Platinum group metal nanocluster as well as preparation method and application thereof

Abstract

The invention provides a platinum group metal nanocluster as well as a preparation method and application thereof, and belongs to the technical field of nano materials. The preparation method comprises the steps that a platinum group metal salt phase in a water phase is transferred into a first organic solvent immiscible with water by means of a phase transfer agent, an organic phase is obtained, and the phase transfer agent is an alcohol, ammonium salt or amine compound; and adding a second organic solvent into the organic phase, and heating in an inert atmosphere, so that the platinum group metal salt in the second organic solvent is reduced through the phase transfer agent under the condition that the first organic solvent is evaporated, and the platinum group metal nanocluster is obtained. The platinum group metal nanocluster which is high in activity, small in size and good in dispersion can be prepared through a phase transfer method.

Description

Technical Field

[0001] The present disclosure relates to the technical field of nanomaterials, and in particular, to a platinum group metal nanocluster and a preparation method and application thereof. Technical Background

[0002] Precious metals mainly include metal elements such as gold, silver and platinum group metals (iridium, rhodium, platinum, palladium, ruthenium, and osmium). They have the characteristics of high melting point, high strength, and stable chemical properties. This makes precious metals, especially their nanomaterials, widely used in aerospace, pharmaceuticals, fuel cells, automotive industry and other fields.

[0003] Generally, granular materials with a particle size range of 0.1 to 100 nm are called nanomaterials. In the early stage of nanomaterial research, it was difficult to accurately separate and prepare nanomaterials of smaller sizes. However, with the development of technology, nanoclusters such as gold and silver with a particle size range of 1 to 3 nm have gradually been prepared. Compared with conventional nanomaterials, gold and silver nanoclusters have higher specific surface areas and more active sites, and show good catalytic activity in catalytic reactions, with great development prospects and more application advantages.

[0004] However, due to the very small size of nanoclusters, the preparation of nanoclusters faces more challenges than conventional nanomaterials. Gold and silver are metals that have been widely studied. Nanoclusters can be synthesized by phase transfer method. Specifically, low-cost inorganic salt precursors can be selected as raw materials, and reduction reactions can be carried out in the organic phase through phase transfer, which is conducive to the preparation of metal nanoparticles with smaller particle size.

[0005] However, the above methods still have the following problems: the phase transfer efficiency of transferring inorganic salt precursors to organic phase is low, and additional reducing agents need to be added after the transfer to reduce the precious metal particles, which increases the preparation cost. Compared with gold and silver, platinum group metals are less active, which further increases the difficulty of synthesizing their nanoclusters. It is urgent to find an effective method for synthesizing platinum group metal nanoclusters. Summary of the invention

[0006] In view of this, the main purpose of the present disclosure is to provide a platinum group metal nanocluster and a preparation method and application thereof, in order to at least partially solve at least one of the above-mentioned technical problems.

[0007] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0008] According to an embodiment of one aspect of the present disclosure, a method for preparing platinum group metal nanoclusters is provided, comprising: using a phase transfer agent to transfer a platinum group metal salt in an aqueous phase to a first organic solvent that is immiscible with water to obtain an organic phase, wherein the phase transfer agent is an alcohol, an ammonium salt or an amine compound; adding a second organic solvent to the organic phase, and heating it under an inert atmosphere, so that when the first organic solvent is evaporated, the platinum group metal salt in the second organic solvent is reduced by the phase transfer agent to obtain platinum group metal nanoclusters.

[0009] According to another embodiment of the present disclosure, there is provided a platinum group metal nanocluster prepared by the above method.

[0010] According to another embodiment of the present disclosure, there is provided an application of the above-mentioned platinum group metal nanoclusters as catalysts in the fields of fuel cells, water electrolysis, catalytic hydrogenation, corrosion-resistant coatings, chiral medicines, and pesticides.

[0011] According to the embodiments of the present disclosure, in the process of preparing platinum group metal nanoclusters, alcohols, ammonium salts or amine compounds are selected as phase transfer agents. On the one hand, they can complex with platinum group metal ions in the aqueous phase and transfer the platinum group metal ions in the aqueous phase to the organic phase by utilizing their own affinity for organic solvents; on the other hand, by utilizing their reducing properties, the platinum group metal ions can be reduced by thermal reduction in the organic phase without the need to add additional reducing agents, thereby preparing highly active, small-sized and well-dispersed platinum group metal nanoclusters. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a flowchart of a method for preparing platinum group metal nanoclusters in an embodiment of the present disclosure;

[0013] Figure 2 This is a flow chart of the preparation method of iridium nanoclusters in Example 1 of the present disclosure;

[0014] Figure 3 This is a transmission electron microscope image of the iridium nanoclusters in Example 1 of the present disclosure;

[0015] Figure 4 is a particle size distribution diagram of iridium nanoclusters in Example 1 of the present disclosure;

[0016] Figure 5 is a transmission electron microscope image of the iridium nanoclusters in Example 5 of the present disclosure;

[0017] Figure 6 is a particle size distribution diagram of rhodium nanoclusters in Example 6 of the present disclosure;

[0018] Figure 7 is a particle size distribution diagram of ruthenium nanoclusters in Example 7 of the present disclosure;

[0019] Figure 8 is a transmission electron microscope image of iridium nanoparticles in comparative example 1 of the present disclosure;

