Alloy catalyst and preparation method and application thereof

Abstract

The invention provides an alloy catalyst as well as a preparation method and application thereof. Wherein the alloy catalyst component comprises copper, platinum and ruthenium; wherein the alloy catalyst is of a nanotube structure, according to the preparation method, the components of the alloy catalyst can be accurately regulated and controlled by changing the proportion of a metal precursor, the trimetal nanotube catalyst with uniform distribution of copper, platinum and ruthenium and regular morphology is prepared, and the catalyst is a good electrocatalyst.

Description

Technical Field

[0001] The invention belongs to the field of catalyst preparation, and in particular relates to a method for preparing a tri-metal nanotube catalyst. Background Art

[0002] In the process of human progress and technological development, the exploitation and use of fossil resources has led to the production of a large amount of greenhouse gases, causing serious harm to the environment. At the same time, with the gradual reduction of fossil resources, humans are in urgent need of finding more sustainable energy sources. Hydrogen energy has high hopes as a new energy source due to its advantages such as high energy density, abundant sources, and only water as a combustion product. The sources of hydrogen are diverse, among which the method of producing hydrogen by electrolysis of water has attracted widespread attention due to its high efficiency, no need to consume fossil energy, and high product purity. At present, precious metals represented by platinum have excellent performance as catalytic materials in the electrolysis of water hydrogen evolution reaction, but high cost and low reserves are the main obstacles to the large-scale application of this technology. Therefore, the development of electrocatalysts with high hydrogen production efficiency and low price is a research hotspot in the field of catalysis.

[0003] In recent years, although non-precious metal-based materials have performed well in the hydrogen evolution reaction, precious metal-based materials still have a leading position in the hydrogen evolution reaction due to their optimal interaction with reaction intermediates. Combining precious metals with non-precious metals to form a special structure is a common method for developing highly active and cost-effective catalysts. However, due to the complexity of the synthesis method, there are still few reports of this type. Therefore, the synthesis of a catalyst with a tri-metallic nanotube structure can expose more active sites and highly active crystal faces, which is beneficial to improving the hydrogen evolution performance of the electrocatalyst and has important practical significance. Summary of the invention

[0004] In view of the fact that there are few reports on precious metal and non-precious metal synthesis catalysts in the prior art, the present invention provides an alloy catalyst and a preparation method and application thereof. The alloy catalyst is a tri-metal nanotube catalyst, and the tri-metal nanotube catalyst is a platinum ruthenium copper nanotube catalyst, which is a good electrocatalyst. The preparation method can accurately control the components of the alloy catalyst by changing the ratio of metal precursors to prepare a tri-metal nanotube catalyst with uniform distribution and neat morphology.

[0005] The first aspect of the present invention provides an alloy catalyst, wherein the alloy catalyst components include copper, platinum and ruthenium; wherein the alloy catalyst is a nanotube structure; the surface of the nanotube is rough and has a large number of nanoparticles; the three metals of copper, platinum and ruthenium are evenly distributed in the nanotube, and the rough nanotube surface increases the number of active sites and the attachment area, which is beneficial to enhancing the catalytic activity.

[0006] In some embodiments of the present invention, the copper accounts for 70-80% by weight of the alloy catalyst, preferably 75%, the mass fraction of platinum is 18%, and the mass fraction of ruthenium is 7%.

[0007] In some embodiments of the present invention, the inner diameter of the nano-tubular structure alloy catalyst is 80-100 nanometers, and the appropriate nano-size provides a large number of active sites for the hydrogen evolution reaction;

[0008] The second aspect of the present invention provides a method for preparing the alloy catalyst according to the first aspect, comprising the following steps:

[0009] S1. Providing a mixed solution A containing copper, nickel and a surfactant;

[0010] S2. The mixed solution A is subjected to a multi-step centrifugal treatment to obtain copper nanowires, and a solution B containing copper nanowires is prepared; preferably, the solvent of the solution B is ethanol;

[0011] S3. Providing a mixed solution C containing platinum and ruthenium;

[0012] S4. Mixing the solution B and the solution C to obtain a solution D;

[0013] S5. The solution D is subjected to a multi-step centrifugal treatment to obtain platinum ruthenium copper nanowires, and a solution E containing platinum ruthenium copper nanowires is prepared; preferably, the solvent of the solution E is ethanol;

[0014] S6. After adding an acidic reagent to the solution E, the solution is stirred, centrifuged, washed and dried to obtain platinum ruthenium copper nanotubes.

