Preparation Method and Application of an Ultra-Thin Triangular Ruthenium Nanosheet Catalyst

Abstract

The present invention discloses a preparation method and application of an ultrathin triangular ruthenium nanosheet catalyst, comprising: sequentially adding a ruthenium metal salt, a stabilizer, a first reducing agent, a second reducing agent, and a surfactant and a morphology control agent into a round-bottom flask, and mixing them thoroughly; placing the ultrathin triangular ruthenium nanosheet reaction precursor solution in an oil bath and reacting at a high temperature to obtain ultrathin triangular ruthenium nanosheets, then centrifugally washing the ultrathin triangular ruthenium nanosheets with a first solvent and storing them in the first solvent; dissolving carbon powder in the first solvent, then adding the ultrathin triangular ruthenium nanosheets, mixing them thoroughly, centrifugally separating, and drying to obtain the required ultrathin triangular ruthenium nanosheet catalyst. The preparation process of the present invention is simple, low in cost, and the performance of the catalyst is superior to that of a commercial platinum-carbon catalyst, having good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial synthesis and electrocatalysis, and particularly to a preparation method and application of an ultrathin triangular ruthenium nanosheet catalyst. Background Art

[0002] Currently, the vast majority of hydrogen comes from fossil energy and hydrogen production from industrial by-products. These hydrogen production methods have relatively low costs, but pollution and carbon emissions are still inevitable during the production process. Therefore, electrolysis of water, as a hydrogen production method with high efficiency, no pollution, high purity, and abundant resources (water), has great development potential. In the process of reducing the cost of hydrogen production by electrolysis of water and improving the hydrogen production efficiency, reducing the cost of the catalyst and improving the catalyst performance are key aspects. Traditional platinum-based catalysts are expensive, while ruthenium has certain cost advantages and is thus considered as a substitute for platinum-based cathode catalysts. It has been proven that ruthenium exhibits great potential in the hydrogen evolution reaction. However, due to the limitation of the intrinsic activity, further design is required to replace platinum-based catalysts.

[0003] The huge specific surface area of ultrathin two-dimensional nanosheets provides abundant sites for the adsorption and transfer of reactants. However, due to the non-directional structure of metal bonds, metal atoms tend to form a three-dimensional close-packed structure, and the synthesis of ultrathin two-dimensional nanosheets is extremely challenging. Chinese Patent (Publication No.: CN112643045A) discloses a palladium ruthenium ultrathin nanosheet and its preparation method, which grows palladium ruthenium nanosheets with noble metal palladium as the nucleation site, but it is impossible to grow and form a single ruthenium metal nanosheet. Chinese Patent (Publication No.: CN113059180A) discloses a hollow material composed of highly antioxidant ultrafine ruthenium nanoparticles and its application in the field of electrolysis of water. Its closely packed particle morphology exposes limited active sites, so the catalytic activity is not ideal. Therefore, preparing an ultrathin pure ruthenium nanosheet catalyst and applying it to electrocatalysis has practical application value and challenges. Summary of the Invention

[0004] The purpose of the present invention is to overcome the disadvantages and deficiencies of the prior art, and propose a preparation method and application of an ultrathin triangular ruthenium nanosheet catalyst. The preparation process is simple, the cost is low, and the performance of the catalyst is superior to that of commercial platinum-carbon catalysts, having good application prospects.

[0005] To achieve the above purpose, the technical solution provided by the present invention is: a preparation method of an ultrathin triangular ruthenium nanosheet catalyst, comprising the following steps:

[0006] 1) Prepare a reaction precursor solution of ultrathin triangular ruthenium nanosheets: sequentially add a ruthenium metal salt, a stabilizer, a first reducing agent, a second reducing agent, and a surfactant and a morphology control agent into a round-bottom flask, and mix them evenly.

[0007] 2) Preparation of ultrathin triangular ruthenium nanosheets: Place the reaction precursor solution of ultrathin triangular ruthenium nanosheets in an oil bath and react at a high temperature to obtain ultrathin triangular ruthenium nanosheets. Subsequently, centrifuge and wash the ultrathin triangular ruthenium nanosheets with a first solvent, and store them in the first solvent.

[0008] 3) Preparation of ultrathin triangular ruthenium nanosheet-supported carbon catalyst: Dissolve carbon powder in the first solvent, then add ultrathin triangular ruthenium nanosheets, mix well, centrifuge and separate, and dry to obtain the desired ultrathin triangular ruthenium nanosheet catalyst.

