AuPd alloy nanowire, preparation method and application thereof

Abstract

The application discloses AuPd alloy nanowires and a preparation method and application thereof, and the preparation method comprises the following steps: cutting a glass slide into a square piece and then cleaning; preparing an oil phase in a reaction system; preparing a precursor solution as an aqueous phase in the reaction system; placing the glass slide into a cylindrical vial for standby; taking the solution as the oil phase and adding into the vial, then adding the precursor solution to form an oil-water two-phase reaction system, and standing for reaction; extracting the organic phase, transferring the product to the glass slide, then extracting the aqueous solution, loading the prepared product to the glass slide, cleaning, drying, and finally preparing the AuPd alloy nanowires loaded on the glass slide. The AuPd nanowires with high length-diameter ratio, narrow diameter and uniform distribution are prepared by a simple and efficient oil-water interface synthesis method, and the AuPd nanowires are used as a catalyst to exhibit excellent photocatalytic activity and stability in a benzyl alcohol photocatalytic aerobic oxidation reaction.

Description

Technical Field

[0001] This invention belongs to the field of bimetallic nanomaterials technology, specifically relating to an AuPd alloy nanowire, its preparation method, and its application. Background Technology

[0002] Photocatalysis is a process that uses light energy to excite a catalyst and promote a chemical reaction. Compared to traditional thermocatalysis, photocatalysis utilizes light energy as its excitation energy source, resulting in higher energy efficiency. Photocatalysis typically improves reaction selectivity, leading to products with more specific chemical structures and reducing the formation of byproducts. The catalytic oxidation of benzyl alcohol is an important organic synthesis reaction, usually achieved through the action of a catalyst to increase reaction rate and selectivity. The benzaldehyde produced in this process is an important intermediate widely used in the preparation of fragrances, pharmaceuticals, and chemicals. Commonly used catalysts in the oxidation of benzyl alcohol include metal oxides, metal complexes, and transition metal catalysts. These catalysts promote the reaction of oxygen molecules with benzyl alcohol, oxidizing benzyl alcohol to benzaldehyde.

[0003] Pd exhibits high catalytic activity, effectively promoting the oxidation of benzyl alcohol and increasing the reaction rate. However, Pd catalysts are susceptible to poisoning during the reaction, leading to deactivation. An effective method is to combine Pd with other metals in alloy form. Alloy nanomaterials can enhance catalytic activity, selectivity, and stability through intermetallic electronic and geometric effects. They may also improve resistance to poisoning and extend catalyst lifespan.

[0004] Among them, AuPd nanomaterials have attracted much attention due to their excellent catalytic performance, photosensitivity, and stability. Some existing technologies first synthesize Mxene-TiO2@g-C3N4 supports through calcination and hydrothermal synthesis, and then use impregnation reduction method to synthesize supported PdAu alloys.

[0005] However, the method for preparing AuPd nanomaterials requires the use of a support and involves multiple steps, making it relatively complex. Therefore, it is necessary to develop a milder method to prepare AuPd nanomaterials with high specific surface area and high catalytic activity. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes an AuPd alloy nanowire, its preparation method, and its application. AuPd nanowires with high aspect ratio, narrow diameter, and uniform distribution are prepared through a simple and efficient oil-water interface synthesis method. These nanowires exhibit excellent photocatalytic activity and stability in the photocatalytic aerobic oxidation reaction of benzyl alcohol.

[0007] This invention is achieved through the following technical solution:

[0008] A method for preparing AuPd alloy nanowires includes the following steps:

[0009] Step 1: Cut the glass slide into squares, soak them in the mixed solution, and then clean them with anhydrous ethanol. Set aside.

[0010] Step 2: Weigh 1-naphthol and add it to chloroform to prepare a 1-naphthol solution, which will be used as the oil phase in the reaction system for later use.

[0011] Step 3: Weigh the Pd precursor and Au precursor and add them to distilled water to prepare a precursor solution, which will be used as the aqueous phase in the reaction system for later use.

[0012] Step 4: Place the glass slide from Step 1 into the cylindrical vial and set aside.

