Ruthenium-platinum sub-nano alloy catalyst as well as preparation method and application thereof

Abstract

The invention discloses a ruthenium-platinum sub-nano alloy catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. The ruthenium-platinum sub-nano alloy catalyst provided by the invention comprises ruthenium-platinum alloy, the particle size of the ruthenium-platinum sub-nano alloy catalyst is less than or equal to 10nm. Based on the discovery that ruthenium shows higher alkaline hydrogen evolution activity than platinum under alkaline conditions, ruthenium and platinum are matched to construct the ruthenium-platinum alloy catalyst, respective advantages of ruthenium and platinum can be combined, the loading amount of platinum is reduced, the catalytic activity of alkaline hydrogen evolution reaction and alkaline hydrogen oxidation reaction is remarkably improved, and the catalytic activity of the catalyst is improved. Moreover, the sub-nanometer size provides sufficient active sites for the reaction, and the catalyst has a good application prospect in hydrogen evolution of alkaline electrolytic water or preparation of alkaline hydrogen-oxygen fuel cells.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a ruthenium-platinum sub-nano alloy catalyst and a preparation method and application thereof. Background Art

[0002] Building a hydrogen energy society is a key way to alleviate the energy crisis and climate change. In order to accelerate the transformation of this energy structure, it is necessary not only to develop hydrogen production by water electrolysis, but also to increase research and development efforts on hydrogen-oxygen fuel cells at the hydrogen-using end. Current water electrolysis hydrogen production and hydrogen-oxygen fuel cell devices can be divided into those that react in alkaline and acidic electrolytes. Water electrolysis hydrogen production and hydrogen-oxygen fuel cells in acidic electrolytes have high energy conversion efficiency, but acidic electrolytes are highly corrosive, and catalysts require a large amount of precious metals iridium and rhodium. Water electrolysis hydrogen production and hydrogen-oxygen fuel cells in alkaline electrolytes greatly reduce the corrosion resistance requirements of catalysts and reduce the use of precious metals. However, the kinetics of hydrogen evolution half-reaction and hydrogen oxidation half-reaction in alkaline electrolytes are one to two orders of magnitude lower than those in acidic electrolytes, so the development of efficient catalysts that can be applied to alkaline electrolytes is the current research focus. Summary of the invention

[0003] In order to overcome at least one of the problems existing in the above-mentioned prior art, one of the objects of the present invention is to provide a ruthenium-platinum sub-nano alloy catalyst having good catalytic activity, and being particularly suitable for hydrogen evolution half-reaction and hydrogen oxidation half-reaction under alkaline conditions.

[0004] The second object of the present invention is to provide a method for preparing the above-mentioned ruthenium-platinum sub-nano alloy catalyst.

[0005] The third object of the present invention is to provide an application of the above-mentioned ruthenium-platinum sub-nano alloy catalyst.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a ruthenium-platinum sub-nano alloy catalyst, which comprises a ruthenium-platinum alloy; the particle size of the ruthenium-platinum sub-nano alloy catalyst is ≤10nm.

[0008] Preferably, the particle size of the ruthenium-platinum sub-nano alloy catalyst is 0.5 to 10 nm; more preferably, it is 1 to 9 nm; and even more preferably, it is 3 to 8.5 nm.

[0009] Preferably, the average particle size of the ruthenium-platinum sub-nano alloy catalyst is 1 to 10 nm; more preferably, it is 3 to 9 nm; and even more preferably, it is 4 to 8 nm.

[0010] Preferably, in the ruthenium-platinum alloy, the molar ratio of ruthenium to platinum is (2-7):1; more preferably (3-5):1; further preferably (3.5-4.5):1; and most preferably 4:1.

[0011] Preferably, the ruthenium-platinum sub-nano alloy catalyst also includes a carbon carrier that supports the ruthenium-platinum alloy; further preferably, the carbon carrier includes at least one of carbon black, carbon nanotubes, mesoporous carbon or graphene; in some specific embodiments of the present invention, the carbon carrier is selected from carbon black; more specifically, selected from carbon black XC-72R.

[0012] Preferably, in the ruthenium-platinum sub-nano alloy catalyst, the mass ratio of the ruthenium-platinum alloy to the carbon carrier is 1:(2-6); more preferably, it is 1:(3-5).

