Ir nano-particle catalyst with rich grain boundary as well as preparation method and application of Ir nano-particle catalyst

Abstract

The invention relates to an Ir nanoparticle catalyst with rich grain boundaries and a preparation method and application thereof, and belongs to the technical field of electrode material preparation. The gram-level preparation method of the Ir nanoparticle catalyst with the rich grain boundary comprises the following steps: dissolving iridium metal salt and potassium bromide in a mixed solvent, carrying out ultrasonic treatment to uniformly disperse the iridium metal salt and the potassium bromide, and drying to obtain a precursor A; and then rapidly heating and cooling the precursor A in a Joule heating instrument to obtain the Ir nanoparticle catalyst with abundant grain boundaries. According to the preparation method disclosed by the invention, gram-level preparation of the rich-grain-boundary Ir nanoparticle catalyst can be simply realized, the prepared catalyst shows excellent electrochemical performance in an acidic oxygen evolution reaction, and a new research scheme is provided for industrial application of electrolyzed water.

Description

Technical Field

[0001] The present application relates to the technical field of electrode material preparation, and in particular to an Ir nanoparticle catalyst with abundant grain boundaries, a preparation method thereof, and an application thereof. Background Art

[0002] Oxygen evolution reaction (OER) is a key step in the process of hydrogen production by electrolysis of water. However, since the oxygen evolution reaction involves the transfer process of four electrons and four protons, it is necessary to consume a large amount of energy to overcome its reaction kinetic energy barrier. Therefore, it is particularly important to develop a catalyst with the ability of rapid electron transfer. For example, the Chinese patent with publication number CN 118595434 A discloses a microwave reduction preparation method of a nano-iridium black catalyst and its application, which uses a reducing agent as a solvent and then quickly reduces the Ir black particles with an average particle size of 1.3 nm obtained by a microwave heating method, thereby achieving uniform dispersion of the catalyst and solving the problem of particle agglomeration. However, the above method requires the use of a variety of reducing agents and the need to regulate the pH value of the solution, and the process is complicated and needs further improvement.

[0003] Constructing grain boundaries is an effective strategy for the design of Ir-based catalysts, significantly improving catalytic activity, selectivity, and stability by manipulating atomic arrangement, electronic structure, and mass transfer pathways. However, currently reported methods for constructing catalyst grain boundaries have mostly used high-temperature molten salt methods. While this method is effective for constructing grain boundaries, it requires the addition of solvent at high temperatures and the rapid cooling of the solvent, which poses safety risks during operation. Summary of the Invention

[0004] In view of this, the present application provides an Ir nanoparticle catalyst with abundant grain boundaries, a preparation method and application thereof, and adopts a strategy combining salt-assisted recrystallization and Joule heating to prepare an Ir nanoparticle catalyst with abundant grain boundaries. This preparation method has certain application prospects for electrocatalysis and has important research significance for promoting the industrialization process of iridium-based catalysts in water electrolysis, and can effectively overcome the defects of the above-mentioned existing technologies.

[0005] In a first aspect, the present application provides a gram-scale preparation method of an Ir nanoparticle catalyst having abundant grain boundaries, comprising the following steps:

[0006] Iridium metal salt and potassium bromide are dissolved in a mixed solvent, uniformly dispersed by ultrasonication, and dried to obtain a precursor A; the precursor A is then rapidly heated and cooled in a Joule heating apparatus to obtain an Ir nanoparticle catalyst with abundant grain boundaries.

[0007] The Joule heating strategy used in this application can effectively avoid safety hazards during operation. This is because the Joule heating instrument does not require the addition of additional solvents other than the added precursors during sample preparation, and the entire heating process is carried out inside the instrument, preventing close contact, thus greatly reducing safety hazards. Therefore, the use of Joule heating to achieve the rapid and safe construction of catalyst grain boundaries and the gram-scale preparation of catalysts is of great significance.

[0008] Preferably, the heating time is 60-240s, the power is 100-300W, and the voltage is 10-40V.

[0009] Preferably, the cooling time is 2-5 minutes.

[0010] Preferably, the iridium metal salt is selected from at least one of iridium trichloride, chloroiridic acid, and iridium acetylacetonate.

[0011] Preferably, the mixed solvent is a mixed solution of ethanol and ultrapure water, and the volume ratio of ethanol to ultrapure water is (4-8):1.

[0012] Preferably, the ultrasonic time is 10-60 min.

[0013] Preferably, the drying temperature is 60-120° C., and the drying time is 3-10 hours.

[0014] Preferably, the usage ratio of the iridium metal salt, potassium bromide and mixed solvent is 0.06 mM:2.5 mM:60 mL.

[0015] The second aspect of the present application further provides an Ir nanoparticle catalyst with abundant grain boundaries, which is prepared by the above-mentioned method.

