Preparation method and application of rutile type iridium oxide catalyst

Abstract

The invention provides a preparation method of a rutile type iridium oxide catalyst, which comprises the following steps: S1, mixing potassium hydroxide and water to form a potassium hydroxide solution, and mixing an iridium precursor and water to form an iridium precursor solution; s2, dropwise adding the iridium precursor solution into a potassium hydroxide solution to obtain a mixed solution, and evaporating the mixed solution to dryness to obtain a mixture; and S3, mixing the mixture with a strong oxidant, calcining, and finally washing and drying to obtain the rutile type iridium oxide catalyst. According to the preparation method of the rutile type iridium oxide catalyst, the strong oxidant is added to reduce the calcination temperature to synthesize the rutile type IrO2 catalyst, so that the OER activity and stability of the rutile type IrO2 catalyst are remarkably improved, the problem of insufficient activity of IrO2 electrolyzed water is effectively solved, and the overall efficiency of PEM electrolyzed water is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of hydrogen production by water electrolysis through a proton exchange membrane, in particular to a preparation method of a rutile-type iridium oxide catalyst and application thereof. BACKGROUND

[0002] The hydrogen production by water electrolysis through a proton exchange membrane takes solid as an electrolyte and pure water as raw material, and under the action of direct current, hydrogen is generated at the cathode and oxygen is generated at the anode. The technology is concerned due to the advantages of no pollution, small occupation, high efficiency, good compatibility with renewable energy and high safety.

[0003] The core components of a PEM electrolytic cell include a bipolar plate, a porous transport layer and a membrane electrode, wherein the membrane electrode is composed of a cathode / anode catalyst layer, a proton exchange membrane and a sealing layer; at present, the anode catalyst of a commercial PEM electrolytic cell generally adopts a noble metal iridium oxide (IrO2), however, the IrO2 is high in cost and accounts for a large proportion of the cost of a single cell, which becomes one of the bottlenecks restricting the commercialization of the technology; in addition, iridium is limited as a rare metal resource, and excessive use will aggravate the supply pressure, which is not conducive to sustainable development; in actual operation, the oxygen evolution reaction (OER) of IrO2 may also decay over time, resulting in a decrease in electrolysis efficiency, affecting the hydrogen production and equipment stability, therefore, improving the catalytic efficiency of IrO2 and reducing the amount of iridium are crucial to realize the goal of “reducing cost and increasing efficiency” of the hydrogen production by water electrolysis through a proton exchange membrane. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art, provide a preparation method of a rutile-type iridium oxide catalyst, improve the OER activity and stability of the iridium oxide catalyst, effectively improve the OER efficiency of the anode of water electrolysis, and reduce the amount of iridium to realize the goal of reducing cost and increasing efficiency.

[0005] The technical solution adopted by the present application is as follows: A preparation method of a rutile-type iridium oxide catalyst, comprising the following steps: Step S1. Mixing potassium hydroxide and water to form a potassium hydroxide solution, and mixing an iridium precursor and water to form an iridium precursor solution; Step S2. Dropping the iridium precursor solution into the potassium hydroxide solution to obtain a mixed solution, and evaporating the mixed solution to obtain a mixture; Step S3. Mixing the mixture with a strong oxidizing agent, then calcining, and finally washing and drying to obtain the rutile-type iridium oxide catalyst.

[0006] Preferably, the preparation method of the rutile-type iridium oxide catalyst, wherein the mass concentration of the potassium hydroxide solution in step S1 is 0.005-0.03 g / mL.

[0007] Preferably, the preparation method of the rutile-type iridium oxide catalyst, wherein the iridium precursor in step S1 is selected from one of chloroiridic acid, sodium chloroiridate, and iridium chloride, and the mass concentration of the iridium precursor is 0.01-0.03 g / mL.

[0008] Preferably, the preparation method of the rutile-type iridium oxide catalyst, wherein the mass ratio of the mixture to the strong oxidizing agent in step S3 is 3-5:0.1-0.5.

[0009] Preferably, the preparation method of the rutile-type iridium oxide catalyst, wherein the strong oxidizing agent in step S3 is selected from one or more of peroxide, potassium perchlorate, potassium permanganate, and potassium dichromate, and the peroxide is selected from one of sodium peroxide, potassium peroxide, and calcium peroxide.

