Yttrium-modified ruthenium oxide as well as preparation method and application thereof

Abstract

The invention belongs to the field of catalytic materials, and discloses yttrium-modified ruthenium oxide as well as a preparation method and application thereof. The method comprises the following steps: dissolving glucose and urea to obtain a solution a; ruCl3 and YCl3. 6H2O are added into the solution a, and a solution b is obtained; treating the solution b at 130-150 DEG C for 4-6 hours to form a porous foamed gel solid precursor; grinding the gel solid precursor into fine powder; and calcining to prepare ruthenium oxide modified by yttrium in different proportions. Yttrium-modified ruthenium oxide is prepared through a sol-gel method, and modification of yttrium not only reduces the loading capacity of precious metal, but also improves the activity and stability of the ruthenium oxide in acidic OER. Ruthenium oxide is modified by rare earth element yttrium, so that the electronic structure of the material is improved, the number of active sites is increased, rapid release of gas is facilitated, and the electrocatalytic activity and stability of the material are synergistically improved.

Description

Technical Field

[0001] The invention belongs to the field of catalytic materials, and in particular relates to yttrium-modified ruthenium oxide, a preparation method thereof, and application thereof in acidic electrocatalytic oxygen evolution reaction. Background Art

[0002] Nowadays, due to the growing demand for energy and excessive consumption of fossil fuels, this inevitably leads to energy depletion and a large amount of carbon dioxide emissions, thereby exacerbating environmental pollution. Therefore, people turn to clean renewable energy to reduce the negative impact on the environment and achieve sustainable development.

[0003] Among many renewable energy sources, hydrogen (H2) is an ideal alternative energy source for traditional fossil fuels due to its high energy density and pollution-free. Hydrogen production by water electrolysis can produce high-purity hydrogen under mild conditions at room temperature and pressure without emitting carbon dioxide. At present, the main water electrolysis hydrogen production technologies are alkaline anion exchange membrane water electrolyzer (AEMWE, Anion Exchange Membrane Water Electrolyzer) and acidic proton exchange membrane water electrolyzer (PEMWE, Proton Exchange Membrane Water Electrolysis) technology, among which PEMWE technology has attracted widespread attention due to its high operating current density, faster response rate, and lower ohmic conductivity. However, in the PEMWE hydrogen production process, the anode is highly corrosive (pH is 0-3) and oxidizing, which leads to poor stability of the anode oxygen evolution reaction (OER) catalyst, so there is a bottleneck in the H2 production process.

[0004] At present, noble metal iridium oxide (IrO2) and ruthenium oxide (RuO2) are considered as benchmark electrocatalysts for acidic OER due to their high efficiency, stability and good corrosion resistance. Compared with IrO2, RuO2 has a lower price and higher intrinsic activity, and RuO2 is considered to be the most promising material to replace commercial IrO2. However, Ru cations will be over-oxidized to produce soluble substances (Ru n + , n>4), which causes the catalyst crystal structure to collapse, resulting in very poor stability of RuO2. Therefore, how to improve the stability and activity of RuO2 and reduce the loading of precious metals will be a huge challenge for the practical application of PEMWE. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present application provides an yttrium-modified ruthenium oxide (catalytic material) and a preparation method and application thereof.

[0006] The technical solution adopted in this application is:

[0007] A method for preparing yttrium-modified ruthenium oxide comprises the following steps:

[0008] (1) dissolving glucose in water at a ratio of 4.5-6.5 g / 5 ml and dissolving urea in water at a ratio of 0.8-1.2 g / 5 ml to obtain solution a;

[0009] (2) adding RuCl3 and YCl3·6H2O to solution a, wherein the molar percentage of YCl3·6H2O added relative to RuCl3 is ≤25 mol%, and the mass ratio of the total mass of RuCl3 and YCl3·6H2O added to the mass of glucose in solution a is (35 mg-55 mg):(4.5 g-6.5 g), and mixing well to obtain solution b;

[0010] (3) treating solution b at 130-150°C for 4-6h to obtain a solid gel precursor;

[0011] (4) grinding the gel solid precursor into fine powder;

[0012] (5) The fine powder is heated to 470-530° C. at a rate of 2-5° C. / min in an air atmosphere, kept at this temperature for 7-9 hours, and cooled to room temperature to obtain yttrium-modified ruthenium oxide.