[0013] Step 5: Take the 1-naphthol solution from Step 2 and add it to the vial from Step 4. Then add the precursor solution from Step 3 to form an oil-water two-phase reaction system and let it stand to react.

[0014] Step 6: Slowly extract the organic phase and transfer the product to the glass slide from Step 4. Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat several times, and then air dry naturally to prepare AuPd alloy nanowires loaded on the glass slide.

[0015] Furthermore, in step one, the size of the block is 1cm × 1cm.

[0016] Furthermore, the mixed solution in step one includes hydrogen peroxide and concentrated sulfuric acid, wherein the volume ratio of hydrogen peroxide to concentrated sulfuric acid is 1:1.

[0017] Furthermore, the concentration of 1-naphthol in step two is 10-50 mM.

[0018] Furthermore, in step three, the Pd precursor is Na2PdCl4, with a concentration of 1.2-3.8 mM in the aqueous phase; the Au precursor is HAuCl4, with a concentration of 1.2-3.8 mM in the aqueous phase.

[0019] Furthermore, in step four, the diameter of the cylindrical vial is 2.1~2.3cm.

[0020] Furthermore, in step five, the reaction is allowed to stand for 72 hours, and the reaction temperature is 10-40℃.

[0021] The present invention also provides an AuPd alloy nanowire, which is prepared by the above preparation method. The nanowire has a diameter of 3.9~4.1 nm and a length of 349~251 nm.

[0022] This invention also provides an application of AuPd alloy nanowires in photocatalysis, specifically in the photocatalytic aerobic oxidation of benzyl alcohol to benzaldehyde. The process involves adding benzyl alcohol and anhydrous K₂CO₃ to 5 mL of distilled water to achieve final molar concentrations of 25 mM and 75 mM, respectively. After complete dissolution, 5 mg of AuPd alloy nanowires are added and uniformly dispersed in the solution. The reaction is carried out at 30°C under a 0.2 MPa O₂ atmosphere and irradiated by a xenon lamp (300 W power, 420 nm wavelength). Samples are taken at different time points, quenched with dilute hydrochloric acid, extracted three times with ethyl acetate, dried with anhydrous Na₂SO₄, and analyzed using gas chromatography-mass spectrometry (GC-MS).

[0023] The beneficial effects of this invention are as follows:

[0024] 1) The present invention uses an oil-water interface synthesis method that does not require seeds, surfactants, high temperature and high pressure and other strict reaction conditions. It is simple to operate and has low energy consumption.

[0025] 2) The AuPd alloy nanowires prepared by this invention have high specific surface area, high photocatalytic activity and stability. Attached Figure Description

[0026] Figure 1 This is a 50,000x magnified SEM image of the AuPd alloy nanowires prepared in Example 2 of this invention.

[0027] Figure 2 This is a 200,000x magnified SEM image of the AuPd alloy nanowires prepared in Example 2 of this invention.

[0028] Figure 3 This is a TEM image of the AuPd alloy nanowires prepared in Example 2 of the present invention;

[0029] Figure 4 The image shows an HRTEM image of the AuPd alloy nanowires prepared in Example 2 of this invention.

[0030] Figure 5 The above are HAADF-STEM and elemental mapping images of the AuPd alloy nanowires prepared in Example 2 of this invention.

[0031] Figure 6 The image shows the XRD pattern of the AuPd alloy nanowires prepared in Example 2 of this invention.

[0032] Figure 7 The graphs show the changes in the oxidation of benzyl alcohol by AuPd alloy nanowires prepared in Example 2 of this invention over time under light and dark conditions, respectively.

[0033] Figure 8The conversion rate and selectivity of the AuPd alloy nanowires prepared in Example 2 of this invention for photocatalytic oxidation of benzyl alcohol after 5 cycles are shown. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0035] Example 1:

[0036] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol for later use.

[0037] 2) Weigh a certain amount of 1-naphthol and add it to chloroform to prepare a 20 mM 1-naphthol solution, which will be used as the oil phase in the reaction system;

[0038] 3) Weigh a certain amount of Na2PdCl4 and HAuCl4 and add them to distilled water to prepare a precursor solution of a certain concentration, which is used as the aqueous phase in the reaction system; the molar concentrations of Na2PdCl4 and HAuCl4 in the aqueous phase solution are 3.8 mM and 1.2 mM, respectively.