[0020] Fig. 9 is a transmission electron microscope image of iridium nanoparticles in comparative example 2 of the present disclosure;

[0021] Fig.10 This is a transmission electron microscope image of the iridium nanoparticles in Comparative Example 3 of the present disclosure. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0023] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components. All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0024] For nanomaterials of platinum group metals such as iridium, common preparation systems include aqueous phase and organic phase. In the aqueous phase, inorganic salts of platinum group metals can be dissolved in water, and then reduced to nanoparticles using water-soluble reducing agents such as sodium borohydride, citric acid, sodium citrate, etc.; or, in the organic phase, organic precursors of platinum group metals such as iridium acetylacetonate are dispersed in an organic medium, and then reduced at high temperature to generate nanoparticles. Through research, it was found that the two preparation systems have the following characteristics:

[0025] In the aqueous phase, low-cost inorganic salts are used as precursors, the reaction is simple and easy to prepare, but due to the strong polarity of water, the prepared nanoparticles are prone to agglomeration, the particle size is too large, and the catalytic performance is uncontrollable; while the nanoparticles prepared in the organic phase are evenly dispersed, the particles are small, the morphology is controllable, and they are easy to separate from the reaction system. The catalytic activity is high, but the price of organic precursors is high and the reaction conditions are harsh. Therefore, a phase transfer method combining the two is proposed to prepare platinum group metal nanoparticles.

[0026] However, reports on the synthesis of metal nanoclusters by phase transfer method mainly focus on relatively active gold and silver noble metal species, and there are problems such as low phase transfer efficiency and the need to add additional reducing agents to reduce noble metal particles. In the process of realizing the present disclosure, it was found that after the platinum group metal salt was transferred to the organic phase using a reducing alcohol, ammonium salt or amine phase transfer agent, the platinum group metal salt can be directly thermally reduced using the above phase transfer agent in a suitable organic solvent system without the need to add additional reducing agents, and highly active, small-sized and highly dispersed platinum group metal nanoclusters can be prepared.

[0027] Specifically, according to some embodiments of the present disclosure, a method for preparing platinum group metal nanoclusters is provided. Figure 1 is a flowchart of the method for preparing platinum group metal nanoclusters in the embodiment of the present disclosure, such as Figure 1 As shown, the preparation method disclosed herein includes the following steps S101 to S102.

[0028] In step S101, a phase transfer agent is used to transfer the platinum group metal salt in the aqueous phase to a first organic solvent that is immiscible with water to obtain an organic phase, wherein the phase transfer agent is an alcohol, an ammonium salt or an amine compound;

[0029] In step S102, a second organic solvent is added to the organic phase, and the organic phase is heated under an inert atmosphere, so that when the first organic solvent is evaporated, the platinum group metal salt in the second organic solvent is reduced by a phase transfer agent to obtain platinum group metal nanoclusters.

[0030] According to the embodiments of the present disclosure, alcohols, ammonium salts or amine compounds are selected as phase transfer agents. On the one hand, they can be complexed with platinum group metal ions in the aqueous phase and transfer the platinum group metal ions in the aqueous phase to the organic phase by utilizing their own affinity for organic solvents; on the other hand, by utilizing their own reducing properties, platinum group metal ions can be reduced in the organic phase by thermal reduction without the need to add additional reducing agents, thereby preparing highly active, small-sized and well-dispersed platinum group metal nanoclusters. In addition, since platinum group metal salts soluble in the aqueous phase can be used, it has the advantage of lower cost.

[0031] It should be noted that, in the present disclosure, the term "nanocluster" refers to nanomaterials with a particle size range of 1 to 3 nm; and "platinum group metal nanocluster" refers to a nanocluster structure formed by the mutual bonding of dozens to hundreds of platinum group metal atoms.

[0032] In the present disclosure, the meaning of "immiscible with water" in the above-mentioned term "first organic solvent immiscible with water" includes the situations of being not easily soluble in water, poorly soluble in water and insoluble in water, and separation from the water phase can be achieved based on this immiscible property with water.

[0033] In the present disclosure, the term "inert atmosphere" includes any one or more combinations of inert gases such as nitrogen, argon or helium to reduce the adverse effects of gases such as oxygen on the reduction reaction.

[0034] In the present disclosure, the above-mentioned term "platinum group metals" is also called "platinum group elements", which mainly include six metal elements: platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), osmium (Os), and iridium (Ir).

[0035] According to an embodiment of the present disclosure, in step S101, the platinum group metal salt may be a chloro complex of iridium, rhodium, platinum, palladium, ruthenium or osmium. The chloro complex of the platinum group metal can be fully dissolved in water as a precursor, and then a subsequent phase transfer operation is performed. Taking iridium as an example, the iridium salt may be selected from chloroiridic acid (H 2 IrCl 6 6H 2 O), potassium chloroiridate (K 2 IrCl 6 ), sodium chloroiridate (Na 2 IrCl 6 ), preferably chloroiridic acid and potassium chloroiridate.

[0036] According to an embodiment of the present disclosure, further, in order to reduce the influence of impurities in water on subsequent phase transfer, deionized water or ultrapure water can be selected to dissolve the platinum group metal salt to obtain an aqueous phase.

