Iridium-based supported catalysts, methods for their preparation and use
By forming an iridium oxide shell on the surface of titanium dioxide, the problem of excessive iridium catalyst loading was solved, the conductivity and water electrolysis efficiency were improved, and the efficient application of iridium-based supported catalysts was realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TSINGHUA UNIVERSITY
- Filing Date
- 2024-08-19
- Publication Date
- 2026-04-28
AI Technical Summary
In existing PEM water electrolysis processes, the loading of iridium catalyst cannot meet actual requirements, resulting in poor conductivity, high ohmic loss, and affecting the efficiency of water electrolysis.
By forming an iridium oxide shell on the surface of titanium dioxide, a uniform core-shell structure is formed, reducing the iridium loading and improving the conductivity of the catalyst. An iridium oxide coating layer is formed in situ on the titanium dioxide support by alkaline hydrolysis and oxidation reaction.
This approach achieves a reduction in iridium loading and an improvement in catalytic performance, forming a good electronic conductivity network, which enhances the electrolysis performance of PEM water electrolysis and the lifespan of the catalyst.
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Figure CN118957635B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to an iridium-based supported catalyst and its preparation method, as well as the application of proton exchange membrane electrolysis water membrane electrode and iridium-based catalyst. Background Technology
[0002] Hydrogen energy is an indispensable energy carrier due to its high energy density and zero carbon emissions. Currently, PEM (proton exchange membrane) water electrolysis and alkaline water electrolysis coupled with photovoltaic or wind power are promising green hydrogen production methods. PEM water electrolysis has attracted much attention due to its high current density, high energy conversion efficiency, high hydrogen purity, and high responsiveness. However, in the PEM water electrolysis process, the anode requires a high potential to drive the reaction due to the slow reaction kinetics of the oxygen evolution reaction (OER), which reduces the energy conversion efficiency of the PEM electrolyzer. Under the harsh operating conditions of the anode (high potential, pure oxygen environment, and high acidity), iridium catalysts have become the mainstream commercial catalysts for PEM water electrolysis due to their excellent stability and catalytic activity.
[0003] Currently, the power density per unit mass of iridium cannot meet practical requirements. Therefore, reducing the iridium loading in the catalyst layer and improving iridium utilization are crucial for the large-scale application of PEMWE (Proton Exchange Membrane Water Electrolysis). However, currently, all prepared supported catalysts are iridium-based catalysts distributed on a support, requiring a high loading to improve their conductivity and thus enhance catalytic performance. This contradicts the initial intention of reducing iridium loading. Furthermore, low-iridium catalysts have poor conductivity and exhibit high ohmic losses in PEMWE. Summary of the Invention
[0004] This invention aims to at least partially solve the technical problem of reducing iridium loading while maintaining high catalytic performance. To this end, one objective of this invention is to provide an iridium-based supported catalyst and its preparation method, as well as the application of the proton exchange membrane electrolysis water electrode and the iridium-based catalyst. In this catalyst, iridium oxide uniformly forms a shell structure on the surface of titanium dioxide, effectively maintaining high catalytic performance and reducing iridium loading.
[0005] The first aspect of this application provides a method for preparing an iridium-based supported catalyst. According to an embodiment of the invention, the method includes: using titanium dioxide as a support, hydrolyzing an iridium precursor with an alkaline substance, then oxidizing the hydrolysis product with hydrogen peroxide to obtain a precursor for the iridium-based supported catalyst; and calcining the precursor in an oxygen atmosphere to prepare an iridium-based supported catalyst IrO. x@TiO2, where x = 1~2, IrO x It acts as a shell covering the surface of the TiO2 core.
[0006] This application utilizes alkaline hydrolysis, oxidation, and re-oxidation to form an iridium oxide coating layer on the surface of a titanium dioxide support through in-situ reaction. The iridium oxide uniformly coats the titanium dioxide surface at a nanometer thickness, forming a fully covered, continuous supported catalyst. This facilitates the formation of a good electronic conductivity network and improves the catalyst's conductivity. Simultaneously, the supported catalyst formed through this in-situ reaction exhibits high catalytic performance while reducing the iridium loading, thus balancing the iridium content and catalytic performance of the supported catalyst.
