Ultrafine nano platinum black catalyst of three-dimensional self-supporting structure and preparation method and application thereof

Abstract

The application discloses a kind of ultrafine nano platinum black catalyst of three-dimensional self-supporting structure and its preparation method and application, it is related to catalyst technical field, including the following steps: platinum salt is dissolved in water, and first solution is obtained;Water-soluble inorganic polymerization inhibitor is added to first solution, and stirring is mixed at first temperature, and second solution is obtained;Basic solution is added to second solution, and stirring is mixed at second temperature, and third solution is obtained;Third solution is carried out drying treatment, and precursor powder is obtained;Precursor powder is placed in reducing atmosphere, and heat treatment is carried out at third temperature, and catalyst semi-finished product is obtained;The catalyst semi-finished product obtained is soaked using small molecule alcohol aqueous solution, disperses, washes, dries, and platinum black catalyst is obtained, and platinum nanowire of platinum black catalyst is interwoven, and three-dimensional network with porous structure and large specific surface area is formed.The catalyst shows excellent catalytic activity, durability and mass transfer performance.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a three-dimensional self-supporting ultrafine nano-platinum black catalyst, its preparation method, and its application. Background Technology

[0002] In recent years, fuel cell technology and electrolyzer technology have received widespread attention. However, due to the slow kinetics of the electrochemical reactions involved, catalysts must be used to improve the reaction rate. Among them, platinum-based catalysts have shown promising practical applications due to their excellent catalytic performance. Platinum black catalysts, as unsupported materials, are one of the commonly used platinum-based catalysts. Compared with other supported platinum-based catalysts (such as carbon-supported platinum catalysts), platinum black catalysts, due to the absence of a carbon support, have higher tolerance to operating temperatures, can operate at high voltages, and exhibit better stability. Therefore, platinum black catalysts are widely used in high-temperature, high-output-power applications and in scenarios where catalyst stability is extremely critical. However, due to the lack of a carrier for dispersion and anchoring, platinum black catalysts are prone to coarsening and agglomeration under actual operating conditions, leading to a decrease in catalyst efficiency. In addition, platinum black catalysts are generally composed of near-spherical nanoparticles of about a few nanometers in size. Therefore, the porosity of the catalyst layer made of platinum black catalyst is low, which leads to serious mass transfer problems. Especially in the high current density region (i.e., concentration polarization region), the oxygen mass transfer process severely restricts the output performance of the battery. These are the two major challenges faced in the development of platinum black catalysts in the industry.

[0003] In the synthesis of platinum black catalysts, platinum nanoparticles are prone to aggregation when lacking the dispersion effect of a support. To control the size of platinum particles, developers often add auxiliary agents for protection during synthesis. However, organic auxiliary agents (such as polyvinylpyrrolidone, ethylene glycol, sodium citrate, and polyether alcohols) easily coat the surface of platinum particles and are difficult to completely remove even after dissolution and washing. When the size of platinum particles is too large or there are adsorbates on the platinum surface, the number of exposed active sites on the catalyst is reduced, thus affecting the catalyst activity. Therefore, the selection of synthesis methods, raw materials, and auxiliary agents are decisive factors affecting the performance of platinum black catalysts, and the mass production of platinum black catalysts is particularly challenging.

[0004] Currently, there are few publicly available reports on the preparation methods of platinum black catalysts.

[0005] Patent document CN110124664B discloses a method for preparing metallic platinum black nanoclusters by complexing platinum salt with ammonia, adding nitrate and stirring to obtain a suspension, rotary evaporation and drying, followed by air calcination, water washing and drying, and then reduction under a mixed hydrogen atmosphere. This method includes two energy-intensive steps (high-temperature calcination and temperature reduction), further increasing the preparation cost. The first step, calcination in air to oxidize platinum to a metal oxide, followed by water washing to remove impurities, and then high-temperature heat treatment in a reducing atmosphere, may lead to sintering problems without a protective agent.

[0006] The patent document with publication number CN104416164B discloses a method for obtaining platinum black by irradiation and calcination of chloroplatinic acid. This method uses a sacrificial carbon medium to obtain platinum black with a particle size of ~10nm. The sacrificial material is g-C3N4 (graphitized carbon nitride, a calcined product of urea). The preparation and calcination removal of the carbon medium undoubtedly increases the process cost. Moreover, the uniform dispersion of platinum and carbon medium is particularly difficult to control during mass production.

[0007] Patent document CN102794171B discloses a method for preparing platinum black / platinum-ruthenium black nano-electrocatalysts, including the synthesis of a catalyst precursor-metal carbonyl cluster, magnesium oxide implantation, heat treatment of the catalyst intermediate, dissolution of magnesium oxide, and catalyst post-treatment steps. This method uses a sacrificial magnesium oxide support to obtain catalyst particle sizes between 2 nm and 20 nm; however, the acid etching process used to remove the magnesium oxide can damage the active components of the catalyst. Summary of the Invention

[0008] Given that current platinum black catalysts cannot simultaneously achieve high activity, high stability, and good mass transfer performance, and that their preparation methods are complex and difficult to mass-produce, the present invention aims to provide an ultrafine nano-platinum black catalyst with a three-dimensional self-supporting structure, its preparation method, and its application. This catalyst exhibits excellent catalytic activity, durability, and mass transfer performance. At the same time, the preparation method has a simple process flow, low production cost, and is easy to mass-produce.

[0009] This invention is achieved through the following technical solution:

[0010] In a first aspect, this application provides a method for preparing an ultrafine nano-platinum black catalyst with a three-dimensional self-supporting structure, comprising the following steps:

[0011] S1. Dissolve platinum salt in water to obtain a first solution; add a water-soluble inorganic polymerization inhibitor to the first solution and stir and mix at a first temperature to obtain a second solution; add an alkaline solution to the second solution and stir and mix at a second temperature to obtain a third solution;

[0012] S2. The third solution is dried to obtain precursor powder;

[0013] S3. Place the precursor powder in a reducing atmosphere and heat-treat it at a third temperature to obtain a catalyst semi-finished product.

