CN114497603A - Catalyst for fuel cell, preparation method thereof and fuel cell - Google Patents

Catalyst for fuel cell, preparation method thereof and fuel cell Download PDF

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CN114497603A
CN114497603A CN202111551768.4A CN202111551768A CN114497603A CN 114497603 A CN114497603 A CN 114497603A CN 202111551768 A CN202111551768 A CN 202111551768A CN 114497603 A CN114497603 A CN 114497603A
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catalyst
fuel cell
core
metal
nanowire
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CN114497603B (en
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吕海峰
瞿威
李婷雅
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Shenzhen Academy of Aerospace Technology
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Shenzhen Academy of Aerospace Technology
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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
    • H01M4/92—Metals of platinum group
    • H01M4/923—Compounds thereof with non-metallic elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • 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
    • 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
    • H01M4/9041—Metals or alloys
    • 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
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H01M4/925—Metals of platinum group supported on carriers, e.g. powder carriers
    • H01M4/926—Metals of platinum group supported on carriers, e.g. powder carriers on carbon or graphite
    • 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 provides a catalyst for a fuel cell, a preparation method thereof and the fuel cell, wherein the preparation method of the catalyst comprises the following steps: synthesizing core metal particles; dissolving the core metal particles in a metal precursor salt mixed solution, adding a reducing agent, and carrying out a pyrolysis reduction reaction under the protection of inert gas to obtain nano particles with a nanowire core-shell structure; wherein the temperature of the pyrolysis reduction reaction is 200-230 ℃; and loading the nano particles on a carrier, and carrying out aftertreatment to obtain the catalyst for the fuel cell. The novel catalyst with the core-shell structure and the nanowire structure is prepared in one step, the process is simple, the nanowire structure directly grows on the surface of the nanoshell, the nanowire is not easy to fall off from the surface of the core-shell structure, and the stability is higher.

Description

Catalyst for fuel cell, preparation method thereof and fuel cell
Technical Field
The invention relates to the technical field of fuel cells, in particular to a catalyst for a fuel cell, a preparation method of the catalyst and the fuel cell.
Background
A fuel cell is a power generation device that directly converts chemical energy of fuel into electric energy through an electrochemical reaction without combustion, and is considered as one of the most promising power generation technologies in the 21 st century. The proton exchange membrane fuel cell has the advantages of low working temperature, quick start, high specific power, simple structure, environmental friendliness and the like, and has wide application prospect in the fields of electric automobiles, portable power supplies, fixed power stations and the like. However, the industrial development process of the pem fuel cell is limited by cost and durability, and the noble metal catalytic material used in the pem fuel cell is one of the main reasons for high cost and poor stability of the fuel cell.
At present, a Pt-based noble metal catalyst is mainly used for a proton exchange membrane fuel cell, however, the Pt catalyst has the disadvantages of high price, limited reserves, reduced stability due to the characteristic of easy corrosion in the working environment of the fuel cell, and the like, so that the industrialization process of the Pt catalyst is greatly limited. In order to solve the above problems, in recent years, means such as synthesizing Pt alloy nanoparticles having a core-shell structure are mainly used in the prior art to reduce the amount of Pt noble metal and improve the stability of the Pt catalyst, however, the method has a limited improvement on the catalytic stability of the Pt catalyst, and in the conventional catalyst, only one contact point is provided between the spherical Pt alloy nanoparticles and the surface of the carrier, so that the binding force is limited, and the stability of the catalyst is limited, and thus the method is difficult to be applied to an application scenario with high catalytic activity and stability.
Disclosure of Invention
The invention solves the problem that the existing Pt catalyst has poor catalytic activity and stability and can not meet the requirement of practical application.
In order to solve the above problems, the present invention provides a method for preparing a catalyst for a fuel cell, comprising the steps of:
synthesizing core metal particles;
dissolving the core metal particles in a metal precursor salt mixed solution, adding a reducing agent, and carrying out a pyrolysis reduction reaction under the protection of inert gas to obtain nano particles with a nanowire core-shell structure; wherein the temperature of the pyrolysis reduction reaction is 200-230 ℃;
and loading the nano particles on a carrier, and carrying out aftertreatment to obtain the catalyst for the fuel cell.
Preferably, the ratio of the volume of the reducing agent to the mass of the core metal particles is 1: 20-100.
