Chromium and samarium monatomic doped catalyst as well as preparation method and application thereof

Abstract

The invention provides a chromium and samarium monatomic doped ruthenium oxide catalyst and a preparation method and application thereof, and solves the problem that the long-period stability of an existing ruthenium-based catalyst still cannot meet the performance requirement of a commercial PEM system for an acidic OER catalyst.The preparation method comprises the steps that S1, a mixed solution is fully heated and stirred for a reaction, and a solid mixture is obtained; the mixed solution comprises ruthenium salt, chromium salt, samarium salt, a chelating agent, a pH regulator and a template agent; and S2, roasting the solid mixture, and cooling to obtain the catalyst. The ruthenium salt is selected from one or more of ruthenium acetate, ruthenium nitrate and ruthenium chloride; the chromium salt is selected from at least one of chromium sulfate, chromium chloride and chromium nitrate; the samarium salt is selected from at least one of samarium nitrate, samarium sulfate, samarium chloride and samarium acetate; the chelating agent is tannic acid; the pH regulator and the template agent are urea.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a catalyst doped with single chromium and samarium atoms, and a preparation method and application thereof. Background Art

[0002] Hydrogen, an environmentally friendly, high-calorific-value gaseous fuel, is an ideal energy storage medium for renewable energy and one of the most important future alternatives to fossil fuels. Among the many hydrogen production methods, water electrolysis using renewable electricity (such as solar and wind power) has attracted widespread attention due to its environmental friendliness and sustainability. Among these, proton exchange membrane water electrolysis (PEMWE) systems are considered one of the most efficient devices for producing green hydrogen due to their lightweight and compact design, high hydrogen purity, high energy conversion efficiency, and rapid adaptability to load changes. However, the high cost of iridium-based catalysts in PEMWE systems is a key bottleneck restricting their large-scale application. Currently, iridium and its oxides (such as IrO2) are recognized as the most reliable oxygen evolution (OER) catalysts that operate stably in acidic environments. However, their scarcity and high price (approximately five times that of gold) contribute to the high cost of PEM systems. In recent years, many research teams at home and abroad have been committed to developing low-cost alternatives to iridium-based catalysts, with the most popular focus being on modifying highly active and low-cost ruthenium-based catalysts. Researchers can manipulate ruthenium-based catalysts through methods such as component structure and electronic structure manipulation to overcome their shortcomings of degradation and deactivation under acidic conditions. Although some research has been successful, the long-term stability of these materials under industrial-grade high-current conditions still cannot meet the performance requirements of acidic OER catalysts for commercial PEM systems. Therefore, the development of low-cost Ru-based acidic OER catalysts with both high activity and high stability remains a significant and meaningful challenge. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the existing technology. The present invention proposes a catalyst doped with single atoms of chromium and samarium and its preparation method and application to solve the problems related to low activity and poor stability of existing acidic OER catalysts. The present invention develops a ruthenium-based catalyst doped with single atoms of chromium and samarium through a carrier confinement strategy. Studies have shown that its catalytic oxygen evolution mechanism is transformed from the traditional AEM pathway to a three-site synergistic oxygen-oxygen coupling pathway, thereby promoting the kinetic process of OER and improving the intrinsic activity of the catalyst. -2 The electrolysis voltage is only 1.580V. At the same time, the catalyst also has a very robust structure. -2 It can operate stably for 850 hours under the electrical density of 10000V, fully demonstrating its value in industrial applications.

[0004] To solve the above technical problems, the present invention adopts a technical solution: a method for preparing a ruthenium oxide catalyst doped with single atoms of chromium and samarium, comprising the following steps:

[0005] S1. Fully heating and stirring the mixed solution to obtain a solid mixture, wherein the mixed solution includes a ruthenium salt, a chromium salt, a samarium salt, a chelating agent, a pH adjuster, and a template agent;

[0006] S2. calcining the solid mixture and cooling it to obtain a catalyst.

[0007] Furthermore, in step S1,

[0008] The ruthenium salt is selected from one or more of ruthenium acetate, ruthenium nitrate and ruthenium chloride;

[0009] The chromium salt is selected from at least one of chromium sulfate, chromium chloride, and chromium nitrate;

[0010] The samarium salt is selected from at least one of samarium nitrate, samarium sulfate, samarium chloride, and samarium acetate;

[0011] The chelating agent is tannic acid;

[0012] The pH regulator and template agent are urea.

