Preparation method of two-dimensional material loaded single-atom layer noble metal catalyst

Abstract

The application discloses a preparation method of a two-dimensional material loaded single-atom layer noble metal catalyst, which comprises the following steps: uniformly dispersing noble metal nanoclusters and a metal single crystal carrier in a solvent to obtain a first mixed solution; adding a two-dimensional material into the first mixed solution to obtain a second mixed solution; and adding an etching agent into the second mixed solution, and performing etching reaction and standing and aging to obtain the two-dimensional material loaded single-atom layer noble metal catalyst. Experiments show that the method has universality and high efficiency, does not need complex reaction devices and steps, can prepare independent two-dimensional nanomaterials with sub-nanometer thickness at normal temperature, and opens up an innovative way to atomic-level thin metal nanomaterials.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and in particular to a method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst. Background Technology

[0002] With the discovery of graphene, research on two-dimensional nanosheets is progressing rapidly. The study of two-dimensional nanomaterials has had a profound impact on many different scientific fields, including lithium-ion batteries and catalysis. The atomic-scale thickness exposes almost all atoms on the surface, providing the material with an extremely high specific surface area. Furthermore, the dramatic increase in surface area affects the wave function of quantum confinement effects, resulting in unique electronic, photonic, magnetic, and catalytic properties. Currently, two-dimensional nanomaterials have been prepared and applied in various forms, including but not limited to graphene, layered oxides and hydroxides, layered metal-organic frameworks, and their derivatives.

[0003] As the first planar nanosheet discovered in nature, graphene is a prime example of two-dimensional nanomaterials. Compared to three-dimensional graphite nanosheets, its electrical conductivity and thermal conductivity are 3 to 5 orders of magnitude higher, demonstrating unparalleled advantages. This has sparked considerable interest in the research of various two-dimensional nanomaterials. Two-dimensional metal-free materials such as C3N4 and BN4, as well as a series of metal compounds, have gradually emerged in the exploration of two-dimensional nanomaterials, exhibiting excellent performance in energy conversion and storage, demonstrating the enormous potential of the two-dimensional nanomaterial family. Meanwhile, the experimental acquisition of elemental two-dimensional nanomaterials such as phosphorene and boronene nanosheets has revealed unexpected physical, chemical, and optoelectronic properties, further stimulating interest. These emerging two-dimensional nanomaterials not only possess excellent semiconductor properties, potentially making significant contributions to optoelectronics, but also hold broad prospects in catalysis and biomedicine.

[0004] Research has shown that when a certain dimension of a noble metal material reaches the nanoscale, it often exhibits properties drastically different from those of ordinary metal crystals. At the scale of two-dimensional nanosheets, the high specific surface area and efficient atomic utilization of noble metal materials demonstrate enormous potential in catalysis.

[0005] Although some progress has been made in the research of two-dimensional nanomaterials, large-scale production with high purity remains a major challenge in the synthesis process. In existing technologies, loading single-atom-layer noble metals onto two-dimensional materials often requires high-temperature calcination, which is cumbersome. How to efficiently prepare high-quality atomic-scale two-dimensional metal nanosheets at room temperature remains a significant challenge.

[0006] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst, which aims to solve the problems of cumbersome operation and high temperature requirements in the preparation of existing two-dimensional material-supported single-atom-layer noble metal catalysts.

[0008] The technical solution of the present invention is as follows:

[0009] This invention provides a method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst, comprising:

[0010] The noble metal nanoclusters and the metal single crystal carrier are uniformly dispersed in a solvent to obtain the first mixed solution;

[0011] A two-dimensional material is added to the first mixed solution to obtain a second mixed solution;

[0012] An etchant was added to the second mixed solution, and after etching and aging, a two-dimensional material-supported monolayer noble metal catalyst was obtained.

[0013] Optionally, the mass ratio of the noble metal nanoclusters, the metal single crystal carrier, and the two-dimensional material is 1:(6-10):(12-20).

[0014] Optionally, the metal single crystal carrier is copper (111) or gold (111).

[0015] Optionally, the solvent is selected from one or more of ethanol, methanol, and dichloromethane.

