Method for preparing tungsten trioxide supported platinum catalyst under assistance of solid-phase microwave technology and application of tungsten trioxide supported platinum catalyst

Abstract

The invention relates to a preparation method and application of an electrocatalyst for a seawater-based battery, and belongs to the technical field of new energy materials. The tungsten trioxide supported platinum catalyst (Pt / / WO3-V) is prepared with the assistance of a solid-phase microwave technology, and the material has rich oxygen vacancies and active centers. The oxygen vacancy not only can regulate and control the electronic structure of Pt, but also can enhance the corrosion resistance to Cl <-> in seawater, so that the catalytic activity and chlorine resistance of oxygen reduction reaction (ORR) are remarkably improved. A seawater electrolyte zinc-air battery assembled by using the catalyst as a cathode shows relatively high power density and good cycling stability, and shows relatively good application prospects in seawater batteries.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new energy materials, and particularly relates to a synthesis method of a platinum-loaded tungsten trioxide catalyst based on solid-phase microwave assistance and application of the platinum-loaded tungsten trioxide catalyst in a seawater zinc-air battery. BACKGROUND

[0002] With the continuous growth of global energy demand, the overconsumption of traditional energy has caused serious pressure on the environment. Seawater-based metal-air batteries have become an important development direction of the new generation of energy storage and supply technologies due to their high energy conversion efficiency, environmental friendliness, and abundant seawater resources. However, the positive electrode oxygen reduction reaction (ORR) kinetics of seawater-based metal-air batteries is slow, which limits the energy conversion efficiency. At the same time, seawater contains a large amount of Cl - , which is easy to poison the metal active sites and cause catalyst poisoning, reducing the catalytic efficiency and chlorine resistance. Although the commercial Pt / C catalyst has high activity, it is difficult to meet the actual application requirements due to high cost, resource shortage, and insufficient chlorine resistance. Therefore, the development of an oxygen reduction electrocatalyst with high activity and chlorine resistance is of great significance to improve the performance of seawater batteries and expand their application in the field of marine equipment and energy storage. SUMMARY

[0003] The purpose of the present application is to provide a synthesis method and application of a tungsten trioxide-supported platinum oxygen reduction electrocatalyst (Pt / / WO 3-V ) prepared by solid-phase microwave technology. The electrocatalyst with oxygen vacancies can significantly improve the ORR electrocatalytic performance, and the Pt / / WO 3-V applied as an air positive electrode in seawater-based zinc-air batteries exhibits excellent performance.

[0004] To achieve the above-mentioned purposes, the present application provides the following technical solutions:

[0005] The preparation method of the tungsten trioxide-supported platinum oxygen reduction electrocatalyst prepared by solid-phase microwave technology provided by the present application can be realized by the following preparation route:

[0006] (1) Preparation of WO 3-V : 0.1-0.3 g of W(CO)6 and 0.3-1.0 g of Ketjenblack (KB) are ground in a mortar for 10-30 min, and are fully mixed and uniform. It is placed in a microwave oven (700 W) for microwave reaction for 30-90 s to obtain WO 3-V .

[0007] (2) Synthesis of Pt / / WO 3-V : The prepared WO 3-V is placed in 10 mg mL -1The solution was sonicated in H₂PtCl₄ solution for 0.5–1 h to mix thoroughly. The sonicated solution was washed twice with deionized water and twice with ethanol, centrifuged, and dried overnight in a 60°C oven to obtain Pt / / WO₄. 3-V .

[0008] According to the preparation method of the technical route, the characteristic is that: in step (1), the mass ratio of W(CO)6 and KB is 1:3, and the microwave time is 30-90s, so as to synthesize an electrocatalyst with abundant oxygen vacancies in a short time.

[0009] According to the preparation method of the technical route, the characteristic is that the concentration of H2PtCl4 in step (2) is 10-50 mg / mL. -1 Pt is introduced through solution to control the doping content of Pt to a low level, thereby controlling costs.

