Bimetallic catalyst for hydrogen production by water electrolysis and preparation method thereof

Abstract

The application discloses a bimetallic catalyst for water electrolysis hydrogen production and a preparation method thereof, and relates to the technical field of water electrolysis hydrogen production. The application provides a bimetallic catalyst for water electrolysis hydrogen production and a preparation method thereof. Nanocrystalline iridium and palladium are loaded on a high specific surface area carbon carrier through a liquid phase reduction method, and the dispersity and particle size of the bimetallic particles are controlled through carbon loading. The synergistic effect between the palladium and iridium metals is used to improve the electron transfer between the metals, thereby improving the catalyst activity. Then, the catalyst is subjected to high-temperature heat treatment through a stepwise heating method, so that the coexistence of amorphous and crystalline structures of iridium oxide is realized, and the water electrolysis capacity of the catalyst is improved.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis hydrogen production technology, specifically to a bimetallic catalyst for water electrolysis hydrogen production and its preparation method. Background Technology

[0002] The current global climate change and energy crisis urgently require the development of economical, efficient, and eco-friendly energy storage and conversion systems. Among these, water electrolysis for hydrogen production and hydrogen fuel cell technology are of great significance for the utilization of hydrogen energy, which is recognized worldwide as a clean energy carrier.

[0003] In water electrolysis for hydrogen production, compared to alkaline water electrolysis, proton exchange membrane (PEM) water electrolysis offers advantages such as higher current density, higher hydrogen purity, and faster response speed. PEM water electrolysis technology also boasts higher efficiency. During water electrolysis, iridium is considered the optimal catalyst for the oxygen evolution reaction (OER) due to its excellent activity and stability in acidic media. However, its low reserves and high price severely hinder its large-scale application. Therefore, it is necessary to enhance the intrinsic activity of the active sites in practical applications to reduce the use of precious metals.

[0004] The rational introduction of other metals into noble metal systems often enhances catalytic activity. This is because changes in electronic or geometric structures lead to the adsorption and transfer of bond energy to reaction intermediates on the catalyst surface, or the synergistic effect of generating multiple active sites. Structures such as IrCo, IrCu, and IrRu alloys exhibit higher OER performance than traditional IrO2. This is because the leaching of dopants may expose more high-index crystal planes, thus improving OER performance. The fundamental reason is due to the interfacial IrO... x The structure achieves high OER performance.

[0005] Patent application JP2015534607A discloses an electrolytic electrocatalyst and an electrolysis process, such as the electrolysis of water, more specifically, the generation of hydrogen at the cathode or oxygen at the anode of a water electrolyzer. This is used and applied in water electrolyzers containing such an electrode catalyst. The electrode catalyst used in this invention comprises a combination of palladium and iridium. After preparing the PdIr alloy catalyst by chemical reduction, the invention removes hydroxides and oxides from the catalyst surface by heat treatment at 150°C in a hydrogen atmosphere. The relatively low treatment temperature does not lead to catalyst sintering or loss of specific surface area; however, due to the low heat treatment temperature and the fact that the heat treatment is carried out under oxygen-free conditions, the PdIr catalyst mainly exists in elemental form, especially the main active metal Ir, rather than IrO. x The presence of this physical form leads to a decline in catalyst activity during long-term operation.

[0006] Pyrolysis and liquid-phase colloid methods are commonly used to prepare Ir nanocrystals. Pyrolysis requires the addition of surfactants to disperse the nanocrystals, which can lead to residual organic matter on the surface of the nanoparticles after pyrolysis, thus affecting catalyst activity. Liquid-phase colloid methods, on the other hand, obtain nanocrystals through chemical reactions between precursors and other additives in solution. The experimental operation is simple, and the structure, morphology, and size of the nanocrystals can be easily controlled. However, due to the large use of alcohol-based organic solvents, the generated nanocrystals exhibit high stability in the solvent, resulting in severe agglomeration of large-sized crystals, making product collection difficult and leading to low yield. Furthermore, high-temperature calcination of the nanocrystals in the liquid-phase colloid method can easily cause further sintering of the catalyst, reducing its activity. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a bimetallic catalyst for hydrogen production via water electrolysis and its preparation method. This invention employs a liquid-phase reduction method to prepare a carbon-supported palladium-iridium bimetallic catalyst. High specific surface area carbon black enhances the high dispersion of palladium and iridium on the support, resulting in small-particle-size, highly active metals. Subsequently, a stepped-heat calcination process removes oxygen-containing groups from the catalyst surface and oxidizes elemental iridium into more durable iridium oxide. The high specific surface area of ​​the carbon black prevents iridium from agglomerating during calcination. Compared to iridium, metallic palladium has a larger particle size, providing more contact surface with the carbon black. Most of the iridium metal adheres to the palladium metal and exists on the support surface through palladium-carbon interactions, making it less prone to sintering and agglomeration during high-temperature calcination.