[0039] 4) Place the glass slide from step 1) into a cylindrical vial with a diameter of approximately 2.2 cm;

[0040] 5) Take 4 mL of the 1-naphthol solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor aqueous solution from step 3) to form an oil-water two-phase reaction system. Let it stand at 40°C for 72 h.

[0041] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide from step 4). Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat 3 times, and then air dry to prepare AuPd alloy nanowires loaded on the glass slide.

[0042] Example 2:

[0043] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol for later use.

[0044] 2) Weigh a certain amount of 1-naphthol and add it to chloroform to prepare a 20 mM 1-naphthol solution, which will be used as the oil phase in the reaction system;

[0045] 3) Weigh a certain amount of Na2PdCl4 and HAuCl4 and add them to distilled water to prepare a precursor solution of a certain concentration, which is used as the aqueous phase in the reaction system; the molar concentrations of Na2PdCl4 and HAuCl4 in the aqueous phase solution are 2.5 mM and 2.5 mM, respectively.

[0046] 4) Place the glass slide from step 1) into a cylindrical vial with a diameter of approximately 2.2 cm;

[0047] 5) Take 4 mL of the 1-naphthol solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor aqueous solution from step 3) to form an oil-water two-phase reaction system. Let it stand at 40°C for 72 h.

[0048] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide from step 4). Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat 3 times, and then air dry to prepare AuPd alloy nanowires loaded on the glass slide.

[0049] SEM images of the AuPd nanowires prepared in this invention are shown below. Figure 1 and Figure 2 As shown in the figure, the morphology of the products is relatively uniform, all being nanowire structures. From the TEM image (… Figure 3 The nanowires were measured to have a diameter of approximately 4.0 nm and a length of approximately 350 nm, indicating a narrow particle size and a large aspect ratio. From the HRTEM images (…),… Figure 4 The lattice spacing was measured to be 0.225 nm, which is between that of Pd and Au, indicating that it is an alloy structure. The AuPd alloy nanowires prepared in this invention exhibit many crystal defects (…). Figure 4 (elliptical dashed lines), these defects can effectively serve as catalytic active sites. From the elemental mapping diagram ( Figure 5 As can be seen, Pd and Au elements are uniformly distributed throughout the nanowire region, confirming its alloy structure. This is further supported by its X-ray diffraction (XRD) pattern. Figure 6 It can be seen that the AuPd nanowires have a face-centered cubic structure, and the peak position is between that of pure Pd and Au. No other impurity peaks appear, which further proves that it has an alloy structure and high purity.

[0050] Example 3:

[0051] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol for later use.

[0052] 2) Weigh a certain amount of 1-naphthol and add it to chloroform to prepare a 20 mM 1-naphthol solution, which will be used as the oil phase in the reaction system;

[0053] 3) Weigh a certain amount of Na2PdCl4 and HAuCl4 and add them to distilled water to prepare a precursor solution of a certain concentration, which is used as the aqueous phase in the reaction system; the molar concentrations of Na2PdCl4 and HAuCl4 in the aqueous phase solution are 1.2 mM and 3.8 mM, respectively.

[0054] 4) Place the glass slide from step 1) into a cylindrical vial with a diameter of approximately 2.2 cm;

[0055] 5) Take 4 mL of the 1-naphthol solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor aqueous solution from step 3) to form an oil-water two-phase reaction system. Let it stand at 40°C for 72 h.

[0056] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide from step 4). Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat 3 times, and then air dry to prepare AuPd alloy nanowires loaded on the glass slide.

[0057] Example 4:

[0058] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol for later use.

[0059] 2) Weigh a certain amount of 1-naphthol and add it to chloroform to prepare a 30 mM 1-naphthol solution, which will be used as the oil phase in the reaction system;

[0060] 3) Weigh a certain amount of Na2PdCl4 and HAuCl4 and add them to distilled water to prepare a precursor solution of a certain concentration, which is used as the aqueous phase in the reaction system; the molar concentrations of Na2PdCl4 and HAuCl4 in the aqueous phase solution are 2.5 mM and 2.5 mM, respectively.

