Preparation and application of a nickel-iron bimetallic multi-component composite porous fiber material

Abstract

The application discloses a preparation method of a nickel-iron bimetallic multi-component composite porous fiber material, which comprises the following steps: dissolving phenylenediamine Schiff base, polyacrylonitrile, iron salt and nickel salt in N,N-dimethylformamide to form a transparent solution, and then electrospinning the solution under a voltage of 16kV to obtain a precursor fiber; and the prepared precursor fiber is first treated in a tubular furnace under N2 atmosphere, heated to 700-900 DEG C and treated for 2-6h to obtain a carbonized fiber; and the carbonized fiber is treated in the tubular furnace with sodium hypophosphite as a phosphorus source, heated to 350 DEG C and treated for 4-8h to obtain the nickel-iron bimetallic multi-component composite porous fiber material. The phenylenediamine Schiff base is used as a ligand and main carbon source and nitrogen source, the polyacrylonitrile is used as an auxiliary carbon source and nitrogen source, and the sodium hypophosphite is used as a phosphorus source, so that the operation is simple and the cost is low. The composite material has excellent catalytic activity and good stability for electrocatalytic hydrogen evolution, oxygen evolution and hydrogen production by water electrolysis under alkaline conditions, and has a good application prospect in the hydrogen production by water electrolysis technology.

Description

Technical Field

[0001] This invention relates to the preparation and application of a nickel-iron bimetallic multi-component composite porous fiber material, and more particularly to a method of using a phenylenediamine Schiff base as a ligand to coordinate metal ions in order to prepare a nickel-iron bimetallic multi-component composite porous fiber material with uniform composition and distribution. It is mainly used for electrocatalytic hydrogen evolution (HER), oxygen evolution (OER), and water electrolysis reactions in alkaline media. Background Technology

[0002] For the past two centuries, fossil fuels have fueled exponential economic growth. However, excessive use of fossil fuels has led to problems such as the greenhouse effect, environmental degradation, and energy shortages. Hydrogen energy, as one of the cleanest energy sources, shows great potential in addressing these issues. Water electrolysis is considered one of the most promising hydrogen production technologies for large-scale application. However, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) require highly efficient catalysts to improve the kinetic reaction rates and reduce the overpotential of the reactions. To date, Pt / C and RuO2 / IrO2 have been considered the best catalysts for HER and OER, respectively. However, the high cost of these rare and expensive catalysts severely limits their large-scale application. Therefore, developing abundant and inexpensive non-precious metal catalysts has become a significant research area.

[0003] Transition metal compounds, especially transition metal phosphides, nitrides, and alloys, have proven to be high-performance non-noble metal HER and OER catalysts. Heteroatom-doped carbon-based materials, due to their high conductivity and corrosion resistance, are also used as HER and OER catalysts and supports. The structure and composition of single-metal and single-component catalysts have certain limitations and cannot meet the needs of high-performance catalysis. Therefore, the preparation of multi-metal catalysts through doping with other metal ions and the preparation of multi-component composite catalysts by combining different catalysts have become the main methods for constructing multi-metal, multi-component, and multifunctional high-efficiency composite catalysts. The introduction of heteroatoms can effectively regulate the electronic structure (or optimize orbital electron occupancy) and modulate the interaction between active sites and reactants, thereby preparing more efficient transition metal composite electrocatalysts. The combination of different catalysts can achieve complementary advantages between different components, producing a synergistic effect. Furthermore, morphology and size are also important factors affecting the catalytic performance of catalysts. It has been proven that one-dimensional fibrous structures are beneficial for improving mass transfer and charge transport rates, thereby enhancing catalytic reaction kinetics. Based on the above considerations, this invention utilizes a simple electrospinning technique combined with pyrolytic carbonization and phosphating to prepare a four-component composite catalyst consisting of nickel-iron bimetallic nitride (FeNi3N), phosphide (FeNi2P), alloy (FeNi3), and N-doped carbon fiber. The prepared catalyst exhibits superior catalytic performance in electrocatalyzing HER, OER, and water electrolysis under alkaline conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a simple, effective, and controllable method for preparing nickel-iron bimetallic multi-component composite materials with porous fiber structures.