[0007] According to embodiments of the present invention, the preparation method of the above-mentioned iridium-based supported catalyst may further include at least one of the following additional technical features:
[0008] In some embodiments, the raw materials satisfy at least one of the following (1) to (3):
[0009] (1) The precursors of iridium include at least one of IrCl3, Na3IrCl6, Na2IrCl6 and H2IrCl6;
[0010] (2) Alkaline substances include at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate and lithium carbonate;
[0011] (3) The morphology of titanium dioxide includes at least one of titanium dioxide nanoparticles, titanium dioxide nanowires and titanium dioxide nanorods.
[0012] In some implementations, during the hydrolysis reaction step, the pH value is controlled to be 9–13.
[0013] In some embodiments, the control parameters in the calcination step are: calcination temperature of 250℃ to 450℃; and / or calcination time of 0.5h to 2h.
[0014] In some embodiments, the molar mass ratio of iridium atoms to hydrogen peroxide in the iridium precursor is 1:20 to 1:1000; and / or, the molar mass ratio of iridium atoms to titanium dioxide in the iridium precursor is 1:1 to 1:10.
[0015] In some embodiments, the hydrolysis reaction and the oxidation reaction include the steps of:
[0016] Prepare an aqueous solution of the iridium precursor;
[0017] Titanium dioxide was added to the aqueous solution to prepare a dispersion;
[0018] An alkaline substance is added to the dispersion to initiate a hydrolysis reaction;
[0019] Hydrogen peroxide is added to the hydrolysis reaction system to carry out an oxidation reaction.
[0020] A second aspect of this application provides an iridium-based supported catalyst. According to an embodiment of the invention, the iridium-based supported catalyst includes a core and a shell covering the core; the core comprises TiO2, and the shell comprises IrO. x , where x = 1 to 2.
[0021] The iridium-based supported catalyst IrO provided in this application x @TiO2 is a core-shell structure in which iridium oxide is uniformly coated on the surface of titanium dioxide, and the value of x is 1 to 2, that is, the iridium oxide can be a multivalent iridium oxide. This catalyst can effectively reduce the iridium loading and has high conductivity and catalytic performance.
[0022] In some embodiments, the iridium-based supported catalyst is prepared using the above-described preparation method, IrO x The mass percentage content is 20% to 75%.
[0023] A third aspect of this application provides a proton exchange membrane electrolysis water membrane electrode, comprising an iridium-based supported catalyst obtained by the above preparation method, or comprising the above-described iridium-based supported catalyst.
[0024] The iridium-based catalyst IrO provided in this application x @TiO2, with an iridium oxide shell fully covering the surface of titanium dioxide and only a few nanometers thick, effectively reduces the iridium loading and increases its catalytic performance. This core-shell catalyst exhibits excellent oxygen evolution performance and excellent electrolysis performance in PEM water electrolysis.
[0025] The fourth aspect of this application provides the application of an iridium-based supported catalyst in the water electrolysis reaction, wherein the iridium-based supported catalyst is the iridium-based supported catalyst obtained by the above preparation method, or is the iridium-based supported catalyst described above.
[0026] The iridium-based catalyst IrO provided in this application x @TiO2 exhibits excellent electrolytic performance in PEM water electrolysis.
[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0029] Figure 1 It is the 40% IrO provided in Embodiment 1 of this application. x Elemental mapping diagram of the @TiO2-NP catalyst.
[0030] Figure 2 It is the 40% IrO provided in Embodiment 1 of this application. x Elemental mapping diagram of the @TiO2-NR catalyst.
[0031] Figure 3 This is the 20% IrO provided in Embodiment 2 of this application. x Elemental mapping diagram of the @TiO2-NW catalyst.
[0032] Figure 4 It is the 40% IrO provided in Embodiment 1 of this application. x Figure showing the elemental content test results of the @TiO2-NP catalyst.
[0033] Figure 5 It is the 40% IrO provided in Embodiment 1 of this application. x The elemental content test results of the @TiO2-NR catalyst are shown in the figure.
[0034] Figure 6 This is the 20% IrO provided in Embodiment 2 of this application. x Figure showing the elemental content test results of the @TiO2-NW catalyst.
[0035] Figure 7 This is a graph showing the OER performance test results of the catalyst provided in the embodiments of this application.
