CN115000421A - N, Se doped carbon nanofiber loaded CoSe organic framework composite material as well as preparation method and application thereof - Google Patents

N, Se doped carbon nanofiber loaded CoSe organic framework composite material as well as preparation method and application thereof Download PDF

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CN115000421A
CN115000421A CN202210829803.2A CN202210829803A CN115000421A CN 115000421 A CN115000421 A CN 115000421A CN 202210829803 A CN202210829803 A CN 202210829803A CN 115000421 A CN115000421 A CN 115000421A
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CN115000421B (en
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卢惠民
刘建学
卢小溪
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Yihang Times Beijing Technology Co ltd
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    • H01—ELECTRIC ELEMENTS
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    • H01M4/8663—Selection of inactive substances as ingredients for catalytic active masses, e.g. binders, fillers
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    • H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
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Abstract

The invention provides an N, Se doped carbon nanofiber loaded CoSe organic framework composite material, which belongs to the technical field of catalysts and comprises N, Se doped carbon nanofibers and ZIF-67 pyrolytic derived carbon loaded on the surface of N, Se doped carbon nanofibers, wherein CoSe particles are loaded on the surface and inside of the ZIF-67 pyrolytic derived carbon. According to the invention, the ZIF-67 pyrolysis derived carbon is used as a dispersion matrix of the CoSe particles, and the ZIF-67 can realize the atomic-level dispersion of Co, limit the agglomeration of the CoSe particles and improve the oxygen reduction catalytic activity of the CoSe particles. According to the invention, N, Se doped carbon nanofibers are used as a load matrix, so that the carbon nanofibers can be endowed with good conductivity, the conduction of electrons in catalysis is facilitated, and the catalytic reaction is promoted. When the composite material is used as a cathode catalyst of an aluminum air battery, the composite material has good oxygen reduction catalytic activity and can be compared favorably with a Pt/C catalyst.

Description

N, Se doped carbon nanofiber loaded CoSe organic framework composite material and preparation method and application thereof
Technical Field
The invention relates to the technical field of catalysts, and particularly relates to an N, Se doped carbon nanofiber loaded CoSe organic framework composite material as well as a preparation method and application thereof.
Background
The demand of the current society for energy is higher and higher, but the reserves of fossil energy such as coal, oil, natural gas and the like relied on by human are limited, and the energy crisis is more and more severe. In addition, the combustion of the fossil fuel generates a large amount of greenhouse gases, which aggravates the greenhouse effect of the earth and pollutes the environment, so that the development of alternatives of the fossil fuel is urgently needed. Emerging energy sources comprise wind energy, water energy, solar energy, geothermal energy and the like, have the advantages of cleanness, high efficiency, renewability, low cost and the like, have the defects of dispersity, intermittence, poor stability and the like, are difficult to directly utilize, and usually need an energy storage system to be matched with storage for development and utilization.
The metal aluminum air battery has the characteristics of low cost, high theoretical energy density (2.98Ah/g) equivalent to lithium (3.86Ah/g), small environmental pollution and cyclic utilization, is known as '21 st century green energy', and is a powerful substitute for fossil fuel. The catalytic activity of the cathode catalyst is an important factor that directly affects the performance of the aluminum air cell. The most commonly used catalysts with better performance are noble metal catalysts, including platinum, palladium, gold, silver, etc., but their low reserves, high cost and short service life limit their commercial development.
The transition metal-based catalyst has high activity and stability, which causes high attention in the research field. Among them, transition metal selenide (TMSe) material has become a highly efficient catalytic material in recent years due to its unique catalytic and electronic properties. However, the transition metal selenide has a phenomenon of easy agglomeration, and the oxygen reduction catalytic activity is not ideal when the transition metal selenide is directly used as a cathode catalyst of an aluminum air battery.
Disclosure of Invention
In view of the above, the invention aims to provide an N, Se doped carbon nanofiber-supported CoSe organic framework composite material, and a preparation method and an application thereof, and N, Se doped carbon nanofiber-supported CoSe organic framework composite material provided by the invention has good oxygen reduction catalytic activity.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides an N, Se doped carbon nanofiber supported CoSe organic framework composite material which comprises N, Se doped carbon nanofibers and ZIF-67 pyrolytic derivative carbon loaded on the surface of the N, Se doped carbon nanofibers, wherein CoSe particles are loaded on the surface and inside of the ZIF-67 pyrolytic derivative carbon.
Preferably, the molar ratio of Co to Se in the CoSe particles is 0.85: 1;
the CoSe particles account for 10-15% of the N, Se doped carbon nanofiber loaded CoSe organic framework composite material in mass.
Preferably, the mass content of the ZIF-67 pyrolytic derived carbon in the N, Se doped carbon nanofiber loaded CoSe organic framework composite material is 15-35%.
Preferably, the N, Se doped carbon nanofiber loaded CoSe organic framework composite material has a diameter of 0.5-1 μm;
the diameter of the N, Se doped carbon nanofiber is 100-200 nm;
the particle size of the CoSe particles is 5-10 nm.
The invention provides a preparation method of the N, Se doped carbon nanofiber loaded CoSe organic framework composite material, which comprises the following steps:
mixing polyacrylonitrile, a ZIF-67 organic framework material and an organic solvent to obtain an electrostatic spinning precursor solution;
carrying out electrostatic spinning on the electrostatic spinning precursor solution, and drying to obtain a spinning fiber film;
heating and oxidizing the spinning fiber film to obtain a pre-oxidized fiber film;
and mixing the pre-oxidized fiber film with selenium powder, and pyrolyzing to obtain N, Se doped carbon nanofiber supported CoSe organic framework composite material.
Preferably, the mass ratio of the polyacrylonitrile to the ZIF-67 organic framework material is 0.55: 0.15-0.25.
Preferably, the parameters of the electrostatic spinning include:
the positive high voltage is 12.5-13.5 kV;
the negative high voltage is 1.8-2 kV;
the distance between the needle head and the collecting plate is 12-14 cm;
the advancing speed is 0.9-1.1 mLh -1 。
Preferably, the heating and oxidizing temperature is 240-280 ℃, and the heat preservation time is 1-2 h.
Preferably, the mass ratio of the pre-oxidized fiber film to the selenium powder is 1: 2-3;
the pyrolysis temperature is 800-850 ℃, and the heat preservation time is 2-3 h.
The invention provides application of the N, Se doped carbon nanofiber loaded CoSe organic framework composite material as a cathode catalyst of an aluminum-air battery.
