Electrolytic acid seawater hydrogen evolution catalyst based on platinum-cobalt alloy / carbon nanotube composite structure and preparation method thereof

Abstract

A hydrogen evolution catalyst for acidic seawater electrolysis based on a platinum-cobalt alloy / carbon nanotube composite structure and its preparation method are disclosed, belonging to the field of nanomaterials and catalysis technology. The catalyst consists of a platinum-cobalt alloy / carbon nanotube composite layer supported on a porous conductive substrate, with a platinum-cobalt metal solid solution uniformly anchored on the surface of acidified carbon nanotubes. The method involves mixing platinum acetylacetonate, cobalt acetylacetonate, and acidified carbon nanotubes, followed by solvent-free microwave pyrolysis under an argon atmosphere to obtain a platinum-cobalt alloy / carbon nanotube composite powder in one step. This powder is then drop-coated onto a porous conductive substrate and electrochemically activated to obtain an integral composite electrode catalyst. This invention enables precise control of the catalyst structure and composition; it features low noble metal loading, a simple and environmentally friendly preparation process; and effectively overcomes the problems of easy deactivation and insufficient stability of traditional platinum-based catalysts in acidic media. It exhibits excellent hydrogen evolution activity and long-term stability under high-temperature, high-current-density electrolysis conditions in acidic seawater.

Description

Technical Field

[0001] This invention belongs to the fields of nanomaterials, electrochemical energy and catalysis technology, and relates to an electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure and its preparation method. Background Technology

[0002] Hydrogen energy, due to its cleanliness, efficiency, safety, and sustainability, is considered one of the most promising new energy sources of the 21st century. Electrolysis of water for hydrogen production offers advantages such as a clean process and high hydrogen purity, making it a crucial technological route for achieving green hydrogen production. Currently, high-performance hydrogen evolution catalysts for water electrolysis primarily utilize precious metals such as platinum. However, the scarcity and high cost of platinum resources severely restrict the large-scale application of water electrolysis for hydrogen production. Therefore, the core challenge in current hydrogen evolution catalyst research is how to maintain or even enhance catalytic activity and stability while reducing the amount of precious metals used.

[0003] Seawater accounts for over 97% of the Earth's total water resources. Given the increasingly scarce freshwater resources, direct electrolysis of seawater to produce hydrogen is a crucial direction for large-scale green hydrogen production in the future. However, seawater contains large amounts of impurity ions such as chloride, magnesium, and calcium ions, which have a strong corrosive effect on catalyst electrode materials under acidic conditions. Existing hydrogen evolution catalysts are prone to deactivation, particle aggregation, and dissolution in acidic seawater environments, resulting in severely insufficient long-term stability.

[0004] Industrial-scale electrolytic hydrogen production places more stringent requirements on hydrogen evolution catalysts. On the one hand, industrial proton exchange membrane electrolyzers typically require operating conditions within 500 mA cm⁻¹. -2 Even at current densities of several amperes per square centimeter, most existing hydrogen evolution catalysts exhibit rapid activity decay at high current densities, failing to meet the demands of industrial applications. Furthermore, electrolyzers experience temperature increases due to the ohmic heating effect during long-term operation, with actual operating temperatures reaching over 60 °C. Existing catalysts often suffer from nanoparticle sintering and agglomeration, support corrosion, and loss of active sites at these higher temperatures, resulting in generally insufficient high-temperature stability. Therefore, developing low-noble-metal-load hydrogen evolution catalysts capable of long-term stable operation under high current densities, high temperatures, and acidic seawater environments is an urgent need to drive the industrial application of seawater electrolysis for hydrogen production.

