Preparation of platinum-based multi-metal aerogel and application of platinum-based multi-metal aerogel in electro-catalysis hydrogen evolution

Abstract

The invention discloses a preparation method of platinum-based multi-metal aerogel and application of the platinum-based multi-metal aerogel in an electro-catalysis hydrogen evolution reaction. The method comprises the following steps: firstly, sequentially adding platinum salt and other metal salts into pure water, uniformly mixing, then adding a sodium borohydride solution, uniformly mixing, quickly freezing the reaction solution with liquid nitrogen, melting to obtain wet gel, and then washing and drying the wet gel to obtain the aerogel. The obtained metal aerogel is applied to a hydrogen evolution electrocatalyst and shows excellent catalytic activity under an alkaline condition. The preparation method has the advantages that the synthesis process is simple, convenient and efficient, regulation and optimization of an electronic structure can be realized through interaction among multiple metals, so that the catalytic performance is improved, the porous structure of the aerogel effectively provides a high-speed mass transfer channel, the catalytic activity is improved, and the preparation method is suitable for industrial production. And a solid foundation is laid for wide application of the metal aerogel material in the field of industrial chemical engineering.

Description

Technical Field

[0001] The present invention belongs to the field of aerogels, and relates to the preparation of platinum-based polymetallic aerogels and their electrocatalytic hydrogen evolution applications. Background Art

[0002] With the continuous growth of global energy demand and the exacerbation of environmental pollution problems, the development of clean energy has become the focus of the current energy field. As a clean energy carrier, hydrogen has the advantages of high energy density and no pollution, and has broad application prospects in energy conversion devices such as fuel cells. There are mainly two ways to produce hydrogen: through high-temperature cracking (such as natural gas reforming) and electrolysis of water. The latter uses renewable energy such as solar energy and wind energy to decompose water into hydrogen and oxygen through electrolysis of water. Among them, the hydrogen evolution reaction is one of the key reactions in the electrolysis of water. The efficiency of the electrocatalytic hydrogen evolution reaction is affected by the performance of the catalyst. An efficient electrocatalyst not only needs to have high activity during the reaction process, but also has excellent stability, anti-poisoning properties and low cost. Therefore, the development of new, efficient and low-cost hydrogen evolution reaction catalysts has become the key to the development of hydrogen production technology by electrolysis of water.

[0003] In recent years, researchers have gradually realized that polymetallic catalysts can significantly improve catalytic performance by regulating the interaction of metal elements, electronic structure and optimization of catalytic sites. For example, polymetallic alloys can improve the disadvantages of single-metal catalysts through synergistic effects, lower the energy barrier of the reaction, and thus improve the activity of the hydrogen evolution reaction (DOI: 10.1002 / advs.202200307). In addition, another important feature of polymetallic catalysts is that performance optimization can be achieved through the selection of different metals and component regulation. For example, some metals can provide a strong ability to adsorb hydrogen atoms, while other metals can promote the desorption process of hydrogen molecules from the catalyst surface. Therefore, polymetallic catalysts have good tunability and can exhibit excellent catalytic performance under different reaction conditions.

[0004] As a material with a highly porous structure, aerogel has been widely used in the field of catalysis due to its large specific surface area, low density, high porosity, etc. Aerogel materials can not only provide more reaction sites for catalytic reactions, but also accelerate the transport process of reactants and products, thereby increasing the reaction rate (DOI: 10.1016 / j.matt.2020.10.001). In the hydrogen evolution reaction, the porosity of the aerogel structure helps to improve the electrical conductivity of the catalyst and the exposure of catalytic sites, thus enhancing the catalytic performance. In addition, the light weight and high specific surface area of aerogel provide more design space for the application of catalysts, enabling high catalytic efficiency to be maintained while reducing the amount of material used. Therefore, it can be predicted that through reasonable regulation of the metal composition, multi-metal aerogel can be used as an efficient and stable hydrogen evolution reaction catalyst, providing technical support for the wide application of hydrogen energy. Summary of the Invention

[0005] The present invention provides a preparation method of a platinum-based multi-metal aerogel electrocatalytic material. By regulating the metal composition, the interaction and electronic structure between metal elements are optimized. The prepared metal aerogel material has a large specific surface area, multiple active sites, and excellent catalytic performance. These characteristics enable it to exhibit remarkable catalytic activity and stability in the hydrogen evolution reaction, showing excellent application prospects. This method not only provides a simple and effective way to prepare efficient electrocatalysts, but also lays a solid foundation for the wide application of metal aerogel materials in the industrial chemical field, having positive production significance.