The invention provides an N, Se doped carbon nanofiber supported CoSe organic framework composite material which comprises N, Se doped carbon nanofibers and ZIF-67 pyrolytic derivative carbon loaded on the surface of the N, Se doped carbon nanofibers, wherein CoSe particles are loaded on the surface and inside of the ZIF-67 pyrolytic derivative carbon. According to the invention, the ZIF-67 pyrolysis derived carbon is used as a dispersion matrix of the CoSe particles, and the ZIF-67 can realize the atomic-level dispersion of Co and limit the agglomeration of the CoSe particles, so that the oxygen reduction catalytic activity of the CoSe particles is improved. According to the invention, N, Se doped carbon nanofiber is used as a load matrix, since Se has a larger covalent bond length (120pm) and is much larger than C (73pm) and N (71pm), large defect deformation can be introduced into the carbon nanofiber crystal lattice, and charge localization and chemical adsorption to oxygen are accelerated; se atoms can also introduce a pi conjugated system into the carbon nanofiber substrate, so that an efficient electron transfer path is provided for the carbon nanofibers, the interface charge transfer impedance is reduced, the carbon nanofibers are endowed with good conductivity, the conduction of electrons in catalysis is facilitated, and the smooth proceeding of catalytic reaction is promoted. The results of the examples show that the N, Se doped carbon nanofiber loaded CoSe organic framework composite material has good oxygen reduction catalytic activity when used as a cathode catalyst of an aluminum-air battery, and can be compared favorably with a Pt/C catalyst; durability tests show that the initial potential of the composite material provided by the invention is hardly changed under the action of 5000 CV cycles, which indicates that the oxygen reduction reaction activity of the composite material has long-term stability.
The invention provides a preparation method of N, Se doped carbon nanofiber loaded CoSe organic framework composite material, which comprises the steps of carrying out electrostatic spinning on an electrostatic spinning precursor solution containing a ZIF-67 organic framework material, loading the ZIF-67 organic framework material on the surface of the carbon nanofiber, realizing thermal oxygen stabilization through heating oxidation, mixing with selenium powder for pyrolysis, doping part of selenium into the carbon nanofiber in the pyrolysis process, forming CoSe particles by part of selenium and Co in the ZIF-67 organic framework material, and preventing Co from high-temperature migration and agglomeration by the ZIF-67 organic framework material in the selenization process due to the atomic-level dispersion of Co in the ZIF-67 organic framework material, so that the increase of the particle size of the CoSe particles is limited, and the oxygen reduction catalytic activity of the CoSe particles is ensured. In the invention, the selenization and the pyrolysis carbonization reaction are carried out synchronously, which is different from the high-temperature process of carbonization firstly and then selenization in the prior art, thereby shortening the high-temperature process time of the composite material and avoiding the further growth of CoSe particles. Meanwhile, the preparation method provided by the invention is simple to operate, low in cost and suitable for industrial mass production.
Drawings
FIG. 1 is a process for preparing N, Se doped nano carbon fiber supported CoSe organic framework composite material;
FIG. 2 is a micro-topography of ZIF-67;
FIG. 3 is a microscopic morphology of a fiber membrane obtained after pure PAN/DMF system spinning;
FIG. 4 is a microscopic topography of N, Se-CNFs;
FIG. 5 shows Co 0.85 A microtopography of Se/C;
FIG. 6 shows Co 0.85 Se@N,Se-CNFs、N,Se-CNFs、ZIF-67、Co 0.85 XRD pattern of Se/C;
FIG. 7 shows Co 0.85 SEM and TEM scanning test results of Se @ N, Se-CNFs;
FIG. 8 shows Co 0.85 EDS component analysis results and element content proportion of Se @ N, Se-CNFs;
FIG. 9 shows Co 0.85 XPS scans of Se @ N, Se-CNFs;
FIG. 10 shows Co 0.85 The X-ray absorption spectrum of Se @ N, Se-CNFs;
FIG. 11 shows Co 0.85 Of Se latticeAn intuitive model;
FIG. 12 shows Co 0.85 Raman spectra of Se @ N, Se-CNFs;
FIG. 13 shows Co 0.85 N of Se @ N, Se-CNFs samples 2 Adsorption-desorption isotherm curves and BJH pore size distributions;
FIG. 14 shows Co 0.85 A thermal decomposition curve of Se @ N, Se-CNFs and an XRD curve of a decomposition product;
FIG. 15 shows Co 0.85 The test result of the oxygen reduction reaction of Se @ N, Se-CNFs;
FIG. 16 shows a chronoamperometry and CV-cycle method for Co 0.85 Test results of Se @ N, Se-CNFs;
FIG. 17 is a transmission electron microscopy characterization of the durability test specimen;
FIG. 18 is an EDS face scan analysis of durability test samples;
FIG. 19 is a graph of Co vs. functional theory of density 0.85 Analyzing the result of the electrocatalytic reaction process of the Se @ N, Se-CNFs sample;
FIG. 20 shows Co 0.85 Electrochemical impedance test results of Se @ N, Se-CNFs;
FIG. 21 shows Co 0.85 The actual discharge performance test result of the aluminum air fuel cell when Se @ N, Se-CNFs are used as the air cathode catalyst;
FIG. 22 shows two assemblies of Co 0.85 And an aluminum air single cell with Se @ N and Se-CNFs as cathode catalysts is connected in series to light the LED small lamp bead object diagram.
Detailed Description
The invention provides an N, Se doped carbon nanofiber supported CoSe organic framework composite material which comprises N, Se doped carbon nanofibers and ZIF-67 pyrolytic derivative carbon loaded on the surface of the N, Se doped carbon nanofibers, wherein CoSe particles are loaded on the surface and inside of the ZIF-67 pyrolytic derivative carbon.
In the invention, the diameter of the N, Se doped nano carbon fiber is preferably 100-200 nm, and more preferably 150 nm. In the N, Se doped nano carbon fiber, the atomic ratio of Se to C is preferably 1.5-2%, and more preferably 1.6-1.8%. In the invention, since Se has larger covalent bond length (120pm) and is much larger than C (73pm) and N (71pm), large defect deformation can be introduced into the carbon nanofiber crystal lattice, and charge localization and chemical adsorption to oxygen are accelerated; se atoms can also introduce a pi conjugated system into the carbon nanofiber matrix, so that a high-efficiency electron transfer path is provided, and interface charge transfer resistance is reduced. Se atoms with higher polarizability can produce a fast response to reactants in the electrolyte than N, P and S.
