CN113492214A

CN113492214A - Pt nano particle and preparation method thereof

Info

Publication number: CN113492214A
Application number: CN202010263465.1A
Authority: CN
Inventors: 钱晓静; 林波; 罗德礼; 杨莞; 赵雅文; 曾荣光; 赵萍; 邓潇君
Original assignee: Institute of Materials of CAEP
Current assignee: Institute of Materials of CAEP
Priority date: 2020-04-07
Filing date: 2020-04-07
Publication date: 2021-10-12
Anticipated expiration: 2040-04-07
Also published as: CN113492214B

Abstract

The invention discloses a Pt nano particle and a preparation method thereof, which solve the problems of complex operation, high cost and unfriendly environment of preparing the Pt nano particle in the prior art. The preparation method of the Pt nano particles takes ethylene glycol as a reducing agent and a protective agent, and adopts a solvothermal synthesis method to reduce chloroplatinic acid to obtain the nano-scale Pt particles. The method has the advantages of simple process, convenience in operation and low requirements on raw materials and equipment, the ethylene glycol is used for reducing chloroplatinic acid by adopting a simple solvothermal synthesis process, the nano-scale Pt particles can be obtained without a stabilizer, the size of the Pt particles is uniform and is 1-2nm, and a new thought is provided for simplifying the preparation of the nano-scale Pt particles.

Description

Pt nano particle and preparation method thereof

Technical Field

The invention relates to the technical field of nano metal, in particular to a Pt nano particle and a preparation method thereof.

Background

Due to the small size of the nano material, the nano material has many physicochemical properties which the traditional solid does not have, and mainly shows the surface effect, the volume effect, the quantum size effect, the macroscopic quantum tunneling effect and the like of the nano particles. Meanwhile, because the size of the nano-particle is small, the surface atoms of the nano-particle occupy a large proportion and have a high specific surface area, and the surface atoms generally have high activity due to insufficient coordination. In addition, the Pt nanoparticles have excellent catalytic performance and are widely applied to the fields of hydrogenation, dehydrogenation, methane conversion, photocatalysis, proton exchange membrane fuel cells and the like. In the prior art, a great deal of research is carried out on the aspects of reducing the particle size of Pt particles, improving the dispersion degree of the Pt particles and the like.

At present, Pt nanoparticles are mainly prepared by a chemical reduction method. Royangmine and the like employ hexadecyl trimethyl ammonium bromide/n-octanol/water (CTAB/C)₈H₁₇OH/H₂O) and hydrazine hydrate as a reducing agent to prepare Pt particles with the particle size of 6-8 nm at normal temperature. Plum and licorice and the like adopt a hydrothermal method, potassium chloroplatinate is taken as a precursor, polyvinylpyrrolidone (PVP) is taken as a stabilizer and a reducing agent, and petal-shaped platinum nanoparticles with uniform size and good dispersibility are synthesized in the presence of a proper amount of KBr; by adopting a solvothermal method, under the existence of a proper amount of KI, villus spherical platinum nanoparticles with uniform size and good dispersibility are synthesized by taking chloroplatinic acid as a precursor, methylamine (40%) as a reducing agent, N, N-Dimethylformamide (DMF) as a solvent and PVP as a stabilizing agent. Dissolving H in methanol and water₂PtCl₆·6H₂And O, adopting polyvinylpyrrolidone (PVP) as a stabilizer, and dropwise adding NaOH solution under vigorous stirring to prepare the Pt metal nanoparticles. Jianpeng et al, prepared nano Pt by using polyethylene glycol (PEG) with average molecular weight of 300 as a stabilizer and methanol as a reducing agent,obtaining the nano Pt catalyst with the particle size distribution of 2.5-3.0 nm.

In the preparation process of the Pt particles, besides the requirements of small particle size, high dispersion degree, uniform distribution and the like of the prepared Pt particles, the complexity of the preparation process, the preparation cost, the environmental friendliness and the like also need to be comprehensively considered. In the prior preparation method, a stabilizing agent and a reducing agent are needed to be used, sometimes a dispersing agent is needed to be introduced, and a large amount of organic matters, even some organic matters which are not environment-friendly, such as hydrazine hydrate, methylamine, formaldehyde and the like, are used. Therefore, the method for preparing the Pt nanoparticles is simple, easy and convenient to operate, and environment-friendly, and becomes a problem to be solved by the technical personnel in the field.

Disclosure of Invention

The technical problem solved by the invention is as follows: the preparation method of the Pt nanoparticles is provided, and the problems of complex operation, high cost, environmental friendliness and the like in the preparation of the Pt nanoparticles in the prior art are solved.

The invention also provides the Pt nano-particles prepared by the preparation method.

