Catalytic material of tungsten oxide and carbon-loaded platinum as well as preparation and application of catalytic material

Abstract

The invention relates to a tungsten oxide and carbon-loaded platinum catalytic material which is characterized in that tungsten oxide and XC-72C are used as carriers to load platinum, the mass ratio of platinum to tungsten oxide to XC-72C is 1: (9-36): (14-120), and the mass fraction of platinum is 0.5%-4%. Meanwhile, the invention further discloses a preparation method and application of the catalytic material. The preparation method is convenient to prepare and simple to operate, and the obtained Pt-W18O49 / C catalytic material is low in platinum content, high in intrinsic activity and good in stability and can be widely applied as a PEM water electrolysis hydrogen production cathode catalyst.

Description

Technical Field

[0001] The invention relates to the field of proton exchange membrane water electrolyzer catalysts, and in particular to a tungsten suboxide and carbon-supported platinum catalytic material and a preparation method and application thereof. Background Art

[0002] Due to the scarcity of fossil fuels, the dominance of the global energy system needs to be gradually replaced by renewable energy. Renewable energy (such as wind power, solar energy, etc.) is characterized by volatility and intermittency. If it is connected to the grid on a large scale, it will affect the safe and stable operation of the power grid. As an important secondary energy source, hydrogen energy has the advantages of high energy density and green and pollution-free. If renewable energy is used to electrolyze water to produce hydrogen, it will not only provide a new way for renewable energy consumption, but also greatly reduce the cost of hydrogen production. Proton exchange membrane (PEM) water electrolysis to produce hydrogen is a technology that can adapt to the intermittent nature of renewable energy and has fast dynamic response, and has the prospect of large-scale application. However, the operating conditions of PEM electrolyzers are harsh, and currently they can only rely on Pt and Ir-based precious metal catalysts. The high prices of these precious metals hinder the deployment of terawatt-level PEM electrolysis technology in the future. This limitation has prompted the development of highly active, low-Pt hydrogen evolution (HER) catalysts.

[0003] The apparent activity of a catalyst depends on the number of active sites and the activity of a single active site. Therefore, current research on cathode catalysts for PEM water electrolysis is also mainly focused on increasing the number of active sites per unit area and increasing the intrinsic activity of Pt. On the one hand, in order to improve the atomic utilization of Pt, researchers reduce the size of the catalyst, such as shrinking Pt particles to sub-nanoclusters or even single atoms. On the other hand, the intrinsic activity of each active site is also a key factor that directly determines the performance of the electrocatalyst. For supported Pt nanoparticles, due to quantum size effects and surface geometry effects, the reduction of atomicity always greatly enhances the reactivity. In the case of atomically dispersed Pt, the coordinated unsaturated Pt sites can interact moderately with hydrogen reaction intermediates, thereby showing good hydrogen evolution reaction (HER) activity. In addition, the interaction between Pt and the carrier changes the electronic structure of Pt, thereby increasing the intrinsic activity of the Pt site; at the same time, the synergistic effect can reduce the adsorption / desorption barriers of hydrogen active substances around the Pt / carrier interface, thereby improving the HER performance. However, existing cathode catalysts for PEM water electrolyzers have defects such as high platinum content and poor intrinsic activity. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a catalytic material of tungsten suboxide and carbon-supported platinum with low platinum content, high activity and good stability.

[0005] Another technical problem to be solved by the present invention is to provide the preparation of the catalytic material of tungsten suboxide and carbon-supported platinum.

[0006] The third technical problem to be solved by the present invention is to provide application of the tungsten suboxide and carbon-supported platinum catalytic material.

[0007] In order to solve the above problems, the present invention discloses a catalytic material of tungsten suboxide and carbon-supported platinum, characterized in that: the catalytic material is composed of tungsten suboxide (W 18 O 49 ) and XC-72C as carriers to load platinum (Pt), among which platinum (Pt), tungsten suboxide (W 18 O 49 The mass ratio of ) and XC-72C is 1:9~36:14~120, and the mass fraction of platinum (Pt) is 0.5%~4%.