In the invention, the mass content of the ZIF-67 pyrolytic derived carbon in the N, Se doped carbon nanofiber loaded CoSe organic framework composite material is preferably 15-35%, and more preferably 20-25%. In the invention, the particle size of the ZIF-67 pyrolysis derived carbon is preferably 140-160 nm, more preferably 150nm, and the ZIF-67 pyrolysis derived carbon has a cubic structure. In the invention, the ZIF-67 pyrolytic derivative carbon is preferably connected in series in a bead-string shape in N, Se doped carbon nanofibers, and the structure can promote the transmission of reactants and accelerate the electrochemical reaction process.
In the present invention, the molar ratio of Co to Se in the CoSe particles is preferably 0.85: 1; the mass content of the CoSe particles in the N, Se doped carbon nanofiber loaded CoSe organic framework composite material is preferably 10-15%, and more preferably 13-14%. In the invention, the particle size of the CoSe particle is preferably 5-10 nm, and more preferably 6-8 nm. In the present invention, the CoSe particles have a hexagonal crystal structure. According to the invention, the ZIF-67 pyrolysis derived carbon is used as a dispersion matrix of the CoSe particles, and the ZIF-67 can realize the atomic-level dispersion of Co and limit the agglomeration of the CoSe particles, so that the oxygen reduction catalytic activity of the CoSe particles is improved.
In the invention, the diameter of the N, Se doped carbon nanofiber supported CoSe organic framework composite material is preferably 0.5-1 μm, and more preferably 0.6-0.8 μm.
The invention provides a preparation method of the N, Se doped carbon nanofiber loaded CoSe organic framework composite material, which comprises the following steps:
mixing polyacrylonitrile, a ZIF-67 organic framework material and an organic solvent to obtain an electrostatic spinning precursor solution;
carrying out electrostatic spinning on the electrostatic spinning precursor solution, and drying to obtain a spinning fiber film;
heating and oxidizing the spinning fiber film to obtain a pre-oxidized fiber film;
and mixing the pre-oxidized fiber film with selenium powder, and carrying out pyrolysis to obtain N, Se doped carbon nanofiber loaded CoSe organic framework composite material.
The invention mixes polyacrylonitrile, ZIF-67 organic framework material and organic solvent to obtain electrostatic spinning precursor solution. In the present invention, the molecular weight of Polyacrylonitrile (PAN) is preferably 140000 to 150000. In the present invention, the organic solvent is preferably Dimethylformamide (DMF).
In the invention, the organic ligand of the ZIF-67 organic framework material is 2-methylimidazole, and the coordination ions are cobalt ions. In the present invention, the preparation method of the ZIF-67 organic framework material preferably comprises the following steps:
and mixing soluble divalent cobalt salt, 2-methylimidazole, a surfactant and water, and carrying out a coordination reaction to obtain the ZIF-67 organic framework material.
In the present invention, the surfactant is preferably cetyltrimethylammonium bromide (CTAB). In the present invention, the soluble divalent cobalt salt is preferably cobalt nitrate; the molar ratio of the soluble divalent cobalt salt to the 2-methylimidazole is preferably 1: 70-80, and more preferably 1: 75.
In the present invention, the temperature of the coordination reaction is preferably room temperature, and the time is preferably 1 hour.
In the invention, the mass ratio of polyacrylonitrile to the ZIF-67 organic framework material is preferably 0.55: 0.15-0.25, and more preferably 0.55: 0.2. In the invention, the mass concentration of polyacrylonitrile in the electrostatic spinning precursor solution is preferably 10-12%, and more preferably 11%. In the present invention, the ZIF-67 surface has a large amount of metal ions capable of bonding to the-C.ident.N group contained in PAN therein when added to the PAN/DMF system.
After the electrostatic spinning precursor solution is obtained, the electrostatic spinning precursor solution is subjected to electrostatic spinning and dried to obtain the spinning fiber film. In the present invention, the parameters of the electrospinning preferably include:
the positive high voltage is preferably 12.5-13.5 kV, and more preferably 13 kV;
the negative high voltage is preferably 1.8-2 kV, and more preferably 1.9 kV;
the distance between the needle head and the collecting plate is preferably 12-14 cm, and more preferably 13 cm;
the preferable propelling speed is 0.9-1.1 mL h -1 More preferably 1mL h -1 。
In the invention, the drying temperature is preferably 60-80 ℃, and more preferably 70 ℃; the time is preferably 10 to 12 hours, and more preferably 11 hours.
After the spinning fiber film is obtained, the invention heats and oxidizes the spinning fiber film to obtain the pre-oxidized fiber film. In the present invention, the atmosphere of the thermal oxidation is preferably an air atmosphere. In the invention, the temperature of the heating oxidation is preferably 240-280 ℃, and more preferably 260-280 ℃; the heat preservation time is preferably 1-2 h, and more preferably 1.5 h. In the present invention, the rate of temperature rise to the heating oxidation temperature is preferably 1 to 3 ℃/min, and more preferably 2 ℃/min. In the invention, after electrostatic spinning film formation, preoxidation is carried out in an aerobic atmosphere, cyclization and other reactions can occur, chain PAN molecules are converted into a heat-resistant ladder-shaped structure, and preparation is made for forming a continuous high-quality carbonized film in subsequent carbonization.
After the pre-oxidized film is obtained, the pre-oxidized fiber film is mixed with selenium powder for pyrolysis, and the N, Se doped carbon nanofiber supported CoSe organic framework composite material is obtained. In the invention, the mass ratio of the pre-oxidized fiber film to the selenium powder is preferably 1: 2-3, and more preferably 1: 2.5.
In the present invention, the atmosphere for the pyrolysis is preferably H 2 Mixed gas with Ar, H in the mixed gas 2 The volume content of (b) is preferably 5 to 7%, more preferably 6%. In the invention, the pyrolysis temperature is preferably 800-850 ℃, and more preferably 820-840 ℃; the heat preservation time is preferably 2-3 h, and more preferably 2.5 h. In the present invention, the rate of temperature rise to the pyrolysis temperature is preferably set to1 to 3 ℃/min, more preferably 2 ℃/min. According to the invention, through the pyrolysis, PAN fiber in the pre-oxidation film is converted into carbon fiber, and the ZIF-67 organic framework material is converted into ZIF-67 pyrolysis derived carbon. Meanwhile, in the pyrolysis process, the selenium powder is changed into steam, so that selenium doping of the carbon fiber and generation of CoSe particles are realized.
The preparation process of the N, Se doped nano carbon fiber loaded CoSe organic framework composite material is shown in figure 1.
