1moL / L.

[0028] The beneficial effects of the present invention compared to the prior art are:

[0029] (1) Carbonized wood, as a new type of self-supporting porous carbon-based material, has the characteristics of a wide range of raw material sources, low cost, and environmental friendliness. After carbonization, biomass wood still maintains a three-dimensional layered porous structure and contains functional groups such as hydroxyl groups, which can coordinate with metal catalysts, provide a large number of loading sites for the catalyst, effectively and evenly disperse nanoparticles, and thus expose more active sites. In addition, carbonized wood has good electrical conductivity, which can promote the electron transfer of the overall catalyst, thereby improving the performance of the catalyst in electro-oxidative degradation of pollutants.

[0030] (2) The raw materials of the present invention can be disposable chopsticks, which are widely available. Compared with existing anode diamond, graphene, carbon nanotubes and other materials, the cost is low and the preparation method is simple. It is a high-value utilization of disposable wood products. After carbonization, the natural three-dimensional layered porous structure is retained, which can provide a large number of loading sites, solving the problem of easy agglomeration and low stability of phosphides, and exposing more active sites. In addition, due to the excellent conductivity of the high-N doped carbon material and the good electrochemical properties of the carbon layer FeCo alloy, the conductive properties of the phosphide material are improved. A certain amount of Fe doping CoP adjusts the electronic structure of the phosphide, reduces the water decomposition energy barrier, and improves the ability to produce hydroxyl radical intermediates. It has excellent performance in degrading organic pollutants in the electrocatalytic oxidation system and has an excellent removal effect on antibiotics in sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of the preparation method of the layered porous biomass carbon-based composite electrode material in an embodiment of the present invention.

[0032] Figure 2 This is a diagram showing the mechanism model of the application of the layered porous biomass carbon-based composite electrode of the present invention in the degradation of organic pollutants (R).

[0033] Figure 3 This is an SEM image of the 10 μm layered porous biomass carbon-based composite electrode prepared in Example 1 of the present invention.

[0034] Figure 4 This is an SEM image of the 1 μm layered porous biomass carbon-based composite electrode prepared in Example 1 of the present invention.

[0035] Figure 5 XRD patterns of the layered porous biomass carbon-based composite electrodes prepared in Examples 1 and 2 of the present invention.

[0036] Figure 6 These are Raman spectra of the layered porous biomass carbon-based composite electrodes prepared in Examples 1, 3, and 4 of the present invention.

[0037] Figure 7 This is a graph showing the trend of the TCH degradation performance of the layered porous biomass carbon-based composite electrode catalytic oxidation provided by the present invention as the ratio of Fe and Co metals in different electrode materials changes.

[0038] Figure 8 This is a graph showing the trend of the TCH degradation performance of the layered porous biomass carbon-based composite electrode catalytic oxidation provided by the present invention as the calcination temperature of different electrode materials changes.

[0039] Figure 9This is a graph showing the trend of the TCH degradation performance of the layered porous biomass carbon-based composite electrode catalytic oxidation provided by the present invention as the ratio of metal ions to phosphorus sources in different electrode materials changes. DETAILED DESCRIPTION

[0040] The following provides specific examples of the present invention to further illustrate the present invention. However, the examples do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0041] Example 1

[0042] A method for preparing a layered porous biomass carbon-based composite electrode material, such as Figure 1 As shown, the specific steps include:

[0043] S11: Cut a piece of disposable poplar chopsticks into a long piece of wood with a thickness of 20mm×8mm×3mm. Immerse the wood piece in a solution containing 1mmoLFe(NO3)3·9H2O, 1mmoLCo(NO3)2·6H2O, 1g dicyandiamide and 20mL ethanol. The molar ratio of transition metal ions in the immersion solution is Fe 3+ :Co 2+ =0.5:0.5, put it in the oven and soak until the ethanol evaporates completely, take out the wood chips and put them in the oven to dry.

