Preparation and application of mixed high-valence tungsten oxide supported Ir-based catalyst
By grinding low-temperature molten salt and room temperature, a mixed high-valent tungsten oxide supported Ir-based catalyst was prepared, which solved the problem of insufficient activity and stability of existing catalysts under high oxidation potential, and achieved more efficient acid oxygen evolution reaction performance and stability.
Patent Information
- Application Number
- CN202510650478.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-20
- Publication Date
- 2025-06-27
AI Technical Summary
The existing acidic oxygen evolution reaction (OER) catalysts have problems with excessive oxidation and dissolution at high oxidation potentials, resulting in insufficient catalyst activity and stability, and the small specific surface area of the support, which hinders the effective contact between the Ir active site and the electrolyte.
The strategy of combining low-temperature molten salt with room temperature grinding is adopted to prepare a mixed high-valent tungsten oxide-supported Ir-based catalyst to achieve stable construction of elemental iridium on the surface of porous tungsten oxide, and improve the intrinsic oxygen analysis activity of the catalyst and the stability under high potential.
The acidic OER performance and high potential stability of the catalyst are significantly improved, which is better than the elemental Ir, and the use of small content and smaller size Ir active sites can contact the electrolyte more effectively.
Smart Images
Figure CN120210853A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalysts, and particularly relates to the preparation and application of a mixed high-valence tungsten oxide supported Ir-based catalyst. Background Art
[0002] Proton exchange membrane water electrolysis (PEMWE) is an efficient water electrolysis hydrogen production technology. Its working principle is to carry out hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on both sides of the proton exchange membrane respectively. Under acidic conditions, water molecules undergo oxygen evolution reaction at the anode to generate oxygen and hydrogen ions. The hydrogen ions further migrate through the proton exchange membrane to the cathode and obtain electrons to generate hydrogen at the cathode.
[0003] The performance of the acidic oxygen evolution reaction (OER) directly affects the hydrogen production efficiency, energy consumption and stability of proton exchange membrane water electrolysis (PEMWE), and is one of the key links in the development of proton exchange membrane water electrolysis (PEMWE) technology. Therefore, the research and development of acidic oxygen evolution reaction (OER) catalysts is crucial for hydrogen production by proton exchange membrane water electrolysis (PEMWE). Currently, the commercial OER catalysts are mainly pure iridium (Ir) or pure iridium oxide (IrO2), with a large usage amount, but the reserves of Ir are scarce and the price is expensive. Therefore, loading iridium on a support can effectively reduce the content of precious metals used on the one hand, and further improve the activity-stability of the catalyst on the other hand.
[0004] Currently, researchers often use carriers that are acid-stable and have a certain inertness to load precious metal iridium, such as titanium dioxide, manganese dioxide, etc. These carriers have poor conductivity and a single valence state, which hinders the effective transfer of charge from the external circuit to the Ir sites. At the same time, it is difficult to inhibit the over-oxidation and dissolution of Ir at high oxidation potentials, resulting in the catalyst can only operate in a low potential range. In addition, the specific surface areas of these carriers are relatively small, and there is still a large room for improvement to promote more direct contact between Ir active sites and the electrolyte, thereby improving the acidic OER performance of the catalyst.
[0005] Therefore, there is a need in the art to develop a preparation and application of a mixed high-valence oxide supported Ir-based catalyst that can effectively solve the above problems. Summary of the Invention
[0006] The purpose of the present invention is to provide a preparation and application of a mixed high-valence tungsten oxide supported Ir-based catalyst. This preparation adopts a strategy combining low-temperature molten salt and room-temperature grinding to achieve the stable construction of elemental iridium on the surface of mixed high-valence tungsten oxide, and improves the intrinsic oxygen evolution activity of the prepared catalyst and its stability at high operating potentials.
[0007] To achieve the above purpose, the present invention provides a preparation of a mixed high-valence tungsten oxide supported Ir-based catalyst, including the following steps: Step S1: Synthesize porous tungsten oxide by the molten salt method; Step S2: Prepare a mixed high-valence tungsten oxide supported Ir-based catalyst.
[0008] Preferably, step S1 is specifically as follows: Step S11: Weigh tungsten hexachloride, sodium hydroxide, sodium nitrate, and potassium chloride. Mix the weighed tungsten hexachloride, sodium hydroxide, sodium nitrate, and potassium chloride and place them in a porcelain boat to obtain a mixture; Step S12: Calcinate the mixture; Step S13: After the calcination is completed and the temperature is reduced to room temperature, obtain a sample and rinse the sample with hydrochloric acid with a concentration of 20 wt%; Step S14: Calcinate the rinsed sample in an air atmosphere to prepare porous tungsten oxide.