Preferably, the step of preparing the metal precursor salt mixed solution comprises:
under the protection of inert gas, adding sodium oleate into an octadecene solution, dissolving at 180 ℃, and cooling to 60 ℃ to obtain a first solution;
and adding metal precursor salt, oleylamine and oleic acid into the first solution, and heating to 115 ℃ to obtain the metal precursor salt mixed solution.
Preferably, the reducing agent comprises iron carbonyl, cobalt carbonyl or nickel carbonyl.
Preferably, the metal precursor salt includes platinum acetylacetonate, chloroplatinic acid, chloroauric acid, gold chloride, nickel acetylacetonate, or cobalt acetylacetonate.
Preferably, the core metal particle comprises any one or more of gold, ruthenium, palladium, rhodium, iridium, nickel, cobalt, manganese, copper, tin, vanadium, gallium and molybdenum.
Preferably, the post-processing comprises: and calcining the carrier loaded with the nano particles in one or more of air, nitrogen and a hydrogen-nitrogen mixed gas, wherein the calcining temperature is 185-400 ℃, and the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 5%.
Compared with the prior art, the preparation method of the catalyst for the fuel cell has the following advantages:
firstly synthesizing core metal particles, then dissolving the core metal particles in a mixed solution of metal precursor salt, performing pyrolytic reduction reaction under the action of a reducing agent, coating a layer of metal nano film shell on the surface of the core metal nanoparticles, and simultaneously growing a metal one-dimensional nanowire on the surface of the shell, thereby obtaining the novel M/PtN catalyst with a core-shell structure and a one-dimensional nanowire structure. The core of the core-shell structure is made of non-noble metal M, the shell is made of noble metal PtN alloy, and the structure can fully expose the reaction active sites of Pt noble metal atoms, improve the dispersion degree and the utilization rate of the Pt noble metal, enable the catalyst to have more excellent electro-catalytic performance and electrochemical stability, reduce the content of the Pt noble metal in the catalyst, and save the cost and resources; the one-dimensional nanowire structure has unique anisotropy, high flexibility and high conductivity, and compared with a zero-position zero-dimensional nanoparticle structure, the one-dimensional nanowire structure has more contact points, can generate two contact points with the surface of a carrier, further forms a triangle-like structure, increases the contact and bonding force of a catalyst and the carrier, can effectively help the catalyst to be stabilized on the surface of the carrier, and further enhances the stability of the catalyst.
The preparation method organically combines the core-shell structure and the one-dimensional nanowire structure together, directly obtains the novel M/PtN catalyst with the core-shell structure and the nanowire structure in one step in single preparation, has simple and convenient process, is quick and efficient, and saves resources.
Another object of the present invention is to provide a catalyst for a fuel cell, which is prepared based on the above method for preparing a catalyst for a fuel cell.
Preferably, the catalyst for the fuel cell has a nanowire core-shell structure, the nanowire core-shell structure comprises a core-shell structure and a metal one-dimensional nanowire growing on the surface of the core-shell structure, the diameter of the PtN metal one-dimensional nanowire is 1-2nm, the length of the PtN metal one-dimensional nanowire is 1-5nm, the core-shell structure comprises core metal particles and a metal nano film coated on the surface of the core metal particles, the particle size of the inner shell metal particles is 5-7nm, and the thickness of the metal nano film is 1-3 nm.
The advantages of the catalyst for fuel cells of the present invention over the prior art are the same as the preparation method of the catalyst for fuel cells described above, and are not described herein again.
Another object of the present invention is to provide a fuel cell comprising the above catalyst for a fuel cell.
The advantages of the fuel cell of the present invention over the prior art are the same as the above-described catalyst for a fuel cell, and are not described herein again.
Drawings
FIG. 1 is a flow chart of a method for preparing a catalyst for a fuel cell in an embodiment of the present invention;
FIG. 2 is a schematic view showing the structure of a catalyst for a fuel cell in an embodiment of the invention;
FIG. 3 is an electron microscope image of core Au nanoparticles prepared according to the first embodiment of the invention;
FIG. 4 is an electron microscope image of Au/FePt nanoparticles prepared according to the first embodiment of the invention;
FIG. 5 is an electron micrograph of a core NiAu nanoparticle prepared according to example two of the present invention;
FIG. 6 is an electron microscope image of NiAu/FePt nanoparticles prepared in example II of the present invention;
FIG. 7 is a graph of the oxygen reduction activity of the NiAu/FePt/C catalyst prepared in example two of the present invention;
FIG. 8 is a graph showing the durability test of the NiAu/FePt/C catalyst prepared in example II of the present invention;
FIG. 9 is an electron microscope scan of NiAu/CoPt nanoparticles prepared in example III of the present invention;
FIG. 10 is an electron microscope scanning image of Ni nanoparticles prepared in example four of the present invention.