[0005] Another object of the present invention is to provide the application of the composite material in electrocatalytic HER, OER and water electrolysis.

[0006] I. Preparation of Nickel-Iron Bimetallic Multi-component Composite Porous Fiber Materials

[0007] The preparation of the nickel-iron bimetallic multi-component composite porous fiber material of the present invention includes the following process steps:

[0008] (1) Preparation of precursor: Phenylenediamine Schiff base, polyacrylonitrile (PAN), iron salt, and nickel salt were dissolved in N,N-dimethylformamide to form a transparent solution. The solution was transferred to a syringe, and precursor fibers were obtained by electrospinning at 16 kV. The numerous C=N double bonds in the Schiff base can coordinate with nickel and iron ions, resulting in uniform dispersion of nickel and iron ions in the fiber. At the same time, the C=N double bonds can significantly increase the nitrogen content of the target catalyst, providing more active sites for the final electrocatalyst.

[0009] Polyacrylonitrile (PAN) serves as both a carbon and nitrogen source and is a key raw material for adjusting the viscosity of the spinning solution. The mass ratio of PAN to phenylenediamine Schiff base is 1:1-1:3; the molar ratio of iron salt to nickel salt is 1:2-1:4; and the mass ratio of PAN, phenylenediamine Schiff base, and solvent N,N-dimethylformamide is 1:8-1:12.

[0010] (2) Preparation of nickel-iron bimetallic multi-component composite porous fiber material: The precursor prepared above is first heated to 700-900°C (preferably 800°C) at a rate of 3-5 °C / min (preferably 4 °C / min) in a tube furnace under N2 atmosphere for 2-6 h (preferably 4 h) to obtain carbonized fibers containing metallic nickel and iron through carbothermic reduction reaction; the carbonized fibers are then heated to 350°C in a tube furnace with sodium hypophosphite as phosphorus source at a rate of 1-3 °C / min (preferably 2 °C / min) for 4-8 h (preferably 5 h) to obtain nickel-iron bimetallic multi-component composite porous fiber material.

[0011] The mass ratio of sodium hypophosphite to carbonized fiber is 1:10-1:20. The prepared composite material consists of four components: nickel-iron bimetallic nitride (FeNi3N), phosphide (FeNi2P), alloy (FeNi3), and N-doped carbon fiber (NCF). The mass fractions of FeNi3N, FeNi2P, FeNi3, and NCF are 9-15%, 12-22%, 15-25%, and 38-64%, respectively. The composite porous fiber material has a diameter of 200 nm and a specific surface area of ​​185-326 m². 2 / g, pore volume 0.35-0.52 cm³ 3 .

[0012] II. Structure of Carbon Composite Porous Fiber Materials

[0013] Figure 1 This is a SEM image of the catalyst prepared in Example 1 of the present invention. As can be seen from the image, the prepared catalyst is a porous fiber with a diameter of approximately 200 nm.

[0014] Figure 2 This is the XRD pattern of the catalyst prepared in Example 1 of this invention. As shown in the figure, all four catalysts prepared are composed of four components: FeNi3N, FeNi2P, FeNi3, and NCF. The diffraction peaks at 2θ of approximately 23.6° and 37.2° are attributed to the (100) and (111) crystal planes of FeNi2P (PDF#50-1434); the diffraction peaks at 2θ of approximately 41.5° and 50.1° are attributed to the (231) and (222) crystal planes of FeNi3N (PDF#51-1367); the diffraction peaks at 2θ of approximately 75.6° and 91.9° are attributed to the (220) and (311) crystal planes of FeNi3 (PDF#65-3244); and the diffraction peak at 2θ of approximately 22.5° is attributed to the (002) crystal plane of NCF.

[0015] Figure 3 This is the N2 adsorption-desorption isotherm of the catalyst prepared in Example 1 of this invention. As shown in the figure, the prepared sample exhibits a type II isotherm and a hysteresis loop, indicating that the sample has a hierarchical porous structure. The specific surface area of ​​the sample is 308 m². 2 / g, pore volume 0.48 cm³ 3 / g.