[0013] Furthermore, the molar ratio of ruthenium salt, chromium salt and samarium salt in the mixed solution is (1-20):(0.5-1.5):1; preferably the molar ratio is (4-10):1; the mass ratio of the tannic acid amount to the ruthenium salt is (1-30):1, and the mass ratio of the urea amount to the ruthenium salt is (10-50):1, preferably the mass ratio is (20-25):1.

[0014] Furthermore, the stirring reaction temperature is 140-160 degrees, and the stirring reaction time is 5-200 minutes.

[0015] Furthermore, in step S2, the calcination atmosphere is air, the calcination temperature is 300-1000° C., preferably 400-500° C., the calcination time is 2-10 h, and the catalyst is obtained after natural cooling.

[0016] A catalyst doped with single atoms of chromium and samarium is obtained by any of the above-mentioned preparation methods.

[0017] Furthermore, the catalyst-corresponding nanomaterial interface is composed of a multi-component metal oxide containing three elements: ruthenium, chromium, and samarium.

[0018] The use of the chromium and samarium single-atom doped catalyst as an anode material for acidic water electrolysis.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The ruthenium-based catalyst doped with chromium and samarium single atoms of the present invention, the coordination and dispersion effect of the chelating agent effectively inhibits the sintering and agglomeration of the chromium, samarium and ruthenium components, regulates the nanometer size of the ruthenium oxide doped with chromium and samarium, and realizes the effective synthesis of highly crystalline nanosheets; the use of pH regulator and template agent can make the mixture precursor of chromium, samarium and ruthenium salt form a loose multi-level porous structure during the roasting process, thereby significantly increasing the specific surface area of the material and improving its catalytic performance.

[0021] (2) The ruthenium-based catalyst doped with chromium and samarium in the present invention further introduces the dopant samarium (Sm) into the existing Cr-doped ruthenium dioxide (Cr-RuO2) system, which has been widely proven to improve the activity and stability of the catalyst. This realizes the transformation of the OER reaction pathway from the single-site AEM pathway of Cr0.05Ru0.95O2 to the three-site synergistic oxygen-oxygen coupling mechanism of Cr0.05Sm0.05Ru0.90O2, providing a new method for designing three-site synergistic oxygen-oxygen coupling OER catalysts.

[0022] (3) The ruthenium-based catalyst doped with chromium and samarium in the present invention exhibits outstanding activity and stability as a high-performance acidic oxygen evolution reaction electrocatalyst, with acidic OER performance surpassing most reported advanced catalysts. It can be used as an anode catalyst material for hydrogen production from water electrolysis in proton exchange membrane water electrolysis electrolyzers, addressing the high cost of existing industrial acidic oxygen evolution catalysts (primarily iridium-based catalysts). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them:

[0024] Figure 1 Shown is a comparison of the XRD patterns of the control group catalyst samples RuO2, Cr-RuO2 and the experimental group catalyst sample Sm-Cr-RuO2 in Example 1;

[0025] Figure 2 Shown are scanning electron microscope images of the catalyst samples described in Example 2, wherein (a) is an electron microscope image of the control group catalyst sample Cr-RuO2, and (b) is an electron microscope image of the experimental group catalyst sample Sm-Cr-RuO2;

[0026] Figure 3 Shown are transmission electron microscopy images (a, b) and particle size distribution diagram (c) of the Sm-Cr-RuO2 catalyst described in Example 3;

[0027] Figure 4Shown are electrochemical analyses of the control group catalyst samples Cr-RuO2, RuO2 and the experimental group catalyst sample Sm-Cr-RuO2 described in Example 4, wherein (a) is a comparison of electrochemical impedance spectroscopy (EIS) and (b) is a comparison of Tafel slopes;

[0028] Figure 5 Shown is a performance comparison diagram of oxygen evolution polarization curves of the control group catalyst sample RuO2 and the experimental group catalyst sample Sm-Cr-RuO2 described in Example 5;

