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

Abstract

The application 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 of the platinum-based nanowire electrocatalytic material in an oxygen reduction reaction. The preparation method comprises the following steps: mixing a platinum precursor salt and a transition metal precursor salt, heating and reducing in a reducing gas, and then heating and self-assembling in a dilute reducing gas to obtain the platinum-based nanowire electrocatalytic material. In the heating and reducing, the reduction temperature is 100-200 DEG C. In the heating and self-assembling, the heating temperature is 250-300 DEG C. 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 capping reagent. Under the auxiliary action of the reducing gas, the metal nanowire is self-assembled and grown through the different adsorption energies of different crystal surfaces to the gas, and can be used for the oxygen reduction reaction and has excellent catalytic performance.

Description

Technical Field

[0001] This invention belongs to the field of oxygen reduction catalytic materials technology, and relates to a platinum-based nanowire electrocatalytic material, its self-assembly preparation method, and its application in oxygen reduction reactions. Background Technology

[0002] Metal nanowires possess excellent properties such as high electrical conductivity, unique optical characteristics, and high aspect ratio. Compared with nanoparticles, one-dimensional platinum-based nanowires have a larger aspect ratio, which is beneficial for constructing self-supporting 3D network structures, providing continuous electron transport paths, reducing charge transfer resistance, improving electrode conductivity and kinetics, and exhibiting excellent performance in electrocatalysis.

[0003] To achieve the preparation of nanowires, patent CN111313045 discloses a platinum-copper alloy nanowire, its preparation method, and its applications. Although this platinum-copper alloy nanowire exhibits strong catalytic activity and good stability as an anode catalyst for methanol fuel cells, the catalyst is prepared using a hydrothermal method, making large-scale industrialization difficult. Furthermore, this patent does not mention methods for preparing other transition metals and platinum to synthesize platinum-based nanowire catalysts, lacking universality. Patent CN105081341A provides a liquid-phase synthesis method for obtaining platinum nanowire networks. While the preparation method is simple and fast, it requires the use of organic surfactants, which is detrimental to catalytic activity and necessitates further treatment to remove the surfactants. Currently, one-dimensional platinum-based nanowires are mainly prepared in the liquid phase, introducing surfactants during the preparation process, and are difficult to scale up for industrialization.

[0004] Therefore, there is an urgent need to develop a large-scale platinum-based nanowire catalyst with a clean surface and high versatility for use as a cathode catalyst in fuel cells. Summary of the Invention

[0005] The purpose of this invention is to provide a platinum-based nanowire electrocatalytic material, its self-assembly preparation method, and its application in the oxygen reduction reaction. The preparation process of this invention is simple, and the growth of multi-element metal nanowires can be controlled without complex organic end-capping reagents. With the assistance of a reducing gas, metal nanowires are self-assembled and grown due to the different adsorption energies of different crystal faces, enabling their use in the oxygen reduction reaction with excellent catalytic performance.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] The first aspect of this invention provides a method for the self-assembly preparation of platinum-based nanowire electrocatalytic materials, comprising:

[0008] 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.

[0009] In the heating reduction process, the reduction temperature is 100–200°C; in the heating self-assembly process, the heating temperature is 250–300°C.

[0010] Furthermore, the reducing gas is hydrogen.

[0011] Furthermore, the diluting reducing gas is a mixture of hydrogen and an inert gas.

[0012] Furthermore, the hydrogen content is 5-10 vol%.

[0013] Furthermore, in the transition metal precursor salt, the transition metal is selected from at least one of iron, nickel, copper, or cobalt.

[0014] Furthermore, in the platinum precursor salt and the transition metal precursor salt, the molar ratio of platinum to transition metal is (1-3):1.

[0015] Furthermore, the platinum precursor salt is a chloroplatinite, and the transition metal precursor salt is selected from acetylacetone salts.

[0016] Furthermore, the mixing process of the platinum precursor salt and the transition metal precursor salt also includes mixing with the support.

