A platinum nanocluster and a preparation method thereof

Abstract

The present invention provides a core-shell Pt6(PR)4Cl4 cluster with a regular octahedral Pt6 core, and the cluster is a platinum cluster protected by phosphine ligands and chlorine atoms. The cluster consists of 6 platinum atoms forming a unique regular octahedral core, which is protected by 8 phosphorus atoms and 4 chlorine atoms. The present invention further discloses a preparation method of the Pt6(PR)4Cl4 cluster. Through the present invention, a platinum cluster with a precisely structured regular octahedral core is synthesized for the first time, and the present invention has high innovation value.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial preparation, and more particularly to a platinum nanocluster and a preparation method thereof. Background Art

[0002] Platinum metal is a key component of many catalysts in industrial processes and commercial devices. However, due to its extremely low reserves and high cost in nature, its application is greatly limited. Modifying platinum at the nanoscale can effectively improve its utilization rate and catalytic performance. Nano metal clusters are a class of ultrasmall nanoparticles with a precisely controllable structure and a size of less than 3 nm. By using the idea of designing nanoclusters, atomic-level regulation of platinum can be achieved, and its catalytic activity is expected to be improved.

[0003] Currently, the synthesis of platinum nanoclusters with a definite number of platinum atoms and appropriate surface chemical properties remains a long-term challenge. This is probably because freshly generated platinum atoms have active catalytic activity, which can induce the deposition and catalytic decomposition of reducing agents (such as sodium borohydride) in most reduction synthesis strategies, making it difficult to control the controllable growth of Pt nanoclusters. Therefore, it is crucial to synthesize platinum nanoclusters with a precise structure. Summary of the Invention

[0004] To solve the above problems, in the first aspect of the present invention, a platinum nanocluster is provided. The cluster is a platinum nanocluster protected by phosphorus atoms and chlorine atoms, with an octahedral core composed of 6 platinum atoms, and a synergistic protection structure formed by 4 phosphine ligands and 4 chlorine atoms.

[0005] Preferably, the chemical formula of the platinum nanocluster is Pt6Cl4(P2C 25 H 22 )4, belonging to the monoclinic system, with the space group C2 / c. The crystallographic parameters of the single crystal are: α = 90°, β = 97.898(5), γ = 90°.

[0006] Compared with existing platinum clusters, the platinum cluster of the present invention has the following advantages:

[0007] (1) The Pt6(PR)4Cl4 cluster provided by the present invention is the first reported platinum cluster with an octahedral Pt6 core; (2) The cluster provided by the present invention is different from the platinum clusters synthesized by the template method in the past. The Pt6(PR)4Cl4 cluster has a synergistic protection structure composed of an octahedral platinum core and P and Cl atoms; (3) Thanks to the protection of the ligand, the cluster can maintain high dispersibility during the electrocatalytic process and exhibit excellent catalytic activity.

[0008] In the second aspect of the present invention, a preparation method of the aforementioned platinum nanocluster is provided, including the following steps:

[0009] S1: Dissolve divalent cadmium salt in an organic solvent, stir until dissolved, then add an aqueous solution of chloroplatinic acid, and stir the solution at a constant temperature to obtain solution A;

[0010] S2: Dissolve tetraoctylammonium bromide in an organic solvent, stir until dissolved to obtain solution B;

[0011] S3: Add a phosphine ligand to solution B obtained in step S2, and stir to obtain a turbid liquid C;

[0012] S4: Add a reducing agent to turbid liquid C obtained in step S3, stir at a constant temperature to obtain turbid liquid D;

[0013] S5: Centrifuge turbid liquid D to obtain a clear liquid E;

[0014] S6: Perform single crystal cultivation on clear liquid E to obtain platinum nanoclusters.

[0015] Preferably, in step S1, the organic solvent is methanol, the divalent cadmium salt is cadmium chloride, and the molar ratio of the divalent cadmium salt to the chloroplatinic acid is (0.1 - 5):1; the stirring temperature is 0 - 40°C, the stirring rate is 400 - 1000 r / min, and the stirring reaction time is 10 - 60 min.

[0016] Preferably, in step S2, the molar ratio of the tetraoctylammonium bromide to the chloroplatinic acid is (1 - 10):1; the stirring temperature is 0 - 40°C, the stirring rate is 400 - 1000 r / min, and the stirring reaction time is 10 - 60 min.

[0017] Preferably, in step S3, the phosphine ligand is bis(diphenylphosphino)methane, and the molar ratio of the phosphine ligand to the chloroplatinic acid is (1 - 10):1; the stirring temperature is 0 - 40°C, the stirring rate is 400 - 1000 r / min, and the stirring reaction time is 10 - 60 min.

[0018] Preferably, in step S4, the reducing agent is borane tert-butylamine complex, and the molar ratio of the borane tert-butylamine complex to the chloroplatinic acid is (1 - 100):1; the stirring temperature is 0 - 40°C, the stirring rate is 400 - 1000 r / min, and the stirring reaction time is 10 - 60 min.