[0015] In some embodiments of the present invention, in step S1, the preparation of the mixed solution A comprises the following steps:

[0016] S101. Under an inert gas atmosphere, a copper precursor, a nickel precursor and a surfactant are dissolved in an organic solvent at a temperature of 60-90° C. and stirred for 30-90 min; preferably, the temperature is 80° C. and the time is 45 min to ensure that the solvent is in a liquid state and is conducive to the dissolution and uniform mixing of the precursor and the surfactant; preferably, the inert gas is nitrogen or argon;

[0017] S102. After heating and stirring, solution A can be obtained.

[0018] In some embodiments of the present invention, in step S101, the copper precursor is copper acetylacetonate; the nickel precursor is nickel chloride hexahydrate; the surfactant is dimethyl dioctadecyl ammonium chloride; and the organic solvent is oleylamine;

[0019] In some embodiments of the present invention, in step S102, the heating temperature is 170-190°C, preferably 185°C, which is conducive to the reaction and prevents overheating and decomposition of oleylamine; the stirring time is 200-300min, preferably 300min, which helps to carry out a thorough reaction.

[0020] In some embodiments of the present invention, in step S3, the preparation of the mixed solution C comprises the following steps:

[0021] Under an inert gas atmosphere, at a temperature of 85-90° C., a platinum precursor and a ruthenium precursor are dissolved in an organic solvent and stirred for 30-50 minutes to obtain a solution C;

[0022] Preferably, the inert gas is nitrogen or argon;

[0023] Preferably, the platinum precursor is selected from any one of potassium hexachloroplatinate, platinum acetylacetonate, and potassium tetrachloroplatinate, more preferably potassium hexachloroplatinate;

[0024] Preferably, the ruthenium precursor is anhydrous ruthenium chloride;

[0025] Preferably, the organic solvent is 1-octadecene, and the solvent volume is 8-10 mL, so that the dissolved precursor is maintained at an appropriate mass concentration to facilitate the reaction.

[0026] In some embodiments of the present invention, in step S4, the preparation of the mixed solution D comprises the following steps:

[0027] The solution B is added to the solution C, and after stirring at 85-90° C. for 60-90 min, the temperature is raised to 170-190° C. and kept warm for 220-260 min to obtain a solution D.

[0028] In some embodiments of the present invention, in steps S2 and S5, the multi-step centrifugation includes: first centrifugation with a mixed solvent, and then washing centrifugation, wherein the washing centrifugation is: ultrasonically dispersing the solid product obtained after the mixed solvent centrifugation in the mixed solvent, centrifugally separating, pouring off the supernatant, and repeating the operation; multiple washing centrifugations in S5 can disperse the platinum ruthenium copper nanowires into solution E;

[0029] Preferably, the mixed solvent is a mixed solution of n-hexane and ethanol;

[0030] Preferably, the mixed solvent is centrifuged at 6000-9000 rpm for 5-8 min.

[0031] Preferably, the washing centrifugation process is repeated twice;

[0032] Preferably, the ultrasonic dispersion conditions are: 40%-80% of 400W power, ultrasonic for 1-5 min.

[0033] In some embodiments of the present invention, in step S6, the acidic reagent is glacial acetic acid; the stirring time is 0.5-1.5h; the centrifugal condition is 6000-9000rpm, the time is 5-8min; the drying equipment is a vacuum drying oven;

[0034] Preferably, the glacial acetic acid is 0.07-0.35 mg / mL;

[0035] Preferably, the temperature in the vacuum drying oven is 35-60° C., and the vacuum degree is 0.08-0.1 MPa.

[0036] The third aspect of the present invention provides use of the alloy catalyst described in the first aspect or the alloy catalyst prepared by the method described in the second aspect in a hydrogen evolution reaction by electrolysis of water.

[0037] The present invention has the following advantages:

[0038] The alloy catalyst of the present invention is a platinum ruthenium copper nanotube catalyst. The nanotube surface is rough and has a large number of nanoparticles. The three metals of copper, platinum and ruthenium are evenly distributed in the nanotube. The rough nanotube surface increases the number of active sites and the attachment area, which is conducive to enhancing the catalytic activity.

[0039] The preparation method of the present invention adopts a wet chemical method, first synthesizing copper nanowires, obtaining platinum ruthenium copper trimetallic nanowires (PtRuCu trimetallic nanowires) through secondary oil phase synthesis, and then stirring and acid washing with an acidic reagent to obtain a platinum ruthenium copper nanotube catalyst (PtRuCu trimetallic nanotube catalyst). The acidic reagent is glacial acetic acid.

