An iron-doped ruthenium dioxide electrocatalyst, its preparation method and application

Abstract

This invention belongs to the field of electrocatalyst technology, specifically relating to an iron-doped ruthenium dioxide electrocatalyst, its preparation method, and its applications. Addressing the characteristics of ruthenium dioxide exhibiting both high activity and low stability in acidic electrolytes, this invention utilizes a process involving salt template-assisted confined synthesis, iron doping modification, grinding and calcination, acid washing to create pores, and centrifugal washing and drying. This process preferentially deposits the Fe-Ru-O active species generated from the thermal decomposition of ruthenium acetylacetone and iron acetylacetone onto the surface of a non-equilibrium salt template. After removing the template with acid washing, a porous catalyst with a high specific surface area is effectively formed. The iron-doped ruthenium dioxide material prepared by this invention, possessing both high oxygen evolution reaction activity and excellent long-term operational stability, can serve as a high-performance, low-cost electrocatalyst for acidic electrolytes, showing promising application prospects.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst technology, specifically relating to an iron-doped ruthenium dioxide electrocatalyst, its preparation method, and its application. Background Technology

[0002] Proton exchange membrane (PEM) water electrolysis technology, with its high-purity hydrogen production, rapid dynamic response, compact system configuration, and good compatibility with intermittent power sources such as wind and solar energy, is gradually becoming one of the mainstream pathways for large-scale green hydrogen production. However, the widespread adoption of this technology is still constrained by issues such as the high cost of anode catalysts, insufficient long-term operational stability, and the scarcity of precious metals such as iridium and ruthenium. Ruthenium dioxide (RuO2) is considered a highly promising catalytic material due to its excellent intrinsic oxygen evolution reaction (OER) activity. However, RuO2 is prone to the dissolution of high-valence ruthenium species under acidic operating conditions, causing catalytic layer structure collapse and activity decay, and its durability is far from meeting the requirements for industrial-scale lifespan.

[0003] In recent years, iron (Fe) doping has been considered an effective strategy for regulating the catalytic performance of RuO2. However, existing Fe-doped systems have revealed several prominent problems: First, Fe is prone to dissolution at the acidic anodic oxygen evolution reaction (OER) potential, leading to irreversible loss of active sites and accelerating catalyst degradation; second, the difference in ionic radii between Fe and Ru easily induces lattice distortion or phase separation, destroying the integrity of the original rutile structure and weakening the long-range stability of the catalyst; third, Fe doping often fails to simultaneously improve activity and stability—mild doping can improve intrinsic activity, but structural reinforcement is insufficient; excessive doping dilutes the surface Ru active sites, sacrificing catalytic efficiency. Therefore, there is an urgent need to develop new approaches for the preparation of Fe-doped RuO2 electrocatalysts. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, the present invention aims to provide a method for preparing and applying an iron-doped ruthenium dioxide electrocatalyst. The method involves steps such as blending and grinding raw materials with a non-equilibrium salt template, calcination and oxidation, water quenching and rapid cooling, acid washing and drying to obtain an Fe-doped RuO2 acidic oxygen evolution electrocatalyst. This effectively enhances the OER catalytic activity and long-term operational stability of RuO2 in acidic electrolytes, and expands the candidate material system for proton exchange membrane water electrolysis anode catalysts.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing an iron-doped ruthenium dioxide electrocatalyst, comprising the following steps: Ruthenium acetylacetonate (Ru(acac)3), iron acetylacetonate (Fe(acac)3), sodium chloride (NaCl), and lithium chloride (LiCl) were mixed and ground to obtain a catalyst precursor. The catalyst precursor was calcined to obtain FeRuO x / NaCl / LiCl complex; The FeRuO2 was subjected to water quenching and rapid cooling. x / NaCl / LiCl complex, to obtain cooled FeRuO x / NaCl / LiCl complex; FeRuO after pickling and cooling x The NaCl / LiCl complex was centrifuged, washed with water, and dried to obtain the iron-doped ruthenium dioxide electrocatalyst.

[0006] A second aspect of the present invention provides an iron-doped ruthenium dioxide electrocatalyst prepared by the preparation method described in the first aspect.

[0007] A third aspect of the present invention provides the application of the iron-doped ruthenium dioxide electrocatalyst described in the second aspect in the electrocatalytic oxygen evolution reaction in acidic media.

[0008] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The non-equilibrium salt template system of the present invention has confined pore-forming properties and anti-sintering ability. In the present invention, the non-equilibrium salt template system is sodium chloride and lithium chloride. The difference in particle size between the two allows them to synergistically play the dual role of pore-forming agent and morphology template under high temperature heat treatment conditions, thereby obtaining an iron-doped ruthenium dioxide electrocatalyst with higher electrocatalytic activity.

