CN111992233A - Core-shell nitrogen-doped iron metal nanoparticle, preparation method and electrocatalysis application thereof - Google Patents

Core-shell nitrogen-doped iron metal nanoparticle, preparation method and electrocatalysis application thereof Download PDF

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CN111992233A
CN111992233A CN202010724434.1A CN202010724434A CN111992233A CN 111992233 A CN111992233 A CN 111992233A CN 202010724434 A CN202010724434 A CN 202010724434A CN 111992233 A CN111992233 A CN 111992233A
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nitrogen
core
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nitrate
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张伟贤
王晶
范建伟
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Tongji University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/24—Nitrogen compounds
    • B01J35/33—
    • B01J35/618—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/082—Decomposition and pyrolysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/10—Heat treatment in the presence of water, e.g. steam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4676—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46133—Electrodes characterised by the material
    • C02F2001/46138—Electrodes comprising a substrate and a coating
    • C02F2001/46142—Catalytic coating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C02F2101/163—Nitrates

Abstract

The invention belongs to the field of environment functional materials, and provides a core-shell FeN-containing material with a carbon nitride shell layer wrapping an iron nitride coreNC nano-particles, a preparation method and application thereof. The core-shell nitrogen-doped iron metal nano-particles are core-shell nano-catalytic particles of iron nitride wrapped by a carbon nitride shell. The preparation method comprises the steps of taking Fe as an active element, sequentially adding graphite carbon nitride and a carbon source glucose, preparing Fe-C-N composite powder by a hydrothermal self-assembly method, and roasting to obtain the nano catalytic material. The content of the pyrrole nitrogen in the Fe nano-particles in the catalytic material can reach 17.4 at.%, and the specific surface area can reach 2040m2The NC shell layer wrapping structure improves the stability of the FeN active site; the working electrode prepared from the nano catalytic material has good denitrification performance in the environmental field, the nitrate removal rate can reach 5238-6004 mg N/g Fe, and the nitrogen selectivity is 78-91%.

Description

Core-shell nitrogen-doped iron metal nanoparticle, preparation method and electrocatalysis application thereof
Technical Field
The invention belongs to the field of environment functional materials, and particularly relates to core-shell nitrogen-doped iron metal nanoparticles, a preparation method and an electrocatalysis application thereof.
Background
Nitrogen exists in nature mainly in the form of organic nitrogen mainly including protein, amino acid, amide, urea, etc. and inorganic nitrogen mainly including NO3 -、NO2 -、NH4 +、N2NO and N2O, and the like. The nitrogen cycle maintains a nitrogen balance that is essential to all life in the earth in nature through inter-biological ammoniation, nitrification, denitrification, and nitrogen fixation. NO3 -Is the final product of the decomposition of nitrogenous organic matters through inorganic action, is the most stable nitrogenous compound in an aerobic environment, has high fluidity and high solubility, and is a key link for maintaining nitrogen balance in an ecological system. The excessive nutrient-rich oxygen salts such as nitrogen elements in the water body cause the excessive propagation of algae and other plankton, and the serious eutrophication of surface water bodies such as a sea river basin and the like is caused, so that the ecological system of the water body is disordered, the biological species are extinct, and a large-area dead water area is formed. For effectively reducing NO in water body3 -Content, finding an effective NO with low cost, convenient operation and wide application range3 -The removal technology becomes an important problem which needs to be solved at present.
Electrocatalytic NO with the rapid development of multifunctional nanomaterials and the efficient use of renewable energy sources3 -Reduction technology is receiving increasing attention from researchers because of its green and efficient nature. This technique greatly simplifies the operation and maintenance procedures and thereby increases NO3 -Cost-effective removal and environmental remediation, and more importantly, no addition of reactants to the reaction processAdding oxidant, reductant, coagulant and other chemical reagents can cause secondary pollution to environment. A great deal of research reports that bimetallic nano-materials of noble metals (such as Pd, Pt and Rh) and transition metals (such as Cu, Fe and Ni) have high catalytic NO efficiency3 -Reduction performance. However, the high cost of precious metals and their rapid deactivation (leaching) in water limit the large-scale application of bimetallic nanoelectrocatalysts in the field of environmental remediation.
