Potassium iridate catalyst and preparation method thereof

Abstract

The invention discloses a potassium iridate catalyst and a preparation method thereof. The method comprises the following steps: dissolving an iridium source material in a first liquid to generate a first solution; adding a chelating agent into the first solution to generate a second solution; performing ultrasonic treatment and / or stirring on the second solution for a certain time to generate a third solution; adding a pro-oxidant into the third solution to generate a fourth solution, and stirring the fourth solution at a specific temperature for a certain time to obtain potassium iridate precursor powder; calcining and oxidizing the potassium iridate precursor powder to obtain an initial catalyst; and filtering and washing the initial catalyst, and heating and drying to obtain the potassium iridate catalyst. The potassium iridate catalyst is prepared by the preparation method. The potassium iridate catalyst disclosed by the invention is good in oxygen evolution performance and has ultrahigh OER electro-catalysis stability at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst materials, in particular to a potassium iridate catalyst and a preparation method thereof. Background Art

[0002] Hydrogen is an efficient clean energy carrier and a renewable energy source that can be stored in chemical form. Currently, water electrolysis is an environmentally friendly and efficient method for producing hydrogen. However, the oxygen evolution reaction (OER) on the anode side of the electrolyzer causes significant voltage loss in the cell due to slow kinetics and high overpotential. Therefore, it is of great significance to develop efficient oxygen evolution electrocatalysts. IrO2 ) is considered to be the most promising commercial catalyst. However, due to the high price and scarcity of iridium metal, it is very necessary to improve the catalytic performance of oxygen evolution reaction and reduce the catalyst load.

[0003] Currently, commercial potassium iridate catalysts usually exist in the form of amorphous nanoparticles. This irregular structure limits the catalytic performance of the material, and the utilization rate and specific surface area of ​​iridium are low. Although the existing technology uses template methods ("soft templates" or "hard templates"), electrochemical deposition, and photochemical synthesis to synthesize catalysts with special structures, such as ordered mesoporous and / or macroporous structures and nanoparticle film structures, which can improve the utilization rate of iridium (Ir) and increase the specific surface area of ​​the catalyst, the synthesis of such catalysts usually involves highly complex technology, making it difficult to expand the production scale. The use of simple and easy-to-operate methods to synthesize highly active and stable iridium-based catalysts is currently actively pursued and explored by researchers. Summary of the invention

[0004] In view of the above-mentioned technical deficiencies, the object of the present invention is to provide a potassium iridate catalyst and a preparation method thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A potassium iridate catalyst and a preparation method thereof, comprising the following steps: dissolving an iridium source material in a first liquid to generate a first solution; adding a chelating agent to the first solution to generate a second solution; subjecting the second solution to ultrasonic and / or stirring reaction for a certain period of time to generate a third solution; Adding a co-oxidant to the third solution to generate a fourth solution, and stirring the fourth solution at a specific temperature for a certain period of time to evaporate water, thereby obtaining a potassium iridate precursor powder; calcining and oxidizing the potassium iridate precursor powder to obtain an initial catalyst; The initial catalyst is filtered and washed, and then heated and dried to obtain a potassium iridate catalyst.

[0006] Furthermore, the iridium source material comprises: K2IrCl6 , H2IrCl6 , IrCl3 , IrCl4 , IrO2 , K3IrCl6 Any one or a mixture of at least two materials.

[0007] Furthermore, the chelating agent includes amino organic matter.

[0008] Furthermore, the chelating agent includes cysteamine.

[0009] Furthermore, the co-oxidant comprises a metal nitrate; the metal nitrate is a single metal nitrate or a mixture of at least two metal nitrates, and the metal contained in the metal nitrate is one of K, Na, Li, and Cu.

[0010] Furthermore, the first liquid includes deionized water and / or pure water; the second liquid includes deionized water and / or pure water.

[0011] Furthermore, the molar ratio of the iridium source material, the chelating agent and the co-oxidant is 1:(1-3000):(1-1200).

[0012] Furthermore, the step of calcining and oxidizing the potassium iridate precursor powder to obtain the initial catalyst includes: placing the potassium iridate precursor powder in a specific container, heating it to 300 to 800 degrees Celsius at a rate of 1 to 10 degrees Celsius per minute, and keeping it in air for 0.5 to 5 hours to obtain the initial catalyst.

