An iridium selenium catalyst, its preparation method and use

Abstract

The application provides an iridium selenium catalyst and a preparation method and application thereof, and belongs to the technical field of electrocatalysis. Through a hydrothermal reaction, under the induction of a selenium source, an iridium selenium catalyst with a hollow nanosphere structure is prepared. Compared with a traditional IrO2 catalyst, the iridium selenium catalyst provided by the application releases metal atoms in the particle interior, can greatly reduce the amount of the noble metal iridium, and reduces the cost. Meanwhile, the material also has high OER activity, and has high industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, specifically relating to an iridium-selenium catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, with its advantages of being clean, renewable, and having high energy density, has become a potential environmentally friendly non-carbon energy carrier. Water electrolysis technology can convert electrical energy into hydrogen energy and is considered a clean, efficient, and sustainable hydrogen production technology, which is of great significance for achieving the sustainable use of hydrogen energy. Among renewable energy-driven water electrolysis hydrogen production technologies, proton exchange membrane electrolysis (PEMWE) is considered a potentially valuable green hydrogen production method due to its advantages such as low resistance loss, minimal gas crosstalk, high current density, and good compatibility with renewable energy sources.

[0003] However, due to the four-electron transfer process of the oxygen evolution reaction (OER), the OER process is usually slow in kinetics and has a high overpotential. At the same time, the corrosive environment of the anode means that currently only Ir-based catalysts can be used as OER catalysts in PEM that meet the requirements of catalytic activity and stability. However, the high cost and low reserves of iridium metal severely limit the large-scale application of PEMWE.

[0004] Given this issue, it is crucial to design and manufacture novel catalysts that are more efficient with low Ir loading, while also exhibiting good OER performance and being corrosion-resistant and stable. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide an iridium selenide catalyst, its preparation method, and its application. The iridium selenide catalyst significantly reduces the amount of the precious metal iridium used, while simultaneously exhibiting high OER activity.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an iridium selenide catalyst having a hollow nanosphere structure;

[0008] The iridium selenide catalyst has a particle size of 50~100 nm.

[0009] Preferably, in the iridium-selenium catalyst, the mass ratio of iridium to selenium is 1:(0.5~1).

[0010] Secondly, the present invention provides a method for preparing the above-mentioned iridium selenide catalyst, comprising the following steps:

[0011] An iridium-selenium catalyst is obtained by mixing a mixture of an iridium source, a selenium source, and a reducing agent with an alcohol-water solvent and carrying out a hydrothermal reaction.

[0012] Preferably, the iridium source is selected from any one or more of chloroiridium acid, iridium acetylacetonate, or iridium trichloride.

[0013] Preferably, the selenium source is selected from dibenzyl diselenyl ether and / or selenium dioxide.

[0014] Preferably, the reducing agent is selected from any one or more of ascorbic acid, hydrazine hydrate, or sodium dithionite.

[0015] Preferably, the alcohol-water solvent comprises water and a polyol; the polyol comprises any one or more of ethylene glycol, glycerol, 1,2-propanediol or 1,2-butanediol; and the volume ratio of water to polyol is (0.2~1):1.

[0016] Preferably, the mass ratio of the iridium source to the selenium source is 1:(0.5~2); the mass ratio of the reducing agent to the iridium source is (5~8):1.

[0017] Preferably, the mass ratio of the iridium source to the alcohol-water solvent is 1:(1000~1500).

[0018] Preferably, the hydrothermal reaction is carried out at a temperature of 160-180°C for 9-24 hours.

[0019] Preferably, the mixture is treated under ultrasonic conditions for 30-60 minutes.

[0020] Preferably, the mixture further includes a surfactant.

[0021] Preferably, the surfactant is selected from any one or more of CTAB, AEO, or PVP;

[0022] Preferably, the mass ratio of the surfactant to the iridium source is (4~10):1.

[0023] Preferably, after the hydrothermal reaction is completed, the process further includes washing, centrifugation, and drying.