[0016] Optionally, the two-dimensional material is selected from one or more of graphene, molybdenum disulfide, and MXene.

[0017] Optionally, the etching agent is selected from one or more of nitric acid and ferric chloride solution.

[0018] Optionally, the method for preparing the noble metal nanoclusters includes:

[0019] The noble metal salt and ligand molecules are dissolved in the reaction solvent to obtain a complex solution;

[0020] A reducing agent was added dropwise to the complex solution to obtain the noble metal nanoclusters.

[0021] Optionally, the noble metal salt is selected from one or more of chloroplatinic acid, palladium acetate, and silver nitrate.

[0022] Optionally, the ligand molecule is selected from one or more of L-reduced glutathione, poly(N-vinyl-2-pyrrolidone), and 4-tert-butylthiophenol.

[0023] Optionally, the reducing agent is sodium borohydride.

[0024] Optionally, the reaction solvent is selected from one or more of water, ethanol, and tetrahydrofuran.

[0025] Optionally, the method for preparing the metal single crystal support includes:

[0026] The metal salt and vitamin C are dissolved in water to obtain a reaction solution;

[0027] Hexamethylenetetramine and cetyltrimethylammonium bromide were added to the reaction solution, and the mixture was heated and washed to obtain the metal single crystal support.

[0028] Optionally, the heating reaction is carried out at a temperature of 60-80°C for 3-5 hours.

[0029] Beneficial effects: This invention provides a method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst. The advantages of this preparation method are mainly: 1) simple operation process and friendly working environment; 2) simple operating instruments and low operating cost; 3) universality for different types of clusters; 4) less temperature limitation and no need for high temperature conditions for reaction. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the operation process of the present invention.

[0031] Figure 2 This is a SEM characterization image of the copper (111) support in Example 1 of the present invention.

[0032] Figure 3 The graph shows the electrochemical performance test results of the carbon-supported platinum atomic layer in Example 1 of this invention.

[0033] Figure 4 This is a comparison chart of the mass specific activity of the carbon-supported platinum atomic layer and the commercial platinum-carbon catalyst in Example 1 of the present invention.

[0034] Figure 5 This is an STM characterization image of the carbon-supported palladium atomic layer in Example 2 of the present invention.

[0035] Figure 6 This is a TEM characterization image of the palladium-silver cluster in Example 3 of the present invention. Detailed Implementation

[0036] This invention provides a method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0037] This invention provides a method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst, comprising:

[0038] The noble metal nanoclusters and the metal single crystal carrier are uniformly dispersed in a solvent to obtain the first mixed solution;

[0039] A two-dimensional material is added to the first mixed solution to obtain a second mixed solution;

[0040] An etchant was added to the second mixed solution, and after etching and aging, a two-dimensional material-supported monolayer noble metal catalyst was obtained.

[0041] Specifically, this invention loads noble metal nanoclusters onto a two-dimensional material using a metal single-crystal support, and then removes the metal single-crystal support using an etchant to obtain a two-dimensional material-loaded single-atom-layer noble metal catalyst. The principle is that, compared to two-dimensional material substrates, metal single-crystal supports are more suitable for the growth of single-atom-layer noble metals. However, in terms of performance, two-dimensional materials such as graphene still perform better as substrates. Therefore, a metal single-crystal support is chosen as a transitional step to ultimately complete the loading onto the two-dimensional material.

[0042] In one embodiment, the mass ratio of the noble metal nanoclusters, the metal single crystal carrier, and the two-dimensional material is 1:(6-10):(12-20).

[0043] In one embodiment, the metal single crystal carrier is copper (111) or gold (111), including but not limited to these.

[0044] In one embodiment, the solvent is selected from one or more of ethanol, methanol, and dichloromethane.

[0045] Specifically, the solvent enables the noble metal nanoclusters to be uniformly adsorbed onto the metal single crystal support, and then loaded onto the two-dimensional material. The specific type of solvent can be selected according to experimental needs, including but not limited to this.

[0046] In one embodiment, the two-dimensional material is selected from one or more of graphene, molybdenum disulfide, and MXene.