[0013] In some of the embodiments, in step (2), RuCl3 and YCl3·6H2O are added to solution a, wherein the mass ratio of the total amount of RuCl3 and YCl3·6H2O added to the mass ratio of glucose in solution a is (35mg-55mg):(4.5g-6g), and the mixture is mixed evenly to obtain solution b.

[0014] In some of the embodiments, in step (3), solution b is treated at 130-150° C. for 4-6 hours. After the solution changes from a flowing state to a fully solid state, uniform bubbles of 2.8-3.2 mm are observed with the naked eye to obtain a gel solid precursor.

[0015] In some embodiments, in step (4), the gel solid precursor is ground into fine powder with a size of 200-400 microns.

[0016] In some of the embodiments, in step (5), the fine powder is heated to 480-520° C. at a rate of 2-5° C. / min in an air atmosphere, kept at this temperature for 7.5-8.5 h, and cooled to room temperature to obtain yttrium-modified ruthenium oxide.

[0017] In some preferred embodiments, in step (2), the added amount of YCl3·6H2O is 6 mol%-25 mol% relative to the molar percentage of RuCl3.

[0018] In some preferred embodiments, in step (2), the added amount of YCl3·6H2O is 12 mol%-25 mol% relative to the molar percentage of RuCl3.

[0019] The invention discloses yttrium-modified ruthenium oxide, wherein the ruthenium oxide is modified with yttrium element, and the molar percentage of the yttrium element relative to the ruthenium element is not higher than 25 mol% (≤25%).

[0020] In some of the embodiments, the yttrium-modified ruthenium oxide is prepared by any of the preparation methods described above.

[0021] Application of yttrium-modified ruthenium oxide in acidic electrocatalytic oxygen evolution reaction. The yttrium-modified ruthenium oxide is as described above, or is obtained by the above preparation method.

[0022] The beneficial effects of this application are:

[0023] The present application prepares ruthenium oxide modified with yttrium in different proportions by a gel method and subsequent calcination. The ruthenium oxide catalyst prepared by yttrium modification exhibits excellent catalytic activity in the acidic OER process.

[0024] The yttrium-modified ruthenium oxide (Y-18) prepared in Example 4 of the present application has excellent electrocatalytic oxygen evolution performance. 2 The OER overpotential is only 204 mV, which is better than the ruthenium oxide without yttrium modification in Example 1 (277 mV).

[0025] The present application prepares yttrium-modified ruthenium oxide by the sol-gel method. The modification of yttrium not only reduces the precious metal loading but also improves its activity and stability in acidic OER. By modifying ruthenium oxide with the rare earth element yttrium, the electronic structure of the material is improved and the number of active sites is increased, which is conducive to the rapid release of gas and synergistically improves the electrocatalytic activity and stability of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the SEM image of RuO2 in Example 1.

[0027] Figure 2 This is the SEM image of Y-18 in Example 4.

[0028] Figure 3 These are the XRD diffraction patterns of the materials of Example 1 (RuO2), Example 2 (Y-6), Example 3 (Y-12), Example 4 (Y-18), and Example 5 (Y-24) and the comparison diagram with the standard cards.

[0029] Figure 4These are the OER polarization curves of the materials of Example 1 (RuO2), Example 2 (Y-6), Example 3 (Y-12), Example 4 (Y-18), and Example 5 (Y-24).

[0030] Figure 5 It is a graph of the difference in current density and scanning rate of the materials of Example 1 (RuO2), Example 2 (Y-6), Example 3 (Y-12), Example 4 (Y-18), and Example 5 (Y-24). DETAILED DESCRIPTION

[0031] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0032] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.

[0034] In the present invention, the term "multiple" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0035] Notes on related elements in the embodiment:

[0036] Ruthenium is a hard, brittle, light grey, multivalent rare metal with the element symbol Ru and the atomic number 44. It is located in the VIII group of the fifth period and belongs to the d-block metal. Ruthenium is a member of the platinum group metals. Its content in the earth's crust is only one billionth, making it one of the rarest metals. The crystal structure of ruthenium metal is hexagonal, with a melting point of 2334°C, a boiling point of 4150°C, and a density of 12.45 g / cm at room temperature. 3 , atomic radius is 133 pm, first ionization energy is 710.2 kJ·mol -1. It is very stable and corrosion-resistant. It can resist the corrosion of hydrochloric acid, sulfuric acid, nitric acid and aqua regia at room temperature. Ruthenium is the cheapest metal among the platinum group metals, although other metals such as platinum and palladium are more abundant than ruthenium. Ruthenium is widely used in electronic information, medicine, electrochemistry and other fields. At the same time, ruthenium and its complexes have good catalytic activity and can be used as catalysts in many types of chemical reactions.