[0010] Compared with existing technologies, this invention is the first to propose the use of solid-phase microwave technology to assist in the preparation of tungsten trioxide-supported platinum-oxygen reduction electrocatalysts, and has the following advantages:

[0011] (1) A platinum catalyst supported on tungsten trioxide with oxygen vacancies was obtained by solid-phase microwave treatment. The method is simple, green and environmentally friendly, which can effectively reduce the amount of precious metals used, significantly reduce production costs, and is suitable for large-scale preparation.

[0012] (2) When the catalyst prepared by the method of the present invention is applied to a seawater-based zinc-air battery, the catalyst exhibits a half-wave potential higher than 0.84V and a limiting current density close to 6mA / cm² in the half-cell. -2 Its performance is similar to that of commercial Pt / C catalysts;

[0013] (3) This invention provides an efficient and economical synthetic route, and the resulting catalyst has abundant and uniformly distributed active sites, which is beneficial for electron transport and improved reaction kinetics. Simultaneously, this material can effectively resist Cl in seawater. - Plasma adsorption and corrosion overcome the problems of insufficient activity, low electron transfer efficiency and uneven site distribution of traditional catalysts, and have important application prospects for clean energy technologies such as seawater metal-air batteries. Attached Figure Description

[0014] Figure 1 The Pt / / WO prepared in Example 1 3-V X-ray diffraction (XRD) pattern of the material;

[0015] Figure 2 The Pt / / WO prepared in Example 1 3-V High-resolution transmission electron microscopy (HRTEM) image of the material;

[0016] Figure 3The Pt / / WO prepared in Example 1 3-V Test diagrams of specific surface area (BET) and pore size distribution of the material;

[0017] Figure 4 The Pt / / WO prepared in Example 1 3-V Electron paramagnetic resonance (EPR) spectra of the material;

[0018] Figure 5 The Pt / / WO prepared in Example 1 3-V Cyclic voltammetry (a) and Pt / / WO prepared in Example 1 3-V ORR performance test graph (b) of Pt / / WO3-30 prepared in Example 2 and Pt / / WO3-60 prepared in Example 3;

[0019] Figure 6 The stability test curve and accelerated durability test curve (3000 cycles) of Example 1 of the present invention in 0.1M KOH seawater solution are shown.

[0020] Figure 7 For example, Pt / / WO in Example 1 3-V The discharge curves and power density diagrams (a) of the seawater electrolyte zinc-air battery assembled from the materials, and the power density diagrams at different current densities (1, 2, 5, 10, 20, 30, 50 mA cm⁻¹). -2 (b) Proportion chart;

[0021] Figure 8 For example, Pt / / WO in Example 1 3-V A constant current charge-discharge cycle test diagram of a seawater electrolyte zinc-air battery assembled from the materials. Detailed Implementation

[0022] Example 1

[0023] This invention relates to a method for synthesizing a tungsten trioxide-supported platinum oxygen reduction electrocatalyst using solid-phase microwave technology, comprising the following steps:

[0024] (1) Grind 0.12g of W(CO)6 and 0.36g of KB in a mortar for 30 minutes until well mixed. Place the mixture in a microwave oven (700W) and microwave for 90 seconds to obtain WO3. 3-V .

[0025] (2) The WO 3-V Add 10mg mL -1 The solution was sonicated in H₂PtCl₄ solution for 1 hour to mix thoroughly. The sonicated solution was washed twice with deionized water and twice with ethanol, centrifuged, and dried overnight in a 60°C oven to obtain Pt / / WO₄.3-V (Pt≈3.3wt%).

[0026] X-ray diffraction (XRD) was used to analyze the Pt-doped oxygen-vacancy-rich WO3 prepared by the above method. 3-V Phase analysis of the material yielded the following results: Figure 1 As shown, this proves that the material formed the WO3 phase, and no Pt phase was found. Combined with XPS and mapping, it is proved that Pt exists in a doping manner.

