Preparation method and application of electrolytic seawater catalyst based on local acidic environment

Abstract

This invention relates to the field of electrocatalysis, and discloses a method for preparing and applying a seawater electrolysis catalyst based on a locally acidic environment. The current collector is simply cleaned, and Fe₂O₃ is further grown on it using a molten salt-assisted method. Finally, it is further modified using ruthenium trichloride plasma exchange to obtain a novel electrocatalyst (Ru / Fe₂O₃) with locally acidic conditions. 3‑x ). Ru / Fe2O 3‑x Not only does it exhibit excellent hydrogen evolution performance, but the localized acidic environment generated in this catalyst can also effectively suppress Ca2+ evolution. 2+ and Mg 2+ The precipitation occurs when Na is present. + Even when the cathode of the mediated asymmetric electrolytic cell is used, it can maintain stable operation for a long time.

Description

Technical Field

[0001] This invention relates to the field of industrial seawater electrolysis for hydrogen production, specifically to a method for preparing a seawater electrolysis catalyst based on a locally acidic environment and its application in an asymmetric electrolyzer. Background Technology

[0002] With the emergence of the energy crisis and environmental pollution, the demand for clean and sustainable energy is constantly intensifying. Hydrogen (H2), as a green energy carrier, has attracted widespread attention due to its high energy density. Currently, although noble metal Pt catalysts possess high catalytic activity, their low reserves, high cost, and poor stability severely hinder their industrial application. Meanwhile, the hydrogen evolution reaction (HER) under alkaline seawater conditions is affected by Cl... - The erosion and the occurrence of Ca 2+ and Mg 2+ Precipitation can lead to catalyst poisoning, therefore, there is an urgent need to develop efficient, low-cost, highly active and durable seawater electrolysis catalysts.

[0003] In recent years, ruthenium-based catalysts have been extensively studied due to their excellent corrosion resistance and relatively low cost. Since the spatial distribution of small molecules at the solid-liquid interface is beneficial for improving the kinetics of catalytic reactions, constructing a localized chemical environment around the catalyst during the HER process is considered an effective way to improve catalyst activity and stability. However, to our knowledge, there is currently very little research on the construction of a localized acidic environment during the HER process in seawater electrolysis. Therefore, there is an urgent need to explore a general method to create a localized acidic environment to improve the HER performance in seawater electrolysis while inhibiting Ca2+. 2+ and Mg 2+ The precipitation occurs. Summary of the Invention

[0004] 1. The purpose of this invention is to provide a method for preparing a seawater electrolysis catalyst based on a locally acidic environment and its application in an asymmetric electrolyzer. Fe₂O₃ is grown on a current collector using a molten salt-assisted method, and an oxygen-vacancy-rich ruthenium-based electrocatalyst (Ru / Fe₂O₃) is obtained using a plasma exchange method. 3-x Compared with traditional HER electrocatalyst methods, this invention can suppress Ca2+ while ensuring high catalytic performance. 2+ and Mg 2+ The precipitation process can also maintain long-term catalytic stability in asymmetric electrolyzers, which is of great value for future practical applications.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] The present invention provides a method for preparing a seawater electrolysis catalyst based on a locally acidic environment, which can be achieved through the following technical route:

[0007] (1) Pretreatment of the current collector: After cutting the current collector (foam iron) into appropriate sizes, it is immersed in acetone, deionized water and ethanol respectively for ultrasonic treatment and then dried in a vacuum oven.

[0008] (2) Preparation of Fe2O3 precursor: Fe(NO3)3·9H2O was heated to 100-200℃ in an oven and reacted for 10-60 min. Then, foamed iron was added and reacted for 1-20 min, followed by natural cooling. The reacted foamed iron was repeatedly rinsed with deionized water and ethanol and then dried in a vacuum oven.

[0009] (3)Ru / Fe2O 3-x Preparation: The synthesized Fe2O3 precursor was soaked in a treated ruthenium trichloride solution for 30-400 min, then rinsed repeatedly with deionized water and ethanol, and dried in a vacuum oven.

[0010] According to the preparation method of the technical route, the characteristic is that: in step (1), the foamed iron is cut into 1cm*2cm pieces, immersed in acetone, ethanol and deionized water respectively, ultrasonically treated for 10-40min and then dried to remove organic matter and oxides from the surface of the foamed iron.