Description of reference numerals:
1-core metal particles; 2-metal nano-film; 3-metal one-dimensional nanowires.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
It is noted that the description of the term "some specific embodiments" in the description of the embodiments herein is intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. Throughout this specification, the schematic representations of the terms used above do not necessarily refer to the same implementation or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Referring to fig. 1, a method for preparing a catalyst for a fuel cell according to an embodiment of the present invention includes the steps of:
synthesizing core metal particles;
dissolving the core metal particles in a metal precursor salt mixed solution, adding a reducing agent, and carrying out a pyrolysis reduction reaction under the protection of inert gas to obtain nano particles with a nanowire core-shell structure; wherein the temperature of the pyrolysis reduction reaction is 200-230 ℃;
and loading the nano particles on a carrier, and carrying out aftertreatment to obtain the catalyst for the fuel cell.
In this embodiment, core metal particles are first synthesized, and then dissolved in a mixed solution of metal precursor salts, a pyrolytic reduction reaction occurs under the action of a reducing agent and at a temperature of 200-. And loading the nano particles with the nano wire core-shell structure on a carrier, and carrying out post-treatment to obtain the catalyst for the fuel cell.
The core of the core-shell structure is made of non-noble metal M, the shell is made of noble metal PtN alloy, and the structure can fully expose the reaction active sites of Pt noble metal atoms, improve the dispersion degree and the utilization rate of the Pt noble metal, enable the catalyst to have more excellent electro-catalytic performance and electrochemical stability, reduce the content of the Pt noble metal in the catalyst, and save the cost and resources;
the catalyst prepared by the embodiment has a core-shell structure and a nanowire structure, the performance of the catalyst is effectively improved, and compared with a mode of firstly synthesizing the core-shell structure, then synthesizing the nanowire and finally physically combining, the catalyst with the nanowire core-shell structure is prepared by one step through the method, the synthesis method of the embodiment is simple, the catalyst is prepared by one step and is suitable for mass production, the nanowire structure directly grows on the surface of the nanoshell, the nanowire is not easy to fall off from the surface of the core-shell structure, and the stability is stronger.
In addition, compared with a zero-position zero-dimensional nanoparticle structure, the novel catalyst structure prepared by the embodiment has more contact points due to the unique anisotropy, high flexibility and high conductivity of the one-dimensional nanowire structure, and can generate two contact points with the surface of a carrier to form a triangle-like structure, so that the contact and bonding force between the catalyst and the carrier are increased, the catalyst can be effectively helped to be stabilized on the surface of the carrier, and the stability of the catalyst is further enhanced.
In the embodiment, the core-shell structure and the one-dimensional nanowire structure are organically combined together, the novel M/PtN catalyst with the core-shell structure and the nanowire structure is directly obtained in one time in single preparation, the process is simple, convenient, fast and efficient, and the resources are saved.
In some embodiments, the ratio of the volume of the reducing agent to the mass of the core metal particles is 1:20 to 100, thereby allowing easier nanowire formation on the shell surface while forming the nanoshell structure through control of the amount of reducing agent used and temperature control of the pyrolytic reduction reaction.
In some embodiments, the step of preparing the metal precursor salt mixed solution comprises:
under the protection of inert gas, adding sodium oleate into an octadecene solution, dissolving at 180 ℃, and cooling to 60 ℃ to obtain a first solution;
and adding metal precursor salt, oleylamine and oleic acid into the first solution, and heating to 115 ℃ to obtain the metal precursor salt mixed solution.
The metal precursor salt comprises platinum acetylacetonate, chloroplatinic acid, chloroauric acid, gold chloride, nickel acetylacetonate or cobalt acetylacetonate and provides an effective catalytic active component for the catalyst, and the catalyst obtained by adopting a platinum acetylacetonate system has higher consistency, higher stability and higher catalytic activity than an M/PtN catalyst prepared by adopting a chloroplatinic acid system, so that the platinum acetylacetonate system is used in the preferred embodiment.
In some embodiments, after dissolving the inner core metal particles in the metal precursor salt mixed solution, adding a reducing agent under a protective atmosphere, raising the temperature to 200-230 ℃, performing a pyrolytic reduction reaction, and after reacting for 0.5h, cooling the solution to room temperature. Wherein the reducing agent comprises carbonyl iron, carbonyl cobalt or carbonyl nickel.