The invention provides an application of the N, Se doped nano carbon fiber loaded CoSe organic framework composite material or an aluminum-air battery cathode catalyst. The composite material provided by the invention can avoid the agglomeration of CoSe particles and has good oxygen reduction catalytic activity.
The N, Se doped nano carbon fiber supported CoSe organic framework composite material provided by the invention and the preparation method and application thereof are explained in detail with reference to the examples below, but the invention is not to be construed as being limited by the scope of the invention.
Example 1
(1) Preparation of cubic ZIF-67: 700mg of Co (NO) 3 ) 2 ·6H 2 O and 5mg CTAB were dissolved in 10mL of deionized water, then 15g of 2-methylimidazole were dissolved in 100mL of deionized water, and then the two were mixed well and stirring was continued at room temperature for 1 h. Then, centrifugal dehydration is carried out, and the obtained purple powder is washed for 3 times and dried for standby.
(2) Preparing a spinning precursor solution; 0.55g of PAN was dissolved in 5.5mL of DMF with stirring and thoroughly stirred until it was uniform and transparent, followed by addition of 0.2g of ZIF-67.
(3) Preparing an electrostatic spinning film: the purple precursor solution was introduced into a 10mL plastic syringe and electrospun. The positive high voltage of 13kV and the negative high voltage of 1.9kV are set. The distance between the needle head and the collecting plate is kept at 13cm, and the advancing speed is 1mL h -1 And after spinning is finished, the film is put into a drying oven to be dried for 10 hours at the temperature of 60 ℃ for standby.
(4) Pre-oxidation and pyrolysis: transferring the electrostatic spinning film into a glass tube of a tube furnace, raising the temperature from room temperature to 280 ℃ at the speed of 2 ℃/min under the air atmosphere, and preserving the heat for 1h to finish the thermal oxidation stabilityAnd (5) a customizing process. And then carrying out high-temperature pyrolysis on the pre-oxidation film and the selenium powder together, wherein the mass ratio of the pre-oxidation film to the selenium powder is 1: 2.5. Setting high temperature atmosphere as H 2 Ar (5 vol.%), heating to 800 ℃ at a heating rate of 2 ℃/min, and keeping the temperature for 2h to obtain N, Se doped carbon nanofiber loaded CoSe organic framework composite material, which is recorded as Co 0.85 Se@N,Se-CNFs。
And (3) omitting the addition of ZIF-67 in the step (2), and obtaining N, Se doped carbon nanofibers which are marked as N, Se-CNFs with the same operation.
Mixing ZIF-67 with selenium powder, and carrying out high-temperature pyrolysis according to the mode in the step (4) to obtain a CoSe organic framework pyrolytic carbon material, which is marked as Co 0.85 Se/C。
Structural characterization
The micro-topography of the ZIF-67 is shown in FIG. 2. As can be seen, ZIF-67 has a cubic structure.
The microstructure of the fiber membrane obtained after pure PAN/DMF system spinning is shown in figure 3, the microstructure of N, Se-CNFs is shown in figure 4, and Co is 0.85 The microscopic topography of Se/C is shown in FIG. 5.
Co 0.85 Se@N,Se-CNFs、N,Se-CNFs、ZIF-67、Co 0.85 The XRD pattern of Se/C is shown in FIG. 6, (a) is Co 0.85 XRD curves of Se @ N, Se-CNFs, N, Se-CNFs and ZIF-67; (b) is Co 0.85 XRD profile of Se/C. As can be seen from FIG. 6, the ZIF-67 prepared by the present invention was confirmed to be ZIF-67 particles, as compared to the standard card peak spectrum; the diffraction peak of the N, Se-CNFs at 24 ° corresponds to the (002) peak of the graphitized carbon-based material; co 0.85 Se @ N, Se-CNFs and Co 0.85 The diffraction peaks of Se/C at 33.2 °, 44.9 °, 50.4 °, 60.3 ° and 61.8 ° corresponding to the (101), (102), (110), (103) and (201) planes in PDF #04-8806 prove that the material indeed contains hexagonal Co 0.85 Se。
Co 0.85 SEM and TEM scan test results of Se @ N, Se-CNFs are shown in FIG. 7. The picture a in FIG. 7 is an SEM image of an electrospun film mixed with ZIF-67, and it can be seen that ZIF-67 particles are successfully concatenated by PAN fibers during spinning to form a network morphology of interweaving and staggering. Through thermal oxidation stabilization and mixed selenium high-temperature pyrolysis, the productTo obtain Co 0.85 An SEM picture of Se @ N, Se-CNFs is shown in figure 7 b, and the size of the cubic carbonized particle derived from the ZIF-67 at high temperature is about 150nm, which is consistent with the size of the particle obtained by pyrolysis of the pure ZIF-67 mixed selenium powder in figure 5; and under the coating of PAN, the cubic particles derived from ZIF-67 at high temperature have more regular shapes. The particles are interwoven in series by PAN-derived high aspect ratio 1D carbon fibers into a 3D network-like structure; the structure can promote the transmission of reactants and accelerate the progress of electrochemical reaction. C in FIG. 7 shows Co 0.85 TEM image of Se @ N, Se-CNFs, and selective area diffraction pattern thereof proves that the material contains hexagonal Co 0.85 The cubic shape derived from the ZIF-67 can be clearly seen in the Se crystal, and the ZIF-67 does not collapse to a large extent under the wrapping effect of PAN during high-temperature pyrolysis. The face exposed at the edge of the fiber may experience a greater amount of deformation collapse due to the lesser amount of PAN coating. Therefore, the basic morphology of the ZIF-67 can be kept from being excessively aggregated and grown when the ZIF-67 collapses, and more active particles can be exposed outwards to provide more catalytic reaction active sites for electrochemical reactions. In FIG. 7 d is Co 0.85 HRTEM image of Se @ N, Se-CNFs shows the microscopic morphology of particles in the cubic body in the fiber, and the analysis shows that the interplanar spacing is 0.27nm and the particle belongs to Co 0.85 The (101) crystal plane of Se crystal. In FIG. 7 e is Co 0.85 SEM picture of Se @ N, Se-CNFs. In FIG. 7 f is Co 0.85 The C, Co, N and Se elements of Se @ N and Se-CNFs are subjected to surface scanning, and it can be seen that C is the matrix component of the sample, N is mainly distributed on the carbon matrix, Co and Se are mainly distributed in cubic particles, and the Se content of the fiber part is relatively low. This is mainly due to the fact that Co is only present in the high temperature derived cubes of ZIF-67, and Co is formed during pyrolysis 0.85 After Se, the Se element content in the cube is higher. The Se atoms have larger diameters and can not enter the carbon matrix in a large amount, so the content of the carbon fiber is less.