[0008] The tungsten suboxide (W 18 O 49 ) is prepared by the following method: tungsten salt and urea are dispersed in excess anhydrous ethanol, and a dark blue precursor is obtained after the anhydrous ethanol is completely evaporated; the dark blue precursor is obtained by high-temperature calcination; the mass ratio of the tungsten salt to the urea is 5:1~10:1.

[0009] The tungsten salt is WCl6.

[0010] The high temperature calcination condition is to increase the temperature to 700°C-800°C at a heating rate of 0.2°C / min-10°C / min under Ar atmosphere and keep the temperature for 3-4 hours.

[0011] The method for preparing a catalytic material of tungsten suboxide and carbon-supported platinum as described above is characterized in that: the method is to first weigh according to the ratio; then add tungsten suboxide (W 18 O 49 ), after ultrasonic stirring, platinum salt and XC-72C were added in sequence, and stirring was continued. The obtained dispersion was freeze-dried to obtain a black solid; the black solid was reduced at high temperature to obtain Pt-W 18 O 49 / C catalytic material; the mass ratio of the ultrapure water to the tungsten suboxide is 1:10~1:20; the mass ratio of the platinum salt, the tungsten suboxide, and the XC-72C is 1:3~36:5~120.

[0012] The platinum salt is present at a concentration of 10 mg mL -1 of chloroplatinic acid solution.

[0013] The high temperature reduction condition refers to keeping the temperature at 250°C to 350°C for 2 to 4 hours in a mixed atmosphere of H2 and Ar; the volume fraction of H2 in the mixed atmosphere of H2 and Ar is 5% to 10%.

[0014] The application of the tungsten suboxide and carbon-supported platinum catalytic material as described above is characterized in that the catalytic material is used as a cathode catalyst in a proton exchange membrane water electrolyzer in an acidic water electrolysis oxygen evolution reaction.

[0015] Compared with the prior art, the present invention has the following advantages: 1. Pt-W of the present invention 18 O 49 / C catalytic materials have low platinum content and high intrinsic activity, which greatly reduces the cost of using catalytic materials.

[0016] 2. Pt-W of the present invention 18 O 49 / C catalytic material has good stability and can exist stably in acidic media. It can be widely used as a cathode catalyst for PEM water electrolysis to produce hydrogen.

[0017] 3. The present invention is easy to prepare, simple to operate, and can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0019] Figure 1 W of the present invention 18 O 49 Scanning electron microscope image of .

[0020] Figure 2 The Pt-W prepared in Example 1 of the present invention 18 O 49 SEM image of the / C catalyst.

[0021] Figure 3 This is the test result of linear sweep voltammetry in 0.5 M H2SO4 in the present invention.

[0022] Figure 4 The polarization curve of the electrolytic cell in the present invention is shown in Figure 2. The effective area of ​​the electrode is 4 cm 2 , the test temperature is 80℃. DETAILED DESCRIPTION

[0023] A catalytic material of tungsten suboxide and carbon-supported platinum, the catalytic material comprising tungsten suboxide (W 18 O 49 ) and XC-72C as carriers to load platinum (Pt), among which platinum (Pt), tungsten suboxide (W 18 O 49 ) and XC-72C in a mass ratio (g / g) of 1:9~36:14~120, and the mass fraction of platinum (Pt) is 0.5%~4%.

[0024] Among them: tungsten suboxide (W 18 O 49 ) is prepared by the following method: tungsten salt and urea are dispersed in excess anhydrous ethanol to partially reduce the tungsten salt, and after the anhydrous ethanol is completely evaporated, a dark blue precursor is obtained; the dark blue precursor is heated to 700℃~800℃ at a heating rate of 0.2℃ / min~10℃ / min in Ar atmosphere for high-temperature calcination, and the temperature is kept for 3~4 hours to obtain the product.

[0025] The tungsten salt is WCl6. The mass ratio (g / g) of the tungsten salt to urea is 5:1~10:1.