[0009] On the one hand, the molecular particle sizes of sodium chloride and lithium chloride differ, and the nanoscale gaps created when these two salts are stacked together perfectly match those of ruthenium acetylacetone and iron acetylacetone, helping to fix ruthenium acetylacetone and iron acetylacetone molecules within the gaps between the salt templates. In other words, the non-equilibrium salt template acts as a "bed" for the reaction, facilitating molecular-level dispersion and making it easier to obtain iron-doped ruthenium dioxide electrocatalysts. On the other hand, during high-temperature calcination, the solid salt particles physically isolate the metal precursors such as ruthenium acetylacetone and iron acetylacetone, preventing direct contact and sintering between adjacent particles. This effectively inhibits excessive growth and agglomeration of RuO2 grains, allowing the iron-doped ruthenium dioxide electrocatalyst to retain more highly active catalytic sites.

[0010] (2) This invention utilizes water quenching and rapid cooling to generate intense stress, which helps to improve the electrocatalytic activity of iron-doped ruthenium dioxide. This invention employs a water quenching and rapid cooling method, where the intense lattice stress generated by rapid cooling in FeRuO2... xInducing lattice distortion within the crystal can further modulate the electronic structure of the catalyst, helping to enhance the electrocatalytic activity of iron-doped ruthenium dioxide. Compared to natural cooling or slow cooling, water quenching retains more structural defects such as oxygen vacancies. These defects can serve as additional active centers or cooperating sites, further promoting the electrocatalytic reaction kinetics.

[0011] (3) The present invention performs acid washing on the calcined product, simultaneously achieving the dissolution and removal of NaCl and LiCl salt templates and the removal of unstable FeRuO x Selective etching of metal oxide species. The Fe-Ru-O active species generated by the thermal decomposition of ruthenium acetylacetonate and iron acetylacetonate preferentially deposit on the surface of the non-equilibrium salt template. After removing the template by acid washing, a porous catalyst with a high specific surface area is effectively formed. Attached Figure Description

[0012] Figure 1 This is a flowchart of the preparation method in Example 1 of the present invention.

[0013] Figure 2 The X-ray diffraction (XRD) patterns of the electrocatalysts prepared in Example 1 and Comparative Examples 1-2 of this invention are shown.

[0014] Figure 3 This is a transmission electron microscope (TEM) image of Embodiment 1 of the present invention.

[0015] Figure 4 The images shown are energy-dispersive X-ray spectroscopy (EDX) images of the electrocatalyst prepared in Example 1 of this invention. (a) is the oxygen distribution map, (b) is the ruthenium distribution map, and (c) is the iron distribution map.

[0016] Figure 5 Linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in Example 1 and Comparative Examples 1-4 in 0.5M H2SO4 electrolyte.

[0017] Figure 6 Tafel curves of the electrocatalysts prepared in Example 1 and Comparative Examples 1-4 in 0.5M H2SO4 electrolyte.

[0018] Figure 7 A comparison of the LSV curves of the electrocatalyst prepared in Example 1 before and after 5000 cyclic voltammetry (CV) tests in 0.5 M H2SO4 electrolyte.

[0019] Figure 8 The graph shows the constant current (CP) stability test of the electrocatalyst prepared in Example 1 in a 0.5 M H2SO4 electrolyte.

[0020] Figure 9Linear sweep voltammetry (LSV) curves of the electrocatalysts prepared for Example 1 and Comparative Example 5 in 0.5 M H2SO4 electrolyte.

[0021] Figure 10 Tafel curves of the electrocatalysts prepared in Example 1 and Comparative Example 5 in 0.5 M H2SO4 electrolyte.

[0022] Figure 11 Comparison of linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in Example 1 and Comparative Example 6 in 0.5 M H2SO4 electrolyte at different times.

[0023] Figure 12 Linear sweep voltammetry (LSV) curves of the electrocatalysts prepared for Example 1 and Comparative Example 7 in 0.5 M H2SO4 electrolyte.

[0024] Figure 13 Linear sweep voltammetry (LSV) curves of the electrocatalysts prepared for Examples 1 and Comparative Examples 8-10 in 0.5 M H2SO4 electrolyte.

[0025] Figure 14 Linear sweep voltammetry (LSV) curves of the electrocatalysts prepared for comparative examples 11-13 in 0.5 M H2SO4 electrolyte.

[0026] Figure 15 Linear sweep voltammetry (LSV) curves of the electrocatalysts prepared for Example 1 and Comparative Example 14 in 0.5 M H2SO4 electrolyte. Detailed Implementation

[0027] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0029] This invention provides a method for preparing an iron-doped ruthenium dioxide electrocatalyst, comprising the following steps: Ruthenium acetylacetonate (Ru(acac)3), iron acetylacetonate (Fe(acac)3), sodium chloride (NaCl), and lithium chloride (LiCl) were mixed and ground to obtain a catalyst precursor. The catalyst precursor was calcined to obtain FeRuO x / NaCl / LiCl complex; The FeRuO2 was subjected to water quenching and rapid cooling. x / NaCl / LiCl complex, to obtain cooled FeRuO x / NaCl / LiCl complex; FeRuO after pickling and cooling x The NaCl / LiCl complex was centrifuged, washed with water, and dried to obtain the iron-doped ruthenium dioxide electrocatalyst.