[0040] The present invention changes the amount of added platinum and ruthenium metal precursors to accurately control the composition of the platinum ruthenium copper nanotube catalyst. TEM, HAADF-STEM and line scan tests confirm the tubular hollow structure of the ruthenium copper nanotube catalyst. According to the EDX element distribution map and XRD results, it is concluded that platinum and copper oxide in the platinum ruthenium copper nanotube catalyst exist in crystalline form, and XPS confirms that ruthenium exists in an amorphous structure. The special tri-metal nanotube structure has potential application prospects in the electrocatalytic hydrogen evolution reaction.

[0041] The present invention washes and centrifuges for many times, disperses the obtained platinum ruthenium copper nanowires in ethanol to obtain solution E; adds a certain amount of glacial acetic acid to solution E, stirs for a period of time, centrifuges and washes, and vacuum dries to obtain platinum ruthenium copper nanotubes. The trimetallic nanotube catalyst obtained by the present invention has a uniform morphology and is a good electrocatalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a transmission electron microscope image of the sample obtained in Example 1;

[0043] Figure 2 This is a high-angle annular dark field image of the sample obtained in Example 1;

[0044] Figure 3 This is the elemental analysis diagram of the sample obtained in Example 1;

[0045] Figure 4 This is a line scan test analysis diagram of the sample obtained in Example 1;

[0046] Figure 5 This is the X-ray diffraction pattern of the sample obtained in Example 1;

[0047] Figure 6 The Pt element X-ray photoelectron spectrum of the sample obtained in Example 1;

[0048] Figure 7 The Ru element X-ray photoelectron spectrum of the sample obtained in Example 1;

[0049] Figure 8 X-ray photoelectron spectrum of Cu element of the sample obtained in Example 1;

[0050] Fig. 9 This is a transmission electron microscope image of the sample obtained in Example 2;

[0051] Fig.10 This is a transmission electron microscope image of the sample obtained in Example 3;

[0052] Fig.11 The electrolytic water hydrogen evolution performance diagram of Examples 1, 2, and 3;

[0053] Fig.12 This is a transmission electron microscope image of the sample obtained in Comparative Example 1;

[0054] Fig.13 This is a transmission electron microscope image of the sample prepared in Comparative Example 2. DETAILED DESCRIPTION

[0055] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. It should also be understood that the method steps and data related thereto involved in this embodiment do not exclude the combination of other method steps and other data ratios that can be inserted in the middle, and the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values, and will also be regarded as the scope of implementation of the present invention.

[0056] The equipment and raw materials used in the examples are as follows:

[0057] Copper acetylacetonate (98%), nickel chloride hexahydrate (98%), dimethyldioctadecyl ammonium chloride (97%), potassium hexachloroplatinate, anhydrous ruthenium chloride, oleylamine (80-90%), 1-octadecene (80-90%), SZCL-2 intelligent temperature-controlled magnetic stirrer, three-necked flask, centrifuge.

[0058] Example 1

[0059] 1) 0.2094 g of copper acetylacetonate, 0.0951 g of nickel chloride hexahydrate and a surfactant were placed in 8 mL of oleylamine, and stirred at 80 ° C for 50 min in a nitrogen atmosphere until the solution was uniformly mixed;

[0060] 2) raising the temperature to 185° C. and maintaining it for 220 min to obtain solution A;

[0061] 3) centrifuging solution A with a mixed solution of n-hexane and ethanol to obtain solid copper nanowires, then washing and centrifuging the mixed solution twice, dispersing the finally obtained copper nanowires into an ethanol solution to obtain solution B for standby use;

[0062] 4) Under a nitrogen atmosphere, 24.3 mg of potassium hexachloroplatinate and 10.4 mg of anhydrous ruthenium chloride (molar ratio of 1:1 and total molar amount of 0.1 mmol) were uniformly dissolved in 8 mL of 1-octadecene, and stirred at 85-90° C. for 30-50 min to obtain a solution C;

[0063] 5) Add solution B to solution C and continue stirring at 85-90°C for 60 min to remove the ethanol solvent;

[0064] 6) raising the temperature to 175° C. and maintaining it for 220 min to obtain solution D;

[0065] 7) centrifuging solution D with a mixed solution of n-hexane and ethanol to obtain solid product PtRuCu nanowires, then washing and centrifuging the mixed solution twice, and dispersing the finally obtained PtRuCu nanowires in an ethanol solution to obtain solution E;

[0066] 8) Add 5 mL of glacial acetic acid to solution E, stir for 1 hour, and then centrifuge to obtain an acid-washed product, then wash with an ethanol solution until neutral, and vacuum dry in a vacuum drying oven to obtain PtRuCu nanotubes.