[0026] The dispersant of tungsten salt is ethanol, because ethanol can reduce high-valent tungsten salt and is easy to volatilize to obtain a solid precursor.

[0027] A method for preparing a catalytic material of tungsten suboxide and carbon-supported platinum, the method comprising first weighing according to a proportion; then adding tungsten suboxide (W 18 O 49 ), the mass ratio (g / g) of ultrapure water to tungsten suboxide is 1:10~1:20. After ultrasonic stirring, platinum salt and XC-72C are added in sequence, and stirring is continued. The mass ratio (g / g) of platinum salt, tungsten suboxide and XC-72C is 1:3~36:5~120. The obtained dispersion is freeze-dried to obtain a black solid; the black solid is reduced at 250℃~350℃ in a mixed atmosphere of H2 and Ar, and kept warm for 2~4 h to obtain Pt-W with good catalytic performance and high stability. 18 O 49 / C catalytic material. The volume fraction of H2 in the mixed atmosphere of H2 and Ar (L / L) is 5%~10%.

[0028] Where: Platinum salt is at a concentration of 10 mg mL -1 of chloroplatinic acid solution.

[0029] The invention discloses an application of a catalytic material of tungsten suboxide and carbon-supported platinum. The catalytic material is used as a cathode catalyst in a proton exchange membrane water electrolyzer in an acidic water electrolysis oxygen evolution reaction.

[0030] The reagents used in the examples of the present invention are all commercially available.

[0031] Example 1 1. W 18 O 49 Preparation Add 500 mg WCl6 to 50 mL anhydrous ethanol solution, stir evenly with a magnetic stirrer, then add 75 mg urea, continue stirring until the ethanol is completely volatilized, scrape off the reaction precursor, grind it thoroughly with a mortar, move it to a tube furnace, and heat it to 700℃~800℃ at a heating rate of 0.2℃ / min~10℃ / min in an Ar atmosphere, and keep it warm for 3~4h. Finally, cool it naturally to obtain W 18 O 49 .

[0032] The prepared W 18 O 49 Scanning electron microscopy revealed Figure 1 As shown in the figure, the nanorod-shaped W 18 O 49 .

[0033] 2. Pt Load The mass fraction of Pt was 4%. 200 mg of W prepared in the above steps was taken. 18 O 49 20 mL ultrapure water, ultrasonically homogenized by ultrasonic cleaning machine. 10 mg mL -1 5.92 mL of chloroplatinic acid solution was added and stirred for 10 h with the help of a magnetic stirrer. 333 mg of XC-72C was added to the dispersion and continued to stir until uniform. The dispersion was then freeze-dried and the resulting powder was placed in a tube furnace and kept at 250°C~350°C for 2~4 h in a 10% H2 / Ar atmosphere. Finally, the temperature was naturally lowered to obtain Pt-W 18 O 49 / C catalytic material.

[0034] The prepared Pt-W 18 O 49 The / C catalytic material was scanned by electron microscope. The results are as follows Figure 2 As shown in the figure, the nanorod-shaped Pt-W 18 O 49 / C,W 18 O 49 There was no obvious change in the carrier morphology before and after.

[0035] 3. Electrochemical test Take 4 mg of the prepared Pt-W 18 O 49 / C, dispersed in 1 mL Nafion water and isopropanol mixed solution, after half an hour of ultrasonication, 15 μL of the dispersion was dropped on the glassy carbon electrode, and after natural drying, the linear sweep voltammetry of the electrochemical workstation was used to evaluate the Pt-W 18 O49 / C catalyst electrochemical performance, where saturated calomel electrode was used as reference electrode, carbon rod was used as counter electrode, 0.5 M H2SO4 was used as electrolyte, and the scan rate was 5 mV / s.

[0036] The test results are as follows Figure 3 As shown in the figure, the Pt-W prepared in Example 1 18 O 49 The test electrode made of / C catalyst was -2 The overpotential is 4 mV.

