A proton exchange membrane water electrolysis anode material with low iridium loading and a preparation method thereof

Abstract

The application belongs to the field of proton exchange membrane (PEM) water electrolysis, and discloses a low-iridium-loading proton exchange membrane water electrolysis anode material and a preparation method thereof. The method comprises the following steps: firstly, preparing a polyoxometalate nanosheet; and then loading active metal Ir nanoparticles on the surface of the nanosheet by using a solvothermal method, so as to obtain a water electrolysis anode material. The method simultaneously realizes the improvement of catalytic activity and the reduction of the amount of noble metal, and the obtained product has low Ir loading, high activity and good stability, thereby providing more design space and possibility for the development of a new type of catalyst.

Description

Technical Field

[0001] This invention relates to a proton exchange membrane anode material for water electrolysis, belonging to the field of acidic water electrolysis technology. Background Technology

[0002] Water electrolysis was discovered by scientists Nicholson and Carlisle in 1800 and is a mature technology with over a century of history. Alkaline water electrolysis was first industrialized in 1920. While currently technologically mature and with low investment and operating costs, it suffers from problems such as alkali loss, corrosion, and high energy consumption. In contrast, proton exchange membrane (PEM) uses a perfluorosulfonic acid proton exchange membrane with good stability as the solid electrolyte to replace the asbestos membrane, effectively preventing electron transfer and improving the safety of the electrolyzer. Compared to alkaline water electrolysis, PEM water electrolysis has a higher operating current density, higher overall efficiency, and a higher hydrogen gas integral, making it a promising technology for hydrogen production through water electrolysis. The efficiency of water electrolysis is hampered by the oxygen evolution reaction (OER) at the anode, while the hydrogen evolution reaction (HER) at the cathode, a two-electron transport process, is relatively easier. However, the OER reaction, being a four-electron-proton coupling reaction, requires higher energy to overcome its slow kinetics. PEM electrolyzers typically use iridium (Ir)-based catalysts as OER catalysts, which are more stable than ruthenium under acidic conditions and have a lower overpotential than platinum. However, given its global reserves and the performance of Ir-based catalytic materials, only by reducing the current usage by about 20 times (from the current 1 mg) can the best results be achieved. Ir cm -2 Reduced to less than 0.05mg Ir cm -2 Only then can the widespread application of PEM technology be realized.

[0003] In summary, a simple and efficient preparation method is needed to synthesize nanomaterials with low iridium loading, while ensuring that the material has high activity and stability to meet its application as an Ir-based catalyst in water electrolysis. Summary of the Invention

[0004] Based on the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing a proton exchange membrane anode material with low iridium loading. The technical problem to be solved is to make the preparation method simple and highly reproducible, while making the obtained product have excellent stability and outstanding electrochemical performance.

[0005] The present invention solves the technical problem by adopting the following technical solution:

[0006] A method for preparing a low-iridium-loading proton exchange membrane anode material for water electrolysis is characterized by: firstly, preparing polyoxometalate nanosheets, and then loading active metal Ir nanoparticles onto the surface of the nanosheets using a solvothermal method to obtain the water electrolysis anode material. Specifically, the method includes the following steps:

[0007] Step 1: Add 0.16g-0.17g of phosphomolybdic acid, 10-11mL of 1-octadecene, and 6-7mL of oleylamine sequentially to 14-16mL of deionized water and stir magnetically until homogeneous to obtain mixed solution A; pour mixed solution A into a polytetrafluoroethylene-lined reactor and react at 180℃-200℃ for 10-13h; after the reaction is completed, cool to room temperature and wash with a mixed solvent of cyclohexane and ethanol by centrifugation to obtain PMA nanosheets;

[0008] Step 2: Add 0.015g-0.016g of iridium chloride to 11-12mL of isopropanol and disperse by ultrasonication. Then add 1-2mL of cyclohexane-dispersed PMA nanosheets and stir by ultrasonication and magnetic stirring to obtain mixed solution B. Pour the mixed solution B into a polytetrafluoroethylene-lined reactor and react at 110-150℃ for 6-10h. After the reaction is completed, cool to room temperature and wash with ethanol by centrifugation to obtain the Ir / PMA composite material for proton exchange membrane water electrolysis anode material.

