Preparation method of two-dimensional AuAg alloy nanosheet catalyst with dendritic pore structure
By combining the coordination chemical bonds between cationic surfactants and metal precursors with co-reducing agents, a two-dimensional AuAg alloy nanosheet catalyst with a dendritic pore structure was successfully prepared, solving the problem of difficult control of morphology and composition in the prior art and improving the performance and economy of the catalyst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SICHUAN UNIV
- Filing Date
- 2026-04-03
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies cannot simultaneously achieve a controllable dendritic channel structure and uniform alloy composition in two-dimensional AuAg alloy nanosheets, which limits the improvement of catalyst performance.
Two-dimensional AuAg alloy nanosheet catalysts with a dendritic pore structure were prepared by using the coordination chemical interaction between the cationic surfactant N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride and the metal precursors chloroauric acid and silver nitrate, combined with the co-reducing agent L-ascorbic acid, via a simple liquid-phase method.
Two-dimensional AuAg alloy nanosheet catalysts with high specific surface area and abundant active sites were achieved, which optimized the transport and diffusion of reaction molecules, improved metal utilization and catalytic activity, and reduced preparation costs.
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Figure CN122298401A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for preparing a two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure. Background Technology
[0002] Noble metal and alloy nanomaterials, due to their unique physicochemical properties, have shown broad application prospects in heterogeneous catalysis, electrocatalysis, energy conversion, and storage. The performance of a catalyst is closely related to its morphology, size, composition, and microstructure. Among them, two-dimensional nanostructures, especially nanosheets with abundant pores, have attracted much attention due to their high specific surface area, abundant low-coordination atomic sites, and excellent mass transport capabilities. Compared with zero-dimensional or one-dimensional structures, two-dimensional nanosheets can provide a larger active surface area and more accessible active sites, thereby significantly improving catalytic efficiency. Furthermore, the presence of dendritic pore structures can not only further increase the density of active sites but also create a favorable nano-confined environment, modulating the adsorption behavior of reaction intermediates and optimizing reaction pathways.
[0003] Gold (Au) and silver (Ag), as important noble metal components, exhibit excellent performance in catalysis when their alloy (AuAg) is formed. However, single metals often suffer from insufficient activity or selectivity. By alloying Au and Ag, the electronic structure (i.e., ligand effect) and geometric structure (i.e., strain effect) of the catalyst can be tuned, thereby optimizing its adsorption energy for reactants and intermediates and achieving a synergistic enhancement of catalytic activity and selectivity. Therefore, developing AuAg alloy nanomaterials with specific morphologies and abundant pore structures has significant research value and practical implications.
[0004] Currently, methods for preparing AuAg alloy nanomaterials mainly include seed growth, electrochemical deposition, and high-temperature pyrolysis. However, these methods typically suffer from cumbersome procedures, demanding reaction conditions (such as requiring high temperature, high pressure, or specific templates), and difficulties in precisely controlling morphology and composition. In particular, simultaneously achieving two-dimensional anisotropic growth, controllable dendritic channel structures, and uniform alloy composition remains a challenge in this field. Existing technologies struggle to obtain two-dimensional AuAg alloy nanosheets with large specific surface areas, abundant and open dendritic channels, and highly active exposed crystal faces, limiting further improvements in the performance of AuAg alloy catalysts and in-depth research into their structure-activity relationships.
[0005] Therefore, developing a simple, mild, and controllable synthesis strategy for preparing two-dimensional AuAg alloy nanosheets with unique dendritic channel structures is of great significance for promoting the development of high-performance metal catalysts. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a simple, mild, and controllable method for preparing a two-dimensional AuAg alloy nanosheet catalyst with a dendritic pore structure.
[0007] To achieve the above objectives, the present invention provides a method for preparing a two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure as follows: N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride is dissolved in deionized water by heating, shaken well, and cooled to room temperature. Then, chloroauric acid and silver nitrate are added. The resulting reaction solution is allowed to stand at 25-35°C for 20-40 minutes, and then L-ascorbic acid is added. The reaction is allowed to stand at 25-35°C for 5-7 hours. After the reaction is completed, the catalyst is centrifuged and washed to obtain the two-dimensional AuAg alloy nanosheet catalyst.