[0008] The specific technical solution of the present invention is as follows:

[0009] A method for preparing a bimetallic catalyst for hydrogen production by water electrolysis includes the following steps:

[0010] (1) Dissolve the iridium precursor in solvent 1 to obtain an iridium precursor solution, dissolve the palladium precursor in solvent 2 to obtain a palladium precursor solution, and mix and disperse the obtained iridium precursor solution and palladium precursor solution evenly to obtain mixed solution A;

[0011] (2) Disperse carbon black, organic alcohol, alkali solution and reducing agent evenly to obtain mixed solution B;

[0012] (3) Add the mixed solution B obtained in step (2) to the mixed solution A obtained in step (1) to carry out the reduction reaction. After the reaction is completed, the reaction solution is obtained.

[0013] (4) Add acid to the reaction solution in step (3) to obtain the reaction solid;

[0014] (5) The reaction solids in step (4) are subjected to step heating and calcination to obtain the bimetallic catalyst for hydrogen production by water electrolysis.

[0015] Specifically, in step (1), the iridium precursor is chloroiridium acid, iridium acetylacetonate, or iridium acetate.

[0016] Solvent 1 is water.

[0017] The iridium precursor solution has a mass fraction of 5%-20%.

[0018] The palladium precursor is palladium acetate.

[0019] Solvent 2 is acetone.

[0020] The palladium precursor solution has a mass fraction of 5%-20%.

[0021] The iridium and palladium precursor solutions were dispersed using a sand mill for 30-60 minutes, with cooling water flowing through during the dispersion process.

[0022] Preferably, in step (1), the mass ratio of palladium metal to iridium metal in mixed solution A is 1:1-5. The mass ratios of iridium metal and palladium metal in step (1) to the carbon black, alkaline solution, and reducing agent in step (2) are 1:1-10, 1:50-200, and 1:1-10, respectively. The synergistic effect between palladium and iridium metals enhances electron transfer between the metals, thereby improving catalyst activity.

[0023] In step (2), the carbon black is acetylene black, specifically BP2000, EC300J, or Cabot FCX800.

[0024] The organic alcohol is at least one selected from ethanol, isopropanol, and ethylene glycol.

[0025] The mass ratio of the carbon black to the organic alcohol is 1:100-400.

[0026] The alkaline solution is at least one selected from sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, and sodium hydroxide aqueous solution, and the mass fraction of the alkaline solution is 10%-25%.

[0027] The reducing agent is at least one of methanol, formaldehyde, and formic acid.

[0028] In step (3), the dropping rate is 5-20 ml / min, the temperature of the reduction reaction is 70-90℃, and the reaction time is 3-9 h. Iridium and palladium are loaded onto a high specific surface area carbon support by liquid-phase reduction.

[0029] In step (4), the acid solution is at least one of sulfuric acid, nitric acid, and phosphoric acid.

[0030] In step (1), the mass ratio of iridium metal and palladium metal to the acid solution in step (4) is 1:10-20.

[0031] In step (5), the stepped heating and calcination is divided into three stages:

[0032] Stage 1: Heat to 100-200℃ at a rate of 5-10℃, and heat treat for 30-90 minutes.

[0033] Phase 2: At the temperature of Phase 1, increase the temperature to 250-350℃ at a rate of 5-10℃, and heat-treat for 60-120 minutes.