[0030] In this invention, the term "FeRuO" is used. x "Refers to iron-doped ruthenium dioxide catalysts".

[0031] In this invention, the term "FeRuO" is used. x "NaCl / LiCl complex" refers to a mixture of iron-doped ruthenium dioxide produced during calcination oxidation, along with unoxidized sodium chloride and lithium chloride.

[0032] In this invention, because Fe 3+ and Ru 4+ The ionic radii of the two molecules are similar, and Fe doping helps to regulate the electronic structure of the catalyst. Therefore, Fe doping has a positive effect on the catalytic performance of RuO2.

[0033] In some embodiments of the present invention, the molar ratio of ruthenium acetylacetone to iron acetylacetone is 9-19:1.

[0034] Preferably, the molar ratio of ruthenium acetylacetonate to iron acetylacetonate is 19:1.

[0035] In some embodiments of the present invention, the mass ratio of sodium chloride to lithium chloride is 2:2.5-3.5.

[0036] Preferably, the mass ratio of sodium chloride to lithium chloride is 2:3.

[0037] In some embodiments of the present invention, the total amount of ruthenium acetylacetonate and iron acetylacetonate is in a mass ratio of 0.2-0.3 mmol to 200 mg of sodium chloride and lithium chloride.

[0038] Preferably, the total amount of ruthenium acetylacetonate and iron acetylacetonate is in a mass ratio of 0.2 mmol to 200 mg of sodium chloride and lithium chloride.

[0039] In some embodiments of the present invention, ruthenium acetylacetonate, iron acetylacetonate, sodium chloride, and lithium chloride are mixed and then ground for at least 15 minutes to achieve uniform mixing of acetylacetonate salt and non-equilibrium salt templates.

[0040] In this invention, the term "non-equilibrium salt template" refers to sodium chloride and lithium chloride. The inventors discovered in their research that FeRuO generated using a single salt template... x The catalytic activity of the catalyst is not as good as that of FeRuO formed by sodium chloride and lithium chloride in a salt template mass ratio of 2:3. x The catalytic activity of the catalyst. Furthermore, replacing the salt template with other chlorides containing transition metals leads to co-doping.

[0041] Preferably, the grinding time after mixing ruthenium acetylacetonate, iron acetylacetonate, sodium chloride, and lithium chloride is 15 min.

[0042] In some embodiments of the present invention, the calcination treatment step includes: heating to 340-360 °C at a heating rate of 3-6 °C / min and holding at that temperature for 1.5-2.5 h.

[0043] Preferably, the calcination treatment step is as follows: heating to 350 °C at a heating rate of 5 °C / min and holding at that temperature for 2 h. In this invention, if the calcination temperature is too low, below 350 °C, the long-term operational stability of the prepared electrocatalyst will decrease; if the calcination temperature is too high, above 350 °C, the catalytic activity of the prepared electrocatalyst will decrease.

[0044] In some embodiments of the present invention, the calcination process is carried out in an air atmosphere.

[0045] In some embodiments of the present invention, the calcined FeRuO is immediately removed. x The NaCl / LiCl complex was subjected to water quenching and rapid cooling.

[0046] In some embodiments of the present invention, the water quenching step includes immersing in water at room temperature for 4-6 minutes.

[0047] Optionally, the water used in the water quenching and cooling process includes one or both of deionized water and distilled water.

[0048] Preferably, the water quenching and rapid cooling process involves immersing the sample in deionized water at room temperature for 5 minutes.

[0049] In some embodiments of the present invention, the pickling step includes: using dilute hydrochloric acid to treat the cooled FeRuO xThe NaCl / LiCl complex was acid-washed for 2-12 h with a dilute hydrochloric acid concentration of 0.1-0.3 mol / L. FeRuO x The ratio of the NaCl / LiCl complex to dilute hydrochloric acid is approximately 0.35 g: 20 mL.

[0050] Preferably, the acid washing process involves an acid washing time of 8 hours and a dilute hydrochloric acid concentration of 0.1 mol / L. This invention achieves multiple regulatory effects by precisely controlling the acid washing time and dilute hydrochloric acid concentration: on the one hand, it moderately removes excess Fe species from the surface, optimizing the Fe-Ru-O coordination environment; on the other hand, it lightly etches the RuO2 crystal phase, inducing the generation of a small number of oxygen vacancies, further regulating the electronic structure and surface chemical state, and synergistically promoting the improvement of catalytic performance. The inventors found in their research that if the acid washing time is too short, below 8 hours, it will be detrimental to the removal of salt templates and unstable oxides; if the acid washing time is too long, above 8 hours, it will lead to a decrease in the long-term operational stability of the electrocatalyst.