[0014] S4. The catalyst semi-finished product obtained in step S3 is soaked in a small molecule alcohol aqueous solution, dispersed, washed and dried to obtain platinum black catalyst.

[0015] In the second solution of step S1, the platinum salt and inorganic polymerization inhibitor are uniformly mixed. After drying in step S2, the platinum salt and inorganic polymerization inhibitor form a completely uniform solid powder. During the high-temperature heat treatment in step S3, the inorganic polymerization inhibitor remains solid, acting as a physical barrier to protect the platinum salt and prevent problems such as pyrolysis loss, structural collapse, and sintering during the high-temperature reduction reaction. This inhibits the agglomeration and growth of platinum particles and improves the catalyst yield. Furthermore, the inorganic polymerization inhibitor is highly soluble in water, and after dissolution, it can generate a large number of pores and provide a large specific surface area, improving the mass transfer efficiency in the catalytic reaction.

[0016] In the third solution of step S1, the platinum salt is mixed with an alkaline solution. The Pt(IV) in the platinum salt gradually coordinates with the hydroxyl groups, resulting in uniform dispersion of the platinum salt in the solution. Simultaneously, an alkaline solution is added to adjust the pH, preventing corrosion of the metal components in the equipment by the acidic solution. The inorganic polymerization inhibitor, mixed with the platinum salt and alkaline solution, acts not only as a spatial confinement agent but also as a structural template and pore-forming agent, laying the foundation for the three-dimensional self-supporting structure in the synthesis of platinum black.

[0017] The purpose of heat treatment in step S3 is to reduce platinum salt to nano-platinum black. At the same time, the reduction temperature should not be higher than the melting point and decomposition temperature of the inorganic polymerization inhibitor. Using inorganic compounds as polymerization inhibitors can prevent the agglomeration of nano-platinum black and exert the steric hindrance effect.

[0018] In step S4, dispersion washing involves dispersing the catalyst semi-finished product in deionized water and performing multiple washes and solid-liquid separations until the conductivity of the washing liquid is ≤10μS / cm. The catalyst semi-finished product is uniformly dispersed in deionized water, and the dispersion method includes one or a combination of stirring and ultrasonication.

[0019] In step S4, the catalyst semi-finished product is soaked in a small molecule alcohol aqueous solution. The inorganic polymerization inhibitor is easily soluble in water, and after dissolution, it can generate a large number of pores and a large specific surface area, which can improve the mass transfer efficiency in the catalytic reaction. The small molecule alcohol is more non-polar, which is more conducive to carrying impurity ions into and out of the pores and increasing the washing and purification efficiency.

[0020] Furthermore, the platinum salt in step S1 is a water-soluble platinum-containing compound, including any one of chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinate, sodium chloroplatinate, and sodium chloroplatinate.

[0021] Furthermore, the water-soluble inorganic polymerization inhibitor in step S1 is an inorganic compound, including any one or more combinations of potassium chloride, sodium chloride, potassium bromide, and sodium bromide.

[0022] Furthermore, the alkaline solution in step S1 comprises an aqueous solution with any one of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, and potassium bicarbonate as the solute, and the concentration of the alkaline solution is 0.2 mol / L to 8 mol / L.

[0023] Furthermore, the concentration of the alkaline solution is preferably 0.5 mol / L to 5 mol / L.

[0024] Furthermore, in the first solution, the mass ratio of platinum content in the platinum salt to water is 1:(10-200).

[0025] Furthermore, in the second solution, the mass ratio of platinum content in the platinum salt to the inorganic polymerization inhibitor is 1:(5-80).

[0026] Furthermore, in the third solution, the molar ratio of alkaline solute to platinum in the alkaline solution is (1-10):(0.5-1).

[0027] Furthermore, in step S2, spray drying or freeze drying is used for drying.

[0028] The spray dryer has an inlet temperature of 150℃~180℃, an outlet temperature of 70℃~90℃, and a drying air velocity of 0.5m. 3 / min~3.5m 3 / min, spray air pressure is 120kPa~250kPa;

[0029] The freeze-drying process is divided into three stages: stage one is freezing, stage two is sublimation drying, and stage three is desorption drying. In stage one, the temperature is -60℃ to -25℃ and the holding time is 4h to 24h. In stage two, the temperature is -20℃ to -5℃ and the holding time is 4h to 24h. In stage three, the temperature is 40℃ to 85℃ and the holding time is 2h to 12h.

[0030] Spray drying ensures that the proportions of each component remain consistent in atomized drying of several small droplets, while freeze drying can quickly fix each component in the solution, including inorganic polymerization inhibitors and platinum salts, preventing them from shifting in other solid-liquid separation or drying methods. This keeps each component uniform and stable, thus avoiding catalyst particle agglomeration or uneven particle size during subsequent heat treatment.

[0031] Furthermore, the reducing atmosphere in step S3 is a mixture of a reaction gas and a balance gas; the reaction gas includes any one of hydrogen, ammonia, and carbon monoxide; the balance gas includes any one of nitrogen and argon; and the volume ratio of the reaction gas to the mixture in the reducing atmosphere is 1% to 15%.

[0032] Furthermore, the first temperature is 10℃~90℃; the second temperature is 10℃~90℃; the third temperature is 80℃~450℃; and the temperature of the small molecule alcohol aqueous solution is 50℃~90℃.

[0033] The first temperature is preferably 25℃~60℃, and the stirring time is 0.2h~3h, preferably 0.5h~1h; the second temperature is preferably 25℃~60℃, and the stirring time is 0.5h~18h, preferably 2h~6h; the third temperature is preferably 150℃~400℃, the heat treatment time is 0.5h~6h, preferably 1h~4h, and the heating rate of the heat treatment is 2℃ / min~10℃ / min.

[0034] Furthermore, the small molecule alcohol includes any one or more combinations of ethanol, n-propanol, and isopropanol; the concentration of the aqueous solution of the small molecule alcohol is 0.5 mol / L to 5 mol / L, preferably 0.8 mol / L to 2.0 mol / L.