[0034] Phase 3: Heat the temperature from the temperature in Phase 2 to 400-600℃ at a heating rate of 5-10℃, heat treat for 90-180 minutes, and then cool.

[0035] The stepped heating calcination method can achieve the coexistence of iridium oxide amorphous and crystalline structures.

[0036] The present invention also provides a bimetallic catalyst for hydrogen production by water electrolysis prepared by the above preparation method.

[0037] The beneficial effects of this invention are:

[0038] This invention provides a bimetallic catalyst for hydrogen production by water electrolysis and its preparation method. Nanocrystalline iridium and palladium are loaded onto a high specific surface area carbon support via liquid-phase reduction. The carbon loading controls the dispersion and particle size of the bimetallic particles. The synergistic effect between palladium and iridium enhances electron transfer between the metals, thereby improving catalyst activity. Then, the catalyst is subjected to high-temperature heat treatment using a stepped heating method, achieving the coexistence of amorphous and crystalline iridium oxide structures, thus improving the catalyst's water electrolysis capability. Attached Figure Description

[0039] Figure 1 The OER performance test graphs are for Examples 1-6 and Comparative Example 1.

[0040] Figure 2 The chronoamperometry results are for Example 4 and Comparative Example 1.

[0041] Figure 3 This is the SEM characterization map of Example 4.

[0042] Figure 4 This is the SEM characterization map of Example 4.

[0043] Figure 5 The image shown is a SEM characterization map of Comparative Example 1.

[0044] Figure 6The image shown is a SEM characterization map of Comparative Example 1. Detailed Implementation

[0045] Example 1

[0046] 1. Dissolve iridium acetate in deionized water to prepare a 10wt% iridium acetate aqueous solution; dissolve palladium acetate in acetone to prepare a 10wt% palladium acetate acetone solution; weigh 2.57g of iridium acetate aqueous solution and 1.26g of palladium acetate acetone solution, with an iridium to palladium metal mass ratio of 0.7:0.3, and disperse in a sand mill for 30 minutes.

[0047] 2. Dissolve sodium carbonate in an aqueous solution to prepare a 20% sodium carbonate aqueous solution; weigh 0.8g of EC300J carbon black and 160g of ethanol into a beaker, add 20g of the 20% sodium carbonate aqueous solution and 1g of formic acid as a reducing agent; then place the mixed solution in a sand mill and disperse it for 120 minutes.

[0048] 3. Transfer the well dispersed carbon black mixture to a three-necked flask, place it in a water bath, set the reaction temperature of the water bath to 80℃, and stir magnetically; set the flow rate of the peristaltic pump to 5ml / min, and add the palladium and iridium precursor mixture dropwise to the three-necked flask during the reaction; after all the transfer is completed, continue the reaction for 6 hours.

[0049] 4. Allow the reacted solution to cool naturally, then transfer it to a large beaker, add 2g of pure sulfuric acid (98% by mass), then add a large amount of deionized water, stir and allow the mixture to settle naturally.

[0050] 5. After the catalyst has settled, filter it by pressure and then place it in a vacuum drying oven and dry it under vacuum at 70°C for 16 hours.

[0051] 6. Place the dried catalyst in a calcination furnace and then perform heat treatment. In stage 1, heat to 150°C at a heating rate of 5°C / min, and then heat treat at this temperature for 60 minutes. Then, continue heating to 300°C at a heating rate of 5°C / min and heat treat for 90 minutes. Finally, continue heating to 450°C at a heating rate of 5°C / min and heat treat for 120 minutes. After natural cooling, the desired catalyst is obtained and labeled as Pd. 0.3 -Ir 0..7 / C-450.

[0052] Example 2

[0053] 1. Dissolve iridium acetate in deionized water to prepare a 10wt% iridium acetate aqueous solution; dissolve palladium acetate in acetone to prepare a 10wt% palladium acetate acetone solution; weigh 1.84g of iridium acetate aqueous solution and 2.1g of palladium acetate acetone solution, with an iridium to palladium metal mass ratio of 1:1, and disperse in a sand mill for 30 minutes.