[0029] Figure 6 The stability test results of the catalyst sample Sm-Cr-RuO2 in the experimental group described in Example 5 are shown in Figure (a), where Sm-Cr-RuO2 is used as the working electrode in a three-electrode system at 100 mA cm -2 The chronopotentiometry curve under the current density is shown in Figure (b). The water electrolysis system formed after the catalyst is made into a membrane electrode is at 1Acm -2 Discharge curve under electric density. DETAILED DESCRIPTION

[0030] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0031] Regarding the overall preparation steps, a method for preparing a ruthenium oxide catalyst doped with single atoms of chromium and samarium comprises the following steps:

[0032] S1. Fully heating and stirring the mixed solution to obtain a solid mixture, wherein the mixed solution includes a ruthenium salt, a chromium salt, a samarium salt, a chelating agent, a pH adjuster, and a template agent;

[0033] S2. calcining the solid mixture and cooling it to obtain a catalyst.

[0034] The following is a further description of the detailed preparation process in conjunction with a number of examples:

[0035] Example 1

[0036] 250 μL of 200 mg / mL RuCl3 solution, 100 μL of 50 mg mL -1 Cr(NO3)3·9H2O solution, 110 μL 50 mg mL -1A quartz tube was filled with a 100% Sm(NO₃)₃·6H₂O solution, 1 g of urea, and 0.2 g of tannic acid and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 6 hours to obtain the experimental catalyst sample Sm-Cr-RuO₂, designated as Example 1.

[0037] Example 2

[0038] 250 μL of 200 mg / mL RuCl3 solution, 100 μL of 50 mg mL -1 Cr(NO3)3·9H2O solution, 110 μL 50 mg mL -1 A quartz tube was filled with a 100% Sm(NO₃)₃·6H₂O solution, 1 g of urea, and 0.2 g of tannic acid and stirred thoroughly. The mixture was heated and stirred at 160°C for 20 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 400°C for 6 hours to obtain the experimental catalyst sample Sm-Cr-RuO₂, designated as Example Sample 2.

[0039] Example 3

[0040] 250 μL of 200 mg / mL RuCl3 solution, 100 μL of 50 mg mL -1 Cr(NO3)3·9H2O solution, 110 μL 50 mg mL -1 A quartz tube was filled with a 100% Sm(NO₃)₃·6H₂O solution, 1 g of urea, and 0.2 g of tannic acid and stirred thoroughly. The mixture was heated and stirred at 140°C for 20 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 500°C for 6 hours to obtain the experimental catalyst sample Sm-Cr-RuO₂, designated as Example 3.

[0041] Example 4

[0042] 250 μL of 200 mg / mL RuCl3 solution, 100 μL of 50 mg mL -1 Cr(NO3)3·9H2O solution, 110 μL 50 mg mL -1 A quartz tube was filled with a 100% Sm(NO₃)₃·6H₂O solution, 1 g of urea, and 0.2 g of tannic acid and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 10 hours to obtain the experimental catalyst sample Sm-Cr-RuO₂, designated as Example Sample 4.

[0043] Example 5

[0044] 300 μL of 200 mg / mL RuCl3 solution, 100 μL of 50 mg mL -1 Cr(NO3)3·9H2O solution, 110 μL 50 mg mL -1 A quartz tube was filled with a 1.2g Sm(NO₃)₃·6H₂O solution, 1.2g urea, and 0.4g tannic acid and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 6 hours to obtain the experimental catalyst sample Sm-Cr-RuO₂ Example 5.

[0045] Comparative Example 1

[0046] 250 μL of a 200 mg / mL RuCl₃ solution, 1 g of urea, and 0.2 g of tannic acid were added to a quartz tube and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 6 hours to obtain the control catalyst sample, RuO₂ Comparative Example 1.

[0047] Comparative Example 2

[0048] 250 μL of 200 mg / mL RuCl3 solution, 100 μL of 50 mg mL -1 A Cr(NO₃)₃·9H₂O solution, 1g of urea, and 0.2g of tannic acid were added to a quartz tube and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 6 hours to obtain the control catalyst sample, Cr-RuO₂ Comparative Example 2.