[0019] The preparation method provided by the present invention has a simple process flow, does not require cumbersome equipment and operations, and can prepare platinum clusters with a synthetic octahedral core. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the structure of the Pt6(PR)4Cl4 cluster. Detailed Embodiments

[0021] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of specific embodiments of the present invention is provided. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the protection scope of the claims of the present invention.

[0022] It should be noted that the endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] The present invention provides a platinum nanocluster with a regular octahedral metal core. The cluster is a platinum nanocluster protected by bis(diphenylphosphino)methane and chlorine atoms. The cluster consists of 6 platinum atoms forming a regular octahedral core, and is synergistically protected by 4 phosphine ligands and 4 chlorine atoms.

[0024] The present invention also provides a method for preparing the above platinum nanocluster, including the following steps:

[0025] S1: Dissolve divalent cadmium salt in an organic solvent, stir until dissolved, and then add an aqueous solution of chloroplatinic acid. The solution is stirred at a constant temperature to obtain solution A;

[0026] S2: Dissolve tetraoctylammonium bromide in an organic solvent, stir until dissolved, to obtain solution B;

[0027] S3: Add a phosphine ligand to solution B obtained in step S2, and stir to obtain a turbid solution C;

[0028] S4: Add a reducing agent to turbid solution C obtained in step S3, and stir at a constant temperature to obtain turbid solution D;

[0029] S5: Centrifuge turbid solution D to obtain a clear solution E;

[0030] S6: Perform single crystal cultivation on clear solution E to obtain platinum nanoclusters.

[0031] The above technical solutions of the present invention are expanded and described below in combination with specific actual data.

[0032] Example 1

[0033] This example provides a Pt6(PR)4Cl4 cluster with an octahedral metal core and a preparation method thereof, including the following steps:

[0034] S1: Add 10 ml of methanol and 35 mg of cadmium chloride dihydrate to a 25 ml flask. After stirring and dissolving, add 20 mg of chloroplatinic acid dissolved in 200 μL of water, and stir at 800 rpm for 30 min at room temperature.

[0035] S2: Take 50 mg of tetraoctylammonium bromide and add it to the reaction solution in step S1, and stir and react at a uniform speed of 800 rpm for 30 min.

[0036] S3: Add 50 mg of bis(diphenylphosphino)methane, and stir and react at a uniform speed of 800 rpm for 30 min.

[0037] S4: Add 200 mg of borane tert-butylamine complex to reduce metal ions. Stir and react at a uniform speed of 800 rpm for 10 h.

[0038] S5: Take out the reaction solution and centrifuge and wash it multiple times.

[0039] S6: Place the supernatant in a methanol / n-hexane system to grow single crystals. After two weeks, black rod-shaped single crystals grow.

[0040] Example 2

[0041] This example provides a Pt6(PR)4Cl4 cluster with an octahedral metal core and a preparation method thereof, including the following steps:

[0042] S1: Add 10 ml of methanol and 70 mg of cadmium chloride dihydrate to a 25 ml flask. After stirring and dissolving, add 40 mg of chloroplatinic acid dissolved in 400 μL of water, and stir at 800 rpm for 30 min at room temperature.

[0043] S2: Take 50 mg of tetraoctylammonium bromide and add it to the reaction solution in step S1, and stir and react at a uniform speed of 800 rpm for 30 min.

[0044] S3: Add 50 mg of bis(diphenylphosphino)methane, and stir and react at a uniform speed of 800 rpm for 30 min.

[0045] S4: Add 200 mg of borane tert-butylamine complex to reduce metal ions. Stir and react at a uniform speed of 800 rpm for 10 h.

[0046] S5: Take out the reaction solution and centrifuge and wash it multiple times.

[0047] S6: Place the supernatant in a methanol / n-hexane system to grow single crystals. After two weeks, black rod-shaped single crystals grow.

[0048] Example 3

[0049] This example provides a Pt6(PR)4Cl4 cluster with an octahedral metal core and its preparation method, which are as follows:

[0050] The preparation method includes the following steps:

[0051] S1: Add 10 ml of methanol and 35 mg of cadmium chloride dihydrate to a 25 ml flask. After stirring and dissolving, add 20 mg of chloroplatinic acid dissolved in 200 μL of water, and stir at 800 rpm for 30 min at room temperature.

[0052] S2: Take 100 mg of tetraoctylammonium bromide and add it to the reaction solution in step S1, and stir and react at a uniform speed of 800 rpm for 60 min.

[0053] S3: Add 50 mg of bis(diphenylphosphino)methane, and stir and react at a uniform speed of 800 rpm for 30 min.

[0054] S4: Add 200 mg of borane tert-butylamine complex to reduce metal ions. Stir and react at a uniform speed of 800 rpm for 10 h.

[0055] S5: Take out the reaction solution, and centrifuge and wash it multiple times.