The technical scheme adopted by the invention is as follows:

the preparation method of the Pt nano particles takes ethylene glycol as a reducing agent and a protective agent, and adopts a solvothermal synthesis method to reduce chloroplatinic acid to obtain the nano-scale Pt particles.

The preparation method only adopts the ethylene glycol and the chloroplatinic acid, does not adopt other reducing agents, stabilizing agents and the like, and has the advantages of simple operation, low production cost and environmental friendliness.

In the technical scheme of the invention, the preparation method comprises the following steps: and adding a chloroplatinic acid solution into ethylene glycol, dispersing, adjusting the pH value of the mixed solution, and then heating for reaction to obtain the nano-scale Pt particles.

Specifically, the concentration of the chloroplatinic acid solution is 0.01mol/l to 0.1 mol/l.

Specifically, 0.1-10 ml of chloroplatinic acid solution is added into 8-20 ml of ethylene glycol. .

As some examples of the invention, a chloroplatinic acid solution was dispersed with ethylene glycol under ultrasonic conditions.

It should be noted that the chloroplatinic acid solution and the ethylene glycol can also be dispersed by methods known in the art, such as magnetic stirring dispersion.

Specifically, the time of ultrasonic dispersion is 15-60 min.

In the invention, the mixed solution can react only in an alkaline environment to exert the reducibility of the glycol.

In some embodiments of the present invention, the pH of the mixture is adjusted to 9-10.

The pH value of the mixed solution can be adjusted before dispersion, during the dispersion process or after the dispersion is finished. The pH is preferably adjusted during the dispersion.

As some examples of the present invention, the dispersed mixed solution with the pH adjusted is poured into a high pressure reactor, and then the high pressure reactor is placed in an oven for heating reaction.

As some embodiments of the invention, the reaction kettle is placed in an oven at 150-190 ℃ and is heated for reaction for 30-120 min.

The preparation method of the Pt nano particles comprises the following steps:

step 1, preparing a chloroplatinic acid solution: weighing a proper amount of chloroplatinic acid crystals, adding the chloroplatinic acid crystals into a proper amount of ultrapure water, stirring until the chloroplatinic acid crystals are completely dissolved, preparing a chloroplatinic acid solution with the concentration of 0.01-0.1 mol/l, and filling the chloroplatinic acid solution in a brown bottle for later use;

step 2, measuring a chloroplatinic acid solution, putting the chloroplatinic acid solution into a weighed ethylene glycol container, and putting the container containing the two liquids into an ultrasonic cleaner for ultrasonic dispersion;

step 3, gradually dripping a sodium hydroxide solution into the mixed solution subjected to ultrasonic dispersion, and adjusting the pH value of the mixed solution to 9-10;

step 4, pouring the dispersed mixed solution with the adjusted pH value into a high-pressure reaction kettle, and placing the high-pressure reaction kettle in an oven for heating reaction;

and 5, stopping the reaction, taking the reaction kettle out, and naturally cooling to room temperature.

The Pt nano-particles prepared by the preparation method are provided by the invention.

Compared with the prior art, the invention has the following beneficial effects:

(1) the method has the advantages of simple process, convenience in operation and low requirements on raw materials and equipment, the ethylene glycol is used for reducing chloroplatinic acid by adopting a simple solvothermal synthesis process, the nano-scale Pt particles can be obtained without a stabilizer, the size of the Pt particles is uniform and is 1-2nm, and a new thought is provided for simplifying the preparation of the nano-scale Pt particles.

(2) The invention has high cost performance, strong practicability, good repeatability and selectivity, has very good application prospect, and is suitable for popularization and application in the fields of catalysts, membranes, fuel cells and the like.

Drawings

FIG. 1 is a process flow diagram of the present invention.

FIG. 2-1 is a TEM image of Pt particles synthesized in example 1 of the present invention, and FIG. 2-2 is a particle size distribution diagram of Pt particles synthesized in example 1.

FIG. 3-1 is a TEM image of Pt particles synthesized in example 2 of the present invention, and FIG. 3-2 is a particle size distribution diagram of Pt particles synthesized in example 2.

FIG. 4-1 is a TEM image of Pt particles synthesized in example 3 of the present invention, and FIG. 4-2 is a particle size distribution diagram of Pt particles synthesized in example 3.

FIG. 5-1 is a TEM image of Pt particles synthesized in example 4 of the present invention, and FIG. 5-2 is a particle size distribution diagram of Pt particles synthesized in example 4.

FIG. 6-1 is a TEM image of Pt particles synthesized in example 5 of the present invention, and FIG. 6-2 is a particle size distribution diagram of Pt particles synthesized in example 5.

FIG. 7-1 is a TEM image of Pt particles synthesized in example 6 of the present invention, and FIG. 7-2 is a particle size distribution diagram of Pt particles synthesized in example 6.

FIG. 8 is a TEM image of Pt particles synthesized in example 7 of the present invention.