[0013] Furthermore, the step of filtering and washing the initial catalyst, and heating and drying it to obtain the potassium iridate catalyst includes: filtering, washing and drying the initial catalyst with a second liquid to obtain the potassium iridate catalyst.

[0014] The present invention also relates to a potassium iridate catalyst, which is prepared by the above-mentioned preparation method.

[0015] The beneficial effects of the present invention are: 1. The potassium iridate catalyst prepared by the preparation method of the potassium iridate catalyst of the present invention exhibits good oxygen evolution performance, low charge transfer resistance and high oxygen evolution reaction durability in an acidic medium.

[0016] 2. The potassium iridate catalyst prepared by the preparation method of the potassium iridate catalyst of the present invention has a low overpotential.

[0017] 3. The method for preparing the potassium iridate catalyst of the present invention is convenient and efficient in the process of preparing the potassium iridate catalyst, and has good stability and reliability.

[0018] 4. The preparation method of the potassium iridate catalyst of the present invention is suitable for industrial batch synthesis and has a wide range of applications.

[0019] 5. The preparation method of the potassium iridate catalyst of the present invention can provide a better approach for the application of nano-iridate catalysts and their applications in proton exchange membrane water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the flow structure of a specific embodiment of a method for preparing a potassium iridate catalyst provided by the present invention; Figure 2 A transmission electron microscope photograph of a specific embodiment of a potassium iridate catalyst prepared by a method for preparing a potassium iridate catalyst provided by the present invention; Figure 3 A comparison chart of X-ray diffraction intensities of a potassium iridate catalyst prepared by a method for preparing a potassium iridate catalyst provided by the present invention and an Umicore iridium oxide catalyst; Figure 4 A comparison diagram of linear polarization (LSV) curves of a potassium iridate catalyst prepared by a preparation method of a potassium iridate catalyst provided by the present invention and two commercial iridium oxide catalysts. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] like Figure 1 As shown, a method for preparing a potassium iridate catalyst comprises the following steps: (1) Dissolving an iridium source material in a first liquid to generate a first solution. The mass of the iridium source material can be set according to actual needs.

[0024] (2) Adding a chelating agent to the first solution to generate a second solution. The addition of the chelating agent plays an important role in the formation of potassium iridate, so that the generated iridium-based catalyst is potassium iridate with high activity and high stability.

[0025] (3) Ultrasonication and / or stirring the second solution for a certain period of time to generate a third solution. Ultrasonication and / or stirring can fully mix the reactants in the second solution, thereby improving the mixing uniformity of the third solution.

[0026] (4) Adding a co-oxidant to the third solution to generate a fourth solution, and stirring the fourth solution at a specific temperature for a certain period of time to obtain a potassium iridate precursor powder. Adding a co-oxidant and stirring the fourth solution at a specific temperature for a certain period of time is conducive to obtaining a potassium iridate precursor powder.

[0027] (5) Calcination and oxidation of the potassium iridate precursor powder to obtain an initial catalyst. The calcination can cause the potassium iridate precursor powder to be oxidized to form a potassium iridate catalyst.

[0028] (6) Filtering and washing the initial catalyst, and heating and drying it to obtain a potassium iridate catalyst. By filtering and washing the initial catalyst, the residues or impurities in the initial catalyst can be removed, and by heating and drying it, a high-quality potassium iridate catalyst can be obtained.

[0029] Among them, by adding a chelating agent during the synthesis process, the potassium iridate catalyst can exhibit better oxygen evolution performance, lower charge transfer resistance and higher oxygen evolution reaction durability in an acidic medium.

[0030] 在一个具体的实施例中，铱源材料包括：K2IrCl6、H2IrCl6、IrCl3、IrCl4、IrO2、K3IrCl6中的任意一种或者多种材料的混合。其中，上述铱源材料的水溶性好，且不含 对催化剂有害的杂质成分，适合做铱酸钾催化剂的前驱体。

[0031] In a specific embodiment, the chelating agent includes cysteamine. Unlike the conventional Adams combustion method, cysteamine is added during the synthesis process to replace the chloride ions of the iridium source material in the complex. The results show that the addition of amino groups plays an important role in the formation of potassium iridate, and the generated potassium iridate sample exhibits good oxygen evolution performance, low charge transfer resistance and high oxygen evolution reaction durability in acidic media.

[0032] In a specific embodiment, the co-oxidant includes a metal nitrate, which can enhance the degree of oxidation of potassium iridate.