[0054] 2. Dissolve sodium carbonate in an aqueous solution to prepare a 20% sodium carbonate aqueous solution; weigh 0.8g of EC300J carbon black and 160g of ethanol into a beaker, add 20g of the 20% sodium carbonate aqueous solution and 1g of formic acid as a reducing agent; then place the mixed solution in a sand mill and disperse it for 120 minutes.

[0055] 3. Transfer the well dispersed carbon black mixture to a three-necked flask, place it in a water bath, set the reaction temperature of the water bath to 80℃, and stir magnetically; set the flow rate of the peristaltic pump to 5ml / min, and add the palladium and iridium precursor mixture dropwise to the three-necked flask during the reaction; after all the transfer is completed, continue the reaction for 6 hours.

[0056] 4. Allow the reacted solution to cool naturally, then transfer it to a large beaker, add 2g of pure sulfuric acid (98% by mass), then add a large amount of deionized water, stir and allow the mixture to settle naturally.

[0057] 5. After the catalyst has settled, filter it by pressure and then place it in a vacuum drying oven and dry it under vacuum at 70°C for 16 hours.

[0058] 6. Place the dried catalyst in a calcination furnace and then perform heat treatment. In stage 1, heat to 150°C at a heating rate of 5°C / min, and then heat treat at this temperature for 60 minutes. Then, continue heating to 300°C at a heating rate of 5°C / min and heat treat for 90 minutes. Finally, continue heating to 450°C at a heating rate of 5°C / min and heat treat for 120 minutes. After natural cooling, the desired catalyst is obtained and labeled as Pd. 0.5 -Ir 0.5 / C-450.

[0059] Example 3

[0060] 1. Dissolve iridium acetate in deionized water to prepare a 10wt% iridium acetate aqueous solution; dissolve palladium acetate in acetone to prepare a 10wt% palladium acetate acetone solution; weigh 1.1g of iridium acetate aqueous solution and 2.94g of palladium acetate acetone solution, with an iridium to palladium metal mass ratio of 0.3:0.7, and disperse in a sand mill for 30 minutes.

[0061] 2. Dissolve sodium carbonate in an aqueous solution to prepare a 20% sodium carbonate aqueous solution; weigh 0.8g of EC300J carbon black and 160g of ethanol into a beaker, add 20g of the 20% sodium carbonate aqueous solution and 1g of formic acid as a reducing agent; then place the mixed solution in a sand mill and disperse it for 120 minutes.

[0062] 3. Transfer the well dispersed carbon black mixture to a three-necked flask, place it in a water bath, set the reaction temperature of the water bath to 80℃, and stir magnetically; set the flow rate of the peristaltic pump to 5ml / min, and add the palladium and iridium precursor mixture dropwise to the three-necked flask during the reaction; after all the transfer is completed, continue the reaction for 6 hours.

[0063] 4. Allow the reacted solution to cool naturally, then transfer it to a large beaker, add 2g of pure sulfuric acid (98% by mass), then add a large amount of deionized water, stir and allow the mixture to settle naturally.

[0064] 5. After the catalyst has settled, filter it by pressure and then place it in a vacuum drying oven and dry it under vacuum at 70°C for 16 hours.

[0065] 6. Place the dried catalyst in a calcination furnace and then perform heat treatment. In stage 1, heat to 150°C at a heating rate of 5°C / min, and then heat treat at this temperature for 60 minutes. Then, continue heating to 300°C at a heating rate of 5°C / min and heat treat for 90 minutes. Finally, continue heating to 450°C at a heating rate of 5°C / min and heat treat for 120 minutes. After natural cooling, the desired catalyst is obtained and labeled as Pd. 0.7 -Ir 0.3 / C-450.

[0066] Example 4

[0067] 1. Dissolve iridium acetate in deionized water to prepare a 10wt% iridium acetate aqueous solution; dissolve palladium acetate in acetone to prepare a 10wt% palladium acetate acetone solution; weigh 1.84g of iridium acetate aqueous solution and 2.1g of palladium acetate acetone solution, with an iridium to palladium metal mass ratio of 1:1, and disperse in a sand mill for 30 minutes.