Disclosure of Invention
The invention provides a method for preparing a denitrification catalyst, which aims at overcoming the defects of high cost, low nitrate removal rate, poor nitrogen selectivity and short service life of the existing denitrification catalyst. The invention aims to solve the technical problem of providing a core-shell FeN-NC nano particle with an NC shell wrapping FeN sites, combining the advantages of an electrochemical reduction method, controlling the multi-electron transfer of nitrate reduction by adjusting the thickness of the NC shell, and selectively reducing nitrate in a water body into nitrogen.
Aiming at the technical problems, the invention uses non-toxic and cheap transition metal Fe to prepare the electrocatalyst so as to replace the precious metal-based bimetallic nano-catalyst. The nZVI is used as an economic and environment-friendly electron donor, has high specific surface area and strong reduction activity, and can quickly reduce NO in water3 -. However, the too strong reducing power of nZVI results in the formation of more ammonium (NH) as by-product4 +) Moreover, the nZVI is easy to inactivate in water environment, and hydrogen is easy to generate in the reaction process. Therefore, nitrogen doping is required to be introduced to regulate and control the supply capacity of nZVI, so that FeN nanoparticles slowly release electrons to convert NO3 -Highly selective reduction to N2While increasing the cycle life of nZVI.
The invention synthesizes the nitrogen-doped Fe nano-particles (FeN-NC) encapsulated by carbon nitride for electrocatalytic reduction of NO3 -The multi-electron transfer path and speed from the nano-iron to the nitrate can be regulated and controlled by adjusting the thickness of the NC shell layer, and meanwhile, the porous structure of the NC shell provides adsorption, activation and electroreduction sites for the nitrate, so that the nitrate is converted into nitrogen efficiently. The iron-nitrogen catalyst eliminates noble metal and toxic heavy metalsUse of metals (e.g. Pd, Pt, Cu, Ni) and minimization of NO3 -Undesirable by-products (e.g., NH) from reaction with nano zero-valent iron (nZVI)3) And has high cost efficiency and environmental benefit. The invention not only provides an idea for developing and designing a green Fe-based nano material with better performance, but also solves the problem that the total nitrogen emission of a sewage plant is difficult to reach the standard, and has the functions of removing COD (chemical oxygen demand) and decoloring and deodorizing. Provides a new thought and scientific basis for the large-scale application and the actual landing of the electrochemical nano denitrification in the aspects of water purification, wastewater treatment and environmental remediation.
The present invention has been completed based on the above-described concept.
In one aspect, the invention provides core-shell nitrogen-doped iron metal nanoparticles, which are core-shell catalytic nanoparticles of iron nitride (FeN-NC) wrapped by a carbon nitride shell.
The preparation method of the core-shell nitrogen-doped iron metal nano-particles comprises the following steps: and mixing and pyrolyzing the self-assembled Fe-C-N compound, and obtaining the core-shell nano catalytic material of iron nitride wrapped by the carbon nitride shell through migration and rearrangement of elements.
The method comprises the following specific steps:
(1) putting a nitrogen source and a carbon source into water, uniformly mixing to form a uniform dispersion system, and adding an iron salt solution into the uniform dispersion system to perform hydrothermal reaction to prepare a Fe-C-N compound; wherein: nitrogen source: the molar ratio of the carbon source to the ferric salt is (0.7-1.2) to (2.6-3.3) to (0.8-1.4), the temperature of the hydrothermal reaction is controlled to be 100-180 ℃, and the time of the hydrothermal reaction is 8-15 h;
(2) and (2) drying the product obtained in the step (1), roasting in a tubular furnace, pyrolyzing at 400-1000 ℃ for 1-6h under the condition that the pyrolysis atmosphere is nitrogen and the gas flow rate is 90-150 mL/min, and reacting to obtain the core-shell FeN-NC.
