Method for preparing micro-nano platinum powder through microwave method and application of micro-nano platinum powder

Abstract

The invention discloses a microwave-assisted green micro-nano platinum powder preparation method and application thereof. The method comprises the following steps: a) preparing a platinum ion solution; b) adding a dispersing agent and a surfactant; c) adding a reducing agent; d) microwave heating reaction; e) separating and purifying a product; and f) drying: drying the product at low temperature to obtain the micro-nano platinum powder. Through microwave field enhanced mass transfer and nucleation kinetics, compared with a traditional chemical reduction method, the reaction efficiency is improved by 80% or above, high-temperature and high-pressure conditions are not needed, and the process energy consumption is reduced by about 60%. The obtained platinum nano-powder is excellent in dispersity, the specific surface area reaches 20-50 m < 2 > / g, and the platinum nano-powder shows high activity in a proton exchange membrane fuel cell catalyst. The method is suitable for continuous production, and an efficient solution is provided for application of the high-performance platinum-based material in the fields of catalysis, new energy and electronic devices.

Description

Technical Field

[0001] The present invention relates to the technical field of nano - material preparation, and particularly to a method for preparing micro - nano platinum powder by microwave method and its application. Background Art

[0002] As one of the precious metals, platinum has excellent physical and chemical properties, such as high melting point, excellent electrical conductivity, catalytic activity and corrosion resistance. Platinum nano - materials have important application values in fields such as fuel cells, electrocatalysis, sensors and electronic devices.

[0003] At present, the methods for preparing nano - platinum powder mainly include chemical reduction method, thermal decomposition method, electrochemical method, sol - gel method and micro - emulsion method, etc. However, these methods generally have problems such as harsh reaction conditions, long reaction time, high energy consumption, uneven particle size and uncontrollable morphology, which limit the industrial production and application of nano - platinum powder.

[0004] Microwave - assisted chemical synthesis technology has gradually attracted the attention of researchers due to its advantages such as uniform heating, fast reaction speed, strong selectivity and low energy consumption. However, the application of microwave technology in the preparation of micro - nano platinum powder lacks systematic research and innovation.

[0005] Therefore, developing a simple, fast and highly controllable method for preparing micro - nano platinum powder by microwave method is of great significance and is also a technical problem that the present invention urgently needs to solve. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing micro - nano platinum powder by microwave method and its application.

[0007] To solve the above - mentioned technical problems, the present invention adopts the following technical solutions:

[0008] A method for preparing micro - nano platinum powder by microwave method, comprising the following steps:

[0009] a) Prepare a platinum ion solution: Dissolve a soluble platinum salt in deionized water to obtain a platinum ion solution;

[0010] b) Add a dispersant and a surfactant: Add a dispersant and a surfactant to the platinum ion solution in step a), and stir evenly to form a clear solution;

[0011] c) Add a reducing agent: Under stirring, add a reducing agent to the solution in proportion, and continue stirring to obtain a reaction mixture;

[0012] d) Microwave - heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel and heat it;

[0013] e) Product separation and purification: After the reaction is completed, cool, centrifuge to separate the product, wash to remove impurities;

[0014] f) Drying: Dry the product at low temperature to obtain micro-nano platinum powder.

[0015] Preferably, in the step a), the soluble platinum salt is one or more of chloroplatinic acid and hexachloroplatinic acid;

[0016] The concentration range of the soluble platinum salt is 10 - 30 mmol / L;

[0017] The addition amount of the soluble platinum salt is:

[0018] Nanoscale: 0.5 - 1.0 g / 100 mL deionized water;

[0019] Micron scale: 1.0 - 2.5 g / 200 mL deionized water;

[0020] The concentration range of platinum ions is 5 - 50 mmol / L.

[0021] Preferably, in the step b), the dispersant is one or more of polyvinylpyrrolidone PVP and polyethylene glycol PEG400;

[0022] The surfactant is sodium dodecyl sulfate SDS;

[0023] The addition amount of polyvinylpyrrolidone PVP is 5 - 20 g / L;

[0024] The addition amount of polyethylene glycol PEG400 is 10 - 20 g / L;

[0025] The addition amount of sodium dodecyl sulfate SDS is 2 - 5 g / L.

[0026] Preferably, in the step c), the reducing agent is one or more of hydrazine hydrate and ethylene glycol;

[0027] The molar ratio of hydrazine hydrate to platinum ions is 5:1 - 20:1;

[0028] The concentration range of hydrazine hydrate is 0.5 - 2.0 mol / L;

[0029] The volume ratio of ethylene glycol to deionized water is 1:1 - 1:3.