[0009] Preferably, in step 1), the ruthenium metal salt is ruthenium(III) chloride hydrate, ruthenium(III) acetylacetonate, ruthenium(III) nitrate, or ruthenium(II) acetate; the stabilizer is ammonium bromide, ammonium chloride, or ammonium sulfate; the first reducing agent is ascorbic acid, glucose, or ethylene glycol; the second reducing agent and the surfactant are both oleylamine; the morphology control agent is 1-octadecene or polyvinylpyrrolidone PVP, where 10,000 < PVP molecular weight < 100,000.

[0010] Preferably, the mass ratio of the ruthenium metal salt addition amount to the stabilizer is 0.02 - 0.1; the mass ratio of the ruthenium metal salt addition amount to the first reducing agent is 0.02 - 0.15; the mass ratio of the ruthenium metal salt addition amount to the second reducing agent is 0.002 - 0.003; the mass ratio of the ruthenium metal salt addition amount to the morphology control agent is 0.0015 - 0.003.

[0011] Preferably, in step 1), the mixing method is magnetic stirring or ultrasonic treatment for 0.5 - 1 h.

[0012] Preferably, in step 2), the first solvent is water, ketones, alcohols, alkanes, a mixture of water and ketones, a mixture of water and alkanes, or a mixture of alcohols and ketones.

[0013] Preferably, in step 2), the temperature of the oil bath is 140 - 160 °C, the reaction time is 2 - 6 h; the centrifugation speed is 8000 - 12000 rpm, the centrifugation time is 5 - 10 min, and the number of centrifugation and washing times is 3 - 6 times.

[0014] Preferably, in step 3), the carbon powder is Cabot XC-72, Cabot XC-72R, Ketjenblack EC600JD, or Ketjenblack EC300JD.

[0015] Preferably, in step 3), the loading amount of the ultrathin triangular ruthenium nanosheets is 10% - 60%.

[0016] Preferably, in step 3), the mixing method is mechanical stirring for 5 to 24 h or ultrasonic treatment for 1 to 4 h; the drying condition is vacuum drying, the temperature is 40 to 80 °C, and the drying time is 24 to 48 h; the centrifugation speed is 8000 to 12000 rpm, the centrifugation time is 5 to 10 min, and the number of centrifugation washing times is 3 to 6 times.

[0017] The prepared ultrathin triangular ruthenium nanosheet catalyst is used as an electrolytic water cathode hydrogen evolution catalyst, and its performance is superior to that of commercial platinum-carbon catalyst.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] 1. The present invention provides a preparation method of an ultrathin triangular ruthenium nanosheet catalyst. There are few reports on two-dimensional ruthenium nanosheets. The preparation method of the present invention is relatively simple and has a high yield.

[0020] 2. The thickness of the ultrathin triangular ruthenium nanosheet catalyst prepared by the present invention is less than 2 nm, and the lengths of the three sides are all about 15 nm. The product morphology is uniform and the dispersion is good.

[0021] 3. The ultrathin triangular ruthenium nanosheet catalyst prepared by the present invention is used as an electrolytic water cathode hydrogen evolution catalyst, showing superior performance to commercial platinum-carbon catalyst and having good application prospects.

[0022] 4. The present invention uses ruthenium with a relatively low price among precious metals, greatly reducing the cost of precious metal catalysts for hydrogen evolution reactions.

[0023] 5. The production process of the present invention belongs to low-temperature reaction, which can significantly reduce production energy consumption and is convenient for large-scale synthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 One of the TEM images of the ultrathin triangular ruthenium nanosheets prepared in Example 1.

[0025] Figure 2 Another TEM image of the ultrathin triangular ruthenium nanosheets prepared in Example 1.

[0026] Figure 3 Hydrogen evolution polarization curve of the ultrathin triangular ruthenium nanosheet supported carbon catalyst prepared in Example 1 and commercial platinum-carbon catalyst at room temperature and 0.5 M H2SO4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be further described in detail below with reference to the drawings and embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0028] Example 1

[0029] 1) Preparation of the reaction precursor solution of ultrathin triangular ruthenium nanosheets

[0030] Add 10 mg of ruthenium acetylacetonate, 40 mg of ammonium bromide, 35 mg of ascorbic acid, 4 g of oleylamine, and 2.3 g of 1-octadecene into a 25 mL round-bottom flask, and ultrasonicate for 0.5 h to obtain the reaction precursor solution of ultrathin triangular ruthenium nanosheets.

[0031] 2) Preparation of ultrathin triangular ruthenium nanosheets

[0032] Place the reaction precursor solution of ultrathin triangular ruthenium nanosheets prepared in step 1) into an oil bath, react at 150 °C for 4 h, naturally cool to room temperature after the reaction, perform centrifugal separation at a centrifugal speed of 8000 rpm for 5 min, then perform centrifugal washing with cyclohexane solution for 3 times, and finally disperse the product in ethanol and store it refrigerated.