[0036] Figure 8 This application includes a schematic diagram of the electrolysis water performance test structure.
[0037] Figure 9 This is a graph showing the test results of the electrolysis performance of the catalyst provided in the embodiments of this application. Detailed Implementation
[0038] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0039] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0040] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0041] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.
[0042] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.
[0043] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.
[0044] The first aspect of this application provides a method for preparing an iridium-based supported catalyst, comprising: using titanium dioxide as a support, hydrolyzing an iridium precursor with an alkaline substance, and then oxidizing the hydrolysis product with hydrogen peroxide to obtain a precursor of the iridium-based supported catalyst; calcining the precursor of the iridium-based supported catalyst in an oxygen atmosphere to prepare an iridium-based supported catalyst IrO. x @TiO2, where x = 1~2, IrO x It acts as a shell covering the surface of the TiO2 core.
[0045] Currently, reducing iridium loading is generally achieved through two methods: using iridium-based nanowire catalysts and preparing catalysts with iridium supported on a support. For iridium-based nanowire catalysts, the preparation process is complex and difficult to mass-produce. Using a support to prepare iridium-based catalysts can improve the dispersion of iridium metal and increase the number of reaction sites. Titanium dioxide is a widely available and highly stable support, widely reported in academia and industry; however, titanium dioxide is a near-insulating support, requiring a high iridium content to improve its conductivity, making it difficult to achieve high conductivity while reducing iridium content. Furthermore, current supported catalysts almost all involve iridium-based nanoparticles dispersed on a support. PEMWE electrolysis is a process involving electrons, protons, water, and oxygen, making a good conductive network crucial for the OER reaction. Current dispersed supported catalysts, due to the discontinuity of iridium dioxide, cannot construct a conductive electron network, which severely affects water electrolysis efficiency and catalyst lifespan.
[0046] This application utilizes alkaline hydrolysis, oxidation, and high-temperature calcination to prepare an iridium oxide coating layer in situ on the surface of a titanium dioxide support. The iridium oxide uniformly coats the titanium dioxide surface at a nanometer thickness, forming a fully covered, continuous supported catalyst. This facilitates the formation of a good electronic conductivity network and improves the catalyst's conductivity. Simultaneously, the supported catalyst formed through in-situ reaction in this application exhibits high catalytic performance while reducing the iridium loading, thus balancing the iridium content and catalytic performance of the supported catalyst.
[0047] This application prepares iridium hydroxide from the iridium precursor through alkaline hydrolysis; then, through the oxidation of hydrogen peroxide, the iridium hydroxide is oxidized to iridium oxide; finally, through calcination, some or all of the low-valence iridium oxide is further oxidized to become higher-valence iridium oxide, which also facilitates the uniform distribution of iridium oxide on the surface of titanium dioxide, effectively achieving a balance between catalytic performance and loading.
[0048] In some embodiments, the raw materials satisfy at least one of the following (1) to (3):
[0049] (1) The precursors of iridium include at least one of IrCl3, Na3IrCl6, Na2IrCl6 and H2IrCl6;
[0050] (2) Alkaline substances include at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate and lithium carbonate;
[0051] (3) The morphology of titanium dioxide includes at least one of titanium dioxide nanoparticles, titanium dioxide nanowires and titanium dioxide nanorods.
[0052] In this embodiment, the iridium precursor includes at least one of IrCl3, Na3IrCl6, Na2IrCl6 and H2IrCl6, which is soluble in an aqueous solvent and undergoes a hydrolysis reaction in full contact with the added alkaline substance, thereby improving the reaction efficiency.
[0053] Furthermore, the precursor of iridium is at least one of IrCl3 and H2IrCl6.
[0054] In this embodiment, the alkaline substance is used to provide an alkaline environment to promote the hydrolysis reaction of the iridium precursor. The alkaline substance includes at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, and lithium carbonate, which is beneficial for pH control and has a low cost.
[0055] Furthermore, alkaline substances include at least one of sodium hydroxide and potassium hydroxide.
[0056] In the embodiments of this application, the morphology of titanium dioxide includes at least one of titanium dioxide nanoparticles, titanium dioxide nanowires, and titanium dioxide nanorods.
[0057] Furthermore, the morphology of titanium dioxide is titanium dioxide nanoparticles.