[0006] The object of the present invention is to provide a preparation method of platinum-based multi-metal aerogel and a hydrogen evolution electrocatalyst, and its preparation steps include:

[0007] (1) Add platinum salt and other metal salts to pure water in a certain proportion and mix evenly.

[0008] (2) Add sodium borohydride to the solution obtained in step (1) and mix well.

[0009] (3) Quick-freeze and thaw the solution obtained in step (2) with liquid nitrogen, let it stand for a certain time to obtain a hydrogel. After washing it, perform solvent exchange with tert-butanol.

[0010] (4) Perform freeze-drying treatment on the wet gel obtained in step (3) to obtain a metal aerogel.

[0011] (5) Add the metal aerogel obtained in step (4) to a certain solution and ultrasonicate for 30 - 60 min. Then, dropwise add its uniform dispersion onto the surface of a pre-prepared clean and dry current collector and dry it to serve as a working electrode. Use a Pt sheet as the counter electrode and a Hg / HgO electrode as the reference electrode, and perform electrochemical tests in an electrolyte saturated with a certain gas atmosphere.

[0012] The platinum salt described in step (1) is potassium chloroplatinate or chloroplatinic acid; the other metal salts are one or more of chloroauric acid trihydrate, silver nitrate, potassium tetrachloropalladate, ruthenium trichloride, ammonium hexachlororhodate, iridium trichloride, and ammonium hexachloroosmate.

[0013] The total concentration of the metal salts described in step (1) is 0.1 mM to 1.0 mM; the proportion of each metal salt is 1 to 99%; the mixing method can be stirring, ultrasonic treatment, etc.

[0014] The molar ratio of sodium borohydride to the metal salts described in step (2) is (4 to 20):1.

[0015] The standing time described in step (3) is 12 to 48 h, and the temperature is 10 to 50 °C.

[0016] The washing described in step (4) is specifically: washing with pure water 5 to 10 times. The solvent exchange is specifically: exchanging with tert-butanol 3 to 5 times.

[0017] The freeze-drying described in step (5) is specifically: freezing at -196 °C for 10 min, and then freeze-drying for 4 to 48 h (-80 °C, 5 Pa).

[0018] The solution described in step (6) is a mixed solution of isopropanol and Nafion solution, the concentration of the aerogel is 1 to 5 mg / mL; the current collector is a glassy carbon electrode, a graphite electrode, carbon cloth or carbon paper; the atmosphere is argon or nitrogen; the electrolyte is 1 M potassium hydroxide.

[0019] The beneficial effects of the present invention are reflected in:

[0020] (1) Electronic structure regulation and performance optimization: The multi-metal aerogel catalyst prepared by the method of the present invention can effectively realize the regulation of the electronic structure of the catalyst through the synergistic effect between multi-metals, thereby optimizing its catalytic performance and improving the reaction efficiency.

[0021] (2) Wide applicability: The method provided by the present invention has strong applicability and can be used to prepare multi-metal aerogel catalysts with various different chemical compositions (such as platinum-rhodium-gold (PtRhAu), platinum-ruthenium-gold (PtRuAu), platinum-palladium-ruthenium-rhodium-iridium (PPdRuRhIr), etc.). This feature enables the method to have broad application potential in different catalytic systems.

[0022] (3) Excellent catalytic performance and broad application prospects: The metal aerogel materials prepared by the method of the present invention not only exhibit excellent catalytic performance in the hydrogen evolution reaction, but also far exceed the existing commercial noble metal catalysts in terms of performance. In addition, due to its excellent controllability and tunability, the prepared catalyst can also play a role in other important electrochemical reactions, such as methanol oxidation reaction, ethanol oxidation reaction, oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction, etc. Therefore, the present invention has important practical significance in the fields of energy conversion, new energy development and other related application fields. Description of the Drawings

[0023] Figure 1 is Pt 99 Optical photograph of Ag1 aerogel.

[0024] Figure 2 is Pt 60 Pd 20 Au 20 aerogel and Pt 40 Rh 30 Au 30 Transmission electron microscope image of the aerogel.

[0025] Figure 3 is Pt 40 Rh 30 Au 30 Scanning transmission electron microscope image and element distribution of the aerogel.

[0026] Figure 4 is Pt 25 Rh 25 Ir 25 Au 25 aerogel and Pt 20 Pd 20 Ru 20 Rh 20 Ir 20 Scanning electron microscope image of the aerogel.