[0009] Preferably, in step S11, the weighed amounts are as follows: 0.74 - 0.84 g of tungsten hexachloride, 0.64 - 0.74 g of sodium nitrate, 0.18 - 0.28 g of potassium chloride, and 0.11 - 0.21 g of sodium hydroxide.
[0010] Preferably, in step S12, the calcination temperature is 360 - 400 o °C, and the calcination time is 1 - 3 h.
[0011] Preferably, step S14 is specifically as follows: a. Calcinate the rinsed sample in an air atmosphere at a temperature of 150 °C for 8 h; b. And continue to calcinate in an air atmosphere at a temperature of 550 °C for 3 h; finally, the sample is in a crystalline state in the crucible; c. Soak the crystalline sample with hydrochloric acid with a molar concentration of 0.5 mol / L for 24 h, filter, dry, and grind to obtain a powder, which is the porous tungsten oxide.
[0012] Preferably, step S2 is specifically as follows: Step S21: Weigh iridium chloride, porous tungsten oxide, sodium borohydride, potassium hydroxide, and sodium chloride, mix them and place them in a mortar to obtain a mixture; Step S22: Grind the mixture at room temperature for 10 - 40 min to prepare a mixed high-valence tungsten oxide supported Ir-based catalyst.
[0013] Preferably, in step S21, the weighed amounts are as follows: 0.03 - 0.08 g of iridium chloride, 0.06 - 0.11 g of porous tungsten oxide, 0.03 - 0.08 g of sodium borohydride, 0.005 - 0.055 g of potassium hydroxide, and 0.005 - 0.055 g of sodium chloride.
[0014] Application of a catalyst prepared by a hybrid high-valence tungsten oxide-supported Ir-based catalyst in proton exchange membrane water electrolysis for hydrogen production in acidic oxygen evolution reaction.
[0015] The present invention adopts the preparation and application of the above-mentioned hybrid high-valence tungsten oxide-supported Ir-based catalyst, and the beneficial effects are as follows: (1) Most of the iridium oxides are loaded on the surface of the existing carrier oxides, while the iridium (Ir) in this invention is a highly active single element; the present invention adopts a strategy combining low-temperature molten salt and room-temperature grinding, which helps to uniformly construct a high specific surface area type catalyst, and then realizes the stable construction of highly active single iridium on the surface of hybrid high-valence tungsten oxide; and the size of iridium is small, 3-5 nanometers, and the usage content is small; the prepared porous tungsten oxide carrier, because tungsten oxide is a porous structure, provides a higher specific surface area for the loading of iridium; further, it can promote more active sites to be exposed in the electrolyte, and the catalytic activity can be greatly improved; (2) On the one hand, the multivalent tungsten oxide in this invention can promote the charge transfer from the carrier to the Ir site and improve the reaction activity; on the other hand, most of the existing carrier oxides are of a single valence state and relatively low valence state, making it difficult to inhibit the increase of the Ir valence state during the reaction; while the high-valence W in this invention can form a W-O-Ir asymmetric catalytic structure with Ir, promoting the transfer of electrons on the O surface to Ir, stabilizing the Ir valence state, improving the antioxidant property of the prepared catalyst, and ensuring that Ir is in a relatively low valence state (less than +4 valence) throughout the reaction process, and the high-potential stability of the catalyst is greatly improved; (3) The hybrid high-valence tungsten oxide-supported Ir-based catalyst prepared by the present invention maintains high activity and high stability in acidic electrolyzed water, and can show a low overpotential of 255 mV at a current density of 10 mA cm -2 and has a stability of more than 20 h, and its performance is better than that of single Ir.
[0016] The technical solution of the present invention will be further described in detail below through the accompanying drawings and embodiments. Description of the Drawings
[0017] Figure 1 XRD and EPR comparison diagrams of Ir@MWO and M-WO3 prepared in the preparation and application examples of a hybrid high-valence tungsten oxide-supported Ir-based catalyst of the present invention; among them, (a) is the XRD comparison diagram and (b) is the EPR comparison diagram; Figure 2 SEM and HRTEM diagrams of the Ir@MWO catalyst prepared in the preparation and application examples of a hybrid high-valence tungsten oxide-supported Ir-based catalyst of the present invention; among them, (a) is the SEM diagram and (b) is the HRTEM diagram; Figure 3XPS valence state analysis diagrams of Ir@MWO and M-WO3 prepared in an embodiment of the preparation and application of a hybrid high-valence tungsten oxide-supported Ir-based catalyst of the present invention; among them, (a) is the W 4f energy spectrum diagram, and (b) is the Ir 4f energy spectrum diagram; Figure 4 Performance comparison diagram of Ir@MWO prepared in an embodiment of the preparation and application of a hybrid high-valence tungsten oxide-supported Ir-based catalyst of the present invention; among them, (a) is the linear sweep voltammogram of Ir@MWO and elemental iridium (Ir), and (b) is the comparison diagram of the stability test of the chronoamperometric curve of Ir@MWO and elemental iridium (Ir). Detailed implementation manners
[0018] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0019] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.