[0011] According to the preparation method of the technical route, the characteristic is that the amount of Fe(NO3)3·9H2O used in step (2) is between 1 and 10g, so as to synthesize Fe2O3 precursor with relatively uniform morphology and size.

[0012] According to the preparation method of the technical route, the characteristic is that the amount of ruthenium trichloride used in step (3) is between 1 and 10 g.

[0013] This invention provides a method for preparing a seawater electrolysis catalyst based on a locally acidic environment. Fe₂O₃ is grown on a foamed iron current collector using a molten salt-assisted method, and an oxygen-vacancy-rich ruthenium-based electrocatalyst is further obtained using an ion exchange method. Compared with conventional methods for preparing HER electrocatalysts, this invention ensures both high catalytic efficiency and long-term stability, which has significant value for future practical applications.

[0014] As a further feature of the present invention: the present invention mainly inhibits Ca while inducing the generation of a local acidic environment by oxygen vacancies around the catalyst. 2+ and Mg 2+ The precipitation occurs and integrates into Na. + In a mediated asymmetric electrolyzer, a locally acidic environment is created by adjusting the hydrogen adsorption energy and electronic structure using oxygen vacancies. Simultaneously, the asymmetric electrolyzer can prevent Cl...- From cathode to anode, the competitive chlorine evolution reaction (CLOR) was effectively avoided, reducing the overall water splitting voltage. Furthermore, maintaining flowing seawater with a pH below 9.5 mitigated precipitation issues during the HER process at the cathode. Therefore, this study paves a new pathway for designing catalysts that create localized chemical environments during seawater electrolysis HER. Detailed Implementation

[0015] The technical features of this invention are described below with reference to specific experimental schemes and accompanying drawings, but this invention is not limited thereto. Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; the instruments and materials described, unless otherwise specified, are all commercially available.

[0016] Example 1

[0017] A method for preparing a seawater electrolysis catalyst based on a locally acidic environment and its application in an asymmetric electrolyzer includes the following steps:

[0018] (1) In this embodiment, 1cm*2cm foam iron is cut, and foam nickel is placed in acetone, deionized water and ethanol respectively and sonicated for 30min. After vacuum drying, it is ready for use.

[0019] (2) Weigh 5g of Fe(NO3)3·9H2O and heat it in an oven to 150℃ for 20min. Then add the foamed iron and react for 5min. Let it cool naturally. After the reaction, the foamed iron is repeatedly washed with deionized water and ethanol and then dried in a vacuum oven to obtain the Fe2O3 precursor.

[0020] (3) The synthesized Fe2O3 precursor was immersed in a treated ruthenium trichloride solution for 360 min, then rinsed repeatedly with deionized water and ethanol, and dried in a vacuum oven to obtain Ru / Fe2O3. 3-x X-ray diffraction (XRD) images revealed the presence of Fe2O in the catalyst. 3， Three different crystal phases: Ru and Fe Figure 1 The Ru / Fe2O2 ratio can be seen from the high-power transmission electron microscopy (HRTEM) images. 3-x The presence of discontinuous lattice fringes and blurred or even missing lattice sites indicates the presence of oxygen vacancies. Figure 2 ). Utilizing electron paramagnetic resonance spectroscopy ( Figure 3 This demonstrates the presence of numerous oxygen vacancies in the catalyst. Simultaneously, in-situ Raman spectroscopy was used to confirm the presence of these vacancies. Figure 4 ) was found at 1750cm -1 A significant peak was observed at this point, which is due to H3O +The presence of reaction intermediates indicates the formation of a locally acidic environment during the HER process. This catalyst exhibits excellent stability, capable of stable operation for over 1000 hours in 0.1 M KOH + seawater conditions. Figure 5 Simultaneously using Ru / Fe2O 3-x As Na + The cathode of a mediated asymmetric electrolyzer, in a natural seawater solution, at 0.1 A cm⁻¹ -2 It can operate stably for more than 140 hours at a current density. Figure 6 It can operate stably for 96 hours under simulated seawater conditions. Figure 7 ).