[0035] Secondly, this application provides a three-dimensional self-supporting ultrafine nano-platinum black catalyst, which is prepared by the above-mentioned preparation method.

[0036] Furthermore, the platinum nanowires intertwine to form a three-dimensional network with a porous structure and a large specific surface area.

[0037] Thirdly, this application provides an application of the above-mentioned three-dimensional self-supporting structure of ultrafine nano-platinum black catalyst in the field of electrochemistry, including its use in the preparation of fuel cells or electrolyzers.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] (1) The platinum black catalyst prepared by the present invention has a regularly arranged three-dimensional self-supporting structure, in which platinum nanowires intertwine to form a three-dimensional network with rich pore structure and large specific surface area.

[0040] (2) The platinum black catalyst prepared by the present invention has a three-dimensional self-supporting structure, which is different from the platinum black nanoparticles and nanoclusters. The unique three-dimensional network structure enhances stability, which is conducive to accelerating charge transfer, exposing more active sites, and exhibiting excellent catalytic activity and durability.

[0041] (3) The platinum black catalyst prepared by the present invention can effectively enhance the diffusion of liquids and the transport of gases. As an electrocatalyst, it exhibits excellent mass transfer performance in the high current density region.

[0042] (4) In the preparation method of the platinum black catalyst of the present invention, an alkaline solution is added, and the Pt(IV) in the platinum salt is used to coordinate and complex with the hydroxyl group to make the platinum in the solution uniformly dispersed, which lays a good foundation for the ultrafine nanostructure of platinum black. At the same time, the alkaline solution can adjust the pH of the system to avoid the system being too acidic and causing corrosion to the metal parts in the equipment.

[0043] (5) In the preparation method of the platinum black catalyst of the present invention, the platinum salt is mixed with the inorganic polymerization inhibitor. During the high-temperature heat treatment, the inorganic polymerization inhibitor remains solid and becomes a physical barrier, which can protect the platinum salt and avoid problems such as pyrolysis loss, structural collapse and sintering of the platinum salt during the high-temperature reduction reaction. It inhibits the agglomeration and growth of platinum particles and improves the catalyst yield. In addition to the spatial confinement effect, the inorganic polymerization inhibitor also acts as a structural template agent and pore-forming agent, laying the foundation for the three-dimensional self-supporting structure in the synthesis of platinum black.

[0044] (6) The inorganic polymerization inhibitor used in this invention is readily soluble in water. After dissolution, it can generate a large number of pores and provide a large specific surface area, thereby improving the mass transfer efficiency in the catalytic reaction.

[0045] (7) The inorganic polymerization inhibitor in this invention can be removed by washing with water directly, avoiding the need to use chemical reagents to etch the non-water-soluble template agent after pyrolysis. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0047] Figure 1 Transmission electron microscopy (TEM) image of the platinum black catalyst prepared in Example 1 of this invention;

[0048] Figure 2 This is a scanning electron microscope (SEM) image of the platinum black catalyst prepared in Example 1 of the present invention.

[0049] Figure 3 This is a scanning electron microscope (SEM) image of the platinum black catalyst prepared in Comparative Example 1 of the present invention.

[0050] Figure 4 This is a scanning electron microscope (SEM) image of the platinum black catalyst prepared in Comparative Example 5 of the present invention.

[0051] Figure 5 The nitrogen physical adsorption / desorption isotherms of the platinum black catalysts prepared in Examples 1-5 of this invention are shown below.

[0052] Figure 6 The pore size distribution curves are shown for the platinum black catalysts prepared in Examples 1-5 of this invention.

[0053] Figure 7 The X-ray diffraction (XRD) patterns of the platinum black catalysts prepared in Example 1 and Comparative Examples 1, 2 and 4 of this invention are shown.

[0054] Figure 8 The X-ray diffraction (XRD) patterns of the platinum black catalysts prepared in Example 2 and Comparative Examples 6, 7 and 9 of this invention are shown.

[0055] Figure 9 The CV curves of the platinum black catalysts prepared in Example 1 and Comparative Example 1 of this invention were measured before and after the accelerated durability test.

[0056] Figure 10 The performance curves of the platinum black catalysts prepared in Example 1 and Comparative Example 1 of this invention were measured before and after fuel cell durability testing. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0058] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0059] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0060] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0061] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0062] Example 1

[0063] This embodiment provides a method for preparing a three-dimensional self-supporting structure of ultrafine nano-platinum black catalyst, wherein the mass ratio of platinum content, deionized water, and inorganic polymerization inhibitor in the platinum salt used is 1:60:15. The specific preparation method is as follows:

[0064] S1. Weigh 2.53g of chloroplatinic acid powder containing platinum, dissolve it in 152g of deionized water to obtain the first solution; add 37.90g of sodium chloride to the first solution and stir at 60℃ for 0.5h to obtain the second solution; add 55mL of 0.5mol / L sodium hydroxide solution to the second solution and continue stirring at 60℃ for 3h to obtain the third solution.

[0065] S2. The third solution obtained in step S1 is freeze-dried to obtain precursor powder.

[0066] S3. Place the precursor powder obtained in step S2 in a 10% H2 / N2 reducing atmosphere and heat-treat it at 180°C for 2 hours to obtain a catalyst semi-finished product.

[0067] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.0 mol / L ethanol aqueous solution at 80°C for 60 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain the platinum black catalyst.

[0068] The resistivity of the three-dimensional self-supporting ultrafine nano-platinum black catalyst of Example 1 was tested using the four-probe method, and the result was 0.00297 Ω·cm.

[0069] The nitrogen physical adsorption / desorption isotherms and pore size distribution curves of Example 1 are as follows: Figure 5 and 6 As shown, a significant hysteresis loop can be observed at high partial pressures in this isotherm, indicating the presence of large mesopores in the sample, which can effectively enhance gas diffusion and liquid transport, thereby improving mass transfer performance. Example 1 has a high specific surface area and pore volume of 67.93 m². 2 / g and 0.35cm 3 / g.