FIG. 9 is a TEM image of Pt particles synthesized in example 8 of the present invention.

FIG. 10 is a TEM image of Pt particles synthesized in example 9 of the present invention.

FIG. 11-1 is a TEM image of Pt particles synthesized in example 10 of the present invention, and FIG. 11-2 is a particle size distribution diagram of Pt particles synthesized in example 10.

FIG. 12-1 is a TEM image of Pt particles synthesized in example 11 of the present invention, and FIG. 12-2 is a particle size distribution diagram of Pt particles synthesized in example 11.

FIG. 13-1 is a TEM image of Pt particles synthesized in example 12 of the present invention, and FIG. 13-2 is a particle size distribution diagram of Pt particles synthesized in example 12.

Detailed Description

The present invention will be further described with reference to the following description and examples, which include but are not limited to the following examples.

As shown in attached figure 1, the invention provides a preparation method of Pt nanoparticles, which takes ethylene glycol as a reducing agent and adopts a solvothermal synthesis method to reduce chloroplatinic acid to obtain nano-scale Pt particles.

The preparation method comprises the following steps: adding a chloroplatinic acid solution into ethylene glycol, performing ultrasonic dispersion, adjusting the pH value of the mixed solution, and performing heating reaction to obtain the nano-scale Pt particles.

The concentration of the chloroplatinic acid solution is 0.01-0.1 mol/l.

Specifically, 0.01mmol of chloroplatinic acid solution is added into 8-20 ml of ethylene glycol.

The chloroplatinic acid solution was dispersed with ethylene glycol under ultrasonic conditions.

The ultrasonic dispersion time is 15-60 min.

And adjusting the pH value of the mixed solution to 9-10.

And pouring the dispersed mixed solution with the pH value adjusted into a high-pressure reaction kettle, and then placing the high-pressure reaction kettle in an oven for heating reaction.

And (3) placing the reaction kettle in an oven at the temperature of 150-190 ℃, and heating for reaction for 30-120 min.

The preparation method of the Pt nano particles comprises the following steps:

step 2, measuring a chloroplatinic acid solution, putting the chloroplatinic acid solution into a container with a measured amount of ethylene glycol, and putting the container with the two liquids into an ultrasonic cleaner for ultrasonic dispersion;

The technical effects of the present invention are illustrated in the following test cases. The test cases used chloroplatinic acid solutions with concentrations of 0.02mol/l and 0.05 mol/l. It is to be noted that the same applies to a chloroplatinic acid solution having a concentration of 0.01mol/l to 0.1 mol/l.

Example 1

The embodiment discloses a preparation method of Pt nanoparticles, which specifically comprises the following steps:

preparing a chloroplatinic acid solution: the chloroplatinic acid solution is prepared by chloroplatinic acid crystals and deionized water, 2.0g of the chloroplatinic acid crystals and 192.6ml of the deionized water are weighed to prepare the chloroplatinic acid solution with the concentration of 0.02mol/l, and the prepared chloroplatinic acid solution is contained in a brown bottle for later use.

Mixing and dispersing chloroplatinic acid and glycol solution: measuring 12ml of glycol solution, and pouring into a glass container; taking 0.5ml of chloroplatinic acid solution with the concentration of 0.02mol/l by using a liquid transfer gun, and pouring the chloroplatinic acid solution into the same glass container; placing the glass container containing the two liquids into an ultrasonic cleaner for ultrasonic dispersion for 30 min; in the ultrasonic dispersion process, 1mol/l of sodium hydroxide solution is dropwise added into the mixed solution, and the pH value of the mixed solution is adjusted to be about 10.

Solvothermal synthesis of Pt nanoparticles: pouring the ultrasonically dispersed mixed solution with the pH value adjusted into a high-pressure reaction kettle, screwing the reaction kettle, and placing the reaction kettle in a drying oven at 180 ℃ for reaction; and stopping the reaction after 30min, taking the reaction kettle out, and naturally cooling to room temperature.

Measuring 0.1ml of the synthesized liquid by using a pipette, adding 1ml of absolute ethyl alcohol, mixing, performing ultrasonic dispersion for 10min, dripping a small amount of the dispersed liquid on an ultrathin carbon film special for transmission electron microscope analysis, drying in the air, and analyzing, wherein part of analysis results are shown in fig. 2. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid solvent is 1.06 nm.

Examples 2-12 disclose methods for preparing Pt nanoparticles, which differ from example 1 in that: the concentration and the dosage of the chloroplatinic acid solution are different, the dosage of the glycol is different, and the heating temperature and the heating time are different; the other conditions were the same.

Example 2

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 14 ml; the reaction was carried out in an oven at 180 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 3. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid in the solvent is 1.31 nm.

Example 3

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 12 ml; the reaction was carried out in an oven at 170 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 4. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid in a solvent is 1.48 nm.