[0068] 2. Dissolve sodium carbonate in an aqueous solution to prepare a 20% sodium carbonate aqueous solution; weigh 0.8g of EC300J carbon black and 160g of ethanol into a beaker, add 20g of the 20% sodium carbonate aqueous solution and 1g of formic acid as a reducing agent; then place the mixed solution in a sand mill and disperse it for 120 minutes.

[0069] 3. Transfer the well dispersed carbon black mixture to a three-necked flask, place it in a water bath, set the reaction temperature of the water bath to 80℃, and stir magnetically; set the flow rate of the peristaltic pump to 5ml / min, and add the palladium and iridium precursor mixture dropwise to the three-necked flask during the reaction; after all the transfer is completed, continue the reaction for 6 hours.

[0070] 4. Allow the reacted solution to cool naturally, then transfer it to a large beaker, add 2g of pure sulfuric acid (98% by mass), then add a large amount of deionized water, stir and allow the mixture to settle naturally.

[0071] 5. After the catalyst has settled, filter it by pressure and then place it in a vacuum drying oven and dry it under vacuum at 70°C for 16 hours.

[0072] 6. Place the dried catalyst in a calcination furnace and then perform heat treatment. In stage 1, heat to 200°C at a heating rate of 5°C / min, and then heat treat at this temperature for 60 minutes. Then, continue heating to 250°C at a heating rate of 5°C / min and heat treat for 90 minutes. Finally, continue heating to 450°C at a heating rate of 5°C / min and heat treat for 120 minutes. After natural cooling, the desired catalyst is obtained and labeled as Pd. 0.5 -Ir 0.5 / C-450.

[0073] Example 5

[0074] 1. Dissolve iridium acetate in deionized water to prepare a 10wt% iridium acetate aqueous solution; dissolve palladium acetate in acetone to prepare a 10wt% palladium acetate acetone solution; weigh 1.84g of iridium acetate aqueous solution and 2.1g of palladium acetate acetone solution, with an iridium to palladium metal mass ratio of 1:1, and disperse in a sand mill for 30 minutes.

[0075] 2. Dissolve sodium carbonate in an aqueous solution to prepare a 20% sodium carbonate aqueous solution; weigh 0.8g of EC300J carbon black and 160g of ethanol into a beaker, add 20g of the 20% sodium carbonate aqueous solution and 1g of formic acid as a reducing agent; then place the mixed solution in a sand mill and disperse it for 120 minutes.

[0076] 3. Transfer the well dispersed carbon black mixture to a three-necked flask, place it in a water bath, set the reaction temperature of the water bath to 80℃, and stir magnetically; set the flow rate of the peristaltic pump to 5ml / min, and add the palladium and iridium precursor mixture dropwise to the three-necked flask during the reaction; after all the transfer is completed, continue the reaction for 6 hours.

[0077] 4. Allow the reacted solution to cool naturally, then transfer it to a large beaker, add 2g of pure sulfuric acid (98% by mass), then add a large amount of deionized water, stir and allow the mixture to settle naturally.

[0078] 5. After the catalyst has settled, filter it by pressure and then place it in a vacuum drying oven and dry it under vacuum at 70°C for 16 hours.

[0079] 6. Place the dried catalyst in a calcination furnace and then perform heat treatment. In stage 1, heat to 200°C at a heating rate of 5°C / min, and then heat treat at this temperature for 60 minutes. Then, continue heating to 250°C at a heating rate of 5°C / min and heat treat for 90 minutes. Finally, continue heating to 500°C at a heating rate of 5°C / min and heat treat for 120 minutes. After natural cooling, the desired catalyst is obtained and labeled as Pd.0.5 -Ir 0.5 / C-500;

[0080] Example 6

[0081] 1. Dissolve iridium acetate in deionized water to prepare a 10wt% iridium acetate aqueous solution; dissolve palladium acetate in acetone to prepare a 10wt% palladium acetate acetone solution; weigh 1.84g of iridium acetate aqueous solution and 2.1g of palladium acetate acetone solution, with an iridium to palladium metal mass ratio of 1:1, and disperse in a sand mill for 30 minutes.