[0008] Preferably, in the above preparation method, the content of N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride in the reaction solution is 0.07 to 0.11 mg / mL.
[0009] Preferably, in the above preparation method, N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride is dissolved in deionized water by heating at 50-80 °C.
[0010] Preferably, in the above preparation method, the concentration of chloroauric acid in the reaction solution is 0.80–1.0 mmol / L.
[0011] Preferably, in the above preparation method, the concentration of silver nitrate in the reaction solution is 0.10–0.12 mmol / L.
[0012] Preferably, in the above preparation method, the amount of L-ascorbic acid added is 120 to 150 times the total amount of chloroauric acid and silver nitrate.
[0013] Preferably, in the above preparation method, after the reaction is completed, the mixture is centrifuged and washed with anhydrous ethanol, and then vacuum dried at 50–60 °C.
[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0015] 1. This invention utilizes the coordination chemical bond interaction between the cationic surfactant N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride and the metal precursors chloroauric acid and silver nitrate to achieve the co-assembly of the surfactant-metal precursor. Subsequently, a co-reducing agent is introduced for co-reduction, successfully preparing a two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure. This functional amphiphilic surfactant can guide the formation of an asymmetric two-dimensional nanometal nanostructure. Furthermore, this preparation method simplifies the catalyst preparation process, reduces the catalyst preparation cost, and the synthesis reaction is simple, easy to operate, and suitable for large-scale preparation.
[0016] 2. The two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure of this invention exhibits several advantages in terms of structure and composition: Structurally, on the one hand, the mesoporous structure increases the number of active sites and the proportion of unsaturated sites, improving metal utilization efficiency and thus reducing the cost of catalytic reactions; on the other hand, the two-dimensional dendritic channel structure, compared with traditional spherical channels, significantly optimizes the accessibility of reactant molecules, maximizing the utilization efficiency of the channels, which is beneficial for the efficient transport and diffusion of reactants, intermediates, and products, and greatly improves the utilization rate of metals. Compositionally, Au and Ag form an alloy, and the electronic structure can be adjusted through ligands and strain effects, which is expected to optimize its intrinsic activity and selectivity in a variety of catalytic reactions.
[0017] 3. This invention achieves the preparation of AuAg alloy nanosheet catalysts with a two-dimensional rich dendritic channel structure through a simple liquid phase method, providing a new strategy for preparing high-performance noble metal alloy nanocatalysts under mild conditions. The prepared catalyst, with its unique structural and component advantages, can significantly improve metal utilization and reduce raw material costs, and has broad application prospects in the field of catalysis. Attached Figure Description
[0018] Figure 1 The images shown are transmission electron microscopy (TEM) images and partial magnification images (b) of the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure prepared in Example 1 (a).
[0019] Figure 2 The images shown are transmission electron microscope (TEM) image (a), high-magnification TEM image (b, c), and high-resolution TEM image (d) of the two-dimensional AuAg alloy nanosheet catalyst with dendritic channel structure prepared in Example 2.
[0020] Figure 3 Transmission electron microscopy (TEM) images of the two-dimensional Au nanosheet catalysts (a, b) prepared in Comparative Example 1 and the Ag nanoparticle catalysts (c, d) prepared in Comparative Example 2.
[0021] Figure 4The X-ray photoelectron spectra of the corresponding gold (a) and silver (b) elements of the two-dimensional AuAg alloy nanosheet catalyst with dendritic channel structure prepared in Example 1, the two-dimensional Au nanosheet catalyst prepared in Comparative Example 1, and the Ag nanoparticle catalyst prepared in Comparative Example 2 are shown.
[0022] Figure 5 This is the wide-angle X-ray diffraction pattern of the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure prepared in Example 1.