Nitrogen source in step (1): the molar ratio of the carbon source to the iron salt can be adjusted within the range of (0.7-1.2): (2.6-3.3): 0.8-1.4, for example, 1: 4: 2,1: 4: 1,1: 3: 1,1: 3: 2,2: 6: 3, and so on.
The temperature and time of the hydrothermal reaction in step (1) may be adjusted together, for example, the temperature and time of the hydrothermal reaction are 100 ℃ and 8 hours, 120 ℃ and 10 hours, 120 ℃ and 15 hours, 130 ℃ and 10 hours, 140 ℃ and 8 hours, 140 ℃ and 12 hours, 150 ℃ and 10 hours, 160 ℃ and 15 hours, respectively, and the like.
Preferably, the drying in step (2) can be carried out in an oven at a temperature ranging from 80 to 140 ℃. E.g., 80, 90, 95, 100, 102, 105, 110, 115, 120, 125, 130, 135, 140 ℃, etc.
The gas flow rate of the pyrolysis gas in the step (2) can be adjusted according to actual conditions, for example, 90, 92, 100, 103, 105, 108, 110, 112, 113, 115, 118, 120, 130, 135, 140, 145mL/min, and the like are adopted.
In step (2), the pyrolysis reaction temperature and time can be 400-1000 ℃ and 1-6h respectively, and the time required for higher temperature is generally shorter, such as 400 ℃ for 4h, 800 ℃ for 2-3h, 1000 ℃ for 1, 2, 3, 3.5 or 4h, etc.
Preferably, the iron salt is ferric chloride or ferric nitrate.
Preferably, the carbon source is glucose or carboxymethyl cellulose.
Preferably, the nitrogen source is g-C3N4。
Preferably, the mass percentage of the iron salt solution is 5-40%.
For example, the weight percentage of the iron salt solution is 5-30%, 20-35%, 25-35%, etc., such as 5, 10, 15, 20, 25, 30, 35%, etc.
On the other hand, the invention also provides application of the core-shell nitrogen-doped iron metal nano-particles, namely the core-shell nitrogen-doped iron metal nano-particles are used for preparing working electrodes and are applied to denitrification treatment of water bodies.
For example, a FeN-NC nano catalytic material, carbon black and polyvinylidene fluoride are coated on a nickel screen to form a working electrode according to the mass volume ratio of (2-5 mg) to (0.3-1 mg) to (40-80 mu L), and a platinum electrode is used as a counter electrode and a calomel electrode is used as a reference electrode to form a three-electrode system; the three-electrode system is placed in a water body containing nitrate for denitrification treatment.
The size of the forceps mesh is preferably determined by the working electrode, and for example, nickel mesh (1 to 1.5cm) × (1.2 to 1.5cm) can be used.
Preferably, the concentration of the nitrate in the nitrate-containing water body is 20-300mgN/L, Na2SO4Na in mixed electrolyte with NaCl2SO4The concentration of the sodium chloride is 0.06-0.2mol/L, the concentration of NaCl is 0.01-0.05mol/L, the applied voltage is-1.1 to-1.5, and the denitrification time is 1-28 h.
According to the invention, the mass-volume ratio of the FeN-NC nano catalytic material to the polyvinylidene fluoride is (2-5 mg) to (0.3-1 mg) to (40-80 mu L). For example, the ratio of the three is 2mg:0.3mg: 40. mu.L, 2mg:0.3mg: 80 μ L, 3mg:0.4mg:50 μ L, 3mg:0.6mg:50 μ L, 4mg:0.3mg:40 μ L, 4mg:0.7mg:70 μ L, 4mg:0.8mg:70 μ L, 5mg:0.7mg:80 μ L, 5mg:0.4mg:40 μ L, and so forth.
The FeN-NC nano catalytic material is the core-shell nitrogen-doped iron metal nano particle.
Preferably, the concentration of the nitrate in the nitrate-containing water body is 20-300 mgN/L. For example, 20, 40, 50, 60, 80, 85, 90, 100, 120, 130, 150, 180, 200, 205, 210, 220, 230, 250, 270, 280, 290mgN/L, etc. are used.