[0005] Alloying platinum with transition metals is an effective strategy for controlling the electronic structure of platinum-based catalysts. Transition metal atoms can significantly optimize the adsorption energy of platinum for hydrogen by modulating the d-band centers of platinum, thereby enhancing intrinsic hydrogen evolution activity and reducing the amount of platinum used, effectively lowering catalyst costs. Carbon nanotubes (CNTs) possess excellent electrical conductivity, high specific surface area, and good chemical stability. After acidification, their surface is rich in oxygen-containing functional groups, providing abundant anchoring sites for metal nanoparticles, effectively inhibiting particle aggregation and shedding. Furthermore, they exhibit excellent corrosion resistance in acidic media, making them ideal catalyst support materials under harsh electrolysis conditions. However, how to organically combine these strategies to design and prepare hydrogen evolution catalysts that can achieve low platinum usage, high activity, and long-term stability under harsh conditions such as high current density, high temperature, and acidic seawater remains a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0006] To address the problems of existing seawater electrolysis hydrogen production catalysts, such as large amounts of precious metals, poor stability, and complex preparation processes, this invention provides a hydrogen evolution catalyst for acidic seawater electrolysis based on a platinum-cobalt alloy / carbon nanotube composite structure and its preparation method. This invention selects cobalt as the alloying transition metal and employs solvent-free solid-phase microwave pyrolysis technology to rapidly pyrolyze and reduce platinum acetylacetonate and cobalt acetylacetonate precursors on acidified carbon nanotubes, obtaining a composite powder with platinum-cobalt nanoparticles uniformly distributed on the carbon nanotube surface in one step. This powder is then subjected to drop-coating and electrochemical activation to finally obtain an integral composite electrode structure catalyst. The precise modulation of the platinum d-band center by cobalt atoms effectively optimizes the adsorption energy of platinum for hydrogen, significantly improving the intrinsic hydrogen evolution activity. The strong interaction (SMSI effect) between the acidified carbon nanotube support and the platinum-cobalt alloy effectively inhibits the aggregation, dissolution, and detachment of nanoparticles during long-term operation, endowing the catalyst with excellent long-term stability. The relatively low platinum loading (less than 0.1 mg cm⁻¹) further enhances the catalyst's stability. -2 This invention significantly reduces the cost of using precious metals while maintaining high catalytic activity. The synthesis method proposed in this invention is simple, highly controllable, and suitable for large-scale preparation. The prepared catalyst exhibits excellent hydrogen evolution catalytic activity and long-term stability in acidic seawater, and can achieve stable hydrogen production over a wide temperature range and at high current densities.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A hydrogen evolution catalyst for electrolytic acidic seawater based on a platinum-cobalt alloy / carbon nanotube composite structure, comprising a porous conductive substrate and a platinum-cobalt alloy / carbon nanotube composite layer supported on its surface, wherein the platinum-cobalt alloy / carbon nanotube composite layer is formed by uniformly distributing platinum-cobalt alloy nanoparticles on the surface of acidified carbon nanotubes; wherein: The platinum-cobalt alloy / carbon nanotube composite layer is constructed in situ on the surface of a porous conductive substrate by a solvent-free microwave pyrolysis and electrochemical activation process. The platinum-cobalt alloy nanoparticles are anchored on the surface of carbon nanotubes in the form of a metal solid solution, with a particle size of 3–10 nm. The atomic ratio of platinum to cobalt in the platinum-cobalt alloy nanoparticles is (8–10):1; The platinum content of platinum on carbon nanotubes in the platinum-cobalt alloy is 0.08–0.10 mg cm⁻¹. -2 ; The catalyst for hydrogen evolution through electrolysis of acidic seawater is an integral composite electrode structure with a porous conductive substrate as the current collector.

[0008] A method for preparing a hydrogen evolution catalyst for electrolytic acidic seawater based on a platinum-cobalt alloy / carbon nanotube composite structure includes the following steps: The first step is the acidification treatment of carbon nanotubes: carbon nanotubes are added to a mixed solution of concentrated sulfuric acid and concentrated nitric acid and refluxed. After filtration, the solution is repeatedly washed with deionized water until the filtrate is neutral. After drying, acidified carbon nanotubes are obtained. Furthermore, the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed solution is 3:1; Furthermore, the solid-liquid ratio of the carbon nanotubes to the mixed acid solution is 1 g : (20–50) mL; Furthermore, the reflux temperature is 60–95 °C, and the reflux time is 1.5–3 hours.