[0027] Figure 5 is Pt 33 Pd 33 Au 33 aerogel, Pt 33 Ru 33 Au 33 aerogel, Pt 33 Rh 33 Au 33 Linear sweep voltammetry test chart of the catalytic hydrogen evolution reaction of the aerogel and commercial Pt / C.

[0028] Figure 6 is Pt 33 Pd 33 Au33 Aerogel, Pt 33 Ru 33 Au 33 Aerogel, Pt 33 Rh 33 Au 33 Tafel plot of the catalytic hydrogen evolution reaction of aerogel and commercial Pt / C.

[0029] Figure 7 It is Pt 25 Pd 25 Ir 25 Au 25 Aerogel, Pt 25 Ru 25 Ir 25 Au 25 Aerogel, Pt 25 Rh 25 Ir 25 Au 25 Linear sweep voltammetry test plot of the catalytic hydrogen evolution reaction of aerogel and commercial Pt / C.

[0030] Figure 8 It is Pt 25 Pd 25 Ir 25 Au 25 Aerogel, Pt 25 Ru 25 Ir 25 Au 25 Aerogel, Pt 25 Rh 25 Ir 25 Au 25 Tafel plot of the catalytic hydrogen evolution reaction of aerogel and commercial Pt / C. Specific implementation mode

[0031] The following further describes the present invention in detail with specific embodiments, but the preparation formula, chemical composition of metals, applicable catalytic reactions, etc. used in the present invention are not limited thereto.

[0032] Example 1: Pt 99 Preparation of Ag1 aerogel

[0033] Add 495 μL of an aqueous solution of 10 mM potassium chloroplatinate and 5 μL of an aqueous solution of 10 mM silver nitrate to 4.4 mL of pure water and mix well. Subsequently, inject 100 μL of a 0.2 M sodium borohydride solution into the above solution and mix well. Freeze with liquid nitrogen for 5 min, let stand at room temperature for 5 min, thaw in a water bath at 30 °C for 5 min, and let stand at 10 °C for 24 h. Assemble the obtained gel fragments together to obtain a wet gel. Wash the prepared wet gel with a large amount of water 10 times for a total duration of 3 days to remove possible residues. Exchange with tert-butanol 5 times for a total duration of 1 day. Then, quickly freeze the gel with liquid nitrogen and keep it at -196 °C for about 10 min. Finally, freeze-dry the frozen sample for 48 h to obtain Pt 99 Ag1 aerogel (as Figure 1 shown).

[0034] Example 2: Preparation of Pt 60 Pd 20 Au 20 Aerogel

[0035] Add 30 μL of an aqueous solution of 10 mM potassium chloroplatinate, 10 μL of an aqueous solution of 10 mM potassium tetrachloropalladate, and 10 μL of an aqueous solution of 10 mM chloroauric acid hydrate to 4.9 mL of pure water and mix well. Subsequently, inject 50 μL of a 0.2 M sodium borohydride solution into the above solution and mix well. Freeze with liquid nitrogen for 5 min, let stand at room temperature for 5 min, thaw in a water bath at 30 °C for 5 min, and let stand at 50 °C for 48 h. Assemble the obtained gel fragments together to obtain a wet gel. Wash the prepared wet gel with a large amount of water 5 times for a total duration of 3 days to remove possible residues. Exchange with tert-butanol 3 times for a total duration of 1 day. Then, quickly freeze the gel with liquid nitrogen and keep it at -196 °C for about 10 min. Finally, freeze-dry the frozen sample for 4 h to obtain Pt 60 Pd 20 Au 20 aerogel, Figure 2 where a is its transmission electron microscope image, showing its three-dimensional network structure.

[0036] Example 3: Preparation of Pt 40 Rh 30 Au 30 Aerogel

[0037] Add 100 μL of an aqueous solution of 10 mM chloroplatinic acid, 75 μL of an aqueous solution of 10 mM ammonium hexachlororhodate, and 75 μL of an aqueous solution of 10 mM tetrachloroauric acid hydrate to 4.625 mL of pure water and mix well. Subsequently, inject 125 μL of a 0.2 M sodium borohydride solution into the above solution and mix well. Freeze with liquid nitrogen for 5 min, let stand at room temperature for 5 min, thaw in a water bath at 30 °C for 5 min, and let stand at 30 °C for 36 h. Assemble the obtained gel fragments together to obtain a wet gel. Wash the prepared wet gel 8 times with a large amount of water for a total duration of 3 days to remove possible residues. Exchange with tert-butanol 4 times for a total duration of 1 day. Then, quickly freeze the gel with liquid nitrogen and keep it at -196 °C for about 10 min. Finally, lyophilize the frozen sample for 8 h to obtain a Pt 40 Rh 30 Au 30 aerogel, Figure 2 Figure b is its transmission electron microscope image, and its three-dimensional network structure can be seen. Figure 3 Figure c is its elemental distribution map, and the uniform distribution of its elements can be seen.

