CN119187583B

CN119187583B - A platinum-based nanowire electrocatalytic material and its self-assembly preparation method and application

Info

Publication number: CN119187583B
Application number: CN202411306173.6A
Authority: CN
Inventors: 邬剑波; 马艳玲; 宋安然; 李燕洁; 彭佳恒; 胡昊
Original assignee: Shanghai Jiao Tong University
Current assignee: Shanghai Jiao Tong University
Priority date: 2024-09-19
Filing date: 2024-09-19
Publication date: 2025-11-04
Anticipated expiration: 2044-09-19
Also published as: CN119187583A

Abstract

The invention belongs to the technical field of oxygen reduction catalytic materials, and relates to a self-assembly preparation method of a platinum-based nanowire electrocatalytic material and application thereof in oxygen reduction reaction, wherein the preparation method comprises the steps of mixing platinum precursor salt and transition metal precursor salt, heating and reducing in reducing gas, and then heating and self-assembling in diluting reducing gas to obtain the platinum-based nanowire electrocatalytic material; in the heating reduction, the reduction temperature is 100-200 ℃, and in the heating self-assembly, the heating temperature is 250-300 ℃. Compared with the prior art, the preparation process is simple, and the growth of the multi-element metal nanowire can be controlled without a complex organic end capping reagent. Under the auxiliary action of reducing gas, the metal nanowire grows in a self-assembled mode through different adsorption energy of different crystal faces on the gas, can be used for oxygen reduction reaction, and has excellent catalytic performance.

Description

Platinum-based nanowire electrocatalytic material and self-assembly preparation method and application thereof

Technical Field

The invention belongs to the technical field of oxygen reduction catalytic materials, and relates to a platinum-based nanowire electrocatalytic material, a self-assembly preparation method thereof and application thereof in oxygen reduction reaction.

Background

The metal nanowire has excellent characteristics of high conductivity, unique optical characteristics, high length-diameter ratio and the like. Compared with nano particles, the one-dimensional platinum-based nanowire material has a larger length-diameter ratio, is favorable for constructing a self-supporting 3D network structure, provides a continuous electron transmission path, reduces charge transfer resistance, improves the conductivity and dynamics of an electrode, and shows excellent performance in the aspect of electrocatalysis.

In order to realize the preparation of the nanowire, patent CN111313045 discloses a platinum-copper alloy nanowire, a preparation method and application thereof, and the platinum-copper alloy nanowire has strong catalytic activity and good stability when being used as an anode catalyst of a methanol fuel cell, but the catalyst is prepared by a hydrothermal method, so that the large-scale industrialization is difficult to realize. And the patent does not mention a method for preparing other transition metal and platinum synthesized platinum-based nanowire catalysts, and has no universality. Patent CN105081341a provides a liquid phase synthesis method for obtaining platinum nanowire network, although the preparation method is simple to operate and has high reaction speed, the method needs to use organic surfactant during synthesis, which is unfavorable for catalytic activity and needs further treatment to remove the active agent. At present, the one-dimensional platinum-based nanowire is mainly prepared by liquid phase, an active agent is introduced in the preparation process, and large-scale industrialization is difficult to realize.

Therefore, there is an urgent need to develop a large-scale platinum-based nanowire catalyst with clean surface and high universality, which is applied as a cathode catalyst of a fuel cell.

Disclosure of Invention

The invention aims to provide a platinum-based nanowire electrocatalytic material, a self-assembly preparation method thereof and application thereof in oxygen reduction reaction. The preparation process is simple, and the growth of the multi-element metal nanowire can be controlled without a complex organic end capping reagent. Under the auxiliary action of reducing gas, the metal nanowire grows in a self-assembled mode through different adsorption energy of different crystal faces on the gas, can be used for oxygen reduction reaction, and has excellent catalytic performance.

The aim of the invention can be achieved by the following technical scheme:

The first aspect of the invention provides a self-assembly preparation method of a platinum-based nanowire electrocatalytic material, comprising:

mixing platinum precursor salt and transition metal precursor salt, heating and reducing in reducing gas, and then heating and self-assembling in diluted reducing gas to obtain a platinum-based nanowire electrocatalytic material;

In the heating reduction, the reduction temperature is 100-200 ℃, and in the heating self-assembly, the heating temperature is 250-300 ℃.

