Preparation and application of a Pt-embedded pudding structure of fluorotin-niobate-tin octahedron

Abstract

The application discloses a preparation and application of a Pt-embedded pudding structure of octahedral TFN-SnO2, and relates to the technical field of nanometer materials. The preparation method comprises the following steps: mixing a niobate aqueous solution, a SnCl2 aqueous solution and hydrofluoric acid, and carrying out hydrothermal treatment to obtain TFN (tin fluoride niobate); centrifuging and washing the TFN, and then dispersing the TFN in water; adding a H2PtCl6 solution to the TFN in water, and continuously stirring the mixture; centrifuging and washing the precipitate to obtain a Pt-TFN / SnO2 composite material. The Pt-embedded pudding structure of octahedral TFN-SnO2 can be obtained without a surfactant. The obtained octahedral Pt-TFN / SnO2 composite material has good catalytic activity in the reaction of reducing nitrophenol into p-aminophenol under alkaline conditions.

Description

Technical Field

[0001] This invention belongs to the fields of inorganic nanomaterials and platinum group metal nanomaterials, specifically relating to the preparation and application of a pudding structure of Pt embedded in fluorinated tin niobate-tin oxide octahedron. Background Technology

[0002] Platinum (Pt) nanomaterials have attracted widespread attention due to their outstanding catalytic performance in carbon monoxide removal, automotive exhaust purification, novel fuel cells, and hydrogenation reactions. Platinum nanoparticles with defined crystal faces have broad applications in catalytic reactions because different crystal faces, due to variations in atomic arrangement, lead to significant changes in the adsorption and activation energies of the substrate. These surface properties play a crucial role in catalytic reactions, such as regulating the activity and selectivity of the reaction. As the size of noble metal nanoparticles decreases, the proportion of surface atoms increases rapidly, resulting in a sharp increase in specific surface area. Simultaneously, smaller particles have more edge atoms and surface defect sites, forming more atomic steps. These changes significantly increase the contact area between the catalytic substrate and the catalyst, thereby affecting catalytic activity and selectivity. Therefore, controlling the size and morphology of platinum nanoparticles helps to better understand the structure-activity relationship of catalysts.

[0003] Common methods for controlling the nanomorphology of nanomaterials include spontaneous crystal growth, the addition of surfactants, and template methods. However, these methods have certain drawbacks. For example, while materials grown using the anisotropy of the crystal itself can effectively produce one-dimensional nanostructures, this method cannot be used if the crystal itself does not possess anisotropic structural characteristics. Adding surfactants increases the cost of material synthesis and can adsorb onto the surface of catalysts, reducing catalyst activity and affecting catalytic performance. Hard template methods suffer from poor continuity, resulting in catalysts with low metal inter-linking and high cost, making mass production difficult. Summary of the Invention

[0004] To address the above shortcomings, the present invention aims to provide a low-cost and highly safe method for producing pudding-structured Pt-TFN / SnO2 materials. This method eliminates the need for surfactants while effectively controlling the morphology and particle size of the nanomaterials. Furthermore, it exhibits excellent catalytic activity in the reduction of p-nitrophenol to p-aminophenol under alkaline conditions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a pudding structure of Pt embedded in fluorotin niobate-tin oxide octahedrons involves using TFN as a structure directing agent and conducting a redox reaction between TFN and chloroplatinic acid to prepare an octahedral Pt-TFN / SnO2 material. Platinum nanoparticles are embedded within the octahedral structure of the fluorotin niobate-tin oxide. The preparation method includes the following steps:

[0007] 1) Weigh 0.2-0.3g of niobic acid and 0.06-0.09g of stannous chloride into beakers, and add 10-100mL of pure water to each beaker. Sonicate to mix the liquids. Combine the liquids in the two beakers, add 1-2mL of 47wt% hydrofluoric acid, stir magnetically for 1-2 hours, and treat with hydrothermal treatment at 180℃ for 24 hours. Centrifuge and wash to obtain fluorinated stannous niobate TFN solid (i.e., SnNbOF material).

[0008] 2) Disperse 0.2-0.3g of TFN in 100 mL of pure water, then add 430-500 μL of 0.01mol / L H2PtCl6 solution and continue stirring for 10-15 h.

[0009] 3) Pour the liquid into centrifuge tubes and centrifuge. Discard the waste liquid, then wash and centrifuge repeatedly with pure water. Dry the precipitate in a vacuum drying oven at 50~70℃ for 10~12 hours.

[0010] 4) After confirming that the product is completely dried, remove it from the vacuum drying oven to obtain Pt-TFN / SnO2 material, and grind it into powder using a mortar and pestle for collection and storage.

[0011] The interplanar spacing of Pt nanoparticles in the Pt-TFN / SnO2 with the pudding structure is 0.235 nm.

[0012] The application of the Pt-TFN / SnO2 material in the catalytic reduction of p-nitrophenol to p-aminophenol under alkaline conditions.