[0016] Figure 4 This is a pore size distribution diagram of the catalyst prepared in Example 1 of the present invention. As can be seen from the figure, the obtained sample has a wide pore size distribution range, between 2 and 120 nm, and is mainly concentrated in the mesoporous range of 20-40 nm, which further proves that the catalyst has abundant mesoporous and macroporous structures.

[0017] III. Performance of Nickel-Iron Bimetallic Multi-Component Composite Porous Fiber Materials

[0018] Electrodes for electrocatalytic hydrogen evolution, oxygen evolution, and water electrolysis were fabricated using the composite material: A certain amount of the composite material was ultrasonically dispersed in ethanol, and an appropriate amount of 5% Nafion solution was added and mixed thoroughly to prepare a suspension. A certain amount of this suspension was drop-coated onto a glassy carbon electrode and allowed to air dry to prepare the working electrode for electrocatalytic hydrogen evolution and oxygen evolution; a certain amount of this suspension was also drop-coated onto treated nickel foam to prepare the working electrode for electrocatalytic water splitting. Electrochemical performance tests were conducted using a CHI760E electrochemical workstation.

[0019] Figure 5 This is the LSV curve of the catalyst prepared in Example 1 of this invention catalyzing HER in 1 M KOH. As shown in the figure, the obtained catalyst achieves a current density of 10 mA / cm² when catalyzing HER in 1.0 M KOH. 2 The overpotential was 128 mV, which proves that the catalyst has excellent catalytic activity for HER.

[0020] Figure 6 This is the LSV curve of the catalyst prepared in Example 1 of this invention catalyzing OER in 1 M KOH. As shown in the figure, the obtained catalyst achieves a current density of 10 mA / cm² when catalyzing OER in 1.0 M KOH. 2 The overpotential was 222 mV, which proves that the catalyst has excellent catalytic activity for OER.

[0021] Figure 7 This is the LSV curve of the catalyst prepared in Example 1 of this invention for catalytic water electrolysis in 1 M KOH. As shown in the figure, the obtained catalyst achieves a current density of 10 mA / cm² when catalyzing the total decomposition of water in 1.0 M KOH. 2 The decomposition voltage was 1.56 V, proving that the catalyst, as a bifunctional catalyst for HER and OER, has excellent catalytic activity for water electrolysis.

[0022] Figure 8 This is the relative current density-time curve of the catalyst prepared in Example 1 of this invention for catalytic water electrolysis in 1 M KOH. As shown in the figure, after 10 hours of stability testing, the current density of the obtained catalyst decreased by only 19.1%, proving that the catalyst has strong stability in the process of catalytic water electrolysis.

[0023] The above test results indicate that in a 1.0 M KOH solution, at 10 mA / cm², 2At the specified current density, the overpotential of this catalyst for HER can be as low as 128 mV, the overpotential for OER can be as low as 222 mV, and the decomposition voltage for water electrolysis can be as low as 1.56 V, and it also exhibits good cycling stability.