[0037] According to the embodiments of the present disclosure, in step S101, the concentration of the platinum group metal salt in the aqueous phase has a great influence on the phase transfer efficiency. If the concentration is too low, the yield of the platinum group metal nanoclusters will be low; if the concentration is too high, some platinum group metal ions will be difficult to transfer to the aqueous phase, resulting in the loss of platinum group metal ions. Therefore, in the aqueous phase, the concentration of the platinum group metal salt is generally 0.2 to 10 g / L, preferably 1 to 5 g / L, for example, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, etc.

[0038] According to an embodiment of the present disclosure, in step S101, the phase transfer agent can be complexed with the platinum group metal ions in the aqueous phase, and utilize its affinity for the first organic solvent to transfer the platinum group metal salt in the aqueous phase to the first organic solvent; at the same time, the phase transfer agent must also have reducing properties. Therefore, the optional phase transfer agent can be an alcohol, an ammonium salt or an amine compound, for example, it can be at least one of polyethylene glycol, ethylene glycol, octadecyl mercaptan, dodecyl mercaptan, tetrabutylammonium bromide, trioctylammonium chloride, hexadecyltrimethylammonium bromide, tributylammonium, dodecylamine, and octadecylamine, preferably tetrabutylammonium bromide and dodecylamine.

[0039] According to an embodiment of the present disclosure, in step S101, the first organic solvent needs to have good miscibility with the phase transfer agent, and can be a halogenated or non-halogenated C6-C12 alkane, C6-C10 aromatic hydrocarbon, or C2-C10 alkyl ether solvent.

[0040] In the present disclosure, the above-mentioned term "C6-C10 alkane solvent" includes alkanes and cycloalkanes, for example, hexane, cyclohexane, n-heptane, cycloheptane, n-octane, n-decane, etc., wherein the hexane may be n-hexane and / or isohexane. Correspondingly, the meaning of "halogenated C6-C12 alkanes" is that the aforementioned solvent has a halogen substituent such as fluorine, chlorine, bromine, iodine, etc. The above-mentioned term "C6-C10 aromatic hydrocarbon solvent" may be, for example, toluene, ethylbenzene, etc. The above-mentioned term "C2-C10 alkyl ether solvent" may be, for example, diethyl ether, dipropyl ether, diisopropyl ether, ethyl butyl ether, etc.

[0041] According to an embodiment of the present disclosure, the first organic solvent may be at least one of hexane, cyclohexane, toluene, chloroform, and ether. The first organic solvent may be insoluble in water and have good miscibility with alcohols, ammonium salts, or amine phase transfer agents.

[0042] According to an embodiment of the present disclosure, in order to improve the phase transfer efficiency, step S101 may specifically include: adding an amphoteric solvent containing a phase transfer agent to an aqueous solution of a platinum group metal salt, then adding a first organic solvent for stirring, and standing to separate the layers after stirring to obtain an organic phase containing a platinum group metal salt.

[0043] The term "amphoteric solvent" refers to an organic solvent that is miscible with water, and at the same time, the amphiphilic solvent is also miscible with the phase transfer agent. By selecting an amphiphilic solvent to dissolve the phase transfer agent, the phase transfer agent can be more easily incorporated into the first organic solvent after complexing with the platinum group metal ions in the water phase, thereby improving the phase transfer efficiency.

[0044] According to the embodiments of the present disclosure, the addition of an amphoteric solvent is not necessary, but the phase transfer efficiency is lower than that of the case where an amphoteric solvent is added. That is, in step S101, the phase transfer agent can be directly added to the aqueous solution of the platinum group metal salt, and the first organic solvent is added and stirred, and the mixture is allowed to stand for stratification after stirring to obtain an organic phase containing the platinum group metal salt.

[0045] According to an embodiment of the present disclosure, further, the amphoteric solvent can be at least one of alcohols, amides, and ether solvents, preferably selected from at least one of ethanol, methanol, isopropanol, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, and tetrahydrofuran. The above amphoteric solvent is selected to be soluble in water and miscible with the phase transfer agent.

[0046] According to the embodiments of the present disclosure, further, the volume ratio of the phase transfer agent to the amphoteric solvent determines the efficiency of the phase transfer. Too high or too low is not conducive to improving the phase transfer efficiency. Generally, the volume ratio is 1:10 to 1:100, preferably 1:10 to 1:30, for example, it can be 1:10, 1:15, 1:20, 1:25, 1:30, etc.

[0047] Furthermore, the volume ratio of the phase transfer agent to the aqueous phase can be 1:10 to 1:100, preferably 1:10 to 1:30, for example, 1:10, 1:15, 1:20, 1:25, 1:30, etc. The volume ratio of the phase transfer agent to the aqueous phase affects the phase transfer efficiency and also affects the amount that can enter the organic phase as a reducing agent.

[0048] According to the embodiments of the present disclosure, further, stirring time and standing time also affect the phase transfer efficiency. The stirring time can be 0 to 100 min, for example, 20 min, 30 min, 40 min, 60 min, 80 min, 100 min, etc., and the standing time can be 0 to 30 min, for example, 10 min, 20 min, 30 min, etc.

[0049] According to the embodiments of the present disclosure, in order to overcome the problems of low phase transfer efficiency and low concentration of platinum group metal ions in the organic phase, the present disclosure further proposes the use of multiple phase transfer and organic phase concentration operations, thereby improving the efficiency of phase transfer and increasing the yield of platinum group metal nanoclusters.

[0050] Specifically, after step S101 and before step S102, the preparation method of the present disclosure further includes: repeating the phase transfer operation in step S101, combining the organic phases obtained by multiple phase transfers, and concentrating them to obtain a concentrated organic phase.