[0051] In some embodiments of the present invention, after acid washing, the mixture is centrifuged at least three times at a speed of 3800-4200 rpm for 4-6 minutes.

[0052] Preferably, after acid washing, the sample is centrifuged three times at 4000 rpm for 5 minutes.

[0053] In some embodiments of the present invention, the water washing step includes washing with water until the pH of the washing solution is 6.8-7.2.

[0054] Optionally, the water used in the washing process includes one or both of deionized water and distilled water.

[0055] In some embodiments of the present invention, the drying is performed at 70-90 °C for 11-13 h.

[0056] Preferably, the drying process is performed at 80 °C and normal pressure for 12 h.

[0057] The preparation method of the present invention does not require the use of solvents or co-solvents for dispersion, which simplifies the process, reduces costs, and makes it easy to scale up production.

[0058] The present invention also provides an iron-doped ruthenium dioxide electrocatalyst prepared by the method for preparing the iron-doped ruthenium dioxide electrocatalyst.

[0059] The iron-doped ruthenium dioxide electrocatalyst prepared by this invention has a porous structure with a high specific surface area. This porous structure increases the electrocatalytic active surface area of ​​the catalyst and promotes the mass transfer efficiency of water molecules, hydrogen ions and oxygen molecules in the OER electrocatalysis process in acidic electrolyte.

[0060] The present invention also provides the application of the iron-doped ruthenium dioxide electrocatalyst in the electrocatalytic oxygen evolution reaction in acidic media.

[0061] In some embodiments of the present invention, the acidic medium is a 0.5M H2SO4 electrolyte.

[0062] The iron-doped ruthenium dioxide electrocatalyst prepared by this invention reduces the overpotential of the OER reaction and enhances the catalytic activity of the electrocatalyst. Preferably, in a 0.5 M H₂SO₄ electrolyte, at 10 mA / cm², the catalytic activity is [not specified in the original text]. 2 At the specified current density, the overpotential of the iron-doped ruthenium dioxide electrocatalyst prepared in this invention is 184 mV; the Tafel slope is 56.24 mV / dec.

[0063] The iron-doped ruthenium dioxide electrocatalyst prepared by this invention exhibits good long-term operational stability at 10 mA / cm². 2 It can operate stably for more than 180 hours at current density.

[0064] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0065] Example 1: This embodiment provides a method for preparing iron-doped ruthenium dioxide acidic oxygen evolution electrocatalysts using a non-equilibrium salt template. The preparation process is shown in the attached figure. Figure 1 As shown, the specific steps include the following: (1) Place 0.19 mmol Ru(acac)3, 0.01 mmol Fe(acac)3, 80 mg NaCl and 120 mg LiCl in an agate mortar, mix and grind for 15 min to obtain a mixture of acetylacetone metal salt and salt template; (2) The catalyst precursor prepared in step (1) is calcined and oxidized in an air atmosphere, heated to 350 °C at a heating rate of 5 °C / min, and held at that temperature for 2 h to obtain FeRuO. x / NaCl / LiCl complex; (3) Immediately remove the calcined product FeRuO x The NaCl / LiCl complex was soaked in deionized water at room temperature for 5 minutes, followed by water quenching and rapid cooling to achieve rapid cooling. (4) Rapidly cool the FeRuO2 after step (3) x The NaCl / LiCl complex was acid-washed for 8 h using 0.1 mol / L dilute hydrochloric acid. FeRuO xThe ratio of the NaCl / LiCl complex to dilute hydrochloric acid is approximately 0.35 g: 20 mL, which allows the NaCl and LiCl salt templates to dissolve in the dilute hydrochloric acid solution. (5) The product after acid washing in step (4) is centrifuged three times at 4000 rpm for 5 min. It is then washed with deionized water until the pH of the washing solution is approximately 7. The product is then dried in an oven at 80 ℃ for 12 h to obtain the iron-doped ruthenium dioxide electrocatalyst, denoted as Fe. 0.05 Ru 0.95 O2-350.

[0066] Comparative Example 1 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the amount of Ru(acac)3 was replaced by 0.18 mmol and the amount of Fe(acac)3 was replaced by 0.02 mmol. The product is denoted as Fe. 0.1 Ru 0.9 O2-350.

[0067] Comparative Example 2 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the amount of Ru(acac)3 was replaced with 0.2 mmol and the amount of Fe(acac)3 was replaced with 0 mmol. The product was denoted as RuO2-350.

[0068] Comparative Example 3 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the amount of Ru(acac)3 was replaced by 0.16 mmol and the amount of Fe(acac)3 was replaced by 0.04 mmol. The product is denoted as Fe. 0.2 Ru 0.8 O2-350.

