CN115050975A - Pyridine nitrogen and Fe-N 2 Co-doped carbon nanofiber and preparation method and application thereof - Google Patents
Pyridine nitrogen and Fe-N 2 Co-doped carbon nanofiber and preparation method and application thereof Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 186
- 239000002134 carbon nanofiber Substances 0.000 title claims abstract description 180
- DLGYNVMUCSTYDQ-UHFFFAOYSA-N azane;pyridine Chemical compound N.C1=CC=NC=C1 DLGYNVMUCSTYDQ-UHFFFAOYSA-N 0.000 title claims abstract description 77
- 238000002360 preparation method Methods 0.000 title claims abstract description 29
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 159
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 134
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims abstract description 53
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 30
- 238000010438 heat treatment Methods 0.000 claims abstract description 29
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000007598 dipping method Methods 0.000 claims abstract description 23
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000001301 oxygen Substances 0.000 claims abstract description 21
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 21
- 230000009467 reduction Effects 0.000 claims abstract description 19
- 239000003054 catalyst Substances 0.000 claims abstract description 14
- 238000005229 chemical vapour deposition Methods 0.000 claims abstract description 13
- 239000000758 substrate Substances 0.000 claims abstract description 13
- 239000000446 fuel Substances 0.000 claims abstract description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 56
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 42
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 36
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 claims description 30
- 238000001816 cooling Methods 0.000 claims description 24
- 239000007789 gas Substances 0.000 claims description 24
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 22
- 229910052786 argon Inorganic materials 0.000 claims description 21
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 16
- 229910017604 nitric acid Inorganic materials 0.000 claims description 16
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 13
- 239000012298 atmosphere Substances 0.000 claims description 11
- 238000005530 etching Methods 0.000 claims description 11
- -1 transition metal salt Chemical class 0.000 claims description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- 239000002253 acid Substances 0.000 claims description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 7
- 239000001257 hydrogen Substances 0.000 claims description 7
- 229910052739 hydrogen Inorganic materials 0.000 claims description 7
- 229910021529 ammonia Inorganic materials 0.000 claims description 6
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 6
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims description 6
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 5
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 5
- 229910052723 transition metal Inorganic materials 0.000 claims description 5
- 239000003575 carbonaceous material Substances 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
- 238000005470 impregnation Methods 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims 6
- 238000004321 preservation Methods 0.000 claims 4
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims 3
- 230000001590 oxidative effect Effects 0.000 claims 2
- 230000001476 alcoholic effect Effects 0.000 claims 1
- 230000003197 catalytic effect Effects 0.000 abstract description 13
- 239000000463 material Substances 0.000 abstract description 13
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 abstract description 12
- 238000007788 roughening Methods 0.000 abstract description 11
- 239000002086 nanomaterial Substances 0.000 abstract description 8
- 238000006555 catalytic reaction Methods 0.000 abstract description 5
- 239000000126 substance Substances 0.000 abstract description 3
- 238000005520 cutting process Methods 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 abstract description 2
- 229910052697 platinum Inorganic materials 0.000 abstract description 2
- 239000012266 salt solution Substances 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 77
- 230000007935 neutral effect Effects 0.000 description 57
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 43
- 239000008367 deionised water Substances 0.000 description 42
- 229910021641 deionized water Inorganic materials 0.000 description 42
- 238000005406 washing Methods 0.000 description 41
- 229910002804 graphite Inorganic materials 0.000 description 27
- 239000010439 graphite Substances 0.000 description 27
- 238000001035 drying Methods 0.000 description 23
- 238000000151 deposition Methods 0.000 description 21
- 230000008021 deposition Effects 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 20
- 238000006722 reduction reaction Methods 0.000 description 18
- 238000009210 therapy by ultrasound Methods 0.000 description 17
- 229910052742 iron Inorganic materials 0.000 description 14
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 13
- 238000002791 soaking Methods 0.000 description 13
- 238000000034 method Methods 0.000 description 10
- 238000001179 sorption measurement Methods 0.000 description 10
- DSVGQVZAZSZEEX-UHFFFAOYSA-N [C].[Pt] Chemical compound [C].[Pt] DSVGQVZAZSZEEX-UHFFFAOYSA-N 0.000 description 8
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 6
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 description 4
- 239000012300 argon atmosphere Substances 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- 239000012299 nitrogen atmosphere Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- CLWRFNUKIFTVHQ-UHFFFAOYSA-N [N].C1=CC=NC=C1 Chemical group [N].C1=CC=NC=C1 CLWRFNUKIFTVHQ-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- 239000002121 nanofiber Substances 0.000 description 2
- 125000004433 nitrogen atom Chemical group N* 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010504 bond cleavage reaction Methods 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000013211 curve analysis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000005036 potential barrier Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
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- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000001075 voltammogram Methods 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
- H01M4/9075—Catalytic material supported on carriers, e.g. powder carriers
- H01M4/9083—Catalytic material supported on carriers, e.g. powder carriers on carbon or graphite
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
- H01M4/8882—Heat treatment, e.g. drying, baking
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/10—Fuel cells with solid electrolytes
- H01M8/1009—Fuel cells with solid electrolytes with one of the reactants being liquid, solid or liquid-charged
- H01M8/1011—Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Abstract
The invention belongs to the technical field of fuel cell oxygen reduction catalyst materials, and particularly relates to pyridine nitrogen and Fe-N 2 Codoped carbon nanofiber and a preparation method and application thereof. Firstly, carrying out surface roughening and chemical vapor deposition treatment on a substrate to obtain carbon nanofibers; secondly, carrying out chemical 'cutting' and nitrogen doping on the carbon nano fiber to obtain the pyridine nitrogen-doped carbon nano fiber; finally, dipping the mixture in a ferric salt solution and carrying out heat treatment to form Fe-N 2 To obtain pyridine nitrogen and Fe-N 2 Co-doped carbon nanofibers. The invention effectively increases the active catalytic sites on the carbon nano-fiber by controlling the specific form and the doping amount of the doped element, so that the carbon nano-fiber has oxygen superior to the oxygen of the element non-specific co-doped carbon nano-fiber and commercial platinum carbonThe reduction catalysis performance has better practicability, and provides a new thought and direction for further improving the oxygen reduction catalysis performance of the carbon nano material based catalyst.
Description
Technical Field
The invention belongs to the technical field of fuel cell oxygen reduction catalyst materials, and particularly relates to pyridine nitrogen and Fe-N 2 Codoped carbon nanofiber and a preparation method and application thereof.