Co 0.85 The EDS component analysis results of Se @ N, Se-CNFs are shown in FIG. 8, for example, in relation to the element content. As can be seen from FIG. 8, the atomic ratio of Co to Se in the material is about 88.78%, compared with Co 0.85 The theoretical atomic ratio of 0.85:1 in Se is very close. These are divided intoThe results of the analyses are also mutually corroborated with the XRD profile analysis.
Co 0.85 XPS scans of Se @ N, Se-CNFs are shown in FIG. 9, (a) full spectrum scans, (b) C1s, (C) N1 s, (d) Co 2p, and (e) Se 3 d. As can be seen from FIG. 9, Co 0.85 The Se @ N, Se-CNFs only contain Co, Se, C, N and O atoms. The high resolution peak of C1s is formed by overlapping C-C, C ═ C, C-N, C-Se, which indicates that N and Se atoms are successfully doped in the carbon matrix. The high resolution peak of N1 s can be subdivided into pyridine N, pyrrole N, graphite N, and N-oxide containing groups. These modified N atoms can increase the conductivity of the matrix and increase the number of reactive sites. Co 2p can be found to contain Co after peak separation 2+ And Co 3 + Ions, which are the very active centers in the catalytic reaction. In the Se 3d high resolution peak, Se-C/O bonds and Co 3p peaks are obviously seen. The appearance of the Se-C/O bond indicates that Se was successfully doped into the carbon matrix, in concert with the C-N bond in C1 s. Se has a larger covalent bond length (120pm), much larger than C (73pm) and N (71pm), and can introduce large defect distortions into the carbon lattice, accelerating charge localization and chemisorption of oxygen. The modified Se atom can also introduce a pi conjugated system into a carbon matrix, so that a high-efficiency electron transfer path is provided, and the interface charge transfer resistance is reduced. Se atoms with higher polarizability can produce a fast response to reactants in the electrolyte than N, P and S.
Co 0.85 The X-ray absorption spectrum of Se @ N, Se-CNFs is shown in FIG. 10, and in FIG. 10, the K-edge normalized X-ray absorption near-edge structures of Co (a) and Se (b); FT-EXAFS spectrograms of Co (c) and Se (d) corresponding to the K-edge near-edge absorption spectrum; extended X-ray attenuating structures of Co (e) and Se (f). Co 0.85 The X-ray near-edge structure of the Co element K edge in Se @ N, Se-CNFs is shown as a in FIG. 10, and the data of 4 standard samples are compared: co 3 O 4 、Co 2 O3, CoO and Co foil, Co being clearly visible 0.85 The edge-front structure of the Se @ N, Se-CNFs samples located on the Co foil (Co0) can be assigned to the Co-N/C and Se-N/C coordination, respectively. This also indicates that Co 0.85 This strong bond exists between Se and the carbon matrix. In addition, the least squares curve (e in FIG. 10 and f in FIG. 10) shows CoAnd fitting results of the K-edge structure of Se. Co and Se atoms can be analyzed in Co by fitting 0.85 And the structure configuration in the Se @ N and Se-CNFs sample. The fitting results of the Co element K while expanding the X-ray absorption fine structure are shown in table 1, and the fitting results of the Se element K while expanding the X-ray absorption fine structure are shown in table 2.
TABLE 1 Co element K edge extension X-ray absorption fine structure fitting results
Figure BDA0003745356750000101
TABLE 2 fitting results of Se element K edge extension X-ray absorption fine structure
Figure BDA0003745356750000111
Note: in tables 1 and 2, N is the coordination number, R is the atomic distance, σ 2 Is a disorder factor, Δ E 0 The energy origin is shifted, and R-factor is the root mean square fit difference (i.e., R factor) between the test values and the fit values.
As shown in tables 1 and 2, the calculated value of the coordination number (Co-Se bond) of Co atom is 2.9, which is higher than that of Se atom (2.8, Se-Co bond), confirming that the sample Co atom is Co 0.85 Cationic vacancies are present in Se @ N, Se-CNFs.
In summary, Co 0.85 Ordered Co vacancies, Co, are present in Se @ N, Se-CNFs 0.85 A visual model of the Se lattice can be seen in fig. 11, where the red spheres show the positions of the vacancies in the lattice.
Co 0.85 The Raman spectrum of Se @ N, Se-CNFs is shown in FIG. 12. In FIG. 12, Co-Se bonds are visible at 190.73, 476.42, 513.55 and 675cm -1 Characteristic peaks appear. And at 1354.6cm -1 (peak D) and 1593.2cm -1 The presence of the (G peak) indicates the presence of a graphitized carbon skeleton in the sample. The intensity ratio of the D peak to the G peak was 1.89 (ID/IG), indicating that Co was present 0.85 A large number of disordered carbon atoms and defects exist in a graphitized carbon structure in the Se @ N, Se-CNFs sample. The graphitized structure can enhance the overall conductivity of the sample and accelerate CoActivity of Se clusters in the reaction.
Co 0.85 N of Se @ N, Se-CNFs samples 2 The adsorption-desorption isotherm curves and BJH pore size distributions are shown in FIG. 13, where a in FIG. 13 is Co 0.85 N of Se @ N, Se-CNFs 2 The adsorption-desorption isotherm curve, and b is a BJH pore size distribution curve. The specific surface area was calculated to be 153.10m 2 g -1 (ii) a The pore diameters of the composite material are distributed on different grades, including micropores and mesopores, and the pore diameter distribution of most of the pores is less than or equal to 4 nm. Such a hierarchical structure enables access to more electrolyte, thereby exposing more active sites, which may promote rapid progress of the oxygen reduction reaction.
To Co 0.85 The Se @ N, Se-CNFs samples were subjected to thermogravimetric analysis, i.e. heating from room temperature to over 800 ℃ in an air atmosphere, to obtain their thermal decomposition profile and decomposition product XRD profile, as shown in fig. 14. In FIG. 14, a is Co 0.85 And a TGA curve of Se @ N, Se-CNFs in an air atmosphere at high temperature, and a XRD curve of a decomposition product. As can be seen from FIG. 14, Co 0.85 The loss of the Se @ N, Se-CNFs sample is little below 300 ℃, which is probably caused only by small molecule gas or water adsorbed on the surface of the sample; the weight of the sample is sharply reduced to below 30% at 300-500 ℃, and the main carbide material of the sample can be combusted to generate CO 2 Escapes; while at higher temperatures up to 800 c the sample eventually formed a black powder. In order to confirm the phase structure of the powder, X-ray scanning was performed, and the obtained curve is shown in FIG. 14b, which belongs to Co 3 O 4 (PDF # 43-1003). It can be seen that Co is heated to 800 deg.C 0.85 Se reacts in high-temperature air to generate Co 3 O 4 Residual 24.75 wt.%. Estimated from this, Co 0.85 Co in Se @ N, Se-CNFs samples 0.85 Se content 13.26 wt.%.