[0033] 3) Preparation of the carbon-supported catalyst of ultrathin triangular ruthenium nanosheets

[0034] Weigh 10 mg of Cabot XC-72R carbon powder and dissolve it in 100 mL of ethanol. Add all the ultrathin triangular ruthenium nanosheets prepared in step 2) into it, stir for 24 h, then perform centrifugal separation at a speed of 8000 rpm for 5 min, repeat 3 times, and place the solid in a vacuum drying oven at 50 °C for drying for 24 h to obtain the carbon-supported catalyst of ultrathin triangular ruthenium nanosheets (abbreviation: ultrathin triangular ruthenium nanosheet catalyst), and the loading amount is 20%.

[0035] The following is the structural morphology characterization and performance test of the catalyst prepared in this example, and the specific situation is as follows:

[0036] a. Structural morphology characterization of the catalyst:

[0037] The image of the ultrathin triangular ruthenium nanosheets was observed by transmission electron microscopy (TEM) (see Figure 1 , Figure 2 shown). The side length of the ultrathin triangular ruthenium nanosheets prepared in this example is 10 - 15 nm, and the thickness is 1.5 - 2.2 nm. It can be observed from the figure that the morphology of the triangular nanosheets is uniform.

[0038] b. Cathodic hydrogen evolution catalytic performance test:

[0039] Using a three-electrode system, in 0.5 M H2SO4, linear scanning was performed at a scanning rate of 5 mV / s from 0 V to -0.6 V (vs RHE) to measure the hydrogen evolution activity of the catalyst. The results are shown in Figure 3 shown. It can be observed from the figure that the catalyst prepared in this example has a current density of 10 mA / cm-2 The overpotential is only 19 mV at a current density of 100 mA / cm -2 The overpotential at a current density of is 109 mV, which is better than that of the commercial 20% platinum-carbon catalyst.

[0040] Unless otherwise specified, the cathode hydrogen evolution activity test method of the catalyst involved in the present invention is the same as the above test method.

[0041] Example 2

[0042] 1) Preparation of the reaction precursor solution of ultrathin triangular ruthenium nanosheets

[0043] Add 20 mg of ruthenium acetylacetonate, 80 mg of ammonium bromide, 70 mg of ascorbic acid, 8 g of oleylamine, and 4.6 g of 1-octadecene into a 50 mL round-bottom flask, and ultrasonicate for 1 h to obtain the reaction precursor solution of ultrathin triangular ruthenium nanosheets.

[0044] 2) Preparation of ultrathin triangular ruthenium nanosheets

[0045] Place the reaction precursor solution of ultrathin triangular ruthenium nanosheets prepared in step 1) into an oil bath, react at 140 °C for 6 h, naturally cool to room temperature after the reaction, perform centrifugal separation, the centrifugal speed is 12,000 rpm, and the time is 10 min. Subsequently, perform centrifugal washing with cyclohexane solution for 3 times. Finally, disperse the product in ethanol and store it refrigerated.

[0046] 3) Preparation of the ultrathin triangular ruthenium nanosheet-supported carbon catalyst

[0047] Weigh 20 mg of Cabot XC-72R carbon powder and dissolve it in 100 mL of ethanol. Add all the ultrathin triangular ruthenium nanosheets prepared in step 2) into it, stir for 24 h, then perform centrifugal separation, the rotation speed is 12,000 rpm, and the time is 10 min. Repeat 3 times. Place the solid in a vacuum drying oven and dry it at 50 °C for 24 h to obtain the ultrathin triangular ruthenium nanosheet-supported carbon catalyst (abbreviation: ultrathin triangular ruthenium nanosheet catalyst), and the loading amount is 20%.

[0048] The following is the structural morphology characterization and performance test of the catalyst prepared in this example, and the specific situation is as follows:

[0049] The morphology of the catalyst prepared in this example is similar to that of the catalyst prepared in Example 1. The overpotential is 20 mV at a current density of 10 mA / cm -2 and the overpotential at a current density of 100 mA / cm -2 is 110 mV, which is 10 mV lower than that of the commercial 20% platinum-carbon catalyst, and is better than the commercial 20% platinum-carbon catalyst.

[0050] Example 3

[0051] 1) Preparation of reaction precursor solution of ultrathin triangular ruthenium nanosheets

[0052] Add 10 mg of ruthenium acetylacetonate, 500 mg of ammonium bromide, 500 mg of ascorbic acid, 5 g of oleylamine, and 6.66 g of 1-octadecene into a 25 mL round-bottom flask, and ultrasonicate for 0.5 h to obtain a reaction precursor solution of ultrathin triangular ruthenium nanosheets.