Preferably, the whole pyrolytic reduction reaction is divided into a plurality of stages and is carried out in different temperature intervals respectively, wherein the temperature in the temperature intervals is increased in a gradient manner from low to high, and the mixture solvent is dynamically heated from a low temperature interval to a high temperature interval to carry out the pyrolytic reduction reaction. Therefore, the generated metal particles are uniformly dispersed and loaded on the carrier, and the particle size of the metal particles is uniform, so that the nanowire core-shell structure M/PtN catalyst with high activity and durability is synthesized.
In some embodiments, the product of the pyrolytic reduction reaction is added to 40mL of isopropanol and then centrifuged at 8500 rpm for 8min in a centrifuge to separate the product from the solution. The centrifuged product was redispersed in 30mL of hexane and 30mL of ethanol solution and centrifuged twice, and finally the obtained product was redissolved in hexane solution for use.
In some specific embodiments, the support comprises a carbon support. Illustratively, the carbon support specifically includes: carbon black, carbon nanotubes, graphitic carbon, or graphene.
The carbon material is widely applied to the preparation of the catalyst as a carrier, compared with the catalyst loaded by oxide, the carbon carrier catalyst has high activity, uniform distribution and low cost, and can recycle precious metals from waste catalysts through the combustion of the carbon carrier, thereby improving the resource utilization rate. Meanwhile, the carbon carrier catalyst has unique properties of a developed microporous structure, electron conductivity, weak acidity of the surface and the like, and is favorable for improving the electrochemical catalytic activity and stability of the catalyst.
Specifically, the prepared nano-wire core-shell structure M/PtN catalyst nano-particles are dissolved in a corresponding solvent, and carbon powder is added for mechanical stirring and ultrasonic treatment to prepare the carbon-supported catalyst. Wherein the particle size range of the carbon support is preferably 40-200nm, and the specific surface area range is preferably 100-600m2(ii) in terms of/g. Thereby, a catalyst having more excellent electrochemical catalytic activity and stability is obtained.
In some specific embodiments, the performing post-processing specifically includes: acid washing, drying and reduction treatment under air, nitrogen or hydrogen-nitrogen mixed gas.
Specifically, the initial catalyst obtained through the above steps has various impurities such as an active agent, a solvent, moisture, an intermediate, and an organic substance remaining on the surface thereof, which affect the performance of the catalyst, and the initial catalyst is subjected to a purification treatment for removing impurities, and an acid washing treatment for removing impurities such as a surfactant is preferably performed using acetic acid or perchloric acid. The drying aims at removing moisture on the surface of the catalyst by high-temperature evaporation and removing the surfactant of the catalyst by high-temperature calcination in air. The reduction treatment is carried out under the mixed gas of hydrogen and nitrogen, so that the surface structure reconstruction of the catalyst is realized, the catalyst is stabilized, and the catalytic activity of the catalyst is improved.
In some specific embodiments, the mixed hydrogen-nitrogen gas is a mixed hydrogen-nitrogen gas with a hydrogen volume fraction of 5%, and the temperature of the mixed hydrogen-nitrogen gas is between 185 ℃ and 400 ℃.
In particular, H2Has high reducibility, and can perform reduction reaction with oxide and organic matters on the surface of the catalyst to remove organic impurities, while H2At the same time, the catalyst has higher activity, so that the reduction reaction is possibly too violent to burn the catalyst, and H needs to be added2The proportion of the mixed gas is controlled within a certain range, in this embodiment, H is set2The proportion of the mixed gas is controlled to be 5 percentThe temperature is controlled at 185-400 ℃, and H can be prevented on the premise of ensuring that the impurities such as oxide, organic matters and the like on the surface of the catalyst are removed quickly and efficiently2Too high a content leads to catalyst burnout.
In some specific embodiments, the M metal comprises any one or more of gold (Au), ruthenium (Ru), palladium (Pd), rhodium (Rh), iridium (Ir), nickel (Ni), cobalt (Co), manganese (Mn), copper (Cu), tin (Sn), vanadium (V), gallium (Ga), or molybdenum (Mo). Therefore, the metal core with excellent performance is provided for the catalyst, the metal material is easy to obtain, the electro-catalytic performance of the catalyst is guaranteed, meanwhile, the content of the Pt noble metal in the catalyst is effectively reduced, the cost is low, the environment is protected, and the cost and the resources are saved.
