Preparation method and application of supported iridium-based catalyst with oxygen overflow effect

Abstract

The invention discloses a preparation method and application of a supported iridium-based catalyst with an oxygen overflow effect, and belongs to the technical field of preparation of electrochemical catalysts. Iridium metal salt and indium tin oxide are used as raw materials, the precursor is obtained through oil bath centrifugation and then calcined, the supported iridium-based catalyst with the oxygen overflow effect is obtained, and construction of the supported iridium-based catalyst with the oxygen overflow effect can be achieved through simple operation. The catalyst shows excellent electrochemical performance in acidic oxygen evolution reaction, and a new research scheme is provided for industrial application of electrolyzed water.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical catalyst preparation, and in particular to a preparation method and application of a supported iridium-based catalyst with oxygen overflow effect. Background Art

[0002] Driven by the global energy transition and carbon neutrality goals, hydrogen production by water electrolysis has shown great potential as a sustainable clean energy production technology. Among them, the oxygen evolution reaction (OER), as the anodic half-reaction of water electrolysis, has become a key bottleneck restricting the efficiency of water electrolysis because it involves a four-electron transfer process and has sluggish kinetics. At present, iridium (Ir)-based materials are regarded as one of the most promising catalysts under acidic conditions due to their excellent OER catalytic activity and stability. However, as a scarce precious metal, iridium is expensive and has low natural abundance. Reducing the iridium loading is crucial for the large-scale implementation of proton exchange membrane water electrolysis, and its catalytic efficiency and stability still need to be further improved. At the same time, the development of simple and efficient preparation methods is also of great significance.

[0003] Existing iridium-based catalysts have the following shortcomings: Because rutile IrO2 follows an adsorption evolution mechanism, the linear scaling relationship between OOH and OH intermediates is limited by an inherent energy barrier of 0.37V, resulting in strong covalency and poor catalytic activity. Although the lattice oxygen oxidation mechanism can directly form the OO intermediate, breaking the linear relationship of OOH, the participation of lattice oxygen in the reaction produces soluble high-valent metal oxides, leading to the collapse of the catalyst structure and reduced stability.

[0004] Based on the above problems, a supported iridium-based catalyst with oxygen overflow effect was proposed for application in the oxygen evolution reaction (OER). Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of a supported iridium-based catalyst with oxygen overflow effect, so as to solve the problems in the background technology.

[0006] To achieve the above object, the present invention provides a supported iridium-based catalyst with oxygen overflow effect, comprising the following steps:

[0007] S1. Dissolving iridium metal salt and indium tin oxide in ethylene glycol, performing ultrasonic dispersion, and then transferring to an oil bath for reaction, and centrifuging to obtain a precursor;

[0008] S2. calcining the precursor in air to obtain a supported iridium-based catalyst with oxygen overflow effect.

[0009] Preferably, in S1, the mass ratio of iridium metal salt to indium tin oxide is 1:2 to 1:10.

[0010] Preferably, in S1, the iridium metal salt includes one of iridium trichloride, iridium chlorohydrate, and iridium acetylacetonate, and may also be other iridium metal salts.

[0011] Preferably, in S1, the mass of indium tin oxide is 50-150 mg, and the volume of ethylene glycol is 10-60 mL.

[0012] Preferably, in S1, the ultrasonic time is 10 to 60 minutes, the oil bath temperature is 100 to 200° C., and the oil bath time is 1 to 6 hours.

[0013] Preferably, in S2, the calcination temperature is 300-700° C., and the calcination time is 1-5 hours.

[0014] The present invention also provides a supported iridium-based catalyst with oxygen overflow effect, and the supported iridium-based catalyst is prepared by the above preparation method.

[0015] The present invention also provides an application of a supported iridium-based catalyst with oxygen overflow effect, and the prepared supported iridium-based catalyst is applied to the electrolysis of water OER reaction.

[0016] Preferably, the principle of using supported iridium-based catalysts in the OER reaction of water electrolysis is:

[0017] Oxygen overflow refers to the generation of reactive oxygen species (such as atomic oxygen O) on active sites. * During the OER reaction, the IrO2 surface is oxidized to form highly reactive oxygen intermediates (such as O * ) becomes the key species of overflow; "oxygen acceptor sites" are formed on the ITO surface, providing a low-energy barrier path to adsorb oxygen species from IrO2; the oxygen species migrated to ITO can further react, directly participate in OO coupling to generate O2, and can stabilize the reaction intermediates to avoid their excessive accumulation on the IrO2 surface and cause blockage of active sites; overflow reduces the oxygen coverage of the IrO2 surface, making more Ir sites available for water molecule adsorption and initial oxidation steps.

