Preparation method and application of integrated Ru-FeOOH / NF electrocatalyst for electrolytic water oxygen evolution

Abstract

The application belongs to the technical field of water electrolysis oxygen evolution reaction catalysis, and relates to a preparation method and application of a Ru-FeOOH / NF integrated electrocatalyst for water electrolysis oxygen evolution. The method comprises the following steps: foam nickel is sequentially immersed in an acetone solution, a hydrochloric acid solution and deionized water for ultrasonic cleaning, and is vacuum dried for standby; iron salt and ruthenium salt with a molar ratio of (0.1-5):(0.01-0.5) are dissolved in deionized water, then a certain amount of hydrogen peroxide is added, and the mixture is stirred uniformly to obtain a mixed solution; the mixed solution and the foam nickel are subjected to hydrothermal reaction at 90-130 DEG C for 5-12 h; then ultrasonic washing and vacuum drying are performed to obtain the Ru-FeOOH / NF electrocatalyst. The Ru-FeOOH composite catalyst is in-situ grown on the foam nickel through a simple one-step hydrothermal synthesis method, uniform dispersion and efficient catalysis of the catalyst are realized, and the method steps are simple and suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of catalytic technology for oxygen evolution reaction in water electrolysis, specifically relating to a method for preparing and applying an integrated Ru-FeOOH / NF electrocatalyst for oxygen evolution in water electrolysis. Background Technology

[0002] The oxygen evolution reaction (OER) in water electrolysis is a crucial step in the hydrogen production process, and its efficiency directly affects the overall energy conversion efficiency of the process. Existing OER catalysts such as RuO2 and IrO2 have been extensively studied due to their excellent catalytic performance, but their high cost limits their large-scale application. Therefore, developing low-cost, high-performance non-precious metal catalysts has become a current research hotspot.

[0003] Iron hydroxyl oxide (FeOOH), as a transition metal hydroxide, exhibits great potential in the oxygen evolution reaction (OER) of water electrolysis due to its abundant active sites and good stability. However, the catalytic activity of pure FeOOH still needs improvement. Nickel foam (NF), as a porous metal support, is widely used as an electrode material support due to its good conductivity, high specific surface area, and excellent mechanical properties. Some existing studies have reported methods to improve the OER performance of FeOOH loaded on nickel foam and doped with Ru. However, these methods generally suffer from drawbacks such as cumbersome preparation steps, uneven catalyst dispersion, and low catalytic performance. For example, a common method is to first grow FeOOH on nickel foam using chemical deposition, and then dope it with Ru using impregnation. However, this method has the following problems: first, it is difficult to control the morphology and distribution of FeOOH during chemical deposition, resulting in poor catalyst dispersion; second, when Ru is doped using impregnation, the distribution of Ru in FeOOH is uneven, easily forming agglomerates and affecting catalytic performance. Another approach is to directly grow Ru-FeOOH composite catalysts on nickel foam via electrochemical deposition. Although this method allows for catalyst preparation in one step, it is difficult to precisely control the Ru-Fe ratio and catalyst morphology during electrochemical deposition, leading to unstable catalytic performance. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of cumbersome preparation steps, uneven catalyst dispersion, and low catalytic performance in the prior art. It proposes a method for preparing Ru-FeOOH / NF integrated electrocatalyst for oxygen evolution in water electrolysis and its application. This method achieves uniform dispersion and high-efficiency catalysis by growing Ru-FeOOH composite catalyst in situ on nickel foam through a simple one-step hydrothermal synthesis method.

[0005] The technical solution of this invention is:

[0006] A method for preparing an integrated Ru-FeOOH / NF electrocatalyst for oxygen evolution in water electrolysis includes the following steps:

[0007] (1) Immerse the nickel foam in acetone solution and sonicate for 5-30 min to remove surface oil and impurities. Place the cleaned nickel foam in hydrochloric acid solution with a concentration of 1-3 mol / L and sonicate for 5-30 min to remove surface oxides. Then sonicate in deionized water for 5-30 min. Place the cleaned nickel foam in a vacuum dryer at 40-70 ℃ for 6-16 h for later use.

[0008] (2) Dissolve iron salt and ruthenium salt in deionized water with a molar ratio of (0.1~5):(0.01~0.5), then add a certain amount of hydrogen peroxide and stir until a mixed solution is obtained;

[0009] (3) Place the mixed solution from step (2) and the nickel foam treated in step (1) at a temperature of 90~130 °C for hydrothermal reaction for 5~12 h; then cool naturally to room temperature, ultrasonically wash the reacted nickel foam with a deionized water-ethanol mixed solution, and vacuum dry to obtain Ru-FeOOH / NF electrocatalyst.