[0030] Preferably, in the step d), the microwave power is 400 - 800 W, the heating time under the microwave power is 1 - 10 minutes, and the temperature of microwave heating is 60 - 100 °C.

[0031] Preferably, in the step e), the centrifugation conditions are:

[0032] Nanoscale: 8000 - 12000 rpm, 10 - 15 minutes;

[0033] Micron scale: 6000 - 8000 rpm, 5 - 10 minutes.

[0034] Preferably, in step f), the temperature for vacuum drying at low temperature is 40 - 60 °C, and the drying time is 8 - 12 hours.

[0035] Preferably, in step f), the particle size distribution of the micro - nano platinum powder is 2 - 100 nanometers.

[0036] Preferably, when the microwave power is 600 - 800 W and the dispersant is PVP, the particle size is 5 - 100 nm.

[0037] An application of a method for preparing micro - nano platinum powder by microwave method in a platinum - based catalyst, including the micro - nano platinum powder and a carrier material, can be used in fuel cells, electrocatalytic reactions and other fields that require high - performance platinum materials.

[0038] The present invention has achieved the following technical effects compared with the prior art:

[0039] (1) The present invention first applies microwave technology to the preparation of platinum powder, greatly shortening the reaction time and improving the reaction efficiency;

[0040] (2) By adjusting process parameters, the present invention realizes the controllability of the particle size of platinum powder from nano - scale to micron - scale, with uniform morphology and good dispersibility, which can meet different application requirements; and can be widely applied in fields such as catalysis, energy, electronics, etc., having important economic and social benefits;

[0041] (3) By using appropriate dispersants and reaction conditions, the present invention successfully prepares spherical - structured platinum particles with better physical and chemical properties;

[0042] (4) The reaction conditions of the present invention are mild, without high temperature and high pressure, and no harmful substances are emitted during the reaction process, meeting the concept of green chemistry;

[0043] (5) The preparation method of the present invention has simple steps, is easy to operate, is suitable for large - scale production, and has broad application prospects. Brief Description of the Drawings

[0044] Figure 1 It is a flow chart of a method for preparing micro - nano platinum powder by microwave method and its application of the present invention;

[0045] Figure 2 It is a TEM image of nano - platinum of a method for preparing micro - nano platinum powder by microwave method and its application of the present invention. Detailed Embodiments

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] The present invention discloses a method for preparing micro-nano platinum powder by a microwave method, which includes the following steps:

[0048] a) Prepare a platinum ion solution: Dissolve a soluble platinum salt with a concentration range of 10 - 30 mmol / L in deionized water to obtain a platinum ion solution;

[0049] b) Add a dispersant and a surfactant: Add a dispersant and a surfactant to the platinum ion solution in step a), stir evenly to form a clear solution;

[0050] c) Add a reducing agent: Under stirring, add a reducing agent to the solution in proportion, and continue stirring to obtain a reaction mixture;

[0051] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, with a microwave power of 400 - 800 W, a heating time of 1 - 10 minutes under the microwave power, and a microwave heating temperature of 60 - 100 °C;

[0052] e) Product separation and purification: After the reaction, cool, centrifuge to separate the product, and then wash it repeatedly 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0053] f) Drying: Vacuum dry the product at a low temperature of 40 - 60 °C for 8 - 12 hours to obtain micro-nano platinum powder.

[0054] The soluble platinum salt is one or more of chloroplatinic acid and hexachloroplatinic acid;

[0055] The addition amount of the soluble platinum salt is:

[0056] Nanoscale: 0.5 - 1.0 g / 100 mL of deionized water;

[0057] Micron scale: 1.0 - 2.5 g / 200 mL of deionized water;

[0058] The concentration range of platinum ions is 5 - 50 mmol / L.

[0059] The dispersant is one or more of polyvinylpyrrolidone PVP and polyethylene glycol PEG400;

[0060] The surfactant is sodium dodecyl sulfate SDS;

[0061] The addition amount of polyvinylpyrrolidone PVP is 5 - 20 g / L;

[0062] The addition amount of polyethylene glycol PEG400 is 10 - 20 g / L;

[0063] The addition amount of sodium dodecyl sulfate SDS is 2 - 5 g / L.