[0017] Furthermore, the carrier is selected from porous carbon powder or titanium dioxide nanoparticles, and the amount used is 80-120 mg / 0.1 mmol Pt.

[0018] A second aspect of the present invention provides a platinum-based nanowire electrocatalytic material, which is prepared by the method described above.

[0019] A third aspect of the present invention provides an application of a platinum-based nanowire electrocatalytic material, including using the platinum-based nanowire electrocatalytic material as an electrode material in the preparation of a fuel cell.

[0020] This invention utilizes the self-assembly properties of metals in a hydrogen environment to achieve the synthesis of morphology-controllable pure platinum / binary platinum-based alloy nanowire materials through a simple reduction reaction. Simultaneously, it avoids the influence of organic end-capping agents on the catalytic performance of metal nanomaterials, achieving the goal of preparing nanowire materials with clean surfaces. This method is universal and can be used for the synthesis of nanowires of different platinum-based metals. The prepared platinum-based alloy nanowire materials exhibit excellent electrocatalytic oxygen reduction performance due to their low noble metal content and exposed high-index crystal facets. Furthermore, compared with traditional liquid-phase synthesis, this method is more suitable for large-scale industrial production.

[0021] Compared with the prior art, the present invention has the following characteristics:

[0022] 1) The self-assembled metal nanowires prepared in this invention have a low proportion of noble metal platinum, and the synergistic effect of transition metals makes the catalyst have high electrocatalytic oxygen reduction activity and greatly reduces the catalyst cost.

[0023] 2) This invention uses a gas-phase reaction, which is different from the traditional wet chemical method. The preparation process is simple and suitable for large-scale mass production.

[0024] 3) The preparation process of this invention does not require the introduction of any end-capping agent, the catalyst product surface is clean, no special treatment is required, the metal exposure area is large, exhibiting excellent catalytic activity, and it is green and environmentally friendly, reducing production costs;

[0025] 4) This invention has high versatility. It is applicable not only to the preparation of self-assembled nanowires of pure platinum metal, but also to the self-assembled synthesis of alloy nanowires with different transition metal compositions and proportions. Attached Figure Description

[0026] Figure 1 This is a process flow diagram of a self-assembly preparation method for a platinum-based nanowire electrocatalytic material according to the present invention;

[0027] Figure 2 Transmission electron microscopy images of the platinum-based nanowire electrocatalytic materials prepared in this invention: (1) One-dimensional platinum-nickel alloy nanowires (Pt3Ni 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; (4) One-dimensional platinum-iron alloy nanowires (PtFe NWs) prepared in Example 6;

[0028] Figure 3 Transmission electron microscopy images of the one-dimensional platinum-cobalt alloy nanowires prepared for this invention: (1) Pt:Co = 1:1, Example 3; (2) Pt:Co = 2:1, Example 4; (3) Pt:Co = 3:1, Example 5; Particle size distribution diagram of the one-dimensional platinum-cobalt alloy nanowires prepared for this invention: (4) Pt:Co = 1:1, Example 3; (5) Pt:Co = 2:1, Example 4; (6) Pt:Co = 3:1, Example 5;

[0029] Figure 4 XRD and EDS elemental distributions of the one-dimensional platinum-cobalt alloy nanowires prepared in Examples 3-5;

[0030] Figure 5 Transmission electron microscopy images of porous carbon-supported one-dimensional platinum-based nanowires prepared for this invention: (1) PtCo nanowires, Example 7; (2) PtFe nanowires, Example 8;

[0031] Figure 6The oxygen reduction properties of the one-dimensional platinum-cobalt alloy nanowires prepared in Examples 3-5;

[0032] Figure 7 The oxygen reduction stability of the one-dimensional platinum-nickel alloy nanowires (Pt3Ni NWs) prepared in Example 1;

[0033] Figure 8 The oxygen reduction performance of the one-dimensional platinum-cobalt alloy nanowires prepared in Example 3 and the catalysts prepared only at 200°C and only at 300°C;