[0037] Yttrium is a gray-black metal with the chemical symbol Y. It is the first rare earth metal element discovered and is ductile. It can react with hot water and is easily soluble in dilute acid. It can be used to make special glass and alloys.

[0038] Iridium, a metallic element, has the symbol Ir, atomic number 77, and atomic weight 192.22. Its name comes from Latin, which means "rainbow". Iridium is present in the earth's crust at a content of one ten-millionth, and is often dispersed in various ores in alluvial and placer deposits together with platinum group elements.

[0039] Related compounds and molecular weight annotations in the examples:

[0040] Glucose, chemical formula is C6H 12 O6, molecular weight is 180.16.

[0041] Urea, also known as urea or carbonamide, has a chemical formula of CH4N2O or CO(NH2)2. It is an organic compound composed of carbon, nitrogen, oxygen and hydrogen. It is a white crystal. It is one of the simplest organic compounds and the main nitrogen-containing end product of protein metabolism in mammals and some fish. Its molecular weight is 60.06.

[0042] RuCl3, or ruthenium trichloride, is a chemical substance with a molecular weight of 207.43.

[0043] YCl3·6H2O, also known as yttrium chloride hexahydrate, is a rare earth compound. Its molecular weight is 303.36.

[0044] A method for preparing yttrium-modified ruthenium oxide comprises the following steps:

[0045] (1) dissolving glucose in water at a ratio of 4.5-6.5 g / 5 ml and dissolving urea in water at a ratio of 0.8-1.2 g / 5 ml to obtain solution a;

[0046] (2) adding RuCl3 and YCl3·6H2O to solution a, wherein the molar percentage of YCl3·6H2O added relative to RuCl3 is ≤25 mol%, and the mass ratio of the total mass of RuCl3 and YCl3·6H2O added to the mass of glucose in solution a is (35 mg-55 mg):(4.5 g-6.5 g), and mixing well to obtain solution b;

[0047] (3) treating solution b at 130-150° C. for 4-6 h to form a porous foam-like gel solid precursor;

[0048] (4) grinding the gel solid precursor into fine powder;

[0049] (5) The fine powder is heated to 470-530° C. at a rate of 2-5° C. / min in an air atmosphere, kept at this temperature for 7-9 hours, and cooled to room temperature to obtain yttrium-modified ruthenium oxide.

[0050] In some of the embodiments, in step (1), glucose is dissolved in water at a ratio of 4.5-6.5 g / 5 ml, and urea is dissolved in water at a ratio of 0.8-1.2 g / 5 ml to obtain solution a. The decomposition products of urea and glucose form a gel network through a condensation reaction. Glucose acts as a structure-directing agent, and glucose forms a specific coordination structure with the metal ions in RuCl3 and YCl3·6H2O. A decrease in the amount of glucose will not be able to completely coordinate with the metal ions, affecting the structure; an increase in the amount of glucose may cause the gel solid precursor to have residues after calcination, affecting the performance of the catalyst. Urea decomposes at around 140 degrees Celsius to produce gas (ammonia and carbon dioxide), which acts as a foaming agent to help form a porous structure. Too much urea will produce too much gas in the gel to form larger pores, resulting in defects and unevenness on the catalyst; too low a content will not be enough to form enough bubbles, and the gel will not be completely gelled. The gel network is further thermally decomposed, the organic components are burned off, and the metal oxides are left. Through research, the inventors have optimized the mass ratio of glucose to urea to be (4-6):(0.8-1.2).

[0051] The chemical formula of glucose is C6H 12 O6, molecular weight is 180.16. Glucose is an aldohexose, white crystal, easily soluble in water, sweet, melting point is 146 ° C. The inventor found in the study that glucose is used as a structural directing agent for metal ions. Under the premise that sucrose and fructose have different chemical structures and properties from glucose, if sucrose and fructose are used to replace glucose, the performance of the nanomaterial as a catalyst will be affected, so the yttrium-modified ruthenium oxide with excellent performance of the present application cannot be prepared.

[0052] In some of the embodiments, the added amount of YCl3·6H2O is not higher than 25 mol % of RuCl3.