[0070] The morphology of the platinum black from Example 1 was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Figure 1 and 2 As can be seen, at the microscopic level, it presents a three-dimensional network composed of interwoven nanowires, with a loose porous structure, uniformly dispersed and without densely stacked regions. The diameter of the nanowires is approximately 3 nm.

[0071] Example 2

[0072] This embodiment provides a method for preparing a three-dimensional self-supporting structure of ultrafine nano-platinum black catalyst, wherein the mass ratio of platinum salt, deionized water, and inorganic polymerization inhibitor used is 1:100:30. The specific preparation method is as follows:

[0073] S1. Weigh out sodium chloroplatinate powder containing 2.53g of platinum, dissolve it in 253g of deionized water to obtain a first solution; add 75.80g of sodium chloride to the first solution and stir at 60℃ for 0.5h to obtain a second solution; add 35mL of 1.0mol / L sodium carbonate solution to the second solution and continue stirring at 60℃ for 3h to obtain a third solution.

[0074] S2. The third solution obtained in step S1 is freeze-dried to obtain precursor powder.

[0075] S3. Place the precursor powder obtained in step S2 in a 5% H2 / Ar reducing atmosphere and heat-treat it at 200°C for 2 hours to obtain a catalyst semi-finished product.

[0076] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.5 mol / L n-propanol aqueous solution at 85°C for 50 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain platinum black catalyst.

[0077] The resistivity of the three-dimensional self-supporting ultrafine nano-platinum black catalyst of Example 2 was tested using the four-probe method, and the result was 0.00352 Ω·cm.

[0078] The nitrogen physical adsorption / desorption isotherms and pore size distribution curves of Example 2 are as follows: Figure 5 and 6 As shown, a significant hysteresis loop can be observed at high partial pressures in this isotherm, indicating the presence of large mesopores in the sample, which can effectively enhance gas diffusion and liquid transport, thereby improving mass transfer performance. Example 2 has a high specific surface area and pore volume, both of which are 70.58 m². 2 / g and 0.34cm 3 / g.

[0079] Example 3

[0080] This embodiment provides a method for preparing a three-dimensional self-supporting structure of ultrafine nano-platinum black catalyst, wherein the mass ratio of platinum content, deionized water, and inorganic polymerization inhibitor in the platinum salt used is 1:60:10. The specific preparation method is as follows:

[0081] S1. Weigh out potassium chloroplatinate powder containing 2.53g of platinum, dissolve it in 152g of deionized water to obtain the first solution; add 24.85g of potassium chloride to the first solution and stir at 75℃ for 2h to obtain the second solution; add 28mL of potassium carbonate solution with a concentration of 1.0mol / L to the second solution and continue stirring at 75℃ for 4h to obtain the third solution.

[0082] S2. The third solution obtained in step S1 is spray-dried to obtain precursor powder.

[0083] S3. Place the precursor powder obtained in step S2 in a 3% H2 / Ar reducing atmosphere and heat-treat it at 150°C for 4 hours to obtain a catalyst semi-finished product.

[0084] S4. The catalyst semi-finished product obtained in step S3 is soaked in 0.8 mol / L n-propanol aqueous solution at 90°C for 50 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then freeze-dried to obtain platinum black catalyst.

[0085] The resistivity of the ultrafine nano-platinum black of the three-dimensional self-supporting structure in Example 3 was tested using the four-probe method, and the result was 0.00287 Ω·cm.

[0086] The nitrogen physical adsorption / desorption isotherms and pore size distribution curves of Example 3 are as follows: Figure 5 and 6 As shown, a significant hysteresis loop can be observed at high partial pressures in this isotherm, indicating the presence of large mesopores in the sample, which can effectively enhance gas diffusion and liquid transport, thereby improving mass transfer performance. Example 3 has a high specific surface area and pore volume, both of which are 60.08 m². 2 / g and 0.33cm 3 / g.

[0087] Example 4

[0088] This embodiment provides a method for preparing a three-dimensional self-supporting structure of ultrafine nano-platinum black catalyst, wherein the mass ratio of platinum content, deionized water, and inorganic polymerization inhibitor in the platinum salt used is 1:60:15. The specific preparation method is as follows:

[0089] S1. Weigh 8.25g of chloroplatinic acid powder containing platinum, dissolve it in 495g of deionized water to obtain the first solution; add 123.60g of sodium chloride to the first solution and stir at 85℃ for 0.5h to obtain the second solution; add 280mL of 0.5mol / L sodium hydroxide solution to the second solution and continue stirring at 25℃ for 6h to obtain the third solution.

[0090] S2. The third solution obtained in step S1 is freeze-dried to obtain precursor powder.

[0091] S3. Place the precursor powder obtained in step S2 in a 10% H2 / N2 reducing atmosphere and heat treat it at 400℃ for 3 hours to obtain a catalyst semi-finished product.

[0092] S4. The catalyst semi-finished product obtained in step S3 is soaked in 0.8 mol / L ethanol aqueous solution at 90°C for 30 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain the platinum black catalyst.

[0093] The resistivity of the ultrafine nano-platinum black in the three-dimensional self-supporting structure of Example 4 was tested using the four-probe method, and the result was 0.00322 Ω·cm.

[0094] The nitrogen physical adsorption / desorption isotherms and pore size distribution curves of Example 4 are as follows: Figure 5 and 6 As shown, a significant hysteresis loop can be observed at high partial pressures in this isotherm, indicating the presence of large mesopores in the sample, which can effectively enhance gas diffusion and liquid transport, thereby improving mass transfer performance. Example 4 has a high specific surface area and pore volume, both of which are 61.92 m². 2 / g and 0.31cm 3 / g.