[0069] Comparative Example 4 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the amount of Ru(acac)3 was replaced by 0.14 mmol and the amount of Fe(acac)3 was replaced by 0.06 mmol. The product is denoted as Fe. 0.3 Ru 0.7 O2-350.

[0070] Comparative Example 5 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that step (3) is replaced by removing the calcined product FeRuO. xThe NaCl / LiCl complex was then allowed to cool naturally at room temperature, and the product was designated as Fe. 0.05 Ru 0.95 O2-350 was not water-quenched.

[0071] Comparative Example 6 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the calcination oxidation temperature was replaced with 300 °C, and the product was denoted as Fe. 0.05 Ru 0.95 O2-300.

[0072] Comparative Example 7 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the calcination oxidation temperature was replaced with 400 °C, and the product was denoted as Fe. 0.05 Ru 0.95 O2-400.

[0073] Comparative Example 8 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that 80 mg NaCl and 120 mg LiCl were replaced with 200 mg NaCl. The product is denoted as Fe. 0.05 Ru 0.95 O2-350NaCl.

[0074] Comparative Example 9 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that 80 mg NaCl and 120 mg LiCl were replaced with 200 mg LiCl. The product is denoted as Fe. 0.05 Ru 0.95 O2-350LiCl.

[0075] Comparative Example 10 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that 80 mg NaCl and 120 mg LiCl were replaced with 100 mg NaCl and 100 mg LiCl. The product is denoted as Fe. 0.05 Ru 0.95 O2-350 NaCl:LiCl=1:1.

[0076] Comparative Example 11 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the ruthenium acetylacetone content was changed to 0.38 mmol, the iron acetylacetone content was changed to 0.02 mmol, and the acid washing process time was changed to 6 h. The product is denoted as Fe. 0.05 Ru 0.95 Pickling at 350°C for 6 hours.

[0077] Comparative Example 12 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the ruthenium acetylacetone content was changed to 0.38 mmol and the iron acetylacetone content was changed to 0.02 mmol. The product is denoted as Fe. 0.05 Ru 0.95 Pickling at 350°C for 8 hours.

[0078] Comparative Example 13 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the ruthenium acetylacetone content was changed to 0.38 mmol, the iron acetylacetone content was changed to 0.02 mmol, and the acid washing process time was changed to 10 h. The product is denoted as Fe. 0.05 Ru 0.95 Pickling at O2-350 for 10 hours.

[0079] Comparative Example 14 Iron-doped ruthenium dioxide acidic oxygen evolution electrocatalyst was prepared according to the method of Example 1. The difference from Example 1 is that the 0.1 M HCl solution used in the acid washing process was replaced with 0.5 M HCl. The product is denoted as Fe. 0.05 Ru 0.95 O2-3500.5 M HCl.

[0080] Test case The working electrode for the chronopotentiometric (CP) assay used carbon paper containing catalyst ink, prepared as follows: 2.5 mg of the catalyst prepared in the examples or comparative examples, 400 μL of ethanol, and 30 μL of Nafion 117 solution were mixed in a 2 mL EP tube and sonicated for 1 h to prepare the catalyst ink. A 1 × 1 cm piece of carbon paper was cut, and a 0.5 × 1 cm portion was sealed. Then, 25 μL of catalyst ink was drop-coated onto one side of the unsealed carbon paper, repeated twice. The same operation was performed on the other side of the carbon paper. The catalyst loading of the carbon paper was 1 mg / cm³. 2 .

[0081] Except for the chronopotentiometric method, which used a two-electrode system, all electrochemical tests used a three-electrode system and were conducted using a Shanghai Chenhua CHI760f electrochemical workstation. The Hg / Hg₂SO₄ electrode served as the reference electrode, the Pt wire as the counter electrode, and the L-shaped glassy carbon electrode (GCE) coated with catalyst ink as the working electrode. A 0.5 M H₂SO₄ solution was used as the electrolyte. The electrode potentials were standardized using the Nernst equation and converted to a potential difference relative to the reversible hydrogen electrode (RHE). The calculation formula is: under acidic conditions, E(vs. RHE) = E(vs. Hg / Hg₂SO₄) + 0.059 pH + 0.652.

[0082] The working electrode was prepared as follows: 2.5 mg of the catalyst prepared in the examples or comparative examples, 400 μL of ethanol, and 30 μL of Nafion 117 solution were mixed in a 2 mL EP tube and sonicated for 1 h to prepare catalyst ink. Then, 5 μL of the catalyst ink was drop-coated onto the RDE surface, and rotary evaporation was performed at 200 rpm for 15 min. This process was repeated twice to prepare the working electrode, with a loading of approximately 0.3 mg / cm³. 2 .

[0083] The potentials described in the following tests can all be set on an electrochemical workstation, relative to the Hg / Hg2SO4 reference electrode.