Further, the reducing gas is hydrogen.

Further, the dilution reducing gas is a mixture of hydrogen and an inert gas.

Further, the content of the hydrogen is 5-10vol%.

Further, in the transition metal precursor salt, the transition metal is selected from at least one of iron, nickel, copper or cobalt.

Further, in the platinum precursor salt and the transition metal precursor salt, the molar ratio of platinum to transition metal is (1-3): 1.

Further, the platinum precursor salt is chloroplatinic acid salt, and the transition metal precursor salt is selected from acetylacetonate.

Further, the mixing process of the platinum precursor salt and the transition metal precursor salt further comprises mixing the platinum precursor salt and the transition metal precursor salt together with a carrier.

Further, the carrier is selected from porous carbon powder or titanium dioxide nano particles, and the dosage is 80-120 mg/0.1mmol Pt.

In a second aspect, the invention provides a platinum-based nanowire electrocatalytic material prepared by a method as described above.

A third aspect of the present invention provides the use of a platinum-based nanowire electrocatalyst material comprising using the platinum-based nanowire electrocatalyst material as an electrode material for the preparation of a fuel cell.

The invention utilizes the self-assembly characteristic of metal in hydrogen environment, realizes the purpose of synthesizing the pure platinum/binary platinum-based alloy nanowire metal material with controllable morphology through simple reduction reaction, simultaneously avoids the influence of an organic end capping agent on the catalytic performance of the metal nanowire material, and realizes the purpose of preparing the nanowire metal material with clean surface. The method has universality, can be used for synthesizing nanowires of different platinum-based metals, and the prepared platinum-based alloy nanowire material has excellent electrocatalytic oxygen reduction performance due to low noble metal content and exposure of high-index crystal faces. And the method is more suitable for mass industrial production compared with the traditional liquid phase synthesis.

Compared with the prior art, the invention has the following characteristics:

1) The self-assembled metal nanowire prepared by the invention has the advantages that the catalyst has high electrocatalytic oxygen reduction activity due to the synergistic effect that the noble metal platinum of the self-assembled metal nanowire is not higher than the transition metal, and the catalyst cost is greatly reduced;

2) The invention adopts gas phase reaction, is different from the traditional wet chemical method, has simple preparation process and is suitable for large-scale batch production;

3) According to the preparation method, any end capping agent is not required to be introduced in the preparation process, the surface of the catalyst product is clean, special treatment is not required, the metal exposure area is large, excellent catalytic activity is shown, the method is environment-friendly, and the production cost is reduced;

4) The invention has high universality, and is not only suitable for the preparation of self-assembled nanowires of pure platinum metal, but also suitable for the self-assembled synthesis of alloy nanowires with different transition metal components and proportions.

Drawings

FIG. 1 is a process flow diagram of a method for self-assembling preparation of a platinum-based nanowire electrocatalytic material according to the present invention;

FIG. 2 is a transmission electron micrograph of a platinum-based nanowire electrocatalytic material prepared according to the present invention, (1) one-dimensional platinum nickel alloy nanowires (Pt ₃ Ni NWs) prepared in example 1, (2) one-dimensional platinum copper alloy nanowires (PtCu NWs) prepared in example 2, (3) one-dimensional platinum cobalt alloy nanowires (PtCo NWs) prepared in example 3, and (4) one-dimensional platinum iron alloy nanowires (PtFe NWs) prepared in example 6;

FIG. 3 is a transmission electron micrograph of a one-dimensional platinum-cobalt alloy nanowire prepared according to the present invention (1) Pt: co=1:1, example 3, (2) Pt: co=2:1, example 4, (3) Pt: co=3:1, example 5; the particle size distribution of the one-dimensional platinum-cobalt alloy nanowire prepared according to the present invention (4) Pt: co=1:1, example 3, (5) Pt: co=2:1, example 4, (6) Pt: co=3:1, example 5;

FIG. 4 shows XRD and EDS element distributions of one-dimensional platinum-cobalt alloy nanowires prepared in examples 3-5;

FIG. 5 is a transmission electron micrograph of a porous carbon-supported one-dimensional platinum-based nanowire prepared according to the present invention (1) PtCo nanowires, example 7, (2) PtFe nanowires, example 8;