[0095] Example 5

[0096] This embodiment provides a method for preparing a three-dimensional self-supporting structure of ultrafine nano-platinum black catalyst. The inorganic polymerization inhibitor uses a combination of potassium chloride and sodium chloride in a mass ratio of 1:2. The mass ratio of platinum salt, deionized water, and inorganic polymerization inhibitor used is 1:145:30. The specific preparation method is as follows:

[0097] S1. Weigh 8.25g of chloroplatinic acid powder containing platinum, dissolve it in 1200g of deionized water to obtain the first solution; add 82.80g of sodium chloride and 165.60g of potassium chloride to the first solution, and stir at 90℃ for 1h to obtain the second solution; add 80mL of 2.0mol / L sodium hydroxide solution to the second solution, and continue stirring at 90℃ for 5h to obtain the third solution.

[0098] S2. The third solution obtained in step S1 is spray-dried to obtain precursor powder.

[0099] S3. The precursor powder obtained in step S2 is placed in a 10% NH3 / N2 reducing atmosphere and heat-treated at 450°C for 6 hours to obtain a catalyst semi-finished product.

[0100] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.5 mol / L n-propanol aqueous solution at 85°C for 50 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then freeze-dried to obtain platinum black catalyst.

[0101] The resistivity of the ultrafine nano-platinum black of the three-dimensional self-supporting structure in Example 5 was tested using the four-probe method, and the result was 0.00309 Ω·cm.

[0102] The nitrogen physical adsorption / desorption isotherms and pore size distribution curves of Example 5 are as follows: Figure 5 and 6As shown, a significant hysteresis loop can be observed at high partial pressures in this isotherm, indicating the presence of large mesopores in the sample, which can effectively enhance gas diffusion and liquid transport, thereby improving mass transfer performance. Example 5 has a high specific surface area and pore volume, both of which are 63.87 m². 2 / g and 0.34cm 3 / g.

[0103] Comparative Example 1

[0104] This comparative example provides a method for preparing particulate platinum black catalysts, which differs from Example 1 in that no water-soluble inorganic polymerization inhibitor is added in this comparative example. The specific preparation method is as follows:

[0105] S1. Weigh 2.53g of chloroplatinic acid powder containing platinum and dissolve it in 152g of deionized water; add 55mL of 0.5mol / L sodium hydroxide solution and stir at 60℃ to obtain a mixture.

[0106] S2. Perform freeze-drying to obtain precursor powder.

[0107] S3. Place the precursor powder obtained in step S2 in a 10% H2 / N2 reducing atmosphere and heat-treat it at 180°C for 2 hours to obtain a catalyst semi-finished product.

[0108] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.0 mol / L ethanol aqueous solution at 80°C for 60 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain the platinum black catalyst.

[0109] The morphology of Comparative Example 1 platinum black was characterized using scanning electron microscopy (SEM). Figure 3 It can be seen that the coarse platinum particles are tightly stacked to form a disordered structure. No polymerization inhibitor was used in the preparation process, which makes the platinum black particles large in size, unevenly dispersed, and prone to agglomeration. During heat treatment, they are very easy to sinter and the structure collapses.

[0110] Comparative Example 2

[0111] This comparative example provides a method for preparing granular platinum black catalysts. The difference from Example 1 is that the amount of inorganic polymerization inhibitor added in this comparative example is relatively small, and the mass ratio of platinum content in the platinum salt, deionized water, and inorganic polymerization inhibitor is 1:60:2. The specific preparation method is as follows:

[0112] S1. Weigh 2.53g of chloroplatinic acid powder containing platinum and dissolve it in 152g of deionized water; add 5.08g of sodium chloride and stir at 60℃ for 0.5h to mix; add 55mL of 0.5mol / L sodium hydroxide solution and continue stirring at 60℃ for 3h to obtain the mixture.

[0113] S2. Perform freeze-drying to obtain precursor powder.

[0114] S3. Place the precursor powder obtained in step S2 in a 10% H2 / N2 reducing atmosphere and heat-treat it at 180°C for 2 hours to obtain a catalyst semi-finished product.

[0115] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.0 mol / L ethanol aqueous solution at 80°C for 60 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain the platinum black catalyst.

[0116] Comparative Example 3

[0117] This comparative example provides a method for preparing a platinum black catalyst. The difference from Example 1 is that in this comparative example, an excess of inorganic polymerization inhibitor is added, and the mass ratio of platinum content in the platinum salt, deionized water, and inorganic polymerization inhibitor is 1:200:90. The specific preparation method is as follows:

[0118] S1. Weigh 2.53g of chloroplatinic acid powder containing platinum and dissolve it in 506g of deionized water; add 228g of sodium chloride and stir at 60℃ for 0.5h to mix; add 55mL of 0.5mol / L sodium hydroxide solution and continue stirring at 60℃ for 3h to obtain the mixture.

[0119] S2. Perform freeze-drying to obtain precursor powder.

[0120] S3. Place the precursor powder obtained in step S2 in a 10% H2 / N2 reducing atmosphere and heat-treat it at 180°C for 2 hours to obtain a catalyst semi-finished product.

[0121] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.0 mol / L ethanol aqueous solution at 80°C for 60 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain the platinum black catalyst.

[0122] Comparative Example 4

[0123] This comparative example provides a method for preparing a platinum black catalyst, which differs from Example 1 in that an alkaline solution is not used in this comparative example. The specific preparation method is as follows:

[0124] S1. Weigh chloroplatinic acid powder containing 2.53g of platinum and dissolve it in 152g of deionized water; add 37.90g of sodium chloride and stir at 60℃ to obtain a mixture.

[0125] S2. Perform freeze-drying to obtain precursor powder.

[0126] S3. Place the precursor powder obtained in step S2 in a 10% H2 / N2 reducing atmosphere and heat-treat it at 180°C for 2 hours to obtain a catalyst semi-finished product.

[0127] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.0 mol / L ethanol aqueous solution at 80°C for 60 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain the platinum black catalyst.

[0128] Comparative Example 5

[0129] This comparative example provides a method for preparing nanocluster-shaped platinum black catalysts, using ammonia and sodium nitrate in the solution. The specific preparation method is as follows:

[0130] S1. At room temperature, weigh chloroplatinic acid powder containing 2.53g of platinum and dissolve it in 250g of deionized water; add 100mL of 10mol / L ammonia water dropwise and stir for 5h; add 100g of sodium nitrate and stir for 2h.