[0033] In a specific embodiment, the metal nitrate includes: any one nitrate of metal K, Na, Li, Cu or a mixture of multiple nitrates, which has a strong pro-oxidation ability.

[0034] In a specific embodiment, the first liquid includes deionized water and / or pure water with high purity.

[0035] In a specific embodiment, the molar ratio of the iridium source material, the chelating agent, and the oxidant is 1:10-300:80-120, which can facilitate the acquisition of a high-performance potassium iridate catalyst.

[0036] In a specific embodiment, the step of ultrasonically treating and / or stirring the second solution for a certain period of time to generate a third solution includes: ultrasonically treating and / or stirring the second solution for a certain period of time to generate the third solution, which can make the reactants of the second solution fully mixed, thereby better improving the mixing uniformity of the third solution.

[0037] In a specific embodiment, the step of stirring the fourth solution at a specific temperature for a certain time to obtain potassium iridate precursor powder includes: stirring the fourth solution at a certain temperature for a certain time to evaporate water to obtain potassium iridate precursor powder.

[0038] In a specific embodiment, the potassium iridate precursor powder is calcined and oxidized to obtain an initial catalyst, which includes placing the potassium iridate precursor powder in a specific container, heating it to 300 to 800 degrees Celsius at a rate of 1 to 10 degrees Celsius per minute, and keeping it in the air for a certain period of time to obtain the initial catalyst, so that the potassium iridate precursor powder can be fully calcined and fully oxidized to better obtain the initial catalyst.

[0039] In a specific embodiment, the initial catalyst is filtered and washed, and heated and dried to obtain a potassium iridate catalyst, including the steps of filtering, washing and drying the initial catalyst with a second liquid to obtain a potassium iridate catalyst. The initial catalyst is filtered and washed with the second liquid, so that residues or impurities in the initial catalyst can be better removed, and vacuum heating and drying can improve the heating and drying effect, thereby obtaining a higher quality potassium iridate catalyst.

[0040] In a specific embodiment, the second liquid includes deionized water and / or pure water with high purity.

[0041] When the preparation method of the potassium iridate catalyst of the present invention is used, the potassium iridate sample can exhibit lower charge transfer resistance, lower overpotential and higher oxygen evolution reaction durability in an acidic medium.

[0042] Based on the above embodiments, Figure 2 As shown, the present invention also proposes a potassium iridate catalyst, which is prepared by the potassium iridate catalyst preparation method, is convenient, efficient, and safe.

[0043] In a specific embodiment, Figure 2 , Figure 3 As shown, the potassium iridate catalyst is a one-dimensional rod-shaped potassium iridate catalyst. From the X-ray diffraction peaks of the potassium iridate catalyst and the Umicore iridium oxide catalyst, it can be seen that the potassium iridate catalyst has an X-ray diffraction peak that is significantly different from that of the Umicore iridium oxide catalyst.

[0044] The potassium iridate catalyst prepared by the preparation method of the potassium iridate catalyst of the present invention has a high specific surface area and good oxygen evolution performance. Potassium iridate exhibits low charge transfer resistance, low overpotential and high durability of oxygen evolution reaction in an acidic medium. Some specific embodiments are listed below: Example 1 1 mmol K2IrCl6 · xH2O Dissolve in 80 ml of deionized water to generate a first solution. Add the required amount of n (K2IrCl6 · xH2O) : n (NH3 · H2O) = 1:10 of NH3 · H2O , to generate a second solution. The obtained second solution was subjected to ultrasonic reaction for 1 hour to generate a third solution. 100 mmol of KNO3 , generating a fourth solution. The obtained fourth solution was stirred and reacted at 80 degrees Celsius for 1 hour until the water was almost completely evaporated to obtain a potassium iridate precursor powder. The obtained potassium iridate precursor powder was placed in a quartz boat, heated to 450 degrees Celsius at a rate of 5 degrees Celsius per minute, and kept in air for 0.5 hours to obtain an initial catalyst. The initial catalyst obtained was filtered and washed with deionized water, and dried at 60 degrees Celsius in a vacuum oven to obtain a potassium iridate catalyst.