[0061] 4) Place the glass slide from step 1) into a cylindrical vial with a diameter of approximately 2.2 cm;

[0062] 5) Take 4 mL of the 1-naphthol solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor aqueous solution from step 3) to form an oil-water two-phase reaction system. Let it stand at 40°C for 72 h.

[0063] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide from step 4). Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat 3 times, and then air dry to prepare AuPd alloy nanowires loaded on the glass slide.

[0064] Example 5:

[0065] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol for later use.

[0066] 2) Weigh a certain amount of 1-naphthol and add it to chloroform to prepare a 50 mM 1-naphthol solution, which will be used as the oil phase in the reaction system;

[0067] 3) Weigh a certain amount of Na2PdCl4 and HAuCl4 and add them to distilled water to prepare a precursor solution of a certain concentration, which is used as the aqueous phase in the reaction system; the molar concentrations of Na2PdCl4 and HAuCl4 in the aqueous phase solution are 2.5 mM and 2.5 mM, respectively.

[0068] 4) Place the glass slide from step 1) into a cylindrical vial with a diameter of approximately 2.2 cm;

[0069] 5) Take 4 mL of the 1-naphthol solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor aqueous solution from step 3) to form an oil-water two-phase reaction system. Let it stand at 40°C for 72 h.

[0070] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide from step 4). Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat 3 times, and then air dry to prepare AuPd alloy nanowires loaded on the glass slide.

[0071] Example 6:

[0072] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol for later use.

[0073] 2) Weigh a certain amount of 1-naphthol and add it to chloroform to prepare a 10 mM 1-naphthol solution, which will be used as the oil phase in the reaction system;

[0074] 3) Weigh a certain amount of Na2PdCl4 and HAuCl4 and add them to distilled water to prepare a precursor solution of a certain concentration, which is used as the aqueous phase in the reaction system; the molar concentrations of Na2PdCl4 and HAuCl4 in the aqueous phase solution are 2.5 mM and 2.5 mM, respectively.

[0075] 4) Place the glass slide from step 1) into a cylindrical vial with a diameter of approximately 2.2 cm;

[0076] 5) Take 4 mL of the 1-naphthol solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor aqueous solution from step 3) to form an oil-water two-phase reaction system. Let the reaction stand at 25°C for 72 h.

[0077] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide from step 4). Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat 3 times, and then air dry to prepare AuPd alloy nanowires loaded on the glass slide.

[0078] Example 7:

[0079] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol for later use.

[0080] 2) Weigh a certain amount of 1-naphthol and add it to chloroform to prepare a 20 mM 1-naphthol solution, which will be used as the oil phase in the reaction system;

[0081] 3) Weigh a certain amount of Na2PdCl4 and HAuCl4 and add them to distilled water to prepare a precursor solution of a certain concentration, which is used as the aqueous phase in the reaction system; the molar concentrations of Na2PdCl4 and HAuCl4 in the aqueous phase solution are 2.5 mM and 2.5 mM, respectively.

[0082] 4) Place the glass slide from step 1) into a cylindrical vial with a diameter of approximately 2.2 cm;

[0083] 5) Take 4 mL of the 1-naphthol solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor aqueous solution from step 3) to form an oil-water two-phase reaction system. Let it stand at 10°C for 72 h to react.

[0084] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide from step 4). Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat 3 times, and then air dry to prepare AuPd alloy nanowires loaded on the glass slide.

[0085] This invention also provides an application of AuPd alloy nanowires in photocatalysis, specifically in the photocatalytic aerobic oxidation of benzyl alcohol to benzaldehyde. The process involves adding benzyl alcohol and anhydrous K₂CO₃ to 5 mL of distilled water to achieve final molar concentrations of 25 mM and 75 mM, respectively. After complete dissolution, 5 mg of AuPd alloy nanowires are added and uniformly dispersed in the solution. The reaction is carried out at 30°C under a 0.2 MPa O₂ atmosphere and irradiated by a xenon lamp (300 W power, 420 nm wavelength). Samples are taken at different time points, quenched with dilute hydrochloric acid, extracted three times with ethyl acetate, dried with anhydrous Na₂SO₄, and analyzed using gas chromatography-mass spectrometry (GC-MS).

