RuNi alloy electrocatalyst and preparation method and application thereof

Abstract

The invention discloses a RuNi alloy electrocatalyst and a preparation method and application thereof, and belongs to the technical field of catalysts. Ruthenium acetylacetonate and nickel acetylacetonate are used as precursors, a dispersing agent of polyvinylpyrrolidone is added, the mixture is dissolved in a mixed solvent of benzyl alcohol and aniline, and a mixed solution is obtained; the preparation method comprises the following steps: uniformly stirring, sealing in a reaction kettle, continuously preserving heat at a certain reaction temperature, continuously stirring in the reaction process, and centrifugally drying after the reaction is finished to obtain the RuNi alloy catalyst. The agglomeration of the RuNi alloy nano-particles is effectively prevented, and the nano-particles are ensured to be uniformly dispersed in the synthesis process, so that the catalyst with uniform size and good dispersity is obtained. Through in-situ growth of the Ru element on the surface of the Ni nanostructure, catalytic sites of noble metal are utilized to the maximum extent, excellent conductivity and structural stability of Ni are exerted, the hydrogen evolution effect of the catalyst under the alkaline condition is remarkably improved, and the catalytic activity is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to the preparation of a RuNi alloy electrocatalyst and its application in the hydrogen evolution reaction (HER) of water electrolysis. Background Art

[0002] With the increasing global demand for clean energy and the exacerbation of environmental pollution and global warming caused by the combustion of fossil fuels, the development of efficient and sustainable energy conversion technologies has become particularly important. As an ideal clean energy, the large-scale production and application of hydrogen are of great significance for solving energy crises and environmental problems. In recent years, water electrolysis for hydrogen production has received extensive attention as a green and sustainable hydrogen production method. However, during the hydrogen evolution reaction of water electrolysis under alkaline conditions, a high overpotential limits its efficiency. Therefore, the development of highly active HER electrocatalysts has become an important research hotspot.

[0003] In the field of water electrolysis HER, platinum (Pt)-based catalysts have long occupied a core position and are usually regarded as the preferred catalysts for HER due to their excellent catalytic performance. However, the scarcity and high cost of platinum metal severely restrict its large-scale application. Developing alternative materials with both cost-effectiveness and catalytic activity has become a key bottleneck in the industrialization of hydrogen energy technology. Ruthenium (Ru)-based catalysts are regarded as the most promising alternatives due to their hydrogen binding energy (ΔG H *) similar to that of Pt and a price advantage only one-third that of platinum. Research shows that when ruthenium forms an alloy with transition metals (such as Ni, Co, Fe), the electron synergy effect can significantly optimize the reaction kinetics. However, there are still two major technical challenges in the existing Ru-based alloy systems: ① The noble metal content is relatively high (usually >20 wt%), resulting in a still high material cost; ② Insufficient stability in alkaline media, and Ru dissolution and activity decay are likely to occur during long-term operation. Therefore, developing a simple, efficient, low-cost, and high-performance RuNi alloy and deeply studying its electrocatalytic performance optimization mechanism are of great significance for promoting the development of water electrolysis for hydrogen production technology.

[0004] In view of the above problems, this patent proposes a design strategy for synthesizing RuNi alloy by a thermal solvent method, and realizes the preparation of a highly active and highly stable HER electrocatalyst by optimizing the synthesis conditions. At the same time, while maintaining the catalytic activity, the Ru content is reduced to less than 10 wt%, providing strong support for the development of hydrogen energy technology.

[0005] In summary, the background technical content of this patent mainly focuses on the demand for highly efficient and low-cost electrocatalysts in the hydrogen evolution reaction of water electrolysis and the limitations of the current preparation methods of RuNi alloy catalysts, aiming to propose an innovative solution to meet the needs of industrial applications. Summary of the Invention

[0006] The present invention aims to solve the above existing problems. Therefore, the present invention provides a method for preparing a RuNi alloy electrocatalyst by a one-step hot solvent method and its application in alkaline hydrogen evolution reaction (HER) of water electrolysis.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a RuNi alloy catalyst.

[0009] (1) Using ruthenium acetylacetonate and nickel acetylacetonate as precursors;

[0010] (2) Using polyvinylpyrrolidone as a dispersant;

[0011] (3) Using benzyl alcohol and aniline as solvents;

[0012] The polyvinylpyrrolidone mainly acts as a dispersant, effectively preventing the aggregation of RuNi alloy nanoparticles, ensuring the uniform dispersion of nanoparticles during the synthesis process, and thus obtaining a RuNi alloy nanomaterial with uniform size and good dispersibility.