[0053] The addition amount of YCl3·6H2O is 0-25 mol%, which is selected according to the catalytic performance of acidic OER. Too much or too little will affect the performance of acidic OER. Too much Y modification will lead to excessive occupation of catalytic active sites, and may also cause lattice distortion, affecting the stability of the catalyst. Too little Y modification will make it impossible to utilize the advantages of Y's electronic structure optimization, resulting in no obvious improvement in catalytic performance.

[0054] In some preferred embodiments, in step (2), the added amount of YCl3·6H2O is 6 mol%-25 mol% relative to the molar percentage of RuCl3.

[0055] In some preferred embodiments, in step (2), the added amount of YCl3·6H2O is 12 mol%-25 mol% relative to the molar percentage of RuCl3.

[0056] In some preferred embodiments, in step (2), RuCl3 and YCl3·6H2O are added to solution a, wherein the mass ratio of the sum of the added amounts of RuCl3 and YCl3·6H2O to the glucose in solution a is (35mg-55mg):(4.5g-6g), and the mixture is mixed evenly to obtain solution b.

[0057] In some of the embodiments, in step (3), solution b is treated at 130-150° C. for 4-6 hours, and the solution changes from a flowing state to a fully solid state and then stabilizes, and uniform bubbles of 2.8-3.2 mm can be observed with the naked eye, indicating that the reaction endpoint has been reached and a gel solid precursor is obtained.

[0058] In some embodiments, in step (4), the gel solid precursor is ground into fine powder with a size of 200-400 microns.

[0059] In some of the embodiments, in step (5), the fine powder is heated to 480-520° C. at a rate of 2-5° C. / min in an air atmosphere, kept at this temperature for 7.5-8.5 h, and cooled to room temperature to obtain yttrium-modified ruthenium oxide.

[0060] A lower calcination temperature results in incomplete combustion of glucose and urea, carbon residue and no product formation, which will affect the purity and activity of the catalyst. A higher calcination temperature increases the crystallinity of the product and causes grain growth, resulting in a decrease in specific surface area. The pore structure changes, affecting the catalytic activity.

[0061] The calcination time determines the degree of combustion of glucose and urea. Too short a calcination time will result in incomplete combustion, while too long a calcination time will result in excessive sintering and excessive grain growth, thus reducing the specific surface area and number of active sites of the catalyst.

[0062] The technical solution of the invention is simple, highly operable and easy to repeat.

[0063] Those skilled in the art can also scale up the raw materials according to the ratios in the examples to obtain conditions for industrial production.

[0064] The porcelain boat mentioned in the embodiment, also called a combustion boat, is a chemical porcelain. The porcelain boat used in the embodiment is used for high-temperature calcination in a matching muffle furnace. Those skilled in the art can select suitable equipment and matching containers for high-temperature calcination as needed.

[0065] A yttrium-modified ruthenium oxide, wherein the ruthenium oxide is modified with yttrium element, and the molar percentage of the yttrium element relative to the ruthenium element is not higher than 25mol% (≤25%).

[0066] Modification mainly refers to the specific chemical treatment or change of molecules or substances to change their properties, functions or structures. This usually involves chemical treatment on the surface of the substrate material, with the purpose of changing the chemical properties of the surface so that it can interact with other substances. It is widely used in catalysis, medicine, environmental engineering and other fields.

[0067] Doping is more "deep" and involves adding impurity elements inside the material. Doping usually has a wide range of applications in many aspects. In nanotechnology, the size, shape and electronic properties of materials are controlled by adding different impurity elements.

[0068] The application scenarios of the yttrium-modified ruthenium oxide include use as a catalyst in acidic electrocatalytic oxygen evolution reaction, can be used in proton exchange membrane water electrolyzer to produce hydrogen; metal air battery, etc.

[0069] In step C of the embodiment, when the solution changes from a flowing state to a fully solid state and stabilizes, uniform bubbles of 2.8-3.2 mm can be observed with the naked eye, indicating that the reaction endpoint has been reached and a gel solid precursor has been obtained.

[0070] The following is a description with reference to specific embodiments.

[0071] Example 1: Preparation of pure ruthenium oxide material (RuO2)

[0072] A. First, dissolve 4.8 g of glucose and 1 g of urea in a beaker containing 5 mL of deionized water and stir evenly to obtain solution a;

[0073] B. Then, 40 mg of anhydrous RuCl3 was added to solution a, and the mixture was stirred for 60 min to obtain a uniform solution b;

[0074] C. Take out the magnet of solution b, place solution b in an oven at 130°C for 5 hours to form a porous foamy gel solid precursor. Then, grind the sol solid into fine powder in an agate mortar.