[0049] Comparative Example 3

[0050] 250 μL of a 200 mg / mL RuCl₃ solution, 1 g of urea, and 0.2 g of tannic acid were added to a quartz tube and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 10 hours to obtain the control catalyst sample, Cr-RuO₂ Comparative Example 3.

[0051] Comparative Example 4

[0052] 250 μL of 200 mg / mL RuCl3 solution, 100 μL of 50 mg mL -1A Cr(NO₃)₃·9H₂O solution, 1g of urea, and 0.2g of tannic acid were added to a quartz tube and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 10 hours to obtain the control catalyst sample, Cr-RuO₂ Comparative Example 4.

[0053] Comparative Example 5

[0054] 300 μL of a 200 mg / mL RuCl₃ solution, 1.2 g of urea, and 0.4 g of tannic acid were added to a quartz tube and stirred thoroughly. The mixture was heated and stirred at 150°C for 10 minutes. The resulting solid mixture was transferred to a muffle furnace and calcined in air at 450°C for 6 hours to obtain the control catalyst sample, RuO₂ Comparative Example 5.

[0055] The catalyst samples RuO2 and Cr-RuO2 of the control group and the catalyst sample Sm-Cr-RuO2 of the experimental group obtained in Example 1 and Comparative Examples 1-2 were subjected to X-ray diffraction test. The results are shown in FIG. Figure 1 As can be seen in the figure, the powder X-ray diffraction (XRD) results of all the prepared samples are highly consistent with the characteristic peaks of commercial RuO2 (Com-RuO2) in the rutile phase (JCPDS no.43-1027), indicating that a small amount of Cr and Sm doping does not significantly change the crystal structure of RuO2.

[0056] The experimental group catalyst sample Sm-Cr-RuO2 obtained in Example 2 was tested by scanning electron microscopy, and the results are shown in Figure 2 The scanning electron microscope images clearly show that the prepared Sm-Cr-RuO2 sample presents a two-dimensional nanosheet morphology.

[0057] The catalyst sample Sm-Cr-RuO2 obtained in Example 3 was tested by high-resolution transmission electron microscopy. Figure 3 The results showed that the prepared Sm-Cr-RuO2 catalyst powder was mainly composed of nanocrystals with a diameter of about 4 nm connected to each other, forming a mesoporous nanosheet structure.

[0058] The control group catalyst samples RuO2, Cr-RuO2 and the experimental group catalyst sample Sm-Cr-RuO2 obtained in Example 4, Comparative Examples 3 and 4 were subjected to electrochemical analysis. The results are shown in FIG. Figure 4 The OER performance of the control and experimental catalysts in 1M HClO4 electrolyte was evaluated using a standard three-electrode system. The electrochemical impedance spectroscopy (EIS) performed at a constant voltage of 1.5 V showed that the experimental catalyst Sm-Cr-RuO2 had the smallest charge transfer resistance (R ct =4.4Ω), confirming its enhanced electron transport capability and accelerated reaction kinetics ( Figure 4 a) The OER kinetics were further evaluated by Tafel slope. The results showed that the Tafel slope of Sm-Cr-RuO2 was low, only 35.7 mV dec. -1 , significantly lower than Cr-RuO2 (47.8mV dec -1 ) and RuO2(87.4mV dec -1 ), further proving that the Sm-Cr-RuO2 catalyst has faster OER reaction kinetics ( Figure 4 b).

[0059] The control group catalyst sample RuO2 and the experimental group catalyst sample Sm-Cr-RuO2 obtained in Example 5 and Comparative Example 5 were respectively made into electrolytic water membrane electrode assemblies (MEA) for single cell PEMWE. The test results are shown in FIG. Figure 5 The MEA prepared by using the experimental catalyst Sm-Cr-RuO2 has a high conductivity at 1A cm -2 The water electrolysis voltage under the electric density is only 1.580V, which is much lower than the 1.918V of the control group catalyst RuO2. At the same time, the MEA prepared by the experimental group catalyst is 3Acm -2 The water electrolysis voltage under high voltage is only 1.769V, which is much better than the 2025 target set by the U.S. Department of Energy (1.9V@3Acm -2 ), indicating its excellent performance as a PEMWE anode catalyst.