[0034] Figure 9 The oxygen reduction performance of the one-dimensional platinum-cobalt alloy nanowires prepared in Example 3 and nanowire catalysts prepared by other processes is compared. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0036] A method for the self-assembly preparation of platinum-based nanowire electrocatalytic materials, such as Figure 1 As shown, it includes the following steps:

[0037] S1: Mix platinum metal precursor salt and transition metal precursor salt evenly to obtain precursor powder, or mix platinum metal precursor salt, transition metal precursor salt, and carrier evenly to obtain precursor powder.

[0038] S2: Place the precursor powder in a flowing reducing atmosphere and heat to reduce platinum precious metal;

[0039] S3: The displacement reaction atmosphere is a mixed flow atmosphere of reducing gas / inert gas. Heating and raising the temperature will reduce the transition metal and noble metal together, and self-assemble them to form nanowire metal materials.

[0040] In some specific embodiments, in step S1, the transition metal in the transition metal precursor salt is selected from at least one of iron, nickel, copper or cobalt.

[0041] In some specific embodiments, in step S1, the molar ratio of platinum to transition metal in the platinum precursor salt and transition metal precursor salt is (1-3):1.

[0042] In some specific embodiments, the platinum precursor salt is a chloroplatinate, such as potassium chloroplatinate.

[0043] In some specific embodiments, the transition metal precursor salt is selected from acetylacetone salts, such as iron acetylacetone, nickel acetylacetone, copper acetylacetone, or cobalt acetylacetone.

[0044] In some specific embodiments, in step S1, without adding a support, self-supported, self-assembled metal nanowires can be formed, exhibiting high conductivity and a large exposed active area of ​​metal, thus significantly improving the oxygen reduction electrochemical performance of the catalyst. Adding a support can form supported, self-assembled metal nanowires.

[0045] In some specific embodiments, the carrier is selected from porous carbon powder or titanium dioxide nanoparticles, etc.

[0046] In some specific embodiments, the amount of the carrier used is 80–120 mg / 0.1 mmol Pt.

[0047] 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.

[0048] In some preferred embodiments, to prevent phase separation during the reduction process, the solid powder needs to be repeatedly ground in a natural agate mortar until the color is uniform.

[0049] In some specific embodiments, in step S2, the reducing gas used in the reducing atmosphere is hydrogen.

[0050] In some specific embodiments, in step S2, the reduction temperature is 100-200℃ and the reduction time is 10-180min during the heating reduction.

[0051] In step S2, a portion of the platinum precursor is pre-reduced to form nanoclusters of platinum particles, which serve as platinum seeds and provide directional connection sites for the subsequent nucleation and growth of transition metals.

[0052] In some specific embodiments, in step S2, the precursor powder is placed in a quartz boat and then heated in a quartz tube to achieve thermal reduction.

[0053] In some preferred embodiments, the precursor powder should be able to be heated uniformly and fully contacted with the reactant gas, so it needs to be spread as flatly as possible on the quartz boat.

[0054] In some preferred embodiments, in step S2, before heating the reaction, the air in the reactor needs to be purged with an inert gas. More preferably, the inert gas is argon, which needs to be introduced for 20-30 minutes to purge the air inside the chamber and prevent the metal precursor from being oxidized during the subsequent heating stage.

[0055] In some specific embodiments, in step S3, the reducing gas used in the mixed flow atmosphere is hydrogen, and the inert gas used is preferably argon.

[0056] In some more specific embodiments, the reducing gas content in the mixed flowing atmosphere is 5–10 vol%.

[0057] In some specific embodiments, in step S3, during the self-assembly process, the heating temperature is 250-300℃ and the reduction time is 0.5-6h.

[0058] In step S3, the transition metal and the remaining platinum precursor are co-reduced, preferentially continuing nucleation on the pre-reduced platinum nanoclusters, and directionally growing into platinum-based alloy nanowires. Depending on the precursor salt added, pure platinum nanowires, platinum-cobalt nanowires, platinum-nickel nanowires, platinum-iron nanowires, and platinum-copper nanowires can be prepared.