[0082] 2. Dissolve sodium carbonate in an aqueous solution to prepare a 20% sodium carbonate aqueous solution; weigh 0.8g of EC300J carbon black and 160g of ethanol into a beaker, add 20g of the 20% sodium carbonate aqueous solution and 1g of formic acid as a reducing agent; then place the mixed solution in a sand mill and disperse it for 120 minutes.

[0083] 3. Transfer the well dispersed carbon black mixture to a three-necked flask, place it in a water bath, set the reaction temperature of the water bath to 80℃, and stir magnetically; set the flow rate of the peristaltic pump to 5ml / min, and add the palladium and iridium precursor mixture dropwise to the three-necked flask during the reaction; after all the transfer is completed, continue the reaction for 6 hours.

[0084] 4. Allow the reacted solution to cool naturally, then transfer it to a large beaker, add 2g of pure sulfuric acid (98% by mass), then add a large amount of deionized water, stir and allow the mixture to settle naturally.

[0085] 5. After the catalyst has settled, filter it by pressure and then place it in a vacuum drying oven and dry it under vacuum at 70°C for 16 hours.

[0086] 6. Place the dried catalyst in a calcination furnace and then perform heat treatment. In stage 1, heat to 200°C at a heating rate of 5°C / min, and then heat treat at this temperature for 60 minutes. Then, continue heating to 250°C at a heating rate of 5°C / min and heat treat for 90 minutes. Finally, continue heating to 550°C at a heating rate of 5°C / min and heat treat for 120 minutes. After natural cooling, the desired catalyst is obtained and labeled as Pd. 0.5 -Ir 0.5 / C-550.

[0087] Comparative Example 1

[0088] 1. Dissolve iridium acetate in deionized water to prepare a 10wt% iridium acetate aqueous solution; dissolve palladium acetate in acetone to prepare a 10wt% palladium acetate acetone solution; weigh 1.84g of iridium acetate aqueous solution and 2.1g of palladium acetate acetone solution, with an iridium to palladium metal mass ratio of 1:1, and disperse in a sand mill for 30 minutes.

[0089] 2. Dissolve sodium carbonate in an aqueous solution to prepare a 20% sodium carbonate aqueous solution; weigh 160g of ethanol into a beaker, add 20g of the 20% sodium carbonate aqueous solution and 1g of formic acid as a reducing agent; then place the mixed solution in a sand mill and disperse it for 120 minutes.

[0090] 3. Transfer the well dispersed mixture to a three-necked flask, place it in a water bath, set the reaction temperature of the water bath to 80℃, and stir magnetically; set the flow rate of the peristaltic pump to 5ml / min, and add the palladium and iridium precursor mixture dropwise to the three-necked flask during the reaction; after all the transfer is completed, continue the reaction for 6 hours.

[0091] 4. Allow the reacted solution to cool naturally, then transfer it to a large beaker, add 2g of pure sulfuric acid (98% by mass), then add a large amount of deionized water, stir and allow the mixture to settle naturally.

[0092] 5. After the catalyst has settled, filter it by pressure and then place it in a vacuum drying oven and dry it under vacuum at 70°C for 16 hours.

[0093] 6. Place the dried catalyst in a calcination furnace and then perform heat treatment. In stage 1, heat to 150°C at a heating rate of 5°C / min, and then heat treat at this temperature for 60 minutes. Then, continue heating to 300°C at a heating rate of 5°C / min and heat treat for 90 minutes. Finally, continue heating to 450°C at a heating rate of 5°C / min and heat treat for 120 minutes. After natural cooling, the desired catalyst is obtained and labeled as Pd. 0.5 -Ir 0.5 -450.