[0044] S12: The treated wood chips were placed in a tube furnace and heated to 800°C at a rate of 5°C / min in a N2 atmosphere and maintained for 2 hours for pyrolysis and calcination to obtain N-doped carbonized wood Fe coated with Co transition metal. 0.5 Co 0.5 @NCW.

[0045] S21: 2.5mmoLFeSO4·7H2O, 2.5mmoLCo(NO3)2·6H2O, 0.025moLNaH2PO2·H2O and 5mmoLNH4Cl were dissolved in 50mL deionized water to prepare the electrodeposition solution, in which the molar ratio of transition metal ions was Fe 2+ :Co 2+ =0.5:0.5, metal ion:phosphorus source =1:5.

[0046] S22: FeCo@NCW was used as the working electrode, Ag / AgCl electrode as the reference electrode, and Pt sheet as the counter electrode. Electrochemical deposition was performed in the mixed solution at 10 mA / cm 2 The FeCo@NCW surface was electroplated with a constant current for 10 min, and the transition metal phosphide / hierarchical porous biomass carbon-based electrode material FeCoP / FeCo@NCW was finally obtained.

[0047] Example 2

[0048] A method for preparing a layered porous biomass carbon-based composite electrode material, wherein the difference from Example 1 is that: S11) the impregnation solution contains 2mmoLCo(NO3)2·6H2O, 1g dicyandiamide and 20mL ethanol, and the molar ratio of transition metal ions in the impregnation solution is Fe 3+ :Co 2+ =0:1. S21) Molar ratio of transition metal Fe in the electrodeposition solution 2+ :Co 2+ =0:1.

[0049] Example 3

[0050] A method for preparing a layered porous biomass carbon-based composite electrode material, wherein the difference from Example 1 is that: S11) the impregnation solution contains 0.5mmoLFe(NO3)3·9H2O, 1.5mmoLCo(NO3)2·6H2O, 1g dicyandiamide and 20mL ethanol, and the molar ratio of transition metal ions in the impregnation solution is Fe 3+ :Co 2+ =0.25:0.75. S21) Molar ratio of transition metal Fe in the electrodeposition solution 2+ :Co 2+ =0.25:0.75.

[0051] Example 4

[0052] A method for preparing a layered porous biomass carbon-based composite electrode material, wherein the difference from Example 1 is that: S11) the impregnation solution contains 1.5mmoLFe(NO3)3·9H2O, 0.5mmoLCo(NO3)2·6H2O, 1g dicyandiamide and 20mL ethanol, and the molar ratio of transition metal ions in the impregnation solution is Fe 3+ :Co 2+ =0.75:0.25. S21) Molar ratio of transition metal Fe in the electrodeposition solution 2+ :Co 2+ =0.75:0.25.

[0053] Example 5

[0054] A method for preparing a layered porous biomass carbon-based composite electrode material, wherein the difference from Example 1 is that: S11) the impregnation solution contains 2mmoLFe(NO3)3·9H2O, 1g dicyandiamide and 20mL ethanol, and the molar ratio of transition metal ions in the impregnation solution is Fe 3+ :Co 2+ =1:0. S21) Molar ratio of transition metal Fe in the electrodeposition solution 2+ :Co 2+ =1:0.

[0055] Example 6

[0056] A method for preparing a layered porous biomass carbon-based composite electrode material, which differs from Example 1 in that: S12) the high-temperature calcination temperature is 700°C.

[0057] Example 7

[0058] A method for preparing a layered porous biomass carbon-based composite electrode material, which differs from Example 1 in that: S12) the high-temperature calcination temperature is 900°C.

[0059] Example 8

[0060] A method for preparing a layered porous biomass carbon-based composite electrode material, which differs from Example 1 in that: S21) the total metal ion: phosphorus source (NaH2PO2·H2O) in the electrodeposition solution is 1:2, that is, the NaH2PO2·H2O content is 0.01 mol.