[0013] The second aspect of the present invention provides a method for preparing a ruthenium-platinum sub-nano alloy catalyst, comprising the following steps: subjecting a mixed solution containing a ruthenium source, a platinum source and a reducing agent to a chemical liquid phase reduction reaction to obtain the ruthenium-platinum sub-nano alloy catalyst described in the first aspect of the present invention.

[0014] Preferably, the ruthenium source includes a ruthenium salt, a ruthenium complex or a combination thereof; further preferably, the ruthenium source includes at least one of triruthenium dodecacarbonyl, ruthenium acetylacetonate, ruthenium chloride, ruthenium acetate or ruthenium nitrate; in some specific embodiments of the present invention, the ruthenium source is selected from triruthenium dodecacarbonyl.

[0015] Preferably, the platinum source includes a platinum salt, a platinum complex or a combination thereof; further preferably, the platinum source includes at least one of acetylacetonate platinum, chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinite, platinum nitrate or ammonium chloroplatinate; in some specific embodiments of the present invention, the platinum source is selected from acetylacetonate platinum.

[0016] Preferably, the reducing agent comprises at least one of oleylamine, ascorbic acid or formic acid; further preferably, the reducing agent is selected from oleylamine.

[0017] Preferably, the solvent used in the mixed liquid includes at least one of oleylamine, methanol, ethanol or ethylene glycol; further preferably, the solvent used in the mixed liquid is selected from oleylamine.

[0018] Oleylamine is an organic solvent with reducing properties. In the present invention, oleylamine can be used as both a solvent and a reducing agent to achieve a good reduction effect of ruthenium source and platinum source, thereby obtaining a sub-nanometer ruthenium-platinum alloy.

[0019] Preferably, the concentration of the ruthenium source in the mixed solution is 0.001 to 0.05 mol / L; more preferably, it is 0.003 to 0.02 mol / L.

[0020] Preferably, the concentration of the platinum source in the mixed solution is 0.001 to 0.05 mol / L; more preferably, it is 0.003 to 0.02 mol / L.

[0021] Preferably, in the mixed solution, the molar ratio of ruthenium in the ruthenium source to platinum in the platinum source is (2-7):1; more preferably (3-5):1; further preferably (3.5-4.5):1; and most preferably 4:1.

[0022] Preferably, the temperature of the chemical liquid phase reduction reaction is 160-240° C., more preferably 170-230° C., and even more preferably 180-220° C. Non-limiting specific examples include 190° C., 200° C., or 210° C.

[0023] Preferably, the chemical liquid phase reduction reaction time is 1 to 14 hours, more preferably 2 to 13 hours, and even more preferably 3 to 12 hours, and non-limiting specific examples include 4 hours, 6 hours, 8 hours, or 10 hours.

[0024] Preferably, the preparation method further comprises a step of ultrasonically dispersing the mixture before performing the chemical liquid phase reduction reaction.

[0025] Preferably, the temperature of the ultrasonic dispersion is ≤35°C, more preferably 20-35°C, non-limiting specific examples include 22°C, 25°C or 30°C.

[0026] Preferably, the ultrasonic dispersion time is 0.5 to 5 h; more preferably 0.5 to 2 h.

[0027] Preferably, in the preparation method, after performing the chemical liquid phase reduction reaction to obtain a reduction product, the method further comprises the step of loading the reduction product on a carbon carrier.

[0028] In some embodiments of the present invention, the step of loading the reduction product on a carbon carrier is specifically as follows: dispersing the reduction product in an organic solvent to obtain a dispersion; then applying the dispersion on a carbon carrier, and obtaining the ruthenium-platinum sub-nano alloy catalyst after drying.

[0029] Preferably, the organic solvent comprises cyclohexane, ethanol or a combination thereof; further preferably, the organic solvent is selected from cyclohexane.

[0030] The third aspect of the present invention provides a ruthenium-platinum sub-nano alloy catalyst as described in the first aspect of the present invention, or a ruthenium-platinum sub-nano alloy catalyst prepared by the preparation method as described in the second aspect of the present invention, in an alkaline water electrolysis hydrogen evolution reaction or in the preparation of an alkaline hydrogen-oxygen fuel cell.

[0031] The alkaline water electrolysis hydrogen evolution reaction described in the present invention means that the electrolyte used in the water electrolysis hydrogen evolution reaction is selected from alkaline electrolytes; the alkaline hydrogen and oxygen fuel cell means that the electrolyte used in the hydrogen and oxygen fuel cell is selected from alkaline electrolytes.