[0051] According to an embodiment of the present disclosure, in order to improve the efficiency of phase transfer and increase the concentration of platinum group metal ions in the first organic solvent, the number of phase transfer operations may be 1 to 10 times, preferably 1 to 5 times.

[0052] According to an embodiment of the present disclosure, in order to accelerate the concentration of the organic solvent and avoid the aggregation of platinum group metal ions in the first organic solvent, the concentration operation may include: evaporating the combined organic phase by stirring or rotary evaporation at normal pressure or negative pressure and a temperature of 0 to 100°C.

[0053] For example, the evaporation of the first organic solvent can be accelerated by heating and magnetic stirring under normal pressure or negative pressure, and the heating temperature and stirring speed are strictly controlled. The heating temperature can be 20-100°C, for example, 20°C, 40°C, 60°C, 80°C, 100°C, and the stirring speed is 0-2000rpm / min, for example, 500rpm / min, 1000rpm / min, 1500rpm / min, 2000rpm / min, etc.

[0054] For another example, the evaporation of the first organic solvent can be accelerated and the concentration of the platinum group metal ions can be increased by heating and rotary evaporation under negative pressure. The heating temperature can be 20-100°C, for example, 20°C, 40°C, 60°C, 80°C, 100°C, etc., and the rotation speed can be 20-180rpm / min, for example, 20rpm / min, 80rpm / min, 120rpm / min, 180rpm / min, etc.

[0055] According to the embodiments of the present disclosure, the volume of the first organic solvent has a direct impact on the concentration operation, which is manifested as follows: when only one phase transfer operation is performed, using a suitable volume of the first organic solvent, the organic phase may not be concentrated, and the second organic solvent may be directly added to the organic phase; in the process of performing multiple phase transfer operations, using a suitable volume of the first organic solvent can reduce the concentration time and simplify the operation when the combined organic phase is concentrated. Therefore, in one phase transfer operation, the volume ratio of the first organic solvent to the aqueous phase is 2 / 1-1 / 3, for example, it can be 2 / 1, 1 / 1, 1 / 2, 1 / 3, etc.

[0056] According to the embodiments of the present disclosure, the concentration of the concentrated platinum group metal salt is generally 10-15 g / L, and a suitable volume of organic solution is beneficial to increasing the concentration of platinum group metal ions, thereby increasing the yield of platinum group metal nanoclusters.

[0057] According to an embodiment of the present disclosure, in step S102, a second organic solvent is added and then heated to evaporate the first organic solvent, thereby allowing the thermal reduction reaction to be carried out in a suitable solvent without causing aggregation of platinum group metal ions.

[0058] According to an embodiment of the present disclosure, step S102 specifically includes: heating the organic phase containing the second organic solvent in a staged heating method under an inert atmosphere; wherein the first organic solvent is evaporated in a first heating stage, and the platinum group metal salt in the second organic solvent is reduced using a phase transfer agent in a second heating stage.

[0059] According to an embodiment of the present disclosure, a staged temperature increase strategy is adopted to synthesize highly dispersed platinum group metal nanoclusters. Impurities including water and the first organic solvent can be removed at a relatively low temperature, and then the platinum group metal salt in the second organic solvent is thermally reduced at a relatively high temperature to prepare platinum group metal nanoclusters.

[0060] According to an embodiment of the present disclosure, further, the final temperature of the first heating stage can be 50-200°C, for example, 50°C, 100°C, 150°C, 200°C, etc., and the final temperature of the second heating stage can be, for example, 180-300°C, for example, 180°C, 200°C, 250°C, 300°C, etc.

[0061] The above temperature in the first heating stage ensures that platinum group metal ions cannot be reduced and can reach the boiling point of water, impurities and organic solvents. The above temperature in the second heating stage ensures that platinum group metal ions can be reduced without wasting energy due to the high temperature.

[0062] According to an embodiment of the present disclosure, the second organic solvent has a C10-C20 long-chain hydrocarbon group, is suitable for inhibiting the agglomeration of platinum group metal nanoclusters, and is preferably selected from at least one of octadecene, lecithin, and oleic acid. The second organic solvent can be adsorbed onto the surface of the platinum group metal nanoclusters, and the C10-C20 long-chain hydrocarbon group can inhibit the agglomeration of the platinum group metal nanoclusters during thermal reduction, which has an important influence on the morphology shaping and dispersibility of the platinum group metal nanoclusters.

[0063] According to an embodiment of the present disclosure, the volume ratio of the second organic solvent to the phase transfer agent is 3 / 1 to 8 / 1, for example, 3 / 1, 4 / 1, 5 / 1, 6 / 1, 7 / 1, 8 / 1, etc. The appropriate amount of the second organic solvent is conducive to the reduction reaction at a suitable concentration, thereby increasing the yield of platinum group metal nanoclusters.

[0064] According to an embodiment of the present disclosure, after step S102, step S103 is further included, in which, after the reduction reaction is completed, a washing solvent and a precipitant are added to the second organic solvent containing the platinum group metal nanoclusters, and ultrasonic vibration is performed to separate and obtain dispersed platinum group metal nanoclusters.