[0016] The third aspect of the present application further provides a use of the above-mentioned Ir nanoparticle catalyst with abundant grain boundaries in anode electrocatalytic oxygen evolution.

[0017] Compared with the prior art, this application has the following beneficial effects:

[0018] The present application provides a gram-scale preparation method for Ir nanoparticle catalysts with abundant grain boundaries. This method can simply realize the construction of grain boundaries and can also realize the gram-scale preparation of catalysts. It is a universal preparation method for nanoparticle electrode materials. The preparation method is simple in process and easy to operate. The prepared catalyst is evenly dispersed and has good electrochemical activity and high stability. It can also exhibit relatively excellent electrochemical performance in the electrolysis of water OER reaction, providing a new research plan for the industrial application of electrolysis of water. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following briefly introduces the drawings required for use in the description of the present application or the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 This is the XRD pattern of the Ir nanoparticle catalyst with abundant grain boundaries (GB-Ir NPs) prepared in Example 1;

[0021] Figure 2 TEM image of the Ir nanoparticle catalyst (GB-Ir NPs) with abundant grain boundaries prepared in Example 1;

[0022] Figure 3 This is the OER polarization curve of the Ir nanoparticle catalyst with abundant grain boundaries (GB-Ir NPs) prepared in Example 1 in 0.5MH2SO4;

[0023] Figure 4 This is the polarization curve of the Ir nanoparticle catalyst with abundant grain boundaries (GB-Ir NPs) prepared in Example 1 in a proton exchange membrane electrolyzer;

[0024] Figure 5 This is a photo of the Ir nanoparticle catalyst (GB-Ir NPs) with abundant grain boundaries prepared in Example 1;

[0025] Figure 6 This is a stability diagram of the Ir nanoparticle catalyst with abundant grain boundaries (GB-Ir NPs) prepared in Example 1;

[0026] Figure 7 This is the TEM image of the comparative sample IrO2 nanoparticle catalyst (IrO2NPs) in Comparative Example 1. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0028] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0029] In the following examples, unless otherwise specified, all raw materials can be purchased commercially or prepared by conventional methods.

[0030] Example 1

[0031] The gram-scale preparation method of Ir nanoparticle catalysts with abundant grain boundaries (GB-Ir NPs) in this embodiment includes the following steps:

[0032] (1) Preparation of Precursor A: Iridium acetylacetonate (0.06 mM) and potassium bromide (2.5 mM) were placed in a beaker containing 50 mL of ethanol and 10 mL of ultrapure water, and ultrasonicated for 40 min to disperse them uniformly. The mixture was then kept in an oven at 80°C for 6 h and cooled to obtain Precursor A.

[0033] (2) Preparation of Ir nanoparticle catalysts with abundant grain boundaries: Precursor A was placed in a Joule heating apparatus for rapid heating and cooling. The heating time was set to 120 s, the cooling time was set to 3 min, the power was set to 200 W, and the voltage was set to 20 V. GB-Ir NPs were obtained after the treatment.

[0034] Comparative Example 1

[0035] The preparation method of the IrO2 NPs catalyst provided in this comparative example comprises the following steps:

[0036] (1) Preparation of Precursor A: Iridium acetylacetonate (0.06 mM) and potassium bromide (2.5 mM) were placed in a beaker containing 50 mL of ethanol and 10 mL of ultrapure water, and ultrasonicated for 40 min to disperse them uniformly. The mixture was then kept in an oven at 80°C for 6 h and cooled to obtain Precursor A.

[0037] (2) Preparation of IrO2 NPs: Precursor A was placed in a muffle furnace for calcination at 500°C for 2 h at a heating rate of 10°C / min, and then cooled to room temperature to obtain IrO2 NPs.

[0038] Comparative Example 2

[0039] In this comparative example, IrO2 is a commercial iridium oxide catalyst purchased from Macklin, with a CAS number of 12030-49-8 and an Ir content of greater than 84.5%.

[0040] Comparative Example 3

[0041] The commercial Pt / C catalyst in this comparative example was purchased from Johnson Matthey, model number is Hispec4000, and the platinum content is 40%.

[0042] Test Case

[0043] The structure and electrochemical performance of the Ir nanoparticle catalyst with abundant grain boundaries of Example 1 are as follows:

[0044] (A) Structural morphology and elemental characterization of the catalyst

[0045] X-ray diffraction was used to characterize the elemental composition of Ir nanoparticle catalysts with abundant grain boundaries ( Figure 1 ).from Figure 1 It can be seen that the material prepared in Example 1 corresponds to the standard card, further confirming that the catalyst is GB-IrNPs.

