A method for preparing Y2Ru2O7

Abstract

The application provides a preparation method of Y2Ru2O7, wherein a ruthenium salt and a yttrium salt are dissolved in water, a water-soluble polymer chelating agent is continuously added, and the mixture is uniformly mixed; the obtained mixture is evaporated at 120-140 DEG C to obtain a fluffy precursor; the fluffy precursor is heated to 600-700 DEG C, and is kept for 6-8 hours; then the temperature is increased to 1000-1100 DEG C, and is kept for 12-18 hours; and after natural cooling, the Y2Ru2O7 is obtained; by selecting a water-soluble polymer as a chelating agent, Y 3+ reacts easily with Ru 3+ ions, the product has high purity, XRD shows that it is a homogeneous Y2Ru2O7 pyrochlore material, has good electrocatalytic performance, the catalyst has an oxygen evolution reaction overpotential of 190-240 mV under a current density of 10 mA cm ‑ ², has an overpotential of 350 mV under a current density of 100 mA cm ‑ ², and can be stably operated for 22-30 hours under a current density of 10 mA cm ‑ ².

Description

Technical Field

[0001] This invention belongs to the field of inorganic materials and electrocatalytic materials technology, specifically relating to a method for preparing yttrium and ruthenium pyrochlore oxide (Y2Ru2O7) using water-soluble polymers through a high-temperature heating process. Background Technology

[0002] Pyrochlore (A₂B₂O₇) is a type of metal oxide with a unique crystal structure. Its lattice contains abundant oxygen vacancies and moduloizable metal cations. By controlling the composition of the metal elements at the A and B sites, the electronic structure and catalytic performance can be optimized, exhibiting excellent OER catalytic potential. Furthermore, pyrochlore possesses certain chemical and thermal stability, making it suitable for application in acidic environments. Both Y and Ru exhibit high activity and performance in electrocatalysis, and are relatively inexpensive; therefore, Y₂Ru₂O₇ shows great promise for development in acidic OER processes involving water electrolysis for hydrogen production.

[0003] Traditional pyrochlore preparation often employs a high-temperature solid-state method, which involves mixing A and B source oxides or carbonates in stoichiometric ratios and then calcining them at high temperatures for an extended period to obtain the product. The synthesis of Y2Ru2O7 follows the same principle, where the product is obtained by simply calcining a mixture of yttrium and ruthenium metal source compounds. However, this method has the following drawbacks: (1) Poor mixing uniformity: Solid-state grinding and mixing makes it difficult to achieve uniform dispersion, and the distribution of metal salts is difficult to be uniform, which can easily lead to the presence of impurities in the product and affect the material properties. (2) Simple calcination process: The size, porosity, and specific surface area of ​​the product are easily controlled by temperature. A simple high-temperature heating procedure cannot calcine the Y2Ru2O7 to achieve the best catalytic performance. Furthermore, excessively high temperatures result in high energy consumption, while excessively low temperatures can easily lead to particle agglomeration. (3) During the preparation of the precursor, the precursor prepared by general chelating agents is relatively compact, with a small specific surface area and insufficient fluffiness.

[0004] In the existing technology, there is no systematic patent protection for the preparation method of Y2Ru2O7 pyrochlore using water-soluble polymers, and there are problems such as unclear precursor ratio, vague and simple calcination process parameters, making it difficult to stably prepare high-purity and high-crystallinity Y2Ru2O7 pyrochlore materials.