[0065] According to an embodiment of the present disclosure, in step S103, the washing solvent is used to remove the residual solvent on the surface of the platinum group metal nanoparticles, and can be selected from hexane, acetone, cyclohexane or n-pentane; the precipitant is used to precipitate the platinum group metal nanoparticles for subsequent separation, such as centrifugal separation, and can be selected from methanol, ethanol, isopropanol.

[0066] According to an embodiment of the present disclosure, further, the speed of the centrifuge in centrifugal separation can be 0-13000 rpm / min, for example, it can be 5000 rpm / min, 8000 rpm / min, 10000 rpm / min, 13000 rpm / min, etc.

[0067] According to some embodiments of the present disclosure, there is also provided a platinum group metal nanocluster prepared by using the above-mentioned method for preparing the platinum group metal nanocluster.

[0068] According to the embodiments of the present disclosure, the prepared platinum group metal nanoclusters have a particle size range of 1 to 3 nm and have high dispersibility and activity.

[0069] According to some embodiments of the present disclosure, there is also provided an application of the above-mentioned platinum group metal nanoclusters as catalysts in the fields of fuel cells, water electrolysis, catalytic hydrogenation, corrosion-resistant coatings, chiral medicines, and pesticides.

[0070] The present invention is further described below by embodiments and related test experiments. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments may also be implemented without these specific details. And, in the absence of conflict, the details in the following embodiments may be combined into other feasible embodiments at will.

[0071] Example 1

[0072] Figure 2 is a flow chart of the preparation method of iridium nanoclusters in Example 1 of the present disclosure, such as Figure 2 As shown, the preparation method of iridium nanoclusters in this embodiment includes:

[0073] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0074] (2) Phase transfer: Add 3 mL of dodecylamine to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing dodecylamine to the deionized water containing iridium ions, and add 50 mL of n-hexane solution at the same time. Stir vigorously for 30 min and let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Then, repeat the above phase transfer operation to prepare the n-hexane solution containing iridium ions three times, then gather these n-hexane solutions together, stir at 1500 rpm / min, raise the temperature to 80°C and heat for 5 h to concentrate. After concentration, the volume of the organic phase is 5 mL.

[0075] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 230°C and maintain it for 2 hours.

[0076] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing the iridium nanoclusters, ultrasonically shaken for 30 min, and then centrifuged at a speed of 10,000 rpm / min. Finally, the iridium nanoclusters obtained by centrifugation are redispersed in the n-hexane solution for preservation.

[0077] For the aqueous solution after the first phase transfer in step (2), inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to measure the concentration of iridium ions before and after the transfer. The results are shown in Table 1. It can be seen that the transfer efficiency of iridium ions reached 99.85%.

[0078] Table 1. Iridium ion phase transfer efficiency

[0079]

[0080] Figure 3 is a transmission electron microscope image of the iridium nanoclusters in Example 1 of the present disclosure, such as Figure 3 As shown in the figure, it can be seen that the synthesized iridium nanoclusters have good dispersion and uniform particle size. The particle sizes of more than 100 iridium nanoparticles in the transmission electron microscope are obtained. Figure 4 , Figure 4 is a particle size distribution diagram of the iridium nanoclusters in Example 1 of the present disclosure, such as Figure 4 As shown, the average particle size of the synthesized iridium nanoclusters is 1.7 nm, which is relatively small.

[0081] Example 2

[0082] The preparation method of iridium nanoclusters in this embodiment includes:

[0083] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0084] (2) Phase transfer: Add 2 mL of dodecylamine to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing dodecylamine to the deionized water containing iridium ions, and add 50 mL of n-hexane solution at the same time. Stir vigorously for 30 min and let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Repeat the above phase transfer operation 3 times to prepare n-hexane solutions containing iridium ions multiple times, then gather these n-hexane solutions together, stir at 1500 rpm / min, raise the temperature to 80°C and heat for 5 h to concentrate. After concentration, the volume of the organic phase is 5 mL.

[0085] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 230°C and maintain it for 2 hours.

[0086] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing the iridium nanoclusters, ultrasonically shaken for 30 min, and then centrifuged at a speed of 10,000 rpm / min. Finally, the iridium nanoclusters obtained by centrifugation are redispersed in the n-hexane solution for preservation.

[0087] For the aqueous solution after the first phase transfer in step (2), inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to measure the concentration of iridium ions before and after the transfer. The results are shown in Table 2. Compared with Table 1, it can be seen that as the phase transfer dose decreases, the phase transfer efficiency also decreases.

[0088] Table 2. Iridium ion phase transfer efficiency

[0089]

[0090] Example 3

[0091] The preparation method of iridium nanoclusters in this embodiment includes:

[0092] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0093] (2) Phase transfer: Add 5 mL of dodecylamine to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing dodecylamine to the deionized water containing iridium ions, and add 50 mL of n-hexane solution at the same time. Stir vigorously for 30 min and let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Then, repeat the above phase transfer operation three times, then gather these n-hexane solutions together, stir at 1500 rpm / min, increase the temperature to 80°C and heat for 5 h to concentrate. After concentration, the volume of the organic phase is 5 mL.

[0094] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 230°C and maintain it for 2 hours.

[0095] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing the iridium nanoclusters, and ultrasonic vibration is performed for 30 minutes, followed by centrifugation at a speed of 10,000 rpm / min. Finally, the iridium nanoclusters obtained by centrifugation are redispersed in a n-hexane solution for preservation.