[0009] Preferably, in steps 1 and 2, the rotation speed of the magnetic stirring is 350 to 450 rpm.

[0010] Preferably, in step 1, the centrifugation speed is 10,000 rpm.

[0011] Preferably, in step 2, the centrifugation speed is 12000 rpm.

[0012] The Ir / PMA composite material prepared by this invention can be used as an anode material for PEM water electrolysis.

[0013] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0014] 1. In this invention, PMA nanosheets are first prepared by mixing a good solvent with a poor solvent. Then, active metal Ir is loaded onto the surface of the nanosheets using a solvothermal method. By controlling the structural composition and morphology, an electrolytic water anode material Ir / PMA with low Ir loading, high activity and good stability is prepared.

[0015] 2. The product obtained by this invention has excellent stability and outstanding electrochemical performance, and can be used as a catalyst material in the oxygen evolution reaction, effectively solving the problems of high cost and poor stability of iridium-based catalysts in the oxygen evolution reaction.

[0016] 3. The preparation method of Ir / PMA material provided by the present invention has the advantages of simple operation, good repeatability and uniform product structure. Attached Figure Description

[0017] Figure 1 The image shows a transmission electron microscope (TEM) image of the PMA obtained in step 1 of Example 1.

[0018] Figure 2 The image shown is a transmission electron microscope (TEM) image of the Ir / PMA composite material obtained in step 2 of Example 1.

[0019] Figure 3 The X-ray diffraction pattern of the Ir / PMA composite material obtained in step 2 of Example 1;

[0020] Figure 4 The X-ray photoelectron spectrum of the Ir / PMA composite material obtained in step 2 of Example 1 is shown below.

[0021] Figure 5 This is a comparison chart of the electrochemical performance of the Ir / PMA composite material obtained in step 2 of Example 1 and commercial iridium black (Ir Black);

[0022] Figure 6 This is a comparison chart of the electrochemical mass activity of the Ir / PMA composite material obtained in step 2 of Example 1 and commercial iridium black (Ir Black);

[0023] Figure 7 This is a comparison of the electrochemical stability of the Ir / PMA composite material obtained in step 2 of Example 1 with commercial iridium black. Detailed Implementation

[0024] To further illustrate the features and advantages of the present invention, the embodiments of the present invention are described in detail below. The following embodiments are only a part of the present invention, and the scope of protection of the present invention is not limited to the following embodiments.

[0025] The centrifuge used in the following examples is an Anke TGL-10B manufactured by Shanghai Anting Scientific Instrument Factory, the magnetic stirrer is an MS-MS-10 multi-head magnetic stirrer manufactured by Shanghai Kunquan Biotechnology Co., Ltd., and the transmission electron microscope is a JEOL-F2010 manufactured in Japan.

[0026] Unless otherwise specified, all reagents and materials used in the following examples are commercially available. The pharmaceuticals used in the following examples were purchased and used directly without any processing.

[0027] Example 1

[0028] In this embodiment, Ir / PMA was prepared according to the following steps:

[0029] Step 1: Take 0.1604g of phosphomolybdic acid (H3Mo) 12 O 40 Add xH2O) to 16 mL of deionized water and stir magnetically for 10 min (400 rpm). Add 10 mL of 1-octadecene and stir magnetically (400 rpm) for 10 min. Finally, add 6 mL of oleylamine to obtain mixed solution A. Pour mixed solution A into a polytetrafluoroethylene-lined reactor and transfer it to an oven to react at 190 °C for 12 h. After the reaction is completed, cool to room temperature and wash with a mixed solvent of cyclohexane and ethanol (volume ratio of 1:3) by centrifugation (centrifugation speed of 10000 rpm) to obtain PMA nanosheets, which are dispersed in 1 mL of cyclohexane for later use.

[0030] Step 2: Weigh 0.0151g of iridium chloride (IrCl3), sonicate it with 12mL of isopropanol for 20min, add 1mL of cyclohexane-dispersed PMA nanosheets, sonicate for 15min, and then magnetically stir for 30min (400rpm) to obtain mixed solution B; pour mixed solution B into a polytetrafluoroethylene-lined reactor, transfer it to an oven and react at 130℃ for 6h; after the reaction is completed, cool to room temperature, and wash with ethanol by centrifugation (centrifugation speed of 10000rpm) to obtain the Ir / PMA composite material.