Background
Environmental pollution and energy crisis are two major problems faced by the current social development, the active search for an efficient and environment-friendly energy conversion device has profound strategic significance, and a fuel cell has become a research hotspot in the field of clean energy as one of effective means for solving the problems of low combustion power generation efficiency and environmental pollution of fossil fuels. At present, fuel cells often use precious metal materials such as platinum to prepare oxygen reduction catalysts (cathode catalysts) to obtain high catalytic activity, but the precious metals are low in reserves, expensive, short in service life and incapable of being commercialized in a large scale. Therefore, the development of efficient and low cost non-noble metal oxygen reduction catalysts has become a key breakthrough in facilitating the commercial application of fuel cells.
In recent years, most of researches on non-noble metal oxygen reduction catalysts are carbon nanomaterial-based catalysts, wherein metal-nitrogen co-doped carbon nanomaterials show catalytic performance comparable to commercial platinum carbon, and the preparation cost is low, so that the commercialization of fuel cells is possible. At present, most of doping components in carbon nanomaterials are pure element doping, for example, patent No. CN 110010909 a provides a preparation method and application of a cobalt and nitrogen co-doped carbon nanofiber catalyst, patent No. CN 109950562A discloses a preparation method and application of a nickel, cobalt and nitrogen co-doped nanofiber catalyst, the doping of elements in a carbon material is all stopped at an atomic level, and the prepared catalyst can only achieve oxygen reduction performance similar to that of commercial platinum carbon. However, if the doping of the carbon nano-material with element specific morphology can be controlled, and the active catalytic sites of the material are increased through doping, a new idea is provided for further improving the oxygen reduction catalytic performance of the material.
Disclosure of Invention
Aiming at the technical problems that the element doping of the existing carbon nano material stays at the atom layer and the oxygen reduction catalysis performance is poor due to few active catalysis sites, the invention provides pyridine nitrogen and Fe-N 2 Codoped carbon nanofiber and a preparation method and application thereof.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) preparing a carbon material substrate, preferably a carbon paper substrate, etching the carbon paper substrate by a nitric acid solution with the concentration of 0.1-9M, then putting the carbon paper substrate into an alcohol solution of transition metal salt with the concentration of 0.1-18 wt.% for dipping, and then carrying out chemical vapor deposition, namely, the carbon paper substrate after dipping is subjected to flow of 0.1-6L-min -1 Heating to 450-650 ℃ in nitrogen or argon atmosphere, and then introducing the gas with the flow of 0.1-6 L.min -1 Keeping the temperature of the hydrogen for 0.1-4 h, continuously heating to 450-850 ℃, and then introducing the hydrogen with the flow of 0.1-4 L.min -1 And (3) preserving the heat of the carbon source gas for 0.1-4 h, and finally cooling to room temperature to obtain the carbon nanofiber.
(2) Subjecting the carbon nano-fiber obtained in the step (1) to concentration of 10-22 mol.L -1 After the hydrofluoric acid solution is soaked for 0.1-3 h, the flow rate is 0.1-6 L.min -1 Heating to 400-700 ℃ in nitrogen or argon atmosphere, and then carrying out heating at a flow rate of 0.1-4 L.min -1 And (3) keeping the temperature for 0.1-8 h in an ammonia atmosphere, and finally cooling to room temperature to obtain the pyridine nitrogen doped carbon nanofiber.
(3) Dipping the pyridine nitrogen-doped carbon nanofiber obtained in the step (2) in an alcohol solution of ferric salt with the concentration of 0.1-10 wt.%, and then, carrying out the dipping at the flow rate of 0.1-6L-min -1 Heating to 400-700 ℃ in nitrogen or argon atmosphere, preserving heat for 0.1-5 h, cooling to room temperature, and then adding a dilute strong acid solution with the concentration of 0.1-10 wt.% for impregnation to obtain pyridine nitrogenAnd Fe-N 2 Co-doped carbon nanofibers.
Preferably, the transition metal salt in the step (1) is any one of nickel nitrate, iron nitrate and cobalt nitrate; the carbon source gas is any one of propylene, ethylene and methane.
Preferably, the iron salt in the step (3) is ferric nitrate or ferric chloride; the dilute strong acid solution is dilute hydrochloric acid or dilute nitric acid.
Pyridine nitrogen and Fe-N prepared by the preparation method 2 The codoped carbon nanofiber is applied to the fuel cell oxygen reduction catalyst.
The invention has the beneficial effects that:
(1) pyridine nitrogen and Fe-N of the invention 2 The codoped carbon nanofiber is in a regular arrangement state, is not easy to agglomerate, has stronger electron and ion transmission capability and more exposed catalytic active sites, and is beneficial to discharge of water which is a product of an oxygen reduction reaction. The carbon atoms adjacent to pyridine nitrogen in the carbon nanofiber show stronger Lewis alkalinity, and the charge density distribution on the surface of the material is also changed; meanwhile, charge delocalization is caused by introduction of pyridine nitrogen, the adsorption mode of oxygen molecules is changed from end-type adsorption (Pauling adsorption mode) to bridge type adsorption (Yeager adsorption mode), and the bridge type adsorption is parallel diatom adsorption, so that O-O bond energy can be weakened, and further the oxygen reduction reaction is promoted.
(2) Pyridine nitrogen and Fe-N of the invention 2 The iron atom and the nitrogen atom in the co-doped carbon nanofiber form a coordination bond structure (Fe-N) 2 ) The reduction potential barrier of oxygen on the surface of the carbon nano material is reduced, so that a higher initial reduction potential and smaller ring current are obtained, and a catalytic reaction path is optimized; furthermore, Fe-N 2 With empty d z2 The unsaturated electronic structure of the orbit leads to stronger adsorption capacity and higher catalytic activity, and the contraction of Fe-N bonds in the material changes the charge distribution of central iron ions and surrounding carbon atoms, thereby promoting O 2 In Fe-N 2 Adsorption on sites and subsequent O-O bond cleavage, increasing Fe-N 2 Intrinsic activity of the active centerAnd stability.
(3) The invention provides pyridine nitrogen and Fe-N 2 The preparation method of the codoped carbon nanofiber comprises the steps of regulating pyridine nitrogen and Fe-N 2 The doping amount of (A) can avoid Fe-N 2 D of z2 The molecular orbit moves up and down, thereby ensuring the material and O 2 The adsorption force of (2) is proper, so that the subsequent reduction reaction can be normally carried out; by carrying out pyridine nitrogen and Fe-N on the carbon nano fiber 2 And co-doping is performed, the doping form of the N element is controlled, active catalytic sites on the carbon nanofiber are effectively increased, the oxygen reduction catalytic performance of the carbon nanofiber is better than that of Fe/N co-doped carbon nanofiber and 20% Pt/C (commercial platinum carbon), and the carbon nanofiber has better practicability.