The water body containing the nitrate also contains Na2SO4And NaCl. Na in the mixed electrolyte2SO4The concentration of (A) is 0.06-0.2 mol/L. For example, 0.07, 0.10, 0.11, 0.12, 0.14, 0.15, 0.18, 0.20mol/L, etc. The concentration of NaCl is 0.01-0.05mol/L, e.g., 0.01, 0.02, 0.04, 0.05mol/L, etc.
Preferably, the applied voltage is from-1.1 to-1.5V, e.g., -1.1, -1.3, -1.4, -1.5 volts, and so forth.
Preferably, the denitrification time is 1-28 h. E.g., 1, 4, 6, 8, 10, 12, 13, 15, 17, 19, 20, 22, 25, 26, 27, 28 hours, etc.
The invention has the following beneficial effects:
the invention provides a preparation method of core-shell iron nitride metal nanoparticles, which can be effectively adjustedThe electron-donating capability of the FeN active site is saved, and the reaction activity and stability of the catalyst are improved. By adjusting the thickness of the NC shell, NO can be regulated3 -Reduction to N2The electron transfer process of (1) to promote the target product N2Selectivity of (a); the FeN-NC-140 with a thin shell structure has higher specific surface area (2040 m)2/g) and pyrrole nitrogen content (17.4% at%) to achieve very high N2Selectivity (91%) and NO3 -Removal capacity (6004mg N/g Fe); after 15 continuous electrocatalytic cycles, the FeN-NC-140 still maintains higher electrocatalytic reduction activity and N2The selectivity shows that the NC shell wrapping structure can effectively protect FeN active sites and enhance the recycling performance and stability of the FeN nano material; the nuclear shell FeN-NC nano catalyst overcomes the defect that nano zero-valent iron (nZVI) can rapidly react NO in water3 -Reduction to ammonium (NH)4 +) Has a limitation of NO3 -High removal efficiency and target product N2Controllable selectivity, low raw material cost, and electrocatalysis of NO3 -The reduction process has the advantage of no secondary pollution to water, and is expected to be a large-scale industrialized nano catalyst.
Drawings
FIG. 1 is a TEM photograph of NC in example 1 of the present invention.
FIG. 2 is a TEM image of FeN-NC-120 in example 1 of the present invention.
FIG. 3 is a TEM image of FeN-NC-140 in example 1 of the present invention.
FIG. 4 is a TEM image of FeN-NC-160 in example 1 of the present invention.
Fig. 5 shows the nitrogen selectivity of the series of fe-based materials in example 1 of the present invention.
FIG. 6 shows the nitrate removal rate and the cycle stability of FeN-NC-140 and its blank control group in example 1 of the present invention.
FIG. 7 shows the removal capacity and nitrogen selectivity of FeN-NC-140 for different concentrations of nitrate in example 1 of the present invention.
FIG. 8 is a graph showing the cycling stability of FeN-NC-140 for nitrate removal in example 1 of the present invention.
Detailed Description
The present invention is further illustrated by the following examples, which are intended to be illustrative of the invention and are not to be construed as limiting the invention.
Example 1
1. The preparation method of the core-shell nitrogen-doped iron metal nanoparticles comprises the following specific steps:
(1) g to C3N4Adding (1.2mol) and glucose (3.2mol) into water, mixing uniformly to form a uniform dispersion system, adding a ferric chloride (1.0mol) solution into the uniform dispersion system, carrying out ultrasonic reaction for 3h, then transferring into a hydrothermal reaction kettle, reacting for 12h at 140 ℃, washing and centrifuging the prepared Fe-C-N compound, and then placing at 10 ℃ for vacuum drying for 6 h.
(2) And (2) pyrolyzing the product obtained in the step (1) in a tubular furnace in nitrogen (80mL/min) atmosphere at the high temperature of 800 ℃ for 2h to obtain the core-shell FeN-NC-140 nano catalytic material.