Example 2 Co 0.85 Electrochemical test of oxygen reduction catalytic activity of Se @ N, Se-CNFs composite material
(1)Co 0.85 Oxygen reduction reaction test of Se @ N, Se-CNFs
To further test Co 0.85 Se@N,Se-CNFs，N,Se-CNFs，Co 0.85 The electrochemical performance of Se/C and Pt/C, the invention firstly usesThe same experimental parameters test the CV curves of the samples in an oxygen saturated 0.1M KOH solution and the results are shown in figure 15. In FIG. 15, a is Co 0.85 Se@N,Se-CNFs、Co 0.85 Se/C, N, CV curves of Se-CNFs and Pt/C, b is Co 0.85 Se@N,Se-CNFs、Co 0.85 Se/C, N, LSV curve of Se-CNFs and Pt/C at 1600rpm, C is Co 0.85 LSV curve of Se @ N, Se-CNFs at the rotating speed of 400-1600 rpm, and d is according to Co 0.85 Fitting curve of K-L equation collected by LSV curve of Se @ N, Se-CNFs and number N of transferred electrons. In FIG. 15, a is a clear oxygen reduction peak, especially Co 0.85 Se @ N, Se-CNFs, whose peak lies at 0.85 RHE, even exceeding the reduction peak-to-peak value of Pt/C. And Co 0.85 The peak voltage of the oxygen reduction peak shown on the CV curve of Se/C, N and Se-CNFs is lower, and the peak current is much smaller.
To explore Co deeply 0.85 The reaction process of Se @ N and Se-CNFs samples in oxygen reduction catalysis is that RDE tests are developed on the samples prepared into thin film electrodes under multiple rotating speeds, limiting currents corresponding to different potentials are calculated according to a K-L equation, and oxygen reduction reaction kinetic parameters are analyzed by utilizing a fitting curve of the limiting currents, wherein the parameters are shown as b-d in figure 15. As can be seen from b in FIG. 15, Co was present in an oxygen saturated 0.1M KOH solution at 1600rpm 0.85 The LSV curve starting voltage of the Se @ N, Se-CNFs sample is 0.93V, the half-wave potential is 0.87V, and the performance is slightly higher than that of Pt/C (the starting potential is 0.92V, and the half-wave potential is 0.84V).
As can be seen from c in FIG. 15, Co is present at 400 to 2500rpm 0.85 The initial potential of the Se @ N, Se-CNFs sample is basically constant at 0.93V, and the limiting diffusion current is continuously increased along with the increase of the rotating speed.
Using these curve data, a straight line can be fitted to calculate the path (4 e-path or 2 e-path) of the sample that the catalytic reaction takes place during the oxygen reduction process, based on the K-L equation - A path). From the analysis of d in FIG. 15, at 0.3V, 0.4V, 0.5V and 0.6V, the calculated n values were 3.88, 3.91, 3.89 and 3.95 respectively, and it was found that the oxygen reduction reaction process was 4e - A path.
(2)Co 0.85 Durability test of Se @ N, Se-CNFs
The durability of the oxygen reduction catalyst is critical in determining the cathode life of aluminum air cells, which in turn affects the practical performance and cost of the cell. Therefore, the invention adopts a chronoamperometry and a CV cycling method to treat Co 0.85 The Se @ N, Se-CNFs samples were tested, and the results are shown in FIG. 16, wherein a is Co in FIG. 16 0.85 I-t curves for Se @ N, Se-CNFs and Pt/C; b is Co 0.85 LSV curves at 1600rpm for Se @ N, Se-CNFs were compared before and after 5000 CV cycles.
It can be seen from a in FIG. 16 that Co is present in the oxygen reduction process for 10 hours 0.85 The current of the reaction catalyzed by the Se @ N, Se-CNFs sample is only slowly lost by 2.8% at the beginning of the reaction, which shows that the reaction durability is very high; the Pt/C catalyst is up to 47.6%, the current is greatly reduced at the beginning of the reaction, the subsequent process is stable and is continuously reduced, and the stability of the Pt/C catalyst is not good. In addition, the invention also relates to Co 0.85 Se @ N, Se-CNFs samples were scanned up to 5000 CV cycles and LSV scans before and after to evaluate the effect of 5000 CV cycles of Co 0.85 Decay of the reactivity of Se @ N, Se-CNFs. As shown in b of FIG. 16, the initial potential was almost unchanged, and was slightly shifted in the negative direction, and the limiting diffusion current density was almost the same before and after, and the two curves were considered to be almost the same except for the influence of the uncontrollable factors on the reaction in the test. In summary, Co 0.85 The oxygen reduction reaction activity of Se @ N, Se-CNFs has long-term stability.
Although the durability test proves Co 0.85 The stability of Se @ N, Se-CNFs is very good, but these data only show that the reduction current of the sample catalytic reaction is hardly changed. In order to investigate whether the chemical components and the microscopic appearance of the sample are influenced by the reaction to generate changes, the sample subjected to the durability test is subjected to transmission electron microscope characterization, and the transmission electron microscope characterization is shown in FIG. 17. In FIG. 17, a is Co 0.85 TEM image and diffraction pattern, bCo, of Se @ N, Se-CNFs after durability test 0.85 HRTEM image of Se @ N, Se-CNFs after durability test.
In FIG. 17, a shows TEM image of the sample after the durability test, and it can be seen that the material is still fiber-series-connectedThe structure of a cube. The selected area diffraction pattern of which is designated as Co 0.85 Diffraction rings of (101), (102) and (110) planes of Se. While b in FIG. 17 shows an image of the crystals in the sample cube, it was found by measurement that the interplanar spacing was about 0.27nm, which is attributed to Co 0.85 The (101) plane of Se.
To further characterize the composition and distribution in the fiber structure of the durability test samples, the present inventors further performed EDS surface scan analysis thereon, as shown in fig. 18. It can be seen that the Co element, Se element and C element are mainly distributed in the cubic body of the fiber on the fiber outside the cubic body, and the N element is distributed almost in the whole fiber range. This is also a good demonstration that the material retains the Co content in the carbon fiber loaded cubic particles before the oxygen reduction durability test 0.85 The structure and the component distribution of Se are not changed. Visible Co 0.85 Se @ N, Se-CNFs have very good oxygen reduction reaction durability, and the components are still unchanged and the structure is stable after long-time testing.