[0009] The second step is to grind and mix the precursors: weigh platinum acetylacetonate, cobalt acetylacetonate, and the acidified carbon nanotubes obtained in the first step according to the mass ratio (1.8–2.5):0.65:1, and grind them thoroughly in a mortar until they are mixed evenly to obtain a mixture.

[0010] The third step is solvent-free microwave synthesis: the mixture obtained in the second step is transferred to a quartz bottle filled with argon gas and microwaved at 600–800 W for 30–120 seconds to pyrolyze and reduce the precursor to generate platinum-cobalt alloy nanoparticles loaded on carbon nanotubes; after the reaction, the product is centrifuged and washed, and then placed in a vacuum drying oven to dry, obtaining platinum-cobalt alloy / carbon nanotube composite powder.

[0011] Step 4, Electrode preparation: The platinum-cobalt alloy / carbon nanotube composite powder obtained in step 3 is mixed with isopropanol and Nafion solution (mass concentration 5.0 wt.%), and ultrasonically dispersed to form a uniform suspension. Then, the suspension is drop-coated onto the cleaned porous conductive substrate in multiple batches and vacuum dried at room temperature to obtain the platinum-cobalt alloy / carbon nanotube / porous conductive substrate precursor electrode. Furthermore, the concentration of the platinum-cobalt alloy / carbon nanotube composite powder in each milliliter of suspension is 1.0–2.0 mg / mL. -1 ; Furthermore, the loading amount of the platinum-cobalt alloy / carbon nanotube composite powder on the porous conductive substrate is 1.0 mg cm⁻¹. -2 , ; Furthermore, the porous conductive substrate is one of copper foam, carbon cloth, or carbon paper, and is ultrasonically cleaned with acetone and ethanol in sequence to remove surface contaminants before use.

[0012] Step 5, electrochemical activation: Using the platinum-cobalt alloy / carbon nanotube / porous conductive substrate precursor electrode obtained in step 4 as the working electrode, a graphite rod as the counter electrode, and an Hg / Hg2SO4 electrode as the reference electrode, electrochemical activation was carried out in a sodium sulfate solution with pH adjusted to weak acidity by dilute sulfuric acid at a constant current density until the chronopotential curve tended to stabilize. After that, it was washed with deionized water to obtain the platinum-cobalt alloy / carbon nanotube composite catalyst.

[0013] Furthermore, the sodium sulfate solution has a concentration of 0.3 M and a pH of 2–3; Furthermore, the electrochemical activation time is 2–12 hours, and the constant current density is 100–200 mA cm⁻¹. -2 .

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1) This invention uses a solvent-free solid-phase microwave pyrolysis method to prepare platinum-cobalt alloy / carbon nanotube composite powder. The synthesis time is only in the minute range, no organic solvent is required, the process is simple and environmentally friendly, the preparation cycle is greatly shortened, and it is easy to scale up production. 2) This invention optimizes the adsorption energy of platinum for hydrogen by precisely modulating the center of the platinum d-band with cobalt atoms, significantly improving the intrinsic hydrogen evolution activity, while using a low amount of precious metal (platinum element loading is only about 0.1 mg cm⁻¹). -2 This effectively reduced catalyst costs; 3) This invention utilizes the strong interaction (SMSI effect) between acidified carbon nanotubes and platinum-cobalt alloy to effectively suppress the aggregation, dissolution and shedding of platinum-cobalt nanoparticles during long-term high-temperature operation. It exhibits excellent hydrogen evolution activity and long-term stability in acidic seawater and other acidic electrolyte media, and is suitable for continuous operation at high current density. 4) The catalyst obtained by this invention has good corrosion resistance to complex impurity ions in acidic seawater and can work stably in a wide temperature range and at high current density. It is not only suitable for large-scale acidic seawater electrolysis hydrogen production industrial scenarios, but also has broad application prospects in other catalytic hydrogen evolution fields such as the chlor-alkali industry.