[0005] Patent CN118792695B discloses a rapid preparation method for a multi-strain ruthenium-based pyrochlore catalyst. Yttrium nitrate, ruthenium trichloride, and potassium citrate are added to deionized water and mixed evenly. Citric acid is continuously added under stirring to adjust the pH of the solution to 3-5, resulting in a first mixed solution. The first mixed solution is stirred and reacted at 80-95℃ for 5-10 hours to obtain a gel. The gel is vacuum dried at 60-100℃ for 10-12 hours to obtain gel solid particles. The gel solid particles and potassium chloride are mixed and ground into powder. The powder is then placed in the graphite sample stage groove of a tube furnace and subjected to Joule heat treatment in an air atmosphere. After washing and vacuum drying, a multi-strain ruthenium-based pyrochlore catalyst is obtained. In step (3), the Joule heat treatment conditions are: heat treatment temperature 800-1500℃, heating rate 1000-4000℃ / s, and 4-10 Joule heat treatments. In 0.1M HClO4 aqueous solution, 10mA·cm -2 At the current density, the OER overpotential and stabilization time of this catalyst are 190.5-220.6 mV and 48-50 h, respectively, which are far lower than the 310.6 mV overpotential of commercial RuO2 under the same conditions. Although the synthesis product of patent CN118792695B is the same as that of this invention, the chelating agent of the above patent does not use water-soluble polymers, the chelation rate is too slow, the heating procedure is complicated, and the preparation time of the precursor (the substance before entering the high temperature calcination) is too long.

[0006] Patent CN118792695A discloses a rapid preparation method for a multi-strain ruthenium-based pyrochlore catalyst. The method involves adding yttrium nitrate, ruthenium trichloride, and potassium citrate to deionized water and mixing thoroughly. Citric acid is then continuously added while stirring to adjust the pH of the solution to 3-5, resulting in a first mixed solution. This first mixed solution is reacted at 80-95℃ for 5-10 hours to obtain a gel. The gel is then vacuum-dried at 60-100℃ for 10-12 hours to obtain gel solid particles. These gel solid particles are mixed with potassium chloride and ground into powder. The powder is then placed in the groove of a graphite sample stage of a Joule heating device and subjected to Joule heat treatment in an air atmosphere. After washing and vacuum drying, the multi-strain ruthenium-based pyrochlore catalyst is obtained. The catalyst is then reacted in a 0.1M HClO4 aqueous solution at 10 mA·cm⁻¹. 2 At the current density, the OER overpotential and stabilization time of this catalyst are 190.5-220.6 mV and 48-50 h, respectively, which are far lower than the 310.6 mV overpotential of commercial RuO2 under the same conditions, indicating broad prospects for industrialization. Patent CN118792695A is similar to the product synthesized in this invention. However, the chelating agent in the above patent does not use water-soluble polymers and the precursor synthesis steps are different. The heating procedure is complex and the preparation time of the precursor (the substance before entering high-temperature calcination) is too long.

[0007] Traditional pyrochlore preparation often employs a high-temperature solid-state method, which involves mixing yttrium and ruthenium metal salts in a stoichiometric ratio and then calcining them at a specific high temperature for an extended period to obtain the product. However, this method has the following drawbacks: the distribution of metal salts is difficult to achieve uniformly, easily leading to the presence of impurities in the product and affecting material properties; during the preparation of the precursor, the precursor prepared using general chelating agents is relatively compact, with a small specific surface area and insufficient porosity; simple high-temperature heating procedures cannot achieve the optimal catalytic performance of Y₂Ru₂O₇, and excessively high temperatures result in high energy consumption, while excessively low temperatures easily lead to particle agglomeration. Summary of the Invention

[0008] To address the problems of uneven mixing and uneven product distribution in the traditional preparation of Y2Ru2O7, this invention provides the following technical solution: This invention provides a method for preparing Y2Ru2O7, the method of which is as follows: Ruthenium salt and yttrium salt are dissolved in water, and a water-soluble polymeric chelating agent is added and mixed evenly. The resulting mixture is evaporated to dryness at 120–140 °C (preferably 120 °C) to obtain a fluffy precursor. The fluffy precursor is heated to 600–700 °C (preferably 700 °C) and held for 6–8 h (preferably 6 h), then heated to 1000–1100 °C (preferably 1050 °C) and held for 12–18 h (preferably 12 h). After natural cooling, Y2Ru2O7 is obtained. The water-soluble polymeric chelating agent is polyvinylpyrrolidone, hydroxypropyl methylcellulose, polyacrylic acid, sodium polyacrylate, polymaleic acid, or polyvinylcaprolactam. The molar ratio of ruthenium salt to yttrium salt is 1:1, and the mass ratio of the water-soluble polymeric chelating agent to the ruthenium salt is 1–10:0.1307.