FIG. 6 is an oxygen reduction performance of one-dimensional platinum cobalt alloy nanowires prepared in examples 3-5;

FIG. 7 shows the oxygen reduction stability of one-dimensional platinum nickel alloy nanowires (Pt ₃ Ni NWs) prepared in example 1;

FIG. 8 is an oxygen reduction performance of one-dimensional platinum cobalt alloy nanowires prepared in example 3 with catalysts prepared at 200 ℃ only and 300 ℃ only;

fig. 9 shows the oxygen reduction performance of the one-dimensional platinum cobalt alloy nanowires prepared in example 3 and nanowire catalysts prepared by other processes.

Detailed Description

The invention will now be described in detail with reference to the drawings and specific examples.

A self-assembly preparation method of a platinum-based nanowire electrocatalytic material is shown in fig. 1, and comprises the following steps:

s1, uniformly mixing platinum metal precursor salt and transition metal precursor salt to obtain precursor powder, or uniformly mixing the platinum metal precursor salt, the transition metal precursor salt and a carrier to obtain precursor powder;

S2, placing the precursor powder in a flowing reduction atmosphere, and heating and reducing the platinum noble metal;

And S3, the replacement reaction atmosphere is a mixed flowing atmosphere of reducing gas/inert gas, the transition metal and the noble metal are reduced together by heating and raising the temperature, and the nanowire metal material is formed by self-assembly.

In some specific embodiments, in step S1, the transition metal precursor salt is at least one transition metal selected from iron, nickel, copper, or cobalt.

In some specific embodiments, in step S1, the molar ratio of platinum to transition metal in the platinum precursor salt to the transition metal precursor salt is (1-3): 1.

In some specific embodiments, the platinum precursor salt is a chloroplatinic acid salt, such as potassium chloroplatinic acid.

In some specific embodiments, the transition metal precursor salt is selected from acetylacetonates, such as iron acetylacetonate, nickel acetylacetonate, copper acetylacetonate, or cobalt acetylacetonate.

In some specific embodiments, in step S1, a self-assembled metal nanowire with high conductivity and large exposed active area of metal can be formed without adding a carrier, so that the oxygen reduction electrochemical performance of the catalyst is greatly improved. The addition of a carrier can form a supported self-assembled metal nanowire.

In some specific embodiments, the support is selected from porous carbon powder or titanium dioxide nanoparticles, and the like.

In some embodiments, the carrier is used in an amount of 80 to 120mg/0.1mmol Pt.

In some specific embodiments, in step S1, the mixing of the platinum metal precursor salt and the transition metal precursor salt, or the mixing of the platinum metal precursor salt, the transition metal precursor salt, and the carrier is achieved by grinding.

In some preferred embodiments, to prevent phase separation during the reduction process, repeated grinding in a natural agate mortar is required to achieve a uniform solid powder color.

In some specific embodiments, in step S2, the reducing gas used in the reducing atmosphere is hydrogen.

In some specific embodiments, in step S2, the reduction temperature is 100-200 ℃ and the reduction time is 10-180min in the heating reduction.

In step S2, a portion of the platinum precursor is pre-reduced to form nanoclustered platinum particles as platinum seeds to provide sites for directional attachment for subsequent nucleation growth of the transition metal.

In some specific embodiments, in step S2, the heated reduction is achieved by placing the precursor powder in a quartz boat and then heating it in a quartz tube.

In some preferred embodiments, the precursor powder should be capable of being heated uniformly and sufficiently in contact with the reactant gases so that it is desirable to lay flat on the quartz boat as much as possible.

In some preferred embodiments, in step S2, the air in the reactor is also purged with an inert gas prior to heating the reaction. More preferably, the inert gas is preferably argon, and the inert gas needs to be introduced for 20-30 min to empty the air in the cavity, so as to prevent the metal precursor from being oxidized in the subsequent temperature rising stage.

In some specific embodiments, in step S3, in the mixed flowing atmosphere, the reducing gas used is hydrogen, and the inert gas used is preferably argon.

In some more specific embodiments, the content of the reducing gas in the mixed flowing atmosphere is 5-10vol%.

In some specific embodiments, in step S3, the heating temperature is 250-300 ℃ and the reduction time is 0.5-6h during the self-assembly process.