[0047] Specifically, the present invention does not impose strict restrictions on the structure of two-dimensional materials, and those skilled in the art can choose and adjust them according to the existing situation, including but not limited to this.

[0048] In one embodiment, the etchant is selected from one or more of nitric acid and ferric chloride solution.

[0049] In one embodiment, the method for preparing the noble metal nanoclusters includes:

[0050] The noble metal salt and ligand molecules are dissolved in the reaction solvent to obtain a complex solution;

[0051] A reducing agent was added dropwise to the complex solution to obtain the noble metal nanoclusters.

[0052] Specifically, the preparation method of noble metal nanoclusters in this invention is a prior art. The material addition ratio varies for different clusters, and existing mature methods can be referenced for preparation. The reducing agent used is usually in excess, and it is added dropwise to control the reduction rate and prevent the product from agglomerating into large particles.

[0053] In one embodiment, the noble metal salt is selected from one or more of chloroplatinic acid, palladium acetate, and silver nitrate.

[0054] In one embodiment, the ligand molecule is selected from one or more of L-reduced glutathione, poly(N-vinyl-2-pyrrolidone), and 4-tert-butylthiophenol.

[0055] In one embodiment, the reducing agent is sodium borohydride.

[0056] Specifically, the role of the reducing agent is to reduce the complex of noble metal salt and ligand molecules into noble metal nanoclusters. It is usually in excess relative to the noble metal salt, and the specific type can be selected according to experimental needs, including but not limited to this.

[0057] In one embodiment, the reaction solvent is selected from one or more of water, ethanol, and tetrahydrofuran.

[0058] Specifically, the role of the reaction solvent is to dissolve the noble metal salt and ligand molecules. The specific type can be selected according to experimental needs, including but not limited to this.

[0059] In one embodiment, the method for preparing the metal single crystal carrier includes:

[0060] The metal salt and vitamin C are dissolved in water to obtain a reaction solution;

[0061] Hexamethylenetetramine and cetyltrimethylammonium bromide were added to the reaction solution, and the mixture was heated and washed to obtain the metal single crystal support.

[0062] In one embodiment, the heating reaction is carried out at a temperature of 60-80°C for 3-5 hours.

[0063] In one embodiment, the method for preparing the two-dimensional material-supported monolayer noble metal catalyst specifically includes:

[0064] Step (1), Preparation of noble metal nanoclusters:

[0065] The noble metal salt and ligand molecules are dissolved in the reaction solvent and mixed thoroughly to obtain a complex solution. A reducing agent is added dropwise to the complex solution under vigorous stirring to carry out a reduction reaction. After reacting for 2-20 hours, the crude product is obtained by rotary evaporation. The crude product is then repeatedly washed and purified with a detergent to obtain noble metal nanoclusters.

[0066] Step (2), Preparation of the copper (111) support:

[0067] Copper nitrate and vitamin C were dissolved in water to obtain a reaction solution; hexamethylenetetramine and hexadecyltrimethylammonium bromide were added to the reaction solution, and the mixture was stirred in an oil bath at 60-80°C for 3-5 hours to obtain a copper (111) support.

[0068] Step (3), Loading of a noble metal monolayer on a two-dimensional material:

[0069] Noble metal nanoclusters were uniformly dispersed in a solvent, and a copper (111) support was added and thoroughly mixed to obtain a first mixed solution. Two-dimensional material was added to the first mixed solution and stirred thoroughly to obtain a second mixed solution. An etchant was added to the second mixed solution, and after stirring thoroughly to react, the solution was allowed to stand for 2-24 hours to obtain a post-reaction solution. The post-reaction solution was centrifuged and washed several times, and the resulting solid was dried in an oven at 60-80℃ to obtain a two-dimensional material-supported monolayer noble metal catalyst.

[0070] In one embodiment, unless otherwise stated, the preparation of the two-dimensional material-supported monolayer noble metal catalyst is carried out at room temperature (20-30°C). This invention does not limit the operating conditions; any condition where the noble metal cluster and the two-dimensional material substrate structure are stable is acceptable, with room temperature being the most preferred condition.