[0096] From Table 3, we can see that when the amount of phase transfer agent increases, the transfer efficiency decreases, which means that simply increasing the amount of phase transfer agent has little effect on improving the efficiency.

[0097] Table 3. Iridium ion phase transfer efficiency

[0098]

[0099] Example 4

[0100] The preparation method of iridium nanoclusters in this embodiment includes:

[0101] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0102] (2) Phase transfer: Add 3 mL of tetrabutylammonium bromide to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing tetrabutylammonium bromide to the deionized water containing iridium ions, and add 50 mL of n-hexane solution at the same time. Stir vigorously for 30 min and let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Repeat the above phase transfer operation to prepare the n-hexane solution containing iridium ions three times, then gather these n-hexane solutions together, stir at 1500 rpm / min, increase the temperature to 80°C and heat for 5 h to concentrate. The volume of the organic phase after concentration is 5 mL.

[0103] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 230°C and maintain it for 2 hours.

[0104] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing the iridium nanoclusters, ultrasonically shaken for 30 min, and then centrifuged at a speed of 10,000 rpm / min. Finally, the iridium nanoclusters obtained by centrifugation are redispersed in a n-hexane solution for preservation.

[0105] It can be seen from Table 4 that the phase transfer efficiency is 99.62% when tetrabutylammonium bromide is used as the phase transfer agent, which is slightly lower than that of dodecylamine.

[0106] Table 4. Iridium ion phase transfer efficiency

[0107]

[0108] Example 5

[0109] The preparation method of iridium nanoclusters in this embodiment includes:

[0110] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0111] (2) Phase transfer: Add 3 mL of dodecylamine to 50 mL of ethanol and stir for 10 min to fully dissolve it. Then add the ethanol solution containing dodecylamine to the deionized water containing iridium ions and add 50 mL of n-hexane solution. Stir vigorously for 30 min and let it stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, then aspirate the upper liquid into a beaker.

[0112] (3) Thermal reduction: Place the n-hexane solution containing iridium ions in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 230°C and maintain it for 2 hours.

[0113] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing iridium nanoclusters, ultrasonically shaken for 30 minutes, and then centrifuged at a speed of 10,000 rpm / min. Finally, the iridium nanoclusters obtained by centrifugation are redispersed in the n-hexane solution, and then 20 mg of activated carbon is added for loading.

[0114] Since the present embodiment does not carry out the concentration step, the prepared iridium nanoclusters are less and the concentration is lower, so activated carbon is used for loading, and the transmission electron microscope image thereof is as follows: Figure 5 As shown, it can be seen that the number of obtained iridium nanoclusters is indeed small.

[0115] Example 6

[0116] The preparation method of rhodium nanoclusters in this embodiment includes:

[0117] (1) Prepare the aqueous phase containing rhodium salt: 23 mg, 0.09 mmol hydrated rhodium chloride (RhCl 3 ·H 2 (2) was dissolved in 50mL deionized water and stirred for 30min to fully dissolve the rhodium chloride hydrate.

[0118] (2) Phase transfer: add 1.5 mL of dodecylamine to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing dodecylamine to the deionized water containing rhodium ions, and add 50 mL of n-hexane solution at the same time, stir vigorously for 30 min, and then stand for 20 min, wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Repeat the above phase transfer operation to prepare the n-hexane solution containing rhodium ions three times, then gather these n-hexane solutions together, stir at 1500 rpm / min, increase the temperature to 80°C and heat for 5 h to concentrate, and the volume of the organic phase after concentration is 5 mL.

[0119] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 270°C and maintain it for 2 hours.

[0120] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing rhodium nanoclusters, ultrasonically shaken for 30 min, and then centrifuged at a speed of 10,000 rpm / min. Finally, the rhodium nanoclusters obtained by centrifugation are redispersed in an n-hexane solution for preservation.

[0121] like Figure 6 As shown, the average particle size of rhodium nanoparticles is 2.1 nm, which indicates that the rhodium prepared by this method is also a nanocluster with good dispersion.

[0122] Example 7

[0123] The preparation method of ruthenium nanoclusters in this embodiment includes:

[0124] (1) Preparation of aqueous phase containing ruthenium salt: 25 mg, 0.09 mmol hydrated ruthenium chloride (RuCl 3 ·H 2 (0) was dissolved in 50 mL of deionized water and stirred for 30 min to fully dissolve the hydrated ruthenium chloride.

[0125] (2) Phase transfer: Add 1.5 mL of dodecylamine to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing dodecylamine to the deionized water containing rhodium ions, and add 50 mL of n-hexane solution at the same time. Stir vigorously for 30 min and let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Repeat the above phase transfer operation to prepare the n-hexane solution containing ruthenium ions three times, then gather these n-hexane solutions together, stir at 1500 rpm / min, increase the temperature to 80°C and heat for 5 h to concentrate, and the volume of the organic phase after concentration is 5 mL.

[0126] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 250°C and maintain it for 2 hours.

[0127] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing ruthenium nanoclusters, ultrasonically shaken for 30 min, and then centrifuged at a speed of 10,000 rpm / min. Finally, the ruthenium nanoclusters obtained by centrifugation are redispersed in n-hexane solution for preservation.

[0128] like Figure 7As shown, the average particle size of ruthenium nanoparticles is 2.05 nm, which indicates that the ruthenium prepared by this method is also a nanocluster with good dispersion.

