A copper-doped Pd7Te3 nanowire, its preparation method and application

Abstract

The application discloses a preparation method of copper-doped Pd7Te3 nanowires, which comprises the following steps: adding tellurium nanowires into a palladium salt solution, adding copper salt, stirring and reacting, adding acetone to extract solid products, centrifuging, dispersing the obtained solid into a sodium hydroxide solution, stirring and reacting, and washing with a hydrochloric acid solution and water, so as to obtain the copper-doped Pd7Te3 nanowires. The preparation method of the copper-doped Pd7Te3 nanowires is simple, and the copper-doped Pd7Te3 nanowires have more excellent performance of electrocatalytic methanol oxidation compared with the undoped Pd7Te3 nanowires. The performance of the prepared copper-doped Pd7Te3 nanowires in electrocatalytic methanol oxidation at normal temperature and pressure can reach 1678 mAmg ‑1 , which is 2.82 times of that of commercial Pd / C.

Description

Technical Field

[0001] This invention relates to a copper-doped Pd7Te3 nanowire, its preparation method, and its application, belonging to the fields of material preparation and electrocatalysis. Background Technology

[0002] With the escalating global energy crisis, alkaline direct methanol fuel cells (ADMFCs) have attracted widespread attention as a promising alternative energy source. Methanol, known as liquid sunlight, boasts high energy density and is easily stored and transported. Furthermore, the alkaline electrolyte system implies faster anode methanol and cathode oxygen oxidation kinetics while effectively suppressing methanol permeation. Unfortunately, its large-scale commercial application remains hindered by low electrocatalyst activity, severe poisoning, and the currently high cost of platinum-based materials. Therefore, developing efficient and durable platinum-free / low-platinum electrocatalysts is crucial for the application of ADMFCs.

[0003] In recent years, palladium-containing nanomaterials have become important candidate materials for methanol oxidation anolyte electrocatalysts due to their excellent electrocatalytic performance and abundance three times higher than platinum. However, how to further improve their activity and overcome the strong adsorption of CO intermediates by palladium-based electrocatalysts remains a very challenging problem. Doping atoms not only provide more active sites but also modulate the intrinsic electronic structure of Pd through easier electron transfer. More importantly, the introduction of non-noble transition metals can guide the formation of OH*, which can further oxidize CO adsorbed on adjacent Pd sites. For example, compared with Pd nanowires, Fe-doped Pd nanowires exhibit a MOR activity of 1075.5 mA mg. -1 The activity of Ni-doped Pd nanoparticles in ethanol oxidation is higher than that of single Pd nanowires, which is attributed to the downward shift of the d-band center of Pd caused by the addition of Fe. In alkaline electrolyte, the activity of Ni-doped Pd nanoparticles in ethanol oxidation is 2368.22 mA mg. -1 This is higher than other reported Pd-based electrocatalysts. This is because the Ni(OH)₂ formed during the reaction absorbs OH⁻. - This leads to the local enrichment of OH*, which further renews the active sites of Pd.

[0004] Commercially available Pd-based catalysts almost all face difficulties such as complex preparation steps, dangerous operations, and harsh experimental conditions. For example, the synthesis of PdCu nanosheets requires two steps. First, ultrathin Pd nanosheets need to be synthesized as sacrificial templates. Then, Cu(acac)2 is added as a copper source and Ar gas is introduced. When Cu(acac)2 is reduced, Cu atoms are deposited on the surface of Pd nanosheets, and PdCu nanosheets are formed through the interdiffusion of Cu and Pd atoms.

[0005] In conclusion, developing a palladium-based catalyst with a simple preparation method that can efficiently catalyze the oxidation of methanol is of significant research importance. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a simple new method for preparing copper-doped Pd7Te3 nanowires; based on this method, the prepared material is used to achieve efficient methanol oxidation under normal temperature and pressure.

