Preparation method and application of a defective ruthenium dioxide aerogel catalyst

Abstract

The application discloses a preparation method and application of a defect-rich ruthenium dioxide aerogel catalyst, and the preparation method comprises the following steps: S1: uniformly mixing a ruthenium source, a selenium source and water to obtain a solution A, uniformly mixing a reducing agent and water to obtain a solution B, and adding the solution A into the solution B, and then washing after reaction to obtain Ru2Se AS; S2: loading the Ru2Se AS obtained in the step S1 on carbon black, and then performing washing and freeze-drying to obtain Ru2Se aerogel loaded on the carbon black; and S3: performing heat treatment on the Ru2Se aerogel loaded on the carbon black obtained in the step S2 to obtain a product. Electrochemical tests show that the prepared defect-rich ruthenium dioxide aerogel catalyst has high water electrolysis oxygen evolution (OER) performance under an acidic condition, and has good application prospect and commercialization potential.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic water splitting, specifically relating to a method for preparing and applying a defect-rich ruthenium dioxide aerogel catalyst. Background Technology

[0002] Since the beginning of the 21st century, the massive consumption of fossil fuels and the resulting energy and environmental problems have received increasing attention. Developing green and sustainable new energy sources to replace increasingly depleted traditional fossil fuels has gradually become a global consensus. Therefore, finding new, efficient, and environmentally friendly energy sources is a crucial way to solve the energy crisis. Various sustainable energy sources in nature, such as solar, wind, and tidal energy, are typically intermittent, making them difficult to directly apply to human production and daily life. Therefore, developing efficient energy conversion and storage technologies is of great significance for the development and utilization of sustainable energy. Among numerous clean energy sources, hydrogen energy, as an ideal secondary energy source, possesses many advantages such as high energy density, clean and pollution-free combustion products, and abundant sources, and is considered the best energy carrier to replace fossil fuels. Currently, hydrogen is mainly produced from fossil fuels (coal, oil, natural gas, etc.) through reforming reactions. However, this method consumes fossil fuels and emits large amounts of greenhouse gases, thus failing to fundamentally solve the energy and environmental problems. In contrast, water electrolysis, which directly converts water into hydrogen and oxygen, offers a more ideal hydrogen production pathway. The hydrogen evolution reaction (HER) occurs at the cathode, while the oxygen evolution reaction (OER) occurs at the anode. The OER is a four-electron transfer process, and its sluggish kinetics make it a bottleneck in water electrolysis, resulting in low hydrogen production efficiency and high energy consumption. Therefore, it is necessary to develop highly active OER catalysts to reduce the energy consumption of this reaction, thus enabling the large-scale practical application of electrochemical water splitting. Acidic OER catalysts are mainly Ru-based and Ir-based materials, with Ru-based nanomaterials typically exhibiting high catalytic activity and thus attracting considerable attention from researchers. However, RuO2 is prone to electrochemical dissolution under high-potential operating conditions, exhibiting poor stability.

[0003] Currently, research on noble metals modified with defects based on aerogels is not yet complete. Designing and developing a method for preparing a defect-rich ruthenium dioxide aerogel catalyst and its application in oxygen evolution is of great significance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a method for preparing and applying a defect-rich ruthenium dioxide aerogel catalyst.

[0005] The first aspect of this invention is to provide a method for preparing a defect-rich ruthenium dioxide aerogel catalyst, comprising the following steps:

[0006] S1: Mix ruthenium source, selenium source and water evenly to obtain solution A; mix reducing agent with water evenly to obtain solution B; add solution A to solution B; wash after reaction to obtain Ru2Se AS;

[0007] S2: The Ru2Se AS obtained in step S1 is loaded onto carbon black, and after washing and freeze-drying, Ru2Se aerogel (Ru2Se AS) loaded on carbon black is obtained.

[0008] S3: Heat-treat the Ru2Se aerogel loaded on carbon black obtained in step S2 to obtain the product (Se-RuO2AS).

[0009] Preferably, in step S1, the ruthenium source is a Ru element precursor, and the selenium source is a Se element precursor.

[0010] Preferably, the ruthenium source is ruthenium trichloride.

[0011] Preferably, the selenium source is selenite.

[0012] Preferably, the reducing agent is sodium borohydride.

[0013] Preferably, in step S2, the Ru2Se AS and carbon black are dispersed in ethanol and ultrasonically homogenized, then mixed together, centrifuged, and freeze-dried, so that Ru2Se AS is loaded onto the carbon black.