[0064] The reducing agent is one or more of hydrazine hydrate and ethylene glycol;

[0065] The molar ratio of hydrazine hydrate to platinum ions is 5:1 - 20:1;

[0066] The concentration range of hydrazine hydrate is 0.5 - 2.0 mol / L;

[0067] The volume ratio of ethylene glycol to deionized water is 1:1 - 1:3.

[0068] The centrifugation conditions are:

[0069] Nanoscale: 8000 - 12000 rpm, 10 - 15 minutes;

[0070] Micron scale: 6000 - 8000 rpm, 5 - 10 minutes.

[0071] The particle size distribution of the micro - nano platinum powder is 2 - 100 nanometers.

[0072] When the microwave power is 600 - 800 W and the dispersant is PVP, the particle size is 5 - 100 nm.

[0073] The present invention also discloses the application of a method for preparing micro - nano platinum powder by microwave method in platinum - based catalysts, including the micro - nano platinum powder and a carrier material, which can be used in fuel cells, electrocatalytic reactions and other fields that require high - performance platinum materials.

[0074] Example 1: Preparation of nano - platinum powder using hydrazine hydrate as the reducing agent

[0075] 1. Reagents and materials:

[0076] Platinum salt: Chloroplatinic acid hexahydrate, analytical pure;

[0077] Reducing agent: Hydrazine hydrate, analytical pure;

[0078] Dispersant: Polyvinylpyrrolidone (PVP, K30), analytical pure;

[0079] Solvent: Deionized water.

[0080] 2. Preparation steps:

[0081] a) Preparation of platinum ion solution: Weigh 0.5 g of chloroplatinic acid hexahydrate and dissolve it in 100 mL of deionized water to obtain a 25 mmol / L platinum ion solution;

[0082] b) Addition of dispersant: Add 1 g of PVP to the platinum ion solution in step a) and stir until completely dissolved to form a clear light yellow solution;

[0083] c) Addition of reducing agent: Slowly add 10 mL of 1 mol / L hydrazine hydrate solution under stirring. The color of the solution gradually turns dark brown, and continue stirring for 15 minutes to obtain a reaction mixture;

[0084] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600 W, the reaction time to 5 minutes, and control the temperature at 80 °C;

[0085] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it repeatedly 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0086] f) Drying: Place the product in a vacuum drying oven and dry it at 40 °C for 12 hours to obtain black nano-platinum powder.

[0087] 3. Result characterization:

[0088] Particle size analysis: Observed by transmission electron microscopy (TEM), it can be seen that the nano-platinum particles are spherical, the particle size distribution is in the range of 50 - 80 nm, and they are evenly dispersed.

[0089] Crystal structure: Tested by X-ray diffraction (XRD), the product is a face-centered cubic crystal structure of pure metallic platinum.

[0090] Specific surface area: Tested by BET, the specific surface area of the nano-platinum powder is 20 m 2 / g.

[0091] Example 2: Preparation of micron-sized platinum powder using ethylene glycol as a reducing agent

[0092] 1. Reagents and materials:

[0093] Platinum salt: Chloroplatinic acid hexahydrate, analytical grade;

[0094] Reducing agent: Ethylene glycol, analytical grade;

[0095] Dispersant: Polyethylene glycol (PEG400), analytical grade;

[0096] Surfactant: Sodium dodecyl sulfate (SDS), analytical grade;

[0097] Solvent: Deionized water.

[0098] 2. Preparation steps:

[0099] a) Prepare a platinum ion solution: Weigh 1 gram of chloroplatinic acid hexahydrate and dissolve it in 200 milliliters of deionized water to obtain a 25 mmol / L platinum ion solution;

[0100] b) Add a dispersant and a surfactant: Add 2 grams of PEG400 and 0.5 grams of SDS to the platinum ion solution in step a), and stir until completely dissolved to obtain a clear solution;

[0101] c) Add a reducing agent: While stirring, add 50 milliliters of ethylene glycol. The solution gradually turns gray, and continue stirring for 10 minutes to obtain a reaction mixture;

[0102] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 700 W, the reaction time to 8 minutes, and control the temperature at 90 °C;

[0103] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0104] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder.

[0105] 3. Result characterization:

[0106] Particle size analysis: Observed by scanning electron microscopy (SEM), it can be seen that the platinum particles are spherical, the particle size is distributed at 12 microns, and the particle size is relatively uniform.

[0107] Crystal structure: As shown by XRD testing, the product is pure metallic platinum without impurity peaks.