[0061] Example 9

[0062] A method for preparing a layered porous biomass carbon-based composite electrode material, which differs from Example 1 in that: S21) the total metal ion: phosphorus source (NaH2PO2·H2O) in the electrodeposition solution is 1:7, that is, the NaH2PO2·H2O content is 0.035 mol.

[0063] Comparative Example 10

[0064] A method for preparing a layered porous biomass carbon-based composite electrode material, which differs from Example 1 in that: there is no S2) step, and the electro-oxidation degradation performance of N-doped carbonized wood FeCo@NCW coated with a certain proportion of Fe and Co transition metals is tested.

[0065] Comparative Example 11

[0066] A method for preparing a layered porous biomass carbon-based composite electrode material, which differs from Example 1 in that: there is no S11) step, and the electro-oxidation degradation performance of the transition metal phosphide / biomass carbon-based electrode FeCoP / CW is tested.

[0067] Performance Testing

[0068] The electrocatalytic oxidation degradation rate of tetracycline by the layered porous biomass carbon-based composite electrodes proposed in Examples 1 to 9 and Comparative Examples 10 and 11 was tested in a three-electrode catalytic system: the layered porous biomass carbon-based composite electrodes provided in Examples 1 to 11 were added to the three-electrode catalytic system, with a platinum sheet as the cathode, the layered porous biomass carbon-based composite electrode as the anode, an Ag / AgCl electrode as the reference electrode, and Na2SO4 as the supporting electrolyte. The basic parameters were a pollutant concentration of 25 mg / L, an electrode spacing of 3 cm, and a current density of 10 mA / cm 2 The electrolyte Na2SO4 concentration was 0.1 mol / L. Tetracycline (TCH) degradation experiments were conducted on an electrochemical workstation, with 60 minutes of adsorption degradation and 60 minutes of electrooxidation degradation, for a total of 2 hours of degradation. A portion of the electrolyte was sampled at fixed intervals and the tetracycline content was determined by UV-visible absorption spectroscopy. The residual TCH content was divided by the original TCH concentration to obtain the degradation rate.

[0069] The performance test data is shown in Table 1 below:

[0070] Table 1. Comparison of the electrocatalytic oxidation degradation performance of pollutants TCH by the hierarchical porous biomass carbon-based composite electrodes provided in the examples

[0071]

[0072]

[0073] From the results of Examples 1 to 5, it can be seen that the proper doping of Fe elements in CoP can enhance the degradation performance of electrocatalytic oxidation pollutants, and the degradation rate can reach more than 85%. 3+ With Co 2+ When the molar ratio of the biomass carbon-based composite electrode provided by the present invention is 0.5:0.5, the degradation efficiency of TCH for electrocatalytic oxidation degradation reaches 93.10% within 60 minutes. 3+ When the amount of the substance is too large, that is, too much Fe element is doped, the degradation efficiency of the layered porous biomass carbon-based composite electrode provided by the present invention for electrocatalytic oxidation degradation of TCH will be greatly reduced. Figure 7 shown.

[0074] From the results of Example 1 and Example 7, it can be seen that the layered porous biomass carbon-based composite electrode obtained by high-temperature calcination in the temperature range of 800-900°C has a very high efficiency in degrading TCH, which can reach more than 92% within 60 minutes. At the same time, from the results of Example 6, it can be seen that when the calcination temperature of the layered porous biomass carbon-based composite electrode is 700°C, the efficiency of the layered porous biomass carbon-based composite electrode in catalytic degradation of TCH is greatly reduced. Figure 8 shown.

[0075] From the results of Examples 1, 8, and 9, it can be seen that the more phosphorus source is added to the electrodeposition solution, the higher the degradation efficiency of the layered porous biomass carbon-based composite electrode provided by the present invention for electrocatalytic oxidation degradation of TCH will be. When the phosphorus source is higher than 5 times, the degradation efficiency can reach more than 91%. However, considering the cost of the agent and the degradation effect, the ratio of metal ions to phosphorus source is 1:5, and the performance of the layered porous biomass carbon-based composite electrode provided by the present invention is the best. Figure 9 shown.