[0010] Furthermore, step (1) involves pretreating the nickel foam, first preparing a piece of foam with a size of 2 × 3 cm. 2 The foamed nickel was immersed in acetone and sonicated for 10 min. Then, the cleaned foamed nickel was placed in 1 mol / L dilute hydrochloric acid and sonicated for 10 min, followed by sonication in deionized water for 10 min. It was then dried in a vacuum oven at 60 °C for 12 hours for later use.

[0011] Furthermore, in step (2), the molar ratio of iron salt to ruthenium salt is 10:1.

[0012] Furthermore, the iron salt in step (2) is FeSO4·7H2O, the ruthenium salt is RuCl3·3H2O, and the hydrogen peroxide is 30% H2O2 by mass.

[0013] Weigh 0.1–5 mmol FeSO4·7H2O, 0.01–0.5 mmol RuCl3·3H2O, and 0.1–5 mL of 30% H2O2, respectively, dissolve them in water, and stir until homogeneous to obtain a solution.

[0014] Further, 1 mmol FeSO4·7H2O, 0.1 mmol RuCl3·3H2O and 1 mL 30% H2O2 were dissolved in 14 mL of deionized water and stirred until homogeneous.

[0015] Furthermore, in step (3), the mixed solution and nickel foam are rapidly transferred to a polytetrafluoroethylene high-pressure sealed reactor and placed in a forced-air drying oven for reaction at 100 °C for 6 h; the reacted nickel foam is ultrasonically washed 3 to 4 times with a deionized water-ethanol mixed solution with a volume ratio of 1:1, and then dried in a vacuum oven at 40 to 70 °C for 6 to 16 hours to obtain the Ru-FeOOH / NF electrocatalyst.

[0016] This invention also protects the application of the Ru-FeOOH / NF electrocatalyst prepared by any of the above methods in water electrolysis.

[0017] Furthermore, the electrocatalyst serves as the working electrode and is applied to the oxygen evolution reaction in the process of catalyzing alkaline water electrolysis or alkaline medium water electrolysis to produce hydrogen.

[0018] The beneficial effects of this invention are:

[0019] (1) The preparation method of Ru-FeOOH / NF integrated electrocatalyst for water electrolysis and oxygen evolution provided by the present invention has the advantages of simple preparation steps and easy operation, and is suitable for large-scale production; the prepared catalyst has excellent water electrolysis and oxygen evolution performance, high energy conversion efficiency, and long water electrolysis and oxygen evolution life, and is expected to be widely used in the future field of water electrolysis and hydrogen production.

[0020] (2) The present invention first removes oil and oxides from the surface of nickel foam through pretreatment, and then uses wet chemical method to grow Ru-FeOOH composite catalyst in situ on nickel foam; during the growth process, by precisely controlling parameters such as the concentration of reactants, reaction time and temperature, uniform growth and efficient catalysis of the catalyst are achieved.

[0021] This invention prepares a three-dimensional structure composed of stacked two-dimensional sheet structures. The catalyst is uniformly dispersed, which can greatly increase the active area of ​​the catalyst, improve its oxygen evolution performance in water electrolysis, and ensure stable oxygen evolution performance in water electrolysis. The catalyst has strong bonding force with the electrode and a long service life. Attached Figure Description

[0022] Figure 1 The image shows a scanning electron microscope (SEM) image of the Ru-FeOOH / NF catalyst prepared in Example 1 of this invention.

[0023] Figure 2 This is a transmission electron microscope (TEM) image of the Ru-FeOOH / NF catalyst prepared in Example 1 of the present invention;

[0024] Figure 3The images shown are high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) images and elemental surface scans of the Ru-FeOOH / NF catalyst prepared in Example 1 of this invention; wherein, (a) is the overall HAADF-STEM image, (b) is an enlarged view of region A in (a), (c) is the surface scan of element O, (d) is the surface scan of element Fe, and (e) is the surface scan of element Ru.

[0025] Figure 4 The above are X-ray photoelectron spectroscopy (XPS) spectra of the Ru-FeOOH / NF catalyst prepared in Example 1 of this invention; where (a) is the Fe 2p spectrum and (b) is the Ru 3p spectrum.

[0026] Figure 5 Linear sweep voltammetry (LSV curve) of oxygen evolution in water electrolysis of the Ru-FeOOH / NF catalyst prepared in Example 1 of this invention.

[0027] Figure 6 The oxygen evolution stability test curve of the Ru-FeOOH / NF catalyst prepared in Example 1 of this invention is shown. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] To further understand the present invention, it will be further described in conjunction with the accompanying drawings and embodiments.