[0015] In summary, the catalyst of this invention has a low noble metal loading, a simple and environmentally friendly preparation process, and exhibits excellent hydrogen evolution activity and long-term stability under high temperature and high current density electrolysis conditions in acidic seawater. It effectively overcomes the problems of easy deactivation and insufficient stability of traditional platinum-based catalysts in acidic media, and provides a new technical solution for efficient and stable hydrogen production by seawater electrolysis under high current density and wide temperature range. Attached Figure Description

[0016] Figure 1 This is a transmission electron microscope image of the catalyst based on the platinum-cobalt alloy / carbon nanotube composite structure prepared in Example 1 of this invention; Figure 2 This is a high-angle annular dark-field scanning transmission electron microscope image of the platinum-cobalt alloy / carbon nanotube composite catalyst prepared in Example 1 of this invention; Figure 3 This is a high-magnification transmission electron microscope image of the catalyst based on the platinum-cobalt alloy / carbon nanotube composite structure prepared in Example 1 of the present invention. The circled part represents the platinum-cobalt nanoclusters, whose lattice fringe spacing conforms to the Pt (111) crystal plane. Figure 4 This invention describes the catalytic activity characterization of the platinum-cobalt alloy / carbon nanotube composite catalyst prepared in Example 1 of this invention for the electrolysis of acidic seawater for hydrogen evolution, and compares its activity with that of a commercial Pt / C catalyst. Test method: A three-electrode system was used, with natural seawater and 0.5 M sulfuric acid as the electrolyte. The working electrode was the catalyst prepared in this invention, the Hg / Hg₂SO₄ (K₂SO₄ saturated) electrode was used as the reference electrode, and the iridium-tantalum-titanium sheet electrode was used as the counter electrode. The scan rate was 5 mV / s. -1 The electrochemical workstation is a CHI760E.

[0017] Figure 5 The catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure prepared in Example 1 of this invention is used at high current densities (0.5–5.0 A cm⁻¹). -2 Catalytic activity characterization of hydrogen evolution by electrolysis of acidic seawater. Test method: A three-electrode system was used, with natural seawater and 0.5 M sulfuric acid as the electrolyte. The working electrode was the catalyst prepared in this invention, the Hg / Hg₂SO₄ (K₂SO₄ saturated) electrode was used as the reference electrode, and the iridium-tantalum-titanium sheet electrode was used as the counter electrode. A MESTEK-DP3060 DC power supply was used with current densities of 0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 A cm⁻¹. -2 Run for 30 minutes and record the corresponding voltage.

[0018] Figure 6This invention relates to the stability characterization of the hydrogen production from acidic seawater prepared in Example 1 of this invention based on a platinum-cobalt alloy / carbon nanotube composite catalyst. Test method: A three-electrode system was used, with natural seawater and 0.5 M sulfuric acid as the electrolyte. The working electrode was the catalyst prepared in this invention, the Hg / Hg₂SO₄ (K₂SO₄ saturated) electrode was used as the reference electrode, and the iridium-tantalum-titanium sheet electrode was used as the counter electrode. The stability was recorded at 500 mA cm⁻¹. -2 and 1 A cm -2 Chronopotential curves at current density, electrochemical workstation: CHI760E. Detailed Implementation

[0019] In view of the many shortcomings of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles. However, it should be understood that within the scope of this invention, the above-mentioned technical features of this invention and the technical features specifically described below (in embodiments) can be combined with each other to constitute new or preferred technical solutions.

[0020] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0021] Comparative Example 1 Preparation of commercial platinum-carbon / foamed copper catalysts and their hydrogen evolution performance in acidic seawater electrolysis Take 2 mg of commercial 20% platinum-carbon catalyst powder, add 1.9 mL of isopropanol and 0.1 mL of Nafion solution (5.0 wt.%), and ultrasonically disperse for at least 1 hour until a homogeneous suspension is formed. Pipettes with dimensions of 1 × 2 cm... 2 The copper foam was ultrasonically cleaned sequentially with acetone and ethanol for 15 minutes each to remove surface contaminants. The resulting suspension was then drop-coated onto the cleaned copper foam substrate and vacuum-dried at room temperature for 12 hours, yielding a loading of approximately 1.0 mg cm⁻¹. -2 Platinum-carbon / foamed copper catalyst.