[0058] In some embodiments, the raw materials satisfy the following conditions: the iridium precursor includes at least one of IrCl3, Na3IrCl6, Na2IrCl6 and H2IrCl6; the alkaline substance includes at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate and lithium carbonate; and the morphology of titanium dioxide includes at least one of titanium dioxide nanoparticles, titanium dioxide nanowires and titanium dioxide nanorods.
[0059] In some implementations, during the hydrolysis reaction step, the pH value is controlled to be 9–13.
[0060] In this embodiment, the pH value of the alkaline hydrolysis reaction is controlled between 9 and 13, which is conducive to promoting the hydrolysis reaction of the iridium precursor. Within a reasonable range, the higher the pH value, the more favorable the hydrolysis reaction becomes, and the better it is for the subsequent oxidation to form a higher purity iridium oxide. If the pH value is too low, the hydrolysis reaction will not occur, resulting in the inability to form a high purity iridium oxide during the subsequent oxidation and re-oxidation processes, thereby reducing the loading of iridium oxide. If the pH value is too high, it is a strongly alkaline environment, which is conducive to the hydrolysis reaction, but places higher demands on the reaction operation and equipment.
[0061] In a specific example, during the hydrolysis reaction steps, the pH value is controlled to be 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, or 13, etc.
[0062] Furthermore, in the hydrolysis reaction step, the pH value is controlled to be 9-10.
[0063] In some embodiments, the control parameters in the calcination step are: calcination temperature of 250℃ to 450℃; and / or calcination time of 0.5h to 2h.
[0064] In this embodiment, the precursor of the iridium-based supported catalyst is calcined in an oxygen atmosphere to further oxidize the low-valence iridium oxide, generating a higher-valence iridium oxide. By appropriately setting the calcination temperature, it is beneficial for the low-valence iridium to be oxidized to the high-valence iridium, forming a higher-valence iridium oxide, i.e., the iridium-based supported catalyst IrO. x In TiO2, the value of x increases to avoid the formation of other impurities and to form a high-purity iridium oxide shell structure. Specific examples show calcination temperatures of 250℃, 280℃, 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, and 450℃, and calcination times of 0.5h, 1h, 1.5h, and 2.0h.
[0065] In the embodiments of this application, the calcination temperature is 250℃~450℃, which is beneficial to improve the durability of the catalyst and at the same time helps to avoid the increase of crystallinity and the decrease of activity.
[0066] Furthermore, in the calcination process, the control parameters satisfy the following: the calcination temperature is 300℃~400℃.
[0067] In some embodiments, the molar mass ratio of iridium atoms to hydrogen peroxide in the iridium precursor is 1:20 to 1:1000; and / or, the molar mass ratio of iridium atoms to titanium dioxide in the iridium precursor is 1:1 to 1:10.
[0068] In this embodiment of the application, the molar mass ratio of iridium atoms to hydrogen peroxide in the iridium precursor is set to 1:20 to 1:1000. Specifically, the molar mass ratio of iridium atoms to hydrogen peroxide in the iridium precursor is set to 1:20, 1:50, 1:100, 1:200, 1:250, 1:300, 1:350, 1:400, 1:450, 1:500, 1:550, 1:600, 1:650, 1:700, 1:750, 1:800, 1:850, 1:900, 1:950, or 1:1000, etc.
[0069] In this embodiment, the combination of iridium atoms and hydrogen peroxide is reasonably set to ensure that the hydrolysis reaction products are fully oxidized and improve the product conversion rate.
[0070] In this embodiment of the application, the molar mass ratio of iridium atoms to titanium dioxide in the iridium precursor is set to 1:1 to 1:10. In specific examples, the molar mass ratio of iridium atoms to titanium dioxide in the iridium precursor is 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10, etc.
[0071] In this application, the molar mass ratio of iridium atoms to titanium dioxide in the iridium precursor is reasonably set to ensure that titanium dioxide is fully coated to form a core-shell structure.
[0072] In some embodiments, the hydrolysis reaction and the oxidation reaction include the steps of:
[0073] Prepare an aqueous solution of the iridium precursor;
[0074] Titanium dioxide was added to the aqueous solution to prepare a dispersion;
[0075] An alkaline substance is added to the dispersion to initiate a hydrolysis reaction;
[0076] Hydrogen peroxide is added to the hydrolysis reaction system to carry out an oxidation reaction.