[0014] Preferably, in step S2, the carbon black is Vulcan XC72R carbon.

[0015] Preferably, in step S2, the freeze-drying temperature is -20~-70℃, the pressure is less than 1MPa, and the freeze-drying time is 20-28h.

[0016] Preferably, in step S3, the heat treatment method is calcination, the calcination temperature is 200~400℃, the calcination time is 12~18h, and the calcination atmosphere is air.

[0017] A second aspect of the present invention is to provide an application of a defect-rich ruthenium dioxide aerogel catalyst prepared by the preparation method described above in the electrocatalytic water cracking for oxygen release.

[0018] The beneficial effects of this invention are as follows:

[0019] This invention uses ruthenium trichloride and selenite as precursors to obtain Ru2Se aerogel by reduction with sodium borohydride. After being loaded onto carbon, the aerogel is combined with a subsequent heat treatment process to form abundant grain boundaries and lattice distortion, resulting in Ru-based nanomaterials rich in defects.

[0020] The surface area of ​​Se-RuO2AS is almost 20 times that of commercial RuO2. This increased surface area generally contributes to improved catalytic activity. Simultaneously, the presence of both mesoporous and macroporous structures promotes high dispersion of catalyst species and effectively prevents excessive growth of intermediates on the catalyst surface, thereby stabilizing exposed active sites. Under 0.5 M H2SO4, Se-RuO2AS exhibits high catalytic activity at 10 mAcm⁻¹. -2 The overpotential of Se-RuO2AS is 169 mV, which is superior to that of commercial RuO2 (300 mV). Simultaneously, the stability of Se-RuO2AS under acidic conditions is also superior to that of commercial RuO2, with a stability of 10 mA cm⁻¹ in 0.5 M H₂SO₄. -2 The stability at the current density is 48 hours. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0022] Figure 1 This is a schematic diagram of transmission electron microscopy (TEM) images of Ru2Se AS prepared in Example 1 of the present invention at different magnifications, showing the aerogel structure of Ru2Se AS;

[0023] Figure 2 This is a schematic diagram of a transmission electron microscope (TEM) image of the Se-RuO2AS catalyst prepared in Example 1 of this invention. The image shows that the cross-network structure of Se-RuO2AS includes many small crystallites, which easily generate a large number of defects, thus improving catalytic performance.

[0024] Figure 3 This is a schematic diagram of a high-resolution transmission electron microscope (HRTEM) image of the Se-RuO2AS catalyst prepared in Example 1 of the present invention. The image clearly shows defects, including amorphous defects (blue area), lattice knots (yellow dashed lines), and lattice boundaries (red dashed lines).

[0025] Figure 4 This is a schematic diagram of scanning electron microscope (SEM) and scanning electron microscope energy dispersive spectroscopy (SEM-EDS) images of the Ru2Se AS electrocatalyst material prepared in Example 1 of this invention, showing the porous structure of the Ru2Se AS catalyst. According to the SEM-EDS determination, the atomic ratio of Ru / Se is approximately 64.1:35.9;

[0026] Figure 5This is a schematic diagram of the X-ray diffraction (XRD) and scanning electron microscopy (SEM-EDS) spectra of the Se-RuO2AS electrocatalytic material prepared in Example 1 of this invention, showing that all diffraction peaks of the catalyst correspond to the rutile structure of RuO2 (PDF#88-0322). According to the SEM-EDS determination, the atomic ratio of Ru / Se is approximately 88.1:11.9;

[0027] Figure 6 This is a schematic diagram of the energy dispersive spectroscopy (EDS) of the Se-RuO2AS electrocatalytic material prepared in Example 1 of the present invention, showing the uniform distribution of Ru, Se and O in the catalyst;

[0028] Figure 7 This is a schematic diagram of the OER polarization curves (a) and Tafel slope diagram (b) of Se-RuO2AS, RuO2AS and Pt / C prepared in Example 1 of this invention. Se-RuO2AS exhibits extremely high electrocatalytic activity at 10 mA cm⁻¹. −2 The overpotential under these conditions was only 166 mV, exceeding that of RuO2AS (210 mV) and commercial RuO2 (330 mV). Furthermore, the Tafel slope plot of Se-RuO2AS showed a lower Tafel slope of 41.0 mV dec−1, which is superior to RuO2AS (48.1 mV dec−1). –1 ) and commercial RuO2 (73.0 mV dec −1 This means that Se-RuO2AS has stronger OER kinetics;