In some embodiments, the PtN metal is any one of PtFe, PtCo, or PtNi. Therefore, a metal shell with excellent performance is provided for the catalyst, cheap metals such as Fe, Co and Ni are mixed into the Pt noble metal, so that the reaction active sites of the Pt noble metal atoms are fully exposed, the dispersity and the utilization rate of the Pt noble metal are improved, the catalyst has more excellent electro-catalytic performance and electrochemical stability, the metals such as Fe, Co and Ni are easy to obtain and excellent in performance, the content of the Pt noble metal in the catalyst is effectively reduced while the performance of the catalyst is ensured, the cost is low, the environment is protected, and the cost and the resources are saved.
Another embodiment of the present invention provides a catalyst for a fuel cell, which is prepared based on the above preparation method of the catalyst for a fuel cell.
In some specific embodiments, the catalyst for a fuel cell has an M/PtN nanowire core-shell structure, as shown in fig. 2, a particle size range of a core metal particle 1 is 5-7nm, a PtN metal nano-film 2 is an outer shell, a PtN metal one-dimensional nanowire 3 is grown on a surface of the PtN metal nano-film 2, a thickness of the PtN metal nano-film 2 is 1-3nm, a diameter of the PtN metal one-dimensional nanowire 3 is 1-2nm, and a length of the PtN metal one-dimensional nanowire 3 is 1-5 nm.
Specifically, the particle size of the core of the prepared catalyst is controlled within the range of 5-7nm, the thickness of the PtN metal nano film shell is controlled within the range of 1-3nm, and the diameter of the PtN metal one-dimensional nanowire is controlled within the range of 1-2nm, so that the nanowire core-shell structure nano particle catalyst has a proper size, the proportion distribution of the core, the PtN metal nano film shell and the PtN metal one-dimensional nanowire is proper, and the catalyst with better electrochemical catalytic activity and stability is obtained.
Another embodiment of the present invention also provides a fuel cell including the catalyst for a fuel cell described above.
The fuel cell of this example includes the fuel cell catalyst described above, and therefore the fuel cell of this example has a high power density and significantly improved electrochemical performance.
The technical scheme of the invention is further described below by combining specific embodiments, and the purpose and advantages of the invention are clear.
The first embodiment is as follows:
step S1: synthesizing Au nano particles to obtain a catalyst inner core; the method specifically comprises the following steps:
step S11: 0.2g of chloroauric acid (HAuCl)4) Dissolving in 10ml mixed solution of tetralin and Oleylamine (OAM), and magnetically stirring in ice water bath at 4 deg.C to obtain HAuCl4And (3) solution.
Step S12: 0.5mmol of tetrabutylammonium bromide (TBAB) was dissolved in a mixed solution of 1ml of tetralin and 1ml of oleylamine under ultrasonic conditions to obtain a TBAB solution, and the TBAB solution was injected into HAuCl obtained in step S114In the solution, centrifuging to obtain Au seeds with the particle size of 3 nm;
step S13: 30mg of the Au seed having a particle size of 3nm obtained in step S12 was added to a mixed solution of 10ml of Octadecene (ODE), 10ml of oleylamine and 0.2g of chloroauric acid, and N was introduced at room temperature2Stirring, slowly heating to 80 ℃, stirring for 2h, and centrifuging to obtain Au nanoparticles with the particle size of 7 nm.
Step S2: the preparation method of the Au/FePt nano-particles with the nanowire core-shell structure by adopting a one-step synthesis method comprises the following steps:
step S21: dissolving 100mg of sodium oleate in 12mL of ODE solution under the protection of nitrogen, stirring and heating to 180 ℃, then reducing the temperature to 60 ℃, adding 0.25mmol of Pt (acac)2, 3mL of OAM and 1mL of OA (Oleic acid ) into the solution, and increasing the temperature to 115 ℃ to obtain a second mixed solution;
step S22: dissolving 30mg of Au nanoparticles obtained in step S13 in the second mixed solution, and dissolving in N2Under protection, 0.5mL of Fe (CO) is injected5Heating the solution to 225 ℃, keeping the temperature for 0.5h, and cooling to room temperature to obtain a third mixed solution;
step S23: adding 40mL of isopropanol into the third mixed solution, centrifuging for 8min at 8500 revolutions by using a centrifuge, re-dispersing the centrifuged product into 30mL of hexane and 30mL of ethanol solution, and centrifuging twice to obtain Au/FePt nanoparticles with nanowire core-shell structures;
step S3: loading the nanowire core-shell structure Au/FePt nanoparticles on a carrier, and performing post-treatment to obtain an Au/FePt/C catalyst, which specifically comprises the following steps:
step S31: dissolving the Au/FePt nano-particles prepared in the step S23 in n-hexane, adding carbon powder, performing mechanical stirring and ultrasonic treatment, and depositing the Au/FePt nano-particles on a carbon supporter to obtain an initial Au/FePt/C catalyst, wherein the volume ratio of the carbon powder to the Au/FePt nano-particles is 2: 1;
step S32: the initial Au/FePt catalyst obtained in step S31 was stirred in acetic acid for 1 hour and dried in a vacuum oven at 70 deg.C in H2/Annealing in Ar mixed gas at 300 deg.C for 1H, centrifuging twice in ethanol, and centrifuging once in deionized water to obtain Au/FePt/C catalyst, wherein H2/H in Ar mixed gas2Is 5% by volume.