[0030] Example 1

[0031] This embodiment provides a method for preparing an integrated Ru-FeOOH / NF electrocatalyst for oxygen evolution in water electrolysis, comprising the following steps:

[0032] (1) Pre-treat the nickel foam by first preparing a piece of nickel foam with a size of 2 × 3 cm. 2 The nickel foam was immersed in acetone solution and sonicated for 10 minutes. Then, the cleaned nickel foam was placed in 1 mol / L dilute hydrochloric acid and sonicated for 10 minutes. Then, it was sonicated in deionized water for 10 minutes and dried in a vacuum oven at 60 °C for 12 hours for later use.

[0033] (2) Dissolve 1 mmol FeSO4·7H2O, 0.1 mmol RuCl3·3H2O and 1 mL H2O2 (mass fraction 30%) in 14 mL of deionized water and stir well to form a mixed solution;

[0034] (3) The mixed solution and the pretreated nickel foam were quickly transferred to a 25 mL polytetrafluoroethylene reactor, placed in a forced-air drying oven, reacted at 100 °C for 6 h, and then naturally cooled to room temperature. The reacted nickel foam was ultrasonically washed three times with a 1:1 volume ratio of deionized water-ethanol mixed solution, and then dried in a vacuum oven at 60 °C for 12 h to obtain Ru-FeOOH / NF electrocatalyst.

[0035] The prepared Ru-FeOOH / NF electrocatalyst was analyzed by scanning electron microscopy, and the results were as follows: Figure 1 The SEM image shown shows that the Ru-FeOOH / NF catalyst has a three-dimensional structure of two-dimensional sheet stacking.

[0036] The prepared Ru-FeOOH / NF electrocatalyst was analyzed by transmission electron microscopy, and the results were as follows: Figure 2 The TEM image shown further illustrates that the Ru-FeOOH / NF catalyst exhibits an ultrathin sheet-like structure.

[0037] The prepared Ru-FeOOH / NF electrocatalyst was subjected to high-angle annular dark-field scanning transmission electron microscopy and elemental surface scanning analysis, yielding the following results: Figure 3 The HAADF-STEM and elemental surface scans are shown. Figure 3 The HAADF-STEM images in (a) and (b) further illustrate that the Ru-FeOOH / NF catalyst exhibits an ultrathin layered structure. Figure 3 The elemental surface scans of (c), (d), and (e) show that Fe, Ru, and O are uniformly distributed on the nickel foam framework, indicating that the prepared catalyst is relatively uniform.

[0038] Figure 4 The XPS spectrum of the Ru-FeOOH / NF catalyst is shown below. Figure 4 As can be seen in (a), Fe 2p 3 / 2 and Fe 2p 1 / 2 The peaks are located at 710.64 and 724.49 eV, respectively, corresponding to trivalent Fe. Figure 4 As can be seen in (b), Ru 2p 3 / 2 and Ru2p 1 / 2 The peaks are located at 462.70 and 484.98 eV, respectively, corresponding to trivalent Ru.

[0039] Experimental Example 1

[0040] The Ru-FeOOH / NF electrocatalyst prepared in Example 1 was used to catalyze the oxygen evolution reaction in the process of producing hydrogen through alkaline water electrolysis or alkaline medium water electrolysis. The application method is as follows:

[0041] All electrochemical experiments were conducted at room temperature using a CHI 660E electrochemical workstation from Shanghai Chenhua, employing a standard three-electrode system: a Ru-FeOOH / NF electrocatalyst as the working electrode, a mercuric oxide electrode as the reference electrode, and a carbon rod as the counter electrode. The electrolyte was a 1 M KOH solution, and the current density for chronoamperometry-time stability testing was 100 mA / cm². 2 .

[0042] Figure 5 The figure shows the LSV curves for oxygen evolution in water electrolysis using the Ru-FeOOH / NF catalyst. It can be seen from the figure that at a current density of 100 mA cm⁻¹... -2 At that time, the overpotential of Ru-FeOOH / NF was only 240 mV, which was significantly lower than that of FeOOH / NF catalyst (349 mV), indicating that Ru-FeOOH / NF catalyst has excellent OER activity.

[0043] Figure 6 The figure shows the chronoamperometry-time stability test results of the Ru-FeOOH / NF catalyst. As can be seen from the figure, after 100 hours of operation, the change in current density is very small, indicating that the Ru-FeOOH / NF catalyst has excellent stability in alkaline electrolytes.