[0023] Figure 6 The energy dispersive X-ray spectrum (EDS) of the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure prepared in Example 1 is shown. Detailed Implementation
[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.
[0025] Example 1
[0026] At 75 °C, 2 mg of N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride was added to 20 mL of deionized water. After stirring until the solid was completely dissolved, the mixture was cooled to room temperature. Then, 2 mL of 0.010 mol / L chloroauric acid aqueous solution and 250 µL of 0.010 mol / L silver nitrate solution were added to obtain the reaction solution. The concentrations of N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride, chloroauric acid, and silver nitrate in the reaction solution were 0.0899 mg / mL, 0.90 mmol / L, and 0.11 mmol / L, respectively. The reaction solution was then allowed to stand at 30 °C for 30 minutes. Then, 10 mL of 0.053 g / mL L-ascorbic acid aqueous solution was added. The amount of L-ascorbic acid added was 134 times the total amount of chloroauric acid and silver nitrate. The mixture was gently shaken and allowed to stand at 30 °C for 6 hours. After the reaction was completed, the mixture was washed with anhydrous ethanol by centrifugation to remove N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride. The resulting solid was dried in a vacuum drying oven at 60 °C for 2 hours to obtain a two-dimensional AuAg alloy nanosheet catalyst.
[0027] Example 2
[0028] At 75 °C, 2 mg of N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride was added to 20 mL of deionized water. After stirring until the solid was completely dissolved, the mixture was cooled to room temperature. Then, 2 mL of 0.010 mol / L chloroauric acid aqueous solution and 167 µL of 0.010 mol / L silver nitrate solution were added to obtain the reaction solution. The concentrations of N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride, chloroauric acid, and silver nitrate in the reaction solution were 0.0902 mg / mL, 0.9022 mmol / L, and 0.0753 mmol / L, respectively. The reaction solution was then allowed to stand at 30 °C for 30 minutes. Then, 10 mL of 0.053 g / mL L-ascorbic acid aqueous solution was added. The amount of L-ascorbic acid added was 139 times the total amount of chloroauric acid and silver nitrate. The mixture was gently shaken and allowed to stand at 30 °C for 6 hours. After the reaction was completed, the mixture was washed with anhydrous ethanol by centrifugation to remove N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride. The resulting solid was dried in a vacuum drying oven at 60 °C for 2 hours to obtain a two-dimensional AuAg alloy nanosheet catalyst.
[0029] Comparative Example 1
[0030] In Example 1, silver nitrate was not added, and the other steps were the same as in Example 1, resulting in a two-dimensional Au nanosheet catalyst.
[0031] Comparative Example 2
[0032] At room temperature, 7.416 mL of 0.01 mol / L silver nitrate aqueous solution was placed in a beaker, and 40 mg of carbon spheres (VulcanXC-72) were added. The mixture was sonicated to ensure homogeneity. The solution was then slowly stirred at room temperature until dry. The resulting solid powder was poured into 64 mL of 10 mmol / L sodium borohydride aqueous solution and stirred for 2 hours. After the reaction was complete, the solid was washed with deionized water by centrifugation. The resulting solid was dried in a vacuum drying oven at 60 °C for 2 hours to obtain Ag nanoparticle catalyst supported on VulcanXC-72.
[0033] The catalysts obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were characterized structurally, and the results are shown in the figure. Figures 1-4 .
[0034] Depend on Figure 1 (a) As can be seen, the catalyst obtained in Example 1 has a typical two-dimensional nanosheet structure with regular sheet morphology and uniform size. Figure 1 (b) The magnified view further shows that the nanosheet surface has abundant pores, which are distributed in a dendritic pattern and radiate towards the edge of the sheet. This open pore structure is conducive to the entry and diffusion of reactant molecules.