[0007] To achieve the above objectives, the present invention first provides a method for preparing copper-doped Pd7Te3 nanowires, comprising the following steps:

[0008] (1) Preparation of tellurium nanowires: Polyvinylpyrrolidone was dissolved in double-distilled water, stirred evenly, and sodium tellurite and ammonia were added in sequence, followed by hydrazine hydrate. After mixing evenly, the reaction solution was placed in a sealed container for reaction. After the reaction was completed, it was cooled to room temperature, mixed evenly with acetone, centrifuged, and then washed with water to obtain tellurium nanowires.

[0009] (2) Preparation of copper-doped Pd7Te3 nanowires: The tellurium nanowires prepared in step (1) were dispersed in water, the resulting dispersion was added to a palladium salt solution, and copper salt was added. After stirring evenly, the mixture was transferred to a high-pressure reactor for reaction. After cooling to room temperature, acetone was added to extract the solid product. After centrifugation, the obtained solid was dispersed in a sodium hydroxide solution. After stirring and reacting, it was washed with hydrochloric acid solution and water to obtain copper-doped Pd7Te3 nanowires.

[0010] In one embodiment of the present invention, in step (1), the mass-to-volume ratio of polyvinylpyrrolidone to double-distilled water is 0.02 to 0.04 g / mL.

[0011] In one embodiment of the present invention, in step (1), the mass ratio of sodium tellurite to polyvinylpyrrolidone added is 0.067 to 0.15.

[0012] In one embodiment of the present invention, in step (1), the mass-to-volume ratio of sodium tellurite to ammonia is 0.02 to 0.04 g / mL, and the mass-to-volume ratio of sodium tellurite to hydrazine hydrate is 0.04 to 0.1 g / mL.

[0013] In one embodiment of the present invention, in step (1), the reaction temperature is 170-180°C and the reaction time is 3-3.5 h.

[0014] In one embodiment of the present invention, in step (2), the mass-to-volume ratio of tellurium nanowire dispersion to palladium salt solution is 1 to 1.6, wherein the palladium salt includes at least one of H2PdCl4, sodium hypochlorite, and palladium chloride.

[0015] In one embodiment of the present invention, in step (2), the palladium salt is H2PdCl4, and the concentration of the palladium salt is 20-40 mM.

[0016] In one embodiment of the present invention, in step (2), the mass ratio of the copper salt to the tellurium nanowire is 8-10%, and the copper salt includes at least one of copper nitrate, copper chloride, and copper sulfate.

[0017] In one embodiment of the present invention, in step (2), the concentration of the copper salt is 60-100 mM.

[0018] In one embodiment of the present invention, in step (2), the reaction temperature in the high-pressure reactor is 80-120°C and the reaction time is 12-14h.

[0019] In one embodiment of the present invention, in step (2), the concentration of the sodium hydroxide solution used is 0.005-0.02M, the stirring reaction time is 12h, and the concentration of the hydrochloric acid solution is 0.005-0.02M.

[0020] The present invention also provides a copper-doped Pd7Te3 nanowire prepared according to the above preparation method.

[0021] The present invention also provides an application of the above-mentioned copper-doped Pd7Te3 nanowires in the field of electrocatalysis.

[0022] In one embodiment of the invention, the application includes electrocatalytic methanol oxidation.

[0023] The beneficial effects of this invention are:

[0024] (1) The preparation method is simple to operate. By using the synthesized tellurium nanowires, reacting them with palladium salts and copper salts, separating the reaction products and reacting them with sodium hydroxide, and then washing them with hydrochloric acid and water, copper-doped Pd7Te3 nanowires can be prepared.

[0025] (2) The Cu-doped Pd7Te3 nanowires prepared by the method of the present invention simultaneously promote the desorption of CO* and the adsorption of OH-, thereby rapidly renewing the active sites and improving the electroactivity and stability of MOR.