[0108] Example 3: Preparation of nano-sized platinum powder with low concentration of PVP

[0109] 1. Reagents and materials:

[0110] Platinum salt: Chloroplatinic acid hexahydrate, analytical grade;

[0111] Reducing agent: Hydrazine hydrate, analytical grade;

[0112] Dispersant: Polyvinylpyrrolidone (PVP, K30), analytical grade;

[0113] Solvent: Deionized water.

[0114] 2. Preparation steps:

[0115] a) Preparation of platinum ion solution: Weigh 0.8 g of chloroplatinic acid hexahydrate and dissolve it in 100 mL of deionized water to obtain a 15 mmol / L platinum ion solution;

[0116] b) Addition of dispersant: Add 0.5 g of PVP to the platinum ion solution in step a) and stir until completely dissolved to form a clear light yellow solution;

[0117] c) Addition of reducing agent: Slowly add 8 mL of 1 mol / L hydrazine hydrate solution under stirring. The color of the solution gradually turns dark brown, and continue stirring for 15 minutes to obtain a reaction mixture;

[0118] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, place it in a microwave reactor, set the microwave power to 600 W, the reaction time to 4 minutes, and control the temperature at 75 °C;

[0119] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it repeatedly 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0120] f) Drying: Place the product in a vacuum drying oven and dry it at 40 °C for 12 hours to obtain black nano-platinum powder.

[0121] 3. Result characterization:

[0122] Particle size analysis: Observed by transmission electron microscope (TEM), it can be seen that the particle size distribution is in the range of 60 - 90 nm, but some particles agglomerate.

[0123] Specific surface area: Tested by BET, the specific surface area of the nano-platinum powder is 10 m 2 / g.

[0124] This shows that the dispersibility of this example is slightly worse than that of Example 1.

[0125] Example 4: Preparation of micron-sized platinum powder from high-concentration ethylene glycol

[0126] 1. Reagents and materials:

[0127] Platinum salt: Chloroplatinic acid hexahydrate, analytical pure;

[0128] Reducing agent: Ethylene glycol, analytical pure;

[0129] Dispersant: Polyethylene glycol (PEG400), analytical pure;

[0130] Solvent: Deionized water.

[0131] 2. Preparation steps:

[0132] a) Preparation of platinum ion solution: Weigh 2 grams of chloroplatinic acid hexahydrate and dissolve it in 200 ml of deionized water to obtain a 25 mmol / L platinum ion solution;

[0133] b) Adding dispersant: Add 3 grams of PEG400 to the platinum ion solution in step a) and stir until completely dissolved to obtain a clear solution;

[0134] c) Adding reducing agent: While stirring, add 150 ml of ethylene glycol. The solution gradually turns gray, and continue stirring for 10 minutes to obtain a reaction mixture;

[0135] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 800 W, the reaction time to 10 minutes, and control the temperature at 95 °C;

[0136] e) Product separation and purification: After the reaction, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0137] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder.

[0138] 3. Result characterization:

[0139] Particle size analysis: Observed by scanning electron microscopy (SEM), it can be seen that the platinum particles are spherical particles with a particle size distribution in the range of 3 nm - 20 nm.

[0140] Example 5:

[0141] Example 3: Influence of reaction conditions on the particle size of platinum powder

[0142] 1. Experimental design:

[0143] Variable factors: Microwave power, reaction time, temperature, type and concentration of reducing agent, type and concentration of dispersant.

[0144] 2. Preparation steps:

[0145] (I) Microwave power as the variable (1)

[0147] a) Preparation of platinum ion solution: Weigh 1 gram of chloroplatinic acid hexahydrate and dissolve it in 200 ml of deionized water to obtain a 25 mmol / L platinum ion solution;

[0148] b) Adding dispersant and surfactant: Add 2 grams of PEG400 and 0.5 gram of SDS to the platinum ion solution in step a) and stir until completely dissolved to obtain a clear solution;

[0149] c) Add a reducing agent: While stirring, add 50 mL of ethylene glycol. The solution gradually turns gray. Continue stirring for 10 minutes to obtain a reaction mixture.

[0150] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel. Set the microwave power to 500 W, the reaction time to 8 minutes, and control the temperature at 90 °C.

[0151] e) Product separation and purification: After the reaction is completed, cool to room temperature. Centrifuge at 8000 rpm for 10 minutes to separate the product. Wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities.