[0027] High-resolution transmission electron microscopy (TEM) was used to study Pt-doped oxygen-rich vacancy WO3 sites. 3-V The microstructure of the material, such as Figure 2 As shown in (a) and (b), it can be clearly seen that the lattice fringes of the sample correspond to the (001) and (220) crystal planes of WO3, proving the existence of WO3.

[0028] Nitrogen adsorption-desorption method for Pt-doped oxygen-rich WO3 3-V The material was tested. The results showed that the specific surface area was 858.9 m². 2 ·g -1 The pore size distribution in the illustration is predominantly mesoporous, which is beneficial for mass transport and exposure of active sites, thereby improving oxygen reduction reaction performance.

[0029] Electron paramagnetic resonance (EPR) spectroscopy was used to analyze Pt / / WO3. 3-V Oxygen vacancy research was conducted on oxygen vacancy materials. Figure 4 The signal intensity was significantly stronger at a g value of 2.003, which is a signal peak associated with oxygen vacancies, indicating that microwave duration promotes the generation of oxygen vacancies.

[0030] 5 mg of catalyst was dispersed in a mixture of 1 mL ethanol and 40 μL 5 wt% Nafion solution, and sonicated for 1 h to obtain a homogeneous slurry. 10 μL of this slurry was drop-coated onto the surface of a glassy carbon electrode and allowed to dry naturally before electrochemical testing. A three-electrode system was used: a glassy carbon electrode as the working electrode, a graphite electrode as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was a mixture of 0.1 M KOH and seawater. Cyclic voltammetry results ( Figure 5 a) indicates that the material exhibits a significant oxygen reduction peak under oxygen saturation conditions, while showing no peak under a nitrogen atmosphere, demonstrating significant ORR activity. Linear scan results ( Figure 5 b) Further evidence shows that its half-wave potential and limiting current are both close to 20% Pt / C, indicating that the catalyst has excellent oxygen reduction performance.

[0031] X-ray diffraction (XRD) was used to analyze the Pt-doped oxygen-vacancy-rich WO3 prepared by the above method. 3-VThe material underwent stability testing and retained approximately 92% of its initial current after a 12-hour IT test. Figure 6 This proves that Pt / / WO 3-V It exhibits excellent stability.

[0032] Example 2

[0033] This invention relates to a method for synthesizing a platinum-supported oxygen reduction electrocatalyst using solid-phase microwave technology, comprising the following steps:

[0034] (1) Take 0.12g of W(CO)6 and 0.36g of KB and grind them in a mortar for 30min to mix them evenly. Place them in a microwave oven (700W) and microwave for 30s to obtain WO3-30.

[0035] (2) The WO 3-V Add 10mg mL -1 The solution was sonicated in H2PtCl4 solution for 1 h to mix thoroughly. The sonicated solution was washed twice with deionized water and twice with ethanol, centrifuged, and dried overnight in a 60℃ oven to obtain Pt / / WO3-30 (Pt≈2.3wt%). Electrochemical tests were then performed in a three-electrode system using 0.1M KOH + seawater as the electrolyte. The electrocatalyst prepared by the above method exhibited excellent ORR activity. Figure 5 b).

[0036] Example 3

[0037] This invention relates to a method for synthesizing a platinum-supported oxygen reduction electrocatalyst using solid-phase microwave technology, comprising the following steps:

[0038] (1) Take 0.12g of W(CO)6 and 0.36g of KB and grind them in a mortar for 30min to mix them evenly. Place them in a microwave oven (700W) and microwave for 60s to obtain WO3-60.

[0039] (2) The WO 3-V Add 10mg mL -1 The solution was sonicated in H2PtCl4 solution for 1 h to mix thoroughly. The sonicated solution was washed twice with deionized water and twice with ethanol, centrifuged, and dried overnight in a 60℃ oven to obtain Pt / / WO3-60 (Pt≈2.8wt%). Electrochemical tests were then performed in a three-electrode system using 0.1M KOH + seawater as the electrolyte. The electrocatalyst prepared by the above method exhibited excellent ORR activity. Figure 5 b).