[0076] From Example 1 and Comparative Examples 10-11, it can be seen that when the layered porous biomass carbon-based composite electrode is not subjected to constant current deposition or metal ion impregnation before carbonization, the electrocatalytic oxidation performance of the electrode will be greatly affected, and the efficiency of degrading TCH will be greatly reduced. In particular, when the wood chips are not impregnated with metal ions before carbonization, the three-electrode catalytic system constructed using the layered porous biomass carbon-based composite electrode has a degradation efficiency of only 54.04% for the organic pollutant TCH within 60 minutes. This is because the layered porous biomass carbon-based composite electrode is not coated with a certain proportion of FeCo alloy and N doping, the overall conductivity of the electrode material is poor, and the electrochemical performance is low. In addition, the electrodeposited nanoparticles are prone to agglomeration, without exposing a large number of active sites, and without catalyzing the production of more hydroxyl radicals, the electrocatalytic degradation ability of the pollutant is reduced. However, when only impregnation and high-temperature calcination were performed, the degradation efficiency of the organic pollutant TCH by the three-electrode catalytic system constructed with layered porous self-supporting biomass carbon-based composite electrodes only reached 61.05% within 60 minutes. This is because the carbon layer-coated FeCo alloy has a poor ability to produce hydroxyl radicals, and the performance of electrocatalytic oxidation degradation of pollutants will be reduced.

[0077] Figure 2 This is a diagram showing the mechanism of the application of the layered porous biomass carbon-based composite electrode in the degradation of organic pollutants (R). Figure 2It can be seen that the oxidation effect of the layered porous biomass carbon-based composite electrode provided by the present invention on organic pollutants is indirect oxidation. During the indirect oxidation process, the transition metal nanoparticles M and phosphide MP coated and grown on the carbonized wood react with the hydroxyl radical ·OH to generate the product M(·OH). These active substances can oxidize R and thus degrade it.

[0078] Figure 5 The XRD patterns of the layered porous biomass carbon-based composite electrodes prepared in Examples 1 and 2 of the present invention are shown in FIG. Figure 3 and 4 It can be seen from the graph that the FeCoP alloy loaded on the surface of the electrode material provided by the present invention exhibits low crystallinity, indicating that a certain amount of Fe-doped CoP is loaded on the carbonized wood coated with the FeCo alloy.

[0079] Figure 6 The Raman spectra of the layered porous biomass carbon-based composite electrodes prepared in Examples 1, 3, and 4 of the present invention are shown in FIG. Figure 3 and 4 It can be seen that the carbon-based composite electrode material provided by the present invention has a -1 (D peak) and about 1580 cm -1 (G peak) all show typical carbon peaks, and the intensity ratio of the D peak to the G peak indicates the degree of graphitization. The smaller the ID / IG value, the higher the degree of graphitization. The higher the degree of graphitization, the higher the conductivity, and the electro-oxidation reaction provides a stronger charge transfer ability. The ID / IG value of the electrode material FeCoP / Fe1-xCox@NCW provided by the present invention decreases with the increase of Fe doping amount, among which the ID / IG value of FeCoP / Fe0.5Co0.5@NCW is the smallest, which is 0.891, indicating that its charge transfer ability is the best, and the ID / IG value of FeCoP / Fe0.75Co0.25@NCW is the largest, which is 0.966. The comparison of the experimental performance test can also show that its electrochemical properties are poor and its ability to degrade pollutants by electro-oxidation is low.

[0080] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a layered porous self-supporting biomass carbon-based composite electrode material, characterized by: The method comprises the following steps: S1: Discarded disposable wood products are cut into long wood chips 2-4 mm thick. Through impregnation and high-temperature calcination, N-doped self-supporting carbonized wood FeCo@NCW coated with a certain proportion of Fe and Co transition metals is constructed; S2: N-doped self-supporting carbonized wood FeCo@NCW coated with a certain proportion of Fe and Co transition metals is used for constant current electrodeposition to uniformly grow Fe-Co-P on the carbonized wood in situ to prepare a carbon-based composite electrode material.