[0059] In some specific embodiments, in step S3, the reduction product is dispersed in ethanol and ultrasonically washed to obtain nanowire metal materials.

[0060] The entire self-assembly preparation process of this invention does not involve any organic end-capping agents, does not introduce organic substances, and avoids the influence of organic matter on catalytic performance; and does not require a complicated washing process. The reduction product is dispersed in deionized water (18.2 megohms) and anhydrous ethanol, and centrifuged twice to remove residual precursor salts; storage is simple. The product can be redispersed in anhydrous ethanol for long-term preservation.

[0061] An application of a platinum-based nanowire electrocatalytic material includes using the platinum-based nanowire electrocatalytic material as an electrode material in the preparation of fuel cells.

[0062] This embodiment is implemented based on the technical solution of the present invention, and provides detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiment.

[0063] Oxygen reduction reaction test: The prepared catalyst was mixed with a homogeneous ink: 5 mg catalyst, 4 mL deionized water, 1 mL isopropanol, and 25 μL Nafion solution. A drop of ink containing approximately 4 μg Pt was added to a 0.196 cm⁻¹ solution. 2 The sample was dried naturally on a rotating disk electrode before testing. A three-electrode testing method was used, with voltammetric cyclic scanning tests from 0.05 to 1.0 V in Ar-saturated 0.1 M HClO4 and polarization curve tests from 0 to 1.1 V in O2-saturated 0.1 M HClO4.

[0064] Accelerated stability testing: 30,000 accelerated cycling tests were conducted within a voltage range of 0.6-1.0V, followed by oxygen reduction performance testing.

[0065] Fuel cell testing: The prepared ink was sprayed onto a proton exchange membrane as a cathode catalyst (0.1 mg). Pt cm-2 ), using 40wt% commercial Pt / C catalyst as the anode catalyst (0.05mg) Pt cm -2 The coating was sprayed onto the other side of the proton exchange membrane. A 235μm gas diffusion layer (28BC, SGL Carbon) was used for MEA assembly. The fuel cell testing system was a Scribner 850e Fuel Cell Test System. Test conditions: 80℃, 0.5L min. -1 H2, 0.5L min -1 O2, 2L min -1 Air.

[0066] Example 1:

[0067] A self-assembled one-dimensional platinum-nickel alloy nanowire (Pt3Ni NWs) is prepared by the following steps:

[0068] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4) and 8.56 mg (0.033 mmol) nickel acetylacetone (Ni(acac)2), grind them thoroughly in an agate mortar, mix them evenly, and obtain the precursor powder;

[0069] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0070] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0071] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 200℃ at a heating rate of 5℃ / min and hold for 10 min.

[0072] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 200°C to 300°C at a rate of 5°C / min, hold at that temperature for 0.5 h, and then allow it to cool naturally to room temperature.

[0073] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0074] 7) Washing: Add ethanol and deionized water and sonicate to disperse, then centrifuge, repeating twice. Disperse the washed sample in at least a small amount of anhydrous ethanol and store to obtain self-assembled one-dimensional platinum-nickel alloy nanowires (Pt3Ni NWs).

[0075] Example 2:

[0076] A self-assembled one-dimensional platinum-copper alloy nanowire (PtCu NWs) is prepared by the following steps:

[0077] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4) and 26.17 mg (0.1 mmol) copper acetylacetone (Cu(acac)2), grind them thoroughly in an agate mortar, mix them evenly, and obtain the precursor powder;

[0078] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0079] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0080] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 150°C at a heating rate of 5°C / min and hold for 30 min.

[0081] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 150°C to 250°C at a rate of 5°C / min, hold for 1 hour, and then allow it to cool naturally to room temperature.