[0077] In some embodiments, the hydrolysis reaction takes less than 1 hour. Further, the hydrolysis reaction takes 0.5 to 1 hour.
[0078] In some embodiments, the oxidation reaction takes 1 to 6 hours. Further, the oxidation reaction takes 2.5 to 3.5 hours.
[0079] In some embodiments, after the oxidation reaction is complete, the following step is also included:
[0080] The oxidation reaction system is filtered, washed, and dehydrated to obtain a precursor of an iridium-based supported catalyst, which is then calcined.
[0081] Dehydration processes include hot air drying, vacuum drying, or heat drying.
[0082] Furthermore, after the oxidation reaction is complete, the following steps are also included:
[0083] The oxidation reaction system is filtered, washed, and dried to obtain a precursor of an iridium-based supported catalyst, which is then calcined.
[0084] Furthermore, the drying temperature is 60℃~100℃; the drying time is 8h~16h.
[0085] A second aspect of this application provides an iridium-based supported catalyst, comprising a core and a shell covering the core; the core comprises TiO2, and the shell comprises IrO2.x , where x = 1 to 2.
[0086] The iridium-based supported catalyst IrO provided in this application embodiment is x @TiO2 is a core-shell structure in which iridium oxide is uniformly coated on the surface of titanium dioxide, and the value of x is 1 to 2, that is, the iridium oxide can be a multivalent iridium oxide. This catalyst can effectively reduce the iridium loading and has high catalytic performance.
[0087] In some implementations, the thickness of the shell is 1 nm to 10 nm.
[0088] In this embodiment, a nanometer-thick shell of iridium oxide is formed on the surface of titanium dioxide, which facilitates the formation of a uniform conductive network and reduces the iridium loading. In specific examples, the shell thickness is 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, and 10 nm, etc.
[0089] In some embodiments, IrO is calculated based on the total mass of the catalyst. x The mass percentage content is 20% to 75%.
[0090] Furthermore, based on the total mass of the catalyst, IrO x The mass percentage content is 20% to 40%.
[0091] In some embodiments, the iridium-based supported catalyst is prepared using the preparation method described above.
[0092] A third aspect of this application provides a proton exchange membrane electrolysis water membrane electrode, comprising an iridium-based supported catalyst obtained by the above preparation method, or comprising the above-described iridium-based supported catalyst.
[0093] The iridium-based catalyst IrO provided in this application embodiment x @TiO2, with an iridium oxide shell fully covering the surface of titanium dioxide and only a few nanometers thick, effectively reduces the iridium loading and increases its conductivity. This core-shell catalyst exhibits excellent oxygen evolution performance and excellent electrolysis performance in PEM water electrolysis.
[0094] The fourth aspect of this application provides the application of an iridium-based supported catalyst in the water electrolysis reaction, wherein the iridium-based supported catalyst is the iridium-based supported catalyst obtained by the above preparation method, or is the iridium-based supported catalyst described above.
[0095] The iridium-based catalyst IrO provided in this application embodiment x @TiO2 exhibits excellent electrolytic performance in PEM water electrolysis.
[0096] Example 1
[0097] This embodiment provides an iridium-based supported catalyst, which is 40% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0098] Step 1: Dissolve 1.39g IrCl3 in 150mL of ultrapure water, then add 1.12g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 9 using KOH, and finally add 5.3g hydrogen peroxide. React continuously for 3 hours.
[0099] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0100] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air. The iridium-based supported catalyst was named 40% IrO. x @TiO2-NP.
[0101] Following the methods described in steps 1-3 above, an iridium-based supported catalyst was prepared by replacing TiO2 nanoparticles with TiO2 nanowires, and named 40%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 40%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0102] Example 2
[0103] This embodiment provides an iridium-based supported catalyst, which is 20% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0104] Step 1: Dissolve 1.5g H2IrCl6 in 150mL of ultrapure water, then add 1.83g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 9 using KOH, and finally add 3.8g hydrogen peroxide. React continuously for 3h.
[0105] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0106] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air to obtain an iridium-based supported catalyst, named 20%IrO. x @TiO2-NP.