[0045] Example 2 Dissolve 1 mmol K2IrCl6·xH2O in 80 ml deionized water to generate a first solution. Add the required amount of NH3·H2O with n (K2IrCl6·xH2O): n (NH3·H2O) = 1:50 to the first solution to generate a second solution. Ultrasonicate the second solution for 1.5 hours to generate a third solution. Add 100 mmol NaNO3 to the third solution to generate a fourth solution. Stir the fourth solution at 80 degrees Celsius for 1 hour until the water is almost completely evaporated to obtain a potassium iridate precursor powder. Place the obtained potassium iridate precursor powder in a quartz boat, heat it to 500 degrees Celsius at a rate of 5 degrees Celsius per minute, and keep it in air for 0.5 hours to obtain an initial catalyst. Filter and wash the initial catalyst with deionized water, and dry it at 60 degrees Celsius in a vacuum oven to obtain a potassium iridate catalyst.

[0046] Example 3 1 mmol K2IrCl6 · xH2O Dissolve in 80 ml of deionized water to generate a first solution. Add the required amount of n (K2IrCl6 · xH2O) : n (NH3 · H2O) = 1:100 of NH3 · H2O , to generate a second solution. The obtained second solution was subjected to ultrasonic reaction for 1.5 hours to generate a third solution. 100 mmol of KNO3 , generating a fourth solution. The obtained fourth solution was stirred and reacted at 80 degrees Celsius for 1 hour until the water was almost completely evaporated to obtain a potassium iridate precursor powder. The obtained potassium iridate precursor powder was placed in a quartz porcelain boat, heated to 450 degrees Celsius at a rate of 10 degrees Celsius per minute, and kept in air for 0.5 hours to obtain an initial catalyst. The initial catalyst obtained was filtered and washed with deionized water, and dried at 60 degrees Celsius in a vacuum oven to obtain a potassium iridate catalyst.

[0047] Example 4 1 mmol H2IrCl6 · xH2O Dissolve in 100 ml of deionized water to generate a first solution. Add the required amount of n (H2IrCl6 · xH2O) : n (NH3 · H2O)= 1:100 of NH3 · H2O , to generate a second solution. The obtained second solution was subjected to ultrasonic reaction for 1.5 hours to generate a third solution. 110 mmol of KNO3 , generating a fourth solution. The obtained fourth solution is stirred and reacted at 90 degrees Celsius for 1 hour until the water is almost completely evaporated to obtain a potassium iridate precursor powder. The obtained potassium iridate precursor powder is placed in a quartz porcelain boat, heated to 500 degrees Celsius at a rate of 5 degrees Celsius per minute, and kept in air for 0.5 hours to obtain an initial catalyst. The initial catalyst obtained is filtered and washed with deionized water, and dried at 60 degrees Celsius in a vacuum oven to obtain a potassium iridate catalyst.

[0048] Example 5 1 mmol K2IrCl6 · xH2O Dissolve in 80 ml of deionized water to generate a first solution. Add the required amount of n (K2IrCl6 · xH2O) : n (NH3 · H2O)= 1:100 of NH3 · H2O, to generate a second solution. The obtained second solution was subjected to ultrasonic reaction for 1.5 hours to generate a third solution. 100 mmol of NaNO3 , generating a fourth solution. The obtained fourth solution was stirred and reacted at 80 degrees Celsius for 1 hour until the water was almost completely evaporated to obtain a potassium iridate precursor powder. The obtained potassium iridate precursor powder was placed in a quartz boat, heated to 450 degrees Celsius at a rate of 5 degrees Celsius per minute, and kept in air for 0.5 hours to obtain an initial catalyst. The initial catalyst obtained was filtered and washed with deionized water, and dried at 60 degrees Celsius in a vacuum oven to obtain a potassium iridate catalyst.

[0049] Example 6 1 mmol K2IrCl6 · xH2O Dissolve in 80 ml of deionized water to generate a first solution. Add the required amount of n (K2IrCl6 · xH2O) : n (NH3 · H2O) = 1:100 of NH4NO3 , to generate a second solution. The obtained second solution was subjected to ultrasonic reaction for 1.5 hours to generate a third solution. 100 mmol of LiNO3 , generating a fourth solution. The obtained fourth solution is stirred and reacted at 80 degrees Celsius for 1 hour until the water is almost completely evaporated to obtain a potassium iridate precursor powder. The obtained potassium iridate precursor powder is placed in a quartz porcelain boat, heated to 500 degrees Celsius at a rate of 5 degrees Celsius per minute, and kept in air for 0.5 hours to obtain an initial catalyst. The initial catalyst obtained is filtered and washed with deionized water, and dried at 60 degrees Celsius in a vacuum oven to obtain a potassium iridate catalyst.