In step S3, the transition metal is co-reduced with the remaining platinum precursor, preferentially continuing to nucleate on the pre-reduced platinum nanoclusters, and directionally growing into platinum-based alloy nanowires. Based on the different addition of precursor salts, pure platinum nanowires, platinum cobalt nanowires, platinum nickel nanowires, platinum iron nanowires, and platinum copper nanowires can be prepared.

In some specific embodiments, in step S3, the reduced product is dispersed in ethanol and subjected to ultrasonic washing to obtain the nanowire metal material.

The whole self-assembly preparation process of the invention does not involve any organic end capping agent, does not introduce organic substances, avoids the influence of the organic substances on the catalytic performance, does not need a complex washing process, disperses the reduction product in deionized water (18.2 megaohms) and absolute ethyl alcohol, can remove residual precursor salt after 2 times of centrifugation by a centrifuge, has simple storage, and can be preserved for a long time after redispersing the product in absolute ethyl alcohol.

Use of a platinum-based nanowire electrocatalyst material comprising using the platinum-based nanowire electrocatalyst material as an electrode material for the preparation of a fuel cell.

The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.

Oxygen reduction test the prepared catalyst was formulated as a homogeneous ink of 5mg catalyst, 4mL deionized water, 1mL isopropyl alcohol, and 25. Mu.L Nafion solution. An ink containing about 4. Mu.g of Pt was dropped onto a rotating disk electrode of 0.196cm ², dried naturally, and tested. The three electrode test method was used to perform a voltammetric cyclic scan test of 0.05-1.0V in 0.1MHClO ₄ saturated with Ar and a polarization curve test of 0-1.1V in 0.1M HClO ₄ saturated with O ₂.

Accelerated stability test 30,000 cycles of accelerated cycle test were performed at a voltage ranging from 0.6 to 1.0V, followed by oxygen reduction performance test.

Fuel cell testing the prepared ink was sprayed on the proton exchange membrane as cathode catalyst (0.1 mg _Ptcm^-2) and 40wt% commercial Pt/C catalyst as anode catalyst (0.05 mg _Pt cm^-2) on the other side of the proton exchange membrane. MEA assembly was performed using a 235 μm gas diffusion layer (28 bc, sgl Carbon) and the fuel cell test system was Scribner 850,850, 850e Fuel Cell Test System. Test conditions were 80℃and 0.5L min ^-1H₂,0.5L min^-1O₂,2L min^-1 air.

Example 1:

A self-assembled one-dimensional platinum nickel alloy nanowire (Pt ₃ Ni NWs) is prepared by the following steps:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄) and 8.56mg (0.033 mmol) of nickel acetylacetonate (Ni (acac) ₂) are weighed, placed in an agate mortar for full grinding, and uniformly mixed to obtain precursor powder;

2) Spreading the precursor powder in a quartz boat, putting the quartz boat in a quartz tube and putting the quartz tube in a tube furnace;

3) Argon is introduced into the quartz tube for 20 minutes, air in the quartz tube is discharged, and metal is prevented from being oxidized in the heating process;

4) Switching the gas to pure hydrogen at a flow rate of 200 ml/min, and simultaneously raising the temperature of the tube furnace from room temperature to 200 ℃ at a temperature raising rate of 5 ℃/min, and preserving the temperature for 10min;

5) The gas was switched to a hydrogen/argon (v/v=5/95) mixture at a flow rate of 200 ml/min. Meanwhile, the temperature of the tube furnace is increased from 200 ℃ to 300 ℃ at the temperature increasing rate of 5 ℃ per minute, and after heat preservation for 0.5h, the tube furnace is naturally cooled to room temperature;

6) After the reaction is finished, switching the gas to argon, evacuating residual hydrogen in the quartz tube, and taking out the reduced solid powder product;

7) Washing, adding ethanol and deionized water for ultrasonic dispersion, centrifuging, and repeating twice. And dispersing the washed sample into a small amount of absolute ethyl alcohol for preservation, and obtaining the self-assembled one-dimensional platinum nickel alloy nanowire (Pt ₃ Ni NWs).