[0094] Detection Example 1

[0095] The catalysts prepared in Examples 1-6 and Comparative Example 1 were subjected to electrochemical performance tests under the same conditions. The test method was as follows: 5 mg of catalyst was accurately weighed into a 50 mL brown glass bottle, and 5 mL of a prepared Nafion isopropanol solution (Nafion mass fraction of 0.13%) was added to the weighed catalyst; the mixture was ultrasonically sonicated for 30 min to ensure uniform mixing; 5 μL of the dispersed slurry was transferred by pipette and evenly dropped onto the surface of a smooth and clean disc electrode, which was then completely dried under an infrared lamp to serve as the working electrode; the electrode was placed in an electrolytic cell to form a three-electrode system. The reference electrode was a calomel electrode, the counter electrode was a Pt wire electrode, and the electrolyte was a 0.5 mol / L H₂SO₄ solution saturated with O₂.

[0096] Under constant temperature of 25℃, the catalyst-coated working electrode was immersed in the electrolyte. Cyclic voltammetry was performed at 200 mV / s to activate the electrode. Then, the disk electrode rotation speed was adjusted to 1600 rpm, and the scan rate was changed to 5 mV / s to scan from low to high potential. Each sample was tested three times. The test voltage range was 1.0–1.6 V (Vs RHE). The RHE electrode is a reversible hydrogen electrode, a common electrode in electrochemical testing. Readouts were taken at 10 mA / cm². 2 The oxygen evolution reaction (OER) activity of the catalyst is specifically evaluated by measuring the voltage value at the current density. The test results are as follows: Figure 1 As shown.

[0097] As shown in the test spectra, the OER performance of catalysts in Examples 1-5 is superior to that of catalyst in Comparative Example 1, compared to Comparative Example 1. Calculations show that at 10 mA / cm², the OER performance is significantly better. 2 At the specified current density, Example 3 showed 345 mV (relative to RHE), while Comparative Example 1 showed 395 mV (relative to RHE), representing a 50 mV reduction in overpotential. This indicates that the Pd prepared in Example 4... 0.5 -Ir 0.5 The C-450 catalyst has better OER performance.

[0098] In water electrolysis, catalyst performance is generally related to its structure, particle size, and degree of dispersion. For Comparative Example 1, the reduction of palladium-iridium bimetal by liquid phase followed by high-temperature heat treatment may lead to agglomeration during the preparation process, resulting in larger metal particles with poor particle size uniformity. In contrast, Examples 1-4 load the bimetal onto a carbon support. Through the high specific surface area of ​​the support and the interaction between the support and the metal, the palladium-iridium metal particles are highly dispersed, with no obvious agglomeration and smaller particle size. This exposes more active sites during water electrolysis, thereby improving its OER activity.

[0099] Detection Example 2

[0100] The catalysts prepared in Example 4 and Comparative Example 1 were subjected to a chronocurrent durability test under the same conditions. The working electrode of the catalyst was coated according to the above method. Under a constant temperature of 25°C, the catalyst-coated working electrode was immersed in a 0.5 mol / L H₂SO₄ solution electrolyte, and the rotation speed of the disc electrode was adjusted to 1600 rpm. The chronocurrent working voltage was set to 1.65 V (relative to the RHE electrode), and the time was 6 hours. The change of the working electrode current over time under constant voltage conditions was investigated. The results are as follows: Figure 2 As shown.

[0101] As shown in the figure, the initial operating currents of Example 4 and Comparative Example 1 are different. Example 4 has superior OER activity, resulting in a significantly larger initial operating current than the catalyst in Comparative Example 1. Under constant voltage, the operating currents of both catalysts gradually decrease. In Comparative Example 1, the operating current tends to level off after about 5000 s, indicating that its activity has significantly decreased. However, in Example 4, the operating current only nearly coincides with that of Comparative Example 1 after 1800 s of constant voltage treatment. The constant voltage treatment time is significantly better than that of the catalyst in Comparative Example 1, indicating that the catalyst prepared in this invention has better water electrolysis stability than Comparative Example 1.

[0102] Detection Example 3

[0103] The catalysts prepared in Example 4 and Comparative Example 1 were subjected to SEM material physical characterization under the same conditions, and the results are as follows. Figures 3-6 As shown.

[0104] Depend on Figure 3 and Figure 5 It can be seen that, under the same electron microscope magnification, Example 4 has better metal dispersion and smaller particle size compared to Comparative Example 1; Comparative Example 1 appears as a certain sheet shape under the lens, which is different from the granular shape of Example 4.