[0046] Field emission transmission electron microscopy (TEM) was used to observe the morphology of Ir nanoparticle catalysts with abundant grain boundaries ( Figure 2 ), these nanosheets are composed of a large number of interconnected nanoparticles with an average size of nearly 4.5nm, and the crystal faces are very rich in the nanoparticles, which is conducive to accelerating electron transport and improving the performance of the catalyst.

[0047] (B) Anode oxygen evolution performance test

[0048] A linear scan test was performed using a three-electrode system in oxygen-saturated 0.5 M H2SO4 at a scan rate of 5 mV / s.

[0049] The catalyst prepared in Example 1 exhibited superior oxygen evolution performance to that of IrO2 NPs and commercial IrO2 catalysts ( Figure 3 ).

[0050] (C) Proton exchange membrane electrolyzer performance test

[0051] The performance of GB-Ir NPs was tested in an assembled proton exchange electrolyzer. Pt / C and GB-Ir NPs were spray-coated on both sides of a Nafion 115 membrane, with the Pt / C serving as the cathode and the GB-Ir NPs as the anode. This catalyst, designated GB-IrNPs||Pt / C, was prepared using the same process for a commercial IrO2||Pt / C catalyst. The test temperature was 80°C, the electrolyte was pure water, and a linear sweep rate of 5 mV / s was used.

[0052] The GB-Ir NPs||Pt / C membrane electrode assembled with the catalyst prepared in Example 1 exhibited a proton exchange membrane water electrolysis performance superior to that of the commercial IrO2||Pt / C membrane electrode ( Figure 4 ).

[0053] (D) Catalyst Gram-Scale Preparation

[0054] By scaling up the synthesis process, the gram-scale production of GB-Ir NPs catalyst was easily achieved. The gram-scale production photo of the catalyst prepared in Example 1 is shown in FIG. Figure 5 shown.

[0055] (E) Catalyst stability diagram

[0056] In a three-electrode system, GB-Ir NPs catalyst can be used in 0.5M H2SO4 at 100mA cm -2 It can run stably for more than 350 hours, showing excellent stability ( Figure 6 ).

[0057] (F) IrO2 NPs catalyst morphology

[0058] As comparative example 1, the IrO2 NPs catalyst was obtained by calcining in a muffle furnace without using a Joule heating device for rapid heating and cooling. It is worth noting that the IrO2 NPs did not show a rich grain boundary morphology ( Figure 7 ).

[0059] Unless otherwise specified, the test method for anodic oxygen evolution of the catalysts involved in the present invention is the same as the above test method.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A gram-scale preparation method of Ir nanoparticle catalysts with abundant grain boundaries, characterized in that: The following steps are involved: Iridium metal salt and potassium bromide are dissolved in a mixed solvent, uniformly dispersed by ultrasonication, and dried to obtain a precursor A; the precursor A is then rapidly heated and cooled in a Joule heating apparatus to obtain an Ir nanoparticle catalyst with abundant grain boundaries.

2. The gram-scale preparation method of the Ir nanoparticle catalyst with abundant grain boundaries according to claim 1, characterized in that: The heating time is 60-240s, the power is 100-300W, and the voltage is 10-40V.

3. The gram-scale preparation method of the Ir nanoparticle catalyst with abundant grain boundaries according to claim 1, characterized in that: The cooling time is 2-5 minutes.

4. The gram-scale preparation method of Ir nanoparticle catalyst with abundant grain boundaries according to claim 1, characterized in that: The iridium metal salt is selected from at least one of iridium trichloride, chloroiridic acid, and iridium acetylacetonate.

5. The gram-scale preparation method of Ir nanoparticle catalyst with abundant grain boundaries according to claim 1, characterized in that: The mixed solvent is a mixed solution of ethanol and ultrapure water, and the volume ratio of ethanol to ultrapure water is (4-8):

1.

6. The gram-scale preparation method of Ir nanoparticle catalyst with abundant grain boundaries according to claim 1, characterized in that: The ultrasonic time is 10-60 min.

7. The gram-scale preparation method of Ir nanoparticle catalyst with abundant grain boundaries according to claim 1, characterized in that: The drying temperature is 60-120° C., and the drying time is 3-10 hours.

8. The gram-scale preparation method of Ir nanoparticle catalyst with abundant grain boundaries according to claim 1, characterized in that: The usage ratio of the iridium metal salt, potassium bromide and mixed solvent is 0.06 mM:2.5 mM:60 mL.

9. An Ir nanoparticle catalyst with abundant grain boundaries, characterized in that: An Ir nanoparticle catalyst with abundant grain boundaries prepared by the method according to any one of claims 1 to 8.

10. Use of the Ir nanoparticle catalyst with abundant grain boundaries according to claim 9 in anode electrocatalytic oxygen evolution.

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