Electron microscope tests are respectively performed on the Au nanoparticles prepared in step S1 and the Au/FePt nanoparticles prepared in step S2, and the results are shown in fig. 3 and 4, where fig. 3 is an electron microscope image of the Au nanoparticles as a core, fig. 4 is an electron microscope image of the Au/FePt nanoparticles, and it can be seen from a comparison between fig. 3 and 4 that a one-dimensional nanowire grows on the surface of the nanoshell while the surface of the Au nanoparticles is coated with the nanoshell.
Example two:
this example differs from example one in that NiAu alloy nanoparticles were used instead of Au nanoparticles as the catalyst core.
Step S1: synthesizing NiAu nano particles to obtain a catalyst inner core;
step S11: under the protection of nitrogen and magnetic stirring, 0.2mmol of HAuCl4·3H2Mixing and stirring O (chloroauric acid trihydrate), 9mL of OAM and 0.32mL of OA, carrying out ultrasonic treatment, heating to 60 ℃, and keeping the temperature for 20min to obtain a first mixed solution;
step S12: 0.25mmol of Ni (acac)2Dissolving (nickel acetylacetonate) in 3mL of OAM to obtain a second mixed solution;
step S13: and when the first mixed solution is in a clear state, adding the second mixed solution into the first mixed solution, stirring, slowly raising the temperature to 220 ℃ at the speed of 4-5 ℃/min, preserving the temperature for 30min, cooling the solution to room temperature, centrifuging to obtain initial NiAu nanoparticles, re-dispersing the initial NiAu nanoparticles in 30mL of hexane and 30mL of ethanol solution, and centrifuging twice to obtain NiAu nanoparticles serving as a catalyst core.
Step S2: mixing Pt (acac)2, sodium oleate, ODE, OAM and OA solution to obtain mixed solution, dissolving the catalyst kernel in the mixed solution, adding reducing agent Fe (CO)5(pentahydroxyl iron) and reacting to obtain NiAu/FePt nano particles with nanowire core-shell structures;
step S3: and loading the NiAu/FePt nano particles with the nanowire core-shell structure on a carrier, and performing post-treatment to obtain the NiAu/FePt/C catalyst.
The specific steps of step S2 and step S3 are the same as those in the first embodiment, and are not repeated herein.
Electron microscope tests are respectively performed on the NiAu nanoparticles prepared in step S1 and the NiAu/FePt nanoparticles prepared in step S2, and the results are shown in fig. 5 and 6, where fig. 5 is an electron microscope image of the NiAu nanoparticles as the core, fig. 6 is an electron microscope image of the NiAu/FePt nanoparticles, and a comparison of fig. 5 and 6 shows that a one-dimensional nanowire is grown on the surface of the nano shell while the surface of the NiAu nanoparticles is coated with the nano shell.
The NiAu/FePt/C catalyst prepared in this example was tested for catalytic performance.
First, a working electrode was prepared using a NiAu/FePt/C catalyst. The method specifically comprises the following steps: the NiAu/FePt/C/C catalyst prepared in the embodiment is subjected to ultrasonic dispersion in deionized water, isopropanol or naphthol solution to obtain 2mgmL-1The catalyst slurry of (4); and (3) dropping 20 mu L of the slurry on a glassy carbon electrode with the diameter of 5mm, and drying at room temperature to obtain the NiAu/FePt/C electrode.