[0024] The reaction mechanism of this invention is as follows: using phenylenediamine Schiff base as the main carbon and nitrogen source, polyacrylonitrile as the auxiliary carbon and nitrogen source, and iron and nickel salts as metal sources, phenylenediamine Schiff base, polyacrylonitrile, iron and nickel salts are dissolved in DMF. The numerous C=N double bonds in the phenylenediamine Schiff base have strong coordination ability and can be uniformly dispersed by coordinating with metal ions. The resulting solution is then electrospun, allowing polyacrylonitrile to form fibers under high electrostatic voltage. Simultaneously, metal ions chelate and stabilize on the fiber surface, thereby generating a precursor with uniformly distributed metal species on the surface. During the heat treatment of the obtained precursor in a tube furnace under a N2 atmosphere, the precursor undergoes a carbothermic reduction reaction to form N-doped carbon fibers (NCF) with good electrical conductivity, as well as metal nitrides (FeNi3N) and metal alloys (FeNi3), while removing metal oxide impurities. In the phosphating process of carbonized fibers using sodium hypophosphite as the phosphorus source, metal phosphides (FeNi2P) are generated, resulting in a four-component composite porous fiber material composed of FeNi3N, FeNi3, FeNi2P, and NCF. The composition, structure, and catalytic performance of the catalyst can be controlled by adjusting the mass ratio of phenylenediamine Schiff base to PAN, the molar ratio of iron salt to nickel salt, the mass ratio of PAN + phenylenediamine Schiff base to DMF solvent, as well as the spinning voltage, the temperature and reaction time of the carbonization and phosphating heat treatments. For example, increasing the proportion of phenylenediamine Schiff base increases the FeNi3N content in the catalyst, and increasing the spinning voltage increases the diameter of the generated carbon fibers. Increasing the proportion of sodium hypophosphite during phosphating increases the FeNi2P content. Increasing the PAN content generates more gas during heat treatment, resulting in a richer pore structure in the final catalyst, which is beneficial for improving mass transfer and charge transport kinetics, thereby enhancing its catalytic activity.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. By effectively combining four active components—FeNi3N, FeNi2P, FeNi3, and NCF—a heterogeneous interface is formed between the different components, resulting in a synergistic effect. This endows the catalyst with excellent intrinsic catalytic activity for both HER and OER bifunctionality and superior interfacial charge transport rate, thereby improving the electrochemical reaction rate of HER and OER catalysis.

[0027] 2. Using phenylenediamine Schiff base as ligand, the C=N double bond is more conducive to the formation of nitrides and increases the nitrogen content of the final catalyst compared to the CN single bond.

[0028] 3. Using transition metals nickel and iron as metal sources, the strong coordination between the numerous coordinating groups contained in phenylenediamine Schiff base and PAN and metal ions is utilized to chelate the metal ions, resulting in a final catalyst with uniform distribution of active sites, uniform catalytic activity, and good stability.

[0029] 4. The porous carbon fiber structure not only accelerates the penetration of electrolytes, but also provides more channels for rapid mass transfer during the reaction process, which is beneficial to improving catalytic performance.

[0030] 5. Activity tests show that the composite material prepared in this invention has excellent electrocatalytic activity and good stability for hydrogen evolution, oxygen evolution and water electrolysis reactions in alkaline media, and has broad application prospects. Attached Figure Description

[0031] Figure 1 This is a SEM image of the catalyst prepared in Example 1 of this invention.

[0032] Figure 2 This is the XRD pattern of the catalyst prepared in Example 1 of this invention.

[0033] Figure 3 This is the N2 adsorption-desorption isotherm of the catalyst prepared in Example 1 of this invention.

[0034] Figure 4 This is a pore size distribution diagram of the catalyst prepared in Example 1 of the present invention.

[0035] Figure 5 This is the LSV curve of HER catalyzed by the catalyst prepared in Example 1 of this invention in 1 M KOH.

[0036] Figure 6 This is the LSV curve of the catalyst prepared in Example 1 of this invention catalyzing OER in 1 M KOH.

[0037] Figure 7 This is the LSV curve of the catalyst prepared in Example 1 of this invention for catalytic electrolysis of water in 1 M KOH.

[0038] Figure 8 This is the relative current density-time curve of the catalyst prepared in Example 1 of this invention for catalytic electrolysis of water in 1 M KOH. Detailed Implementation

[0039] The present invention will now be described in more detail through specific embodiments.

[0040] Example 1

[0041] (1) Preparation of precursor: 4.0 g PAN, 8.0 g phenylenediamine Schiff base, 0.606 g (1.5 mmol) Fe(NO3)3·9H2O and 1.308 g (4.5 mmol) Ni(NO3)3·6H2O were dissolved in 100 mL DMF to form a transparent solution. The mass ratio of PAN to phenylenediamine Schiff base was 1:2, the molar ratio of iron salt to nickel salt was 1:3, and the mass ratio of PAN + phenylenediamine Schiff base to solvent DMF was 1:8. The solution was transferred to a syringe, and the precursor was prepared by electrospinning at a flow rate of 1.5 mL / h and a voltage of 16.5 kV. The distance between the collecting plate and the needle was 18 cm.