[0107] Following the methods described in steps 1-3 above, an iridium-based supported catalyst was prepared by replacing TiO2 nanoparticles with TiO2 nanowires, and named 20%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 20%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0108] Example 3
[0109] This embodiment provides an iridium-based supported catalyst, which is 30% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0110] Step 1: Dissolve 2.5g H2IrCl6 in 150mL of ultrapure water, then add 4.5g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 9 using KOH, and finally add 5.5g hydrogen peroxide. React continuously for 3 hours.
[0111] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0112] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air to obtain an iridium-based supported catalyst, named 30% IrO. x @TiO2-NP.
[0113] Following the methods described in steps 1-3 above, TiO2 nanoparticles were replaced with TiO2 nanowires to prepare an iridium-based supported catalyst, named 30%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 30%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0114] Example 4
[0115] This embodiment provides an iridium-based supported catalyst, which is 60% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0116] Step 1: Dissolve 2.8g Na2IrCl6 in 150mL of ultrapure water, then add 0.72g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 9 using KOH, and finally add 17.35g hydrogen peroxide. React continuously for 3 hours.
[0117] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0118] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air to obtain an iridium-based supported catalyst, named 60%IrO. x @TiO2-NP.
[0119] Following the methods described in steps 1-3 above, TiO2 nanoparticles were replaced with TiO2 nanowires to prepare an iridium-based supported catalyst, named 60%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 60%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0120] Example 5
[0121] This embodiment provides an iridium-based supported catalyst, which is 75% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0122] Step 1: Dissolve 4.2g Na3IrCl6 in 150mL of ultrapure water, then add 0.5g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 9 using KOH, and finally add 8.35g hydrogen peroxide. React continuously for 3 hours.
[0123] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0124] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air to obtain an iridium-based supported catalyst, named 30%IrO. x @TiO2-NP.
[0125] Following the methods described in steps 1-3 above, TiO2 nanoparticles were replaced with TiO2 nanowires to prepare an iridium-based supported catalyst, named 75% IrO. x@TiO2-NW; An iridium-based supported catalyst, named 75%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0126] Example 6
[0127] This embodiment provides an iridium-based supported catalyst, which is 50% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0128] Step 1: Dissolve 1.39g IrCl3 in 150mL of ultrapure water, then add 0.75g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 13 using KOH, and finally add 10.6g hydrogen peroxide. React continuously for 3 hours.
[0129] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0130] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air. The iridium-based supported catalyst was named 50% IrO. x @TiO2-NP.
[0131] Following the methods described in steps 1-3 above, TiO2 nanoparticles were replaced with TiO2 nanowires to prepare an iridium-based supported catalyst, named 50%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 50%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0132] Example 7
[0133] This embodiment provides an iridium-based supported catalyst, which is 20% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0134] Step 1: Dissolve 1.5g H2IrCl6 in 150mL of ultrapure water, then add 1.83g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 11 using KOH, and finally add 10.6g hydrogen peroxide. React continuously for 3 hours.
[0135] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0136] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air to obtain an iridium-based supported catalyst, named 20%IrO. x @TiO2-NP.
[0137] Following the methods described in steps 1-3 above, an iridium-based supported catalyst was prepared by replacing TiO2 nanoparticles with TiO2 nanowires, and named 20%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 20%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0138] Example 8
[0139] This embodiment provides an iridium-based supported catalyst, which is 50% IrO. x @TiO2-550 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0140] Step 1: Dissolve 1.39g IrCl3 in 150mL of ultrapure water, then add 0.75g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 9 using KOH, and finally add 10.6g hydrogen peroxide. React continuously for 3 hours.
[0141] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0142] Step 3: The product obtained in Step 2 was calcined at 550°C for 1 hour in air. The iridium-based supported catalyst was named 50% IrO. x @TiO2-NP-550.
[0143] Following the methods described in steps 1-3 above, TiO2 nanoparticles were replaced with TiO2 nanowires to prepare an iridium-based supported catalyst, named 50%IrO. x @TiO2-NW-550; An iridium-based supported catalyst, named 50%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR-550.
[0144] Example 9
[0145] This embodiment provides an iridium-based supported catalyst, which is 50% IrO. x@TiO2-450 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0146] Step 1: Dissolve 1.39g IrCl3 in 150mL of ultrapure water, then add 0.75g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 9 using KOH, and finally add 10.6g hydrogen peroxide. React continuously for 3 hours.