[0071] The present invention will be further described below through specific embodiments.

[0072] Example 1

[0073] This embodiment provides a method for loading a platinum single-atom layer on a graphene substrate, the specific process of which includes:

[0074] (1) Preparation of platinum clusters Pt5(SG) using mature preparation technology 10 A 0.5 mmol aqueous solution of chloroplatinic acid (H₂PtCl₆·H₂O) was mixed with a 1.5 mmol aqueous solution of L-reduced glutathione (L-SG), and stirred at 0 °C for 2 h. Under vigorous stirring, 3 mmol of an ice-cold aqueous solution of NaBH₄ was added dropwise. After reacting for 4 h, a pale yellow solution was obtained. This solution was precipitated with methanol to form a fine yellow powder, which was purified by repeated washing with methanol and then dried.

[0075] (2) Preparation of copper (111) support: 50 mg of copper nitrate and 100 mg of vitamin C were dissolved in deionized water and mixed thoroughly. Then, 100 mg of hexamethylenetetramine (HMTA) and 100 mg of cetyltrimethylammonium bromide (CTAB) were added to the solution and stirred for 3 h in an oil bath at 80 °C. The product copper (111) support was obtained by washing.

[0076] (3) Platinum clusters were loaded onto graphene nanosheet substrates at room temperature: 1 mg of platinum clusters were dispersed in ethanol, 8 mg of copper support was added and mixed thoroughly, and then 16 mg of graphene nanosheet substrate was added for loading. After thorough stirring, ferric chloride solution was added to etch the copper support. After the reaction was complete, the mixture was allowed to stand for 2 hours for aging. After aging, the resulting solution was centrifuged and washed several times, and then dried in an oven at 80°C to obtain the graphene-supported platinum monolayer catalyst.

[0077] Example 2

[0078] This embodiment provides a method for loading a palladium monolayer on a graphene substrate, the specific process of which includes:

[0079] (1) Preparation of palladium clusters Pd using mature preparation technology 13-17 (TBBT) 18-22 0.2 mmol of palladium(II) acetate and 0.4 mmol of tetraoctylammonium bromide (TOAB) were mixed and dissolved in 15 mL of tetrahydrofuran (THF). After stirring for 20 min, 0.2 mmol of 4-tert-butylthiophenol was added to the orange solution, and the mixture was stirred for another 30 min. Then, 3 mmol of NaBH4 ice-water solution was added dropwise to the mixture to reduce the Pd-thiol complex to nanoclusters. After 2 h of reaction, a black precipitate gradually formed in the solution. Finally, the black precipitate was washed four times with methanol and then extracted with dichloromethane to obtain palladium nanoclusters.

[0080] (2) Preparation of copper (111) support: 50 mg of copper nitrate and 100 mg of vitamin C were dissolved in deionized water and mixed thoroughly. Then, 100 mg of hexamethylenetetramine (HMTA) and 100 mg of cetyltrimethylammonium bromide (CTAB) were added to the solution and stirred for 3 h in an oil bath at 80 °C. The product copper (111) support was obtained by washing.

[0081] (3) At room temperature, palladium clusters were loaded onto a graphene nanosheet substrate: 1 mg of palladium clusters were dispersed in ethanol, 8 mg of copper support was added and mixed thoroughly, and then 16 mg of graphene nanosheet substrate was added for loading. After thorough stirring, excess nitric acid was added to etch the copper support. After the reaction was complete, the mixture was allowed to stand for 4 hours for aging. After aging, the resulting solution was centrifuged and washed several times, and then dried in an oven at 80°C to obtain the graphene-supported palladium monolayer catalyst.

[0082] Example 3

[0083] This embodiment provides a method for loading a palladium-silver single-atom layer on a graphene substrate, specifically including:

[0084] (1) Preparation of palladium-silver clusters using mature technology: 26.5 mg silver nitrate, 2 mg palladium chloride, 39.6 mg adamantane thiol, 182.6 mg triphenylphosphine, and 4 mg tetraphenylphosphine bromide were dissolved together in a mixed solvent of 3.52 ml methanol and 12 ml dichloromethane. After five minutes, freshly prepared sodium borohydride aqueous solution (11 mg dissolved in 1 mL ice water) was added dropwise with stirring. The reaction was aged under ambient conditions for 2 hours. After the reaction was completed, a solid powder was precipitated with methanol, purified by repeated washing with methanol, and then dried.