[0042] (2) Preparation of nickel-iron bimetallic multi-component composite porous fiber material: The precursor prepared in (1) was first heat-treated in a tube furnace at 800°C for 4 hours under N2 atmosphere, with a heating rate of 4°C / min, to generate carbonized fibers through carbothermic reaction. Then, the carbonized fibers were phosphated in a tube furnace using sodium hypophosphite as the phosphorus source. The heating rate was 2°C / min, the phosphate temperature was 350°C, the phosphate time was 5 hours, and the mass ratio of sodium hypophosphite to carbonized fibers was 1:15. The diameter of the obtained nickel-iron bimetallic multi-component composite porous fiber material was approximately 200 nm (e.g., Figure 1 Its composition is FeNi3N (12.2%), FeNi2P (18.1%), FeNi3 (21.3%) and NCF (48.4%). Figure 2 Its specific surface area is 306.9 m². 2 / g ( Figure 3 The pore volume is 0.48 cm. 3 / g ( Figure 4 ).

[0043] (3) Catalytic performance test

[0044] Test Method: 5.0 mg of the prepared catalyst was weighed and added to a solution of 0.45 mL anhydrous ethanol and 5 μL Nafion (DuPont, 5 wt%). The mixture was sonicated for 20 min, and 6 μL of the suspension was coated onto a 3 mm glassy carbon electrode. Using the prepared glassy carbon electrode as the working electrode, a graphite electrode as the counter electrode, an Ag / AgCl electrode as the reference electrode, and 1.0 M KOH as the electrolyte, HER and OER tests were performed in a three-electrode system. For the water electrolysis performance test, a two-electrode system was used. The prepared suspension was drop-coated onto two pieces of nickel foam (coating area 1 cm × 1 cm), with a catalyst loading of 0.5 mg / cm². 2 Positive and negative electrodes were fabricated and tested in a 1.0 M KOH solution. Stability testing was performed at a current density of 10 mA / cm². 2This method involves testing the current-time curve at the corresponding potential. Stability is expressed as the percentage decrease in current density (i.e., relative current density) versus time.

[0045] Test results: at a current density of 10 mA / cm² 2 At that time, the overpotential for catalytic HER was 128 mV ( Figure 5 The overpotential for catalytic OER is 222 mV. Figure 6 The decomposition voltage of catalytic water electrolysis is 1.56 V (10 mA / cm). 2 hour)( Figure 7 After a 10-hour stability test, the catalyst's current density decreased by only 19.6%. Figure 8 These results demonstrate that the catalyst exhibits excellent activity and stability in catalyzing HER, OER, and water electrolysis.

[0046] Example 2

[0047] (1) Preparation of precursor: 4.0 g PAN, 8.0 g phenylenediamine Schiff base, 0.606 g (1.5 mmol) Fe(NO3)3·9H2O and 1.744 g (6.0 mmol) Ni(NO3)3·6H2O were dissolved in 100 mL DMF to form a transparent solution. The mass ratio of PAN to phenylenediamine Schiff base was 1:2, the molar ratio of iron salt to nickel salt was 1:4, and the mass ratio of PAN + phenylenediamine Schiff base to solvent DMF was 1:8. The solution was transferred to a syringe, and the precursor was prepared by electrospinning at a flow rate of 1.5 mL / h and a voltage of 16.5 kV. The distance between the collecting plate and the needle was 18 cm.

[0048] (2) Preparation of nickel-iron bimetallic multi-component composite porous fiber material: The precursor prepared in (1) was first heat-treated in a tube furnace at 800 °C for 4 h under N2 atmosphere, with a heating rate of 4 °C / min, to generate carbonized fibers through carbothermic reaction. Then, the carbonized fibers were phosphated in a tube furnace using sodium hypophosphite as the phosphorus source. The heating rate was 2 °C / min, the phosphated temperature was 350 °C, the phosphated time was 5 h, and the mass ratio of sodium hypophosphite to carbonized fibers was 1:15. The obtained nickel-iron bimetallic multi-component composite porous fiber material had a diameter of approximately 200 nm, and its composition was FeNi3N (13.5%), FeNi2P (15.9%), FeNi3 (23.7%), and NCF (46.9%), with a specific surface area of ​​286.7 m². 2 / g, pore volume 0.45 cm³ 3 / g.