[0026] (3) The Cu-doped Pd7Te3 nanowires prepared by the method of the present invention can be used for electrocatalytic methanol oxidation. The mass activity of the catalytic methanol oxidation reaction can reach 1678 mA / mg, which is 1.82 times that of the undoped Pd7Te3 nanowires catalyzing methanol oxidation. Attached Figure Description

[0027] Figure 1The XRD diffraction patterns of Cu-doped Pd7Te3 nanowires and undoped Pd7Te3 nanowires prepared in Example 1 and Comparative Example 1 are shown. Line a is the XRD diffraction pattern of the undoped Pd7Te3 nanowires, and line b is the XRD diffraction pattern of the Cu-doped Pd7Te3 nanowires.

[0028] Figure 2 The images shown are transmission electron microscope (TEM) images and high-resolution transmission electron microscope (HRTEM) images of Cu-doped Pd7Te3 nanowires and undoped Pd7Te3 nanowires prepared in Example 1 and Comparative Example 1, respectively. In the images, a and b are the TEM and HRTEM images of the undoped Pd7Te3 nanowires, respectively, and c and d are the TEM and HRTEM images of the copper-doped Pd7Te3 nanowires, respectively.

[0029] Figure 3 The X-ray photoelectron spectroscopy (XPS) Cu 2p orbital spectra of Cu-doped Pd7Te3 nanowires and undoped Pd7Te3 nanowires prepared in Example 1 and Comparative Example 1 are shown. Line a is the X-ray photoelectron spectroscopy (XPS) Cu 2p orbital spectrum of the undoped Pd7Te3 nanowires, and line b is the X-ray photoelectron spectroscopy (XPS) Cu 2p orbital spectrum of the Cu-doped Pd7Te3 nanowires.

[0030] Figure 4 This is a comparison chart of the mass activity of electrocatalytic methanol oxidation in Example 2 and Comparative Example 5.

[0031] Figure 5 The X-ray photoelectron spectroscopy (XPS) Cu 2p orbital spectra of the Pd7Te3 nanowires prepared in Example 1 and Comparative Example 2 are shown.

[0032] Figure 6 The X-ray photoelectron spectroscopy (XPS) Cu 2p orbital spectra of the Pd7Te3 nanowires prepared in Example 1 and Comparative Example 3 are shown.

[0033] Figure 7 The X-ray photoelectron spectroscopy (XPS) Cu 2p orbital spectra of the Pd7Te3 nanowires prepared in Example 1 and Comparative Example 4 are shown. Detailed Implementation

[0034] Example 1

[0035] 1 g of PVP was placed in a 50 mL Teflon-lined container and dissolved in 33 mL of double-distilled water under strong magnetic stirring to form a homogeneous solution at room temperature. 0.0922 g of sodium tellurite (Na₂TeO₃, 0.5 mmol) was added to this solution and dissolved. Then, 3.33 mL of ammonia water and 1.67 mL of hydrazine hydrate were added to the mixed solution (total reaction volume 40 mL). The container was sealed and the reaction was carried out at 180 °C for 3 hours, after which the solution was rapidly cooled to room temperature with cold tap water.

[0036] Solid Te nanowires were extracted from a 50 mL Te nanowire dispersion using acetone and added to 40 mL of a 25 mM H₂PdCl₄ solution. Subsequently, 20 mL of 80 mM Cu(NO₃)₂·3H₂O was added to the above solution, and the mixture was stirred for 30 min. The mixture was then transferred to a 100 mL autoclave and stored at 80 °C for 12 h. After the product was allowed to cool naturally to room temperature, 150 mL of acetone was slowly added while continuously shaking to extract the solid product. The solid was then obtained by centrifugation and dispersed in a 0.01 M NaOH solution, followed by magnetic stirring for 12 h. Finally, the product was washed three times with 0.01 M HCl solution and water, respectively.