(4) Pyridine nitrogen and Fe-N of the invention 2 According to the preparation method of the co-doped carbon nanofiber, the carbon nanofiber material is doped in a specific element form, so that active catalytic sites on the carbon nanofiber material are increased, the carbon nanofiber material has excellent oxygen reduction catalytic performance, and a new thought and direction are provided for further improving the oxygen reduction catalytic performance of the carbon nanofiber-based catalyst.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 shows pyridine nitrogen and Fe-N in single carbon nanofiber according to the present invention 2 Schematic diagram of the forming process of (1).
FIG. 2 shows pyridine nitrogen and Fe-N of example 1 2 XPS spectra of co-doped carbon nanofibers, pyridine nitrogen-doped carbon nanofibers of comparative example 1, and Fe/N co-doped carbon nanofibers of comparative example 2.
FIG. 3 shows pyridine nitrogen and Fe-N of example 1 2 Fe 2p XPS spectra of co-doped carbon nanofibers.
FIG. 4 shows pyridine nitrogen and Fe-N of example 1 2 Co-doped carbon nanofibers and N1 s XPS contrast spectra for comparative 2 pyridine nitrogen doped carbon nanofibers.
FIG. 5 shows pyridine nitrogen and Fe-N of example 1 2 Scanning electron micrographs (a) of the co-doped carbon nanofibers and the surface scanning distribution of the carbon element (b), the nitrogen element (c) and the iron element (d).
FIG. 6 shows pyridine nitrogen and Fe-N of example 1 2 Co-doped carbon nanofibers, pyridine nitrogen-doped carbon nanofibers of comparative example 1, Fe/N co-doped carbon nanofibers of comparative example 2, and linear voltammogram (LSV) of 20% Pt/C (commercial platinum carbon).
FIG. 7 shows pyridine nitrogen and Fe-N of example 1 2 I-t curves for co-doped carbon nanofibers, pyridine nitrogen doped carbon nanofibers of comparative example 1, Fe/N co-doped carbon nanofibers of comparative example 2, and 20% Pt/C (commercial platinum carbon).
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
The experimental methods used in the examples of the present invention are all conventional methods unless otherwise specified.
The materials, reagents and the like used in the examples of the present invention are commercially available unless otherwise specified.
Pyridine nitrogen and Fe-N of the invention 2 The preparation principle of the co-doped carbon nanofiber is as follows: as shown in fig. 1, firstly, roughening the surface of the carbon paper, further processing the carbon paper by using ethylene as a carbon source and nitrogen as a carrier gas and utilizing a chemical vapor deposition process to obtain carbon nanofibers with controllable and uniform appearance; secondly, hydrofluoric acid is adopted to carry out chemical cutting on the carbon nano fiber, and the disordered annular structure of the outer boundary of the carbon nano fiber is corroded to form more exposed annular structuresThe boundary of the active site and the integrity of the internal carbon atom sheet layer are kept, so that an ideal carbon nano substrate is provided for subsequent doping of pyridine nitrogen; then pyridine nitrogen doping is carried out in the ammonia atmosphere, and carbon nanofibers doped with pyridine nitrogen are obtained; finally, dipping in iron salt solution and heat treatment to combine iron atoms with pyridine nitrogen atoms doped on the surface of the fiber to form Fe-N 2 Obtaining pyridine nitrogen and Fe-N 2 Co-doped carbon nanofibers. FIG. 1b is a vertical axial cross-sectional view of a single carbon nanofiber, which shows that a large number of pyridine nitrogen atoms are present at the exposed boundary of the carbon nanofiber, and Fe-N is introduced with iron atoms 2 The sites are formed at the boundary of the carbon nano-fiber, and pyridine nitrogen and Fe-N can be obtained 2 Co-doping carbon nanofibers.
Example 1
This example provides a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) and (3) placing the carbon paper in 5M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, then taking out the carbon paper, washing the carbon paper to be neutral by using deionized water, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing nickel nitrate alcohol solution with the concentration of 10wt.%, and carrying out ultrasonic treatment for 3h to ensure that the nickel nitrate is fully and uniformly dispersed in the alcohol solution. And (3) placing the dried carbon paper into nickel nitrate alcohol solution with the concentration of 10wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Putting the dried carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent airflow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and using N 2 Full (N) 2 : 3 L·min -1 99.9%) in N 2 Heating the deposition furnace to 500 ℃ under protection, and introducing H 2 And N 2 Mixed gas (N) 2 : 1 L·min -1 , 99.9%；H 2 ：1.5 L·min -1 99.9%) and incubated for 1.5 h. Then heating to 700 deg.C (N) 2 : 3 L·min -1 99.9%) followed by the introduction of N 2 And C 2 H 4 Mixed gas (N) 2 : 2.5 L·min −1 , 99.9%; C 2 H 4 : 0.8 L·min -1 ) Keeping the temperature for 30min, and finally cooling to room temperature (N) 2 : 3 L·min -1 99.9 percent) to obtain the carbon nano fiber.
(2) Dipping the carbon nano-fiber in the step (1) in 20M hydrofluoric acid solution, taking out after 0.2h, washing with deionized water to be neutral, drying, putting into a tube furnace, fixing with a self-made graphite clamp, and placing in N 2 （N 2 : 3 L·min -1 99.9%) was heated to 600 c and then NH was introduced 3 （NH 3 : 1.5 L·min -1 99.9%) and keeping the temperature for 3.5h to carry out nitrogen doping, and finally cooling to room temperature to obtain the pyridine nitrogen-doped carbon nanofiber.
(3) Preparing iron nitrate alcohol solution with the concentration of 5wt.% according to the method for preparing nickel nitrate alcohol solution in the step (1). Putting the pyridine nitrogen-doped carbon nano fiber obtained in the step (2) into a ferric nitrate alcohol solution with the concentration of 5wt.% for dipping, taking out after 1h, washing with deionized water to be neutral, putting the neutral carbon nano fiber into an oven, drying for 5h at 70 ℃, putting the neutral carbon nano fiber into a tube furnace, fixing the neutral carbon nano fiber with a self-made graphite clamp, and putting the tube furnace into a furnace for N 2 （5 L·min -1 99.9%) is heated to 600 ℃ under protection, then the temperature is kept for 2h, and finally the temperature is reduced to room temperature; immersing the obtained sample in dilute hydrochloric acid with the concentration of 3wt.% to remove residual metallic iron on the sample, then washing the sample to be neutral by deionized water, and drying the sample in an oven at 80 ℃ for 2 hours to obtain pyridine nitrogen and Fe-N 2 And co-doping the carbon nano fiber, wherein the content of pyridine nitrogen is 5.03wt%, and the content of Fe is 1.54 wt%.