[0010] Preferably, the preparation method of the rutile-type iridium oxide catalyst, wherein the calcination in step S3 is performed in an air atmosphere, the calcination temperature is 200-600℃, and the calcination time is 2-3 h.

[0011] Preferably, the preparation method of the rutile-type iridium oxide catalyst, wherein the drying temperature in step S3 is 60-100℃, and the drying time is 6-10 h.

[0012] The application of the rutile-type iridium oxide catalyst prepared by the preparation method of the rutile-type iridium oxide catalyst, wherein the rutile-type iridium oxide catalyst is applied to a proton exchange membrane water electrolysis anode catalyst.

[0013] Advantages of the present application: (1) The preparation method of the rutile-type iridium oxide catalyst of the present application significantly improves the OER activity and stability of the rutile-type IrO2 catalyst by adding a strong oxidizing agent to reduce the calcination temperature, effectively solving the problem of insufficient IrO2 water electrolysis activity, thereby improving the overall efficiency of PEM water electrolysis.

[0014] (2) The preparation method of the rutile-type iridium oxide catalyst of the present application realizes low-temperature calcination of IrO2 while still maintaining the rutile structure, which not only reduces the process difficulty of the anode catalyst, but also enhances the activity and service life of the catalyst; in terms of commercialization, this preparation process optimization is crucial for reducing the total cost of hydrogen energy production and improving PEM water electrolysis hydrogen production technology.

[0015] (3) The preparation method of the rutile-type iridium oxide catalyst of the present application, from the perspective of resources and environment, iridium is an extremely scarce noble metal resource, and after optimizing the synthesis process, the amount of IrO2 can be appropriately reduced, the rare metal resource can be significantly saved, which conforms to the sustainable development concept of efficient resource utilization, reduces environmental pollution and ecological destruction caused by iridium mining and refining process, and embodies the environmental protection benefit.

[0016] (4) The preparation method of the rutile-type iridium oxide catalyst of the present application, low-temperature calcination synthesis of rutile-type IrO2, while greatly improving the OER activity and electrolysis efficiency, realizes the effective reduction of anode noble metal iridium, has the advantages of cost reduction and resource saving, and effectively improves the catalyst activity and stability, not only reduces the amount of noble metal, but also more effectively promotes the cost competitiveness and sustainable development of PEM water electrolysis hydrogen production technology, which has important value for accelerating the commercialization application of hydrogen energy industry. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the three-electrode linear scan graph of the iridium oxide catalyst of the present application Example 1-5.

[0018] Figure 2 is the three-electrode linear scan graph of the iridium oxide catalyst of the present application Example 1 and Comparative Example 1.

[0019] Figure 3 is the XRD graph of the iridium oxide catalyst of the present application Example 2 and Comparative Example 2.

[0020] Figure 4 is the three-electrode linear scan graph of the iridium oxide catalyst of the present application Example 2 and Comparative Example 2.

[0021] Figure 5 is the three-electrode linear scan graph of the iridium oxide catalyst of the present application Example 3 and Comparative Example 3.

[0022] Figure 6 is the three-electrode linear scan graph of the iridium oxide catalyst of the present application Example 4 and Comparative Example 4.

[0023] Figure 7 is the three-electrode linear scan graph of the iridium oxide catalyst of the present application Example 5 and Comparative Example 5. DETAILED DESCRIPTION

[0024] The present application will be further described below in conjunction with specific examples.

[0025] Example 1 A preparation method of a rutile-type iridium oxide catalyst, comprising the following steps: Step S1. Mix 1 g of potassium hydroxide and 200 ml of water to form a potassium hydroxide solution, and mix 2 g of chloroiridic acid and 200 ml of water to form a chloroiridic acid solution; Step S2. Drop the chloroiridic acid solution into the potassium hydroxide solution, stir at 80°C for 3 h, and evaporate to dryness to obtain a mixture; Step S3. Mix the mixture with 0.1 g of potassium peroxide, then calcine at 350°C in air for 2 h, and finally wash and dry at 80°C for 8 h to obtain a rutile-type iridium oxide catalyst.