[0056] S6: Place the supernatant in a methanol / n-hexane system to grow single crystals. After two weeks, black rod-shaped single crystals grow.

[0057] Example 4

[0058] This example provides a Pt6(PR)4Cl4 cluster with an octahedral metal core and its preparation method, which are as follows:

[0059] The preparation method includes the following steps:

[0060] S1: Add 10 ml of methanol and 35 mg of cadmium chloride dihydrate to a 25 ml flask. After stirring and dissolving, add 20 mg of chloroplatinic acid dissolved in 200 μL of water, and stir at 800 rpm for 30 min at room temperature.

[0061] S2: Take 100 mg of tetraoctylammonium bromide and add it to the reaction solution in step S1, and stir and react at a uniform speed of 800 rpm for 60 min.

[0062] S3: Add 50 mg of bis(diphenylphosphino)methane, and stir and react at a uniform speed of 800 rpm for 30 min.

[0063] S4: Add 100 mg of borane tert-butylamine complex to reduce metal ions. Stir and react at a uniform speed of 800 rpm for 10 h.

[0064] S5: Take out the reacted solution and centrifuge and wash it multiple times.

[0065] S6: Place the supernatant in a methanol / n-hexane system to grow single crystals. Black rod-shaped single crystals grow out after two weeks.

[0066] The crystal structures of the Pt6(PR)4Cl4 clusters with octahedral metal cores prepared in Example 1, Example 2, Example 3, and Example 4 are all as Figure 1 shown. It can be seen from Figure 1 that the cluster is a platinum cluster protected by bis(diphenylphosphino)methane. The cluster consists of an octahedral core composed of 6 platinum atoms, protected by 8 phosphorus atoms and 4 chlorine atoms.

[0067] The crystal data of the crystal prepared in Example 1 are shown in Table 1 below:

[0068] Table 1 Crystallographic parameters of the crystal in Example 1

[0069]

[0070]

[0071] Through the specific experimental data of the above Examples 1-4, the Pt6(PR)4Cl4 cluster crystals with an octahedral Pt6 core prepared are further proved that the present invention provides a platinum cluster crystal with an accurate structure, and this platinum cluster crystal is the first reported platinum cluster crystal.

[0072] The above has described the preferred embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the spirit of the present invention. It is not necessary and impossible to enumerate all the embodiments here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for preparing platinum nanoclusters, characterized in that, Comprising the following steps: S1: Dissolve cadmium chloride in methanol, stir until dissolved, and then add an aqueous solution of chloroplatinic acid. Stir the solution at a constant temperature to obtain solution A. Among them, the molar ratio of cadmium chloride to chloroplatinic acid in solution A is (0.1 - 5):1; S2: Dissolve tetraoctylammonium bromide in solution A, stir until dissolved to obtain solution B. Among them, the molar ratio of tetraoctylammonium bromide to chloroplatinic acid in solution B is (1 - 10):1; S3: Add bis(diphenylphosphino)methane to solution B obtained in step S2, and stir to obtain turbid liquid C. Among them, the molar ratio of bis(diphenylphosphino)methane to chloroplatinic acid in solution C is (1 - 10):1; S4: Add a reducing agent to turbid liquid C obtained in step S3, stir at a constant temperature to obtain turbid liquid D; S5: Centrifuge turbid liquid D to obtain clear liquid E; S6: Carry out single crystal cultivation on clear liquid E to obtain platinum nanoclusters.

2. The preparation method of the platinum nanoclusters according to claim 1, characterized in that, The temperature of stirring is 0 - 40 °C, the stirring rate is 400 - 1000 r / min, and the stirring reaction time is 10 - 60 min.

3. The preparation method of the platinum nanoclusters according to claim 1, characterized in that: In step S4, the reducing agent is borane tert-butylamine complex.

4. The preparation method of the platinum nanoclusters according to claim 1, wherein, The molar ratio of the reducing agent to chloroplatinic acid is (1 - 100):1, the temperature of stirring is 0 - 40 °C, the stirring rate is 400 - 1000 r / min, and the stirring reaction time is 10 - 60 min.

5. A platinum nanocluster, characterized in that, The platinum nanoclusters are prepared by the preparation method according to any one of claims 1 to 4. The platinum nanoclusters are platinum nanoclusters protected by phosphorus atoms and chlorine atoms, with a regular octahedron core composed of 6 platinum atoms, and a synergistic protection structure formed by 4 phosphine ligands and 4 chlorine atoms.

6. The platinum nanoclusters according to claim 5, characterized in that, The chemical formula of the platinum nanocluster is Pt6Cl4(P2C 25 H 22 )4, which belongs to the monoclinic system with the space group C2 / c. The crystallographic parameters of the single crystal are as follows: a = 50.219(5) Å, b = 21.810(2) Å, c = 19.8019(19) Å, α = 90°, β = 97.898(5), γ = 90°.

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