[0084] Linear sweep voltammetry (LSV): The electrolyte was 0.5 M H₂SO₄ solution. Before LSV testing, at least 5 cycles of CV activation were performed. The CV settings were: initial potential 0 V, maximum potential 0.9 V, minimum potential 0 V, termination potential 0 V, scan rate 20 mV / s, and iR compensation 95%. Then, the LSV test was performed with the following settings: initial potential 0 V, termination potential 0.9 V, scan rate 5 mV / s, and iR compensation 95%.

[0085] Tafel curve: Through further analysis of the LSV curve, the Tafel curve (η = b·log j + a) can be constructed, where a and b represent the Tafel coefficients, and j indicates the current density. Figure 5 , Figure 9 j is 10 mA / cm 2 The Tafel slope value is 10 mA / cm. 2 The overpotential-current density data within the ±50 mV overpotential range were obtained by linear fitting.

[0086] Stability testing employed two methods: chronopotential bonding (CP) and LSV plots before and after 5000 cyclic voltammetry (CV). Specific operating conditions are as follows: Chronopotentiometric method (CP): Current density set at 10 mA / cm² 2 The cutoff potential is 1.35 V.

[0087] Cyclic voltammetry (CV): initial potential 0.5 V, highest potential 0.9 V, lowest potential 0.5 V, termination potential 0.5 V, scan rate 100 mV / s, 5000 scans.

[0088] Linear scanning voltammetry (LSV): initial potential 0.5 V, termination potential 0.9 V, scan rate 5 mV / s, iR compensation 95%.

[0089] The test results are as follows: The X-ray diffraction (XRD) patterns of the electrocatalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown below. Figure 2 As shown. From Figure 2 As can be seen, Fe doping results in a higher diffraction angle compared to the theoretical diffraction angle of RuO2 (PDF # 04-007-8843). 0.05 Ru 0.95 O2-350 and Fe 0.01 Ru 0.9 The O2-350 peak systematically shifts to a higher angle, and no diffraction peaks of other phases such as Fe2O3 appear, indicating that in the electrocatalysts with 5% and 10 at% Fe doping, Fe is uniformly doped into the RuO2 unit cell, forming a uniform solid solution. Figure 2 This indicates that Fe-doped RuO2 electrocatalysts were successfully prepared in Examples 1 and 1 of this application, and RuO2 electrocatalysts were successfully prepared in Comparative Example 2.

[0090] Transmission electron microscopy (TEM) image of the electrocatalyst prepared in Example 1 is shown below. Figure 3 As shown. From Figure 3 It can be seen that Fe 0.05 Ru 0.95 The TEM image at 100 nm magnification from O2-350 mainly shows staggered stacked spherical materials, which proves that the non-equilibrium salt template plays a confinement effect and helps to prepare high specific surface area porous catalysts.

[0091] The energy dispersive X-ray spectroscopy (EDX) analysis of the electrocatalyst prepared in Example 1 is shown in the figure below. Figure 4 As shown. Among them, Figure 4 (a) is a map showing the distribution of oxygen. Figure 4 (b) is a distribution map of ruthenium. Figure 4(c) is a diagram showing the iron element distribution. It can be seen that the electrocatalyst prepared in Example 1 achieves Fe doping with RuO2 while Na and Li remain undoped with RuO2. In this invention, the type of salt template cannot be arbitrarily changed, otherwise co-doping will occur.

[0092] Table 1. Overpotentials and Tafel slopes of Example 1 and Comparative Examples 1-14

[0093] The linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in 0.5 M H₂SO₄ electrolyte for Examples 1 and 4 are shown below. Figure 5 As shown. From Figure 5 It can be seen from this that at 10 mA / cm 2 Fe prepared in Example 1 at current density 0.05 Ru 0.95 The overpotential required for O2-350 is only 184 mV; lower than that for RuO2-350. This is the Fe prepared in Example 1. 0.05 Ru 0.95 O2-350 has the lowest overpotential, requiring the least additional "driving force" to reach the same current density, and exhibits the highest electrocatalytic activity.

[0094] Tafel curves of the electrocatalysts prepared in Examples 1 and 4 in 0.5 M H2SO4 electrolyte are shown below. Figure 6 As shown. From Figure 6 As can be seen from the data, the Fe prepared in Example 1 0.05 Ru 0.95 The O2-350 catalyst exhibits the smallest Tafel slope at 56.24 mV / dec, while the electrocatalysts prepared in Comparative Examples 1-4 show larger Tafel slopes of 58.78 mV / dec, 70.10 mV / dec, 66.64 mV / dec, and 94.86 mV / dec, respectively. This demonstrates that the electrocatalyst prepared in Example 1 possesses an excellent Tafel slope, with a faster increase in current density and intrinsic reaction kinetics as the overpotential increases.