[0152] f) Drying: Place the product in a vacuum drying oven and dry at 50 °C for 10 hours to obtain micron-sized platinum powder. (2)

[0154] a) Prepare a platinum ion solution: Weigh 1 g of chloroplatinic acid hexahydrate and dissolve it in 200 mL of deionized water to obtain a 25 mmol / L platinum ion solution.

[0155] b) Add a dispersant and a surfactant: Add 2 g of PEG400 and 0.5 g of SDS to the platinum ion solution from step a). Stir until completely dissolved to obtain a clear solution.

[0156] c) Add a reducing agent: While stirring, add 50 mL of ethylene glycol. The solution gradually turns gray. Continue stirring for 10 minutes to obtain a reaction mixture.

[0157] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel. Set the microwave power to 800 W, the reaction time to 8 minutes, and control the temperature at 90 °C.

[0158] e) Product separation and purification: After the reaction is completed, cool to room temperature. Centrifuge at 8000 rpm for 10 minutes to separate the product. Wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities.

[0159] f) Drying: Place the product in a vacuum drying oven and dry at 50 °C for 10 hours to obtain micron-sized platinum powder.

[0160] It can be seen that as the microwave power increases, the reaction rate increases and the particle size decreases, but too high a power easily leads to particle aggregation.

[0161] (II) The reaction time is the variable (1)

[0163] a) Preparation of platinum ion solution: Weigh 1 g of chloroplatinic acid hexahydrate and dissolve it in 200 mL of deionized water to obtain a 25 mmol / L platinum ion solution;

[0164] b) Addition of dispersant and surfactant: Add 2 g of PEG400 and 0.5 g of SDS to the platinum ion solution in step a), and stir until completely dissolved to obtain a clear solution;

[0165] c) Addition of reducing agent: While stirring, add 50 mL of ethylene glycol, and the solution gradually turns gray. Continue stirring for 10 minutes to obtain a reaction mixture;

[0166] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 600 W, the reaction time to 2 minutes, and control the temperature at 90 °C;

[0167] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0168] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder. (2)

[0170] a) Preparation of platinum ion solution: Weigh 1 g of chloroplatinic acid hexahydrate and dissolve it in 200 mL of deionized water to obtain a 25 mmol / L platinum ion solution;

[0171] b) Addition of dispersant and surfactant: Add 2 g of PEG400 and 0.5 g of SDS to the platinum ion solution in step a), and stir until completely dissolved to obtain a clear solution;

[0172] c) Addition of reducing agent: While stirring, add 50 mL of ethylene glycol, and the solution gradually turns gray. Continue stirring for 10 minutes to obtain a reaction mixture;

[0173] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 600 W, the reaction time to 10 minutes, and control the temperature at 90 °C;

[0174] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0175] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder.

[0176] It can be seen that for the reaction time: an extended reaction time is conducive to particle growth and an increase in particle size, while a short reaction time is beneficial for obtaining nanoparticles.

[0177] (3) The reaction temperature is a variable (1)

[0179] a) Prepare a platinum ion solution: Weigh 1 gram of chloroplatinic acid hexahydrate and dissolve it in 200 milliliters of deionized water to obtain a 25 mmol / L platinum ion solution;

[0180] b) Add a dispersant and a surfactant: Add 2 grams of PEG400 and 0.5 grams of SDS to the platinum ion solution in step a) and stir until completely dissolved to obtain a clear solution;

[0181] c) Add a reducing agent: While stirring, add 50 milliliters of ethylene glycol. The solution gradually turns gray, and continue stirring for 10 minutes to obtain a reaction mixture;

[0182] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 600 W, the reaction time to 7 minutes, and control the temperature at 65 °C;

[0183] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0184] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder. (2)

[0186] a) Prepare a platinum ion solution: Weigh 1 gram of chloroplatinic acid hexahydrate and dissolve it in 200 milliliters of deionized water to obtain a 25 mmol / L platinum ion solution;

[0187] b) Add a dispersant and a surfactant: Add 2 grams of PEG400 and 0.5 grams of SDS to the platinum ion solution in step a) and stir until completely dissolved to obtain a clear solution;

[0188] c) Add a reducing agent: While stirring, add 50 milliliters of ethylene glycol. The solution gradually turns gray, and continue stirring for 10 minutes to obtain a reaction mixture;

[0189] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 600 W, the reaction time to 7 minutes, and control the temperature at 95 °C;

[0190] e) Product separation and purification: After the reaction is completed, cool it to room temperature, centrifuge for 10 minutes at a speed of 8000 rpm to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0191] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder.