[0024] Preferably, the washing is performed using a mixed solution of acetone and anhydrous ethanol, wherein the volume ratio of acetone to anhydrous ethanol is 1:(1~5).

[0025] Preferably, the drying temperature is 40~80℃ and the time is 4~12 h.

[0026] Preferably, after the hydrothermal reaction or drying is completed, a heat treatment step is also included.

[0027] Preferably, the heat treatment temperature is 300~500℃ and the time is 2~8 h.

[0028] Thirdly, the present invention provides an application of the above-mentioned iridium selenide catalyst as an acidic oxygen evolution reaction catalyst in proton exchange membrane electrolysis of water.

[0029] Preferably, the iridium selenide catalyst is used as a catalyst for the acidic oxygen evolution reaction at a loading of 0.5~1 mg / cm³. 2 .

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] This invention prepares an iridium-selenium catalyst with a hollow nanosphere structure through a hydrothermal reaction induced by a selenium source. Compared with traditional IrO2 catalysts, the iridium-selenium catalyst provided by this invention, due to its unique hollow structure, releases the metal atoms inside the particles, significantly reducing the amount of precious iridium used and lowering costs. Simultaneously, compared with commercial IrO2 catalysts of the same loading, this material exhibits a lower voltage at the same current density and higher OER activity, showing great promise for industrial applications. Attached Figure Description

[0032] Figure 1 The image shows a TEM image of the iridium selenide catalyst obtained in Example 1.

[0033] Figure 2 The image shows the iridium selenide catalyst obtained in Example 2 before heat treatment, as a TEM image.

[0034] Figure 3 The image shows a TEM image of the iridium selenide catalyst obtained in Example 2 after heat treatment.

[0035] Figure 4 The figures show the catalytic test results of the iridium selenide catalyst obtained in Example 2 before and after heat treatment, and the catalytic test results of Maclean's commercial IrO2 catalyst.

[0036] Figure 5 The image shows a TEM image of the iridium selenide catalyst obtained in Example 3.

[0037] Figure 6 The image shows a TEM image of the iridium selenide catalyst obtained in Example 4.

[0038] Figure 7 The image shows a TEM image of the iridium nanoparticles obtained in Comparative Example 1.

[0039] Figure 8 The image shows a TEM image of the iridium selenide catalyst obtained in Comparative Example 2. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] To address the issue of high cost due to the high Ir loading in existing Ir-based catalysts, this invention provides an iridium-selenium catalyst with a hollow nanosphere structure, approximately IrSe2. Characterization shows that the particle size of the iridium-selenium catalyst is 50-100 nm, such as 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.

[0042] In this invention, the mass ratio of iridium to selenium in the iridium-selenium catalyst is 1:(0.5~1), preferably 1:(0.8~1).

[0043] The present invention also provides a method for preparing the above-mentioned iridium selenide catalyst, which includes the following steps:

[0044] An iridium-selenium catalyst is obtained by mixing a mixture of an iridium source, a selenium source, and a reducing agent with an alcohol-water solvent and carrying out a hydrothermal reaction.

[0045] According to the present invention, a mixture of an iridium source, a selenium source, and a reducing agent is first provided.

[0046] In some embodiments of the present invention, it is preferred to mix an iridium source, a selenium source, and a reducing agent to obtain a mixture. The iridium source is selected from any one or more of chloroiridium acid, iridium acetylacetonate, or iridium trichloride; the selenium source is selected from dibenzyldiselenoether and / or selenium dioxide; the reducing agent is selected from any one or more of ascorbic acid (AA), hydrazine hydrate, or sodium dithionite. The mass ratio of the iridium source to the selenium source is 1:(0.5~2), such as 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, or 1:2, etc.; the mass ratio of the reducing agent to the iridium source is (5~8):1, such as 5:1, 6:1, 7:1, or 8:1, etc.