[0085] (2) Preparation of copper (111) support: 50 mg of copper nitrate and 100 mg of vitamin C were dissolved in deionized water and mixed thoroughly. Then, 100 mg of hexamethylenetetramine (HMTA) and 100 mg of cetyltrimethylammonium bromide (CTAB) were added to the solution and stirred for 3 h in an oil bath at 80 °C. The product copper (111) support was obtained by washing.

[0086] (3) At room temperature, palladium-silver clusters were loaded onto graphene nanosheet substrates: 1 mg of palladium-silver clusters were dispersed in ethanol, 8 mg of copper support was added and mixed thoroughly, and then 16 mg of graphene nanosheet substrate was added for loading. After thorough stirring, excess nitric acid was added to etch the copper support. After the reaction was complete, the mixture was allowed to stand for 6 hours for aging. After aging, the resulting solution was centrifuged and washed several times, and then dried in an oven at 80°C to obtain the graphene-supported palladium-silver monolayer catalyst.

[0087] In summary, this invention provides a method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst, comprising: uniformly dispersing noble metal nanoclusters and a metal single-crystal support in a solvent to obtain a first mixed solution; adding a two-dimensional material to the first mixed solution to obtain a second mixed solution; adding an etchant to the second mixed solution, and subjecting the process to an etching reaction and static aging to obtain the two-dimensional material-supported single-atom-layer noble metal catalyst. This preparation method does not impose strict limitations on the type and structure of the metal clusters and two-dimensional materials, exhibiting high versatility and enabling large-scale, orderly production under mild conditions. This method is of extraordinary significance for the further development of two-dimensional metal nanomaterials.

[0088] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst, characterized in that, include: The noble metal nanoclusters and the metal single crystal carrier are uniformly dispersed in a solvent to obtain the first mixed solution; A two-dimensional material is added to the first mixed solution to obtain a second mixed solution; An etchant was added to the second mixed solution, and after etching and aging, a two-dimensional material-supported monolayer noble metal catalyst was obtained. The method for preparing the noble metal nanoclusters includes: The noble metal salt and ligand molecules are dissolved in the reaction solvent to obtain a complex solution; A reducing agent was added dropwise to the complex solution to obtain the noble metal nanoclusters; The metal single crystal carrier is copper (111); the two-dimensional material is selected from one or more of graphene, molybdenum disulfide, and MXene. The etching agent is selected from one or more of nitric acid and ferric chloride solution.

2. The method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst according to claim 1, characterized in that, The mass ratio of the noble metal nanoclusters, the metal single crystal carrier and the two-dimensional material is 1:(6-10):(12-20).

3. The method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst according to claim 1, characterized in that, The solvent is selected from one or more of ethanol, methanol, and dichloromethane.

4. The method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst according to claim 1, characterized in that, The noble metal salt is selected from one or more of chloroplatinic acid, palladium acetate, and silver nitrate; the ligand molecule is selected from one or more of L-reduced glutathione, poly(N-vinyl-2-pyrrolidone), and 4-tert-butylthiophenol; the reducing agent is sodium borohydride; and the reaction solvent is selected from one or more of water, ethanol, and tetrahydrofuran.

5. The method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst according to claim 1, characterized in that, The method for preparing the metal single crystal carrier includes: The metal salt and vitamin C are dissolved in water to obtain a reaction solution; Hexamethylenetetramine and cetyltrimethylammonium bromide were added to the reaction solution, and the mixture was heated and washed to obtain the metal single crystal support.

6. The method for preparing a two-dimensional material-supported single-atom-layer noble metal catalyst according to claim 5, characterized in that, The heating reaction is carried out at a temperature of 60-80℃ for 3-5 hours.

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