[0026] Example 2 A method for preparing a rutile-type iridium oxide catalyst, comprising the following steps: Step S1. Mix 2 g of potassium hydroxide and 200 ml of water to form a potassium hydroxide solution, and mix 2 g of chloroiridic acid and 200 ml of water to form a chloroiridic acid solution; Step S2. Drop the chloroiridic acid solution into the potassium hydroxide solution, stir at 80°C for 3 h, and evaporate to dryness to obtain a mixture; Step S3. Mix the mixture with 0.1 g of potassium peroxide, then calcine at 350°C in air for 2 h, and finally wash and dry at 80°C for 8 h to obtain a rutile-type iridium oxide catalyst.

[0027] Example 3 A method for preparing a rutile-type iridium oxide catalyst, comprising the following steps: Step S1. Mix 3 g of potassium hydroxide and 200 ml of water to form a potassium hydroxide solution, and mix 2 g of chloroiridic acid and 200 ml of water to form a chloroiridic acid solution; Step S2. Drop the chloroiridic acid solution into the potassium hydroxide solution, stir at 80°C for 3 h, and evaporate to dryness to obtain a mixture; Step S3. Mix the mixture with 0.1 g of potassium peroxide, then calcine at 350°C in air for 2 h, and finally wash and dry at 80°C for 8 h to obtain a rutile-type iridium oxide catalyst.

[0028] Example 4 A method for preparing a rutile-type iridium oxide catalyst, comprising the following steps: Step S1. Mix 2 g of potassium hydroxide and 200 ml of water to form a potassium hydroxide solution, and mix 2 g of chloroiridic acid and 200 ml of water to form a chloroiridic acid solution; Step S2. Drop the chloroiridic acid solution into the potassium hydroxide solution, stir at 80°C for 3 h, and evaporate to dryness to obtain a mixture; Step S3. The mixture was mixed with 0.3 g potassium peroxide, then calcined at 350℃ in air for 2 h, finally washed, dried at 80℃ for 8 h to obtain the rutile-type iridium oxide catalyst.

[0029] Example 5 A method for preparing a rutile-type iridium oxide catalyst, comprising the following steps: Step S1. 2 g of potassium hydroxide and 200 ml of water were mixed to form a potassium hydroxide solution, and 2 g of chloroiridic acid and 200 ml of water were mixed to form a chloroiridic acid solution; Step S2. The chloroiridic acid solution was added dropwise to the potassium hydroxide solution, stirred at 80℃ for 3 h and evaporated to obtain a mixture; Step S3. The mixture was mixed with 0.5 g of potassium peroxide, then calcined at 350℃ in air for 2 h, finally washed, dried at 80℃ for 8 h to obtain the rutile-type iridium oxide catalyst.

[0030] Comparative Example 1 Comparative Example 1 differs from Example 1 in that the amount of potassium hydroxide added in step S1 is 0.7 g, and the other steps are the same.

[0031] Comparative Example 2 Comparative Example 2 differs from Example 2 in that no potassium peroxide is added in step S3, and the other steps are the same.

[0032] Comparative Example 3 Comparative Example 3 differs from Example 3 in that the amount of potassium hydroxide added in step S1 is 4 g, and the other steps are the same.

[0033] Comparative Example 4 Comparative Example 4 differs from Example 4 in that the amount of potassium peroxide added in step S3 is 1 g, and the other steps are the same.

[0034] Comparative Example 5 Comparative Example 5 differs from Example 5 in that the mixture is not calcined after mixing with potassium peroxide in step S3, and the other steps are the same.

[0035] The catalysts obtained in Examples 1-5 and Comparative Examples 1-5 were characterized for physical properties and electrochemistry; electrochemical tests were performed in a three-electrode system, and the activity was mainly observed as the current density j = 10 mA cm -2 overpotential η , the specific values are shown in Table 1, η The smaller the overpotential, the higher the OER activity of the catalyst, and the more conducive to improving the efficiency of water electrolysis. Compared with other transition metals or other synthesis conditions, the IrO2 prepared by the present patent has higher OER activity and stability.

[0036] Figure 1 Three-electrode linear sweep plots of the iridium oxide catalysts of Examples 1-5, from Figure 1 It can be concluded that the OER overpotential of the iridium oxide decreases after the addition of a proper amount of strong oxidant, proving that the water electrolysis activity is improved.