[0035] Figure 2 The transmission electron microscopy image (a) shows that the catalyst obtained in Example 2 also has a two-dimensional nanosheet structure and is uniform in size. Figure 2 The high-magnification transmission electron microscope images (b and c) clearly show that there are abundant dendritic channels on the surface of the nanosheets. Figure 2 The high-resolution transmission electron microscope image of (d) shows a lattice spacing of 0.234 nm, corresponding to the (111) crystal plane of the AuAg alloy.
[0036] Figure 3 (a, b) are two-dimensional Au nanosheet catalysts prepared in Comparative Example 1. It can be seen that they also have two-dimensional nanosheet structures and dendritic channels, but their surface structures are relatively simple compared with Examples 1-2. Figure 3 (c, d) are Ag nanoparticle catalysts prepared in Comparative Example 2. It can be seen that the products are granular, randomly distributed, and have a uniform overall size of about 5 nm, without two-dimensional sheet-like morphology.
[0037] Figure 4 (a) shows that, compared to the pure Au nanosheets of Comparative Example 1, the Au 4f peak in the AuAg alloy nanosheets of Example 1 shifts toward the direction of higher binding energy; Figure 4 (b) shows that, compared to the pure Ag nanoparticles of Comparative Example 2, the Ag 3d peak in the AuAg alloy nanosheets of Example 1 shifts towards a lower binding energy. This shift in binding energy demonstrates that electronic interactions occurred between Au and Ag, forming an alloy structure rather than a simple physical mixture, further confirming the successful preparation of AuAg alloy nanosheets by the method of the present invention.
[0038] Figure 5 The catalyst of Example 1 showed XRD signals corresponding to face-centered cubic (fcc) crystals, which can be attributed to the (111), (200), (220), (311), and (222) crystal planes of the face-centered cubic crystal, respectively, indicating that the catalyst exhibits a polycrystalline structure.
[0039] Figure 6 The EDS spectrum of the catalyst in Example 1 showed that it contained Au and Ag elements, i.e., the successful doping of Ag elements, which further confirmed the successful synthesis of AuAg alloy.
[0040] comprehensive Figures 1-6 Analysis shows that the method of this invention successfully prepared AuAg alloy nanosheet catalysts with two-dimensional sheet morphology and abundant dendritic channels. This unique structural feature and alloy composition endow the catalyst with high specific surface area, abundant active sites, excellent mass transfer performance, and tunable electronic structure, making it promising for broad applications in the field of catalysis.
[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Any modifications, alterations, or equivalent transformations made to the above embodiments based on the content of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A method for preparing a two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure, characterized in that: N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride was dissolved in deionized water by heating, shaken well, and cooled to room temperature. Then, chloroauric acid and silver nitrate were added. The resulting reaction solution was allowed to stand at 25-35°C for 20-40 minutes. L-ascorbic acid was then added, and the reaction was allowed to stand at 25-35°C for 5-7 hours. After the reaction was completed, the solution was centrifuged and washed to obtain a two-dimensional AuAg alloy nanosheet catalyst with a dendritic pore structure.
2. The method for preparing the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure according to claim 1, characterized in that: The content of N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride in the reaction solution is 0.07–0.11 mg / mL.
3. The method for preparing a two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure according to claim 1 or 2, characterized in that: N-(2-mercaptoethyl)-N,N-dimethyloctadecyl-1-ammonium chloride was dissolved in deionized water by heating at 50–80 °C.
4. The method for preparing the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure according to claim 1, characterized in that: The concentration of chloroauric acid in the reaction solution is 0.80–1.0 mmol / L.
5. The method for preparing the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure according to claim 1, characterized in that: The concentration of silver nitrate in the reaction solution is 0.10–0.12 mmol / L.
6. The method for preparing the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure according to claim 1, characterized in that: The amount of L-ascorbic acid added is 120 to 150 times the total amount of chloroauric acid and silver nitrate.
7. The method for preparing the two-dimensional AuAg alloy nanosheet catalyst with a dendritic channel structure according to claim 1, characterized in that: After the reaction is complete, the mixture is washed by centrifugation with anhydrous ethanol and dried under vacuum at 50–60 °C.