[0067] Figure 1 This is a transmission electron microscope image of the tri-metal platinum ruthenium copper nanotube (precious metal molar ratio Pt:Ru=1:1) obtained in Example 1. It can be seen that the tri-metal nanotube structure has a rough surface;

[0068] Figure 2This is a high-angle annular dark field image of the tri-metal platinum ruthenium copper nanotube (noble metal molar ratio Pt:Ru=1:1) obtained in Example 1;

[0069] Figure 3 This is the elemental analysis diagram of the tri-metal platinum ruthenium copper nanotubes (precious metal molar ratio Pt:Ru=1:1) prepared in Example 1;

[0070] Figure 4 This is a line scan test analysis diagram of the three-metal platinum ruthenium copper nanotubes (precious metal molar ratio Pt:Ru=1:1) prepared in Example 1;

[0071] Figure 5 The X-ray diffraction pattern of the tri-metal platinum ruthenium copper nanotubes (precious metal molar ratio Pt:Ru=1:1) prepared in Example 1;

[0072] Figure 6 The Pt element X-ray photoelectron spectrum of the trimetallic platinum-ruthenium-copper nanotubes (precious metal molar ratio Pt:Ru=1:1) prepared in Example 1;

[0073] Figure 7 The Ru element X-ray photoelectron spectrum of the trimetallic platinum ruthenium copper nanotubes (precious metal molar ratio Pt:Ru=1:1) prepared in Example 1;

[0074] Figure 8 The Cu element X-ray photoelectron spectrum of the tri-metal platinum ruthenium copper nanotubes (precious metal molar ratio Pt:Ru=1:1) prepared in Example 1;

[0075] Example 2

[0076] Example 1 was repeated, except that in step 4), the amounts of potassium hexachloroplatinate and anhydrous ruthenium chloride were 16 mg and 13.9 mg, respectively (the molar ratio was 1:2 and the total molar amount was the same as in Example 1).

[0077] Fig. 9 This is a transmission electron microscope image of the tri-metal platinum ruthenium copper nanotube (precious metal molar ratio Pt:Ru=1:2) prepared in Example 2, proving that it is a hollow nanotube structure with a rough surface.

[0078] Example 3

[0079] Example 1 was repeated, except that in step 4), the amounts of potassium hexachloroplatinate and anhydrous ruthenium chloride were 32.6 mg and 6.8 mg, respectively (the molar ratio was 2:1 and the total molar amount was the same as in Example 1).

[0080] Fig.10 This is a transmission electron microscope image of the tri-metal platinum ruthenium copper nanotube (precious metal molar ratio Pt:Ru=2:1) ​​prepared in Example 3, proving that it is a hollow nanotube structure with a rough surface.

[0081] Fig.11 The performance of hydrogen evolution in water electrolysis in alkaline environment is compared between Example 1, Example 2, and Example 3 and commercial Pt / C catalyst. It can be seen that the three-metal nanotubes with different ratios of precious metals all show better hydrogen evolution activity than commercial Pt / C.

[0082] Comparative Example 1

[0083] Example 1 was repeated, with the only difference being that in step 4), the amount of potassium hexachloroplatinate was 50 mg, the amount of anhydrous ruthenium chloride was 0 mg, and the total molar amount was the same as that in Example 1.

[0084] Fig.12 This is a transmission electron microscope image of the PtCu nanotubes prepared in this comparative example.

[0085] Comparative Example 2

[0086] Example 1 was repeated, with the only difference being that in step 4), the amount of potassium hexachloroplatinate was 0 mg, the amount of anhydrous ruthenium chloride was 20 mg, and the total molar amount was the same as that in Example 1.

[0087] Fig.13 This is a transmission electron microscope image of the RuCu nanotubes prepared in this comparative example.

[0088] In summary, in the preparation method of a tri-metallic nanotube catalyst of the present invention, the temperature, reaction atmosphere, solution volume, amount of metal precursor, etc. are coordinated and cooperated with each other to form a complete technical solution, so that the tri-metallic nanotube catalyst required by the present invention can be prepared.

[0089] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. An alloy catalyst, wherein the alloy catalyst components include copper, platinum and ruthenium; wherein: The alloy catalyst is a nanotubular structure; preferably, the copper accounts for 70-80% of the weight of the alloy catalyst, preferably 75%, the mass fraction of platinum is 18%, and the mass fraction of ruthenium is 7%; preferably, the inner diameter of the nanotubular structure alloy catalyst is 80-100 nanometers.