[0020] The preparation of a hybrid high-valence tungsten oxide-supported Ir-based catalyst includes the following steps: Step S1: Synthesize porous tungsten oxide by the molten salt method.
[0021] Step S11: Weigh 0.74 - 0.84 g of tungsten hexachloride, 0.64 - 0.74 g of sodium nitrate, 0.18 - 0.28 g of potassium chloride, and 0.11 - 0.21 g of sodium hydroxide. Mix the weighed tungsten hexachloride (WCl6), sodium hydroxide (NaOH), sodium nitrate (NaNO3), and potassium chloride (KCl) and place them in a porcelain boat to obtain a mixture.
[0022] Step S12: Calcinate the mixture at 360 - 400 °C for 1 - 3 h.
[0023] Step S13: After the calcination is completed and cooled to room temperature, obtain the sample and rinse the sample with hydrochloric acid (HCl) with a concentration of 20 wt%.
[0024] Step S14: Calcinate the rinsed sample in an air atmosphere to obtain porous tungsten oxide.
[0025] a. Calcinate the rinsed sample in an air atmosphere at a temperature of 150 °C for 8 h.
[0026] b. And continue to calcinate in an air atmosphere at a temperature of 550 °C for 3 h. Finally, the sample is in a crystalline state in the crucible.
[0027] c. Soak the crystalline sample in hydrochloric acid with a molar concentration of 0.5 mol / L for 24 h, filter, dry, and grind to obtain a powder, which is the porous tungsten oxide.
[0028] Step S2: Prepare a mixed high-valence tungsten oxide supported Ir-based catalyst.
[0029] Step S21: Weigh 0.03 - 0.08 g of iridium chloride, 0.06 - 0.11 g of porous tungsten oxide, 0.03 - 0.08 g of sodium borohydride, 0.005 - 0.055 g of potassium hydroxide, and 0.005 - 0.055 g of sodium chloride. Mix the weighed iridium chloride, porous tungsten oxide, sodium borohydride (NaBH4), potassium hydroxide (KOH), and sodium chloride and place them in a mortar to obtain a mixture.
[0030] Step S22: At room temperature, mill the mixture for 10 - 40 min to obtain the mixed high-valence tungsten oxide supported Ir-based catalyst.
[0031] The room temperature milling method is used to load elemental iridium on the surface of porous tungsten oxide, and at the same time, partial reduction of the tungsten valence state is achieved to form a mixed high-valence tungsten oxide support. Example
[0032] The preparation of a mixed high-valence tungsten oxide supported Ir-based catalyst includes the following steps: Step S1: Synthesize porous tungsten oxide by the molten salt method.
[0033] Step S11: Weigh 0.79 g of tungsten hexachloride, 0.69 g of sodium nitrate, 0.23 g of potassium chloride, and 0.16 g of sodium hydroxide. Mix the weighed tungsten hexachloride, sodium hydroxide, sodium nitrate, and potassium chloride and place them in a porcelain boat to obtain a mixture.
[0034] Step S12: Calcine the mixture at 360 o °C for 2.5 hours.
[0035] Step S13: After the calcination is completed and the temperature is reduced to room temperature, obtain the sample and rinse the sample with hydrochloric acid with a concentration of 20 wt%.
[0036] Step S14: Calcine the rinsed sample in an air atmosphere to obtain porous tungsten oxide (M-WO3).
[0037] a. Calcine the rinsed sample in an air atmosphere at a temperature of 150 °C for 8 h.
[0038] b. And continue to calcine in an air atmosphere at a temperature of 550 °C for 3 h. Finally, the sample is in a crystalline state in the crucible.
[0039] c. Immerse the crystalline sample in hydrochloric acid with a molar concentration of 0.5 mol / L for 24 h, filter, dry, and grind to obtain a powder, which is porous tungsten oxide (M-WO3).
[0040] Step S2: Prepare a mixed high-valence tungsten oxide supported Ir-based catalyst.
[0041] Step S21: Weigh 0.03 g of iridium chloride, 0.06 g of porous tungsten oxide, 0.03 g of sodium borohydride, 0.005 g of potassium hydroxide, and 0.005 g of sodium chloride. Mix the weighed iridium chloride, porous tungsten oxide, sodium borohydride, potassium hydroxide, and sodium chloride and place them in a mortar to obtain a mixture.
[0042] Step S22: At room temperature, mill the mixture for 30 minutes to obtain a mixed high-valence tungsten oxide supported Ir-based catalyst (Ir@MWO).