[0053] 2) Preparation of ultrathin triangular ruthenium nanosheets

[0054] Place the reaction precursor solution of ultrathin triangular ruthenium nanosheets prepared in step 1) into an oil bath, react at 140 °C for 2 h, naturally cool to room temperature after the reaction, perform centrifugal separation at a centrifugal speed of 8000 rpm for 5 min, then perform centrifugal washing with cyclohexane solution for 3 times, and finally disperse the product in ethanol and store it refrigerated.

[0055] 3) Preparation of carbon-supported catalyst of ultrathin triangular ruthenium nanosheets

[0056] Weigh 22 mg of Cabot XC-72R carbon powder and dissolve it in 100 mL of ethanol. Add all the ultrathin triangular ruthenium nanosheets prepared in step 2) into it, stir for 5 h, then perform centrifugal separation at a speed of 8000 rpm for 5 min, repeat 3 times, and then place the solid in a vacuum drying oven and dry at 40 °C for 24 h to obtain a carbon-supported catalyst of ultrathin triangular ruthenium nanosheets (abbreviation: ultrathin triangular ruthenium nanosheet catalyst), with a loading amount of 10%.

[0057] The following is the structural morphology characterization and performance test of the catalyst prepared in this example, and the specific situation is as follows:

[0058] The morphology of the catalyst prepared in this example is similar to that of the catalyst prepared in Example 1. The overpotential is 21 mV at a current density of 10 mA / cm -2 and the overpotential at a current density of 100 mA / cm -2 is 100 mV, which is 20 mV lower than that of the commercial 20% platinum-carbon catalyst, and is superior to the commercial 20% platinum-carbon catalyst.

[0059] Example 4

[0060] 1) Preparation of reaction precursor solution of ultrathin triangular ruthenium nanosheets

[0061] Add 10 mg of ruthenium acetylacetonate, 50 mg of ammonium bromide, 50 mg of ascorbic acid, 3.33 g of oleylamine, and 3.33 g of 1-octadecene into a 25 mL round-bottom flask, and ultrasonicate for 1 h to obtain a reaction precursor solution of ultrathin triangular ruthenium nanosheets.

[0062] 2) Preparation of ultrathin triangular ruthenium nanosheets

[0063] Place the reaction precursor solution of ultrathin triangular ruthenium nanosheets prepared in step 1) into an oil bath and react at 160 °C for 6 h. After the reaction, cool it to room temperature naturally, centrifuge at a speed of 12,000 rpm for 10 min, then wash it by centrifugation with cyclohexane solution for 6 times, and finally disperse the product in ethanol and store it refrigerated.

[0064] 3) Preparation of ultrathin triangular ruthenium nanosheet-supported carbon catalyst

[0065] Weigh 1.6 mg of Cabot XC-72R carbon powder and dissolve it in 50 mL of ethanol. Add all the ultrathin triangular ruthenium nanosheets prepared in step 2) into it, stir for 24 h, then centrifuge at a speed of 12,000 rpm for 10 min, repeat 6 times, and then put the solid into a vacuum drying oven and dry it at 80 °C for 48 h to obtain an ultrathin triangular ruthenium nanosheet-supported carbon catalyst (abbreviation: ultrathin triangular ruthenium nanosheet catalyst), with a loading amount of 60%.

[0066] The following is the structural morphology characterization and performance test of the catalyst prepared in this example above, and the specific situation is as follows:

[0067] The morphology of the catalyst prepared in this example is similar to that of the catalyst prepared in Example 1. The overpotential is 17 mV at a current density of 10 mA / cm -2 and the overpotential at a current density of 100 mA / cm -2 is 92 mV, which is 28 mV lower than that of the commercial 20% platinum-carbon catalyst, and is superior to the commercial 20% platinum-carbon catalyst.

[0068] Example 5

[0069] In this example, except that ruthenium acetate is used as the ruthenium source, other preparation and testing methods are exactly the same as those in Example 1. The overpotential of the catalyst prepared in this example is 19 mV at a current density of 10 mA / cm -2 and the overpotential at a current density of 100 mA / cm -2 is 11 mV lower than that of the commercial 20% platinum-carbon catalyst, and is superior to the commercial 20% platinum-carbon catalyst.

[0070] Example 6

[0071] In this example, except that ruthenium acetate is used as the ruthenium source, other preparation and testing methods are exactly the same as those in Example 2. The electrocatalytic activity of the catalyst prepared in this example is the same as that of the catalyst prepared in Example 3.