[0018] Therefore, the preparation method and application of a supported iridium-based catalyst with oxygen overflow effect of the present invention have the following beneficial effects:

[0019] (1) The present invention prepares a precursor by combining ultrasonic dispersion with oil bath reaction, and then obtains the target catalyst by air calcination. The operation steps are few, the conditions are mild and easy to control, which is suitable for industrial scale-up production and reduces the preparation cost. The oxygen overflow effect is used to make the oxygen intermediates adsorbed on the iridium metal site overflow to the inert carrier, thereby stabilizing the catalyst structure and synergistically enhancing the activity and stability. The prepared catalyst is suitable for water electrolysis and can exhibit relatively excellent electrochemical performance in the OER reaction of water electrolysis, providing a new research plan for the industrial application of water electrolysis.

[0020] (2) In the present invention, there is a strong interaction between the indium tin oxide carrier and the iridium active component, which can induce a significant oxygen overflow effect, accelerate the migration and conversion of oxygen species in the OER reaction, effectively improve the reaction kinetics rate, and greatly improve the catalytic activity; and indium tin oxide can optimize the electronic structure of iridium through electronic regulation, enhance its adsorption capacity for reaction intermediates, and synergistically improve the overall catalytic performance with the oxygen overflow effect.

[0021] (3) In the preparation steps of the present invention, the ultrasonic dispersion process promotes the uniform distribution of iridium metal salt on the surface of the carrier, and combined with the controllable growth of the oil bath reaction, the iridium active component is highly dispersed, which significantly improves the atomic utilization rate of the precious metal and reduces the material cost per unit activity; the calcination process enables the iridium active component to form a stable chemical bond with the carrier, inhibits the agglomeration and loss of the active component, and can maintain high catalytic performance in the long-term water electrolysis OER reaction, thereby extending the service life of the catalyst.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the XRD pattern of IrO2 / ITO in Example 1 of the present invention;

[0024] Figure 2 TEM image of IrO2 / ITO in Example 1 of the present invention;

[0025] Figure 3 1 is a comparison diagram of the OER polarization curves of Application Example 1 and Comparative Example 1 of the present invention;

[0026] Figure 4 This is a comparison diagram of polarization curves of Application Example 1 and Comparative Example 1 of the present invention in a proton exchange membrane electrolyzer;

[0027] Figure 5 These are XPS graphs of Application Example 1 and Comparative Example 1 of the present invention after the reaction, wherein a represents IrO2 / ITO and b represents IrO2. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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.

[0030] Example 1

[0031] This example prepares a supported iridium-based catalyst with oxygen overflow effect: IrO2 / ITO, and the specific steps are as follows:

[0032] S1. Iridium trichloride (0.13 mM) and indium tin oxide (0.1 g) were placed in a beaker containing 20 mL of ethylene glycol, and then ultrasonicated for 30 min. After uniform dispersion, the mixture was transferred to an oil bath and heated at 140 ° C for 3 h. The precursor A was obtained by centrifugation.

[0033] S2. Place the precursor A in a muffle furnace, set the temperature to 300°C, and keep it warm for 3 hours. After completion, cool it to room temperature to obtain IrO2 / ITO.

[0034] The IrO2 / ITO catalyst prepared in Example 1 was characterized by X-ray diffraction, and its elemental composition information is as follows: Figure 1 As shown, it can be seen that the material prepared in Example 1 corresponds to the standard card, further confirming that the catalyst is IrO2 / ITO.

[0035] like Figure 2 As shown, the morphology of the supported iridium-based catalyst with oxygen overflow effect can be seen using field emission transmission electron microscopy.

[0036] Example 2

[0037] This example prepares a supported iridium-based catalyst with oxygen overflow effect: IrO2 / ITO, and the specific steps are as follows:

[0038] S1. Iridium trichloride (0.03 mM) and indium tin oxide (0.1 g) were placed in a beaker containing 60 mL of ethylene glycol, and then ultrasonicated for 60 min. After uniform dispersion, the mixture was transferred to an oil bath and heated at 200 ° C for 6 h. The precursor A was obtained by centrifugation.

[0039] S2. Place the precursor A in a muffle furnace, set the temperature to 500°C, and keep it warm for 5 hours. After completion, cool it to room temperature to obtain IrO2 / ITO.

[0040] Example 3

[0041] This example prepares a supported iridium-based catalyst with oxygen overflow effect: IrO2 / ITO, and the specific steps are as follows:

[0042] S1. Iridium trichloride (0.16 mM) and indium tin oxide (0.1 g) were placed in a beaker containing 20 mL of ethylene glycol, ultrasonicated for 30 min, then transferred to an oil bath, the reaction temperature was 140 ° C, the insulation time was 3 h, and centrifuged to obtain precursor A.

[0043] S2. Precursor A is placed in a muffle furnace, the temperature is set to 300°C, the holding time is 3 hours, and IrO2 / ITO is obtained after cooling to room temperature.

[0044] Example 4

[0045] This example prepares a supported iridium-based catalyst with oxygen overflow effect: IrO2 / ITO, and the specific steps are as follows:

[0046] S1. Iridium trichloride (0.13 mM) and indium tin oxide (0.1 g) were placed in a beaker containing 10 mL of ethylene glycol, ultrasonicated for 30 min, then transferred to an oil bath, the reaction temperature was 110°C, the insulation time was 3 h, and centrifuged to obtain precursor A.