Example 2
This example provides a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) and (3) placing the carbon paper in a 0.1M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. An alcohol solution of ferric nitrate was prepared at a concentration of 0.1wt.% and sonicated for 3h to ensure that the ferric nitrate was sufficiently and uniformly dispersed in the alcohol solution.And (3) placing the dried carbon paper into an iron nitrate alcohol solution with the concentration of 0.1wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Putting the dried carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent airflow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and using N 2 Full (N) 2 : 0.1 L·min -1 99.9%) in N 2 Heating the deposition furnace to 450 ℃ under protection, and introducing H 2 And N 2 Mixed gas (N) 2 : 0.1 L·min -1 , 99.9%；H 2 ：0.1 L·min -1 99.9%) and incubated for 0.1 h. Then heating to 450 ℃ (N) 2 : 0.1 L·min -1 99.9%) followed by the introduction of N 2 And C 3 H 6 Mixed gas (N) 2 : 0.1 L·min −1 , 99.9%; C 3 H 6 : 0.1 L·min -1 ) Keeping the temperature for 0.1h, and finally cooling to room temperature (N) 2 : 0.1 L·min -1 99.9 percent) to obtain the carbon nano fiber.
(2) Dipping the carbon nano fiber obtained in the step (1) in 10M hydrofluoric acid solution, taking out after 0.1h, washing with deionized water to be neutral, drying, putting into a tube furnace, fixing with a self-made graphite clamp, and placing in N 2 （N 2 : 0.1 L·min -1 99.9%) was heated to 600 c and then NH was introduced 3 （NH 3 : 0.1 L·min -1 99.9%) and keeping the temperature for 0.1h to carry out nitrogen doping, and finally cooling to room temperature to obtain the pyridine nitrogen-doped carbon nanofiber.
(3) Preparing an alcohol solution of ferric chloride with the concentration of 0.1wt.% according to the method for preparing the alcohol solution of nickel nitrate in the step (1). Putting the pyridine nitrogen-doped carbon nano fiber obtained in the step (2) into a ferric chloride alcohol solution with the concentration of 0.1wt.% for dipping, taking out after 1h, washing with deionized water to be neutral, putting the neutral carbon nano fiber into an oven, drying for 5h at 70 ℃, putting the neutral carbon nano fiber into a tube furnace, fixing the neutral carbon nano fiber with a self-made graphite clamp, and putting the tube furnace into a N-shaped furnace 2 （N 2 :0.1 L·min -1 99.9%) is heated to 400 deg.C, then is heat-insulated for 0.1h, and finally is cooled to room temperature(ii) a Immersing the obtained sample in dilute nitric acid with the concentration of 0.1wt.% to remove residual metallic iron on the sample, washing the sample to be neutral by deionized water, and drying the sample in an oven at 80 ℃ for 2 hours to obtain pyridine nitrogen and Fe-N 2 Co-doping carbon nanofibers.
Example 3
This example provides a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) and (3) placing the carbon paper in 9M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing an alcohol solution of cobalt nitrate with the concentration of 18wt.%, and carrying out ultrasonic treatment for 3 hours to ensure that the cobalt nitrate is fully and uniformly dispersed in the alcohol solution. And (3) placing the dried carbon paper into cobalt nitrate alcohol solution with the concentration of 18wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Placing the dried carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent air flow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and filling the deposition furnace with argon (Ar: 6 L.min) -1 99.9 percent), heating the deposition furnace to 650 ℃ under the protection of argon, and then introducing mixed gas of hydrogen and argon (Ar: 6 L.min) -1 , 99.9%；H 2 ：6 L·min -1 99.9%) and incubated for 4 h. Then heating to 850 deg.C (Ar: 6 L.min) -1 99.9 percent), and then introducing mixed gas of argon and ethylene (Ar: 6 L.min) −1 , 99.9%; C 2 H 4 : 4 L·min -1 ) Keeping the temperature for 4h, and finally cooling to room temperature (Ar: 6 L.min) -1 99.9 percent) to obtain the carbon nano fiber.
(2) Dipping the carbon nano-fiber in the step (1) in 22M hydrofluoric acid solution, taking out after 3h, washing with deionized water to be neutral, drying, putting into a tube furnace, fixing with a self-made graphite clamp, and placing in argon (Ar: 6 L.min) -1 99.9%) was heated to 700 deg.c and then ammonia (NH) gas was introduced 3 : 4 L·min -1 99.9%) and incubated for 8h to carry outAnd doping nitrogen, and finally cooling to room temperature to obtain the pyridine nitrogen-doped carbon nanofiber.
(3) Preparing a ferric nitrate alcohol solution with the concentration of 10wt.% according to the method for preparing the cobalt nitrate alcohol solution in the step (1). Putting the pyridine nitrogen-doped carbon nano fiber obtained in the step (2) into a ferric nitrate alcohol solution with the concentration of 10wt.% for dipping, taking out after 1h, washing with deionized water to be neutral, putting the carbon nano fiber into an oven, drying at 70 ℃ for 5h, putting the carbon nano fiber into a tubular furnace, fixing the carbon nano fiber with a self-made graphite clamp, and putting the carbon nano fiber into argon (Ar: 6 L.min) -1 99.9%) is heated to 700 ℃ firstly under the protection, then the temperature is kept for 5h, and finally the temperature is reduced to the room temperature; immersing the obtained sample in dilute nitric acid with the concentration of 10wt.% to remove residual metallic iron on the sample, then washing the sample to be neutral by deionized water, and drying the sample in an oven at 80 ℃ for 2h to obtain pyridine nitrogen and Fe-N 2 Co-doping carbon nanofibers.