[0075] D. Place the fine powder ground in step C evenly in a magnetic boat and place it in a muffle furnace. Raise the temperature to 490°C at a rate of 2-5°C / min in an air atmosphere, keep the temperature for 8 hours, cool to room temperature, and obtain ruthenium oxide after grinding. Figure 1 This is the SEM image of ruthenium oxide (RuO2) in Example 1.

[0076] Figure 1 a The rough foam structure of ruthenium oxide (RuO2) can be observed, which is beneficial to improving the catalytic activity. Figure 1 b is an enlarged SEM image, from which a rough foam structure composed of compact nanospheres can be observed. The rough foam structure can increase the specific surface area of ​​the catalyst, which is beneficial to the enhancement of the catalyst activity.

[0077] Example 2: Preparation of 6% yttrium-modified ruthenium oxide material (abbreviated as Y-6)

[0078] A. First, dissolve 4.8 g of glucose and 1 g of urea in a beaker containing 5 mL of deionized water and stir evenly to obtain solution a;

[0079] B. Then, 40 mg of anhydrous RuCl3 and 3.6 mg of YCl3·6H2O were added to solution a, and the mixture was stirred for 60 min to obtain a uniform solution b;

[0080] C. Take out the magnet of solution b, place solution b in an oven at 130°C for 5 hours to form a porous foamy gel solid precursor. Then, grind the sol solid into fine powder in an agate mortar;

[0081] D. The fine powder ground in step C is evenly placed in a magnetic boat and placed in a muffle furnace. The temperature is raised to 490°C at a rate of 2-5°C / min in an air atmosphere, kept at this temperature for 8 hours, cooled to room temperature, and yttrium-modified ruthenium oxide (Y-6) is obtained after grinding.

[0082] Example 3: Preparation of yttrium-modified ruthenium oxide material with a molar ratio of 12% (abbreviated as Y-12)

[0083] A. First, dissolve 4.8 g of glucose and 1 g of urea in a beaker containing 5 mL of deionized water and stir evenly to obtain solution a;

[0084] B. Then, 40 mg of anhydrous RuCl3 and 7.2 mg of YCl3·6H2O were added to solution a, and the mixture was stirred for 60 min to obtain a uniform solution b;

[0085] C. Take out the magnet of solution b, place solution b in an oven at 130°C for 5 hours to form a porous foamy gel solid precursor. Then, grind the sol solid into fine powder in an agate mortar;

[0086] D. Place the fine powder ground in step C evenly in a magnetic boat and place it in a muffle furnace. Heat it to 490°C at a rate of 2-5°C / min in an air atmosphere, keep it warm for 8 hours, cool it to room temperature, and grind to obtain yttrium-modified ruthenium oxide (Y-12).

[0087] Example 4: Preparation of 18% yttrium-modified ruthenium oxide material (abbreviated as Y-18)

[0088] A. First, dissolve 4.8 g of glucose and 1 g of urea in a beaker containing 5 mL of deionized water and stir evenly to obtain solution a;

[0089] B. Then, 40 mg of anhydrous RuCl3 and 10.8 mg of YCl3·6H2O were added to solution a, and the mixture was stirred for 60 min to obtain a uniform solution b;

[0090] C. Take out the magnet of solution b, place solution b in an oven at 130°C for 5 hours to form a porous foamy gel solid precursor. Then, grind the sol solid into fine powder in an agate mortar;

[0091] D. The fine powder ground in step C is evenly placed in a magnetic boat and placed in a muffle furnace. The temperature is raised to 490°C at a rate of 2-5°C / min in an air atmosphere, kept at this temperature for 8 hours, cooled to room temperature, and yttrium-modified ruthenium oxide (Y-18) is obtained after grinding. Figure 2 This is the SEM image of Y-18 of Example 4.

[0092] Figure 2 a also observed and Figure 1 a similar rough foam structure, Figure 2 The shape of b is also similar to Figure 1 b Similar in appearance. Figure 1 By comparison, it is shown that the use of yttrium to modify ruthenium oxide in the present application does not change the morphology of ruthenium oxide.