[0038] Example 4: Pt 25 Rh 25 Ir 25 Au 25 Preparation of aerogel

[0039] Add 62.5 μL of an aqueous solution of 10 mM chloroplatinic acid, 62.5 μL of an aqueous solution of 10 mM ammonium hexachlororhodate, 62.5 μL of an aqueous solution of 10 mM iridium trichloride, and 62.5 μL of an aqueous solution of 10 mM tetrachloroauric acid hydrate to 4.625 mL of pure water and mix well. Subsequently, inject 125 μL of a 0.2 M sodium borohydride solution into the above solution and mix well. Freeze with liquid nitrogen for 5 min, let stand at room temperature for 5 min, thaw in a water bath at 30 °C for 5 min, and let stand at 20 °C for 24 h. Assemble the obtained gel fragments together to obtain a wet gel. Wash the prepared wet gel 8 times with a large amount of water for a total duration of 3 days to remove possible residues. Exchange with tert-butanol 4 times for a total duration of 1 day. Then, quickly freeze the gel with liquid nitrogen and keep it at -196 °C for about 10 min. Finally, lyophilize the frozen sample for 12 h to obtain a Pt 25 Rh 25 Ir 25 Au 25 aerogel, Figure 4 Figure a is its scanning electron microscope image, and its three-dimensional network structure can be seen.

[0040] Example 5: Pt 20 Pd 20 Ru 20 Rh 20 Ir 20Preparation of Aerogel

[0041] Add 50 μL of an aqueous solution of 10 mM chloroplatinic acid, 50 μL of an aqueous solution of 10 mM potassium tetrachloropalladate, 50 μL of an aqueous solution of 10 mM ruthenium trichloride, 50 μL of an aqueous solution of 10 mM ammonium hexachlororhodate, and 50 μL of an aqueous solution of 10 mM iridium trichloride to 4.625 mL of pure water and mix evenly. Subsequently, inject 125 μL of a 0.2 M sodium borohydride solution into the above solution and mix evenly. Freeze with liquid nitrogen for 5 min, let it stand at room temperature for 5 min, thaw in a water bath at 30 °C for 5 min, and let it stand at 40 °C for 24 h. Assemble the obtained gel fragments together to obtain a wet gel. Wash the prepared wet gel with a large amount of water 10 times for a total duration of 3 days to remove possible residues. Exchange with tert-butanol 3 times for a total duration of 1 day. Then, quickly freeze the gel with liquid nitrogen and keep it at -196 °C for about 10 min. Finally, freeze-dry the frozen sample for 20 h to obtain Pt 20 Pd 20 Ru 20 Rh 20 Ir 20 aerogel, Figure 4 Figure b is its scanning electron microscope image, showing its three-dimensional network structure.

[0042] Example 6: Electrocatalytic Hydrogen Evolution Application of Pt-Based Ternary Metal Aerogel

[0043] Disperse 1.0 mg of the catalyst (Pt 33 Pd 33 Au 33 aerogel, Pt 33 Ru 33 Au 33 aerogel, Pt 33 Rh 33 Au 33 aerogel, commercial Pt / C) in 425 μL of isopropanol and 75 μL of Nafion (1 wt.%) and ultrasonicate for about 30 min to obtain a homogeneous dispersion. Then, drop 10 μL of the dispersion onto the surface of a pre-prepared clean and dry glassy carbon electrode, let it evaporate at room temperature, and form a film after the solvent evaporates. Use it as the working electrode, and use a Pt sheet and a Hg / HgO electrode as the counter electrode and reference electrode respectively. Conduct electrocatalytic hydrogen evolution reaction tests by cyclic voltammetry and linear sweep voltammetry in an electrolyte saturated with argon (1 M potassium hydroxide). Figure 5 is Pt 33 Pd 33 Au 33 , Pt 33 Ru 33 Au 33 , Pt 33 Rh 33 Au33 Linear sweep voltammetry test chart of the catalytic hydrogen evolution reaction of aerogel and commercial Pt / C Figure 6 is its Tafel chart. When the current density reaches 10 mA / cm 2 Pt 33 Ru 33 Au 33 the overpotential is only 38 mV, better than 66 mV of commercial Pt / C, and Pt 33 Ru 33 Au 33 The Tafel slope is 17 mV / dec, better than 50 mV / dec of commercial Pt / C, indicating its better catalytic performance.