[0147] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0148] Step 3: The product obtained in Step 2 was calcined at 450°C for 1 hour in air. The iridium-based supported catalyst was named 50% IrO. x @TiO2-NP-550.
[0149] Following the methods described in steps 1-3 above, TiO2 nanoparticles were replaced with TiO2 nanowires to prepare an iridium-based supported catalyst, named 50%IrO. x @TiO2-NW-450; An iridium-based supported catalyst, named 50%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR-450.
[0150] Example 10
[0151] This embodiment provides an iridium-based supported catalyst, which is 20% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0152] Step 1: Dissolve 1.5g H2IrCl6 in 150mL of ultrapure water, then add 1.83g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 11 using KOH, and finally add 94.8g (1:1000) hydrogen peroxide and react continuously for 3h.
[0153] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0154] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air to obtain an iridium-based supported catalyst, named 20%IrO. x @TiO2-NP.
[0155] Following the methods described in steps 1-3 above, an iridium-based supported catalyst was prepared by replacing TiO2 nanoparticles with TiO2 nanowires, and named 20%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 20%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0156] Example 11
[0157] This embodiment provides an iridium-based supported catalyst, which is 20% IrO. x @TiO2 nanoparticles, where x takes the value of 1 to 2, are prepared using the following method:
[0158] Step 1: Dissolve 1.5g H2IrCl6 in 150mL of ultrapure water, then add 1.83g TiO2 nanoparticles and disperse them evenly in ultrasound. Then adjust the pH of the solution to 11 using KOH, and finally add 47.4g (1:500) hydrogen peroxide and react continuously for 3h.
[0159] Step 2: Filter, wash, and dry the solution obtained in Step 1 to obtain IrO. x @TiO2 material precursor;
[0160] Step 3: The product obtained in Step 2 was calcined at 350°C for 1 hour in air to obtain an iridium-based supported catalyst, named 20%IrO. x @TiO2-NP.
[0161] Following the methods described in steps 1-3 above, an iridium-based supported catalyst was prepared by replacing TiO2 nanoparticles with TiO2 nanowires, and named 20%IrO. x @TiO2-NW; An iridium-based supported catalyst, named 20%IrO, was prepared by replacing TiO2 nanoparticles with TiO2 nanorods. x @TiO2-NR.
[0162] I. Characterization Analysis
[0163] 1. Morphological characterization: 40% IrO obtained in Example 1 x @TiO2-NP and Example 1 yielded 40% IrO x @TiO2-NR, 20% IrO obtained in Example 2 x @TiO2-NW's TEM-mapping, such as Figures 1-3 As shown, it clearly demonstrates the core-shell structure, with its elements evenly distributed on the surface.
[0164] 2. Iridium content detection: The iridium content is mainly determined by TEM mapping, and the results are as follows: Figures 4-6 As shown, the 40% IrO obtained in Example 1 x @TiO2-NP, 40% IrO obtained in Example 1 x @TiO2-NR and the 20% IrO obtained in Example 2 x The iridium contents of @TiO2-NW are 42.48%, 45.51%, and 17.8%, respectively.
[0165] II. Performance Testing
[0166] (I) OER Catalytic Performance Testing:
[0167] 1. Ink configuration:
[0168] Weigh 4 mg of the above sample (40% IrO obtained in Example 1). x @TiO2-NP, 40% IrO obtained in Example 1 x @TiO2-NR and the 20% IrO obtained in Example 2 x Place the TiO2-NW in a glass container, measure 500 μl of water and isopropanol, add 15 μl of nafion, sonicate for half an hour, then measure 6 μl and drop it onto a rotating disk electrode, and let it air dry.
[0169] 2. Electrochemical performance testing:
[0170] The prepared rotating disk electrode was used as the working electrode, the silver / silver chloride electrode as the reference electrode, and the platinum sheet as the counter electrode. It was activated for 50 cycles at 0-1.5V and finally tested at 1.1-1.7V RHE at a scan rate of 5mV / s.