Example 4
This example provides a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) and (3) placing the carbon paper in a 2M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing nickel nitrate alcohol solution with the concentration of 2wt.%, and carrying out ultrasonic treatment for 3h to ensure that the nickel nitrate is fully and uniformly dispersed in the alcohol solution. And (3) placing the dried carbon paper into nickel nitrate alcohol solution with the concentration of 2wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Putting the dried carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent airflow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and using N 2 Full (N) 2 : 1 L·min -1 99.9%) in N 2 Heating the deposition furnace to 450 ℃ under protection, and introducing H 2 And N 2 Mixed gas (N) 2 : 1 L·min -1 , 99.9%；H 2 ：1 L·min -1 99.9%) and incubated for 0.1 h. Then heating to 550 deg.C (N) 2 : 1 L·min -1 99.9%) followed by the introduction of N 2 And methane gas mixture (N) 2 : 1 L·min −1 , 99.9%; CH 4 : 1 L·min -1 ) Keeping the temperature for 1h, and finally cooling to room temperature (N) 2 : 1 L·min -1 99.9 percent) to obtain the carbon nano fiber.
(2) Putting the carbon nano-fiber obtained in the step (1) into a 15M hydrofluoric acid solution for soaking, taking out after 1 hour, washing with deionized water to be neutral, drying, putting into a tube furnace, fixing with a self-made graphite clamp, and placing in N 2 （N 2 : 1 L·min -1 99.9%) was heated to 600 c and then NH was introduced 3 （NH 3 : 1 L·min -1 99.9%) and keeping the temperature for 1h to carry out nitrogen doping, and finally cooling to room temperature to obtain the pyridine nitrogen-doped carbon nanofiber.
(3) Preparing a ferric nitrate alcohol solution with the concentration of 2wt.% according to the method for preparing the nickel nitrate alcohol solution in the step (1). Putting the pyridine nitrogen-doped carbon nano fiber obtained in the step (2) into a ferric nitrate alcohol solution with the concentration of 2wt.% for dipping, taking out after 1h, washing with deionized water to be neutral, putting the neutral carbon nano fiber into an oven, drying for 5h at 70 ℃, putting the neutral carbon nano fiber into a tube furnace, fixing the neutral carbon nano fiber with a self-made graphite clamp, and putting the tube furnace into a furnace for N 2 （N 2 :1 L·min -1 99.9%) is heated to 500 ℃ firstly under the protection, then the temperature is kept for 1h, and finally the temperature is reduced to the room temperature; immersing the obtained sample in dilute hydrochloric acid with the concentration of 1wt.% to remove residual metallic iron on the sample, washing the sample to be neutral by deionized water, and drying the sample in an oven at 80 ℃ for 2 hours to obtain pyridine nitrogen and Fe-N 2 Co-doping carbon nanofibers.
Example 5
This example provides a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) and (3) placing the carbon paper in 4M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing 5wt.% nickel nitrate alcohol solution, and carrying out ultrasonic treatment for 3 hours to ensure that the nickel nitrate is fully and uniformly dispersed in the alcohol solution. Will be provided withAnd (3) soaking the dried carbon paper in nickel nitrate alcohol solution with the concentration of 5wt.% after ultrasonic treatment for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then putting the carbon paper into an oven to be dried at 70 ℃. Placing the dried carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent air flow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and filling the deposition furnace with argon (Ar: 2 L.min) -1 99.9 percent), heating the deposition furnace to 650 ℃ under the protection of argon, and introducing mixed gas of hydrogen and argon (Ar: 2 L.min) -1 , 99.9%；H 2 ：2 L·min -1 99.9%) and incubated for 4 h. Then heating to 850 deg.C (Ar: 2 L.min) -1 99.9 percent), and then introducing mixed gas of argon and ethylene (Ar: 2 L.min) −1 , 99.9%; C 2 H 4 : 2 L·min -1 ) Keeping the temperature for 4h, and finally cooling to room temperature (Ar: 2 L.min) -1 99.9 percent) to obtain the carbon nano fiber.
(2) Dipping the carbon nano-fiber in the step (1) in 20M hydrofluoric acid solution, taking out after 2h, washing with deionized water to be neutral, drying, putting into a tube furnace, fixing with a self-made graphite clamp, and placing in argon (Ar: 2 L.min) -1 99.9%) was heated to 600 c under an atmosphere, followed by introduction of ammonia (NH) 3 : 2 L·min -1 99.9%) and keeping the temperature for 2h to carry out nitrogen doping, and finally cooling to room temperature to obtain the pyridine nitrogen-doped carbon nanofiber.
(3) Preparing a ferric nitrate alcohol solution with the concentration of 4wt.% according to the method for preparing the nickel nitrate alcohol solution in the step (1). Putting the pyridine nitrogen-doped carbon nano fiber obtained in the step (2) into a ferric nitrate alcohol solution with the concentration of 4wt.% for dipping, taking out after 1h, washing with deionized water to be neutral, putting the carbon nano fiber into an oven, drying at 70 ℃ for 5h, putting the carbon nano fiber into a tubular furnace, fixing the carbon nano fiber with a self-made graphite clamp, and putting the carbon nano fiber into argon (Ar: 2 L.min) -1 99.9%) is heated to 600 ℃ under protection, then the temperature is kept for 2h, and finally the temperature is reduced to room temperature; immersing the obtained sample in dilute hydrochloric acid with the concentration of 4wt.% to remove residual metallic iron on the sample, washing the sample to be neutral by deionized water, and drying the sample in an oven at 80 ℃ for 2 hours to obtain pyridine nitrogen and pyridine nitrogenFe-N 2 Co-doping carbon nanofibers.
Example 6
This example provides a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) and (3) placing the carbon paper in 4M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing a nickel nitrate alcohol solution with the concentration of 6wt.%, and carrying out ultrasonic treatment for 3 hours to ensure that the nickel nitrate is fully and uniformly dispersed in the alcohol solution. And (3) placing the dried carbon paper into nickel nitrate alcohol solution with the concentration of 6wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Putting the dried carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent airflow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and using N 2 Is filled with (N) 2 : 4 L·min -1 99.9%) in N 2 Heating the deposition furnace to 450 ℃ under protection, and introducing H 2 And N 2 Mixed gas (N) 2 : 4 L·min -1 , 99.9%；H 2 ：4 L·min -1 99.9%) and incubated for 3 h. Then heating to 550 deg.C (N) 2 : 4 L·min -1 99.9%) followed by the introduction of N 2 And C 2 H 4 Mixed gas (N) 2 : 4 L·min −1 , 99.9%; C 2 H 4 : 4 L·min -1 ) Keeping the temperature for 3h, and finally cooling to room temperature (N) 2 : 4 L·min -1 99.9 percent) to obtain the carbon nano fiber.