[0040] To verify the feasibility of a practical seawater zinc-air battery, the catalyst was placed in a mold for testing. The results are as follows:Figure 7 As shown in (a), its power density was found to be 192 mW cm⁻¹. -2 It exhibited superior performance compared to commercially available 20% Pt / C. Figure 7 As shown in (b), its rate capability was found to be significantly superior to that of commercial 20% Pt / C. Simultaneously, it exhibited better long-term cycling stability. Figure 8 This study provides a promising prospect for the application of tungsten trioxide-supported platinum oxygen reduction electrocatalysts prepared by solid-phase microwave technology in seawater zinc-air batteries.

[0041] This invention constructs a WO3 support rich in oxygen vacancies and with a large specific surface area by Pt doping, exposing more active sites and significantly improving electron conduction and mass transport efficiency. The strong metal-support interaction between the metal particles and WO3 allows electrons to migrate to Pt via oxygen bridges, forming an electron-rich layer that effectively repels Cl from seawater. - This reduces the erosion of ORR sites, thereby significantly enhancing catalytic activity and stability. This study provides a new approach and a simple synthetic route for designing highly efficient and corrosion-resistant seawater electrolyte cathode catalysts.

[0042] The above description is not intended to limit the present invention. It should be noted that for those skilled in the art, various changes, modifications, additions or substitutions can be made without departing from the essential scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a Pt-doped electrocatalyst with oxygen vacancies for use in seawater zinc-air batteries, characterized in that, Includes the following steps: (1) Rich in oxygen vacancies (WO) 3-V Solid-phase microwave rapid preparation of the support: Tungsten hexacarbonyl (W(CO)6) and Ketjen black (KB) were ground in a mortar and thoroughly mixed. The mixture was then placed in a microwave oven (700W) for microwave reaction to obtain a solid. (2) Soaking treatment: The prepared WO 3-V The mixture was ultrasonicated in an H₂PtCl₄ solution until homogeneous. The ultrasonicated solution was washed twice with deionized water and twice with ethanol, centrifuged, and dried overnight in a 60°C oven. This yielded an electrocatalyst for the oxygen reduction reaction at the positive electrode in a seawater-based zinc-air battery.

2. The method for preparing a Pt-doped electrocatalyst with oxygen vacancies for use in seawater zinc-air batteries according to claim 1, characterized in that, In step (1), 0.12-0.6g of W(CO)6 and 0.36-1.8g of KB are added in a ratio of 1:

3.

3. The method for preparing a Pt-doped electrocatalyst with oxygen vacancies for use in seawater zinc-air batteries according to claim 1, characterized in that, The microwave duration in step (1) is 30s-90s.

4. The method for preparing a Pt-doped electrocatalyst with oxygen vacancies for use in seawater zinc-air batteries according to claim 1, characterized in that, The ultrasound time in step (2) is 10 min to 60 min.

5. The method for preparing a Pt-doped electrocatalyst with oxygen vacancies for use in seawater zinc-air batteries according to claim 1, characterized in that, The concentration of the H2PtCl4 solution in step (2) is 10 mg / mL. -1 -50mg mL -1 of.

6. The electrocatalyst with oxygen vacancies according to claim 1, characterized in that: It can exhibit excellent ORR activity, with a half-wave potential of over 0.84V. Furthermore, seawater-based zinc-air batteries constructed using it as the positive electrode for air can achieve stable charge-discharge operation over a long period of time.

7. The test conditions for the seawater-based zinc-air battery according to claims 1-3, characterized in that, An electrolyte solution of 6M KOH + 0.2M Zn(OAc)2 was prepared using natural seawater, and the electrolyte was tested at 10 mA cm⁻¹. -2 Charge and discharge tests were conducted at a current density of [value missing].

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