[0022] Depend on Figure 4 and Figure 6 As can be seen, the electrochemical performance of the above-prepared platinum-carbon / foamed copper catalyst was tested in acidic seawater containing 0.5 M sulfuric acid, achieving 500 mA cm⁻¹ at 257 mV. -2 Current density; at 25 °C and 500 mA cm⁻¹ -2 Under constant current density, a significant potential decay with an increase of nearly 300 mV was observed over approximately 230 hours.

[0023] Example 1 Preparation of platinum-cobalt alloy / carbon nanotube / copper foam catalyst and its hydrogen evolution performance in acidic seawater electrolysis 1) Add 3 g of carbon nanotubes to 110 mL of a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, and reflux at 90 °C for 2.5 hours. After the reaction is complete, filter the solution and wash it repeatedly with deionized water until the filtrate is neutral. After drying, acidified carbon nanotubes are obtained.

[0024] 2) Weigh 10 mg of platinum acetylacetonate, 3.25 mg of cobalt acetylacetonate and 5 mg of the above-mentioned acidified carbon nanotubes (mass ratio 2.0:0.65:1), place them in a mortar and grind for 15 min until they are mixed evenly to obtain a homogeneous mixed powder.

[0025] 3) The above mixed powder was transferred to a 10 mL quartz bottle filled with argon gas and placed in a microwave reactor. It was treated at 700 W for 60 seconds to rapidly pyrolyze and reduce the platinum acetylacetonate and cobalt acetylacetonate precursors, generating platinum-cobalt alloy nanoparticles loaded on carbon nanotubes. The resulting product was washed three times with anhydrous ethanol by centrifugation to remove residual organic matter, and then dried in a vacuum drying oven at 60 °C for 12 hours to obtain platinum-cobalt alloy / carbon nanotube composite powder.

[0026] 4) Take 2 mg of the above platinum-cobalt alloy / carbon nanotube composite powder, add 1.9 mL of isopropanol and 0.1 mL of Nafion solution (5.0 wt.%), and ultrasonically disperse for at least 1 hour until a uniform suspension is formed. Then, prepare a 1 × 2 cm... 2 The copper foam was ultrasonically cleaned sequentially with acetone and ethanol for 15 minutes each to remove surface contaminants. The resulting suspension was then evenly drop-coated onto the cleaned copper foam substrate in multiple portions and vacuum-dried at room temperature for 12 hours, yielding a loading of approximately 1.0 mg / cm³. -2 Platinum-cobalt alloy / carbon nanotube / copper foam precursor electrode.

[0027] 5) Using the aforementioned platinum-cobalt alloy / carbon nanotube / copper foam precursor electrode as the working electrode, a graphite rod as the counter electrode, and an Hg / Hg₂SO₄ (K₂SO₄ saturated) electrode as the reference electrode, an application of 125 mA cm⁻¹ was performed in a 0.3 M sodium sulfate aqueous solution at pH 2.5 (adjusted with dilute sulfuric acid). -2 Electrochemical activation was performed using a constant current density until the chronopotential curve stabilized. After thorough washing with deionized water, the platinum-cobalt alloy / carbon nanotube composite catalyst was finally obtained.

[0028] Depend on Figure 4 As shown in Figures 5 and 6, the electrochemical performance of the platinum-cobalt alloy / carbon nanotube composite catalyst prepared above was tested in acidic seawater containing 0.5 M sulfuric acid, and the current density was 500 mA cm⁻¹ at 25 °C. -2Its overpotential was 230 mV, and there was no significant change in potential after more than 2000 hours of continuous operation; the current density at 60 °C was 500 mA cm⁻¹. -2 Its overpotential further decreased to 118 mV, and remained basically stable after more than 3000 hours of continuous operation; the current density at 25 °C was 0.5–5.0 A cm⁻¹. -2 The overpotential ranges from 0.23 to 0.63 V. Therefore, the catalyst obtained in this invention exhibits superior catalytic activity for hydrogen production via water electrolysis in acidic seawater compared to commercially available noble metal Pt / C catalysts, while also demonstrating excellent high-current-density hydrogen evolution performance and stability.

