PEM ternary alloy catalyst for producing hydrogen by electrolyzing water and preparation method of PEM ternary alloy catalyst

Abstract

The invention relates to a PEM ternary alloy catalyst for water electrolysis hydrogen production and a preparation method thereof, and belongs to the technical field of water electrolysis catalysts. 1-butyl-3-methylimidazolium tetrafluoroborate is introduced in the generation of a carrier manganese dioxide to increase the specific surface area of the carrier, fluorine doping and oxygen vacancy construction are realized on the surface of the carrier through hydrofluoric acid treatment, and then a metal precursor is dispersed through an ethylene glycol / water system; and finally, loading and alloying of the alloy nanoparticles are completed through hydrothermal reduction and heat treatment. The morphology and electronic structure of the carrier are synergistically regulated and controlled through ionic liquid and fluorine doping, the specific surface area and active sites are remarkably increased, strong interaction of metal and the carrier is achieved through ternary alloy component optimization, and the oxygen evolution reaction activity and stability of the catalyst and the precious metal utilization rate are effectively improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water electrolysis catalysts, and relates to a PEM ternary alloy catalyst for water electrolysis hydrogen production and a preparation method thereof. BACKGROUND

[0002] Proton Exchange Membrane (PEM) water electrolysis technology is considered as one of the most promising green hydrogen production technologies due to its high efficiency, fast response speed, high hydrogen purity and other outstanding advantages. However, the commercial large-scale application of this technology still faces great challenges, and the core bottleneck is the high dependence of anode oxygen evolution reaction (OER) catalyst on iridium. The OER reaction kinetics is slow, and in the harsh operating environment of PEM electrolyzer with strong acidity and high oxidation potential, the activity and stability of the catalyst are extremely high.

[0003] At present, the commercial OER catalyst is mainly a noble metal oxide, such as iridium dioxide or ruthenium dioxide. Although the catalytic activity of the noble metal oxide is good, there are still many problems to be solved, such as high cost, insufficient stability and low activity site utilization.

[0004] In order to reduce the dependence on iridium and improve the performance, researchers disperse and load high-activity noble metal nanoparticles on carriers with large specific surface area, aiming to reduce the amount of noble metal, improve dispersion and prevent agglomeration. The commonly used carriers include conductive carbon materials and metal oxides. However, carbon materials are easily corroded at high anode potential, causing the detachment and deactivation of the loaded metal particles; and most metal oxide carriers have poor electrical conductivity and low specific surface area, limiting electron transport and reducing the exposure of active sites.

[0005] Therefore, it is urgent to develop a PEM ternary alloy catalyst for water electrolysis hydrogen production with high activity and high stability and a preparation method thereof. SUMMARY

[0006] The purpose of the present application is to provide a PEM ternary alloy catalyst for water electrolysis hydrogen production and a preparation method thereof, which has the characteristics of low cost, high activity and high stability.

[0007] The purpose of the present application can be achieved by the following technical solutions: A preparation method of a PEM ternary alloy catalyst for water electrolysis hydrogen production, the specific steps of the preparation method are as follows, S1: 1-butyl-3-methylimidazolium tetrafluoroborate is added to a 1 M potassium permanganate solution to form solution A, manganese sulfate is dissolved in deionized water to obtain solution B, solution A is heated to 80-95 ℃ and added dropwise to solution B, the temperature is maintained and stirred for 10-20 min, 0.2 M sulfuric acid is added dropwise to adjust the pH of the mixed solution to 2-3, and stirring is continued for 1-2 h, and then deionized water and anhydrous ethanol are used for washing, and vacuum drying at 60-80 ℃ for 10-12 h to obtain powder C; S2: Powder C is dispersed in a 0.2 M hydrofluoric acid solution to obtain a solid-liquid mass ratio of (1-2):100, and refluxed at 80 ℃ for 6-8 h, and then washed with deionized water until neutral, and then heat treated at 350-400 ℃ for 2 h to obtain powder D; S3: chloroiridic acid, ruthenium trichloride and cobalt chloride are added to a mixed solvent of ethylene glycol and water, sodium citrate is added, and ultrasonic treatment is performed for 30-60 min to obtain solution E; S4: Powder E is dispersed in ethylene glycol to obtain a solid-liquid mass ratio of (1-3):50, and ultrasonic treatment is performed for 1-2 h, and then solution D is added dropwise, and ultrasonic treatment is continued for 30-60 min, and then the mixture is transferred to a high-pressure reaction kettle, and hydrothermal reaction is performed at 180-190 ℃ for 6-8 h, and then the powder is transferred to a tube furnace, and reaction is performed at 300-350 ℃ for 1-2 h to obtain the PEM ternary alloy catalyst.