[0192] It can be seen that as the temperature increases, the reaction rate is accelerated, which is beneficial to particle growth.

[0193] (IV) The type and concentration of the reducing agent are variables (1)

[0195] a) Prepare a platinum ion solution: Weigh 1 g of hexahydrate chloroplatinic acid and dissolve it in 200 mL of deionized water to obtain a 25 mmol / L platinum ion solution;

[0196] b) Add a dispersant and a surfactant: Add 2 g of PEG400 and 0.5 g of SDS to the platinum ion solution in step a), and stir until completely dissolved to obtain a clear solution;

[0197] c) Add a reducing agent: While stirring, add 50 mL of ethylene glycol, and the solution gradually turns gray. Continue stirring for 10 minutes to obtain a reaction mixture;

[0198] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 600 W, the reaction time to 7 minutes, and control the temperature at 90 °C;

[0199] e) Product separation and purification: After the reaction is completed, cool it to room temperature, centrifuge for 10 minutes at a speed of 8000 rpm to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0200] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder. (2)

[0202] a) Prepare a platinum ion solution: Weigh 1 g of hexahydrate chloroplatinic acid and dissolve it in 200 mL of deionized water to obtain a 25 mmol / L platinum ion solution;

[0203] b) Add a dispersant and a surfactant: Add 2 g of PEG400 and 0.5 g of SDS to the platinum ion solution in step a), and stir until completely dissolved to obtain a clear solution;

[0204] c) Add a reducing agent: While stirring, slowly add 10 mL of 1 mol / L hydrazine hydrate solution, and the color of the solution gradually turns dark brown. Continue stirring for 10 minutes to obtain a reaction mixture;

[0205] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, set the microwave power to 600 W, the reaction time to 7 minutes, and control the temperature at 90 °C;

[0206] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0207] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder.

[0208] It can be seen that hydrazine hydrate is a strong reducing agent, which is beneficial to the formation of nanoparticles; ethylene glycol has a weaker reducing ability and tends to generate larger particles.

[0209] (V) The dispersant and surfactant are variables (1)

[0211] a) Prepare a platinum ion solution: Weigh 1 g of chloroplatinic acid hexahydrate and dissolve it in 200 mL of deionized water to obtain a 25 mmol / L platinum ion solution;

[0212] b) Add a dispersant and a surfactant: Add 2 g of PEG400 and 0.5 g of SDS to the platinum ion solution from step a), and stir until completely dissolved to obtain a clear solution;

[0213] c) Add a reducing agent: While stirring, add 50 mL of ethylene glycol, and the solution gradually turns gray. Continue stirring for 10 minutes to obtain a reaction mixture;

[0214] d) Microwave heating reaction: Transfer the reaction mixture from step c) to a microwave reaction vessel, set the microwave power to 700 W, the reaction time to 7 minutes, and control the temperature at 90 °C;

[0215] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, and wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0216] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder. (2)

[0218] a) Prepare a platinum ion solution: Weigh 1 g of chloroplatinic acid hexahydrate and dissolve it in 200 mL of deionized water to obtain a 25 mmol / L platinum ion solution;

[0219] b) Adding dispersant and surfactant: Add 2 g of polyvinylpyrrolidone and 0.5 g of SDS to the platinum ion solution in step a), stir until completely dissolved to obtain a clear solution;

[0220] c) Adding reducing agent: Under stirring, add 50 mL of ethylene glycol, the solution gradually turns gray, continue stirring for 10 minutes to obtain a reaction mixture;

[0221] d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel, set the microwave power to 700 W, the reaction time to 7 minutes, and control the temperature at 90 °C;

[0222] e) Product separation and purification: After the reaction is completed, cool to room temperature, centrifuge at 8000 rpm for 10 minutes to separate the product, wash it 3 times with deionized water and absolute ethanol to remove unreacted reagents and impurities;

[0223] f) Drying: Place the product in a vacuum drying oven and dry it at 50 °C for 10 hours to obtain micron-sized platinum powder.

[0224] It can be seen that the type and concentration of the dispersant affect the morphology and dispersibility of the particles; an appropriate amount of dispersant is beneficial to preventing particle aggregation.