[0029] Example 2 Preparation of platinum-cobalt alloy / carbon nanotube / carbon cloth catalysts and their hydrogen evolution performance in acidic seawater electrolysis 1) Add 3 g of carbon nanotubes to 60 mL of a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, and reflux at 95 °C for 1.5 hours. After the reaction is complete, filter the solution and wash it repeatedly with deionized water until the filtrate is neutral. After drying, acidified carbon nanotubes are obtained.

[0030] 2) Weigh 10 mg of platinum acetylacetonate, 3.5 mg of cobalt acetylacetonate and 5.5 mg of the above-mentioned acidified carbon nanotubes (mass ratio 1.8:0.65:1), place them in a mortar and grind for 15 min until they are mixed evenly to obtain a homogeneous mixed powder.

[0031] 3) The above mixed powder was transferred to a 10 mL quartz bottle filled with argon gas and placed in a microwave reactor. It was then treated at 800 W for 30 seconds to rapidly pyrolyze and reduce the platinum acetylacetonate and cobalt acetylacetonate precursors, generating platinum-cobalt alloy nanoparticles loaded on carbon nanotubes. The resulting product was washed three times with anhydrous ethanol by centrifugation to remove residual organic matter, and then dried in a vacuum drying oven at 60 °C for 12 hours to obtain platinum-cobalt alloy / carbon nanotube composite powder.

[0032] 4) Take 2 mg of the above platinum-cobalt alloy / carbon nanotube composite powder, add 950 μL of isopropanol and 50 μL of Nafion solution (5.0 wt.%), and ultrasonically disperse for at least 1 hour until a uniform suspension is formed. (The following text appears to be unrelated and possibly a separate instruction: "Show a 1 × 2 cm...") 2 The carbon cloth was ultrasonically cleaned sequentially with acetone and ethanol for 15 minutes each to remove surface contaminants. The resulting suspension was then evenly drop-coated onto the cleaned carbon cloth substrate in multiple applications and vacuum-dried at room temperature for 12 hours, yielding a loading of approximately 1.0 mg cm⁻¹. -2 Platinum-cobalt alloy / carbon nanotube / carbon cloth precursor electrode.

[0033] 5) Using the aforementioned platinum-cobalt alloy / carbon nanotube / carbon cloth precursor electrode as the working electrode, a graphite rod as the counter electrode, and an Hg / Hg₂SO₄ (K₂SO₄ saturated) electrode as the reference electrode, an application of 100 mA cm⁻¹ was performed in a 0.3 M sodium sulfate aqueous solution with a pH of 2 (adjusted with dilute sulfuric acid). -2 Electrochemical activation was performed using a constant current density until the chronopotential curve stabilized. After thorough washing with deionized water, the platinum-cobalt alloy / carbon nanotube composite catalyst was finally obtained.

[0034] The electrochemical performance of the prepared platinum-cobalt alloy / carbon nanotube composite catalyst was tested in acidic seawater containing 0.5 M sulfuric acid, with a current density of 500 mA cm⁻¹ at 25 °C. -2 Its overpotential was 233 mV, and there was no significant change in potential after more than 1500 hours of continuous operation; the current density at 60 °C was 500 mA cm⁻¹. -2 Its overpotential further decreased to 125mV, and remained basically stable after more than 1000 hours of continuous operation; the current density at 25 ℃ was 0.5–5.0 A cm⁻¹. -2 The overpotential ranges from 0.23 to 0.65 V. Therefore, the catalyst obtained in this invention exhibits superior catalytic activity for hydrogen production through water electrolysis in acidic seawater compared to commercially available noble metal Pt / C catalysts, while also demonstrating excellent high-current-density hydrogen evolution performance and stability.

[0035] Example 3 Preparation of platinum-cobalt alloy / carbon nanotube / carbon paper catalysts and their hydrogen evolution performance in acidic seawater electrolysis 1) Add 3 g of carbon nanotubes to 150 mL of a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, and reflux at 60 °C for 3 hours. After the reaction is complete, filter the solution and wash it repeatedly with deionized water until the filtrate is neutral. After drying, acidified carbon nanotubes are obtained.