[0013] In the RuNi alloy, the molar ratio of ruthenium to nickel elements is (1 - 4):50.

[0014] The RuNi alloy nanoparticles grow Ru elements in-situ on the surface of Ni nanostructures, maximizing the use of catalytic sites of precious metals, and at the same time utilizing the excellent electrical conductivity and structural stability of Ni, significantly improving the hydrogen evolution effect and corrosion resistance of the catalyst under alkaline conditions.

[0015] The present invention provides a method for preparing a RuNi alloy, and the specific steps are as follows:

[0016] (1) Using ruthenium acetylacetonate and nickel acetylacetonate as precursors, adding a dispersant of polyvinylpyrrolidone, and dissolving in a mixed solvent of benzyl alcohol and aniline to obtain a mixed solution;

[0017] (2) After stirring evenly, sealing it in a reaction kettle, maintaining a constant temperature at a certain reaction temperature, and continuously stirring during the reaction. After the reaction is completed, centrifuging and drying to obtain the RuNi alloy catalyst.

[0018] In step (1), the molar ratio of ruthenium acetylacetonate to nickel acetylacetonate is (1 - 4):50. Further preferably, the molar ratio is 2:50.

[0019] In step (1), the volume ratio of benzyl alcohol to aniline in the mixed solvent of benzyl alcohol and aniline is (20 - 30):(0.5 - 1.0).

[0020] In step (1), in the mixed solution, for every 30 - 35 ml of the mixed solvent of benzyl alcohol and aniline, 2 - 3 g of the precursors of ruthenium acetylacetonate and nickel acetylacetonate, and 0.2 - 0.3 g of polyvinylpyrrolidone are taken.

[0021] In step (2), during the reaction process, the stirring rate is controlled to be 200 - 600 rpm.

[0022] In step (2), the reaction temperature is 150 - 180 °C.

[0023] In step (2), the reaction time is 6 - 12 h.

[0024] The provided preparation method of the RuNi alloy catalyst optimizes the synthesis conditions, controls the molar ratio between the noble metal Ru and the transition metal Ni. On the premise of maintaining the catalytic activity of the RuNi alloy, the Ru content in the preferably selected RuNi alloy nanoparticles is controlled at 6.6%, effectively reducing the Ru content in the RuNi alloy catalyst to below 10 wt%, providing strong support for the development of hydrogen energy technology.

[0025] Application of the RuNi alloy electrocatalyst of the present invention in the hydrogen evolution reaction of water electrolysis under alkaline conditions.

[0026] This electrocatalyst has excellent HER performance in 1.0 M KOH electrolyte. The electrocatalytic hydrogen evolution reaction is tested in an alkaline solution using a three - electrode system and a rotating disk. The three electrodes are the counter electrode, the reference electrode, and the working electrode. Among them, the working electrode is a glassy carbon electrode, the reference electrode is a mercury / mercuric oxide electrode, and the counter electrode is a carbon rod. And the catalyst loading is 0.28 mg / cm 2 , and the catalytic activity of the RuNi alloy in the HER of water electrolysis is evaluated.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) The present invention synthesizes the RuNi alloy catalyst by a one - step hot - solvent method. The synthesis method is simple and efficient. During the synthesis process, the formation of the nanostructure of RuNi is effectively controlled, improving the catalytic activity of this structure for the hydrogen evolution reaction of water electrolysis.

[0029] (2) The RuNi alloy catalyst provided by the present invention, relying on the interaction between Ru and Ni, in-situ grows Ru elements on the surface of the Ni nanostructure. This catalyst makes full use of the catalytic sites of the noble metal Ru and combines the excellent electrical conductivity and structural stability of Ni, thus showing excellent performance in alkaline HER and having a low overpotential. The obtained RuNi alloy effectively reduces the Ru content in the RuNi alloy catalyst to less than 10 wt%, making it an ideal alternative to platinum-based catalysts and significantly reducing the cost in the process of electrolytic water hydrogen production. Therefore, this catalyst shows great application potential in fields such as electrolytic water alkaline HER. Description of the Drawings

[0030] Figure 1 is the X-ray powder diffraction pattern of Ru2Ni 50 ;

[0031] Figure 2 is Ru1Ni 50 、Ru2Ni 50 、Ru3Ni 50 、Ru4Ni 50 and the linear sweep voltammetry (LSV) curves of commercial 20% Pt / C under alkaline conditions;