[0037] Figure 2 Three-electrode linear sweep plots of the iridium oxide catalysts of Examples 1 and Comparative Example 1, from Figure 2 It can be concluded that the OER activity of the obtained iridium oxide catalyst decreases when the potassium hydroxide content decreases; from Figure 3 It can be observed from the XRD patterns of that when a proper amount of strong oxidant is added, the broad peak of the catalyst changes to the rutile structure, Figure 4 Three-electrode linear sweep plots of the iridium oxide catalysts of Examples 2 and Comparative Example 2, from Figure 4 It can be concluded that the change in the catalyst structure effectively improves the stability in the water electrolysis process, with the decay rate increasing from 14.8% to 10%.

[0038] Figure 5 Three-electrode linear sweep plots of the iridium oxide catalysts of Examples 3 and Comparative Example 3, from Figure 5 It can be concluded that the activity of the catalyst decreases when the potassium hydroxide content increases to a certain extent, so the amount of potassium hydroxide needs to be selected appropriately for the reaction, Figure 6 Three-electrode linear sweep plots of the iridium oxide catalysts of Examples 4 and Comparative Example 4, from Figure 6 It can be concluded that when the amount of strong oxidant is greatly increased under the condition of an appropriate amount of base, the activity of the catalyst decreases, and the possible reason is that the excess of strong oxidant easily affects the conductivity of the catalyst itself, causing the catalyst itself to be unable to effectively perform the OER process.

[0039] Figure 7 Three-electrode linear sweep plots of the iridium oxide catalysts of Examples 5 and Comparative Example 5, in which the amount of added strong oxidant is unchanged, and the precursor is compared before and after calcination, from Figure 7 It can be concluded that the sample of Comparative Example 1, which is not calcined, has excellent OER performance in the first test (Comparative Example 5-1), but the activity greatly decreases in the second test (Comparative Example 5-2), proving that the stability is poor without calcination, so it is not suitable for direct sample testing without calcination.

[0040] Therefore, when an appropriate amount of strong oxidant and a suitable amount of base are added, the water electrolysis activity of the iridium oxide catalyst can be effectively improved, and the stability is also improved to a certain extent. The synthesis process also has a greater impact on the activity and stability, so the synthesis needs to be performed under the specified conditions.

[0041] Table 1

[0042] Finally, it should be noted that the above detailed description is merely illustrative of the technical solutions of the present application and is not limiting, and although the present application has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application, and all should be encompassed in the scope of the claims of the present application.

Claims

1. A method for preparing a rutile iridium oxide catalyst, characterized in that: The following steps are involved: Step S1. mixing potassium hydroxide and water to form a potassium hydroxide solution, and mixing an iridium precursor and water to form an iridium precursor solution; Step S2. adding the iridium precursor solution dropwise to the potassium hydroxide solution to obtain a mixed solution, and evaporating the mixed solution to dryness to obtain a mixture; Step S3: mixing the mixture with a strong oxidant, calcining, washing, and drying to obtain a rutile iridium oxide catalyst.

2. The preparation method of rutile iridium oxide catalyst according to claim 1, wherein The mass concentration of the potassium hydroxide solution in step S1 is 0.005~0.03 g / mL.

3. The preparation method of rutile iridium oxide catalyst according to claim 1, wherein The iridium precursor in step S1 is selected from one of chloroiridic acid, sodium chloroiridate, and iridium chloride, and the mass concentration of the iridium precursor is 0.01-0.03 g / mL.

4. The preparation method of rutile iridium oxide catalyst according to claim 1, wherein In step S3, the mass ratio of the mixture to the strong oxidant is 3-5:0.1-0.

5.

5. The preparation method of rutile iridium oxide catalyst according to claim 1, wherein In step S3, the strong oxidant is selected from one or more of peroxide, potassium perchlorate, potassium permanganate, and potassium dichromate, and the peroxide is selected from one of sodium peroxide, potassium peroxide, and calcium peroxide.

6. The preparation method of rutile iridium oxide catalyst according to claim 1, wherein In step S3, the calcination is carried out in an air atmosphere, the calcination temperature is 200-600° C., and the calcination time is 2-3 h.

7. The preparation method of rutile iridium oxide catalyst according to claim 1, wherein In step S3, the drying temperature is 60-100° C., and the drying time is 6-10 h.

8. Use of a rutile iridium oxide catalyst prepared by the method for preparing a rutile iridium oxide catalyst according to any one of claims 1 to 7, characterized in that: Rutile iridium oxide catalyst is used in the anode catalyst layer of proton exchange membrane water electrolysis.

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