The following tests were then performed, test one: placing the NiAu/FePt/C electrode at 0.5MH2SO4In the solution, chemical transient CV technology is adopted for scanning, the CV scanning range is 0-1.2V, and the scanning speed is 50mVs-1；
And (2) testing: and (3) carrying out ORR performance test on the NiAu/FePt/C electrode under a rotating disk electrode, and introducing high-purity oxygen into the electrolyte for 30 minutes to enable the oxygen in the electrolyte to reach a saturated state. The scanning range is 1.0-0.2V, the scanning speed is 10mVs-1, and the rotating speed is 1600 revolutions.
For convenience of description, the electrode to which the conventional Pt/C catalyst was applied was referred to as a comparative example electrode, and the electrode to which the catalyst of example two of the present invention was applied was referred to as a NiAu/FePt/C electrode, and the above-described tests were performed on the NiAu/FePt/C electrode and the comparative example electrode, respectively, and the results are shown in FIGS. 7 and 8.
Wherein, fig. 7 is a graph comparing the oxygen reduction activity of the NiAu/FePt/C catalyst provided in this example with that of the comparative catalyst, wherein the ordinate Current density I represents the Current density in milliamperes (mA), and the abscissa Potential represents the Potential in (V), and it can be seen from fig. 7 that the oxygen reduction performance of the catalyst of this example is better than that of the comparative catalyst, and the Potential ratio of the catalyst of this example is 40mV higher than that of the comparative catalyst at the same Current density.
Fig. 8 is a graph of durability of the NiAu/FePt/C catalyst provided in the embodiment of the present invention, in a coordinate system, a Current density I in milliamperes (mA) is represented by an ordinate, and a Potential in volts is represented by an abscissa, and as can be seen from fig. 8, a curve of the Potential and the Current density almost coincides with an initial curve after the catalyst of the embodiment cycles for 5000 times, which illustrates that the durability of the NiAu/FePt/C catalyst of the embodiment is superior.
Example three:
the difference between the present embodiment and the second embodiment is that the reducing agent is Co (CO)5(pentahydroxycobalt).
Step S1: synthesizing NiAu nano particles to obtain a catalyst inner core;
step S2: mixing Pt (acac)2, sodium oleate, ODE, OAM and OA solution to obtain mixed solution, dissolving the catalyst kernel in the mixed solution, adding reducing agent Co (CO)5(pentahydroxyl cobalt) and reacting to obtain NiAu/CoPt nano particles with nanowire core-shell structures;
step S21: dissolving 100mg of sodium oleate in 12mL of ODE solution under the protection of nitrogen, stirring and heating to 180 ℃, then reducing the temperature to 60 ℃, adding 0.25mmol of Pt (acac)2, 3mL of OAM and 1mL of OA (Oleic acid ) into the solution, and increasing the temperature to 115 ℃ to obtain a second mixed solution;
step S22: 30mg of the second Au nanoparticles obtained in the step S13 were dissolved in the second mixed solution, and the solution was stirred in a stirrer2Under protection, 0.5mL of Co (CO) is injected5Heating the (pentahydroxycobalt) solution to 225 ℃, keeping the temperature for 0.5h, and cooling to room temperature to obtain a third mixed solution;
step S23: adding 40mL of isopropanol into the third mixed solution, centrifuging for 8min at 8500 revolutions by using a centrifuge, re-dispersing the centrifuged product into 30mL of hexane and 30mL of ethanol solution, and centrifuging twice to obtain the NiAu/CoPt nano-particles with the nanowire core-shell structure;
step S3: and loading the NiAu/CoPt nano particles with the nanowire core-shell structure on a carrier, and performing post-treatment to obtain the NiAu/CoPt catalyst.
The steps S1 and S3 are the same as those in the embodiment, and are not repeated herein.
The NiAu/CoPt nanoparticles prepared in step S2 were subjected to electron microscope scanning, and the result is shown in fig. 9, and it can be seen from fig. 9 that the PtCo one-dimensional nanowires were grown on the surface of the nanoshell while the nanoshell was coated on the surface of the NiAu nanoparticles.
Example four:
this example differs from example one in that Ni nanoparticles are used instead of Au nanoparticles as the catalyst core.
Step S1: synthesizing Ni nano particles to obtain a catalyst kernel;
step S11: 257mg of Ni (acac) are added under nitrogen protection and magnetic stirring215mL of OAM and 0.32mL of OA were mixed and stirred, slowly heated for 20min to 110 ℃ and incubated for one hour. Obtaining a light green first mixed solution;
step S12: dissolving OAM in BTB (bromothymol blue) solution to obtain a second mixed solution, and cooling the second mixed solution to 90 ℃;
step S13: and quickly injecting the first mixed solution into 264mg of the second mixed solution, and centrifuging to obtain Ni nano-particles serving as catalyst cores.