Example 2:

a self-assembled one-dimensional platinum copper alloy nanowires (PtCu NWs), the method of preparation comprising the steps of:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄) and 26.17mg (0.1 mmol) of copper acetylacetonate (Cu (acac) ₂) are weighed, placed in an agate mortar for full grinding, and uniformly mixed to obtain precursor powder;

4) Switching the gas to pure hydrogen at a flow rate of 200 ml/min, and simultaneously raising the temperature of the tube furnace from room temperature to 150 ℃ at a temperature raising rate of 5 ℃/min, and preserving the temperature for 30min;

5) The gas was switched to a hydrogen/argon (v/v=5/95) mixture at a flow rate of 200 ml/min. Meanwhile, the temperature of the tube furnace is increased from 150 ℃ to 250 ℃ at the temperature increasing rate of 5 ℃ per minute, and after heat preservation for 1 hour, the tube furnace is naturally cooled to room temperature;

Example 3:

a self-assembled one-dimensional platinum cobalt alloy nanowire (PtCo NWs), the method of preparation comprising the steps of:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄) and 25.72mg (0.1 mmol) of cobalt acetylacetonate (Co (acac) ₂) are weighed, and placed in an agate mortar for full grinding, and uniformly mixed to obtain precursor powder;

4) Switching the gas to pure hydrogen at a flow rate of 200 ml/min, and simultaneously raising the temperature of the tube furnace from room temperature to 200 ℃ at a temperature raising rate of 5 ℃/min, and preserving the heat for 120min;

5) The gas was switched to a hydrogen/argon (v/v=5/95) mixture at a flow rate of 200 ml/min. Meanwhile, the temperature of the tube furnace is increased from 200 ℃ to 300 ℃ at the temperature increasing rate of 5 ℃ per minute, and after heat preservation for 2 hours, the tube furnace is naturally cooled to room temperature;

Example 4:

A self-assembled one-dimensional platinum cobalt alloy nanowire (Pt ₂ Co NWs) is prepared by the following steps:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄) and 12.86mg (0.05 mmol) of cobalt acetylacetonate (Co (acac) ₂) are weighed, placed in an agate mortar for full grinding, and uniformly mixed to obtain precursor powder;

5) The gas was switched to a hydrogen/argon (v/v=5/95) mixture at a flow rate of 200 ml/min. Meanwhile, the temperature of the tube furnace is increased from 200 ℃ to 300 ℃ at the temperature increasing rate of 5 ℃ per minute, and after heat preservation for 3 hours, the tube furnace is naturally cooled to room temperature;

Example 5:

A self-assembled one-dimensional platinum cobalt alloy nanowire (Pt ₃ Co NWs) is prepared by the following steps:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄) and 8.57mg (0.033 mmol) of cobalt acetylacetonate (Co (acac) ₂) are weighed, placed in an agate mortar for full grinding, and uniformly mixed to obtain precursor powder;

7) Washing, adding ethanol and deionized water for ultrasonic dispersion, centrifuging, and repeating twice. And dispersing the washed sample into a small amount of absolute ethyl alcohol for preservation, and obtaining the self-assembled one-dimensional platinum cobalt alloy nanowire (Pt ₃ Co NWs).

Example 6:

a self-assembled one-dimensional platinum-iron alloy nanowire (PtFe NWs) prepared by a method comprising the steps of:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄) and 35.32mg (0.1 mmol) of ferric acetylacetonate (Fe (acac) ₃) precursor are weighed, and are fully ground in an agate mortar and uniformly mixed to obtain precursor powder;

4) Switching the gas to pure hydrogen at a flow rate of 200 ml/min, and simultaneously raising the temperature of the tube furnace from room temperature to 200 ℃ at a temperature raising rate of 5 ℃/min, and preserving the heat for 60min;

7) Washing, adding ethanol and deionized water for ultrasonic dispersion, centrifuging, and repeating twice. And dispersing the washed sample into a small amount of absolute ethyl alcohol for preservation, thus obtaining the self-assembled one-dimensional platinum cobalt alloy nanowire (PtFe NWs).