[0129] Example 8

[0130] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0131] (2) Phase transfer: Add 3 mL of dodecylamine to 50 mL of deionized water, stir for 10 min, then add 50 mL of n-hexane solution, stir vigorously for 30 min, and then let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Then, repeat the above phase transfer operation to prepare n-hexane solutions containing iridium ions in three batches, then pool these n-hexane solutions together, stir at 1500 rpm / min, raise the temperature to 80°C and heat for 5 h for concentration. After concentration, the volume of the organic phase is 5 mL.

[0132] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask, add 15 mL of octadecene, and heat under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 230°C and maintain it for 2 hours.

[0133] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing the iridium nanoclusters, ultrasonically shaken for 30 min, and then centrifuged at a speed of 10,000 rpm / min. Finally, the iridium nanoclusters obtained by centrifugation are redispersed in a n-hexane solution for preservation.

[0134] It can be seen from Table 5 that when no amphoteric solvent is added, the phase transfer efficiency is seriously reduced, indicating that the amphoteric solvent is crucial to improving the phase transfer efficiency.

[0135] Table 5. Iridium ion phase transfer efficiency

[0136]

[0137] Example 9

[0138] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6) was dissolved in 50 mL of deionized water and stirred for 30 min to fully dissolve potassium chloroiridate. (2) Phase transfer: 3 mL of polyethylene glycol was added to 50 mL of ethanol and stirred for 10 min to fully dissolve it. Then, the ethanol solution containing polyethylene glycol was added to the deionized water containing iridium ions and 50 mL of n-hexane solution was added. After vigorous stirring for 30 min, it was allowed to stand for 20 min until the aqueous phase and the organic phase were completely separated and the aqueous phase became transparent. The upper layer was aspirated into a beaker.

[0139] It can be seen from Table 6 that the phase transfer efficiency when the phase transfer agent is polyethylene glycol is 99.48%, and the phase transfer effect is very good.

[0140] Table 6. Iridium ion phase transfer efficiency

[0141]

[0142] Comparative Example 1

[0143] The preparation method of iridium nanoparticles in this comparative example includes:

[0144] Aqueous phase synthesis: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min, then 100 mg of sodium borohydride and 120 mg of activated carbon were added to the water and stirred vigorously for 60 min. Stirring was stopped after the solution turned gray-black and no longer changed, 20 mL of anhydrous ethanol was added to the aqueous solution, and then the iridium nanoparticles were collected by centrifugation at a speed of 10000 rpm / min.

[0145] Figure 8 This is a transmission electron microscope image of the iridium nanoparticles in Comparative Example 1 of the present disclosure, such as Figure 8 As shown, the iridium nanoparticles generated by direct reduction of iridium in water phase are easy to agglomerate and have a larger particle size.

[0146] Comparative Example 2

[0147] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0148] (2) Phase transfer: Add 3 mL of dodecylamine to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing dodecylamine to the deionized water containing iridium ions, and add 50 mL of n-hexane solution at the same time. Stir vigorously for 30 min and let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Repeat the above phase transfer operation to prepare the n-hexane solution containing iridium ions three times, then gather these n-hexane solutions together, stir at 1500 rpm / min, increase the temperature to 80°C and heat for 5 h to concentrate. After concentration, the volume of the organic phase is 15 mL.

[0149] (3) Thermal reduction: Place the concentrated n-hexane solution in a beaker, add 100 mg of sodium borohydride, and react for 10 min under stirring at 500 rpm / min.

[0150] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing iridium nanoparticles, ultrasonically shaken for 30 minutes, and then centrifuged at a speed of 10,000 rpm / min. Finally, the iridium nanoparticles obtained by centrifugation are redispersed in a n-hexane solution for preservation.

[0151] Fig. 9 This is a transmission electron microscope image of the iridium nanoparticles in Comparative Example 2 of the present disclosure, such as Fig. 9 It can be seen that the iridium nanoparticles generated by direct reduction of iridium ions with sodium borohydride after phase transfer are uneven in size and irregularly spherical, and the particles are agglomerated.

[0152] Comparative Example 3

[0153] (1) Prepare the aqueous phase containing iridium salt: 72 mg, 0.15 mmol potassium chloroiridate (K 2 IrCl 6 ) was dissolved in 50 mL of deionized water and stirred for 30 min to allow potassium chloroiridate to fully dissolve.

[0154] (2) Phase transfer: Add 3 mL of dodecylamine to 50 mL of ethanol, stir for 10 min to fully dissolve it, then add the ethanol solution containing dodecylamine to the deionized water containing iridium ions, and add 50 mL of n-hexane solution at the same time. Stir vigorously for 30 min and let stand for 20 min. Wait until the aqueous phase and the organic phase are completely separated and the aqueous phase becomes transparent, and then absorb the upper liquid into a beaker. Repeat the above phase transfer operation 3 times to prepare n-hexane solutions containing iridium ions multiple times, then gather these n-hexane solutions together, stir at 1500 rpm / min, increase the temperature to 80°C and heat for 5 h to concentrate. After concentration, the volume of the organic phase is 5 mL.

[0155] (3) Thermal reduction: Place the concentrated n-hexane solution in a three-necked flask and heat it under the protection of high-purity Ar gas. First, raise the temperature to 120°C and maintain it for 30 minutes to remove water and impurities in the solvent and evaporate the n-hexane. Then raise the temperature to 230°C and maintain it for 2 hours.