[0037] The structure of the compound prepared in Example 1 was identified, and the results are shown in the figure. Figures 1-3 , Figure 1 The middle b line is the XRD diffraction pattern of the Cu-doped Pd7Te3 nanowires prepared in Example 1; Figure 2 c and d are transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of Cu-doped Pd7Te3 nanowires prepared in Example 1, respectively. Figure 3 The middle b-line is the X-ray photoelectron spectroscopy (XPS) spectrum of the Cu-doped Pd7Te3 nanowires prepared in the example. From... Figure 1 It can be seen that the diffraction peaks at 40.3° and 40.1° belong to the (152) and (004) planes of cubic Pd7Te3 (JCPDS card number 43-1294), respectively, which proves that the product is Pd7Te3 nanowires. Figure 3 The middle b-line shows a peak with Cu 2P orbitals and no obvious Cu and CuO peaks, which proves that Cu doping has entered the Pd7Te3 nanowire.

[0038] Comparative Example 1

[0039] 1 g of PVP was placed in a 50 mL Teflon-lined container and dissolved in 33 mL of double-distilled water under strong magnetic stirring to form a homogeneous solution at room temperature. 0.0922 g of sodium tellurite (Na₂TeO₃, 0.5 mmol) was added to this solution and dissolved. Then, 3.33 mL of ammonia water and 1.67 mL of hydrazine hydrate were added to the mixed solution (total reaction volume 40 mL). The container was sealed and the reaction was carried out at 180 °C for 3 hours, after which the solution was rapidly cooled to room temperature with cold tap water.

[0040] Solid Te nanowires were extracted from a 50 mL Te nanowire dispersion using acetone. The extracted nanowires were then added to 40 mL of a 25 mM H₂PdCl₄ solution and stirred for 30 min. The mixture was then transferred to a 100 mL autoclave and stored at 80 °C for 12 h. After the product was allowed to cool naturally to room temperature, 150 mL of acetone was slowly added while continuously shaking to extract the solid product. The solid was then centrifuged and dispersed in a 0.01 M NaOH solution, followed by magnetic stirring for 12 h. Finally, the product was washed three times with 0.01 M HCl solution and water, respectively.

[0041] The morphology and structure of the compound prepared in Comparative Example 1 were identified, and the results are shown in the figure. Figures 1-3 , Figure 1 Line a in the middle is the XRD diffraction pattern of the Pd7Te3 nanowires prepared in Comparative Example 1. Figure 2 a and b are transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of the Pd7Te3 nanowires prepared in Comparative Example 1. Figure 3 The middle a-line is the XPS Cu 2p orbital spectrum of undoped Pd7Te3 nanowires. From... Figure 1 It can be seen that the diffraction peaks at 40.3 and 40.1 belong to the (152) and (004) planes of cubic Pd7Te3 (JCPDS card number 43-1294), respectively, which proves that the product is Pd7Te3 nanowires. Figure 3 As can be seen from line a, there is no Cu 2P orbital peak in the XPS curve. Therefore, the nanowires prepared in Comparative Example 1 are undoped Pd7Te3 nanowires.

[0042] Comparative Example 2

[0043] 1 g of PVP was placed in a 50 mL Teflon-lined container and dissolved in 33 mL of double-distilled water under strong magnetic stirring to form a homogeneous solution at room temperature. 0.0922 g of sodium tellurite (Na₂TeO₃, 0.5 mmol) was added to this solution and dissolved. Then, 3.33 mL of ammonia water and 1.67 mL of hydrazine hydrate were added to the mixed solution (total reaction volume 40 mL). The container was sealed and the reaction was carried out at 180 °C for 3 hours, after which the solution was rapidly cooled to room temperature with cold tap water.

[0044] Solid Te nanowires were extracted from a 50 mL Te nanowire dispersion using acetone and added to 40 mL of a 25 mM H₂PdCl₄ solution. Subsequently, 20 mL of a 20 mM Cu(NO₃)₂·3H₂O solution was added to the above solution, and the mixture was stirred vigorously for 30 min. The mixture was then transferred to a 100 mL autoclave and stored at 80 °C for 12 h. After the product was allowed to cool naturally to room temperature, 150 mL of acetone was slowly added while continuously shaking to extract the solid product. The solid was then obtained by centrifugation and dispersed in a 0.01 M NaOH solution, followed by magnetic stirring for 12 h. Finally, the product was washed three times with 0.01 M HCl solution and water, respectively. Figure 5 The XPS Cu 2p orbital spectrum of the Pd7Te3 nanowires prepared in Comparative Example 2 is shown below. Figure 5 The results show that there is no peak in the Cu 2P orbital, indicating that the product obtained is not Cu-doped Pd7Te3 nanowire.