[0093] Example 5: Preparation of 24% yttrium-modified ruthenium oxide material (abbreviated as Y-24)

[0094] A. First, dissolve 4.8 g of glucose and 1 g of urea in a beaker containing 5 mL of deionized water and stir evenly to obtain solution a;

[0095] B. Then, 40 mg of anhydrous RuCl3 and 14.4 mg of YCl3·6H2O were added to solution a, and the mixture was stirred for 60 min to obtain a uniform solution b;

[0096] C. Take out the magnet of solution b, place solution b in an oven at 130°C for 5 hours to form a porous foamy gel solid precursor. Then, grind the sol solid into fine powder in an agate mortar;

[0097] D. The fine powder ground in step C is evenly placed in a magnetic boat and placed in a muffle furnace. The temperature is raised to 490°C at a rate of 2-5°C / min in an air atmosphere, kept at this temperature for 8 hours, cooled to room temperature, and yttrium-modified ruthenium oxide (Y-24) is obtained after grinding.

[0098] The difference between Example 1 and Example 4 is that the RuO2 nanomaterial is prepared without adding the YCl3·6H2O precursor. Figure 1 This is the SEM image of RuO2 obtained in Example 1.

[0099] The difference between Example 2 and Example 4 is that the mass of the added YCl3·6H2O precursor is 3.6 mg, and the Y-6 nanomaterial is obtained.

[0100] The difference between Example 3 and Example 4 is that the mass of the added YCl3·6H2O precursor is 7.2 mg, and the Y-12 nanomaterial is obtained.

[0101] The difference between Example 5 and Example 4 is that the mass of the added YCl3·6H2O precursor is 14.4 mg, and the Y-24 nanomaterial is obtained.

[0102] The performance of the yttrium-modified ruthenium oxide nanomaterial of the embodiment of the present application was analyzed.

[0103] Test Example 1: XRD diffraction analysis

[0104] XRD diffraction analysis was performed on the yttrium-modified ruthenium oxide nanomaterials of Examples 1 to 5, and the results are shown in Figure 3 .

[0105] The present invention prepares ruthenium oxide modified with yttrium in different proportions by a sol-gel method. Figure 3 The XRD diffraction pattern proves that the preparation is successful. Figure 3 In the figure, RuO2 represents the ruthenium oxide prepared in Example 1, and Y-6, Y-12, Y-18, and Y-24 represent the yttrium-modified ruthenium oxide nanomaterials prepared in Examples 2-5, respectively.

[0106] Figure 3As shown in FIG. 1 , the peak of the XRD spectrum of the Y-modified ruthenium oxide is not shifted compared with the ruthenium oxide of Example 1, indicating that Y may exist in an amorphous or smaller form.

[0107] Test Example 2: Electrochemical Test

[0108] The nanomaterials prepared in the examples were subjected to electrochemical tests. The electrochemical tests were conducted in 0.5M H2SO4 using a three-electrode system of an electrochemical workstation. Glassy carbon electrode (GC), graphite sheet and mercury-mercurous sulfate electrode were selected as working electrode, counter electrode and reference electrode, respectively. The overpotential (η) was calculated according to the following equation: η = E RHE -1.23 V. Linear sweep voltammetry (LSV) was recorded in 0.5 M H2SO4 solution at a scan rate of 5 mV / s to obtain polarization curves. All electrode potential data were compensated for 95% voltage drop. Results are shown in Figure 4 and Table 1.

[0109] Figure 4 It can be seen that the yttrium-modified ruthenium oxide (Y-18) prepared in Example 4 has excellent electrocatalytic oxygen evolution performance. Figure 4 The OER polarization curve can be observed at a current density of 10 mA / cm 2 The overpotential is only 204mV, which is better than the ruthenium oxide (277mV) in Example 1. The test process uses the same mass of nanomaterials (catalysts) to prepare ink and drip it onto the glassy carbon electrode for testing. Because the so-called catalysts have the same mass, the ruthenium oxide contains precious metal ruthenium, while the yttrium-modified ruthenium oxide contains non-precious metal yttrium, so the use of yttrium-modified ruthenium oxide nanomaterials reduces the loading of precious metal ruthenium.

[0110] Table 1

[0111]

[0112] The present invention not only reduces the noble metal loading but also improves the activity and stability of ruthenium oxide in acidic OER by using yttrium-modified ruthenium oxide, which is of great significance for the practical application of PEMWE.