(2) Putting the carbon nano-fiber obtained in the step (1) into a 20M hydrofluoric acid solution for soaking, taking out after 2 hours, washing with deionized water to be neutral, drying, putting into a tube furnace, fixing with a self-made graphite clamp, and placing into a container with N 2 （N 2 : 4 L·min -1 99.9%) was heated to 650 deg.c, followed by introduction of NH 3 （NH 3 : 4 L·min -1 99.9%) and keeping the temperature for 4h to carry out nitrogen doping, and finally cooling to room temperature to obtain pyridine nitrogen-doped carbonAnd (3) nano fibers.
(3) Preparing a ferric nitrate alcohol solution with the concentration of 4wt.% according to the method for preparing the nickel nitrate alcohol solution in the step (1). Putting the pyridine nitrogen doped carbon nanofibers obtained in the step (2) into a ferric nitrate alcohol solution with the concentration of 4wt.% for dipping, taking out after 1 hour, washing with deionized water to be neutral, putting the neutral carbon nanofibers into an oven, drying for 5 hours at 70 ℃, putting the neutral carbon nanofibers into a tubular furnace, fixing the neutral carbon nanofibers with a self-made graphite clamp, and adding the graphite clamp into a nitrogen-doped carbon nanofiber solution 2 （N 2 :4 L·min -1 99.9%) is heated to 600 ℃ under protection, then is insulated for 3h, and finally is cooled to room temperature; immersing the obtained sample in dilute hydrochloric acid with the concentration of 6wt.% to remove residual metallic iron on the sample, washing the sample to be neutral by deionized water, and drying the sample in an oven at 80 ℃ for 2 hours to obtain pyridine nitrogen and Fe-N 2 Co-doping carbon nanofibers.
Example 7
This example provides a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber comprises the following steps:
(1) and (3) placing the carbon paper in 6M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing nickel nitrate alcohol solution with the concentration of 12wt.%, and carrying out ultrasonic treatment for 3h to ensure that the nickel nitrate is fully and uniformly dispersed in the alcohol solution. And (3) placing the dried carbon paper into nickel nitrate alcohol solution with the concentration of 12wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Placing the dried carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent air flow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and filling the deposition furnace with argon (Ar: 5 L.min) -1 99.9 percent), heating the deposition furnace to 550 ℃ under the protection of argon, and introducing mixed gas of hydrogen and argon (Ar: 5 L.min) -1 , 99.9%；H 2 ：5 L·min -1 99.9%) and incubated for 2 h. Then heating to 850 deg.C (Ar: 5 L.min) -1 99.9 percent), and then introducing a mixed gas of argon and ethylene (Ar: 5 L.min) −1 , 99.9%; C 2 H 4 : 3 L·min -1 ) Keeping the temperature for 2h, and finally cooling to room temperature (Ar: 5 L.min) -1 99.9 percent) to obtain the carbon nano fiber.
(2) Soaking the carbon nano-fiber in the step (1) in 15M hydrofluoric acid solution for 2.5h, taking out, washing with deionized water to be neutral, drying, placing into a tube furnace, fixing with a self-made graphite clamp, and placing in argon (Ar: 5 L.min) -1 99.9%) was heated to 650 deg.c under an atmosphere, followed by introduction of ammonia (NH) 3 : 5 L·min -1 99.9%) and keeping the temperature for 6h to carry out nitrogen doping, and finally cooling to room temperature to obtain the pyridine nitrogen-doped carbon nanofiber.
(3) Preparing iron nitrate alcohol solution with the concentration of 8wt.% according to the method for preparing nickel nitrate alcohol solution in the step (1). Putting the pyridine nitrogen-doped carbon nano fiber obtained in the step (2) into a ferric nitrate alcohol solution with the concentration of 8wt.% for dipping, taking out after 1h, washing with deionized water to be neutral, putting the carbon nano fiber into an oven, drying at 70 ℃ for 5h, putting the carbon nano fiber into a tubular furnace, fixing the carbon nano fiber with a self-made graphite clamp, and putting the carbon nano fiber into argon (Ar: 5 L.min) -1 99.9%) is heated to 600 ℃ under protection, then the temperature is kept for 4.5h, and finally the temperature is reduced to room temperature; immersing the obtained sample in dilute hydrochloric acid with the concentration of 9wt.% to remove residual metallic iron on the sample, then washing the sample to be neutral by deionized water, and drying the sample in an oven at 80 ℃ for 2 hours to obtain pyridine nitrogen and Fe-N 2 Co-doping carbon nanofibers.
Comparative example 1
The carbon nanofiber doped with pyridine nitrogen prepared by the comparative example comprises the following steps:
(1) and (3) placing the carbon paper in 5M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing nickel nitrate alcohol solution with the concentration of 10wt.%, and carrying out ultrasonic treatment for 3h to ensure that the nickel nitrate is fully and uniformly dispersed in the alcohol solution. And (3) placing the dried carbon paper into nickel nitrate alcohol solution with the concentration of 10wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Placing the dried carbon paperPutting the carbon paper into a chemical vapor deposition furnace and fixing the carbon paper by a self-made graphite clamp to ensure that the flow direction of subsequent air flow is vertical to the plane of the carbon paper, then vacuumizing the deposition furnace and using N 2 Full (N) 2 : 3 L·min -1 99.9%) in N 2 Heating the deposition furnace to 500 ℃ under protection, and introducing H 2 And N 2 Mixed gas (N) 2 : 1 L·min -1 , 99.9%；H 2 ：1.5 L·min -1 99.9%) and incubated for 1.5 h. Then heating to 700 deg.C (N) 2 : 3 L·min -1 99.9%) followed by the introduction of N 2 And C 2 H 4 Mixed gas (N) 2 : 2.5 L·min −1 , 99.9%; C 2 H 4 : 0.8 L·min -1 ) Keeping the temperature for 30min, and finally cooling to room temperature (N) 2 : 3 L·min -1 99.9 percent) to obtain the carbon nano fiber.
(2) Soaking the prepared carbon nano-fiber in 20M hydrofluoric acid solution for 0.2h, taking out, washing with deionized water to neutrality, drying, placing in a tube furnace, fixing with a self-made graphite clamp, and placing in N 2 （N 2 : 3 L·min -1 99.9%) was heated to 600 c and then NH was introduced 3 （NH 3 : 1.5 L·min -1 99.9%) and keeping the temperature for 3.5h to dope nitrogen, and finally cooling to room temperature to obtain the pyridine nitrogen-doped carbon nanofiber, wherein the pyridine nitrogen content is 6.24 wt%.