(3)Co 0.85 Theoretical calculation research on Se @ N, Se-CNFs activity
To explore Co deeply 0.85 The invention relates to an oxygen reduction reaction active site of a Se @ N, Se-CNFs sample, which utilizes a density functional theory to react Co 0.85 The electrocatalytic reaction process of the Se @ N, Se-CNFs sample is subjected to corresponding theoretical calculation, discussion and analysis, and is shown in FIG. 19. In theoretical computational analysis, the present invention mainly discusses various oxygen reduction reaction active sites possibly existing in the sample, including: 1) n-containing active sites in the pure N, Se-CNFs nanofibers; 2) co active sites in pure CoSe nanoparticles; 3) co0 .85 Active sites containing N in Se @ N, Se-CNFs; 4) co 0.85 Se-containing active sites in Se @ N, Se-CNFs; 5) co 0.85 Se @ N, Co active sites in Se-CNFs. And then calculating and discussing the free energy change course of the oxygen reduction process of the active centers of the electrocatalytic reaction, and analyzing and considering that the main process is as follows: + O2 → + OOH → + O → OH, as shown in a of fig. 19. Wherein eta ORR Is an over potential (η) ORR ＝1.23V-E ORR ) The smaller the value, the higher the oxygen reduction reaction activity of the catalyst material.The numerical analysis shows that Co 0.85 Co in Se @ N, Se-CNFs samples 0.85 The Se outermost Co atom is the most active site for catalytic reaction, and the reaction mechanism model can be seen as a in FIG. 19. This work also compared Co by numerical analysis, as shown in FIGS. 19 b-d 0.85 The oxygen reduction reaction activity of the surfaces of 3 different materials of Se @ N, Se-CNFs, N, Se-CNFs and CoSe (001), and the result shows that the eta of the CoSe material ORR After the combination of CoSe and N, Se-CNFs, the combination is reduced from 0.45V to 0.36V, and the root of the combination probably lies in the speed-controlling step OH of oxygen reduction reaction in Co 0.85 Surface Co of Se @ N, Se-CNFs 0.85 The Co atom of Se undergoes an OH step with a lower free energy than pure CoSe (001).
In order to further study how the synergistic effect of the CoSe particles and the N, Se-CNFs in the oxygen reduction reaction is to improve the electrocatalytic reaction performance, the invention continues to calculate and analyze Co 0.85 The state Density (DOS) and charge density differences of the Se @ N, Se-CNFs and pure CoSe surfaces are used to explore the changes generated by the electronic structures of the materials before and after the introduction of the N, Se-CNFs, as shown in e in FIG. 19. The numerical results demonstrate that indeed the adsorption energy of the CoSe surface to OH is significantly reduced after the introduction of N, Se-CNFs into CoSe. The decrease in the adsorption energy can be attributed to Co 0.85 Co in Se @ N, Se-CNFs 0.85 The electronic energy level of the Co atom 3d layer within Se is closer to the fermi level. In conclusion, the combination of N, Se-CNFs can remarkably reduce the adsorption free energy of the sample in the oxygen reduction reaction and enhance the activity of the oxygen reduction reaction, so that Co in 3 materials 0.85 The electrocatalytic reaction activity of Se @ N and Se-CNFs is highest.
(4)Co 0.85 Impedance studies of Se @ N, Se-CNFs
To deeply analyze Co 0.85 The charge transfer capacity of Se @ N, Se-CNFs samples in the reaction is tested by electrochemical impedance test, and the N, Se-CNFs and Co are compared 0.85 Se/C samples as shown in FIG. 20. Visible Co 0.85 The reaction interface charge transfer impedance of Se @ N and Se-CNFs is minimum, so that the catalytic reaction is facilitated, and the oxygen reduction activity of the sample is improved. Due to Co 0.85 The Se @ N, Se-CNFs sample is prepared from Co 0.85 Se-bonded carbon nanofibers, as compared to ZIF-67 derived carbon particles, carbon fibersThe dimension has a higher electron transport capability and thus a minimum charge transfer resistance. The electrochemical impedance of the solid-liquid interface of the N, Se-CNFs in the reaction is the largest. Co 0.85 Electrochemical impedance of Se/C is in Co 0.85 Se @ N, Se-CNFs and N, Se-CNFs.
Example 3 Co 0.85 Application of Se @ N, Se-CNFs aluminum air battery
To detect Co 0.85 The actual discharge performance of the aluminum air fuel cell when the sample of Se @ N, Se-CNFs was used as an air cathode catalyst, and the redox performance of the catalyst was tested by using a single cell test mold, and the result is shown in FIG. 21. In FIG. 21, a is fabricated Co 0.85 The principle sketch of an aluminum air battery with Se @ N and Se-CNFs as cathode catalysts; b is 50mA cm at room temperature -2 Co at discharge 0.85 Se@N,Se-CNFs、Co 0.85 The discharge capacity of Se/C or Pt/C assembled aluminum-air cells; c-f assembling Co at different temperatures 0.85 Dynamic constant current discharge polarization curve of aluminum air battery with Se @ N, Se-CNFs as cathode catalyst: wherein c is 20-50 ℃, d is 0 ℃ or 10 ℃, e is-20 ℃ or-10 ℃, and f is-40 ℃ or-30 ℃; g-h are Co assembly at different temperatures 0.85 Voltage/power density versus current density curves for aluminum air cells with Se @ N, Se-CNFs as cathode catalysts: wherein g is-20 to 50 ℃, h is-40 ℃ or-50 ℃; i is the single cathode of the aluminum air battery with 50mA cm -2 The variation curve of voltage and power density in the process of switching multiple aluminum anodes during discharge is shown in the inset of Co 0.85 The performances of Se @ N, Se-CNFs are compared with that of Pt/C catalysts.