[0032] The beneficial effects of the present invention are as follows: based on the discovery that ruthenium exhibits stronger alkaline hydrogen evolution activity than platinum under alkaline conditions, the present invention combines ruthenium with platinum to form a ruthenium-platinum alloy catalyst, which can combine the respective advantages of ruthenium and platinum, while reducing the loading amount of platinum, significantly improve the catalytic activity of alkaline hydrogen evolution reaction and alkaline hydrogen oxidation reaction, and the sub-nanometer size provides sufficient active sites for the reaction, and the catalyst of the present invention has good application prospects in alkaline water electrolysis hydrogen evolution or preparation of alkaline hydrogen and oxygen fuel cells. In addition, the preparation method provided by the present invention is based on a chemical liquid phase reduction reaction, and the metal precursor is uniformly dispersed in a solvent and then placed at a certain temperature for reaction. The method has clear steps, is simple, has good repeatability, and is easy to prepare in batches. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a TEM image of the ruthenium-platinum sub-nano alloy catalyst prepared in Example 1 of the present invention.

[0034] Figure 2 This is a particle size distribution diagram of the ruthenium-platinum sub-nano alloy catalyst prepared in Example 1 of the present invention.

[0035] Figure 3 The LSV diagrams of the hydrogen evolution reaction in alkaline water electrolysis of the ruthenium-platinum sub-nano alloy catalysts prepared in Examples 1 to 3 of the present invention and the commercial platinum-carbon catalyst.

[0036] Figure 4 The Tafel slope diagrams of the alkaline water electrolysis hydrogen evolution reaction of the ruthenium-platinum sub-nano alloy catalysts prepared in Examples 1 to 3 of the present invention and the commercial platinum-carbon catalyst.

[0037] Figure 5 It is a polarization curve diagram of the alkaline hydrogen oxidation reaction of the ruthenium-platinum sub-nano alloy catalyst prepared in Example 2 of the present invention and the commercial platinum-carbon catalyst. DETAILED DESCRIPTION

[0038] The content of the present invention is further described in detail below through specific examples. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can all be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0039] It should be noted that, in the following examples, room temperature refers to a temperature not exceeding 35°C, more specifically 20-35°C.

[0040] Example 1

[0041] A ruthenium-platinum sub-nano alloy catalyst is prepared by the following steps:

[0042] (1) Weigh 21 mg of triruthenium dodecacarbonyl and 7.5 mg of platinum acetylacetonate into a glass bottle, add 5 mL of oleylamine as a solvent, and ultrasonically disperse at room temperature for 2 h to obtain a clear, transparent, uniform solution;

[0043] (2) The dispersion obtained in step (1) was sealed with a cover and transferred to a reaction kettle. The temperature was controlled at 200° C. and the insulation time was 6 h, and a black colloidal solution was finally obtained;

[0044] (3) cooling the solution obtained in step (2) to room temperature, washing it several times with a cyclohexane / ethanol mixture, and then dispersing it in cyclohexane for later use;

[0045] (4) The catalyst dispersion obtained in step (3) is added dropwise to the commercial carbon black XC-72R ethanol dispersion, wherein the mass ratio of the catalyst to the commercial carbon black XC-72R is about 1:4, to obtain a ruthenium-platinum sub-nano alloy catalyst supported on the commercial carbon black XC-72R, which is recorded as Ru5Pt1@C.

[0046] Example 2

[0047] A ruthenium-platinum sub-nano alloy catalyst is prepared by the following steps:

[0048] (1) Weigh 21 mg of triruthenium dodecacarbonyl and 10 mg of platinum acetylacetonate into a glass bottle, add 5 mL of oleylamine as a solvent, and ultrasonically disperse at room temperature for 2 h to obtain a clear, transparent, uniform solution;

[0049] (2) The dispersion obtained in step (1) was sealed with a cover and transferred to a reaction kettle. The temperature was controlled at 200° C. and the insulation time was 6 h, and a black colloidal solution was finally obtained;

[0050] (3) The solution obtained in step (2) is cooled to room temperature, washed several times with a cyclohexane / ethanol mixture, and then dispersed in cyclohexane for later use.

[0051] (4) The catalyst dispersion obtained in step (3) is added dropwise to the commercial carbon black XC-72R ethanol dispersion, wherein the mass ratio of the catalyst to the commercial carbon black XC-72R is about 1:4, to obtain a ruthenium-platinum sub-nano alloy catalyst supported on the commercial carbon black XC-72R, which is recorded as Ru4Pt1@C catalyst.