Comparative example 2
The Fe/N co-doped carbon nanofiber prepared by the comparative example comprises the following steps:
(1) and (3) placing the carbon paper in 5M nitric acid solution for etching for 1h, fully roughening the surface of the carbon paper, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and placing the carbon paper in an oven to be dried for 5h at 70 ℃. Preparing nickel nitrate alcohol solution with the concentration of 10wt.%, and carrying out ultrasonic treatment for 3h to ensure that the nickel nitrate is fully and uniformly dispersed in the alcohol solution. And (3) placing the dried carbon paper into nickel nitrate alcohol solution with the concentration of 10wt.% after ultrasonic treatment for soaking for 30min, taking out the carbon paper, washing the carbon paper with deionized water to be neutral, and then placing the carbon paper into an oven to be dried at 70 ℃. Putting the dried carbon paper into chemical vapor depositionFixing the furnace with a self-made graphite fixture to ensure that the flow direction of the subsequent air flow is vertical to the plane of the carbon paper, vacuumizing the deposition furnace, and using N 2 Is filled with (N) 2 : 3 L·min -1 99.9%) in N 2 Heating the deposition furnace to 500 ℃ under protection, and introducing H 2 And N 2 Mixed gas (N) 2 : 1 L·min -1 , 99.9%；H 2 ：1.5 L·min -1 99.9%) and incubated for 1.5 h. Then heating to 700 deg.C (N) 2 : 3 L·min -1 99.9%) followed by the introduction of N 2 And C 2 H 4 Mixed gas (N) 2 : 2.5 L·min −1 , 99.9%; C 2 H 4 : 0.8 L·min -1 ) Keeping the temperature for 30min, and finally cooling to room temperature (N) 2 : 3 L·min -1 99.9 percent) to obtain the carbon nano fiber.
(2) Putting the carbon nano-fiber obtained in the step (1) into a tube furnace and fixing the carbon nano-fiber by using a self-made graphite clamp in N 2 （N 2 : 3 L·min -1 99.9%) was heated to 600 c and then NH was introduced 3 （NH 3 : 1.5 L·min -1 99.9%) and keeping the temperature for 3.5h to dope nitrogen, and finally cooling to room temperature to obtain the nitrogen-doped carbon nanofiber, wherein the pyridine nitrogen content is 2.78 wt%.
(3) Preparing ferric nitrate alcohol solution according to the method for preparing nickel nitrate alcohol solution in the step (1). Putting the nitrogen-doped carbon nanofiber prepared in the step (2) into a ferric nitrate alcohol solution with the concentration of 5wt.% for dipping, taking out after 1h, washing with deionized water to be neutral, putting the neutral carbon nanofiber into an oven, drying for 5h at 70 ℃, putting the neutral carbon nanofiber into a tubular furnace, fixing the neutral carbon nanofiber with a self-made graphite clamp, and putting the neutral carbon nanofiber into a N-shaped container 2 （5 L·min -1 99.9%) is heated to 600 ℃ under protection, then the temperature is kept for 2h, and finally the temperature is reduced to room temperature; the obtained sample is immersed in dilute hydrochloric acid with the concentration of 3wt.% to remove residual metallic iron on the sample, then the sample is washed to be neutral by deionized water and is placed in an oven to be dried for 2 hours at the temperature of 80 ℃, and the Fe/N co-doped carbon nanofiber is obtained, wherein the nitrogen content is 3.03wt% and the Fe content is 1.05 wt%.
For pyridine nitrogen and Fe-N of example 1 2 Co-dopingThe hetero carbon nanofibers, the pyridine nitrogen-doped carbon nanofibers of comparative example 1, and the Fe/N co-doped carbon nanofibers of comparative example 2 were subjected to XPS spectra and i-t curve analysis, and the pyridine nitrogen and Fe-N of example 1 were observed by a scanning electron microscope 2 The co-doping of the carbon nanofibers resulted in the results shown in fig. 2 to 7.
FIG. 2 shows pyridine nitrogen and Fe-N of example 1 2 XPS spectra of co-doped carbon nanofibers, pyridine nitrogen-doped carbon nanofibers of comparative example 1, and Fe/N co-doped carbon nanofibers of comparative example 2. As can be seen from FIG. 2, at pyridine nitrogen and Fe-N 2 In the co-doped carbon nanofiber and the Fe/N co-doped carbon nanofiber, three elements of Fe, N and C exist, which indicates that the iron element and the nitrogen element in the embodiment 1 are successfully doped into the carbon nanofiber.
FIG. 3 shows pyridine nitrogen and Fe-N of example 1 2 Fe 2p XPS spectra of co-doped carbon nanofibers. As can be seen from fig. 3, the carbon nanomaterial prepared by the present invention does contain iron, and the valence states of the iron are 2 and 3.
FIG. 4 shows pyridine nitrogen and Fe-N of example 1 2 N1 s XPS comparison spectra for co-doped carbon nanofibers and pyridine nitrogen doped carbon nanofibers of comparative example 2. As can be seen from fig. 4, the valence bond configurations of the nitrogen elements doped in the carbon nanofiber of example 1 are pyridine nitrogen, that is, the invention realizes effective doping of pyridine nitrogen; the introduction of iron element shifts the peak position of pyridine nitrogen in XPS spectrum of N1 s by about 0.3eV, which shows that iron atom and nitrogen atom are combined at boundary position (Advanced Materials, 2021, 33(30), 2100171-1-9), namely the invention realizes Fe-N 2 Effective doping of (2).
FIG. 5 shows pyridine nitrogen and Fe-N of example 1 2 Scanning electron microscope images (a) of the co-doped carbon nanofibers and surface scanning distribution conditions of carbon element (b), nitrogen element (c) and iron element (d). As can be seen from FIG. 5, the elements are distributed on the surface of the carbon nanofiber uniformly without obvious agglomeration.
FIG. 6 shows pyridine nitrogen and Fe-N of example 1 2 Codoped carbon nanofibers, pyridine nitrogen-doped carbon nanofibers of comparative example 1, Fe/N-codoped carbon nanofibers of comparative example 2, and 20% Pt/C (commercial platinum/carbon)Carbon), pyridine nitrogen and Fe-N, as can be seen from fig. 6 2 The initial reduction potential and half-wave potential of the co-doped carbon nanofiber are obviously superior to those of Fe/N co-doped carbon nanofiber and pyridine nitrogen-doped carbon nanofiber, and the performance of the co-doped carbon nanofiber is almost close to 20% of Pt/C (commercial platinum carbon).