[0047] In this invention, the above mixing is preferably carried out at room temperature. During the mixing process, the reducing agent reduces the polyvalent selenium in the selenium source to zero-valent selenium, which is beneficial for the subsequent hydrothermal reaction to form a hollow nanosphere structure. It should be noted that hydrazine hydrate poses a certain risk during the hydrothermal process when used as the reducing agent. Therefore, the reducing agent is more preferably ascorbic acid (AA) and / or sodium dithionite, with ascorbic acid being the most preferred.

[0048] After obtaining the above mixture, according to the present invention, it is preferable to add the above mixture to an alcohol-water solvent for mixing. The mixing is preferably carried out in an ultrasonic environment for 30 to 60 minutes, such as 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes or 60 minutes, to ensure uniform mixing.

[0049] In this invention, the alcohol-water solvent comprises water and a polyol (the polyol can act as a reducing agent; the reduction of Ir using a polyol results in a very low yield in a pure water system, and a pure polyol system will produce a solid spherical structure without a hollow structure). The water is preferably pure water, and the polyol comprises any one or more of ethylene glycol, glycerol, 1,2-propanediol, or 1,2-butanediol. The volume ratio of water to polyol is (0.2~1):1, such as 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1:1, etc.

[0050] In some embodiments of the present invention, the mass ratio of the iridium source to the alcohol-water solvent is 1:(1000~1500), such as any one or more of 1:1000, 1:1100, 1:1200, 1:1300, 1:1400 or 1:1500.

[0051] After the above mixing is completed, the resulting mixture is subjected to a hydrothermal reaction in a hydrothermal reactor according to the present invention. In some embodiments of the present invention, the temperature of the hydrothermal reaction is 160~180℃, such as 160℃, 165℃, 170℃, 175℃ or 180℃; the time is 9~24 h, such as 9 h, 12 h, 15 h, 18 h, 21 h or 24 h, etc.

[0052] In this invention, during the above-mentioned hydrothermal reaction, the alcohol-water solvent provides a certain reducing ability to assist the reduction of Ir. During the growth of nanoparticles, due to the Kirkendall effect, the diffusion and migration rates of the two types of atoms are different, gradually forming a hollow structure, and finally obtaining an iridium selenide catalyst with a hollow nanosphere structure.

[0053] In the above-mentioned technical solution provided by the present invention, the obtained iridium selenide catalyst has a hollow nanosphere structure, but the shape of its spheres is not very regular.

[0054] Therefore, the present invention further optimized the experiment by introducing a surfactant, and unexpectedly found that the spherical shape of the obtained iridium selenide catalyst was more regular.

[0055] Based on this, in some preferred embodiments of the present invention, the preparation method of the iridium selenide catalyst includes the following steps:

[0056] An iridium-selenium catalyst is obtained by mixing a mixture of iridium source, selenium source, reducing agent and surfactant with an alcohol-water solvent and carrying out a hydrothermal reaction.

[0057] The selection and dosage of the iridium source, selenium source, reducing agent, and alcohol-water solvent are as described above and will not be repeated here. This section mainly focuses on the selection and dosage of the surfactant.

[0058] In this invention, the surfactant is selected from one or more of CTAB (hexadecyltrimethylammonium bromide), AEO (fatty alcohol polyoxyethylene ether), or PVP (polyvinylpyrrolidone), preferably CTAB. The mass ratio of the surfactant to the iridium source is (4~10):1, such as 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1.

[0059] In both technical solutions of the present invention (with or without surfactant), after the hydrothermal reaction is completed, the steps of washing, centrifugation and drying are also included.

[0060] In some embodiments of the present invention, the washing is carried out using a mixed solution of acetone and anhydrous ethanol, wherein the volume ratio of acetone to anhydrous ethanol is 1:(1~5), such as 1:1, 1:2, 1:3, 1:4 or 1:5, etc.; the drying is preferably vacuum drying, the drying temperature is 40~80℃, preferably 45~75℃, and the drying time is 4~12 h, preferably 5~10 h.