[0013] Furthermore, the Pt-TFN / SnO2 material was ultrasonicated with p-nitrophenol (4-NP) and then cooled to room temperature. Sodium borohydride was added at room temperature, and timing was started when the solution turned yellow. The absorbance at 399 nm was scanned using a V-5600 microscope. The supernatant was collected at regular time intervals for catalytic performance testing. It was found that the Pt-TFN / SnO2 material exhibits excellent catalytic activity for the reduction of p-nitrophenol to p-aminophenol under alkaline conditions.

[0014] This invention employs the above technical solution to prepare a pudding-structured Pt-TFN / SnO2 material by using TFN as a structure directing agent to adjust the structure and morphology. The theoretical basis is that a reducing TFN support is used to promote a redox reaction between chloroplatinic acid and the support. Platinum nanoparticles are embedded in the octahedral structure of TFN-tin dioxide. The Pt-TFN / SnO2 material can be used to test the catalytic performance of p-nitrophenol.

[0015] The beneficial effects of this invention are as follows:

[0016] 1. The obtained pudding-structured Pt-TFN / SnO2 material does not require the addition of surfactants during the experiment to obtain octahedral TFN-tin oxide.

[0017] 2. The structure of octahedral TFN-tin oxide-encapsulated Pt nanoparticles can be obtained in one step, without the need to first synthesize Pt nanoparticles and then coat them with tin oxide. Furthermore, this method can effectively control the size of Pt nanoparticles.

[0018] 3. Pt-TFN / SnO2 materials exhibit excellent catalytic activity for the reduction of p-nitrophenol to p-aminophenol under alkaline conditions.

[0019] 4. The synthesized Pt-TFN / SnO2 material has the advantages of low cost, simple operation, and safety. Attached Figure Description

[0020] Figure 1 The X-ray diffraction pattern of the TFN material obtained in Example 1;

[0021] Figure 2 The image shows a scanning electron microscope image of the TFN material obtained in Example 1.

[0022] Figure 3 This is a scanning electron microscope image of the Pt-TFN / SnO2 material obtained in Example 1;

[0023] Figure 4 This is a high-resolution transmission electron microscope image of the Pt-TFN / SnO2 material obtained in Example 1;

[0024] Figure 5 EDS image of the Pt-TFN / SnO2 material obtained in Example 1 (taken using TEM EDS, Cu element obtained from copper mesh);

[0025] Figure 6 The UV spectrum of the Pt-TFN / SnO2 obtained in Example 1 under alkaline conditions for catalytic reduction of p-nitrophenol;

[0026] Figure 7The graph shows the catalytic performance of Pt-TFN / SnO2 obtained in Example 1 on p-nitrophenol under alkaline conditions. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the embodiments and accompanying drawings. Example 1

[0028] Preparation and application of a pudding structure of Pt embedded in fluorinated tin niobate-tin oxide octahedron

[0029] 1) Preparation of Pt-TFN / SnO2 with pudding structure: Weigh 0.250 g of niobic acid and 100 mL of pure water into a 150 mL beaker, and weigh 0.070 g of SnCl2 and 20 mL of pure water into a 50 mL beaker. Sonicate to mix the solutions. Combine the liquids from the two beakers, add 2 mL of 47wt% HF solution, and stir magnetically for 1 h. Hydrothermally heat at 180℃ for 24 h to obtain solid TFN. After washing and centrifugation, add 100 mL of pure water for dispersion, then add 430 μL of 0.01mol / L H2PtCl6 solution and continue stirring for 12 h. Afterward, centrifuge again, wash the precipitate with pure water and centrifuge four times, and dry the precipitate in a 60℃ oven for 12 h. After confirming complete drying, remove the product to obtain Pt-TFN / SnO2 material, grind it into powder using a mortar and pestle, collect, dry, and store.

[0030] 2) Application of Pt-TFN / SnO2 with pudding structure: Under pH=10 conditions, 5 mg of Pt-TFN / SnO2 material was sonicated with 60 mL of 10 ppm p-nitrophenol (4-NP) and cooled to room temperature. 20 mg of sodium borohydride was added at room temperature. Timing started when the solution turned yellow. The absorbance at 399 nm was scanned using a V-5600 UV-Vis spectrophotometer. One point was taken every two minutes, and five points were taken to test the catalytic performance.

[0031] See results Figure 1-7 , Figure 1 The image shows the X-ray diffraction pattern of the TFN material obtained in Example 1. Figure 2 The image shows a scanning electron microscope image of TFN material. As can be seen from the image, TFN has an octahedral shape. Figure 3 and Figure 4The images show scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM) images of the Pt-TFN / SnO2 material, respectively. Due to the redox reaction between Sn and Pt ions, the resulting SnO2 uniformly coats the TFN surface, making the TFN surface rougher. Pt is uniformly distributed throughout the entire nano-octahedron and is not deposited on the outermost surface of the SnO2 layer. This indicates that we have successfully fabricated a pudding-structure catalyst with Pt embedded in tin oxide octahedra. Figure 4 It can be seen that the interplanar spacing of Pt nanoparticles is 0.235 nm, while that of SnO2 is 0.352 nm. Figure 5 The image shows the EDS diagram of the Pt-TFN / SnO2 material. As can be seen from the image, Pt is uniformly distributed throughout the octahedron. Figure 6 The image shows the UV spectrum of the catalytic reduction of p-nitrophenol by Pt-TFN / SnO2 under alkaline conditions. Figure 6 It can be seen that p-nitrophenol can be reduced to p-aminophenol under the action of sodium borohydride, and the rate constant for the formation of p-aminophenol is 27.38 min. -1 The selectivity is approximately 90%. Figure 7 This is a graph showing the catalytic performance of Pt-TFN / SnO2 on p-nitrophenol under alkaline conditions. (Source: [Insert graph here]) Figure 7 It can be seen that the Pt-TFN / SnO2 material exhibits good catalytic activity, causing the absorbance to decrease with increasing time. In contrast, the blank control group without added catalyst did not react, and its absorbance remained unchanged. Example 2