[0044] Example 7: Electrocatalytic hydrogen evolution application of Pt-based quaternary metal aerogel

[0045] Disperse 5.0 mg of the catalyst (Pt 33 Pd 33 Au 33 aerogel, Pt 33 Ru 33 Au 33 aerogel, Pt 33 Rh 33 Au 33 aerogel, commercial Pt / C) in 425 μL of isopropanol and 75 μL of Nafion (1 wt.%) and ultrasonicate for about 1 h to obtain a homogeneous dispersion. Then, drop 10 μL of the dispersion onto the surface of a pre-prepared clean and dry carbon paper, let it volatilize at room temperature, and form a film after the solvent evaporates. Use it as the working electrode, and use a Pt sheet and a Hg / HgO electrode as the counter electrode and reference electrode respectively. Perform electrocatalytic tests for hydrogen evolution reactions by cyclic voltammetry and linear sweep voltammetry in an electrolyte saturated with argon (1 M potassium hydroxide). Figure 7 is Pt 25 Pd 25 Ir 25 Au 25 , Pt 25 Ru 25 Ir 25 Au 25 , Pt 25 Rh 25 Ir 25 Au 25 Linear sweep voltammetry test chart of the catalytic hydrogen evolution reaction of aerogel and commercial Pt / C Figure 8 is its Tafel chart. When the current density reaches 10 mA / cm 2 Pt 25 Rh 25 Ir 25 Au 25The overpotential is only 32 mV, which is better than 66 mV of commercial Pt / C, and Pt 33 Ru 33 Au 33 The Tafel slope is 13 mV / dec, which is better than 50 mV / dec of commercial Pt / C, indicating its better catalytic performance.

[0046] 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 within the protection scope of the present invention.

Claims

1. Preparation of platinum-based polymetallic aerogel and its application in electrocatalytic hydrogen evolution, characterized in that, It includes the following steps: (1) Add platinum salts and other metal salts into pure water in a certain proportion and mix evenly. (2) Add sodium borohydride into the solution obtained in step (1) and mix well. (3) Quick-freeze and melt the solution obtained in step (2) with liquid nitrogen, let it stand for a certain time to obtain a hydrogel, wash it, and then conduct solvent exchange with tert-butanol. (4) Conduct freeze-drying treatment on the wet gel obtained in step (3) to obtain a metal aerogel.

2. The preparation method according to claim 1, wherein The platinum salt described in step (1) is potassium chloroplatinate or chloroplatinic acid; the other metal salts are one or more of chloroauric acid trihydrate, silver nitrate, potassium tetrachloropalladate, ruthenium trichloride, ammonium hexachlororhodate, iridium trichloride, ammonium hexachloroosmate.

3. The preparation method according to claim 1, wherein The total concentration of the metal salts described in step (1) is 0.1 mM to 1.0 mM; the proportion of each metal salt is 1 to 99%; the mixing method can be stirring, ultrasonic treatment, etc.

4. The preparation method according to claim 1, wherein The molar ratio of sodium borohydride to the metal salts described in step (2) is (4 to 20):

1.

5. The preparation method according to claim 1, characterized in that, The standing time described in step (3) is 12 to 48 h, and the temperature is 10 to 50 °C.

6. The preparation method according to claim 1, wherein, The washing described in step (4) is specifically: wash with pure water 5 to 10 times. The solvent exchange is specifically: exchange with tert-butanol 3 to 5 times.

7. The preparation method according to claim 1, wherein The freeze-drying described in step (5) is specifically: freeze at -196 °C for 10 min, and then conduct freeze-drying for 4 to 48 h (-80 °C, 5 Pa).

8. A platinum-based polymetallic aerogel, characterized in that, The metal aerogel material obtained by the preparation method according to claims 1 to 7.

9. The platinum-based multi-metal aerogel obtained by the preparation method according to claims 1 to 7 is used as an excellent electrocatalytic hydrogen evolution reaction catalyst.

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