[0052] Example 3

[0053] A ruthenium-platinum sub-nano alloy catalyst is prepared by the following steps:

[0054] (1) Weigh 15 mg of triruthenium dodecacarbonyl and 10 mg of platinum acetylacetonate into a glass bottle, add 5 mL of oleylamine as a solvent, and disperse by ultrasound at room temperature for 2 h to obtain a clear, transparent, uniform solution;

[0055] (2) The dispersion obtained in step (1) was sealed with a cover and transferred to a reaction kettle. The temperature was controlled at 200° C. and the insulation time was 6 h, and a black colloidal solution was finally obtained;

[0056] (3) The solution obtained in step (2) is cooled to room temperature, washed several times with a cyclohexane / ethanol mixture, and then dispersed in cyclohexane for later use.

[0057] (4) The catalyst dispersion obtained in step (3) is added dropwise to the commercial carbon black XC-72R ethanol dispersion, wherein the mass ratio of the catalyst to the commercial carbon black XC-72R is about 1:4, thereby obtaining a ruthenium-platinum sub-nano alloy catalyst supported on the commercial carbon black XC-72R, which is recorded as Ru3Pt1@C catalyst.

[0058] Performance Testing

[0059] 1) Morphology and particle size characterization: Transmission electron microscopy (TEM) images and particle size distribution diagrams of the ruthenium-platinum sub-nano alloy catalysts prepared in Test Examples 1 to 3.

[0060] 2) Alkaline water electrolysis hydrogen evolution performance test: The ruthenium-platinum sub-nano alloy catalysts prepared in Examples 1 to 3 were used for water electrolysis hydrogen evolution reaction under alkaline conditions, and the linear sweep voltammetry (LSV) curve and Tafel slope curve were obtained. (Test conditions: using a rotating disk electrode, a rotation speed of 1600 rpm, and conducting an electrochemical hydrogen evolution reaction test in a 1M potassium hydroxide solution)

[0061] 3) Alkaline hydrogen oxidation reaction performance test: The ruthenium-platinum sub-nano alloy catalyst prepared in Examples 1 to 3 was used for hydrogen oxidation reaction under alkaline conditions, and the polarization curve was obtained by testing. (Test conditions: using a rotating disk electrode, a rotation speed of 1600 rpm, and conducting an electrochemical hydrogen oxidation reaction test in a 0.1 M potassium hydroxide solution)

[0062] Figure 1 This is a TEM image of the ruthenium-platinum sub-nano alloy catalyst prepared in Example 1 of the present invention. As can be seen from the figure, the ruthenium-platinum alloy obtained in Example 1 has a sub-nano size (<10 nm) and the particle size is uniform. Figure 2 The particle size distribution diagram of the ruthenium-platinum sub-nano alloy catalyst prepared in Example 1 of the present invention is shown in the figure. As can be seen from the figure, the particle size of the catalyst in Example 1 is mainly distributed in the range of 4 to 8.5 nm, and the average particle size d m It is 6.07nm.

[0063] Figure 3 LSV curves of the alkaline water electrolysis hydrogen evolution reaction of the ruthenium-platinum sub-nano alloy catalysts and the commercial platinum-carbon catalysts prepared in Examples 1 to 3 of the present invention; Figure 4 The Tafel slope curves of the alkaline water electrolysis hydrogen evolution reaction of the ruthenium-platinum sub-nano alloy catalysts and the commercial platinum-carbon catalysts prepared in Examples 1 to 3 of the present invention are shown. Figure 3 It can be seen that the commercial platinum-carbon catalyst has a -2 The overpotential at the current density is 29 mV, while the ruthenium-platinum sub-nano alloy catalysts of Examples 1 to 3 of the present invention are 10 mA·cm -2 The overpotentials under the current density were 19mV, 12mV, and 17mV, respectively. The ruthenium-platinum sub-nano alloy catalysts of Examples 1 to 3 of the present invention had lower overpotentials and higher catalytic activity. Figure 4 It can be seen that the Tafel slope of the commercial platinum-carbon catalyst is 50.5 mv·dec -1 , while the Tafel slopes of the ruthenium-platinum sub-nano alloy catalysts of Examples 1 to 3 of the present invention are 35.7 mv·dec -1 、32.5mv·dec -1 、35.2mv·dec -1 The ruthenium-platinum sub-nano alloy catalysts of Examples 1 to 3 of the present invention have a lower Tafel slope, can obtain a larger current density at a smaller overpotential, and have a higher catalytic activity.