[0037] 4. PEM water electrolysis hydrogen production device test The prepared Pt-W 18 O 49 / C was sprayed on the diffusion layer carbon paper as the cathode catalyst of the PEM electrolyzer with a loading of 3.6 mg cm -2 The anode is IrO2 sprayed on titanium fiber felt with a loading of 2 mg cm -2 The proton exchange membrane Nafion 117 was sandwiched between the two electrodes mentioned above, hot pressed at 130°C and 2 MPa to form a membrane electrode, assembled into an electrolytic cell, and its electrochemical performance was tested.

[0038] The test results are as follows Figure 4 As shown in the figure, the Pt-W prepared in Example 1 18 O 49 / C catalyst prepared membrane electrode at 1 A cm -2 , the battery tank voltage at 80°C is only 1.742 V; it also shows that the Pt-W prepared in Example 1 18 O 49 The membrane electrode prepared with / C catalyst can effectively improve the utilization rate of water electrolysis catalyst and enhance the reaction performance.

[0039] Example 2 1. W 18 O 49 The preparation is the same as in Example 1.

[0040] 2. Pt Load The mass fraction of Pt was 0.5%. 200 mg of W prepared in the above steps was taken. 18 O 49 20 mL ultrapure water, ultrasonically homogenized by ultrasonic cleaning machine. 10 mg mL -10.67 mL of chloroplatinic acid solution was added and stirred for 10 h with the help of a magnetic stirrer. 304 mg of XC-72C was added to the dispersion and continued to stir until uniform. The dispersion was then freeze-dried and the resulting powder was placed in a tube furnace and kept at 250°C~350°C for 2~4 h in a 10% H2 / Ar atmosphere. Finally, the temperature was naturally lowered to obtain the sample.

[0041] 3. Electrochemical test is the same as in Example 1.

[0042] The test results are as follows Figure 3 As shown in the figure, the Pt-W prepared in Example 2 18 O 49 The test electrode made of / C catalyst was -2 The overpotential is 91 mV.

[0043] 4. The test of PEM water electrolysis hydrogen production device is the same as that of Example 1.

[0044] The test results are as follows Figure 4 As shown in the figure, the Pt-W prepared in Example 2 18 O 49 / C catalyst prepared membrane electrode at 1 A cm -2 , the battery tank voltage at 80°C is only 1.865 V; it also shows that the Pt-W prepared in Example 1 18 O 49 The membrane electrode prepared with / C catalyst can effectively improve the utilization rate of water electrolysis catalyst and enhance the reaction performance.

[0045] Example 3 1. W 18 O 49 The preparation is the same as in Example 1.

[0046] 2. Pt Load The mass fraction of Pt was 1%. 200 mg of W prepared in the above steps was taken. 18 O 49 20 mL ultrapure water, ultrasonically homogenized by ultrasonic cleaning machine. 10 mg mL -1 1.34 mL of chloroplatinic acid solution was added and stirred for 10 h with the help of a magnetic stirrer. 308 mg of XC-72C was added to the dispersion and continued to stir until uniform. The dispersion was then freeze-dried and the resulting powder was placed in a tube furnace and kept at 250°C~350°C for 2~4 h in a 10% H2 / Ar atmosphere. Finally, the temperature was naturally lowered to obtain the sample.

[0047] 3. Electrochemical test is the same as in Example 1.

[0048] The test results are as follows Figure 3 As shown in the figure, the Pt-W prepared in Example 3 18 O 49 The test electrode made of / C catalyst was -2 The overpotential is 35 mV.

[0049] 4. The test of PEM water electrolysis hydrogen production device is the same as that of Example 1.

[0050] The test results are as follows Figure 3 As shown in the figure, the Pt-W prepared in Example 3 18 O 49 / C catalyst prepared membrane electrode at 1 A cm -2 , the battery tank voltage at 80°C is only 1.847 V; it also shows that the Pt-W prepared in Example 1 18 O 49 The membrane electrode prepared with / C catalyst can effectively improve the utilization rate of water electrolysis catalyst and enhance the reaction performance.

[0051] Example 4 1. W 18 O 49 The preparation is the same as in Example 1.