[0049] (3) Catalytic performance test

[0050] Test method: Same as Example 1.

[0051] Test results: at a current density of 10 mA / cm² 2 At that time, the overpotential for catalytic HER was 183 mV, the overpotential for catalytic OER was 297 mV, and the decomposition voltage for catalytic water electrolysis was 1.59 V (10 mA / cm). 2 (Time). After a 10-hour stability test, the catalyst's current density decreased by only 20.3%.

[0052] Example 3

[0053] (1) Preparation of precursor: 4.0 g PAN, 8.0 g phenylenediamine Schiff base, 0.606 g (1.5 mmol) Fe(NO3)3·9H2O and 0.872 g (3.0 mmol) Ni(NO3)3·6H2O were dissolved in 100 mL DMF to form a transparent solution. The mass ratio of PAN to phenylenediamine Schiff base was 1:2, the molar ratio of iron salt to nickel salt was 1:2, and the mass ratio of PAN + phenylenediamine Schiff base to solvent DMF was 1:8. The solution was transferred to a syringe, and the precursor was prepared by electrospinning at a flow rate of 1.5 mL / h and a voltage of 16.5 kV. The distance between the collecting plate and the needle was 18 cm.

[0054] (2) Preparation of nickel-iron bimetallic multi-component composite porous fiber material: The precursor prepared in (1) was first heat-treated in a tube furnace at 800 °C for 4 h under N2 atmosphere with a heating rate of 4 °C / min to generate carbonized fibers through carbothermic reaction. Then, the carbonized fibers were phosphated in a tube furnace using sodium hypophosphite as the phosphorus source. The heating rate was 2 °C / min, the phosphate temperature was 350 °C, the phosphate time was 5 h, and the mass ratio of sodium hypophosphite to carbonized fibers was 1:15. The obtained nickel-iron bimetallic multi-component composite porous fiber material had a diameter of approximately 180 nm, and its composition was FeNi3N (10.5%), FeNi2P (19.6%), FeNi3 (17.5%), and NCF (52.4%), with a specific surface area of ​​313.5 m². 2 / g, pore volume 0.50 cm³ 3 / g.

[0055] (3) Catalytic performance test

[0056] Test method: Same as Example 1.

[0057] Test results: at a current density of 10 mA / cm² 2At that time, the overpotential for catalytic HER was 132 mV, the overpotential for catalytic OER was 301 mV, and the decomposition voltage for catalytic water electrolysis was 1.61 V (10 mA / cm²). 2 (Time). After a 10-hour stability test, the catalyst's current density decreased by only 18.7%.

[0058] Example 4

[0059] (1) Preparation of precursor: 4.0 g PAN, 4.0 g phenylenediamine Schiff base, 0.606 g (1.5 mmol) Fe(NO3)3·9H2O and 1.308 g (4.5 mmol) Ni(NO3)3·6H2O were dissolved in 100 mL DMF to form a transparent solution. The mass ratio of PAN to phenylenediamine Schiff base was 1:1, the molar ratio of iron salt to nickel salt was 1:3, and the mass ratio of PAN + phenylenediamine Schiff base to solvent DMF was 1:8. The solution was transferred to a syringe, and the precursor was prepared by electrospinning at a flow rate of 1.5 mL / h and a voltage of 16.5 kV. The distance between the collecting plate and the needle was 18 cm.