[0061] In some preferred embodiments of the present invention, after the hydrothermal reaction or drying is completed, a heat treatment step in an air atmosphere is further included to remove residual surfactants on the surface and remove some selenium atoms to expose metal sites. The heat treatment temperature is 300~500℃, such as 300℃, 320℃, 350℃, 370℃, 400℃, 420℃, 450℃, 470℃, or 500℃, and the time is 2~8 hours, such as 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours.

[0062] In summary, in some preferred embodiments of the present invention, the preparation method of the iridium selenide catalyst includes the following steps:

[0063] S1: Mix the iridium source, selenium source, reducing agent, optional surfactant and alcohol-water solvent, stir and mix well, and then sonicate to disperse it evenly.

[0064] S2: The mixture obtained in step S1 is subjected to a hydrothermal reaction, and after washing, centrifugation and drying, it is subjected to heat treatment to obtain the iridium selenide catalyst.

[0065] It is evident that the preparation method of the iridium selenide catalyst provided by the present invention is simple, convenient, and easy to implement, which is conducive to large-scale or industrial production.

[0066] The present invention also provides an application of the iridium selenide catalyst involved in the above-mentioned technical solution as an acidic oxygen evolution reaction catalyst in proton exchange membrane electrolysis of water.

[0067] In the aforementioned applications, the iridium selenide catalyst is used as a catalyst for the acidic oxygen evolution reaction at a loading of 0.5–1 mg / cm³. 2 For example, it could be 0.5 mg / cm³. 2 0.6 mg / cm 2 0.7 mg / cm 2 0.8 mg / cm 2 0.9 mg / cm 2 or 1 mg / cm 2 wait.

[0068] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention are commercially available products.

[0069] Example 1

[0070] This embodiment provides an iridium selenide catalyst with a hollow nanosphere structure, and the preparation method is as follows:

[0071] 10 mg of iridium trichloride, 8 mg of selenium dioxide, and 54 mg of AA were added to 10 mL of an alcohol-water mixture of ethylene glycol and water in a 1:1 volume ratio. The mixture was ultrasonically dispersed and reacted in a hydrothermal reactor at 160 °C for 12 h. The resulting product was then washed with acetone and anhydrous ethanol in a 1:1 volume ratio, centrifuged, and dried in a vacuum oven at 55 °C for 12 h to obtain the iridium-selenium catalyst.

[0072] TEM images of the iridium selenide catalyst prepared above are as follows: Figure 1 As shown in the TEM image, the material can be seen to be a hollow nanosphere with a diameter of about 50~100 nm.

[0073] Example 2

[0074] Compared with Example 1, this embodiment uses a surfactant for assistance, and the preparation method is as follows:

[0075] 10 mg of iridium trichloride, 8 mg of selenium dioxide, 54 mg of AA, and 18 mg of CTAB were added to 10 mL of an alcohol-water mixture of ethylene glycol and water in a 1:1 volume ratio. The mixture was ultrasonically dispersed and reacted in a hydrothermal reactor at 160 °C for 12 h. The resulting product was then washed with acetone and anhydrous ethanol, centrifuged, and dried in a vacuum oven at 55 °C for 12 h to obtain the iridium-selenium catalyst. The catalyst was then subjected to high-temperature heat treatment in air at 300 °C for 5 h to remove residual surfactants and some selenium atoms to expose the metal sites.

[0076] TEM images of the iridium selenide catalyst prepared above before and after high-temperature treatment are shown below. Figure 2 and Figure 3 As shown, both the iridium selenide catalyst before and after high-temperature treatment are nanospheres with obvious hollow structures and more regular morphology, with a diameter of about 50~100 nm.