[0225] 3. Optimization conditions:

[0226] Optimal conditions for preparing nano-sized platinum powder: microwave power 600 W, reaction time 5 minutes, temperature 80 °C, using hydrazine hydrate as the reducing agent and PVP as the dispersant.

[0227] Optimal conditions for preparing micron-sized platinum powder: microwave power 700 W, reaction time 8 minutes, temperature 90 °C, using ethylene glycol as the reducing agent and PEG400 as the dispersant.

[0228] Example 4: Application of nano-sized platinum powder in high-performance platinum-based nanomaterials

[0229] 1. Preparation of platinum-based catalyst:

[0230] a) Disperse the nano-sized platinum powder prepared in Example 1 in a mixed solution of deionized water and ethanol, and ultrasonically disperse for 30 minutes to obtain a uniform nano-sized platinum dispersion.

[0231] b) Coat the dispersion on a carrier material (such as alumina, carbon black), dry it and then heat-treat it in an inert atmosphere to prepare a platinum-based catalyst.

[0232] 2. Catalytic performance test:

[0233] Application in fuel cells:

[0234] The electrochemical performance of the obtained platinum-based catalyst was tested, and the results showed that it had high catalytic activity and stability and was suitable for proton exchange membrane fuel cells (PEMFCs).

[0235] As described above, it is only a preferred embodiment of the present invention, and it does not impose any limitation on the technical scope of the present invention. Therefore, any minor modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing micro-nano platinum powder by microwave method, characterized in that, It includes the following steps: a) Prepare a platinum ion solution: Dissolve a soluble platinum salt in deionized water to obtain a platinum ion solution; b) Add a dispersant and a surfactant: Add a dispersant and a surfactant to the platinum ion solution in step a), stir evenly to form a clear solution; c) Add a reducing agent: While stirring, add a reducing agent to the solution in proportion, and continue stirring to obtain a reaction mixture; d) Microwave heating reaction: Transfer the reaction mixture in step c) to a microwave reaction vessel and heat it; e) Product separation and purification: After the reaction ends, cool it, centrifuge to separate the product, wash it to remove impurities; f) Dry: Dry the product at a low temperature to obtain micro-nano platinum powder.

2. The method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that, In step a), the soluble platinum salt is one or more of chloroplatinic acid and hexachloroplatinic acid; The concentration range of the soluble platinum salt is 10 - 30 mmol / L; The addition amount of the soluble platinum salt is: Nanoscale: 0.5 - 1.0 g / 100 mL deionized water; Micron scale: 1.0 - 2.5 g / 200 mL deionized water; The concentration range of platinum ions is 5 - 50 mmol / L.

3. The method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that, In step b), the dispersant is one or more of polyvinylpyrrolidone PVP and polyethylene glycol PEG400; The surfactant is sodium dodecyl sulfate SDS; The addition amount of polyvinylpyrrolidone PVP is 5 - 20 g / L; The addition amount of polyethylene glycol PEG400 is 10 - 20 g / L; The addition amount of sodium dodecyl sulfate SDS is 2 - 5 g / L.

4. A method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that, In step c), the reducing agent is one or more of hydrazine hydrate and ethylene glycol; The molar ratio of hydrazine hydrate to platinum ions is 5:1 - 20:1; The concentration range of hydrazine hydrate is 0.5 - 2.0 mol / L; The volume ratio of ethylene glycol to deionized water is 1:1 - 1:

3.

5. A method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that, In step d), the microwave power is 400 - 800 W, the heating time under the microwave power is 1 - 10 minutes, and the temperature of microwave heating is 60 - 100 °C.

6. A method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that In step e), the centrifugation conditions are: Nanoscale: 8000 - 12000 rpm, 10 - 15 minutes; Micron scale: 6000 - 8000 rpm, 5 - 10 minutes.

7. A method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that, In step f), the temperature of vacuum drying at a low temperature is 40 - 60 °C, and the drying time is 8 - 12 hours.

8. A method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that, In step f), the particle size distribution of the micro-nano platinum powder is 2 - 100 nm.

9. A method for preparing micro-nano platinum powder by microwave method according to claim 1, characterized in that, When the microwave power is 600 - 800 W and the dispersant is PVP, the particle size is 5 - 100 nm.

10. Application of a method for preparing micro-nano platinum powder by microwave method in a platinum-based catalyst, characterized in that, It includes the micro-nano platinum powder and a carrier material, and can be used in fuel cells, electrocatalytic reactions and other fields that require high-performance platinum materials.

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