[0131] S2. Perform freeze-drying to obtain precursor powder.

[0132] S3. The precursor powder obtained in step S2 is first calcined in air at 400°C for 2 hours to perform platinum oxidation treatment, and then washed and dried to obtain the catalyst semi-finished product.

[0133] S4. The catalyst semi-finished product obtained in step S3 is reduced at 250°C for 2 hours in a 10% H2 / N2 reducing atmosphere to obtain a platinum black nanocluster catalyst.

[0134] The morphology of Comparative Example 5 platinum black was characterized using scanning electron microscopy (SEM). Figure 4 It can be seen that the nanoclusters of platinum black assemble into a structure with fewer pores and a slightly compact structure. This is because no polymerization inhibitor was added during the reduction of platinum using heat treatment in step S4. Therefore, the nanoclusters or nanoparticles of platinum black are prone to self-assembly, which may even lead to the risk of partial sintering.

[0135] Comparative Example 6

[0136] This comparative example provides a method for preparing a platinum black catalyst. The difference from Example 2 is that the third solution in this comparative example uses a different drying method (rotary evaporation followed by vacuum drying). The specific preparation method is as follows:

[0137] S1. Weigh out sodium chloroplatinate powder containing 2.53g of platinum, dissolve it in 253g of deionized water to obtain a first solution; add 75.80g of sodium chloride to the first solution and stir at 60℃ for 0.5h to obtain a second solution; add 35mL of 1.0mol / L sodium carbonate solution to the second solution and continue stirring at 60℃ for 3h to obtain a third solution.

[0138] S2. The third solution obtained in step S1 is subjected to rotary evaporation, then vacuum drying, and then ground to obtain precursor powder.

[0139] S3. Place the precursor powder obtained in step S2 in a 5% H2 / Ar reducing atmosphere and heat-treat it at 200°C for 2 hours to obtain a catalyst semi-finished product.

[0140] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.5 mol / L n-propanol aqueous solution at 85°C for 50 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain platinum black catalyst.

[0141] Comparative Example 7

[0142] This comparative example provides a method for preparing a platinum black catalyst. The difference from Example 2 is that in this comparative example, the platinum salt, polymerization inhibitor, and alkaline substance are not prepared into a homogeneous solution, but are directly mixed in a solid state to obtain powder. The specific preparation method is as follows:

[0143] S1. Weigh out sodium chloroplatinate powder containing 2.53g platinum, 75.80g sodium chloride, and 3.71g sodium carbonate. Grind them manually in an agate mortar for 30 minutes, and then crush them by high-speed shearing for 10 minutes to obtain a powder with uniform color.

[0144] S2. Place in a 5% H2 / Ar reducing atmosphere and heat-treat at 200℃ for 2 hours to obtain a catalyst semi-finished product.

[0145] S3. The catalyst semi-finished product obtained in step S2 is soaked in 1.5 mol / L n-propanol aqueous solution at 85°C for 50 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain platinum black catalyst.

[0146] Comparative Example 8

[0147] This comparative example provides a method for preparing a platinum black catalyst. The difference from Example 2 is that the heat treatment temperature in this comparative example is lower. The specific preparation method is as follows:

[0148] S1. Weigh out sodium chloroplatinate powder containing 2.53g of platinum and dissolve it in 253g of deionized water; add 75.80g of sodium chloride and stir at 60℃ for 0.5h to mix; add 35mL of sodium carbonate solution with a concentration of 1.0mol / L and continue stirring at 60℃ for 3h to obtain a mixture.

[0149] S2. Perform freeze-drying to obtain precursor powder.

[0150] S3. Place the precursor powder obtained in step S2 in a 5% H2 / Ar reducing atmosphere and keep it at 45°C for 2 hours to obtain a catalyst semi-finished product.

[0151] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.5 mol / L n-propanol aqueous solution at 85°C for 50 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain platinum black catalyst.

[0152] Comparative Example 9

[0153] This comparative example provides a method for preparing a platinum black catalyst. The difference from Example 2 is that the heat treatment temperature in this comparative example is too high. The specific preparation method is as follows:

[0154] S1. Weigh out sodium chloroplatinate powder containing 2.53g of platinum and dissolve it in 253g of deionized water; add 75.80g of sodium chloride and stir at 60℃ for 0.5h to mix; add 35mL of sodium carbonate solution with a concentration of 1.0mol / L and continue stirring at 60℃ for 3h to obtain a mixture.

[0155] S2. Perform freeze-drying to obtain precursor powder.

[0156] S3. Place the precursor powder obtained in step S2 in a 5% H2 / Ar reducing atmosphere and heat-treat it at 1050℃ for 2 hours to obtain a catalyst semi-finished product.

[0157] S4. The catalyst semi-finished product obtained in step S3 is soaked in 1.5 mol / L n-propanol aqueous solution at 85°C for 50 min, then dispersed and washed with deionized water until the conductivity of the washing solution is ≤10 μS / cm, and then vacuum dried at 60°C to obtain platinum black catalyst.

[0158] The catalysts prepared in the above examples and comparative examples were subjected to performance testing.

[0159] I. Characterization and Analysis of Catalyst Materials

[0160] The platinum black catalyst prepared in this invention was analyzed by X-ray diffraction (XRD), thermogravimetric analysis (TG), and nitrogen physical adsorption. The results are shown in Table 1.

[0161] The microstructure of the platinum black catalyst obtained in Example 1 was characterized using transmission electron microscopy (TEM), such as... Figure 1 As shown.

[0162] The dispersion and aggregation of the platinum black catalysts obtained in Example 1, Comparative Examples 1 and 5 were characterized using scanning electron microscopy (SEM). Figure 2-4 As shown.