[0029] Figure 8 The Se-RuO2AS prepared in Example 1 of this invention is in 0.5 M H2SO4 solution at 10 mA cm⁻¹ -2 A schematic diagram of the stability curve of oxygen desorption in water cracking shows that Se-RuO2AS retained most of its cracking potential within 48 hours, while the activity of RuO2AS and commercial RuO2 decreased significantly. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] Example 1

[0032] S1. Preparation of Ru2Se AS

[0033] 10.37 mg of ruthenium trichloride, 3.23 mg of selenite, and 1 ml of deionized water were mixed and then sonicated to form a homogeneous solution A. 10.41 mg of sodium borohydride was mixed with 5 ml of deionized water to form a freshly prepared homogeneous solution B. Finally, solution A was added to solution B, and the mixture was reacted at room temperature for 4 hours. The solution was then washed 6 times with ultrapure water to obtain Ru₂Se₄.

[0034] S2. Preparation of Se-RuO2AS

[0035] The Ru2Se AS obtained in step S1 and the carbon black were dispersed evenly with ethanol, then mixed together, centrifuged, and freeze-dried for 24 hours to load Ru2Se AS onto the carbon black. The dried product was then calcined at 300°C for 15 hours in air to finally obtain a defect-rich ruthenium dioxide aerogel catalyst (Se-RuO2AS).

[0036] Application examples

[0037] A three-electrode system was used to test the performance of the Se-RuO2AS electrocatalytic material obtained in Example 1 for electrocatalytic water cracking and oxygen release (OER). The specific processing method was as follows: Se-RuO2AS was used as the working electrode, carbon rod as the counter electrode, and calomel electrode as the reference electrode. Linear voltammetric scanning tests were performed in 0.5M H2SO4 electrolyte to evaluate the OER performance.

[0038] The samples used were Se-RuO2AS, RuO2AS prepared in Example 1 of this invention, and commercial RuO2, respectively. Figure 7 As can be seen, Se-RuO2AS has the best performance, outperforming commercial RuO2.

[0039] This demonstrates that the Se-RuO2AS electrocatalytic material described in this invention has excellent water electrolysis performance and can be used in the field of electrocatalytic acidic OER.

[0040] The applicant declares that the above-disclosed technical solutions are merely preferred embodiments of the present invention and should not be considered as limitations on the scope of the present invention. Therefore, all equivalent variations made by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

[0041] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a defect-rich ruthenium dioxide aerogel catalyst, characterized in that, Includes the following steps: S1: Ruthenium source, selenium source and water are mixed evenly to obtain solution A. Reducing agent is mixed evenly with water to obtain solution B. Solution A is added to solution B. After reaction and washing, Ru2Se aerogel is obtained. S2: The Ru2Se aerogel obtained in step S1 is loaded onto carbon black, and after washing and freeze-drying, Ru2Se aerogel loaded on carbon black is obtained. S3: Heat-treat the Ru2Se aerogel loaded on carbon black obtained in step S2 to obtain the product.

2. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 1, characterized in that: In step S1, the ruthenium source is a Ru precursor and the selenium source is a Se precursor.

3. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 2, characterized in that: The ruthenium source is ruthenium trichloride.

4. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 2, characterized in that: The selenium source is selenite.

5. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 1, characterized in that: The reducing agent is sodium borohydride.

6. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 1, characterized in that: In step S2, the Ru2Se aerogel and carbon black are dispersed separately with ethanol, ultrasonicated and homogenized, and then mixed together, centrifuged and freeze-dried, so that the Ru2Se aerogel is loaded onto the carbon black.

7. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 1, characterized in that: In step S2, the carbon black is Vulcan XC72R carbon.

8. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 1, characterized in that: In step S2, the freeze-drying temperature is -20~-70℃, the pressure is less than 1MPa, and the freeze-drying time is 20-28h.

9. The method for preparing a defect-rich ruthenium dioxide aerogel catalyst according to claim 1, characterized in that: In step S3, the heat treatment method is calcination, the calcination temperature is 200~400℃, the calcination time is 12~18h, and the calcination atmosphere is air.

10. The application of the defect-rich ruthenium dioxide aerogel catalyst prepared by the preparation method according to any one of claims 1-9 in the electrocatalytic water cracking for oxygen release.

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