[0045] Comparative Example 3

[0046] 1 g of PVP was placed in a 50 mL Teflon-lined container and dissolved in 33 mL of double-distilled water under strong magnetic stirring to form a homogeneous solution at room temperature. 0.0922 g of sodium tellurite (Na₂TeO₃, 0.5 mmol) was added to this solution and dissolved. Then, 3.33 mL of ammonia water and 1.67 mL of hydrazine hydrate were added to the mixed solution (total reaction volume 40 mL). The container was sealed and the reaction was carried out at 180 °C for 3 hours, after which the solution was rapidly cooled to room temperature with cold tap water.

[0047] Solid Te nanowires were extracted from a 50 mL Te nanowire dispersion using acetone and added to 40 mL of a 25 mM H₂PdCl₄ solution. Subsequently, 20 mL of a 40 mM Cu(NO₃)₂·3H₂O solution was added to the above solution, and the mixture was stirred vigorously for 30 min. The mixture was then transferred to a 100 mL autoclave and stored at 80 °C for 12 h. After the product was allowed to cool naturally to room temperature, 150 mL of acetone was slowly added while continuously shaking to extract the solid product. The solid was then obtained by centrifugation and dispersed in a 0.01 M NaOH solution, followed by magnetic stirring for 12 h. Finally, the product was washed three times with 0.01 M HCl solution and water, respectively. Figure 6 The XPS Cu 2p orbital spectrum of the Pd7Te3 nanowires prepared in Comparative Example 3 is shown below. Figure 6 The results show that there is no peak in the Cu 2P orbital, indicating that the product obtained is not Cu-doped Pd7Te3 nanowire.

[0048] Comparative Example 4

[0049] 1 g of PVP was placed in a 50 mL autoclave and dissolved in 33 mL of double-distilled water under strong magnetic stirring to form a homogeneous solution at room temperature. 0.0922 g of sodium tellurite (Na₂TeO₃, 0.5 mmol) was added to this solution and dissolved. Then, 3.33 mL of ammonia water and 1.67 mL of hydrazine hydrate were added to the mixed solution (total reaction volume 40 mL). The container was sealed and the reaction was carried out at 180 °C for 3 hours, after which the solution was rapidly cooled to room temperature with cold tap water.

[0050] Solid Te nanowires were extracted from a 50 mL Te nanowire dispersion using acetone and added to 40 mL of a 25 mM H₂PdCl₄ solution. Subsequently, 20 mL of a 20 mM Cu(NO₃)₂·3H₂O solution was added to the above solution, and the mixture was stirred vigorously for 30 min. The mixture was then transferred to a 100 mL autoclave and stored at 120 °C for 12 h. After the product was allowed to cool naturally to room temperature, 150 mL of acetone was slowly added while continuously shaking to extract the solid product. The solid was then obtained by centrifugation, dispersed in a 0.01 M NaOH solution, and magnetically stirred for 12 h. Finally, the product was washed three times with 0.01 M HCl solution and water, respectively. Figure 7 The XPS Cu 2p orbital spectrum of the Pd7Te3 nanowires prepared in Comparative Example 4 is shown below. Figure 7 The results show that there is no peak in the Cu 2P orbital, indicating that the product obtained is not Cu-doped Pd7Te3 nanowire.