[0082] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0083] 7) Washing: Add ethanol and deionized water and sonicate to disperse, then centrifuge, repeating twice. Disperse the washed sample in at least a small amount of anhydrous ethanol and store to obtain self-assembled one-dimensional platinum-nickel alloy nanowires (Pt3Ni NWs).

[0084] Example 3:

[0085] A self-assembled one-dimensional platinum-cobalt alloy nanowire (PtCo NWs) is prepared by the following steps:

[0086] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4) and 25.72 mg (0.1 mmol) cobalt acetylacetonate (Co(acac)2), grind them thoroughly in an agate mortar, mix them evenly, and obtain the precursor powder;

[0087] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0088] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0089] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 200℃ at a heating rate of 5℃ / min and hold for 120 min.

[0090] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 200°C to 300°C at a rate of 5°C / min, hold for 2 hours, and then allow it to cool naturally to room temperature.

[0091] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0092] 7) Washing: Add ethanol and deionized water and sonicate to disperse, then centrifuge, repeating twice. Disperse the washed sample in at least a small amount of anhydrous ethanol and store to obtain self-assembled one-dimensional platinum-nickel alloy nanowires (Pt3Ni NWs).

[0093] Example 4:

[0094] A self-assembled one-dimensional platinum-cobalt alloy nanowire (Pt2Co NWs) is prepared by the following steps:

[0095] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4) and 12.86 mg (0.05 mmol) cobalt acetylacetonate (Co(acac)2), grind them thoroughly in an agate mortar, mix them evenly, and obtain the precursor powder;

[0096] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0097] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0098] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 200℃ at a heating rate of 5℃ / min and hold for 120 min.

[0099] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 200°C to 300°C at a rate of 5°C / min, hold for 3 hours, and then allow it to cool naturally to room temperature.

[0100] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0101] 7) Washing: Add ethanol and deionized water and sonicate to disperse, then centrifuge, repeating twice. Disperse the washed sample in at least a small amount of anhydrous ethanol and store to obtain self-assembled one-dimensional platinum-nickel alloy nanowires (Pt3Ni NWs).

[0102] Example 5:

[0103] A self-assembled one-dimensional platinum-cobalt alloy nanowire (Pt3Co NWs) is prepared by the following steps:

[0104] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4) and 8.57 mg (0.033 mmol) cobalt acetylacetonate (Co(acac)2), grind them thoroughly in an agate mortar, mix them evenly, and obtain the precursor powder;

[0105] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0106] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0107] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 200℃ at a heating rate of 5℃ / min and hold for 120 min.

[0108] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 200°C to 300°C at a rate of 5°C / min, hold for 3 hours, and then allow it to cool naturally to room temperature.

[0109] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0110] 7) Washing: Add ethanol and deionized water and sonicate to disperse, then centrifuge, repeating twice. Disperse the washed sample in at least a small amount of anhydrous ethanol and store to obtain self-assembled one-dimensional platinum-cobalt alloy nanowires (Pt3Co NWs).

[0111] Example 6:

[0112] A self-assembled one-dimensional platinum-iron alloy nanowire (PtFe NWs) is prepared by the following steps:

[0113] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4) and 35.32 mg (0.1 mmol) iron acetylacetone (Fe(acac)3) precursor, grind them thoroughly in an agate mortar, mix them evenly, and obtain precursor powder.

[0114] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0115] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0116] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 200℃ at a heating rate of 5℃ / min and hold for 60 min.

[0117] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 200°C to 300°C at a rate of 5°C / min, hold for 2 hours, and then allow it to cool naturally to room temperature.

[0118] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0119] 7) Washing: Add ethanol and deionized water, sonicate to disperse, then centrifuge, repeat twice. Disperse the washed sample in at least a certain amount of anhydrous ethanol and store to obtain self-assembled one-dimensional platinum-cobalt alloy nanowires (PtFe NWs).