Example 4

The concentration of the chloroplatinic acid solution is 0.05mol/l, and the dosage is 0.2 ml; the dosage of the glycol solution is 12 ml; the reaction was carried out in an oven at 180 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 5. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid in a solvent is 1.29 nm.

Example 5

The concentration of the chloroplatinic acid solution is 0.1mol/l, and the dosage is 0.1 ml; the dosage of the glycol solution is 12 ml; the reaction was carried out in an oven at 180 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 6. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid in a solvent is 1.28 nm.

Example 6

The concentration of the chloroplatinic acid solution is 0.001mol/l, and the dosage is 10 ml; the dosage of the glycol solution is 12 ml; the reaction was carried out in an oven at 180 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 7. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid in a solvent is 1.47 nm.

Example 7

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 8 ml; the reaction was carried out in an oven at 180 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 8. Therefore, the size of the Pt nano particle thermally synthesized by reducing chloroplatinic acid with glycol is 1-2 nm.

Example 8

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 20 ml; the reaction was carried out in an oven at 180 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 9. Therefore, the size of the Pt nano particle thermally synthesized by reducing chloroplatinic acid with glycol is 1-2 nm.

Example 9

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 12 ml; the reaction was carried out in an oven at 150 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 10. Therefore, the size of the Pt nano particle thermally synthesized by reducing chloroplatinic acid with glycol is 1-2 nm.

Example 10

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 12 ml; the reaction was carried out in an oven at 190 ℃ for 30 min.

Part of the analysis results of this example are shown in fig. 11. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid in a solvent is 1.27 nm.

Example 11

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 12 ml; the reaction is carried out for 60min in an oven at 180 ℃.

Part of the analysis results of this example are shown in fig. 12. Therefore, the size of the Pt nano particle thermally synthesized by reducing chloroplatinic acid with glycol is 1-1.27 nm.

Example 12

The concentration of the chloroplatinic acid solution is 0.02mol/l, and the dosage is 0.5 ml; the dosage of the glycol solution is 12 ml; the reaction was carried out in an oven at 180 ℃ for 120 min.

Part of the analysis results of this example are shown in fig. 13. It can be seen that the average size of Pt nanoparticles thermally synthesized by using glycol to reduce chloroplatinic acid in a solvent is 1.54 nm.

According to the invention, the nano-scale Pt particles can be obtained through reactions of chloroplatinic acid solutions with different concentrations and dosages, ethylene glycol with different volumes, different temperatures and different times. The method has the advantages of simple operation, low requirements on raw materials and equipment, environmental friendliness and good repeatability and selectivity, and is particularly suitable for preparing the nano-scale noble metal catalyst.

The above-mentioned embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, and all the technical problems solved by the present invention should be consistent with the present invention, if they are not substantially modified or retouched in the spirit and concept of the present invention.

Claims

1. A preparation method of Pt nanoparticles is characterized in that ethylene glycol is used as a reducing agent and a protective agent, chloroplatinic acid is reduced by a solvothermal synthesis method, and the nano-scale Pt particles are obtained.

2. The method for preparing Pt nanoparticles according to claim 1, comprising the steps of: adding a chloroplatinic acid solution into ethylene glycol, dispersing, adjusting the pH value of the mixed solution, and then heating and reacting by using a high-pressure reaction kettle as a container to obtain the nano-scale Pt particles.

3. The method for preparing Pt nanoparticles according to claim 2, wherein the concentration of the chloroplatinic acid solution is 0.01-0.1 mol/l.

4. The method for preparing Pt nanoparticles according to claim 2 or 3, wherein 0.1-10 ml of chloroplatinic acid solution is added to 8-20 ml of ethylene glycol.

5. The method for preparing Pt nanoparticles according to claim 2 or 3, wherein the chloroplatinic acid solution is dispersed with ethylene glycol under ultrasonic conditions.

6. The method for preparing Pt nanoparticles according to claim 2 or 3, wherein the mixed solution is adjusted to be alkaline; preferably, the pH value is 9 to 10.

7. The method for preparing Pt nanoparticles according to claim 2 or 3, wherein the dispersed mixed solution with the adjusted pH value is poured into a high-pressure reaction kettle, and then the high-pressure reaction kettle is placed in an oven for heating reaction.

8. The preparation method of Pt nanoparticles according to claim 7, wherein the reaction kettle is placed in an oven at 150-190 ℃ for heating reaction for 30-120 min.

9. A preparation method of Pt nano particles is characterized by comprising the following steps:

step 4, pouring the dispersed mixed solution with the adjusted pH value into a high-pressure reaction kettle, and placing the high-pressure reaction kettle in a drying oven for heating reaction;

10. Pt nanoparticles produced by the production method according to any one of claims 1 to 9.