[0050] Example 7 At 0.5 mol H2SO4 In the electrolyte, the water bath is heated to stabilize the electrolyte temperature at 25 degrees Celsius. A typical three-electrode system (Pt / C (platinum carbon catalyst) material is used as the working electrode, and the electrode area is 0.2 cm2 (0.2 per square centimeter), that is, the current density is 10 mA cm −2 (milliamperes per square centimeter) corresponds to a current of 0.002 A (ampere) and a current density of 100 mA cm −2 The corresponding current is 0.02 A (ampere), Ag / AgCl (silver-silver chloride catalyst) material is used as the reference electrode, and Pt (platinum) mesh is used as the counter electrode). The linear polarization curves of the Umicore iridium oxide catalyst and the iridium dioxide oxide catalyst prepared by the present invention are tested (such as Figure 4 As shown in the figure), when the current density is 10 mA cm −2When the current density is 10 mA cm-1, the corresponding potentials of the iridium dioxide oxide catalyst and the Umicore iridium oxide catalyst prepared by the present invention are 1.469 V (volts) and 1.539 V, respectively, which are converted into overpotentials of 239 mV (millivolts) and 309 mV (millivolts), respectively. As shown in Table 1 below, the overpotentials required for the potassium iridate catalyst and the Umicore iridium oxide catalyst prepared by the present invention for different current densities. And when the current density is 10 mA cm-1, the overpotentials required for the potassium iridate catalyst and the Umicore iridium oxide catalyst prepared by the present invention are 1.469 V (volts) and 1.539 V, respectively, which are converted into overpotentials of 239 mV (millivolts) and 309 mV, respectively. −2 When , the overpotential of the iridium dioxide oxide catalyst prepared by the present invention is 70 mV (millivolts) lower than the overpotential of the Umicore iridium oxide catalyst.

[0051] Table 1: Overpotentials required for different catalysts at different current densities

[0052] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a potassium iridate catalyst, characterized in that: The steps include: dissolving an iridium source material in a first liquid to generate a first solution; adding a chelating agent to the first solution to generate a second solution; subjecting the second solution to ultrasonic and / or stirring reaction for a certain period of time to generate a third solution; Adding a co-oxidant to the third solution to generate a fourth solution, and stirring the fourth solution at a specific temperature for a certain period of time to evaporate water, thereby obtaining a potassium iridate precursor powder; calcining and oxidizing the potassium iridate precursor powder to obtain an initial catalyst; The initial catalyst is filtered and washed, and then heated and dried to obtain a potassium iridate catalyst.

2. The method for preparing a potassium iridate catalyst according to claim 1, wherein The iridium source material includes any one of K2IrCl6, H2IrCl6, IrCl3, IrCl4, IrO2, K3IrCl6 or a mixture of at least two of the materials.

3. The method for preparing a potassium iridate catalyst according to claim 2, wherein: The chelating agent includes an amino organic compound.

4. The method for preparing a potassium iridate catalyst according to claim 3, wherein: The chelating agents include cysteamine.

5. The method for preparing a potassium iridate catalyst according to claim 1, wherein The co-oxidant comprises a metal nitrate; the metal nitrate is a single metal nitrate or a mixture of at least two metal nitrates, and the metal contained in the metal nitrate is one of K, Na, Li and Cu.

6. The method for preparing a potassium iridate catalyst according to claim 5, wherein: The first liquid includes deionized water and / or pure water; the second liquid includes deionized water and / or pure water.

7. The method for preparing a potassium iridate catalyst according to claim 1, wherein The molar ratio of the iridium source material, the chelating agent and the oxidant is 1:(1-3000):(1-1200).

8. The method for preparing a potassium iridate catalyst according to claim 1, wherein The step of calcining and oxidizing the potassium iridate precursor powder to obtain the initial catalyst includes: placing the potassium iridate precursor powder in a specific container, heating it to 300 to 800 degrees Celsius at a rate of 1 to 10 degrees Celsius per minute, and keeping it in air for 0.5 to 5 hours to obtain the initial catalyst.

9. The method for preparing a potassium iridate catalyst according to claim 1, wherein The step of filtering and washing the initial catalyst and heating and drying it to obtain the potassium iridate catalyst includes: filtering, washing and drying the initial catalyst with a second liquid to obtain the potassium iridate catalyst.

10. A potassium iridate catalyst, characterized in that The method is prepared according to any one of claims 1 to 9.

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