[0120] Example 7: A porous carbon-supported one-dimensional platinum-cobalt nanowire (PtCo / C NWs), the preparation method of which includes the following steps:

[0121] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4), 25.72 mg (0.1 mmol) cobalt acetylacetonate (Co(acac)2) precursor and 100 mg V_XC72 porous carbon black, place them in an agate mortar and grind them thoroughly until they are mixed evenly to obtain precursor powder;

[0122] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0123] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0124] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 180℃ at a heating rate of 5℃ / min and hold for 180 min.

[0125] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 180°C to 300°C at a rate of 5°C / min, hold for 6 hours, and then allow it to cool naturally to room temperature.

[0126] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0127] 7) Washing: Add ethanol and deionized water and sonicate to disperse, then centrifuge, repeating twice. Disperse the washed sample in at least a small amount of anhydrous ethanol and store to obtain porous carbon-supported one-dimensional platinum-cobalt nanowires (PtCo / C NWs).

[0128] Example 8:

[0129] A porous carbon-supported one-dimensional platinum-iron nanowire (PtFe / C NWs) is prepared and its oxygen reduction application includes the following steps:

[0130] 1) Weigh 41.51 mg (0.1 mmol) potassium chloroplatinate (K2PtCl4), 35.32 mg (0.1 mmol) iron acetylacetone (Fe(acac)3) precursor and 100 mg porous carbon black, place them in an agate mortar and grind them thoroughly until they are mixed evenly to obtain precursor powder.

[0131] 2) Spread the precursor powder evenly in a quartz boat, then place it in a quartz tube and put it in a tube furnace;

[0132] 3) Introduce argon gas into the quartz tube for 20 minutes to purge the air from the quartz tube and prevent the metal from being oxidized during the heating process;

[0133] 4) Switch the gas to pure hydrogen at a flow rate of 200 ml / min; at the same time, raise the temperature of the tube furnace from room temperature to 200℃ at a heating rate of 5℃ / min and hold for 180 min.

[0134] 5) Switch the gas to a hydrogen / argon mixture (v / v = 5 / 95) at a flow rate of 200 mL / min. Simultaneously, raise the temperature of the tube furnace from 200°C to 250°C at a rate of 5°C / min, hold for 5 hours, and then allow it to cool naturally to room temperature.

[0135] 6) After the reaction is complete, switch the gas to argon, purge the residual hydrogen in the quartz tube, and take out the reduced solid powder product.

[0136] 7) Washing: Add ethanol and deionized water and sonicate to disperse, then centrifuge, repeating twice. Disperse the washed sample in at least a small amount of anhydrous ethanol and store to obtain self-assembled one-dimensional platinum-nickel alloy nanowires (Pt3Ni NWs).

[0137] Figure 1 This is a process flow diagram of the self-assembly preparation method of platinum-based nanowire electrocatalytic materials in this invention. It involves a two-part reduction method, which is simple, easy to operate, and suitable for industrial scale-up. Figure 2 Morphology and structure characterization of platinum-based alloy nanowires. Figure 2-1 TEM structure characterization of the one-dimensional platinum-nickel alloy nanowires prepared in Example 1. Figure 2-2 TEM structure characterization of the one-dimensional platinum-copper alloy nanowires prepared in Example 2. Figure 2-3 TEM structure characterization of the one-dimensional platinum-cobalt alloy nanowires prepared in Example 3. Figure 2-4 TEM structural characterization of the one-dimensional platinum-copper alloy nanowires prepared in Example 7 shows that the preparation method involved in this invention is applicable to the synthesis of various one-dimensional platinum-based binary nanowires.

[0138] Figure 3 TEM images and particle size distributions of one-dimensional PtCo alloy nanowires with different proportions prepared in Examples 3-5 are shown. The diameters of the PtCo alloy nanowires with different proportions are 3.47 nm, 5.14 nm, and 4.15 nm, respectively. This indicates that the preparation method of the present invention can be applied to the synthesis of platinum-based alloy nanowires with different proportions.