[0009] Furthermore, the ruthenium salt is RuCl3·3H2O.

[0010] Furthermore, the yttrium salt is Y(NO3)3·6H2O.

[0011] Furthermore, the water-soluble polymeric chelating agent is PVP (K12), PVP (K30), or HPMC.

[0012] Furthermore, the fluffy precursor is heated to 600-700 ℃ at a rate of 2-5 ℃ / min, and to 1000-1100 ℃ at a rate of 5-10 ℃ / min.

[0013] Furthermore, the volume of the water, in terms of the amount of ruthenium salt, is 100-160 L / mol.

[0014] Furthermore, the mass ratio of the water-soluble polymeric chelating agent to the ruthenium salt is 2:0.1307.

[0015] The beneficial effects of this invention are: By selecting a water-soluble polymer as a chelating agent, Y 3+ With Ru 3+ The ions react readily, resulting in high-purity products. XRD analysis reveals it to be a homogeneous Y₂Ru₂O₇ pyrochlore material. It exhibits good electrocatalytic performance as an OER catalyst, achieving good electrocatalytic activity at 10 mA cm⁻¹. - The oxygen evolution reaction (OER) overpotential at current density is 190-240 mV, and at 100 mA cm⁻¹ - ² The overpotential at current density is 350 mV; at 10 mA cm⁻¹ - It can operate stably for 22-30 hours at current density. Attached Figure Description

[0016] Figure 1 XRD patterns of Y2Ru2O7 synthesized in Examples 1, 2, and 3

[0017] Figure 2 XRD pattern of Example 1 compared with standard pyrochlore card

[0018] Figure 3 TEM image and lattice pattern of Example 1

[0019] Figure 4 : ISLV performance graph of Y2Ru2O7 in Example 1.

[0020] Figure 5 Stability test diagram of Example 1.

[0021] Figure 6 Diffraction rings of Example 2

[0022] Figure 7 LSV performance diagram of Example 2

[0023] Figure 8 Stability test of Example 2

[0024] Figure 9 Performance graph of LSV in Example 3 Detailed Implementation

[0025] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be considered as specific limitations of the invention.

[0026] Example 1

[0027] 1. Reagents and Instruments

[0028] Reagents: RuCl3·3H2O (Sinopharm Group), Y(NO3)3·6H2O (Aladdin Reagent), PVP K30 (Sigma-Aldrich), deionized water (self-made).

[0029] Instruments: Electronic analytical balance (accuracy 0.1 mg), magnetic stirrer, oil bath, corundum crucible, muffle furnace (Carbolite).

[0030] 2. Experimental Procedure

[0031] Weigh 0.1307 g (0.5 mmol) RuCl3·3H2O and 0.1915 g (0.5 mmol) Y(NO3)3·6H2O, add them to a beaker containing 80 mL of deionized water, and stir magnetically for 30 min until completely dissolved.

[0032] Add 2 g of PVP K30 to the solution and continue stirring for 10 min to obtain a black solution.

[0033] The beaker was placed in an oil bath at 130°C and evaporated to dryness under magnetic stirring. After about 5 hours, the water was completely evaporated, yielding a yellow, fluffy precursor.

[0034] - The precursor was transferred to a corundum crucible and placed in a muffle furnace. The temperature was increased to 700 °C at a rate of 5 °C / min and held for 6 h. Then the temperature was increased to 1050 °C at a rate of 10 °C / min and held for 12 h. After natural cooling, yttrium ruthenium pyrochlore product (Y2Ru2O7) was obtained.