[0077] Membrane electrode preparation and testing

[0078] The iridium-selenium catalyst with hollow nanosphere structure obtained in Example 2 before and after high-temperature heat treatment was used in a PEM water electrolysis device for testing. This invention employs a two-electrode test. A commercially available platinum-carbon catalyst was used as the cathode for the hydrogen evolution reaction, and the iridium-selenium catalyst with hollow nanosphere structure obtained in Example 2 before and after high-temperature heat treatment was used as the oxygen evolution reaction. After the catalysts of the aforementioned cathode and anode were prepared into membrane electrodes using a spray-coating-pressure method, the catalyst loading at the anode was 0.5 mg / cm³. 2 They were assembled into PEM devices. Test results are as follows: Figure 4 As shown, before high-temperature heat treatment (i.e., IrSe-NPs), at 1 A / cm 2 At the current density, its potential is 1.654 V, and at 2 A / cm 2 At current density, its potential is 1.826 V, and at 3 A / cm 2 At current density, its potential is 2.032 V; after high-temperature heat treatment (i.e., IrSe-NPs-300℃), it is at 1 A / cm 2 At current density, its potential is 1.623 V, and at 2 A / cm 2 At current density, its potential is 1.759 V, and at 3 A / cm 2 At the given current density, its potential is 1.887 V; while commercial IrO2 (i.e., Macklin-IrO2) has a potential of 1 A / cm. 2 At current density, its potential is 1.737 V, and at 2 A / cm 2 At current density, its potential is 1.907 V, and at 3 A / cm 2At the current density, its potential is 2.060 V. The above results indicate that this catalyst is expected to be used as an anode oxygen evolution catalyst for PEM water electrolysis to produce hydrogen.

[0079] In summary, the iridium selenide catalyst with hollow nanosphere structure prepared in this invention exhibits good catalytic performance in PEM tests.

[0080] Example 3

[0081] 10 mg of iridium trichloride, 8 mg of selenium dioxide, 54 mg of AA and 33 mg of AEO were added to 10 mL of an alcohol-water mixture of ethylene glycol and water in a 1:1 volume ratio. The mixture was ultrasonically dispersed and reacted in a hydrothermal reactor at 160 °C for 12 h. The resulting product was then washed with acetone and anhydrous ethanol, centrifuged, and dried in a vacuum oven at 55 °C for 12 h to obtain the iridium-selenium catalyst.

[0082] TEM images of the iridium selenide catalyst prepared above are as follows: Figure 5 As shown, it can be seen that it is a nanosphere with a distinct hollow structure, with a diameter of about 50~100 nm.

[0083] Example 4

[0084] 14 mg of chloroiridium acid, 25 mg of dibenzyl diselenyl ether, and 54 mg of AA were added to 10 mL of an alcohol-water mixture of ethylene glycol and water in a 1:1 volume ratio. The mixture was ultrasonically dispersed and reacted in a hydrothermal reactor at 160 °C for 12 h. The resulting product was then washed with acetone and anhydrous ethanol, centrifuged, and dried in a vacuum oven at 55 °C for 12 h to obtain the iridium selenide catalyst.

[0085] TEM images of the iridium selenide catalyst prepared above are as follows: Figure 6 As shown, it can be seen that it is a nanosphere with a hollow structure and a diameter of about 50~100 nm.

[0086] Comparative Example 1

[0087] To demonstrate the inducing effect of selenium source on the formation of hollow nanostructures, Comparative Example 1 is used to illustrate the importance of the inducing effect of selenium source.

[0088] Preparation of iridium nanoparticles:

[0089] 10 mg of iridium trichloride, 54 mg of AA and 18 mg of CTAB were added to 10 mL of an alcohol-water mixture of ethylene glycol and water in a 1:1 volume ratio. The mixture was ultrasonically dispersed and reacted in a hydrothermal reactor at 160 °C for 12 h. The resulting product was then washed with acetone and anhydrous ethanol, centrifuged, and dried in a vacuum oven at 55 °C for 12 h to obtain iridium nanoparticles.

[0090] TEM images of the iridium nanoparticles prepared above are as follows: Figure 7 As shown, iridium nanoparticles are small-diameter nanoparticles with a sheet-like structure.