[0060] In addition to catalytic activity, the electrochemical stability of electrocatalysts is also a key evaluation index in electrocatalyst design. The OER performance of the Sm-Cr-RuO2 catalyst prepared in Example 5 in 1M HClO4 electrolyte was evaluated using a standard three-electrode system. Figure 6 (a) shows that the catalyst has a high conductivity at 100 mA cm -2 During the galvanostatic test of 850h, the potential remained stable without significant decay, which is superior to most of the reported advanced acidic OER electrocatalysts. Figure 6 As can be seen in (b), the electrolytic membrane electrode assembly made with this catalyst as the anode catalyst is -2 No significant activity decay was observed during the 50-hour galvanostatic test, further demonstrating that Cr and Sm doping significantly improves the stability of RuO2. These results indicate that Sm-Cr-RuO2 has great potential as an anode catalyst for industrial applications in PEMWE.

[0061] In summary, the present invention provides a preparation and application of a high-performance oxygen evolution catalyst suitable for use in high-strength acid electrolytes. The prepared Sm-Cr-RuO2 catalyst can be used as an anode material for acidic water electrolysis hydrogen production electrolytic cells, solving the problems of the limited variety, low activity, and poor stability of existing acidic OER catalysts. The prepared Sm-Cr-RuO2 catalyst exhibits excellent oxygen evolution activity and long-term stability in acidic media, surpassing the vast majority of reported related catalysts. Therefore, the present invention effectively overcomes the key shortcomings of the prior art and has high commercial value.

[0062] The above examples are intended to illustrate the embodiments disclosed herein and are not to be construed as limiting the present invention. In addition, the various modifications listed herein and variations of the methods and compositions in the invention will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. Although the present invention has been specifically described in conjunction with various specific preferred embodiments of the present invention, it should be understood that the present invention should not be limited to these specific embodiments. In fact, various modifications apparent to those skilled in the art as described above to obtain the invention should be included within the scope of the present invention.

Claims

1. A method for preparing a ruthenium oxide catalyst doped with single atoms of chromium and samarium, characterized in that: The steps include: S1. Fully heating and stirring the mixed solution to obtain a solid mixture, wherein the mixed solution includes a ruthenium salt, a chromium salt, a samarium salt, a chelating agent, a pH adjuster, and a template agent; S2. calcining the solid mixture and cooling it to obtain a catalyst.

2. The method for preparing a ruthenium oxide catalyst doped with single atoms of chromium and samarium according to claim 1, characterized in that: The step S1 includes at least one of the following technical features: The ruthenium salt is selected from one or more of ruthenium acetate, ruthenium nitrate and ruthenium chloride; The chromium salt is selected from at least one of chromium sulfate, chromium chloride, and chromium nitrate; The samarium salt is selected from at least one of samarium nitrate, samarium sulfate, samarium chloride, and samarium acetate; The chelating agent is tannic acid; The pH regulator and template agent are urea.

3. The method for preparing a ruthenium oxide catalyst doped with single atoms of chromium and samarium according to claim 2, characterized in that: The molar ratio of ruthenium salt, chromium salt and samarium salt in the mixed solution is (1-20):(0.5-1.5):1; the mass ratio of the tannic acid to the ruthenium salt is (1-30):1, and the mass ratio of the urea to the ruthenium salt is (10-50):

1.

4. The method for preparing a ruthenium oxide catalyst doped with single atoms of chromium and samarium according to claim 1, wherein: The stirring reaction temperature is 140-160 degrees, and the stirring reaction time is 5-200 minutes.

5. The method for preparing a ruthenium oxide catalyst doped with single atoms of chromium and samarium according to claim 1, characterized in that: In the step S2, the calcination atmosphere is air, the calcination temperature is 300-1000° C., the calcination time is 2-10 hours, and the catalyst is obtained after natural cooling.

6. A catalyst doped with single atoms of chromium and samarium, characterized in that: The method is obtained by any one of claims 1 to 5.

7. The catalyst doped with chromium or samarium single atoms according to claim 6, characterized in that: The catalyst-corresponding nanomaterial interface is composed of multi-component metal oxides containing three elements: ruthenium, chromium and samarium.

8. Use of the chromium and samarium single-atom doped catalyst as claimed in claim 6 as an anode material for acidic water electrolysis.

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