FIG. 7 shows pyridine nitrogen and Fe-N of example 1 2 I-t curves of co-doped carbon nanofibers, pyridine nitrogen-doped carbon nanofibers of comparative example 1, Fe/N co-doped carbon nanofibers of comparative example 2, and 20% Pt/C (commercial platinum carbon), as is apparent from fig. 7, pyridine nitrogen and Fe-N of the present invention 2 The codoped carbon nanofiber has oxygen reduction catalytic performance superior to that of Fe/N codoped carbon nanofiber and 20% Pt/C (commercial platinum carbon).
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.
Claims (10)
1. Pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber is characterized by comprising the following steps:
(1) preparing a substrate, etching the substrate by a strong oxidizing acid solution, then putting the substrate into an alcohol solution of transition metal salt for dipping, and then carrying out chemical vapor deposition to obtain carbon nanofibers;
(2) dipping the carbon nanofiber obtained in the step (1) by using a strong corrosive acid solution, and sequentially heating, preserving heat and cooling to obtain a pyridine nitrogen doped carbon nanofiber;
(3) dipping the pyridine nitrogen-doped carbon nanofibers obtained in the step (2) in an alcoholic solution of ferric salt, sequentially heating, preserving heat and cooling in a protective atmosphere, and then adding a dilute strong acid solution for dipping to obtain pyridine nitrogen and Fe-N 2 Co-doped carbon nanofibers.
2. The pyridine nitrogen and Fe-N of claim 1 2 Co-doping of carbon nanofibersThe preparation method is characterized by comprising the following steps: the substrate in the step (1) is a carbon material substrate; the strong oxidizing acid solution is a nitric acid solution, and the concentration of the nitric acid solution is 0.1-9M; the transition metal salt is any one of nickel nitrate, ferric nitrate and cobalt nitrate, and the concentration of the transition metal salt in the alcohol solution is 0.1-18 wt.%.
3. The pyridine nitrogen and Fe-N of claim 2 2 The preparation method of the co-doped carbon nanofiber is characterized in that the chemical vapor deposition in the step (1) is specifically performed by the following steps: and heating the substrate after the impregnation to 450-650 ℃ under a protective atmosphere, introducing hydrogen for heat preservation, continuing to heat to 450-850 ℃, introducing a carbon source gas for heat preservation, and finally cooling to room temperature.
4. Pyridine nitrogen and Fe-N according to claim 3 2 The preparation method of the co-doped carbon nanofiber is characterized by comprising the following steps: the protective atmosphere is nitrogen or argon, and the flow is 0.1-6 L.min -1 (ii) a The flow rate of the hydrogen is 0.1-6 L.min -1 (ii) a The carbon source gas is any one of propylene, ethylene and methane, and the flow rate is 0.1-4 L.min -1 。
5. The pyridine nitrogen and Fe-N of claim 4 2 The preparation method of the co-doped carbon nanofiber is characterized by comprising the following steps: the strong corrosive acid solution in the step (2) is hydrofluoric acid with the concentration of 10-22 mol.L -1 (ii) a The dipping time is 0.1-3 h; the temperature is raised to 400-700 ℃ under the protective atmosphere; and the heat preservation is carried out for 0.1-8 h under the ammonia atmosphere.
6. Pyridine nitrogen and Fe-N according to claim 5 2 The preparation method of the co-doped carbon nanofiber is characterized by comprising the following steps: the protective atmosphere is nitrogen or argon, and the flow is 0.1-6 L.min -1 (ii) a The flow of the ammonia gas is 0.1-4 L.min -1 。
7. According to claim6 a pyridine nitrogen and Fe-N 2 The preparation method of the co-doped carbon nanofiber is characterized by comprising the following steps: in the step (3), the ferric salt is ferric nitrate or ferric chloride, and the concentration of the ferric nitrate or the ferric chloride in the alcohol solution is 0.1-10 wt.%; the protective atmosphere is nitrogen or argon, and the flow is 0.1-6 L.min -1 。
8. The pyridine nitrogen and Fe-N of claim 7 2 The preparation method of the co-doped carbon nanofiber is characterized by comprising the following steps: heating to 400-700 ℃ in the step (3); the heat preservation time is 0.1-5 h; the dilute strong acid solution is dilute hydrochloric acid or dilute nitric acid, and the concentration is 0.1-10 wt.%.
9. Pyridine nitrogen and Fe-N prepared by the preparation method of any one of claims 1 to 8 2 Co-doping carbon nanofibers.
10. The pyridine nitrogen and Fe-N of claim 9 2 The co-doped carbon nanofiber is applied to the fuel cell oxygen reduction catalyst.
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| CN104289249A (en) * | 2014-11-03 | 2015-01-21 | 中国科学技术大学 | Preparation method of Fe and N-doped porous carbon nanofiber applicable to cathode catalyst for polymer fuel cell |
| CN106784872A (en) * | 2016-12-06 | 2017-05-31 | 中南大学 | A kind of method that the nitrogen-doped carbon material containing pure pyridine nitrogen is prepared based on chemical vapor deposition |
| KR20190022161A (en) * | 2017-08-25 | 2019-03-06 | 한국과학기술원 | Catalyst for oxygen reduction reaction comprising porous carbon nanofiber co-doped with transition metal and nitrogen and preparation method thereof |
| CN109888318A (en) * | 2019-02-13 | 2019-06-14 | 上海交通大学 | A kind of preparation method and application of the nitrogen co-doped C-base composte material of metal- |
| CN112864402A (en) * | 2021-01-11 | 2021-05-28 | 杭州楚佩科技有限公司 | Preparation and application of Fe-N co-doped mesoporous carbon oxygen reduction catalyst |
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| CN104289249A (en) * | 2014-11-03 | 2015-01-21 | 中国科学技术大学 | Preparation method of Fe and N-doped porous carbon nanofiber applicable to cathode catalyst for polymer fuel cell |
| CN106784872A (en) * | 2016-12-06 | 2017-05-31 | 中南大学 | A kind of method that the nitrogen-doped carbon material containing pure pyridine nitrogen is prepared based on chemical vapor deposition |
| KR20190022161A (en) * | 2017-08-25 | 2019-03-06 | 한국과학기술원 | Catalyst for oxygen reduction reaction comprising porous carbon nanofiber co-doped with transition metal and nitrogen and preparation method thereof |
| CN109888318A (en) * | 2019-02-13 | 2019-06-14 | 上海交通大学 | A kind of preparation method and application of the nitrogen co-doped C-base composte material of metal- |
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