As can be seen from FIG. 21, at 50mA cm -2 The current density of the anode is constant current discharge until the anode aluminum sheet is completely exhausted, and the obtained discharge curve and the corresponding capacity can be shown as b in figure 21. With Co 0.85 When the Se @ N, Se-CNFs sample is used as an air cathode catalyst, the constant current discharge polarization curve is relatively stable, the voltage is stabilized at 1.2V, and the discharge capacity is 2867.13mAh g -1 Approximate theoretical discharge capacity of Al (2980mA h g -1 ) (ii) a When Pt/C is used as the cathode catalyst of the aluminum-air battery, the initial value of the constant current discharge voltage is only slightly higher than 1.1V, the discharge process is continuously reduced, the fluctuation is large,the battery capacity is only 2618.86mAh g -1 . And Co 0.85 When Se/C is used as cathode catalyst, the voltage is initially 1.0V during constant current discharge and is continuously reduced during discharge, and the battery capacity is only 2536.27mAh g -1 . It can be seen that Co is assembled 0.85 The discharge performance of Se @ N, Se-CNFs is obviously superior to that of Pt/C and Co 0.85 Se/C. This again demonstrates towards Co 0.85 After the Se is introduced into N, Se-CNFs, the oxygen reduction performance of the material can be obviously improved, and Co is also shown 0.85 There is a synergy between Se and N, Se-CNFs.
C in FIG. 21 shows Co Assembly 0.85 And the dynamic constant current discharge polarization curve of the aluminum-air battery with Se @ N and Se-CNFs as the oxygen reduction catalyst. When the temperature is 30-50 ℃, the current density is only 1mA cm at the beginning of discharge -2 The time battery voltage is higher than 1.8V; when the current density of constant current discharge is increased in steps, the voltage of the battery is continuously reduced, but the current density reaches 150mA cm -2 When the voltage is in use, the voltage can still be kept above 0.3V. At 20 ℃, the discharge voltage at each current density is significantly reduced; at 140mA cm -2 The voltage is already close to 0.3V. The same trend of decrease also appears in the test at lower temperatures (-40 ℃ to 10 ℃). It can be seen that the decrease in temperature has an increasing effect on the cell, up to-40 deg.C, at 1.3mA cm -2 The voltage is less than 0.2V at the current density of (2). In the long-time discharge process with different current densities, each step maintains a stable discharge platform, so that Co is shown 0.85 Se @ N, Se-CNFs have excellent electrochemical reaction stability. Fig. 21g and 21h show the relationship between the power density, the voltage and the current density at different temperatures in the above discharge process, and it can be seen that the output power density decreases step by step with the decrease of the temperature. The peak value of the power density at 50 ℃ reaches 80mW cm -2 The peak value of the power density at-40 ℃ only reaches 0.7mW cm -2 。
By manually replacing the metal anode, a "mechanical charge" of the aluminum air cell can be achieved, which puts higher demands on the long-life stability of the cathode catalyst. For this reason, the present working stack aluminum-air cell was subjected to a durability test as indicated by i in fig. 21. The same 1 cathode keeps stable voltage in the continuous discharge of 4 different metallic aluminum sheets, and the specific capacity of the anode is very small in floating. The durability of the cathode catalytic reaction is very excellent, and powerful guarantee is provided for the continuous power supply of the aluminum air battery.
FIG. 22 shows a sample of Co 0.85 The two single aluminum air fuel cells which take Se @ N and Se-CNFs as cathode catalysts are connected in series to form the lightened LED small lamp beads, and the catalyst has practical application significance.
To sum up, Co 0.85 The so excellent performance that Se @ N, Se-CNFs as cathode catalyst can impart to aluminum air cells can be attributed to 3 aspects:
1) co with ordered cation vacancies loaded on carbon fibers with a structure of 1D-3D porous hierarchy 0.85 Se；
2) N, Se co-doped carbon body can provide more reaction sites for electrochemical reaction to form powerful synergistic effect;
3) the 1D-3D porous hierarchical structure has small impedance, and provides great convenience for reactant transfer and electron conduction.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. An N, Se doped carbon nanofiber supported CoSe organic framework composite material comprises N, Se doped carbon nanofibers and ZIF-67 pyrolysis derived carbon supported on the surfaces of the N, Se doped carbon nanofibers, wherein CoSe particles are supported on the surfaces and inside of the ZIF-67 pyrolysis derived carbon.
2. The N, Se doped filamentous nanocarbon-loaded CoSe organic framework composite of claim 1, wherein the CoSe particles have a Co to Se molar ratio of 0.85: 1;
the mass content of the CoSe particles in the N, Se doped carbon nanofiber loaded CoSe organic framework composite material is 10-15%.
3. The N, Se doped filamentous nanocarbon-loaded CoSe organic framework composite material as claimed in claim 1, wherein the mass content of the ZIF-67 pyrolytic derived carbon in the N, Se doped filamentous nanocarbon-loaded CoSe organic framework composite material is 15-35%.
4. The N, Se doped filamentous nanocarbon-loaded CoSe organic framework composite of claim 1 or 2, wherein the N, Se doped filamentous nanocarbon-loaded CoSe organic framework composite has a diameter of 0.5 to 1 μm;
the diameter of the N, Se doped carbon nanofiber is 100-200 nm;
the particle size of the CoSe particles is 5-10 nm.
5. The preparation method of the N, Se doped nano carbon fiber loaded CoSe organic framework composite material as claimed in any one of claims 1 to 4, comprising the following steps:
mixing polyacrylonitrile, a ZIF-67 organic framework material and an organic solvent to obtain an electrostatic spinning precursor solution;
carrying out electrostatic spinning on the electrostatic spinning precursor solution, and drying to obtain a spinning fiber film;
heating and oxidizing the spinning fiber film to obtain a pre-oxidized fiber film;
and mixing the pre-oxidized fiber film with selenium powder, and carrying out pyrolysis to obtain N, Se doped carbon nanofiber loaded CoSe organic framework composite material.
6. The preparation method of claim 5, wherein the mass ratio of polyacrylonitrile to ZIF-67 organic framework material is 0.55: 0.15-0.25.
7. The method for preparing according to claim 5 or 6, wherein the parameters of the electrospinning comprise:
the positive high voltage is 12.5-13.5 kV;
the negative high voltage is 1.8-2 kV;
the distance between the needle head and the collecting plate is 12-14 cm;
the propelling speed is 0.9-1.1 mL h -1 。
8. The preparation method according to claim 5, wherein the temperature of the heating oxidation is 240-280 ℃, and the holding time is 1-2 h.
9. The preparation method according to claim 5, wherein the mass ratio of the pre-oxidized fiber film to the selenium powder is 1: 2-3;
the pyrolysis temperature is 800-850 ℃, and the heat preservation time is 2-3 h.
10. Use of the N, Se doped nano carbon fiber-loaded CoSe organic framework composite material of any one of claims 1 to 4 or the N, Se doped nano carbon fiber-loaded CoSe organic framework composite material prepared by the preparation method of any one of claims 5 to 9 as a cathode catalyst of an aluminum-air battery.
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