[0060] (2) Preparation of nickel-iron bimetallic multi-component composite porous fiber material: The precursor prepared in (1) was first heat-treated in a tube furnace at 800 °C for 4 h under N2 atmosphere with a heating rate of 4 °C / min to generate carbonized fibers through carbothermic reaction. Then, the carbonized fibers were phosphated in a tube furnace using sodium hypophosphite as the phosphorus source. The heating rate was 2 °C / min, the phosphate temperature was 350 °C, the phosphate time was 5 h, and the mass ratio of sodium hypophosphite to carbonized fibers was 1:15. The obtained nickel-iron bimetallic multi-component composite porous fiber material had a diameter of approximately 200 nm and its composition was FeNi3N (14.4%), FeNi2P (21.3%), FeNi3 (24.4%), and NCF (39.9%), with a specific surface area of ​​258.6 m². 2 / g, pore volume 0.38 cm³ 3 / g.

[0061] (3) Catalytic performance test

[0062] Test method: Same as Example 1.

[0063] Test results: at a current density of 10 mA / cm² 2 At that time, the overpotential for catalytic HER was 138 mV, the overpotential for catalytic OER was 252 mV, and the decomposition voltage for catalytic water electrolysis was 1.57 V (10 mA / cm). 2 (Time). After a 10-hour stability test, the catalyst's current density decreased by only 21.4%.

Claims

1. A method for preparing a nickel-iron bimetallic multi-component composite porous fiber material, comprising the following process steps: (1) Preparation of precursor: Phenylenediamine Schiff base, polyacrylonitrile, iron salt and nickel salt were dissolved in N,N-dimethylformamide to form a transparent solution. The solution was electrospun at a voltage of 16kV to obtain precursor fibers. The mass ratio of polyacrylonitrile to phenylenediamine Schiff base was 1:1-1:3; the molar ratio of iron salt to nickel salt was 1:2-1:4; the mass ratio of polyacrylonitrile and phenylenediamine Schiff base to solvent N,N-dimethylformamide was 1:8-1:

12. (2) Preparation of nickel-iron bimetallic multi-component composite porous fiber material: The precursor prepared above is first treated in a tube furnace under N2 atmosphere at a rate of 3-5℃ / min to 700-900℃ for 2-6 h to obtain carbonized fiber; the carbonized fiber is then treated in a tube furnace with sodium hypophosphite as phosphorus source at a rate of 1-3℃ / min to 350℃ for 4-8 h to obtain nickel-iron bimetallic multi-component composite porous fiber material.

2. The preparation method of the nickel-iron bimetallic multi-component composite porous fiber material as described in claim 1, characterized in that: In step (1), the iron salt is one of Fe(OH)(CH3COO)2, FeCl3·6H2O, or Fe(NO3)3·9H2O.

3. The preparation method of the nickel-iron bimetallic multi-component composite porous fiber material as described in claim 1, characterized in that: In step (1), the nickel salt is one of Ni(CH3COO)2·4H2O, NiCl2·6H2O, or Ni(NO3)3·6H2O.

4. The preparation method of the nickel-iron bimetallic multi-component composite porous fiber material as described in claim 1, characterized in that: In step (2), the mass ratio of sodium hypophosphite to carbonized fiber is 1:10-1:

20.

5. The preparation method of the nickel-iron bimetallic multi-component composite porous fiber material as described in claim 1, characterized in that: The prepared nickel-iron bimetallic multi-component composite porous fiber material consists of four components: nickel-iron bimetallic nitride FeNi3N, phosphide FeNi2P, alloy FeNi3, and N-doped carbon fiber NCF. The mass fractions of FeNi3N, FeNi2P, FeNi3, and NCF are 9-15%, 12-22%, 15-25%, and 38-64%, respectively. The composite porous fiber material has a diameter of 200 nm and a specific surface area of ​​185-326 m². 2 / g, pore volume 0.35-0.52 cm³ 3 / g.

6. The application of the nickel-iron bimetallic multi-component composite porous fiber material prepared by the method described in claim 1 in the electrocatalytic hydrogen evolution reaction.

7. The application of the nickel-iron bimetallic multi-component composite porous fiber material prepared by the method described in claim 1 in the electrocatalytic oxygen evolution reaction.

8. The application of the nickel-iron bimetallic multi-component composite porous fiber material prepared by the method described in claim 1 in the electrocatalytic water splitting reaction.

Images