[0072] Table 1

[0073]

[0074]

[0075] As can be seen from Table 1 above, the catalyst prepared by the present invention has advantages in morphology. The catalytic performance of the triangular ruthenium nanosheet catalyst is greatly improved compared with that of the conventional particulate catalyst. Moreover, there are few reports on the preparation methods for controlling the nanomorphology of ruthenium at present. The morphologies of most ruthenium-based hydrogen evolution catalysts are particulate. The triangular ruthenium nanosheet catalyst exhibits excellent performance under acidic conditions and has good application prospects, which is worthy of popularization.

[0076] The embodiments of the present invention are merely examples given to clearly illustrate the present invention, rather than limitations on the implementation manners of the present invention. For professionals in the relevant field, based on the above embodiments, other different forms of changes or alterations can be made. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A preparation method of an ultra-thin triangular ruthenium nanosheet catalyst, characterized in that, It includes the following steps: 1) Prepare a reaction precursor solution of ultrathin triangular ruthenium nanosheets: sequentially add ruthenium metal salt, stabilizer, first reducing agent, second reducing agent, and surfactant and morphology control agent into a round-bottom flask, and mix them evenly; The ruthenium metal salt is ruthenium trichloride hydrate, ruthenium acetylacetonate, ruthenium nitrate or ruthenium acetate; the stabilizer is ammonium bromide, ammonium chloride or ammonium sulfate; the first reducing agent is ascorbic acid, glucose or ethylene glycol; the second reducing agent and the surfactant are both oleylamine; the morphology control agent is 1-octadecene or polyvinylpyrrolidone PVP, where 10,000 < PVP molecular weight < 100,000; The mass ratio of the addition amount of the ruthenium metal salt to the stabilizer is 0.02 - 0.1; the mass ratio of the addition amount of the ruthenium metal salt to the first reducing agent is 0.02 - 0.15; the mass ratio of the addition amount of the ruthenium metal salt to the second reducing agent is 0.002 - 0.003; the mass ratio of the addition amount of the ruthenium metal salt to the morphology control agent is 0.0015 - 0.003; 2) Prepare ultrathin triangular ruthenium nanosheets: place the reaction precursor solution of ultrathin triangular ruthenium nanosheets in an oil bath and react at a high temperature to obtain ultrathin triangular ruthenium nanosheets, then use the first solvent to centrifugally wash the ultrathin triangular ruthenium nanosheets and store them in the first solvent; The temperature of the oil bath is 140 - 160 °C, and the reaction time is 2 - 6 h; the rotation speed of centrifugation is 8000 - 12000 rpm, the centrifugation time is 5 - 10 min, and the number of centrifugal washing times is 3 - 6 times; 3) Prepare an ultrathin triangular ruthenium nanosheet-supported carbon catalyst: dissolve carbon powder in the first solvent, then add ultrathin triangular ruthenium nanosheets, mix them evenly, perform centrifugal separation, and dry to obtain the required ultrathin triangular ruthenium nanosheet catalyst.

2. The preparation method of an ultra-thin triangular ruthenium nanosheet catalyst according to claim 1, characterized in that: In step 1), the mixing method is magnetic stirring or ultrasonic treatment for 0.5 - 1 h.

3. The preparation method of an ultra-thin triangular ruthenium nanosheet catalyst according to claim 1, characterized in that: In step 2), the first solvent is water, ketones, alcohols, alkanes, a mixture of water and ketones, a mixture of water and alkanes, or a mixture of alcohols and ketones.

4. The preparation method of an ultra-thin triangular ruthenium nanosheet catalyst according to claim 1, characterized in that: In step 3), the carbon powder is Cabot XC-72, Cabot XC-72R, Ketjenblack EC600JD or Ketjenblack EC300JD.

5. The preparation method of an ultrathin triangular ruthenium nanosheet catalyst according to claim 1, characterized in that: In step 3), the loading amount of the ultrathin triangular ruthenium nanosheets is 10% - 60%.

6. The preparation method of an ultra-thin triangular ruthenium nanosheet catalyst according to claim 1, characterized in that: In step 3), the mixing method is mechanical stirring for 5 - 24 h or ultrasonic treatment for 1 - 4 h; the drying conditions are vacuum drying, the temperature is 40 - 80 °C, and the drying time is 24 - 48 h; the rotation speed of centrifugation is 8000 - 12000 rpm, the centrifugation time is 5 - 10 min, and the number of centrifugal washing times is 3 - 6 times.

7. Use of the ultrathin triangular ruthenium nanosheet catalyst prepared by the method according to claim 1, characterized in that: It is used as a cathode hydrogen evolution catalyst for electrolyzing water.

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