Example 7A porous carbon-supported one-dimensional platinum cobalt nanowires (PtCo/C NWs) were prepared by the following steps:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄), 25.72mg (0.1 mmol) of cobalt acetylacetonate (Co (acac) ₂) precursor and 100mgV_XC72 porous carbon black are weighed, fully ground in an agate mortar, and uniformly mixed to obtain precursor powder;

4) Switching the gas to pure hydrogen at a flow rate of 200 ml/min, and simultaneously raising the temperature of the tube furnace from room temperature to 180 ℃ at a temperature raising rate of 5 ℃/min, and preserving heat for 180min;

5) The gas was switched to a hydrogen/argon (v/v=5/95) mixture at a flow rate of 200 ml/min. Meanwhile, the temperature of the tube furnace is increased from 180 ℃ to 300 ℃ at the temperature increasing rate of 5 ℃ per minute, and after heat preservation for 6 hours, the tube furnace is naturally cooled to room temperature;

7) Washing, adding ethanol and deionized water for ultrasonic dispersion, centrifuging, and repeating twice. And dispersing the washed sample into a small amount of absolute ethyl alcohol for preservation, and obtaining the porous carbon-supported one-dimensional platinum cobalt nanowire (PtCo/C NWs).

Example 8:

a porous carbon supported one-dimensional platinum iron nanowires (PtFe/C NWs), a method of making and oxygen reduction applications comprising the steps of:

1) 41.51mg (0.1 mmol) of potassium chloroplatinite (K ₂PtCl₄), 35.32mg (0.1 mmol) of ferric acetylacetonate (Fe (acac) ₃) precursor and 100mg of porous carbon black are weighed, fully ground in an agate mortar, and uniformly mixed to obtain precursor powder;

4) Switching the gas to pure hydrogen at a flow rate of 200 ml/min, and simultaneously raising the temperature of the tube furnace from room temperature to 200 ℃ at a temperature raising rate of 5 ℃/min, and preserving heat for 180min;

5) The gas was switched to a hydrogen/argon (v/v=5/95) mixture at a flow rate of 200 ml/min. Meanwhile, the temperature of the tube furnace is increased from 200 ℃ to 250 ℃ at the temperature increasing rate of 5 ℃ per minute, and after heat preservation for 5 hours, the tube furnace is naturally cooled to room temperature;

FIG. 1 is a process flow diagram of a self-assembly preparation method of a platinum-based nanowire electrocatalytic material, relating to a two-part reduction method, with simple process, easy operation and industrial scale-up. FIG. 2 is a morphology and structural characterization of platinum-based alloy nanowires. Fig. 2-1 is a one-dimensional platinum nickel alloy nanowire TEM structural characterization prepared in example 1. Fig. 2-2 is a one-dimensional platinum copper alloy nanowire TEM structural characterization prepared in example 2. FIGS. 2-3 are TEM structural representations of one-dimensional platinum cobalt alloy nanowires prepared in example 3. Fig. 2-4 are structural representations of one-dimensional platinum copper alloy nanowire TEM prepared in example 7, which shows that the preparation method provided by the invention is suitable for synthesizing various one-dimensional platinum-based binary nanowires.

FIG. 3 is a TEM and particle size distribution diagram of one-dimensional PtCo alloy nanowires of different proportions prepared in examples 3-5. The PtCo alloy nanowires with different proportions have diameters of 3.47nm,5.14nm and 4.15nm, respectively. The preparation method is applicable to synthesis of platinum-based alloy nanowires with different proportions.

FIG. 4 shows the XRD of the one-dimensional PtCo alloy nanowires prepared in examples 3-5, and the Co content of the nanowires prepared in different proportions and different precursor ratios. XRD shows that the prepared nanowires are single-phase alloys, and the Co proportion of the nanowires can be obtained from EDS (electronic data storage system) and is 44%, 15% and 8% respectively. EDS results show that when the precursor molar ratio is Pt: co=1:1, the molar ratio of the obtained nanowires is 1.3:1 and is close to 1:1, and the nanowire alloying effect is best. When the precursor molar ratio Pt is Co=2:1 or 3:1, the content of Pt in the nanowire is very high, the content of Co atoms is very small, and the nanowire is PtCo alloy mainly containing metal Pt.

In fig. 5, 5-1 and 5-2 correspond to the porous carbon-supported one-dimensional platinum cobalt nanowire prepared in example 7 and the porous carbon-supported one-dimensional platinum iron nanowire prepared in example 8, respectively, which indicate that the preparation method of the invention is not only suitable for self-assembled nanowires, but also suitable for the situation of carriers.