2. The obtained nuclear shell nitrogen-doped iron metal nano material is applied to electrocatalytic denitrification
Coating the FeN-NC nano catalytic material (4mg) of carbon black and polyvinylidene fluoride (PVDF) on a nickel screen (1cm multiplied by 1.2cm) according to the weight ratio of 8:1:1, respectively drying for 6h and 10h at 60 ℃ and 120 ℃ in vacuum to prepare a working electrode, and forming a three-electrode system by taking a platinum electrode as a counter electrode and a calomel electrode as a reference electrode. The system is placed in mixed electrolyte Na with initial concentration of nitrate of 100mgN/L2SO4And 20mL of a reaction solution containing NaCl at concentrations of 0.1mol/L and 0.02mol/L, respectively. After 24h of electrocatalytic reaction, the nitrogen selectivity is 91%, and the nitrate removal capacity is 6004mg N/g Fe catalyst.
As can be seen from fig. 1, NC is a thin layer structure having many wrinkles and pores, providing a high specific surface area and a wide pore distribution.
As can be seen from the sequence of FIGS. 2, 3 and 4, the FeN-NC-120 wraps a thick NC shell, the FeN-NC-140 wraps a thin NC shell, and the FeN-NC-160 has no shell structure.
As can be seen from fig. 5, the prepared FeN-NC-140 nanoparticles exhibited the highest nitrogen selectivity compared to the control series of Fe-based materials, NC and nZVI.
As can be seen from FIG. 6, the nitrate removal efficiency of FeN-NC-140 is not significantly reduced, the nitrate removal rate of FeN-140 is significantly reduced, and nZVI is easily inactivated as the number of reaction cycles is increased.
As can be seen from FIG. 7, as the nitrate concentration was increased from 20 to 200mgN/g, the nitrate nitrogen removal capacity increased from 1292 mgN/g Fe to 9514 mgN/g Fe, and the nitrogen selectivity decreased from 91% to 81%. The catalyst also has good denitrification effect on large-volume nitrate, and the electric energy utilization efficiency of denitrification reaction is increased along with the increase of the concentration of the nitrate.
As can be seen from fig. 8, the rate constant of nitrate nitrogen remained unchanged and the nitrate removal capacity slightly decreased after 15 consecutive electrocatalytic denitrification cycles, indicating that the catalyst can maintain better reaction kinetics and cycle stability.
Example 2
Preparation of core-shell iron nitride metal nanoparticles and a method for catalytic reduction of nitrate were as in example 1, except that the hydrothermal temperature for the preparation of FeN-NC was 120 ℃, the nitrogen selectivity of the obtained catalyst FeN-NC-120 was 81%, and the nitrate removal capacity was 5406mg N/g Fe.
Example 3
Preparation of core-shell iron nitride metal nanoparticles and a method for catalytic reduction of nitrate were as in example 1, except that no iron salt was added during the preparation of the catalyst, the nitrogen selectivity of the prepared NC-140 catalyst was 20%, and the removal capacity of nitrate was 81mg N/g catalyst.
Example 4
The preparation of core-shell iron nitride metal nanoparticles and the method for catalytic reduction of nitrate were as in example 1, except that no carbon source was added during the preparation of the catalyst, the nitrogen selectivity of the FeC-140 catalyst prepared was 36%, and the nitrate removal capacity was 2490mgN/g Fe.
Example 5
The preparation of the core-shell iron nitride metal nanoparticles and the method for catalytic reduction of nitrate are as in example 1, except that the nitrate concentration of the system is 50mL, the coating amount of the nano catalytic material is 3mg, after the electrocatalytic reaction for 12 hours, the nitrogen selectivity is 92%, and the removal capacity of the nitrate is 3144mgN/g Fe.
Example 6
The preparation of the core-shell iron nitride metal nanoparticles and the method for catalytic reduction of nitrate are as in example 1, except that the system selects eutrophic lake water samples for electro-catalytic denitrification experiments, and the eutrophic lake water samples are directly used after filtration of floating algae. After 4h of reaction, the nitrate concentration was reduced from 20.1 to 3.6mgN/L, the nitrogen selectivity was 90%, and the nitrate removal capacity was 1346mgN/g Fe.