[0163] II. Electrochemical Performance Testing of Catalysts

[0164] Preparation of the working electrode: 3.8 mg of the platinum black catalyst obtained in this invention was weighed and transferred to a 20 mL glass sample vial. Then, 7.6 mL of ultrapure water and 2.4 mL of isopropanol were added, and the mixture was ultrasonically dispersed for 30 min. After cooling to room temperature, 40 μL of 5% Nafion solution was added dropwise, and ultrasonication was continued for 10 min to obtain the catalyst ink. The ink was drop-coated onto a clean glassy carbon electrode, and after drying, the working electrode was obtained. The platinum loading was 15 μg / cm³. 2 In the electrochemical tests, a saturated calomel electrode was used as the reference electrode, and a graphite electrode was used as the counter electrode to build a three-electrode testing system.

[0165] Cyclic voltammetry: Electrochemical activation and cyclic voltammetry (CV) were performed in a nitrogen-saturated 0.1M HClO4 electrolyte. The scanning potential range was 0.05–1.2 V vs. RHE (relative to the reversible hydrogen electrode potential), and the scan rate was 50 mV / s. The standard CV curve was obtained, and the electrochemical active area (ECSA) was calculated. The results are shown in Table 1.

[0166] Table 1

[0167] Case Platinum particle size (nm) Platinum content (%) <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[ECSA(m 2 / g)]]> Example 1 3.50 98.45 67.93 55.94 Example 2 3.21 99.24 70.58 45.91 Example 3 4.33 99.07 60.08 44.57 Example 4 3.84 98.63 61.92 49.53 Example 5 3.81 99.63 63.87 49.19 Comparative Example 1 20.20 90.21 11.63 5.54 Comparative Example 2 12.55 92.08 16.05 9.81 Comparative Example 3 8.57 91.48 25.13 17.30 Comparative Example 4 10.95 95.58 20.44 12.77 Comparative Example 5 2.95 89.52 51.20 30.34 Comparative Example 6 9.27 94.66 23.23 15.69 Comparative Example 7 9.05 96.52 23.80 16.07 Comparative Example 8 7.25 80.56 29.71 15.82 Comparative Example 9 12.57 97.45 16.47 10.46

[0168] Accelerated durability testing: Electrochemical accelerated aging tests were performed in 0.1M HClO4 electrolyte, with a scan potential range of 0.6–0.95 V vs. RHE, a scan rate of 100 mV / s, and 30,000 CV cycles. The changes in ECSA before and after the durability test were compared (see appendix for details). Figure 9 ).

[0169] III. Fuel Cell Performance Testing

[0170] Membrane electrode preparation: The catalysts prepared in Example 1 and Comparative Example 5 were sprayed onto both sides of the polymer electrolyte membrane to prepare catalyst-coated membranes (CCMs). These CCMs were then assembled with carbon paper to form membrane electrode assemblies (MEAs) for testing. IV curves were obtained (see Appendix for details). Figure 10 Platinum usage (anode / cathode): 0.1 mg·cm⁻¹ -2 / 0.3mg·cm -2 .

[0171] Performance testing conditions: Battery operating temperature: 80℃; Relative humidity (anode / cathode): 50% / 50%; Stoichiometric ratio of reactant gases (anode / cathode): Hydrogen 1.2 / Oxygen 2.5; Back pressure (anode / cathode): 50kPa / 50kPa.

[0172] Durability cycle test conditions: temperature 75℃; humidity 100% / 100% (anode / cathode); back pressure (anode / cathode) 100 / 100kPa; flow rate (anode / cathode) 0.2 / 0.8L / min; square wave cycle: 0.6-0.95V, each lasting 3 seconds.

[0173] Table 1 compares the material characterization and performance testing of the platinum black catalysts prepared in the examples and comparative examples. Examples 1-5 all employed the method described in this invention: deionized water, platinum salt, and inorganic polymerization inhibitor were thoroughly mixed in a certain proportion, an alkaline solution was added, and the platinum was uniformly dispersed in the solution by the coordination complexation of Pt(IV) in the platinum salt with the hydroxyl groups. The precursor powder was obtained by spray drying or freeze drying, followed by heat treatment, washing, and drying to obtain an ultrafine nano-platinum black catalyst with a three-dimensional self-supporting structure composed of interwoven platinum nanowires. This highly regularly arranged nanoarray can significantly improve the conductivity of the material, thereby accelerating charge transfer. The obtained platinum black catalyst has an average particle size between 3 and 5 nm, possessing a large specific surface area and abundant pores. These characteristics are beneficial for providing more active sites and enhancing mass transport, thus exhibiting a high active surface area and demonstrating excellent catalytic activity, durability, and mass transfer performance. Figure 9 Comparing the durability tests of Example 1 and Comparative Example 1, after accelerated aging tests, the electrochemical active area of ​​Example 1 showed almost no decrease, while the ECSA of Comparative Example 1 became very small after cyclic testing. This indicates that the self-supporting structure has superior stability and electrochemical performance, while granular platinum black tends to agglomerate and grow, exhibiting poor structural stability. Figure 10The fuel cell test results presented show that Example 1 exhibits significant performance advantages in the high current density region, indicating that the three-dimensional self-supporting structure is highly beneficial for reducing mass transfer impedance. This is because the catalyst layer made with a self-supporting structure can maintain good porosity, thereby greatly mitigating the performance degradation in the high current density region caused by concentration polarization. Furthermore, the potential decay amplitude of Example 1 is smaller than that of Comparative Example 5, further demonstrating that the ultrafine nano-platinum black catalyst with a three-dimensional self-supporting structure prepared in this invention possesses excellent catalytic activity and durability.