[0052] 2. Pt Load The mass fraction of Pt was 2%. 200 mg of W prepared in the above steps was taken. 18 O 49 20 mL ultrapure water, ultrasonically homogenized by ultrasonic cleaning machine. 10 mg mL -1 2.79 mL of chloroplatinic acid solution was added and stirred for 10 h with the help of a magnetic stirrer. 318 mg of XC-72C was added to the dispersion and continued to stir until uniform. The dispersion was then freeze-dried and the resulting powder was placed in a tube furnace and kept at 250°C~350°C for 2~4 h in a 10% H2 / Ar atmosphere. Finally, the temperature was naturally lowered to obtain the sample.

[0053] 3. Electrochemical test is the same as in Example 1.

[0054] The test results are as follows Figure 3 As shown in the figure, the Pt-W prepared in Example 4 18 O 49 The test electrode made of / C catalyst was -2 The overpotential is 17 mV.

[0055] 4. The test of PEM water electrolysis hydrogen production device is the same as that of Example 1.

[0056] The test results are as follows Figure 3 As shown in the figure, the Pt-W prepared in Example 4 18 O 49 / C catalyst prepared membrane electrode at 1 A cm -2 , the battery tank voltage at 80°C is only 1.757 V; it also shows that the Pt-W prepared in Example 1 18 O 49 The membrane electrode prepared with / C catalyst can effectively improve the utilization rate of water electrolysis catalyst and enhance the reaction performance.

Claims

1. A catalytic material of tungsten suboxide and carbon-supported platinum, characterized in that: The catalytic material is composed of tungsten suboxide and XC-72C as carriers to load platinum, wherein the mass ratio of platinum, tungsten suboxide and XC-72C is 1:9~36:14~120, and the mass fraction of platinum is 0.5%~4%.

2. The catalytic material of tungsten suboxide and carbon-supported platinum according to claim 1, characterized in that: The tungsten suboxide is prepared by the following method: tungsten salt and urea are dispersed in excess anhydrous ethanol, and a dark blue precursor is obtained after the anhydrous ethanol is completely evaporated; the dark blue precursor is obtained by high-temperature calcination; the mass ratio of the tungsten salt to the urea is 5:1-10:

1.

3. The catalytic material of tungsten suboxide and carbon-supported platinum according to claim 2, characterized in that: The tungsten salt is WCl6.

4. The catalytic material of tungsten suboxide and carbon-supported platinum according to claim 2, characterized in that: The high temperature calcination condition is to increase the temperature to 700°C-800°C at a heating rate of 0.2°C / min-10°C / min under Ar atmosphere and keep the temperature for 3-4 hours.

5. The method for preparing a catalytic material of tungsten suboxide and carbon-supported platinum according to claim 1, characterized in that: The method comprises adding tungsten suboxide to ultrapure water, stirring evenly with ultrasound, then adding platinum salt and XC-72C in sequence, continuing to stir evenly, freeze-drying the obtained dispersion to obtain a black solid; and reducing the black solid at high temperature to obtain Pt-W 18 O 49 / C catalytic material; the mass ratio of the ultrapure water to the tungsten suboxide is 1:10~1:20; the mass ratio of the platinum salt, the tungsten suboxide, and the XC-72C is 1:3~36:5~120.

6. The method for preparing a catalytic material of tungsten suboxide and carbon-supported platinum according to claim 5, characterized in that: The platinum salt is present at a concentration of 10 mg mL -1 of chloroplatinic acid solution.

7. The method for preparing a catalytic material of tungsten suboxide and carbon-supported platinum as claimed in claim 5, characterized in that: The high temperature reduction condition refers to keeping the temperature at 250°C to 350°C for 2 to 4 hours in a mixed atmosphere of H2 and Ar; the volume fraction of H2 in the mixed atmosphere of H2 and Ar is 5% to 10%.

8. The use of a catalytic material of tungsten suboxide and carbon-supported platinum as claimed in claim 1, characterized in that: The catalytic material is used as a cathode catalyst in a proton exchange membrane water electrolyzer in the oxygen evolution reaction of acidic water electrolysis.

Images