[0091] Comparative Example 2

[0092] The reaction for preparing the hollow nanosphere structured iridium selenide catalyst of this invention relies on an alcohol-water mixed solvent to form a hollow structure. To demonstrate the necessity of the alcohol-water mixed solvent, Comparative Example 2 is provided.

[0093] This comparative example provides an iridium selenide catalyst with a solid nanosphere structure, and its preparation method is as follows:

[0094] 10 mg of iridium trichloride, 8 mg of selenium dioxide, and 54 mg of AA were added to 10 mL of ethylene glycol and ultrasonically dispersed. The mixture was then reacted in a hydrothermal reactor at 160 °C for 12 h. The resulting product was then washed with acetone and anhydrous ethanol, centrifuged, and dried in a vacuum oven at 55 °C for 12 h to obtain an iridium-selenium catalyst with a hollow nanosphere structure.

[0095] TEM images of the iridium selenide catalyst prepared above are as follows: Figure 8 As shown, the iridium selenide catalyst is a solid nanoparticle.

[0096] In summary, the iridium selenide catalyst with hollow nanosphere structure prepared by this invention reduces the amount of precious metal iridium used, thereby lowering costs, while also exhibiting high OER activity. It demonstrates excellent catalytic performance in industrial PEM water electrolysis and has high prospects for industrial application.

[0097] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an iridium-selenium catalyst for acidic water electrolysis, characterized in that, Includes the following steps: The mixture of iridium source, selenium source and reducing agent is mixed with an alcohol-water solvent and subjected to a hydrothermal reaction to obtain the product. The alcohol-water solvent includes water and a polyol; the polyol includes any one or more of ethylene glycol, glycerol, 1,2-propanediol or 1,2-butanediol; the volume ratio of water to polyol is (0.2~1):

1. The iridium selenide catalyst has a hollow nanosphere structure; The iridium selenide catalyst has a particle size of 50~100 nm.

2. The preparation method according to claim 1, characterized in that, In the iridium-selenium catalyst, the mass ratio of iridium to selenium is 1:(0.5~1).

3. The preparation method according to claim 1 or 2, characterized in that, The iridium source is selected from any one or more of chloroiridium acid, iridium acetylacetonate, or iridium trichloride. The selenium source is selected from dibenzyl diselenyl ether and / or selenium dioxide; The reducing agent is selected from any one or more of ascorbic acid, hydrazine hydrate, or sodium dithionite. The mass ratio of the iridium source to the selenium source is 1:(0.5~2); the mass ratio of the reducing agent to the iridium source is (5~8):1; and the mass ratio of the iridium source to the alcohol-water solvent is 1:(1000~1500).

4. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 160~180℃ for a duration of 9~24 h. The mixture is treated under ultrasonic conditions for 30-60 minutes.

5. The preparation method according to claim 1, characterized in that, The mixture also includes a surfactant; The surfactant is selected from any one or more of CTAB, AEO, or PVP; The mass ratio of the surfactant to the iridium source is (4~10):

1.

6. The preparation method according to claim 1, characterized in that, After the hydrothermal reaction is completed, the process also includes washing, centrifugation and drying steps; The washing is carried out using a mixed solution of acetone and anhydrous ethanol, wherein the volume ratio of acetone to anhydrous ethanol is 1:(1~5). The drying temperature is 40~80℃, and the time is 4~12 h.

7. The preparation method according to claim 1, characterized in that, After the hydrothermal reaction or drying is completed, a heat treatment step is also included; The heat treatment is performed at a temperature of 300-500℃ for 2-8 hours.

8. The application of the iridium selenide catalyst prepared by any one of claims 1 to 7 as an acidic oxygen evolution reaction catalyst in proton exchange membrane water electrolysis.

9. The application according to claim 8, characterized in that, The iridium selenide catalyst, used as a catalyst for the acidic oxygen evolution reaction, has a loading of 0.5–1 mg / cm³. 2 .

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