[0035] XRD analysis was performed on Examples 1, 2, and 3 using a Bruker D8 Advance X-ray diffractometer. The results are as follows: Figure 1 As shown, the characteristic peak positions are matched, there is no shift, and no new impurity peaks, proving the purity of the phase; the absence of peak broadening and shift indicates good crystallinity and no lattice damage. Analysis of Example 1 using a Bruker D8 Advance X-ray diffractometer, and comparison with the PDF card, are shown in the following figures. Figure 2 As shown, its characteristic peak positions are matched, there is no shift, no new extraneous peaks, no peak broadening, and no shift.

[0036] The surface of the material in Example 1 was observed using a transmission electron microscope (TEM), and the results are as follows: Figure 3 As shown, a distinct pyrochlore lattice can be observed, indicating the successful formation of pyrochlore.

[0037] All electrochemical tests in this embodiment were performed using the same instrument: a Shanghai Chenhua CHI660E electrochemical workstation. All electrochemical tests employed a three-electrode system. The electrode system consisted of a working electrode (1 cm x 1 cm) with the pyrochlore electrocatalyst ink coated on carbon paper, prepared in this embodiment, as the working electrode; a Pt sheet as the counter electrode; and an Ag / AgCl reference electrode. The test electrolyte was 50 ml of 0.5 M H₂SO₄ strong acid solution. All potentials were uniformly calibrated to the reversible hydrogen electrode (RHE) potential, and OER and cp tests were performed. The pyrochlore electrocatalyst ink formulation consisted of 480 μL water, 480 μL ethanol, 20 μL nafion, 5 mg pyrochlore catalyst powder, and 2 mg Ketjen Black. The ink on the carbon paper was 10 μL. Four times, after drying with a heat lamp, linear sweep voltammetry (LSV) curves were performed. Figure 4 The LSV curve measured in Example 1 is shown in the figure. As can be seen from the figure, in Example 1, the LSV curve at 10 mA·cm⁻¹... -2 100mA·cm -2 These correspond to 1.42V and 1.57V respectively. The overpotential calculation formula yields the 10 mA·cm⁻¹ value for Example 1. -2 100mA·cm -2 The overpotentials correspond to 190 mA and 340 mA, respectively. Figure 5 The figure shows the stability test results for the embodiment. It can be seen that the stability is 22 hours.

[0038] Figure 1 The black curve in the middle is the XRD pattern of Y2Ru2O7 in this embodiment.

[0039] Figure 2 The XRD pattern of Y2Ru2O7 in this embodiment is compared with the standard.

[0040] Figure 3 The crystal lattice pattern of Y2Ru2O7 in this embodiment was captured by TEM.

[0041] Figure 4 This is the ISV diagram of Y2Ru2O7 in this embodiment.

[0042] Figure 5 This is the cp diagram of Y2Ru2O7 in this embodiment.

[0043] Example 2

[0044] 1. Reagents and Instruments

[0045] Reagents: RuCl3·3H2O (Sinopharm Group), Y(NO3)3·6H2O (Aladdin Reagent), PVP K12 (Sigma-Aldrich), deionized water (self-made).

[0046] Instruments: Electronic analytical balance (accuracy 0.1 mg), magnetic stirrer, oil bath, corundum crucible, muffle furnace (Carbolite).

[0047] 2. Experimental Procedure

[0048] Weigh 0.1307 g (0.5 mmol) RuCl3·3H2O and 0.1915 g (0.5 mmol) Y(NO3)3·6H2O, add them to a beaker containing 80 mL of deionized water, and stir magnetically for 30 min until completely dissolved.

[0049] Add 2 g of PVP K12 to the solution and continue stirring for 10 min to obtain a black solution.

[0050] The beaker was placed in an oil bath at 120°C and evaporated to dryness under magnetic stirring. After about 5 hours, the water was completely evaporated, yielding a yellow, fluffy precursor.

[0051] The precursor was transferred to a corundum crucible and placed in a muffle furnace. The temperature was increased to 600 °C at a rate of 5 °C / min and held for 6 h. Then, the temperature was increased to 1000 °C at a rate of 10 °C / min and held for 12 h. After natural cooling, yttrium ruthenium pyrochlore product (Y2Ru2O7) was obtained.