[0064] Figure 5 The polarization curves of the alkaline hydrogen oxidation reaction of the ruthenium-platinum sub-nano alloy catalyst prepared in Example 2 of the present invention and the commercial platinum-carbon catalyst are shown in FIG. Figure 5It can be seen that compared with the commercial platinum-carbon catalyst, the ruthenium-platinum sub-nano alloy catalyst of Example 2 of the present invention has faster reaction kinetics and better electrochemical performance.

[0065] In summary, the present invention is based on the discovery that ruthenium exhibits stronger alkaline hydrogen evolution activity than platinum under alkaline conditions, and ruthenium and platinum are combined to form a ruthenium-platinum alloy catalyst, which can combine the respective advantages of ruthenium and platinum, while reducing the loading amount of platinum, significantly improve the catalytic activity of alkaline hydrogen evolution reaction and alkaline hydrogen oxidation reaction, and the sub-nanometer size provides sufficient active sites for the reaction. The catalyst of the present invention has good application prospects in alkaline water electrolysis hydrogen evolution or preparation of alkaline hydrogen and oxygen fuel cells. In addition, the preparation method provided by the present invention is based on a chemical liquid phase reduction reaction, and the metal precursor is uniformly dispersed in a solvent and then placed at a certain temperature for reaction. The method has clear steps, is simple, has good repeatability, and is easy to prepare in batches.

Claims

1. A ruthenium-platinum sub-nano alloy catalyst, characterized in that: The ruthenium-platinum sub-nano alloy catalyst comprises a ruthenium-platinum alloy; The particle size of the ruthenium-platinum sub-nano alloy catalyst is ≤10nm.

2. The ruthenium-platinum sub-nano alloy catalyst according to claim 1, characterized in that: In the ruthenium-platinum alloy, the molar ratio of ruthenium to platinum is (2-7):

1.

3. The ruthenium-platinum sub-nano alloy catalyst according to claim 1, characterized in that: The ruthenium-platinum sub-nano alloy catalyst also includes a carbon carrier that supports the ruthenium-platinum alloy; preferably, the carbon carrier includes at least one of carbon black, carbon nanotubes, mesoporous carbon or graphene.

4. A method for preparing a ruthenium-platinum sub-nano alloy catalyst, characterized in that: The following steps are involved: A mixed solution containing a ruthenium source, a platinum source and a reducing agent is subjected to a chemical liquid phase reduction reaction to obtain the ruthenium-platinum sub-nano alloy catalyst as claimed in any one of claims 1 to 3.

5. The preparation method according to claim 4, characterized in that: The ruthenium source includes a ruthenium salt, a ruthenium complex or a combination thereof; preferably, the ruthenium source includes at least one of triruthenium dodecacarbonyl, ruthenium acetylacetonate, ruthenium chloride, ruthenium acetate or ruthenium nitrate; And / or, the platinum source includes a platinum salt, a platinum complex or a combination thereof; preferably, the platinum source includes at least one of acetylacetonate platinum, chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinite, platinum nitrate or ammonium chloroplatinate.

6. The preparation method according to claim 4, characterized in that: The reducing agent comprises at least one of oleylamine, ascorbic acid or formic acid; And / or, the solvent used in the mixed liquid includes at least one of oleylamine, methanol, ethanol or ethylene glycol.

7. The preparation method according to claim 4, characterized in that: The concentration of the ruthenium source in the mixed solution is 0.001 to 0.05 mol / L; And / or, the concentration of the platinum source in the mixed solution is 0.001-0.05 mol / L.

8. The preparation method according to claim 4, characterized in that: The temperature of the chemical liquid phase reduction reaction is 160-240°C; And / or, the chemical liquid phase reduction reaction time is 1 to 14 hours.

9. The preparation method according to claim 4, characterized in that: After the chemical liquid phase reduction reaction is carried out, the method further comprises the step of loading the reduction product on a carbon carrier.

10. Use of the ruthenium-platinum sub-nano alloy catalyst as claimed in any one of claims 1 to 3, or the ruthenium-platinum sub-nano alloy catalyst prepared by the preparation method as claimed in any one of claims 4 to 9 in alkaline water electrolysis hydrogen evolution reaction or preparation of alkaline hydrogen-oxygen fuel cells.

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