[0044] Example 2

[0045] This embodiment provides a method for preparing an integrated Ru-FeOOH / NF electrocatalyst for oxygen evolution in water electrolysis, comprising the following steps:

[0046] (1) Pre-treat the nickel foam by first preparing a piece of nickel foam with a size of 2 × 3 cm. 2 The foamed nickel was immersed in acetone solution and sonicated for 5 minutes. Then, the cleaned foamed nickel was placed in 2 mol / L dilute hydrochloric acid and sonicated for 5 minutes. Then, it was sonicated in deionized water for 5 minutes and dried in a vacuum oven at 40 ℃ for 16 hours for later use.

[0047] (2) Dissolve 0.1 mmol FeSO4·7H2O, 0.01 mmol RuCl3·3H2O and 0.1 mL H2O2 (mass fraction 30%) in 14.9 mL of deionized water and stir well to form a mixed solution;

[0048] (3) The mixed solution and the pretreated nickel foam were quickly transferred to a 25 mL polytetrafluoroethylene reactor, placed in a forced-air drying oven, reacted at 90 °C for 12 h, and then naturally cooled to room temperature. The reacted nickel foam was ultrasonically washed three times with a 1:1 volume ratio of deionized water-ethanol mixed solution, and then dried in a vacuum oven at 40 °C for 16 h to obtain Ru-FeOOH / NF electrocatalyst.

[0049] Example 3

[0050] This embodiment provides a method for preparing an integrated Ru-FeOOH / NF electrocatalyst for oxygen evolution in water electrolysis, comprising the following steps:

[0051] (1) Pre-treat the nickel foam by first preparing a piece of nickel foam with a size of 2 × 3 cm. 2 The nickel foam was immersed in acetone solution and sonicated for 30 minutes. Then, the cleaned nickel foam was placed in 3 mol / L dilute hydrochloric acid and sonicated for 30 minutes. Then, it was sonicated in deionized water for 30 minutes and dried in a vacuum oven at 70 °C for 6 hours for later use.

[0052] (2) Dissolve 5 mmol FeSO4·7H2O, 0.5 mmol RuCl3·3H2O and 5 mL H2O2 (mass fraction 30%) in 10 mL of deionized water and stir well to form a mixed solution;

[0053] (3) The mixed solution and the pretreated nickel foam were quickly transferred to a 25 mL polytetrafluoroethylene reactor, placed in a forced-air drying oven, reacted at 130 °C for 5 h, and then naturally cooled to room temperature. The reacted nickel foam was ultrasonically washed 4 times with a 1:1 volume ratio deionized water-ethanol mixed solution, and then dried in a vacuum oven at 70 °C for 6 h to obtain Ru-FeOOH / NF electrocatalyst.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., 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 an integrated Ru-FeOOH / NF electrocatalyst for oxygen evolution in water electrolysis, comprising the following steps: (1) Pretreatment of nickel foam: First, prepare nickel foam with a size of 2×3cm. 2 The foamed nickel was immersed in acetone solution and sonicated for 10 minutes. Then, the cleaned foamed nickel was placed in 1 mol / L dilute hydrochloric acid and sonicated for 10 minutes. Then, it was sonicated in deionized water for 10 minutes and dried in a vacuum oven at 60°C for 12 hours to obtain pretreated foamed nickel. (2) Dissolve 1 mmol FeSO4·7H2O, 0.1 mmol RuCl3·3H2O and 1 mL of 30% H2O2 in 14 mL of deionized water and stir well to form a mixed solution; (3) The mixed solution and the pretreated nickel foam were quickly transferred to a 25 mL polytetrafluoroethylene reactor, placed in a forced-air drying oven, reacted at 100 °C for 6 h, and then naturally cooled to room temperature to obtain the reacted nickel foam; the reacted nickel foam was ultrasonically washed three times with a mixed solution of deionized water and ethanol in a volume ratio of 1:1, and then dried in a vacuum oven at 60 °C for 12 h to obtain the Ru-FeOOH / NF integrated electrocatalyst. The Ru-FeOOH / NF integrated electrocatalyst operates at a current density of 100 mA·cm⁻¹ -2 At that time, the overpotential was 240mV; The overpotential was obtained based on the oxygen evolution potential (LSV) curve of the Ru-FeOOH / NF integrated electrocatalyst during water electrolysis. The LSV curve was obtained by the following method: Under normal temperature conditions, tests were conducted using a CHI 660E electrochemical workstation from Shanghai Chenhua, employing a conventional three-electrode system: a Ru-FeOOH / NF integrated electrocatalyst as the working electrode, a mercuric oxide electrode as the reference electrode, a carbon rod as the counter electrode, and a 1M KOH solution as the electrolyte.

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