[0036] 2) Weigh 10 mg of platinum acetylacetonate, 2.6 mg of cobalt acetylacetonate and 4 mg of the above-mentioned acidified carbon nanotubes (mass ratio 2.5:0.65:1), place them in a mortar and grind for 15 min until they are mixed evenly to obtain a homogeneous mixed powder.

[0037] 3) The above mixed powder was transferred to a 10 mL quartz bottle filled with argon gas and placed in a microwave reactor. It was then treated at 600 W for 120 seconds to rapidly pyrolyze and reduce the platinum acetylacetonate and cobalt acetylacetonate precursors, generating platinum-cobalt alloy nanoparticles loaded on carbon nanotubes. The resulting product was washed three times with anhydrous ethanol by centrifugation to remove residual organic matter, and then dried in a vacuum drying oven at 60 °C for 12 hours to obtain platinum-cobalt alloy / carbon nanotube composite powder.

[0038] 4) Take 3 mg of the above platinum-cobalt alloy / carbon nanotube composite powder, add 1.9 mL of isopropanol and 0.1 mL of Nafion solution (5.0 wt.%), and ultrasonically disperse for at least 1 hour until a uniform suspension is formed. Then, prepare a 1 × 2 cm... 2 The carbon paper was ultrasonically cleaned sequentially with acetone and ethanol for 15 minutes each to remove surface contaminants. The resulting suspension was then evenly drop-coated onto the cleaned carbon paper substrate in multiple portions and vacuum-dried at room temperature for 12 hours, yielding a loading of approximately 1.0 mg cm⁻¹. -2 Platinum-cobalt alloy / carbon nanotube / carbon paper precursor electrode.

[0039] 5) Using the aforementioned platinum-cobalt alloy / carbon nanotube / carbon paper precursor electrode as the working electrode, a graphite rod as the counter electrode, and an Hg / Hg₂SO₄ (K₂SO₄ saturated) electrode as the reference electrode, an application of 200 mA cm⁻¹ was performed in a 0.3 M sodium sulfate aqueous solution with a pH of 3 (adjusted with dilute sulfuric acid). -2 Electrochemical activation was performed using a constant current density until the chronopotential curve stabilized. After thorough washing with deionized water, the platinum-cobalt alloy / carbon nanotube composite catalyst was finally obtained.

[0040] The electrochemical performance of the prepared platinum-cobalt alloy / carbon nanotube composite catalyst was tested in acidic seawater containing 0.5 M sulfuric acid, with a current density of 500 mA cm⁻¹ at 25 °C. -2 Its overpotential was 235 mV, and there was no significant change in potential after more than 1000 hours of continuous operation; the current density at 60 °C was 500 mA cm⁻¹. -2 Its overpotential further decreased to 130mV, and remained basically stable after more than 1500 hours of continuous operation; the current density at 25 ℃ was 0.5–5.0 A cm⁻¹. -2 The overpotential ranges from 0.23 to 0.67 V. Therefore, the catalyst obtained in this invention exhibits superior catalytic activity for hydrogen production from water electrolysis in acidic seawater compared to commercially available noble metal Pt / C catalysts, while also demonstrating excellent high-current-density hydrogen evolution performance and stability.

[0041] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A catalyst for hydrogen evolution in acidic seawater based on a platinum-cobalt alloy / carbon nanotube composite structure, characterized in that, The electrolytic acidic seawater hydrogen evolution catalyst is an integral composite electrode structure with a porous conductive substrate as the current collector. It comprises a porous conductive substrate and a platinum-cobalt alloy / carbon nanotube composite layer supported on its surface. The platinum-cobalt alloy / carbon nanotube composite layer is formed by uniformly distributing platinum-cobalt alloy nanoparticles on the surface of acidified carbon nanotubes. The platinum-cobalt alloy / carbon nanotube composite layer is constructed in situ on the surface of a porous conductive substrate by a solvent-free microwave pyrolysis and electrochemical activation process. The platinum-cobalt alloy nanoparticles are anchored on the surface of carbon nanotubes in the form of a metal solid solution.