[0032] Figure 3 is Ru1Ni 50 、Ru2Ni 50 、Ru3Ni 50 、Ru4Ni 50 and the Tafel slope diagrams of commercial 20% Pt / C under alkaline conditions;

[0033] Figure 4 is Ru2Co 50 、Ru2Cu 50 、Ru2Zn 50 and Ru2Zr 50 under alkaline conditions. Detailed Embodiments

[0034] To illustrate the present invention more clearly, the following further describes the present invention in combination with preferred embodiments and drawings. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0035] Example 1: Preparation of a RuNi Alloy Catalyst

[0036] (1) 0.0637 g of ruthenium acetylacetonate and 2.0553 g of nickel acetylacetonate (the molar ratio of ruthenium acetylacetonate to nickel acetylacetonate is 1:50) were added to a mixture of 200 mg of polyvinylpyrrolidone dissolved in 30 mL of benzyl alcohol and 0.5 mL of aniline.

[0037] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0038] (3) After the reaction was completed, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuum at 60 °C. The obtained product was denoted as Ru1Ni 50 .

[0039] Example 2: Preparation of a RuNi alloy catalyst

[0040] (1) 0.1275 g of ruthenium acetylacetonate and 2.0553 g of nickel acetylacetonate (the molar ratio of ruthenium acetylacetonate to nickel acetylacetonate is 2:50) were added to a mixture of 200 mg of polyvinylpyrrolidone dissolved in 30 mL of benzyl alcohol and 0.5 mL of aniline.

[0041] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0042] (3) After the reaction was completed, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuum at 60 °C. The obtained product was denoted as Ru2Ni 50 .

[0043] Example 3: Preparation of a RuNi alloy catalyst

[0044] (1) 0.1912 g of ruthenium acetylacetonate and 2.0553 g of nickel acetylacetonate (the molar ratio of ruthenium acetylacetonate to nickel acetylacetonate is 3:50) were added to a mixture of 200 mg of polyvinylpyrrolidone dissolved in 30 mL of benzyl alcohol and 0.5 mL of aniline.

[0045] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0046] (3) After the reaction was completed, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuum at 60 °C. The obtained product was denoted as Ru3Ni 50 .

[0047] Example 4: Preparation of a RuNi alloy catalyst

[0048] (1) 0.2550 g of ruthenium acetylacetonate and 2.0553 g of nickel acetylacetonate (the molar ratio of ruthenium acetylacetonate to nickel acetylacetonate is 4:50) were added to a mixture of 30 mL of benzyl alcohol and 0.5 mL of aniline containing 200 mg of polyvinylpyrrolidone.

[0049] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0050] (3) After the reaction, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuo at 60 °C. The obtained product was denoted as Ru4Ni. 50 .

[0051] Analysis of the above Examples 1 - 4

[0052] Figure 1 is the X-ray diffraction pattern of Example 2. It shows that obvious diffraction peaks appeared at 44.5°, 51.8° and 76.4° for Ru2Ni, respectively. These peaks correspond to the (111), (200) and (220) crystal planes of Ni. It was observed that these diffraction peaks matched well with the standard card of Ni (JCPDS#04 - 0850), indicating that these peaks mainly reflected the lattice structure of the Ni component in the Ru2Ni alloy. No obvious Ru diffraction peaks were observed in the XRD pattern, which may be due to the relatively low content of Ru element in the alloy. 50 respectively. These peaks correspond to the (111), (200) and (220) crystal planes of Ni. It was observed that these diffraction peaks matched well with the standard card of Ni (JCPDS#04 - 0850), indicating that these peaks mainly reflected the lattice structure of the Ni component in the Ru2Ni alloy. No obvious Ru diffraction peaks were observed in the XRD pattern, which may be due to the relatively low content of Ru element in the alloy. 50 And no obvious Ru diffraction peaks were observed in the XRD pattern, which may be due to the relatively low content of Ru element in the alloy.

[0053] Figure 2 shows the LSV curves of the prepared RuNi alloys in Examples 1 - 4 for the hydrogen evolution reaction in an alkaline electrolyte (1.0 M KOH electrolyte). As can be seen from the figure, among the catalysts synthesized in Examples 1 - 4, Ru2Ni 50 showed excellent performance under alkaline conditions, with an overpotential of only 41 mV at a current density of 10 mA cm -2 , indicating that this catalyst has the best hydrogen evolution effect, almost comparable to the current commercial Pt / C catalyst. In addition, the Tafel slope, as a key parameter for HER kinetics and catalytic mechanism, was obtained from the LSV curve to draw the Tafel slope graph, as shown in Figure 3 , further proving that Ru2Ni 50 has the best effect among the above catalysts, showing better kinetic characteristics.