FIG. 6 shows the electrocatalytic oxygen reduction performance of different proportions of Pt-Co nanowires prepared in examples 3-5. Wherein the mass activity of Pt ₁Co₁ nanowires is 8.6 times that of commercial platinum carbon. Detailed data showing excellent oxygen reduction performance are shown in table 1.

TABLE 1 comparison of oxygen reduction electrocatalytic Mass Activity and specific Activity of platinum cobalt alloy nanowire catalysts in different proportions

FIG. 7 shows the result of electrocatalytic oxygen reduction stability of Pt ₃Ni₁ nanowires prepared in example 1. Through 30,000 circles of acceleration tests, the specific activity is only 25% lost, the mass activity is only 30% lost, and the oxygen reduction activity and the stability are excellent. The detailed data are shown in table 2.

TABLE 2 comparison of Mass Activity and specific Activity of Pt ₃ Ni nanowire catalysts before and after oxygen reduction for thirty-thousand cycles of acceleration stability test

Fig. 8 is a comparison of oxygen reduction catalytic performance of the PtCo nanowire prepared in example 3 with the PtCo nanowire metal material prepared by reduction at 200 ℃ only and 300 ℃ only. The mass activity of the PtCo alloy nanowire catalyst prepared by the two-step reduction method is 5.29 and 3.64 times of that of PtCo alloy nanowire reduced at 200 ℃ and 300 ℃ only. The oxygen reduction activity of the nanowire prepared by the two-step reduction method is excellent. The detailed data are shown in table 3.

TABLE 3 comparison of the mass Activity and specific Activity of two-step Pt ₁Co₁ and one-step Pt ₁Co₁

FIG. 9 shows the results of testing PtCo nanowires and commercial Pt/C catalysts in a fuel cell, prepared in example 3. The fuel cell test result shows that the mass activity of the PtCo nanowire is 2.35 times of that of the commercial Pt/C nanowire, and more notably, after 30,000 circles of accelerated life test, the mass activity of the platinum-cobalt nanowire catalyst prepared by the method still remains 63.8%, the maximum power density still remains 80.88%, but the mass activity of the commercial Pt/C nanowire only remains 30.0%, and the power density also only remains 39.66%. The platinum cobalt nanowire prepared by the method disclosed by the invention keeps excellent activity and stability in a fuel cell test. The detailed data are shown in table 4.

TABLE 4 comparison of fuel cell mass activity and power density for Pt ₁Co₁ versus commercial Pt/C

The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.

Claims

1. A method for self-assembling a platinum-based nanowire electrocatalytic material, characterized in that it comprises:

Platinum-based nanowire electrocatalytic materials are obtained by mixing platinum precursor salts with transition metal precursor salts, heating and reducing them in a reducing gas, and then heating and self-assembling them in a diluted reducing gas.

In the heating reduction process, the reduction temperature is 100~200℃; in the heating self-assembly process, the heating temperature is 250~300℃.

The reducing gas is hydrogen; the diluting reducing gas is a mixture of hydrogen and an inert gas.

The hydrogen content in the diluted reducing gas is 5-10 vol%.

In the transition metal precursor salt, the transition metal is selected from at least one of iron, nickel, copper or cobalt;

In the platinum precursor salt and the transition metal precursor salt, the molar ratio of platinum to transition metal is (1~3):1;

The platinum precursor salt is chloroplatinate, and the transition metal precursor salt is selected from acetylacetone salt.

2. The self-assembly preparation method of platinum-based nanowire electrocatalytic material according to claim 1, characterized in that, during the mixing process of the platinum precursor salt and the transition metal precursor salt, it further includes mixing with the support.

3. The self-assembly preparation method of platinum-based nanowire electrocatalytic material according to claim 2, characterized in that the support is selected from porous carbon powder or titanium dioxide nanoparticles, and the amount used is 80~120mg/0.1mmol Pt.

4. A platinum-based nanowire electrocatalytic material, characterized in that it is prepared by the method described in any one of claims 1 to 3.

5. An application of the platinum-based nanowire electrocatalytic material as described in claim 4, characterized in that the platinum-based nanowire electrocatalytic material is used as an electrode material in the preparation of fuel cells.