2. The electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 1, characterized in that, The atomic ratio of platinum to cobalt in the platinum-cobalt alloy nanoparticles is (8–10):

1.

3. The electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 1, characterized in that, The mass loading of platinum element in the platinum cobalt alloy on the carbon nanotubes is 0.08-0.10 mg cm -2 .

4. The electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 1, characterized in that, The platinum-cobalt alloy nanoparticles have a particle size of 3–10 nm.

5. A method for preparing an electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure as described in any one of claims 1-4, characterized in that, Includes the following steps: The first step is the acidification treatment of carbon nanotubes: carbon nanotubes are added to a mixed solution of concentrated sulfuric acid and concentrated nitric acid and refluxed. After filtration, the solution is repeatedly washed with deionized water until the filtrate is neutral. After drying, acidified carbon nanotubes are obtained. The second step is to grind and mix the precursors: weigh platinum acetylacetonate, cobalt acetylacetonate, and the acidified carbon nanotubes obtained in the first step according to the mass ratio (1.8–2.5):0.65:1, grind them thoroughly in a mortar until they are mixed evenly to obtain a mixture; The third step is solvent-free microwave synthesis: the mixture obtained in the second step is transferred to a quartz bottle filled with argon gas and microwaved to pyrolyze and reduce the precursor to generate platinum-cobalt alloy nanoparticles loaded on carbon nanotubes; after the reaction, the product is centrifuged and washed, and then placed in a vacuum drying oven to dry to obtain platinum-cobalt alloy / carbon nanotube composite powder. Step 4, Electrode preparation: The platinum-cobalt alloy / carbon nanotube composite powder obtained in step 3 is mixed with isopropanol and Nafion solution, and ultrasonically dispersed to form a uniform suspension. Then, the suspension is drop-coated onto the cleaned porous conductive substrate in multiple batches and vacuum dried at room temperature to obtain the platinum-cobalt alloy / carbon nanotube / porous conductive substrate precursor electrode. Step 5, electrochemical activation: Using the platinum-cobalt alloy / carbon nanotube / porous conductive substrate precursor electrode obtained in step 4 as the working electrode, electrochemical activation is performed to obtain a platinum-cobalt alloy / carbon nanotube composite catalyst.

6. The preparation method of the electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 5, characterized in that, In the first step: The volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed solution is 3:1; The solid-liquid ratio of the carbon nanotubes to the mixed acid solution is 1 g : (20–50) mL; The reflux temperature is 60–95 °C, and the reflux time is 1.5–3 hours.

7. The preparation method of the electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 5, characterized in that, In the third step, the microwave processing power is 600–800 W, and the time is 30–120 seconds.

8. The preparation method of the electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 5, characterized in that, In the fourth step: The concentration of platinum-cobalt alloy / carbon nanotube composite powder in the suspension was 1.0-2.0 mg / mL per milliliter of suspension -1 ; The loading amount of the platinum-cobalt alloy / carbon nanotube composite powder on the porous conductive substrate is 1.0 mg cm⁻¹. -2 , ; The porous conductive substrate is one of copper foam, carbon cloth or carbon paper. The Nafion solution had a mass concentration of 5.0 wt.%.

9. The preparation method of the electrolytic acidic seawater hydrogen evolution catalyst based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 5, characterized in that, The fifth step of the electrochemical activation process is as follows: using a graphite rod as the counter electrode and an Hg / Hg2SO4 electrode as the reference electrode, electrochemical activation is carried out in a sodium sulfate solution at a constant current density until the chronopotential curve tends to stabilize. Then, it is washed with deionized water to obtain a platinum-cobalt alloy / carbon nanotube composite catalyst.

10. The preparation method of a hydrogen evolution catalyst for electrolytic acidic seawater based on a platinum-cobalt alloy / carbon nanotube composite structure according to claim 9, characterized in that, The sodium sulfate solution has a concentration of 0.3 M and a pH of 2–3; the electrochemical activation time is 2–12 hours, and the constant current density is 100–200 mA cm⁻¹. -2 .

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