[0047] S2. Precursor A is placed in a muffle furnace, the temperature is set to 300°C, the holding time is 3 hours, and IrO2 / ITO is obtained after cooling to room temperature.

[0048] Application Example 1

[0049] The IrO2 / ITO catalyst prepared in Example 1 was used as a raw material to perform an anodic oxygen evolution performance test and a proton exchange membrane electrolyzer performance test. The specific conditions for the anodic oxygen evolution performance test were as follows: a linear scan test was performed using a three-electrode system in oxygen-saturated 0.5M H2SO4 at a scan rate of 5mV / s.

[0050] The specific conditions for the proton exchange membrane electrolyzer performance test are as follows: the performance test of IrO2 / ITO is carried out in an assembled proton exchange electrolyzer, the electrolyte is pure water, and a linear scan test is carried out at a scan rate of 5mV / s.

[0051] Comparative Application Example 1

[0052] This comparative example uses a commercial IrO2 catalyst purchased from Macklin, with a CAS number of 12030-49-8 and an Ir content greater than 84.5%, to conduct an anode oxygen evolution performance test and a proton exchange membrane electrolyzer performance test.

[0053] Figure 3This is a comparison chart of the anode oxygen evolution performance test of Example 1 and Comparative Example 1. The results show that the IrO2 / ITO catalyst prepared in Example 1 is superior to the IrO2 catalyst in oxygen evolution performance.

[0054] Figure 4 The performance comparison results of the proton exchange membrane electrolyzer using Example 1 and Comparative Example 1 are shown. The comparison shows that the catalyst prepared in Example 1 exhibits oxygen evolution performance that is superior to that of the IrO2 catalyst.

[0055] XPS comparison of IrO2 / ITO and commercial IrO2 catalysts after OER reaction, such as Figure 5 As shown in the figure, after 5000 cycles of CV, the Ir 4f shifted by 0.32 eV to higher binding energies in commercial IrO2, indicating that Ir was oxidized to a higher valence state, resulting in decreased activity. In contrast, the shift in IrO2 / ITO was only 0.17 eV, indicating a relatively stable valence state, further verifying the protective effect of the oxygen overflow strategy on the loaded IrO2.

[0056] Through the above performance comparison, the method protected by the present invention utilizes the oxygen overflow effect to allow the oxygen intermediates adsorbed on the iridium metal site to overflow onto the inert carrier, thereby stabilizing the catalyst structure and synergistically enhancing the electrochemical activity and stability, so that it can exhibit relatively excellent electrochemical performance in the water electrolysis OER reaction.

[0057] Therefore, the present invention provides a preparation method and application of a supported iridium-based catalyst with an oxygen overflow effect. Iridium metal salt and indium tin oxide are used as raw materials, a precursor is obtained by oil bath centrifugation, and then calcined to obtain a supported iridium-based catalyst with an oxygen overflow effect. The supported iridium-based catalyst with an oxygen overflow effect can be constructed through simple operations. The catalyst exhibits excellent electrochemical performance in an acidic oxygen evolution reaction, providing a new research solution for the industrial application of water electrolysis.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a supported iridium-based catalyst having an oxygen overflow effect, characterized in that: The following steps are involved: S1. Dissolving iridium metal salt and indium tin oxide in ethylene glycol, performing ultrasonic dispersion, and then transferring to an oil bath for reaction, and centrifuging to obtain a precursor; S2. calcining the precursor in air to obtain a supported iridium-based catalyst with oxygen overflow effect.

2. The method for preparing a supported iridium-based catalyst having an oxygen overflow effect according to claim 1, wherein: In the above-mentioned S1, the mass ratio of iridium metal salt to indium tin oxide is 1:2 to 1:

10.

3. The method for preparing a supported iridium-based catalyst having an oxygen overflow effect according to claim 1, wherein: In S1, the iridium metal salt includes one of iridium trichloride, chloroiridic acid, and iridium acetylacetonate.

4. The method for preparing a supported iridium-based catalyst having an oxygen overflow effect according to claim 1, wherein: In the above-mentioned S1, the mass of indium tin oxide is 50-150 mg, and the volume of ethylene glycol is 10-60 mL.

5. The method for preparing a supported iridium-based catalyst having an oxygen overflow effect according to claim 1, wherein: In the S1, the ultrasonic time is 10 to 60 minutes, the oil bath temperature is 100 to 200° C., and the oil bath time is 1 to 6 hours.

6. The method for preparing a supported iridium-based catalyst having an oxygen overflow effect according to claim 1, wherein: In the above S2, the calcination temperature is 300-700° C., and the calcination time is 1-5 hours.

7. A supported iridium-based catalyst having an oxygen overflow effect, characterized in that: The supported iridium-based catalyst is prepared by the preparation method described in any one of claims 1 to 6.

8. An application of a supported iridium-based catalyst having an oxygen overflow effect, characterized in that: The supported iridium-based catalyst prepared in claim 7 is applied to the water electrolysis OER reaction.

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