[0032] Preparation and application of a pudding structure of tin oxide octahedral embedded Pt

[0033] Weigh 0.250 g of niobic acid and 100 mL of pure water into a 150 mL beaker, then weigh 0.080 g of SnCl2 and 20 mL of pure water into a 50 mL beaker. Sonicate to mix the solutions. Combine the liquids from the two beakers, add 2 mL of 47 wt% HF solution, and stir magnetically for 1 h. Hydrothermally heat at 180℃ for 24 h to obtain solid TFN. After centrifugation and washing, discard the supernatant, add 100 mL of pure water to disperse, then add 450 μL of 0.01 mol / L H2PtCl6 solution and continue stirring for 12 h. After stirring, centrifuge the liquid, discard the waste liquid, wash the precipitate with pure water and centrifuge four times, then dry the precipitate in an oven (12 h, 60℃). After confirming complete drying, remove the product from the oven to obtain Pt-TFN / SnO2 material, grind it into powder using a mortar and pestle, collect, dry, and store. Example 3

[0034] Preparation and application of a pudding structure of tin oxide octahedral embedded Pt

[0035] Weigh 0.250 g of niobic acid and 100 mL of pure water into a 150 mL beaker, then weigh 0.090 g of SnCl2 and 20 mL of pure water into a 50 mL beaker. Sonicate to mix the solutions. Combine the liquids from the two beakers, add 2 mL of 47 wt% HF solution, stir magnetically for 1 h, and then hydrothermally heat at 180℃ for 24 h to obtain solid TFN. After centrifugation and washing, discard the supernatant, add 100 mL of pure water to disperse, then add 500 μL of 0.01 mol / L H2PtCl6 solution and continue stirring for 12 h. After stirring, centrifuge the liquid, discard the waste liquid, wash the precipitate with pure water and centrifuge four times, then dry the precipitate in an oven (10 h, 70℃). After confirming complete drying, remove the product from the oven to obtain Pt-TFN / SnO2 material, grind it into powder using a mortar and pestle, collect, dry, and store.

[0036] The above detailed description of the preparation and application of a pudding structure of tin oxide octahedral embedded Pt in the reference embodiments is illustrative rather than limiting. Several embodiments can be listed according to the defined scope. Therefore, changes and modifications without departing from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A method for producing a Pt-embedded pudding structure of a fluorotin-oxide tin octahedron, characterized by, Octahedral Pt-TFN / SnO2 material is prepared by using fluorotin niobate (TFN) as a structure directing agent and by redox reaction between the reducing carrier TFN and chloroplatinic acid, wherein Pt nanoparticles are embedded in the octahedral structure of TFN / SnO2, and the preparation comprises the following steps: 1) tin chloride and niobate aqueous solution are prepared respectively, the two liquids are mixed, hydrofluoric acid is added, the precursor is uniformly mixed, and then TFN solid is obtained by hydrothermal method; 2) the hydrothermally treated TFN is washed, centrifuged, dispersed with pure water, and then H2PtCl6 solution is added and stirred for a period of time; 3) the liquid is poured into a centrifuge tube for centrifugation, the waste liquid is discarded, and then the product is washed and centrifuged with pure water for multiple times, and then dried in a vacuum drying oven to obtain Pt-TFN / SnO2 material; In step 1), the amount of niobate is 0.2-0.3 g; the amount of tin chloride is 0.06-0.09 g; the concentration of hydrofluoric acid is 47 wt%, and the amount is 1-2 mL; the stirring time is 1-2 h, the hydrothermal temperature is 180℃, and the hydrothermal time is 24 h; In step 2), the amount of TFN is 0.2-0.3 g; the concentration of H2PtCl6 solution is 0.01 mol / L, and the amount is 430-500 μL; In step 2), the stirring time is 10-15 h.

2. The production method according to claim 1, characterized by, In step 3), the drying temperature is 50-70℃, and the drying time is 10-12 h.

3. The preparation method according to claim 1, characterized in that, In step 3), the washing treatment is to wash the separated precipitate 4-5 times with pure water, and the separation of the precipitate is centrifugation.

4. The Pt-TFN / Sn02 pudding structure prepared according to the preparation method of claim 1, characterized in that, Pt nanoparticles are embedded in TFN / SnO2 to form a pudding structure.

5. Application of the Pt-TFN / SnO2 material of claim 4 in the reaction of catalyzing the reduction of p-nitrophenol to p-aminophenol under alkaline conditions.

Images