[0051] Example 2: Electrocatalytic Methanol Oxidation Using Cu-Doped Pd7Te3 Nanowires

[0052] 5.645 μg of Cu-doped Pd7Te3 nanowires were uniformly dropped onto an electrode placed in a rotating disk electrode. 150 mL of water and 8.4 g of potassium hydroxide were added to the container, and the electrode was activated for 200 cycles at a current of 0.25 A. The electrode was then placed in a 150 mL solution of 1 M methanol and 1 M KOH, and methanol oxidation was performed at a current of 0.05 A. All solutions were pre-saturated with nitrogen gas. After 10 cycles, a stable methanol oxidation curve was obtained. The preparation method of the Cu-doped Pd7Te3 nanowires was the same as in Example 1.

[0053] Comparative Example 5

[0054] The difference between Comparative Example 5 and Example 2 is that the catalyst used is undoped Pd7Te3 nanowires, and the preparation method of the undoped Pd7Te3 nanowires is the same as that of Comparative Example 1.

[0055] Figure 4The figure shows the mass activity of the catalytic methanol oxidation in Example 2 and Comparative Example 5. As can be seen from the figure, the copper-doped Pd7Te3 nanowires have higher mass activity in the catalytic methanol oxidation. The mass activity of the copper-doped Pd7Te3 nanowires in the catalytic methanol oxidation can reach 1678 mA / mg, while the mass activity of the undoped Pd7Te3 nanowires in the catalytic methanol oxidation is only 920 mA / mg.

[0056] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing copper-doped Pd7Te3 nanowires, characterized in that, Includes the following steps: (1) Preparation of tellurium nanowires: Polyvinylpyrrolidone was dissolved in double-distilled water, stirred evenly, and sodium tellurite and ammonia were added in sequence, followed by hydrazine hydrate. After mixing evenly, the reaction solution was placed in a sealed container for reaction. After the reaction was completed, it was cooled to room temperature, mixed evenly with acetone, centrifuged, and then washed with water to obtain tellurium nanowires. (2) Preparation of copper-doped Pd7Te3 nanowires: The tellurium nanowires prepared in step (1) were dispersed in water, the resulting dispersion was added to a palladium salt solution, and copper salt was added. After stirring evenly, the mixture was transferred to a high-pressure reactor for reaction. After cooling to room temperature, acetone was added to extract the solid product. After centrifugation, the obtained solid was dispersed in a sodium hydroxide solution. After stirring and reacting, it was washed with hydrochloric acid solution and water to obtain copper-doped Pd7Te3 nanowires.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass-to-volume ratio of polyvinylpyrrolidone to double-distilled water is 0.02 to 0.04 g / mL, and the mass ratio of sodium tellurite to polyvinylpyrrolidone is 0.067 to 0.

15.

3. The preparation method according to claim 1, characterized in that, In step (1), the mass-to-volume ratio of sodium tellurite to ammonia is 0.02–0.04 g / mL, the mass-to-volume ratio of sodium tellurite to hydrazine hydrate is 0.04–0.1 g / mL, the reaction temperature is 170–180 °C, and the reaction time is 3–3.5 h.

4. The preparation method according to claim 1, characterized in that, In step (2), the volume ratio of tellurium nanowire dispersion to palladium salt solution is 1 to 1.6, and the palladium salt includes at least one of H2PdCl4, sodium hypochlorite, and palladium chloride.

5. The preparation method according to claim 1, characterized in that, In step (2), the palladium salt is H2PdCl4, and the concentration of the palladium salt is 20-40 mM.

6. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the copper salt to the tellurium nanowire is 8-10%, the copper salt includes at least one of copper nitrate, copper chloride, and copper sulfate, and the concentration of the copper salt is 60-100 mM.

7. The preparation method according to claim 1, characterized in that, In step (2), the reaction temperature in the high-pressure reactor is 80-120°C and the reaction time is 12-14h.

8. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the sodium hydroxide solution used is 0.005-0.02M, the stirring reaction time is 12h, and the concentration of the hydrochloric acid solution is 0.005-0.02M.

9. Copper-doped Pd7Te3 nanowires prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the copper-doped Pd7Te3 nanowires of claim 9 in the field of electrocatalysis, wherein the application includes electrocatalytic methanol oxidation.

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