2. A method for preparing the alloy catalyst as claimed in claim 1, comprising the following steps: S1. Providing a mixed solution A containing copper, nickel and a surfactant; S2. The mixed solution A is subjected to a multi-step centrifugal treatment to obtain copper nanowires, and a solution B containing copper nanowires is prepared; preferably, the solvent of the solution B is ethanol; S3. Providing a mixed solution C containing platinum and ruthenium; S4. Mixing the solution B and the solution C to obtain a solution D; S5. The solution D is subjected to a multi-step centrifugal treatment to obtain platinum ruthenium copper nanowires, and a solution E containing platinum ruthenium copper nanowires is prepared; preferably, the solvent of the solution E is ethanol; S6. After adding an acidic reagent to the solution E, the solution is stirred, centrifuged, washed and dried to obtain platinum ruthenium copper nanotubes.

3. The preparation method according to claim 2, characterized in that: In step S1, the preparation of the mixed solution A comprises the following steps: S101. Under an inert gas atmosphere, a copper precursor, a nickel precursor and a surfactant are dissolved in an organic solvent at a temperature of 60-90° C. and stirred for 30-90 min; preferably, the temperature is 80° C. and the time is 45 min to ensure that the solvent is in a liquid state and is conducive to the dissolution and uniform mixing of the precursor and the surfactant; preferably, the inert gas is nitrogen or argon; S102. After heating and stirring, solution A can be obtained.

4. The preparation method according to claim 3, characterized in that: In step S101, the copper precursor is copper acetylacetonate; the nickel precursor is nickel chloride hexahydrate; the surfactant is dimethyl dioctadecyl ammonium chloride; and the organic solvent is oleylamine.

5. The preparation method according to claim 3, characterized in that: In step S102, the heating temperature is 170-190°C, preferably 185°C, which is conducive to the reaction and prevents overheating and decomposition of oleylamine; the stirring time is 200-300min, preferably 300min, which is conducive to a thorough reaction.

6. The preparation method according to claim 2, characterized in that: In step S3, the preparation of the mixed solution C comprises the following steps: Under an inert gas atmosphere, at a temperature of 85-90° C., a platinum precursor and a ruthenium precursor are dissolved in an organic solvent and stirred for 30-50 minutes to obtain a solution C; Preferably, the inert gas is nitrogen or argon; Preferably, the platinum precursor is selected from any one of potassium hexachloroplatinate, platinum acetylacetonate, and potassium tetrachloroplatinate, more preferably potassium hexachloroplatinate; Preferably, the ruthenium precursor is anhydrous ruthenium chloride; Preferably, the organic solvent is 1-octadecene, and the solvent volume is 8-10 mL, so that the dissolved precursor is maintained at an appropriate mass concentration to facilitate the reaction.

7. The preparation method according to claim 2, characterized in that: In step S4, the preparation of the mixed solution D comprises the following steps: The solution B is added to the solution C, and after stirring at 85-90° C. for 60-90 min, the temperature is raised to 170-190° C. and kept warm for 220-260 min to obtain a solution D.

8. The preparation method according to claim 2, characterized in that: In steps S2 and S5, the multi-step centrifugation includes: first centrifugation with a mixed solvent, and then washing centrifugation, wherein the washing centrifugation is: ultrasonically dispersing the solid product obtained after the mixed solvent centrifugation in the mixed solvent, centrifugally separating, discarding the supernatant, and repeating the operation; Preferably, the mixed solvent is a mixed solution of n-hexane and ethanol; Preferably, the mixed solvent is centrifuged at 6000-9000 rpm for 5-8 min. Preferably, the washing centrifugation process is repeated twice; Preferably, the ultrasonic dispersion conditions are: 40%-80% of 400W power, ultrasonic for 1-5 min.

9. The preparation method according to claim 2, characterized in that: In step S6, the acidic reagent is glacial acetic acid; the stirring time is 0.5-1.5h; the centrifugal condition is 6000-9000rpm, the time is 5-8min; the drying equipment is a vacuum drying oven; Preferably, the glacial acetic acid is 0.07-0.35 mg / mL; Preferably, the temperature in the vacuum drying oven is 35-60° C., and the vacuum degree is 0.08-0.1 MPa.

10. Use of the alloy catalyst according to claim 1 or the alloy catalyst prepared by the method according to any one of claims 2 to 9 in hydrogen evolution reaction by electrolysis of water.

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