[0156] (4) Dispersion and preservation: After the reaction is completed, 15 mL of n-hexane and 30 mL of anhydrous ethanol are added to the solution containing iridium nanoparticles, ultrasonically shaken for 30 minutes, and then centrifuged at a speed of 10,000 rpm / min. Finally, the iridium nanoparticles obtained by centrifugation are redispersed in the n-hexane solution, and then 20 mg of activated carbon is added for loading.

[0157] like Fig.10 The transmission electron microscope picture shown in the figure shows that without adding the second organic solvent octadecene, the obtained iridium nanoparticles have a larger particle size and uneven morphology and size, indicating that octadecene has a great influence on the morphology and size of the iridium nanoparticles.

[0158] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for preparing platinum group metal nanoclusters, include: Using a phase transfer agent to transfer the platinum group metal salt in the water phase to a first organic solvent that is immiscible with water to obtain an organic phase, wherein the phase transfer agent is an alcohol, an ammonium salt or an amine compound; A second organic solvent is added to the organic phase, and the mixture is heated under an inert atmosphere, so that when the first organic solvent is evaporated, the platinum group metal salt in the second organic solvent is reduced by the phase transfer agent to obtain the platinum group metal nanoclusters.

2. The method according to claim 1, in, The phase transfer agent is at least one of polyethylene glycol, ethylene glycol, octadecyl mercaptan, dodecyl mercaptan, tetrabutylammonium bromide, trioctylammonium chloride, hexadecyltrimethylammonium bromide, tributylammonium, dodecylamine and octadecylamine.

3. The method according to claim 1, in, The heating under an inert atmosphere so that when the first organic solvent is evaporated, the platinum group metal salt in the second organic solvent is reduced by the phase transfer agent comprises: Under an inert atmosphere, the organic phase containing the second organic solvent is heated by a staged heating method; wherein the first organic solvent is evaporated in a first heating stage, and the platinum group metal salt in the second organic solvent is reduced by the phase transfer agent in a second heating stage.

4. The method according to claim 3, in, The final temperature of the first temperature rising stage is 50-200°C, and the final temperature of the second temperature rising stage is 180-300°C.

5. The method according to claim 1, 3 or 4, in, The second organic solvent has a C10-C20 long-chain hydrocarbon group, and the volume ratio of the second organic solvent to the phase transfer agent is 3 / 1-8 / 1. The second organic solvent is preferably selected from at least one of octadecene, lecithin, and oleic acid.

6. The method according to claim 1, in, Before adding the second organic solvent to the organic phase, the method further comprises: Repeat the phase transfer operation, combine the organic phases obtained from multiple phase transfers, and then concentrate to obtain a concentrated organic phase. After concentration, the concentration of the platinum group metal in the organic phase is 10-15 g / L.

7. The method according to claim 6, in, The concentration operation includes: evaporating the combined organic phase by stirring or rotary evaporation at normal pressure or negative pressure and a temperature of 0 to 100° C.

8. The method according to any one of claims 1 to 4, 6 to 7, in, The method of transferring the platinum group metal salt in the aqueous phase to a first organic solvent immiscible with water using a phase transfer agent to obtain an organic phase comprises: The amphoteric solvent containing the phase transfer agent is added to the aqueous solution of the platinum group metal salt, and then the first organic solvent is added and stirred. After stirring, the mixture is allowed to stand for stratification to obtain the organic phase containing the platinum group metal salt.

9. The method according to claim 8, in: The volume ratio of the phase transfer agent to the amphoteric solvent is 1:10 to 1:100, preferably 1:10 to 1:30; and / or The amphoteric solvent is at least one of alcohol, amide, and ether solvents, preferably at least one selected from ethanol, methanol, isopropanol, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, and tetrahydrofuran.

10. The method according to any one of claims 1-4, 6-7, 9, in: The concentration of the platinum group metal salt in the aqueous phase is 0.2 to 10 g / L, preferably 1 to 5 g / L; and / or The volume ratio of the phase transfer agent to the aqueous phase is 1:10 to 1:100, preferably 1:10 to 1:

30.

11. The method according to any one of claims 1-4, 6-7, 9, in, The first organic solvent is selected from at least one of alkanes, benzenes, halogenated hydrocarbons, and ether solvents, preferably at least one of hexane, cyclohexane, toluene, chloroform, and diethyl ether. The volume ratio of the first organic solvent to the aqueous phase is 2 / 1 to 1 / 3.

12. The method according to any one of claims 1-4, 6-7, and 9, further comprising: include: After the reduction reaction is completed, a washing solvent and a precipitant are added to the second organic solvent containing the platinum group metal nanoclusters, and ultrasonic vibration is performed to separate and obtain the dispersed platinum group metal nanoclusters.

13. The method according to claim 12, in: The washing solvent is selected from hexane, acetone, cyclohexane or n-pentane; The precipitant is selected from methanol, ethanol and isopropanol.

14. The method according to any one of claims 1-4, 6-7, 9, 13, in, The platinum group metal salt is a chloride complex of iridium, rhodium, platinum, palladium, ruthenium or osmium.

15. A platinum group metal nanocluster prepared by the method according to any one of claims 1 to 14.

16. Use of the platinum group metal nanoclusters as claimed in claim 15 as catalysts in the fields of fuel cells, water electrolysis, catalytic hydrogenation, corrosion-resistant coatings, chiral medicines and pesticides.

Images