[0008] As a preferred technical solution of the present application, the molar ratio of potassium permanganate to manganese sulfate in S1 is (1.2-1.5):1.

[0009] As a preferred technical solution of the present application, the addition amount of 1-butyl-3-methylimidazolium tetrafluoroborate in S1 is 10%-20% of the volume of the potassium permanganate solution.

[0010] As a preferred technical solution of the present application, the dropwise addition rate of solution A in S1 is 0.5-2 mL / min.

[0011] As a preferred technical solution of the present application, the heat treatment in S2 is performed under a nitrogen atmosphere.

[0012] As a preferred technical solution of the present application, the atomic ratio of Ir, Ru and Co in S3 is (3-5):(1-2):(5-7).

[0013] As a preferred technical solution of the present application, the volume ratio of ethylene glycol to water in S3 is 1:1.

[0014] As a preferred technical solution of the present application, the molar ratio of metal to sodium citrate in S3 is 1:(2-3).

[0015] As a preferred technical solution of the present application, the dropping speed of solution D in S4 is 1-1.5 mL / min.

[0016] As a preferred technical solution of the present application, the tube furnace atmosphere in S4 is 10% H2 / Ar.

[0017] Traditional aqueous phase reaction is difficult to accurately control the crystal morphology and defect density of manganese dioxide, resulting in insufficient exposure of active sites. In the present application, 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid is introduced, and the imidazole ring in the ionic liquid can be adsorbed on the manganese dioxide crystal surface through π-π interaction, inhibiting growth in a specific direction. The specific surface area of manganese dioxide synthesized by traditional aqueous phase is increased by more than 3 times. - BF4 in the ionic liquid can be embedded in the manganese dioxide lattice, introducing oxygen vacancies. Oxygen vacancies can optimize the adsorption / desorption energy of the catalyst surface to the reaction intermediates, reduce the reaction energy barrier, and enhance the intrinsic electronic conductivity of the material, providing excellent intrinsic electrocatalytic activity for the catalyst.

[0018] Using hydrofluoric acid reflux treatment, deep bulk doping of fluorine elements is realized, partially replacing O sites in the manganese dioxide lattice. The introduction of fluorine elements can stabilize the crystal structure, significantly enhance the chemical stability of the carrier in the harsh environment of strong acidity and high oxidation potential in the PEM electrolysis cell, effectively prevent the dissolution and corrosion of the manganese dioxide carrier, thereby prolonging the service life of the catalyst. In addition, fluorine doping can adjust the energy band structure of manganese dioxide, increase the charge carrier concentration, and greatly improve the electronic conductivity of the carrier, so that electrons can be quickly transferred from the active site during the catalytic reaction, reducing the interface resistance and improving the catalytic efficiency. The subsequent heat treatment process can remove the surface adsorbed impurities, make the crystal type more perfect, and make the distribution of fluorine elements in the lattice more uniform.

[0019] The glycol / water mixed solvent and sodium citrate as a stabilizer and dispersant are used to ensure the uniform mixing and stability of the metal precursor. The hydrothermal method uses the reducing property of glycol to firstly reduce the metal salt and uniformly attach it on the carrier surface, thereby realizing the high dispersion of the active metal. The subsequent tube furnace heat treatment completes the interdiffusion and alloying of metal atoms in a reducing atmosphere, thereby forming the ternary alloy nanoparticles with uniform composition. The Ir, Ru and Co ternary metals have a synergistic effect. The Ir has extremely high chemical stability in an acidic environment, can effectively inhibit the oxidation and dissolution of the metal in the electrolysis process, and has moderate d-band center position, which can stably adsorb the oxygen-containing intermediate and avoid the poisoning of the active sites caused by excessive adsorption. The d-band center of Ru is closer to the Fermi level, and the adsorption of the oxygen-containing intermediate is stronger, thereby having extremely high theoretical OER activity. The introduction of Ru can significantly reduce the overall overpotential, and the oxidation resistance of Ir can wrap the Ru particles to inhibit the dissolution. The introduction of Co can significantly reduce the cost, adjust the d-band center position of the Ir-Ru alloy, weaken the adsorption strength of OH, and enhance the desorption ability of OOH, thereby optimizing the OER reaction path. In addition, the surface segregation of Co can form an active interface. The Co acts as an adsorption site to promote the rapid adsorption of OH, and the Ir / Ru acts as a desorption site to accelerate the release of O2. After the three form an alloy, the best balance between activity and stability is achieved.