The embodiments described above are presented to enable a person having ordinary skill in the art to make and use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the embodiments described herein, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims (10)

1. The core-shell nitrogen-doped iron metal nanoparticle is characterized in that the core-shell nitrogen-doped iron metal nanoparticle is a core-shell nano catalytic particle formed by wrapping iron nitride with a carbon nitride shell.
2. The preparation method of the core-shell nitrogen-doped iron metal nanoparticle, according to claim 1, is characterized in that the Fe-C-N composite is mixed and pyrolyzed to obtain the core-shell nano catalytic material of iron nitride coated by a carbon nitride shell, and the specific steps are as follows:
(1) putting a nitrogen source and a carbon source into water to form a uniform dispersion system, and adding an iron salt solution into the uniform dispersion system to perform hydrothermal reaction to prepare a Fe-C-N compound; wherein: nitrogen source: the molar ratio of the carbon source to the ferric salt is (0.7-1.2) to (2.6-3.3) to (0.8-1.4), the temperature of the hydrothermal reaction is controlled to be 100-180 ℃, and the time of the hydrothermal reaction is 8-15 h;
(2) and (2) drying the product obtained in the step (1), roasting in a tubular furnace, pyrolyzing at 400-1000 ℃ for 1-6h under the condition that the pyrolysis atmosphere is nitrogen and the gas flow rate is 90-150 mL/min, and reacting to obtain the core-shell FeN-NC.
3. The method of claim 2, wherein the iron salt is ferric chloride or ferric nitrate.
4. The method according to claim 2, wherein the carbon source is glucose or carboxymethyl cellulose.
5. The method according to claim 2, wherein the nitrogen source is g-C3N4。
6. The method according to claim 2, wherein the drying temperature in step (2) is in the range of 80 to 140 ℃.
7. The method according to any one of claims 1 to 6, wherein iron in the iron salt solution is 5 to 40% by mass of the solution.
8. The use of the core-shell nitrogen-doped iron metal nanoparticle of claim 1, wherein the core-shell nitrogen-doped iron metal nanoparticle is used to prepare a working electrode for denitrification treatment of water.
9. The application of the catalyst is characterized in that the FeN-NC nano catalytic material, the carbon black and the polyvinylidene fluoride are coated on a nickel mesh to prepare a working electrode according to the mass-volume ratio of (2-5 mg) to (0.3-1 mg) to (40-80 μ L), and a platinum electrode is used as a counter electrode and a calomel electrode is used as a reference electrode to form a three-electrode system; the three-electrode system is placed in a water body containing nitrate for denitrification treatment.
10. Use according to claim 9, characterized in that: the concentration of the nitrate in the nitrate-containing water body is 20-300 mgN/L;
the water body containing the nitrate also contains Na2SO4And NaCl; na (Na)2SO4The concentration of the NaCl is 0.06-0.2mol/L, and the concentration of the NaCl is 0.01-0.05 mol/L;
the applied voltage is-1.1 to-1.5V, and the denitrification time is 1 to 28 hours.
CN202010724434.1A 2020-07-24 2020-07-24 Core-shell nitrogen-doped iron metal nanoparticle, preparation method and electrocatalysis application thereof Pending CN111992233A (en)

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CN112473716A (en) * 2020-11-30 2021-03-12 同济大学 Nitrogen-doped mesoporous carbon-based nano material loaded with copper-nickel alloy particles and preparation method and application thereof
CN113233551A (en) * 2021-05-20 2021-08-10 燕山大学 Preparation method of catalytic reduction nitrate electrode and resource utilization technology thereof
CN113877580A (en) * 2021-09-10 2022-01-04 南开大学 Fe0Base-ordered mesoporous carbon electrocatalyst and preparation method and application thereof
CN116212968A (en) * 2023-03-06 2023-06-06 安徽大学 "nested child" catalyst with carbon-rich surface defect and preparation method and application thereof

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