[0086] In the photocatalytic aerobic oxidation of benzyl alcohol, the reaction was carried out at 30℃ under a 0.2 MPa O2 atmosphere and irradiated by a xenon lamp for 40 min, achieving a benzyl alcohol conversion rate as high as 97.73%; while under dark conditions, the conversion rate of benzyl alcohol was only 69.23% after 40 min. Figure 7 After five photocatalytic cycles, the conversion rate was 93.03% and the selectivity was 100%. Figure 8 This indicates that the catalyst possesses excellent photocatalytic activity and stability.

[0087] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.

Claims

1. A method for preparing AuPd alloy nanowires, characterized in that: Includes the following steps: Step 1: Cut the glass slide into squares, soak them in the mixed solution, and then clean them with anhydrous ethanol. Set aside. Step 2: Weigh 1-naphthol and add it to chloroform to prepare a 1-naphthol solution, which will be used as the oil phase in the reaction system for later use. Step 3: Weigh the Pd precursor and Au precursor and add them to distilled water to prepare a precursor solution, which will be used as the aqueous phase in the reaction system for later use. Step 4: Place the glass slide from Step 1 into the cylindrical vial and set aside. Step 5: Take the 1-naphthol solution from Step 2 and add it to the vial from Step 4. Then add the precursor solution from Step 3 to form an oil-water two-phase reaction system and let it stand to react. Step 6: Slowly extract the organic phase and transfer the product to the glass slide from Step 4. Then extract the aqueous solution and load the obtained product onto the glass slide. Soak in ethanol, extract, repeat several times, and then air dry naturally to prepare AuPd alloy nanowires loaded on the glass slide.

2. The method for preparing AuPd alloy nanowires according to claim 1, characterized in that: In step one, the size of the square is 1cm × 1cm.

3. The method for preparing AuPd alloy nanowires according to claim 1, characterized in that: The mixed solution in step one includes hydrogen peroxide and concentrated sulfuric acid, with a volume ratio of 1:

1.

4. The method for preparing AuPd alloy nanowires according to claim 1, characterized in that: The concentration of 1-naphthol in step two is 10-50 mM.

5. The method for preparing AuPd alloy nanowires according to claim 1, characterized in that: In step three, the Pd precursor is Na2PdCl4, with a concentration of 1.2-3.8 mM in the aqueous phase; the Au precursor is HAuCl4, with a concentration of 1.2-3.8 mM in the aqueous phase.

6. The method for preparing AuPd alloy nanowires according to claim 1, characterized in that: In step four, the diameter of the cylindrical vial is 2.1~2.3cm.

7. The method for preparing AuPd alloy nanowires according to claim 1, characterized in that: In step five, the reaction is allowed to stand for 72 hours, and the reaction temperature is 10-40℃.

8. An AuPd alloy nanowire, characterized in that: The nanowires are prepared by the preparation method described in any one of claims 1 to 7, and have a diameter of 3.9 to 4.1 nm and a length of 349 to 251 nm.

9. The application of the AuPd alloy nanowire according to claim 8 in photocatalysis, characterized in that: The photocatalytic aerobic oxidation of benzyl alcohol to benzaldehyde was applied to this reaction. Specifically, benzyl alcohol and anhydrous K2CO3 were added to 5 mL of distilled water to achieve final molar concentrations of 25 mM and 75 mM, respectively. After complete dissolution, 5 mg of AuPd alloy nanowires were added and uniformly dispersed in the solution. The reaction was carried out at 30 °C under a 0.2 MPa O2 atmosphere and irradiated by a xenon lamp with a power of 300 W and a wavelength of 420 nm. Samples were taken at different time points, quenched with dilute hydrochloric acid, extracted three times with ethyl acetate, and dried with anhydrous Na2SO4. The products were analyzed using gas chromatography-mass spectrometry (GC-MS).

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