[0020] In the present application, the proportion of the ternary metal reduces the total content of the noble metal from 80-90% of the traditional catalyst to below 50%, and the low-cost transition metal Co becomes the main component. Not only the raw material cost is greatly reduced, but also the alloy phase formed by the noble metal and Co maximizes the utilization efficiency of the noble metal atoms, achieves the effect of obtaining better performance with the lowest noble metal loading, and is beneficial to the large-scale commercial application of the PEM water electrolysis technology.

[0021] The abundant oxygen vacancies and fluorine-doped sites on the carrier surface become ideal sites for anchoring metal atoms, and strong electronic interactions are generated with Ir, Ru, Co and other metal atoms. This metal-carrier strong interaction effect not only stabilizes the metal nanoparticles, prevents them from falling off, migrating and growing during the reaction process, but also adjusts the electronic structure of the alloy particles through the electronic effect, optimizes the adsorption strength of the reaction intermediates, and thereby synergistically improves the catalytic activity and stability.

[0022] The beneficial effects of the present application are: In the synthesis of manganese dioxide, 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid is introduced, the imidazole ring regulates the morphology of manganese dioxide through π-π interaction, and the specific surface area is significantly improved; BF4 -The embedded crystal lattice generates high concentration of oxygen vacancies, optimizes adsorption energy of reaction intermediates, enhances electronic conductivity, and reduces HER overpotential; fluorine doping is realized by hydrofluoric acid reflux, which significantly enhances the stability of the carrier in an acidic environment, prevents dissolution corrosion, and further improves the conductivity; the ethylene glycol / water system and sodium citrate are used to ensure uniform dispersion of the metal precursor, and the hydrothermal reduction and heat treatment form ternary alloy nanoparticles with uniform composition. The oxygen vacancies and fluorine doping sites on the surface of the carrier have strong interaction with the metal particles, not only stabilizing the nanostructure to prevent agglomeration, but also adjusting the electronic structure of the alloy through the electronic effect, which synergistically improves the catalytic activity and stability, and greatly prolongs the service life of the catalyst. DETAILED DESCRIPTION

[0023] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined object, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in combination with examples.

[0024] Example 1 A preparation method of a PEM ternary alloy catalyst for electrolytic water hydrogen production, the specific steps of the preparation method are as follows, S1: 1-butyl-3-methylimidazolium tetrafluoroborate is added to a 1 M potassium permanganate solution to form solution A, the addition amount of 1-butyl-3-methylimidazolium tetrafluoroborate is 15% of the volume of the potassium permanganate solution, manganese sulfate is dissolved in deionized water to obtain solution B, solution A is heated to 85 ℃ and added to solution B at a rate of 1.25 mL / min, wherein the molar ratio of potassium permanganate to manganese sulfate is 1.3:1, the temperature is maintained for 15 min with stirring, 0.2 M sulfuric acid is added to adjust the pH of the mixed solution to 2.5, and stirring is continued for 1.5 h, then deionized water and anhydrous ethanol are used for washing, and it is placed in a vacuum dryer at 70 ℃ for 11 h to obtain powder C; S2: powder C is dispersed in a 0.2 M hydrofluoric acid solution to obtain a solid-liquid mass ratio of 1.5:100, refluxed at 80 ℃ for 7 h, washed to neutral with deionized water, and heat treated at 380 ℃ in a nitrogen atmosphere for 2 h to obtain powder D; S3: chloroiridic acid, ruthenium trichloride and cobalt chloride are added to a mixed solvent of ethylene glycol and water, the volume ratio of ethylene glycol to water is 1:1, the atomic ratio of Ir, Ru and Co is 4:1.5:6, sodium citrate is added, the molar ratio of metal to sodium citrate is 1:2.5, and ultrasonic treatment is performed for 45 min to obtain solution E; S4: disperse powder E in ethylene glycol to make the solid-liquid mass ratio 1:25, ultrasonic for 1.5 h, drop solution D at a rate of 1.25 mL / min, continue to ultrasonic for 45 min, transfer the mixture to a high-pressure reaction kettle, hydrothermal reaction at 185 ℃ for 7 h, then transfer the powder to a tube furnace, reaction in 10% H2 / Ar atmosphere at 330 ℃ for 1.5 h, to obtain the PEM ternary alloy catalyst.