[0021] Example 2

[0022] A method for preparing a seawater electrolysis catalyst based on a locally acidic environment and its application in an asymmetric electrolyzer includes the following steps:

[0023] (1) In this embodiment, 1cm*2cm foam iron is cut, and foam nickel is placed in acetone, deionized water and ethanol respectively and sonicated for 40min. After vacuum drying, it is ready for use.

[0024] (2) Weigh 5g of Fe(NO3)3·9H2O and heat it in an oven to 150℃ for 20min. Then add the foamed iron and react for 1min. Let it cool naturally. After the reaction, the foamed iron is repeatedly washed with deionized water and ethanol and then dried in a vacuum oven to obtain the Fe2O3 precursor.

[0025] (3) The synthesized Fe2O3 precursor was immersed in a treated ruthenium trichloride solution for 360 min, then rinsed repeatedly with deionized water and ethanol, and dried in a vacuum oven to obtain Ru / Fe2O3. 3-x Its scanning electron microscope (SEM) is as follows: Figure 8 As shown, the material exhibits a nanosheet morphology. This catalyst, under 0.1 M KOH + seawater conditions, requires only a 294 mV overpotential to drive a 1.0 A cm⁻¹ flow rate. -2 The current density exhibits excellent HER activity. Figure 9 ). Attached image description:

[0026] Figure 1 Ru / Fe2O obtained in Example 1 3-x X-ray diffraction pattern;

[0027] Figure 2 Ru / Fe2O obtained in Example 1 3-x High-magnification transmission microscope images;

[0028] Figure 3Ru / Fe2O obtained in Example 1 3-x Electron paramagnetic resonance spectrum;

[0029] Figure 4 Ru / Fe2O obtained in Example 1 3-x In-situ Raman spectroscopy results;

[0030] Figure 5 Ru / Fe2O obtained in Example 1 3-x The stability test graph is shown. The X-axis represents the test time (h), and the Y-axis represents the operating voltage (V).

[0031] Figure 6 Example 1 of this invention uses Na2O assembled under natural seawater conditions. + Performance testing of the mediated asymmetric electrolyzer. The X-axis represents the test time (h), and the Y-axis represents the operating voltage (V).

[0032] Figure 7 Example 1 of this invention assembles a simulated seawater Na + Performance testing of the mediated asymmetric electrolyzer. The X-axis represents the test time (h), and the Y-axis represents the operating voltage (V).

[0033] Figure 8 Ru / Fe2O obtained in Example 2 3-x Scanning electron microscope images.

[0034] Figure 9 Ru / Fe2O obtained in Example 2 3-x HER performance was tested under 0.1M KOH + seawater conditions. The X-axis represents the operating voltage (V), and the Y-axis represents the current density (mA / cm²). -2 ).

Claims

1. A method for preparing a seawater electrolysis catalyst based on a locally acidic environment, characterized in that: The foamed iron was subjected to a simple cleaning process, and Fe2O3 was further grown on it using a molten salt-assisted method. Finally, it was further modified by ruthenium trichloride plasma exchange to obtain an electrocatalyst Ru / Fe2O3 with a locally acidic environment. 3-x The specific steps are as follows: (1) Pretreatment of foamed iron: After cutting the foamed iron into 1cm*2cm sizes, it is immersed in acetone, deionized water and ethanol respectively, ultrasonically treated for 10-40min and then dried in a vacuum oven; (2) Preparation of Fe2O3 precursor: Fe(NO3)3·9H2O was heated to 100~200 ℃ in an oven and reacted for 10~60 min. Then, foamed iron was added and reacted for 1~20 min. After natural cooling, the foamed iron was repeatedly rinsed with deionized water and ethanol and then dried in a vacuum oven. (3)Ru / Fe2O 3-x Preparation: The synthesized Fe2O3 precursor was soaked in a treated ruthenium trichloride solution for 30-400 min, then rinsed repeatedly with deionized water and ethanol and dried in a vacuum oven; In step (2), the amount of Fe(NO3)3·9H2O used is 1~10g; The amount of ruthenium trichloride used in step (3) is between 1 and 10 g.

2. A type of Na + The mediated asymmetric electrolyzer is characterized by, The catalyst obtained by the preparation method according to claim 1 is used as the cathode of the asymmetric electrolyzer.

3. The asymmetric electrolytic cell according to claim 2, characterized in that, At 0.1 A cm -2 It can operate stably for more than 140 hours at a current density.

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