[0095] Comparison of LSV curves of the electrocatalyst prepared in Example 1 before and after 5000 cyclic voltammetry (CV) tests in 0.5 M H2SO4 electrolyte. Figure 7 As shown. Among them, Fe 0.05 Ru 0.95 O2before is the LSV curve before 5000 cycles of cyclic voltammetry testing; Fe 0.05 Ru 0.95 O2after is the LSV curve after 5000 cycles of cyclic voltammetry testing. From Figure 7As can be seen from this, after 5000 cycles, at 10 mA / cm 2 At current density, the overpotential increment is only 21 mV, indicating that its performance degradation is within an acceptable range and its stability is good.

[0096] The constant current (CP) stability test graph of the electrocatalyst prepared in Example 1 in 0.5 M H2SO4 electrolyte is shown in the figure below. Figure 8 As shown. From Figure 8 As can be seen, the curve is generally a stable horizontal line, and the potential hardly changes with time. This electrocatalyst operates at 10 mA / cm². 2 It can operate stably for more than 180 hours at current density. Figure 7 and Figure 8 All of these results demonstrate that Example 1 possesses good catalytic stability.

[0097] The linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in Example 1 and Comparative Example 5 in 0.5 M H2SO4 electrolyte are shown below. Figure 9 As shown. From Figure 9 It can be seen that, compared with Example 1 which was water-quenched, the electrocatalyst prepared in Comparative Example 5 which was not water-quenched has a lower efficiency at 10 mA / cm². 2 The overpotential at the current density was 195 mV, an increase of 11 mV compared to the water-quenched example, requiring more additional "driving force" to achieve the same current density as in Example 1. This indicates that the water quenching step can reduce the OER reaction overpotential and improve the catalytic activity of the electrocatalyst.

[0098] The Tafel curves of the electrocatalysts prepared in Example 1 and Comparative Example 5 in 0.5 M H2SO4 electrolyte are shown below. Figure 10 As shown. From Figure 10 As can be seen from this, the electrocatalyst prepared in Comparative Example 5 without water quenching exhibits a performance of 10 mA / cm². 2 The Tafel slope at the current density was 65.37 mV / dec, which was 16.2% higher than that of Example 1 after water quenching. This indicates that the absence of the water quenching step caused the current density to rise more slowly with increasing overpotential, thus slowing down the intrinsic kinetics of the reaction.

[0099] The LSV curves of the electrocatalysts prepared in Example 1 and Comparative Example 6 in 0.5 M H2SO4 electrolyte at different times are shown in the figure. Figure 11 As shown. From Figure 11 It can be seen that Comparative Example 6 (Fe) calcined at 300℃ 0.05 Ru 0.95In Example 6 (O2-300), the overpotential of the first LSV was 174 mV, and the overpotential of the third LSV was 186 mV, a difference of 12 mV. In Example 1, the overpotential of the first LSV was 184 mV, and the overpotential of the third LSV was 186 mV, a difference of 2 mV, which is within the normal measurement error range. It is evident that excessively low calcination temperature leads to decreased stability of the electrocatalyst, with Comparative Example 6 exhibiting worse stability than Example 1.

[0100] The linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in Example 1 and Comparative Example 7 in 0.5 M H2SO4 electrolyte are shown in the figure below. Figure 12 As shown. From Figure 12 It can be seen from this that at 10 mA / cm 2 Fe prepared in Example 1 at current density 0.05 Ru 0.95 The overpotential required for O2-350 is only 184 mV; lower than that of Comparative Example 7 Fe. 0.05 Ru 0.95 O2-400. It is evident that excessively high calcination temperature leads to an increase in the overpotential of the electrocatalyst. That is, the Fe prepared in Example 1... 0.05 Ru 0.95 O2-350 has the lowest overpotential, requiring the least additional "driving force" to reach the same current density, and exhibits the highest electrocatalytic activity.

[0101] The linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in Example 1 and Comparative Examples 8-10 in 0.5 M H2SO4 electrolyte are shown below. Figure 13 As shown. From Figure 13 It can be seen from this that at 10 mA / cm 2 Fe prepared in Example 1 at current density 0.05 Ru 0.95 The overpotential required for O2-350 is only 184 mV, lower than that of comparative examples prepared with different salt template ratios (8-10). This demonstrates that FeRuO generated using a single salt template and a 1:1 mass ratio of sodium chloride to lithium chloride... x The catalytic activity of the catalysts was not as good as that of FeRuO generated from sodium chloride and lithium chloride with a salt template mass ratio of 2:3. x The catalytic activity of the catalyst. Specifically, the Fe prepared in Example 1. 0.05 Ru 0.95 O2-350 has the lowest overpotential, requiring the least additional "driving force" to reach the same current density, and exhibits the highest electrocatalytic activity.