[0113] The present application can significantly reduce the overpotential by modifying ruthenium oxide with yttrium. The overpotential of the best yttrium-modified ruthenium oxide (Y-18) is reduced by 73mV compared to ruthenium oxide, while the overpotential reduction of ruthenium oxide modified by doping strategy is limited.

[0114] It can be seen that the Y content directly affects the performance of acidic OER (current density of 10 mA / cm 2Overpotential), too much Y modification will lead to excessive occupation of the catalytic active sites on the yttrium-modified ruthenium oxide nanomaterials, and too little Y modification will result in the yttrium-modified ruthenium oxide nanomaterials being unable to fully utilize the advantages of Y's electronic structure optimization.

[0115] Acidic proton exchange membrane water electrolyzer (PEMWE) generally requires the anode to be at 10mA / cm 2 The overpotential of the current density is less than 250mV, and the optimal value is less than 230mV. Therefore, the yttrium-modified ruthenium oxide nanomaterials prepared in Examples 2-5 of the present application can meet the requirements for catalysts in acidic electrocatalytic oxygen evolution reactions. More preferred are the yttrium-modified ruthenium oxide nanomaterials prepared in Examples 3-5. That is, preferably, the molar percentage of YCl3·6H2O added relative to RuCl3 is 12mol%-25mol%.

[0116] Test Example 3: Electrochemical Cyclic Voltammetry Test

[0117] Through the electrochemical cyclic voltammetry test at different scan rates, the results can be seen in Figure 5 and Table 2.

[0118] After data processing, the double layer capacitance value ( Figure 5 The slope value of the curve is proportional to the number of active sites of the catalyst. The double-layer capacitance of ruthenium oxide modified with yttrium is improved compared with RuO2, among which Y-18 has the largest double-layer capacitance value, indicating that yttrium modification improves the electronic structure of ruthenium oxide material and increases the number of active sites.

[0119] and Figure 5 The relevant data are shown in Table 2.

[0120] Table 2

[0121]

[0122] Example 6: Preparation of 18% yttrium-modified ruthenium oxide material (abbreviated as Y-18)

[0123] A. First, dissolve 5.6 g of glucose and 1.2 g of urea in a beaker containing 5 mL of deionized water and stir evenly to obtain solution a;

[0124] B. Then, 40 mg of anhydrous RuCl3 and 10.8 mg of YCl3·6H2O were added to solution a, and the mixture was stirred for 60 min to obtain a uniform solution b;

[0125] C. Take out the magnet of solution b, place solution b in an oven at 150°C for 5 hours to form a porous foamy gel solid precursor. Then, grind the sol solid into fine powder in an agate mortar;

[0126] D. Place the fine powder ground in step C evenly in a magnetic boat and place it in a muffle furnace. Raise the temperature to 520°C at a rate of 2-5°C / min in an air atmosphere, keep warm for 8 hours, cool to room temperature, and obtain yttrium-modified ruthenium oxide (Y-18) after grinding.

[0127] Example 7: Preparation of 18% yttrium-modified ruthenium oxide material (abbreviated as Y-18)

[0128] A. First, dissolve 5.3 g of glucose and 1.2 g of urea in a beaker containing 5 mL of deionized water and stir evenly to obtain solution a;

[0129] B. Then, 40 mg of anhydrous RuCl3 and 10.8 mg of YCl3·6H2O were added to solution a, and the mixture was stirred for 60 min to obtain a uniform solution b;

[0130] C. Take out the magnet of solution b, place solution b in an oven at 150°C for 5 hours to form a porous foamy gel solid precursor. Then, grind the sol solid into fine powder in an agate mortar;

[0131] D. Place the fine powder ground in step C evenly in a magnetic boat and place it in a muffle furnace. Heat it to 510°C at a rate of 2-5°C / min in an air atmosphere, keep it warm for 8 hours, cool it to room temperature, and grind to obtain yttrium-modified ruthenium oxide (Y-18).

[0132] Comparative Example 1

[0133] In the prior art, ruthenium oxide is obtained by doping with different elements. The overpotential analysis before and after doping is shown in Table 3.

[0134] Table 3

[0135] Doping elements Overpotential of ruthenium oxide Overpotential after doping References Mn 300mV 208mV EnergyEnviron.Sci.,2022,15,2356-2365 Ni 227mV 214mV Nat. Mater., 2023, 22, 100-108 Nb 233mV 204mV Joule, 2023, 7, 558-573 Nd 275mV 211mV Adv.Funct.Mater.,2023,33,2213304 Re 258mV 190mV Nat. Commun.,2023,14,354 In 227mV 187mV Angew.Chem.Int.Ed,136,e202316903

[0136] It can be seen from Table 3 that the overpotential reduction of ruthenium oxide after modification by the doping strategy is limited, which is not as good as the technical solution of the present application.