[0031] Figure 1 This is a transmission electron microscope (TEM) image of the PMA ultrathin nanosheets obtained in step 1 of Example 1. Figure 2 The image shows a transmission electron microscope (TEM) image of the Ir / PMA composite material obtained in step 2 of Example 1. It can be seen from the image that iridium nanoparticles are uniformly loaded on the nanosheets. Figure 3 The image shows the X-ray diffraction pattern of the Ir / PMA composite material obtained in step 2 of Example 1. Figure 4 The image shows the X-ray photoelectric spectrum of the Ir / PMA composite material obtained in step 2 of Example 1, further demonstrating that the iridium nanoparticles are loaded on the nanosheets.

[0032] Weigh 5 mg Ir / PMA, add 1 mL isopropanol and 20 μL Nafion, and sonicate for at least 30 min to ensure uniform catalyst dispersion. Then, drop 16 μL of the dispersion onto a gold electrode, controlling the catalyst loading at 84 μg Ir / cm². 2 After the dispersion was dried, it was used as the working electrode for oxygen evolution reaction (OER) testing. The reference electrode was Ag / AgCl, and the counter electrode was a carbon rod electrode. Electrochemical tests were performed in a 0.5 M H₂SO₄ electrolyte saturated with O₂. For comparison, the same tests were also performed using commercially available Ir Black with a loading of 0.4 mg Ir / cm³. 2 .

[0033] Figure 5This is a comparison of the electrochemical performance of the target product Ir / PMA obtained in Example 1 and commercial iridium black. The graph shows that the activity of Ir / PMA is significantly higher than that of commercial iridium black. Figure 6 The graph shows a comparison of the electrochemical activity of the target product Ir / PMA obtained in Example 1 with that of commercial iridium black. As can be seen from the graph, after conversion to Ir loading, the activity of Ir / PMA is significantly higher than that of commercial iridium black. Figure 7 The graph shows a comparison of the stability performance of the target product Ir / PMA obtained in Example 1 with that of commercial iridium black. It can be seen from the graph that the stability of Ir / PMA is significantly higher than that of commercial iridium black.

[0034] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a proton exchange membrane anode material for water electrolysis with low iridium loading, characterized in that: First, polyoxometalate nanosheets are prepared. Then, active metal Ir nanoparticles are loaded onto the surface of the nanosheets using a solvothermal method to obtain a water electrolysis anode material. The specific steps include the following: Step 1: Add 0.16 g to 0.17 g of phosphomolybdic acid, 10 to 11 mL of 1-octadecene, and 6 to 7 mL of oleylamine sequentially to 14-16 mL of deionized water and stir magnetically until homogeneous to obtain mixed solution A; pour mixed solution A into a polytetrafluoroethylene-lined reactor and react at 180 °C-200 °C for 10-13 h; after the reaction is complete, cool to room temperature and wash with a mixed solvent of cyclohexane and ethanol by centrifugation to obtain PMA nanosheets; Step 2: Add 0.015 g-0.016 g of iridium chloride to 11-12 mL of isopropanol and disperse by ultrasonication. Then add 1-2 mL of cyclohexane-dispersed PMA nanosheets and stir by ultrasonication and magnetic stirring to obtain mixed solution B. Pour the mixed solution B into a polytetrafluoroethylene-lined reactor and react at 110-150 °C for 6-10 h. After the reaction is completed, cool to room temperature and wash with ethanol by centrifugation to obtain the Ir / PMA composite material for proton exchange membrane water electrolysis anode material.

2. The preparation method according to claim 1, characterized in that: In steps 1 and 2, the rotation speed of the magnetic stirring is 350-450 rpm.

3. The preparation method according to claim 1, characterized in that: In step 1, the centrifugation speed is 8000-10000 rpm.

4. The preparation method according to claim 1, characterized in that: In step 2, the centrifugation speed is 10,000 to 12,000 rpm.

5. An Ir / PMA composite material prepared by the preparation method according to any one of claims 1 to 4.

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