[0139] Figure 4 The images show the XRD patterns of one-dimensional PtCo alloy nanowires prepared in Examples 3-5 with different proportions, and the Co content in the nanowires prepared with different precursor ratios. XRD analysis shows that the prepared nanowires are all single-phase alloys, and the Co proportions, obtained from EDS, are 44%, 15%, and 8%, respectively. EDS results indicate that when the precursor molar ratio is Pt:Co = 1:1, the resulting nanowire molar ratio is 1.3:1, close to 1:1, indicating the best nanowire alloying effect. When the precursor molar ratio is Pt:Co = 2:1 or 3:1, the nanowires have a high Pt content and a low Co atom content, indicating that the nanowires are PtCo alloys dominated by metallic Pt.

[0140] Figure 5 In Example 7, porous carbon-supported one-dimensional platinum-cobalt nanowires and in Example 8, porous carbon-supported one-dimensional platinum-iron nanowires are respectively prepared, indicating that the preparation method of the present invention is not only applicable to self-assembled nanowires, but also applicable when a carrier is available.

[0141] Figure 6 The electrocatalytic oxygen reduction performance of platinum-cobalt nanowires with different ratios prepared in Examples 3-5 is shown. The mass activity of the Pt1Co1 nanowires is 8.6 times that of commercial platinum-carbon nanowires. Detailed data on their excellent oxygen reduction performance are shown in Table 1.

[0142] Table 1 Comparison of mass activity and specific activity of oxygen reduction electrocatalytic catalysts with different proportions of platinum-cobalt alloy nanowires

[0143]

[0144]

[0145] Figure 7 The results show the electrocatalytic oxygen reduction stability of the Pt3Ni1 nanowires prepared in Example 1. After 30,000 accelerated cycling cycles, the specific activity decreased by only 25%, and the mass activity decreased by only 30%, demonstrating excellent oxygen reduction activity and stability. Detailed data are shown in Table 2.

[0146] Table 2 Comparison of mass activity and specific activity of Pt3Ni nanowire catalysts before and after the oxygen reduction accelerated stability test (30,000 cycles).

[0147]

[0148] Figure 8 This table compares the oxygen reduction catalytic performance of the PtCo nanowires prepared in Example 3 with those prepared by reduction at only 200°C and only 300°C. The mass activity of the PtCo alloy nanowire catalyst prepared by the two-step reduction method of this invention is 5.29 times and 3.64 times that of the PtCo alloy nanowires reduced only at 200°C and 300°C, respectively. This indicates that the nanowires prepared by the two-step reduction method of this invention have excellent oxygen reduction activity. Detailed data are shown in Table 3.

[0149] Table 3 Comparison of mass activity and specific activity of Pt1Co1 by the two-step method and the one-step method.

[0150]

[0151] Figure 9 The results of testing the PtCo nanowires prepared in Example 3 and the commercial Pt / C catalyst in fuel cells are shown. The fuel cell test results indicate that the mass activity of the PtCo nanowires is 2.35 times that of the commercial Pt / C. More notably, after 30,000 accelerated life cycles, the PtCo nanowire catalyst prepared in this invention retained 63.8% of its mass activity and 80.88% of its maximum power density. In contrast, the commercial Pt / C catalyst only retained 30.0% of its original mass activity and 39.66% of its original power density. This demonstrates that the PtCo nanowires prepared in this invention maintain excellent activity and stability in fuel cell testing. Detailed data are shown in Table 4.

[0152] Table 4 Comparison of mass activity and power density of Pt1Co1 and commercial Pt / C fuel cells

[0153]

[0154] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for the self-assembly preparation of platinum-based nanowire electrocatalytic materials, characterized in that, include: 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 the platinum-based nanowire electrocatalytic material according to claim 1, characterized in that, The mixing process of the platinum precursor salt and the transition metal precursor salt also includes mixing with the support.

3. The self-assembly preparation method of the platinum-based nanowire electrocatalytic material according to claim 2, characterized in that, The carrier 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.

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