[0025] Example 2 A preparation method of a PEM ternary alloy catalyst for hydrogen production by electrolysis of water, the specific steps of the preparation method are as follows, S1: add 1-butyl-3-methylimidazolium tetrafluoroborate to 1 M potassium permanganate solution to form solution A, the addition amount of 1-butyl-3-methylimidazolium tetrafluoroborate is 10% of the volume of potassium permanganate solution, dissolve manganese sulfate in deionized water to obtain solution B, heat solution A to 80 ℃ and drop it into solution B at a rate of 0.5 mL / min, wherein the molar ratio of potassium permanganate to manganese sulfate is 1.2:1, maintain the temperature and stir for 10 min, adjust the pH of the mixed solution to 2 by dropping 0.2 M sulfuric acid, continue to stir for 1 h, wash with deionized water and anhydrous ethanol in turn, and place in a vacuum dryer at 60 ℃ for 10 h to obtain powder C; S2: disperse powder C in 0.2 M hydrofluoric acid solution to make the solid-liquid mass ratio 1:100, reflux at 80 ℃ for 6 h, wash to neutral with deionized water, and heat treat at 350 ℃ under nitrogen atmosphere for 2 h to obtain powder D; S3: add chloroiridic acid, ruthenium trichloride and cobalt chloride to a mixed solvent of ethylene glycol and water, the volume ratio of ethylene glycol to water is 1:1, the atomic ratio of Ir, Ru and Co is 3:1:5, add sodium citrate, the molar ratio of metal to sodium citrate is 1:2, ultrasonic treat for 30 min to obtain solution E; S4: disperse powder E in ethylene glycol to make the solid-liquid mass ratio 1:50, ultrasonic for 1 h, drop solution D at a rate of 1 mL / min, continue to ultrasonic for 30 min, transfer the mixture to a high-pressure reaction kettle, hydrothermal reaction at 180 ℃ for 6 h, then transfer the powder to a tube furnace, reaction in 10% H2 / Ar atmosphere at 300 ℃ for 1 h, to obtain the PEM ternary alloy catalyst.

[0026] Example 3 A preparation method of a PEM ternary alloy catalyst for hydrogen production by electrolysis of water, the specific steps of the preparation method are as follows, S1: 1-butyl-3-methylimidazolium tetrafluoroborate was added to a 1 M potassium permanganate solution to form solution A, the addition amount of 1-butyl-3-methylimidazolium tetrafluoroborate was 20% of the volume of the potassium permanganate solution, manganese sulfate was dissolved in deionized water to obtain solution B, solution A was heated to 95 ℃ and added dropwise to solution B at a rate of 2 mL / min, wherein the molar ratio of potassium permanganate to manganese sulfate was 1.5:1, the temperature was maintained for 20 min with stirring, 0.2 M sulfuric acid was added to adjust the pH of the mixed solution to 3, and stirring was continued for 2 h, and then washed with deionized water and anhydrous ethanol, and placed in a vacuum dryer at 80 ℃ for 12 h to obtain powder C; S2: Powder C was dispersed in a 0.2 M hydrofluoric acid solution to obtain a solid-liquid mass ratio of 1:50, and was treated at 80 ℃ for 8 h under reflux, washed with deionized water until neutral, and heat-treated at 400 ℃ for 2 h under a nitrogen atmosphere to obtain powder D; S3: chloroiridic acid, ruthenium trichloride and cobalt chloride were added to a mixed solvent of ethylene glycol and water, the volume ratio of ethylene glycol to water was 1:1, the atomic ratio of Ir, Ru and Co was 5:2:7, sodium citrate was added, the molar ratio of metal to sodium citrate was 1:3, and ultrasonic treatment was performed for 60 min to obtain solution E; S4: Powder E was dispersed in ethylene glycol to obtain a solid-liquid mass ratio of 3:50, and was ultrasonically treated for 2 h, solution D was added dropwise at a rate of 1.5 mL / min, and ultrasonic treatment was continued for 60 min, and then the mixture was transferred to a high-pressure reaction kettle and hydrothermally reacted at 190 ℃ for 8 h, and then the powder was transferred to a tube furnace and reacted at 350 ℃ for 2 h under a 10% H2 / Ar atmosphere to obtain the PEM ternary alloy catalyst.

[0027] Comparative Example 1 In S1, 1-butyl-3-methylimidazolium tetrafluoroborate was not added, and the remaining steps were the same as in Example 1.

[0028] Comparative Example 2 In S2, hydrofluoric acid was not added, and the remaining steps were the same as in Example 1.

[0029] Comparative Example 3 In S3, chloroiridic acid was not added, and the remaining steps were the same as in Example 1.

[0030] Comparative Example 4 In S3, ruthenium trichloride was not added, and the remaining steps were the same as in Example 1.

[0031] Comparative Example 5 In S3, cobalt chloride was not added, and the remaining steps were the same as in Example 1.