[0174] like Figure 7 As shown, the present invention also provides comparative examples. In cases where no inorganic polymerization inhibitor was used (Comparative Example 1) and the amount of inorganic polymerization inhibitor added was too low (Comparative Example 2), there was a lack of sufficient physical barrier during high-temperature heat treatment, leading to easy sintering during the platinum salt reduction reaction, and very few pores remained in the catalyst after washing. The precursor powder in Example 1 contained an appropriate amount of inorganic polymerization inhibitor and platinum salt, and the components were uniformly dispersed, which is beneficial for improving the platinum reduction rate. However, in Comparative Examples 1 and 2, due to the lack of the barrier effect of the inorganic polymerization inhibitor, the platinum black that was reduced first may have coated part of the platinum salt, affecting the internal contact with the reducing atmosphere, thus leading to a decrease in yield; similarly, when the inorganic polymerization inhibitor was excessive (Comparative Example 3), the excessive inorganic polymerization inhibitor also coated part of the platinum salt, affecting its complete reduction, leading to a decrease in the platinum reduction rate. Comparative Example 4 did not use an alkaline solution, and the Pt(IV) of the platinum salt in the solution failed to coordinate with the hydroxyl groups, resulting in a significant increase in the average particle size of platinum. Comparative Example 5 involved reacting Pt(IV) in the platinum salt with ammonia, mixing it with sodium nitrate, calcining it in air to oxidize the platinum, and then reducing it to platinum black nanoclusters through a second heat treatment. This method resulted in fine platinum particles, but the initial oxidation followed by gas-phase thermal reduction increased energy consumption, and the reduction of platinum oxide was relatively difficult, leading to a lower platinum content in the resulting platinum black catalyst. In terms of structural stability, the morphological stability of nanoclusters is relatively weaker than that of three-dimensional self-supporting structures composed of interwoven platinum nanowires. Therefore, the ultrafine nano-platinum black catalyst with a three-dimensional self-supporting structure prepared in this invention exhibits superior durability performance in electrochemical accelerated durability testing.

[0175] like Figure 8As shown, compared with Example 2, Comparative Example 6 used rotary evaporation, and Comparative Example 7 involved directly mechanically mixing the raw material powders to prepare the solution. Both operations resulted in uneven dispersion of platinum salt and inorganic polymerization inhibitor in the precursor powder. This is because the difference in solubility between platinum salt and inorganic polymerization inhibitor leads to different rates and times of raw material precipitation during rotary evaporation, making it difficult for mechanical mixing to achieve a uniform distribution at the molecular level like in a solution. Therefore, when the components in the precursor powder are not uniform, the size and uniformity of platinum will inevitably be affected. Heat treatment conditions are crucial to the platinum reduction process. Compared with Example 2, the heat treatment temperature of Comparative Example 8 was too low, reducing the platinum reduction rate and catalyst yield; the heat treatment temperature of Comparative Example 9 was too high. At 1000°C, sodium chloride and platinum salt were in a molten state, weakening the confinement effect, and the platinum particle size increased significantly with increasing heat treatment temperature.

[0176] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for preparing an ultrafine nano-platinum black catalyst with a three-dimensional self-supporting structure, characterized in that, Includes the following steps: S1. Dissolve the platinum salt in water to obtain the first solution; A water-soluble inorganic polymerization inhibitor is added to the first solution and stirred and mixed at a first temperature to obtain a second solution; An alkaline solution is added to the second solution, and the mixture is stirred and mixed at a second temperature to obtain a third solution; The water-soluble inorganic polymerization inhibitor is an inorganic compound, including any one or more combinations of potassium chloride, sodium chloride, potassium bromide, and sodium bromide; S2. The third solution is dried to obtain precursor powder; S3. The precursor powder is placed in a reducing atmosphere and heat-treated at a third temperature to obtain a catalyst semi-finished product; the third temperature is 80℃~450℃. S4. The catalyst semi-finished product obtained in step S3 is soaked in a small molecule alcohol aqueous solution, dispersed, washed and dried to obtain a platinum black catalyst; the platinum nanowires of the platinum black catalyst are interwoven to form a three-dimensional network with a porous structure and a large specific surface area.

2. The method for preparing a three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 1, characterized in that, The platinum salt in step S1 is a water-soluble platinum-containing compound, including any one of chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinate, sodium chloroplatinate, and sodium chloroplatinate. The alkaline solution in step S1 comprises an aqueous solution with any one of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, and potassium bicarbonate as the solute, and the concentration of the alkaline solution is 0.2 mol / L to 8 mol / L.

3. The method for preparing a three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 1, characterized in that, In the first solution, the mass ratio of platinum content in the platinum salt to water is 1:(10~200); in the second solution, the mass ratio of platinum content in the platinum salt to inorganic polymerization inhibitor is 1:(5~80).

4. The method for preparing a three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 1, characterized in that, In the third solution, the molar ratio of alkaline solute to platinum in the alkaline solution is (1~10):(0.5~1).

5. The method for preparing a three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 1, characterized in that, In step S2, the drying process is carried out by spray drying or freeze drying. The spray dryer has an inlet temperature of 150℃~180℃, an outlet temperature of 70℃~90℃, and a drying air velocity of 0.5m. 3 / min~3.5m 3 / min, spray air pressure is 120kPa~250kPa; The freeze-drying process is divided into three stages: stage one is freezing, stage two is sublimation drying, and stage three is desorption drying. In stage one, the temperature is -60℃ to -25℃ and the holding time is 4h to 24h. In stage two, the temperature is -20℃ to -5℃ and the holding time is 4h to 24h. In stage three, the temperature is 40℃ to 85℃ and the holding time is 2h to 12h.

6. The method for preparing a three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 1, characterized in that, The reducing atmosphere in step S3 is a mixture of reactant gas and equilibrium gas; the reactant gas includes any one of hydrogen, ammonia, and carbon monoxide; the equilibrium gas includes any one of nitrogen and argon; the volume ratio of reactant gas to the mixture in the reducing atmosphere is 1% to 15%.

7. The method for preparing a three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 1, characterized in that, The first temperature is 10℃~90℃; the second temperature is 10℃~90℃; and the temperature of the small molecule alcohol aqueous solution is 50℃~90℃.

8. The method for preparing a three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 1, characterized in that, The small molecule alcohol includes any one or more combinations of ethanol, n-propanol, and isopropanol; the concentration of the aqueous solution of the small molecule alcohol is 0.5 mol / L to 5 mol / L.

9. A three-dimensional self-supporting structure of ultrafine nano-platinum black catalyst, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

10. The three-dimensional self-supporting ultrafine nano-platinum black catalyst according to claim 9, characterized in that, This includes materials used in the manufacture of fuel cells or electrolyzers.

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