[0137] Comparative Example 2

[0138] The addition amount of urea was changed, and the contents of other components and the preparation method were the same as those in Example 2.

[0139] The amount of urea added was 0.6 g, resulting in an incompletely gelled gel solid and insufficient bubbles on the gel. Since a porous gel structure could not be formed, the subsequent steps could not be performed.

[0140] The amount of urea added was 1.4 g, and a gel solid was obtained, wherein the pores in the gel structure were very large and the pores were unevenly dispersed, resulting in defects and unevenness on the catalyst.

[0141] Comparative Example 3

[0142] The temperature and holding time in step D were changed, and the remaining steps were the same as those in Example 3. The contents of other components were also the same as those in Example 3.

[0143] The mixture was placed in an oven at 110°C for 3 hours to obtain an incompletely gelled gel solid.

[0144] After being placed in an oven at 170°C for 7 hours, the resulting gel had collapsed structure and was over-aged, which affected the activity and stability of the catalyst. Subsequent performance tests could not be performed.

[0145] In summary, the present application prepares yttrium-modified ruthenium oxide by the sol-gel method. The rare earth element yttrium is used to modify ruthenium oxide, which improves the electronic structure of the nanomaterial and increases the number of active sites, which is beneficial to the rapid release of gas and synergistically improves the electrocatalytic activity and stability of the material.

[0146] The above is a further detailed description of the present invention, which should not be regarded as a limitation on the specific implementation of the present invention. For ordinary technicians in the technical field to which the present invention belongs, simple deduction or replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A method for preparing yttrium-modified ruthenium oxide, characterized in that: The following steps are involved: (1) dissolving glucose in water at a ratio of 4.5-6.5 g / 5 ml and dissolving urea in water at a ratio of 0.8-1.2 g / 5 ml to obtain solution a; (2) adding RuCl3 and YCl3·6H2O to solution a, wherein the molar percentage of YCl3·6H2O added relative to RuCl3 is ≤25 mol%, and the mass ratio of the total mass of RuCl3 and YCl3·6H2O added to the mass of glucose in solution a is (35 mg-55 mg):(4.5 g-6.5 g), and mixing well to obtain solution b; (3) treating solution b at 130-150°C for 4-6h to obtain a solid gel precursor; (4) grinding the gel solid precursor into fine powder; (5) The fine powder is heated to 470-530° C. at a rate of 2-5° C. / min in an air atmosphere, kept at this temperature for 7-9 hours, and cooled to room temperature to obtain yttrium-modified ruthenium oxide.

2. The preparation method according to claim 1, characterized in that: Step (3) treating solution b at 130-150° C. for 4-6 hours, and after the solution changes from a fluid state to a fully solid state, uniform bubbles of 2.8-3.2 mm are observed with the naked eye, thereby obtaining a gel solid precursor.

3. The preparation method according to claim 1, characterized in that: In step (4), the gel solid precursor is ground into fine powder with a size of 200-400 microns.

4. The preparation method according to claim 1, characterized in that: In step (5), the fine powder is heated to 480-520° C. at a rate of 2-5° C. / min in an air atmosphere, kept at this temperature for 7.5-8.5 hours, and cooled to room temperature to obtain yttrium-modified ruthenium oxide.

5. The preparation method according to claim 1, characterized in that: In step (2), the added amount of YCl3·6H2O is 6 mol%-25 mol% relative to the molar percentage of RuCl3.

6. The preparation method according to claim 5, characterized in that: In step (2), the added amount of YCl3·6H2O is 12 mol%-25 mol% relative to the molar percentage of RuCl3.

7. A yttrium-modified ruthenium oxide, characterized in that: Ruthenium oxide is modified with yttrium element, and the molar percentage of yttrium element relative to ruthenium element is not higher than 25 mol%.

8. The yttrium-modified ruthenium oxide according to claim 7, characterized in that: The yttrium-modified ruthenium oxide is prepared by the preparation method described in any one of claims 1-6.

9. Use of the yttrium-modified ruthenium oxide according to any one of claims 7 to 8 in an acidic electrocatalytic oxygen evolution reaction.

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