[0052] XRD analysis was performed on Examples 1, 2, and 3 using a Bruker D8 Advance X-ray diffractometer. The results are as follows: Figure 1 As shown, the characteristic peaks are matched in position, without shift or new impurity peaks, proving that the phase is pure; the absence of peak broadening and shift indicates that the crystallinity is intact and there is no lattice damage.

[0053] Diffraction ring analysis was performed on the surface of the material in Example 2 using transmission electron microscopy (TEM), and the results are as follows: Figure 6 As shown, only clear diffraction rings of pyrochlore indicate the formation of pyrochlore, and there are no other impurities.

[0054] All electrochemical tests in this embodiment were performed using the same instrument: a Shanghai Chenhua CHI660E electrochemical workstation. All electrochemical tests employed a three-electrode system. The electrode system consisted of a working electrode (1 cm x 1 cm) with the pyrochlore electrocatalyst ink coated on carbon paper, prepared in this embodiment, as the working electrode; a Pt sheet as the counter electrode; and an Ag / AgCl reference electrode. The test electrolyte was 50 ml of 0.5 M H₂SO₄ strong acid solution. All potentials were uniformly calibrated to the reversible hydrogen electrode (RHE) potential, and OER and cp tests were performed. The pyrochlore electrocatalyst ink formulation consisted of 480 μL water, 480 μL ethanol, 20 μL nafion, 5 mg pyrochlore catalyst powder, and 2 mg Ketjen Black. The ink on the carbon paper was 10 μL. Four times, after drying with a baking lamp, linear sweep voltammetry (LSV) curves were performed. Figure 7 The LSV curve measured in Example 2 is shown in the figure. According to the figure, the LSV of Example 2 at 10 mA·cm⁻¹ is... -2 100mA·cm -2 These correspond to 1.44V and 1.58V respectively. The overpotential of Example 2 can be calculated using the overpotential calculation formula: 10 mA·cm⁻¹ -2 100mA·cm -2 The overpotentials correspond to 210 mA and 350 mA, respectively. Figure 8 The stability test results for Example 2 are shown below. It can be seen that the stability is 30 hours.

[0055] Figure 1 The large red curve is the XRD pattern of Y2Ru2O7 in this embodiment.

[0056] Figure 6 This is the diffraction ring pattern of Y2Ru2O7 in this embodiment.

[0057] Figure 7 This is the ISV diagram of Y2Ru2O7 in this embodiment.

[0058] Figure 8 This is the cp diagram of Y2Ru2O7 in this embodiment.

[0059] Example 3

[0060] 1. Reagents and Instruments

[0061] Reagents: RuCl3·3H2O (Sinopharm Group), Y(NO3)3·6H2O (Aladdin Reagent), HPMC, deionized water (self-made).

[0062] - Instruments: Electronic analytical balance (accuracy 0.1 mg), magnetic stirrer, oil bath, corundum crucible, muffle furnace (Carbolite) 2. Experimental Procedure Weigh 0.1307 g (0.5 mmol) RuCl3·3H2O and 0.1915 g (0.5 mmol) Y(NO3)3·6H2O, add them to a beaker containing 80 mL of deionized water, and stir magnetically for 30 min until completely dissolved.

[0063] Add 2 g of HPMC to the solution and continue stirring for 10 min to obtain a black solution. Place the beaker in an oil bath at 140℃ and evaporate to dryness with magnetic stirring. After about 3 h, the water has completely evaporated, yielding a yellow, fluffy precursor.

[0064] The precursor was transferred to a corundum crucible and placed in a muffle furnace. The temperature was increased to 700 °C at a rate of 5 °C / min and held for 6 h. Then, the temperature was increased to 1050 °C at a rate of 10 °C / min and held for 12 h. After natural cooling, yttrium ruthenium pyrochlore product (Y2Ru2O7) was obtained.