[0054] Comparative Example 1: Preparation of a RuCo alloy catalyst

[0055] (1) 0.1275 g of ruthenium acetylacetonate and 2.0733 g of cobalt acetylacetonate were added to a mixture of 200 mg of polyvinylpyrrolidone dissolved in 30 mL of benzyl alcohol and 0.5 mL of aniline.

[0056] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0057] (3) After the reaction was completed, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuo at 60 °C. The obtained product was denoted as Ru2Co 50 .

[0058] Comparative Example 2: Preparation of a RuCu alloy catalyst

[0059] (1) 0.1275 g of ruthenium acetylacetonate and 2.0941 g of copper acetylacetonate were added to a mixture of 200 mg of polyvinylpyrrolidone dissolved in 30 mL of benzyl alcohol and 0.5 mL of aniline.

[0060] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0061] (3) After the reaction was completed, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuo at 60 °C. The obtained product was denoted as Ru2Cu 50 .

[0062] Comparative Example 3: Preparation of a RuZn alloy catalyst

[0063] (1) 0.1275 g of ruthenium acetylacetonate and 2.1088 g of zinc acetylacetonate were added to a mixture of 200 mg of polyvinylpyrrolidone dissolved in 30 mL of benzyl alcohol and 0.5 mL of aniline.

[0064] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0065] (3) After the reaction was completed, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuo at 60 °C. The obtained product was denoted as Ru2Zn 50 .

[0066] Comparative Example 4: Preparation of a RuZr alloy catalyst

[0067] (1) 0.1275 g of ruthenium acetylacetonate and 3.9335 g of zirconium acetylacetonate were added to a mixture of 200 mg of polyvinylpyrrolidone dissolved in 30 mL of benzyl alcohol and 0.5 mL of aniline.

[0068] (2) After magnetic stirring at room temperature for 30 min, it was transferred to a 50 mL autoclave. The sealed autoclave was heated to the reaction temperature of 180 °C and kept at this temperature for 6 h, with continuous stirring during the reaction.

[0069] (3) After the reaction was completed, it was naturally cooled to room temperature. It was centrifugally washed several times with acetone and ethanol and dried in vacuum at 60 °C. The obtained product was denoted as Ru2Zr. 50 .

[0070] For Ru2Co 50 , Ru2Cu 50 , Ru2Zn 50 and Ru2Zr 50 in the above comparative examples were evaluated. As Figure 4 shown, the hydrogen evolution effect of Ru2Ni 50 under alkaline conditions was much higher than that of the catalysts in the above comparative examples. Therefore, the RuNi catalyst prepared in the present invention has more excellent activity.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a RuNi alloy, characterized in that The specific steps are as follows: (1) Using ruthenium acetylacetonate and nickel acetylacetonate as precursors, adding a dispersant of polyvinylpyrrolidone, and dissolving them in a mixed solvent of benzyl alcohol and aniline to obtain a mixed solution; (2) After stirring evenly, sealing it in a reaction kettle, maintaining a constant temperature at a certain reaction temperature, continuously stirring during the reaction process, and centrifuging and drying after the reaction to obtain the RuNi alloy catalyst.

2. The method according to claim 1, characterized in that, In step (1), the molar ratio of ruthenium acetylacetonate to nickel acetylacetonate is (1-4):50; further preferably, the molar ratio is 2:

50.

3. The method according to claim 1, characterized in that, In step (1), the volume ratio of benzyl alcohol to aniline in the mixed solvent of benzyl alcohol and aniline is (20-30):(0.5-1.0).

4. The method according to claim 1, wherein In step (1), in the mixed solution, for every 30-35 ml of the mixed solvent of benzyl alcohol and aniline, it corresponds to 2-3 g of the precursors of ruthenium acetylacetonate and nickel acetylacetonate, and 0.2-0.3 g of polyvinylpyrrolidone is taken.

5. The method according to claim 1, characterized in that, In step (2), the stirring rate is controlled at 200-600 rpm during the reaction process.

6. The method according to claim 1, wherein In step (2), the reaction temperature is 150-180 °C.

7. The method according to claim 1, characterized in that, In step (2), the reaction time is 6-12 h.

8. The RuNi alloy prepared by the method according to any one of claims 1-7.

9. The application of the RuNi alloy prepared by the method according to any one of claims 1-7, as an electrocatalyst in the hydrogen evolution reaction of water electrolysis under alkaline conditions.

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