[0105] exist Figure 4 In Example 4, a certain number of spherical particles appeared in the sponge-like structure, which may be due to the amorphous transformation of iridium oxide under high-temperature treatment; while Figure 6 In Comparative Example 1, the metal particles were almost entirely sponge-like. Related literature reports that iridium oxides are mainly composed of both amorphous and crystalline structures. Crystalline structures are mostly in a rutile state, exhibiting higher durability compared to amorphous amorphous iridium oxides. Amorphous iridium oxides possess more unsaturated bonds, which is beneficial for reactant adsorption. During water electrolysis, amorphous and crystalline iridium oxides coexist in a certain proportion; under their combined action, iridium... 3+ Ir 4+ and Ir 5+ The cyclical transformation enables a rapid OER process.

Claims

1. A method for preparing a bimetallic catalyst for hydrogen production by water electrolysis, characterized in that, Includes the following steps: (1) Dissolve the iridium precursor in solvent 1 to obtain an iridium precursor solution, dissolve the palladium precursor in solvent 2 to obtain a palladium precursor solution, mix and disperse the obtained iridium precursor solution and palladium precursor solution evenly to obtain mixed solution A; in mixed solution A, the mass ratio of palladium metal to iridium metal is 1:1-5; (2) Disperse carbon black, organic alcohol, alkaline solution and reducing agent evenly to obtain mixed solution B; (3) Add the mixed solution A obtained in step (1) to the mixed solution B obtained in step (2) to carry out the reduction reaction. After the reaction is completed, the reaction solution is obtained. (4) Add acid to the reaction solution in step (3) to obtain the reaction solid; (5) The reaction solids in step (4) are subjected to step heating and calcination to obtain the bimetallic catalyst for hydrogen production by water electrolysis; The stepped heating and calcination process is divided into three stages: Stage 1: Heat to 100-200℃ at a rate of 5-10℃, and heat treat for 30-90 minutes. Stage 2: Increase the temperature to 250-350℃ at a rate of 5-10℃, and heat treat for 60-120 minutes. Stage 3: Heat to 400-600℃ at a heating rate of 5-10℃, heat treat for 90-180 min, and then cool; In step (1), the mass ratios of iridium and palladium metal to carbon black, alkali solution, and reducing agent in step (2) are 1:1-10, 1:50-200, and 1:1-10, respectively.

2. The method for preparing the bimetallic catalyst for hydrogen production by water electrolysis as described in claim 1, characterized in that, In step (1), the iridium precursor is chloroiridium acid, iridium acetylacetonate, or iridium acetate. Solvent 1 is water. The iridium precursor solution has a mass fraction of 5%-20%. The palladium precursor is palladium acetate. Solvent 2 is acetone. The palladium precursor solution has a mass fraction of 5%-20%.

3. The method for preparing the bimetallic catalyst for hydrogen production by water electrolysis as described in claim 1, characterized in that, In step (2), the carbon black is BP2000, EC300J, or Cabot FCX800. The organic alcohol is at least one selected from ethanol, isopropanol, and ethylene glycol. The mass ratio of the carbon black to the organic alcohol is 1:100-400. The alkaline solution is at least one selected from sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, and sodium hydroxide aqueous solution, and the mass fraction of the alkaline solution is 10%-25%. The reducing agent is at least one of methanol, formaldehyde, and formic acid.

4. The method for preparing the bimetallic catalyst for hydrogen production by water electrolysis as described in claim 1, characterized in that, In step (3), the dropping rate is 5-20 ml / min, the temperature of the reduction reaction is 70-90℃, and the reaction time is 3-9 h.

5. The method for preparing the bimetallic catalyst for hydrogen production by water electrolysis as described in claim 1, characterized in that, In step (4), the acid solution is at least one of sulfuric acid, nitric acid, and phosphoric acid. In step (1), the mass ratio of iridium and palladium metal to the acid solution in step (4) is 1:10-20.

6. The bimetallic catalyst for hydrogen production by water electrolysis prepared by any one of the preparation methods described in claims 1 to 5.

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