[0032] Comparative Example 6 In S3, only chloroiridic acid was added, and the remaining steps were consistent with Example 1.

[0033] Comparative Example 7 In S3, only ruthenium trichloride was added, and the remaining steps were consistent with Example 1.

[0034] Comparative Example 8 In S3, no sodium citrate was added, and the remaining steps were consistent with Example 1.

[0035] Comparative Example 9 In S4, no tube furnace treatment was performed, and the remaining steps were consistent with Example 1.

[0036] Electrochemical performance test The electrochemical performance test was performed using a three-electrode system, and the performance change of the oxygen evolution reaction in the electrolysis of water to produce hydrogen was evaluated. The three-electrode system was divided into a working electrode, a counter electrode, and a reference electrode, wherein the catalyst electrode was used as the working electrode, the platinum wire electrode was used as the counter electrode, the saturated silver chloride electrode was used as the reference electrode, the electrolyte was 0.5 M H2SO4 solution, and the linear scan rate was 5 mV / s.

[0037] The preparation method of the working electrode in the present application is as follows: first, 5 mg of the prepared catalyst was added to 1 mL of anhydrous ethanol, and ultrasonic treatment was performed for 20 min to form a uniformly mixed suspension. 5 μL of the suspension was taken by a pipette and dropped on a glassy carbon electrode with a diameter of 3 mm, and after drying at room temperature for 15 min, the above step was repeated once; then 5 μL of 0.2 wt% Nafion solution was taken by a pipette and dropped on the glassy carbon electrode, and after drying at room temperature, it was ready for use.

[0038] Group 10 mA / cm 2 overpotential (mV) Example 1 203 Example 2 206 Example 3 205 Comparative Example 1 245 Comparative Example 2 231 Comparative Example 3 270 Comparative Example 4 264 Comparative Example 5 235 Comparative Example 6 278 Comparative Example 7 294 Comparative Example 8 266 Comparative Example 9 273 As can be seen from the data of the examples and comparative examples, the catalyst prepared by the present application has excellent electrochemical activity.

[0039] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any simple modification, equivalent change and modification of the above embodiments made in accordance with the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis, characterized in that, The specific steps of the preparation method are as follows: S1: 1-Butyl-3-methylimidazolium tetrafluoroborate was added to a 1 M potassium permanganate solution to form solution A. Manganese sulfate was dissolved in deionized water to obtain solution B. Solution A was heated to 80-95 °C and added dropwise to solution B. The temperature was maintained and the mixture was stirred for 10-20 min. 0.2 M sulfuric acid was added dropwise to adjust the pH of the mixed solution to 2-3. The mixture was stirred for 1-2 h. The solution was washed with deionized water and anhydrous ethanol in sequence and then dried under vacuum at 60-80 °C for 10-12 h to obtain powder C. S2: Disperse powder C in 0.2 M hydrofluoric acid solution to make the solid-liquid mass ratio (1~2):100, reflux at 80 ℃ for 6~8 h, wash with deionized water until neutral, and heat treat at 350~400 ℃ for 2 h to obtain powder D; S3: Add chloroiridic acid, ruthenium trichloride and cobalt chloride to a mixed solvent of ethylene glycol and water, add sodium citrate, and sonicate for 30-60 min to obtain solution E; S4: Disperse powder E in ethylene glycol to a solid-liquid mass ratio of (1~3):50, sonicate for 1~2 h, add solution D dropwise, continue sonication for 30~60 min, transfer the mixture to a high-pressure reactor, and hydrothermally react at 180~190 ℃ for 6~8 h, then transfer the powder to a tube furnace and react at 300~350 ℃ for 1~2 h to obtain the PEM ternary alloy catalyst.

2. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The molar ratio of potassium permanganate to manganese sulfate in S1 is (1.2~1.5):

1.

3. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The amount of 1-butyl-3-methylimidazolium tetrafluoroborate added in S1 is 10% to 20% of the volume of potassium permanganate solution.

4. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The dropping rate of solution A in S1 is 0.5~2 mL / min.

5. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The heat treatment in S2 is carried out under a nitrogen atmosphere.

6. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The atomic ratio of Ir, Ru and Co in S3 is (3~5):(1~2):(5~7).

7. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, In the S3 mixture of ethylene glycol and water, the volume ratio of ethylene glycol to water is 1:

1.

8. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The molar ratio of the metal to sodium citrate in S3 is 1:(2~3).

9. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The dropping rate of solution D in S4 is 1~1.5 mL / min.

10. The method for preparing a PEM ternary alloy catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, The atmosphere of the tube furnace in S4 is 10% H2 / Ar.