[0065] XRD analysis was performed on Examples 1, 2, and 3 using a Bruker D8 Advance X-ray diffractometer. The results are as follows: Figure 1 As shown, the characteristic peak positions are matched, without shift or new impurity peaks, proving the purity of the phase; the absence of peak broadening and shift indicates good crystallinity and no lattice damage. All electrochemical tests in this embodiment used the same instrument: the Shanghai Chenhua CHI660E electrochemical workstation. All electrochemical tests employed a three-electrode system: the working electrode was the pyrochlore electrocatalyst ink coated on carbon paper prepared in this embodiment, with an immersion area of ​​1cm x 1cm in the electrolyte; the counter electrode was a Pt sheet; and the reference electrode was an Ag / AgCl reference electrode. The test electrolyte was 50 ml of 0.5 M H2SO4 strong acid solution. All potentials were uniformly calibrated to the reversible hydrogen electrode (RHE) potential, and OER and cp tests were performed. The pyrochlore electrocatalyst ink formulation consisted of 480 μL water, 480 μL ethanol, 20 μL nafion, 5 mg pyrochlore catalyst powder, and 2 mg Ketjen Black; the ink on the carbon paper was 10 μL. Four times, after drying with a heat lamp, linear sweep voltammetry (LSV) curves were performed. Figure 9 The LSV curve measured in Example 3 is shown in the figure. According to the figure, the LSV of Example 3 at 10 mA·cm⁻¹ is... -2 100mA·cm -2 These correspond to 1.47V and 1.58V respectively; the overpotential of real 3 can be calculated using the overpotential calculation formula as 10 mA·cm. -2 100mA·cm -2 The overpotentials correspond to 240 mA and 350 mA, respectively.

[0066] Figure 1 The pink curve represents the XRD pattern of Y2Ru2O7 in this embodiment.

[0067] Figure 9 This is the ISV spectrum of Y2Ru2O7 in this embodiment.

Claims

1. A method for preparing Y₂Ru₂O₇, characterized in that, The preparation method is as follows: Ruthenium salt and yttrium salt are dissolved in water, and a water-soluble polymeric chelating agent is added and mixed evenly. The resulting mixture is evaporated to dryness at 120–140 °C to obtain a fluffy precursor. The fluffy precursor is heated to 600–700 °C and held for 6–8 h, then heated to 1000–1100 °C and held for 12–18 h. After natural cooling, Y2Ru2O7 is obtained. The water-soluble polymeric chelating agent is polyvinylpyrrolidone, hydroxypropyl methylcellulose, polyacrylic acid, sodium polyacrylate, polymaleic acid, or polyvinylcaprolactam. The molar ratio of ruthenium salt to yttrium salt is 1:1, and the mass ratio of the water-soluble polymeric chelating agent to the ruthenium salt is 1–10:0.1307.

2. The method for preparing Y₂Ru₂O₇ as described in claim 1, characterized in that, The ruthenium salt mentioned is RuCl3·3H2O.

3. The method for preparing Y₂Ru₂O₇ as described in claim 1, characterized in that, The yttrium salt is Y(NO3)3·6H2O.

4. The method for preparing Y₂Ru₂O₇ as described in claim 1, characterized in that, The water-soluble polymeric chelating agent is PVP (K12), PVP (K30), or HPMC.

5. The method for preparing Y₂Ru₂O₇ as described in claim 1, characterized in that, The fluffy precursor is heated to 600-700 ℃ at a rate of 2-5 ℃ / min, and to 1000-1100 ℃ at a rate of 5-10 ℃ / min.

6. The method for preparing Y₂Ru₂O₇ as described in claim 1, characterized in that, The volume of water, in terms of the amount of ruthenium salt, is 100-160 L / mol.

7. The method for preparing Y₂Ru₂O₇ as described in claim 1, characterized in that, The mass ratio of the water-soluble polymeric chelating agent to the ruthenium salt is 2:0.1307.

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