[0043] Test the porous tungsten oxide (M-WO3), mixed high-valence tungsten oxide supported Ir-based catalyst (Ir@MWO), and elemental iridium (Ir) prepared in this example.
[0044] (1) As Figure 1 shown, elemental Ir in this example was synthesized on the surface of the support, and tungsten oxide was reduced to an amorphous state; EPR showed that the content of oxygen vacancies inside tungsten oxide increased after loading Ir, which corresponded to the decrease in the W valence state.
[0045] (2) As Figure 2 shown, the mixed high-valence tungsten oxide supported Ir-based catalyst (Ir@MWO) prepared in this example has a high dispersion and small size.
[0046] (3) As Figure 3 shown, the valence state of tungsten in this example decreased after loading Ir, being a mixed valence state of +6, +5, and +4. And Ir showed a small increase in valence state due to contact with tungsten oxide, but most of it was still in the 0 valence state, i.e., the elemental state.
[0047] (4) As Figure 4 shown, the mixed high-valence tungsten oxide supported Ir-based catalyst (Ir@MWO) prepared in this example has excellent performance, superior to elemental iridium (Ir).
[0048] Therefore, the present invention adopts the preparation and application of the above-mentioned mixed high-valence tungsten oxide supported Ir-based catalyst. This preparation adopts a strategy combining low-temperature molten salt and room-temperature grinding, realizing the stable construction of elemental iridium on the surface of mixed high-valence tungsten oxide, and improving the intrinsic oxygen evolution activity of the prepared catalyst and its stability at high operating potentials.
[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements do not enable the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A preparation method of a mixed high-valent tungsten oxide supported Ir-based catalyst, characterized in that: The following steps are involved: Step S1, synthesizing porous tungsten oxide by molten salt method; Step S2, preparing a mixed high-valent tungsten oxide-supported Ir-based catalyst.
2. The preparation of a mixed high-valent tungsten oxide supported Ir-based catalyst according to claim 1, characterized in that: Step S1 is specifically as follows: Step S11, weighing tungsten hexachloride, sodium hydroxide, sodium nitrate, and potassium chloride, mixing the weighed tungsten hexachloride, sodium hydroxide, sodium nitrate, and potassium chloride, and placing the mixed mixture in a porcelain boat to obtain a mixture; Step S12, calcining the mixture; Step S13, after the calcination is completed and the temperature is lowered to room temperature, a sample is obtained, and the sample is washed with hydrochloric acid having a concentration of 20 wt%; Step S14: calcining the rinsed sample in an air atmosphere to obtain porous tungsten oxide.
3. The preparation of a mixed high-valent tungsten oxide supported Ir-based catalyst according to claim 2, characterized in that: In step S11, the weighed amounts are 0.74-0.84 g of tungsten hexachloride, 0.64-0.74 g of sodium nitrate, 0.18-0.28 g of potassium chloride, and 0.11-0.21 g of sodium hydroxide.
4. The preparation of a mixed high-valent tungsten oxide supported Ir-based catalyst according to claim 2, characterized in that: In step S12, the calcination temperature is 360-400 o C, calcination time is 1-3h.
5. The preparation of a mixed high-valent tungsten oxide supported Ir-based catalyst according to claim 2, characterized in that: Step S14 is specifically as follows: a. Calcine the rinsed sample in air atmosphere at 150°C for 8h; b. Continue to calcine at 550°C for 3h in air atmosphere; finally, the sample is in a crystalline state in the crucible; c. Soak the crystalline sample in 0.5 mol / L hydrochloric acid for 24 hours, filter, dry and grind to obtain a powder, which is porous tungsten oxide.
6. The preparation of a mixed high-valent tungsten oxide supported Ir-based catalyst according to claim 1, characterized in that: Step S2 is specifically as follows: Step S21, weighing iridium chloride, porous tungsten oxide, sodium borohydride, potassium hydroxide, and sodium chloride, mixing and placing in a mortar to obtain a mixture; Step S22: Grind the mixture for 10-40 minutes at room temperature to obtain a mixed high-valent tungsten oxide-supported Ir-based catalyst.
7. The preparation of a mixed high-valent tungsten oxide supported Ir-based catalyst according to claim 6, characterized in that: In step S21, the weighed amounts are respectively: iridium chloride 0.03-0.08 g, porous tungsten oxide 0.06-0.11 g, sodium borohydride 0.03-0.08 g, potassium hydroxide 0.005-0.055 g, and sodium chloride 0.005-0.055 g.
8. Use of a catalyst prepared from the mixed high-valent tungsten oxide-supported Ir-based catalyst as claimed in any one of claims 1 to 7 in proton exchange membrane water electrolysis for hydrogen production in an acidic oxygen evolution reaction.