Step S2: mixing Pt (acac)2, sodium oleate, ODE, OAM and OA solution to obtain mixed solution, dissolving the catalyst kernel in the mixed solution, adding reducing agent Fe (CO)5(pentahydroxyiron) and reacting to obtain the nanowire core-shell structure Ni/FePt nanoparticles;
step S3: and loading the nanowire core-shell structure Ni/FePt nanoparticles on a carrier, and performing post-treatment to obtain the Ni/FePt catalyst.
The specific steps of step S2 and step S3 are the same as those in the first embodiment, and are not described herein again.
The Ni nanoparticles obtained in step S1 were subjected to electron microscope scanning, and the results are shown in fig. 10.
EXAMPLE five
This example differs from example one in that 10mg of Au nanoparticles were dissolved in the second mixed solution in step S22, followed by N2Under the protection ofInjecting 0.5mL of Fe (CO)5And (five-hydroxyl iron) solution, raising the reaction temperature to 230 ℃, preserving the temperature for 0.5h, and cooling to room temperature to obtain a third mixed solution.
EXAMPLE six
This example differs from example one in that 50mg of Au nanoparticles were dissolved in the second mixed solution in step S22, followed by N2Under protection, 0.5mL of Fe (CO) is injected5Heating the reaction temperature to 200 ℃, preserving the temperature for 0.5h, and cooling to room temperature to obtain a third mixed solution.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.

Claims (10)

1. A method for producing a catalyst for a fuel cell, comprising:
synthesizing core metal particles;
dissolving the core metal particles in a metal precursor salt mixed solution, adding a reducing agent, and carrying out a pyrolysis reduction reaction under the protection of inert gas to obtain nano particles with a nanowire core-shell structure; wherein the temperature of the pyrolysis reduction reaction is 200-230 ℃;
and loading the nano particles on a carrier, and carrying out aftertreatment to obtain the catalyst for the fuel cell.
2. The method of producing a fuel cell catalyst according to claim 1, characterized in that a ratio of a volume of the reducing agent to a mass of the core metal particles is 1: 20-100.
3. The method of preparing a catalyst for a fuel cell according to claim 1, wherein the step of preparing the metal precursor salt mixed solution includes:
under the protection of inert gas, adding sodium oleate into an octadecene solution, dissolving at 180 ℃, and cooling to 60 ℃ to obtain a first solution;
and adding metal precursor salt, oleylamine and oleic acid into the first solution, and heating to 115 ℃ to obtain the metal precursor salt mixed solution.
4. The method of producing a catalyst for a fuel cell according to claim 1, wherein the reducing agent includes iron carbonyl, cobalt carbonyl, or nickel carbonyl.
5. The method of preparing a catalyst for a fuel cell according to claim 1, wherein the metal precursor salt includes platinum acetylacetonate, chloroplatinic acid, chloroauric acid, gold chloride, nickel acetylacetonate, or cobalt acetylacetonate.
6. The method of manufacturing a catalyst for a fuel cell according to claim 1, wherein the core metal particles include any one or more of gold, ruthenium, palladium, rhodium, iridium, nickel, cobalt, manganese, copper, tin, vanadium, gallium, and molybdenum.
7. The method of producing a catalyst for a fuel cell according to claim 1, characterized in that the post-treatment comprises: and calcining the carrier loaded with the nano particles in one or more of air, nitrogen and a hydrogen-nitrogen mixed gas, wherein the calcining temperature is 185-400 ℃, and the volume fraction of hydrogen in the hydrogen-nitrogen mixed gas is 5%.
8. A catalyst for fuel cells, characterized by being produced based on the production method for a catalyst for fuel cells according to any one of claims 1 to 8.
9. The catalyst for the fuel cell according to claim 8, wherein the catalyst for the fuel cell has a nanowire core-shell structure, the nanowire core-shell structure comprises a core-shell structure and a metal one-dimensional nanowire (3) growing on the surface of the core-shell structure, the metal one-dimensional nanowire (3) has a diameter of 1-2nm and a length of 1-5nm, the core-shell structure comprises a core metal particle (1) and a metal nano-film (2) coated on the surface of the core metal particle (1), the particle size of the inner shell metal particle (1) is 5-7nm, and the thickness of the metal nano-film (2) is 1-3 nm.
10. A fuel cell characterized by comprising the catalyst for a fuel cell according to claim 8 or 9.
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