[0102] The linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in Comparative Examples 11-13 in 0.5 M H₂SO₄ electrolyte are shown in the figure below. Figure 14 As shown. From Figure 14 It can be seen from this that at 10 mA / cm 2 Fe prepared in Comparative Example 12 at current density 0.05 Ru 0.95 The overpotential required for 8 hours of pickling with O2-350 was 218 mV, lower than that of Comparative Examples 11 and 13 with different pickling times. This indicates that 8 hours is the optimal pickling time; too high or too low a pickling time will lead to an increase in the overpotential. This is similar to the Fe prepared in Comparative Example 12. 0.05 Ru 0.95 O2-3508h possesses the lowest overpotential, requiring the least additional "driving force" to reach the same current density, and exhibits the highest electrocatalytic activity. Note: Figure 14 The difference between the test process and the experimental case is that the iR resistor compensation was not performed in the LSV test process.

[0103] The linear sweep voltammetry (LSV) curves of the electrocatalysts prepared in Example 1 and Comparative Example 14 in 0.5 M H2SO4 electrolyte are shown below. Figure 15 As shown. From Figure 15 It can be seen from this that at 10 mA / cm 2 Fe prepared in Example 1 at current density 0.05 Ru 0.95 The overpotential required for O2-350 is only 184 mV; lower than that of Comparative Example 14 Fe. 0.05 Ru 0.95 O2-350 0.5 M HCl. This refers to the Fe prepared in Example 1. 0.05 Ru 0.95 O2-350 has the lowest overpotential, requiring the least additional "driving force" to reach the same current density, and exhibits the highest electrocatalytic activity.

[0104] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present 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 them. Any modifications, equivalent substitutions, improvements, 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 iron-doped ruthenium dioxide electrocatalyst, characterized in that, Includes the following steps: Ruthenium acetylacetonate, iron acetylacetonate, sodium chloride, and lithium chloride were mixed and ground to obtain a catalyst precursor. The catalyst precursor was calcined to obtain FeRuO x / NaCl / LiCl complex; The FeRuO2 was subjected to water quenching and rapid cooling. x / NaCl / LiCl complex, to obtain cooled FeRuO x / NaCl / LiCl complex; FeRuO after pickling and cooling x The NaCl / LiCl complex was centrifuged, washed with water, and dried to obtain the iron-doped ruthenium dioxide electrocatalyst.

2. The method for preparing the iron-doped ruthenium dioxide electrocatalyst as described in claim 1, characterized in that, The total amount of ruthenium acetylacetonate and iron acetylacetonate is in a mass ratio of 0.2-0.3 mmol to 200 mg of sodium chloride and lithium chloride; the molar ratio of ruthenium acetylacetonate to iron acetylacetonate is 9-19:

1. Preferably, the total amount of ruthenium acetylacetonate and iron acetylacetonate is in a mass ratio of 0.2 mmol to 200 mg of sodium chloride and lithium chloride; and the molar ratio of ruthenium acetylacetonate to iron acetylacetonate is 19:

1.

3. The method for preparing the iron-doped ruthenium dioxide electrocatalyst as described in claim 1, characterized in that, The mass ratio of sodium chloride to lithium chloride is 2:2.5-3.5; Preferably, the mass ratio of sodium chloride to lithium chloride is 2:

3.

4. The method for preparing the iron-doped ruthenium dioxide electrocatalyst as described in claim 1, characterized in that, The calcination process includes: heating to 340-450 ℃ at a heating rate of 4-6 ℃ / min and holding at that temperature for 1.5-2.5 h.

5. The method for preparing the iron-doped ruthenium dioxide electrocatalyst as described in claim 1, characterized in that, The steps of the water quenching and rapid cooling treatment include: soaking in water at room temperature for 4-6 minutes.

6. The method for preparing the iron-doped ruthenium dioxide electrocatalyst as described in claim 1, characterized in that, Immediately remove the calcined FeRuO x The NaCl / LiCl complex was subjected to water quenching and rapid cooling.

7. The method for preparing the iron-doped ruthenium dioxide electrocatalyst as described in claim 1, characterized in that, The pickling process includes: using dilute hydrochloric acid to treat the cooled FeRuO₂. x The NaCl / LiCl complex was acid-washed for 2-12 h with a dilute hydrochloric acid concentration of 0.1-0.3 mol / L. FeRuO x The ratio of the NaCl / LiCl complex to dilute hydrochloric acid is approximately 0.35 g: 20 mL.

8. The method for preparing the iron-doped ruthenium dioxide electrocatalyst as described in claim 1, characterized in that, The washing process includes washing with water until the pH of the washing solution is 6-8.

9. An iron-doped ruthenium dioxide electrocatalyst prepared by the preparation method according to any one of claims 1-8.

10. The application of the iron-doped ruthenium dioxide electrocatalyst of claim 9 in the electrocatalytic oxygen evolution reaction in acidic media.

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