2. The method for preparing a layered porous self-supporting biomass carbon-based composite electrode material according to claim 1, characterized in that: The step S1 comprises: S11: Cut a piece of disposable wood product into long wood chips 2-4 mm thick, immerse the wood chips in an ethanol solution containing Fe(NO3)3·9H2O, Co(NO3)2·6H2O, and dicyandiamide, and place them in an oven to immerse until the ethanol evaporates completely. Remove the wood chips and place them in an oven to dry. S12: The treated wood chips are placed in a tubular furnace and calcined at high temperature to obtain N-doped carbonized wood FeCo@NCW coated with a certain proportion of Fe and Co transition metals.

3. The method for preparing a layered porous self-supporting biomass carbon-based composite electrode material according to claim 2, characterized in that: In step S1, the impregnation solution contains 1 g of dicyandiamide and 20 mL of ethanol.

4. The method for preparing a layered porous self-supporting biomass carbon-based composite electrode material according to claim 2, wherein: The high temperature calcination process in step S1 is as follows: heating to 700-900° C. at a rate of 5° C. / min in a N 2 atmosphere and maintaining the pyrolysis for 2 hours.

5. The method for preparing a layered porous self-supporting biomass carbon-based composite electrode material according to claim 1, characterized in that: The step S2 comprises: S21: FeSO4·7H2O or Fe(NO3)3·9H2O, Co(NO3)2·6H2O, NaH2PO2·H2O and NH4Cl were dissolved in deionized water to prepare an electrodeposition solution; S22: In a standard three-electrode system, constant current electrochemical deposition was performed on the FeCo@NCW surface for a period of time using a constant current electrochemical deposition method to finally obtain the transition metal phosphide / hierarchical porous biomass carbon-based electrode material FeCoP / FeCo@NCW.

6. The method for preparing a layered porous self-supporting biomass carbon-based composite electrode material according to claim 5, characterized in that: The molar ratio of transition metal ions in the 50 mL electrodeposition solution in step S2 is the same as that in step S1, ethanol is 20 mL, and the molar ratio of metal ions to phosphorus source is 1:2-7.

7. The method for preparing a layered porous self-supporting biomass carbon-based composite electrode material according to claim 5, characterized in that: The electrodeposition process in step S2 is as follows: FeCo@NCW is used as the working electrode, Ag / AgCl electrode is used as the reference electrode, and Pt sheet is used as the counter electrode. The ... 2 The FeCo@NCW surface was electroplated with a constant current for 10 min, and the transition metal phosphide / hierarchical porous biomass carbon-based electrode material FeCoP / FeCo@NCW was finally obtained.

8. A layered porous self-supporting biomass carbon-based composite electrode prepared by the method for preparing a layered porous self-supporting biomass carbon-based composite electrode material according to any one of claims 1 to 7.

9. Use of the composite electrode according to claim 8 in a three-electrode catalytic system, characterized in that: In the three-electrode catalytic system, the platinum sheet is used as the cathode, the layered porous self-supporting biomass carbon-based composite electrode material is used as the anode, the Ag / AgCl electrode is used as the reference electrode, and Na2SO4 is used as the supporting electrolyte.

10. Use of the composite electrode according to claim 9 in a three-electrode catalytic system, characterized in that: A three-electrode catalytic system was used for electrocatalytic oxidation degradation of antibiotic organic pollutants. Relevant electrochemical tests and organic pollutant degradation experiments were conducted on an electrochemical workstation using a standard three-electrode system. The plate spacing in the three-electrode catalytic degradation system was 3 cm. The current density was 10 mA / cm 2 ; Pollutant concentration is 25mg / L; Electrolyte Na2SO4 concentration is 0.1moL / L.

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