[0171] Test results are as follows Figure 7 As shown: 40% IrO x @TiO2-NP at a current density of 10 mA / cm² 2 At that time, its overpotential was 315mV; 40% IrO x @TiO2-NR at a current density of 10 mA / cm² 2 At that time, its overpotential was 325mV; 20% IrO x @TiO2-NW at a current density of 10 mA / cm² 2 At that time, its overpotential was 328mV.
[0172] (II) Electrolysis water performance test:
[0173] 1. Membrane electrode fabrication:
[0174] Cathode ink preparation: Weigh 0.5 g of 50% Pt / C, 4 g of water, and 36 g of isopropanol into a beaker. Stir at 17000 rpm for 1 h using an emulsifying shear press. Then, ultrasonically spray the mixture onto a 125 μm membrane from Dongyue, with a loading of 0.1 mg / cm³. 2 .
[0175] Anode ink preparation: Weigh 0.5g of the above catalyst (40% IrO obtained in Example 1). x @TiO2-NP, 40% IrO obtained in Example 1 x @TiO2-NR and the 20% IrO obtained in Example 2 x In a beaker, 3.2 g of TiO2-NW, 3.2 g of water, and 36.8 g of isopropanol were mixed and stirred at 14000 rpm for 30 min using an emulsifying shear press. The resulting mixture was then ultrasonically sprayed onto the reverse side of the cathode with an anode catalyst loading of 0.1 mg / cm³. 2 .
[0176] 2. Assembly of the electrolytic cell:
[0177] The device uses titanium felt as the anode diffusion layer, carbon paper as the cathode diffusion layer, PTFE as the sealant, and self-made electrode plates and end plates to assemble the electric water device.
[0178] 3. Electrolysis water performance test:
[0179] PEM electrolysis cell testing, such as Figure 8 As shown. Specifically, ultrapure water was used, the test temperature was 60–80℃, the proton exchange membrane thickness was 125 μm, the water flow rate was 600 ml / min, and the test procedure was as follows: when the current density was less than 0.05 A / cm²... 2 At that time, from 0.01A / cm 2 Initially, increment by 0.01; when the current density is less than 0.1 A / cm² 2 Greater than 0.05A / cm 2 When the current density increases by 0.025, the current density increases by 0.4 A / cm². 2 Greater than 0.1A / cm 2 When the current density increases by 0.05, the current density increases by 0.05; when the current density is less than 1 A / cm 2 Greater than 0.4A / cm 2 When the current density increases by 0.1, the current density increases by 0.1; when the current density is less than 3 A / cm², the current density increases by 0.1. 2 Greater than 1A / cm 2 The current density increases by 0.2 at a time; each current density is maintained for 50 seconds.
[0180] Test results: such as Figure 9 As shown, with 40% IrO xThe electrolytic cell with @TiO2-NP as the catalyst operates at a current density of 1 A / cm². 2 2A / cm 2 At that time, its electrolysis voltage was 1.66V and 1.79V; with 40% IrO x @TiO2-NR is the catalyst in the electrolytic cell, with a current density of 1 A / cm². 2 2A / cm 2 At that time, its electrolysis voltage was 1.67V and 1.8V; with 20% IrO x The electrolytic cell with TiO2-NW as the catalyst was used at a current density of 1 A / cm². 2 2A / cm 2 At that time, its electrolysis voltage was 1.64V and 1.77V.
[0181] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for preparing an iridium-based supported catalyst, characterized in that, include: Using titanium dioxide as a carrier, an iridium precursor was hydrolyzed with an alkaline substance, and the hydrolysis product was then oxidized with hydrogen peroxide to obtain a precursor for an iridium-based supported catalyst. The iridium-based supported catalyst precursor was calcined in an oxygen atmosphere to prepare the iridium-based supported catalyst IrO. x @TiO2, where x = 1~2, IrO x It acts as a shell covering the surface of the TiO2 core.
2. The method for preparing the iridium-based supported catalyst according to claim 1, characterized in that, The raw materials must meet at least one of the following conditions (1) to (3): (1) The iridium precursor includes at least one of IrCl3, Na3IrCl6, Na2IrCl6 and H2IrCl6; (2) The alkaline substance includes at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate and lithium carbonate; (3) The morphology of the titanium dioxide includes at least one of titanium dioxide nanoparticles, titanium dioxide nanowires and titanium dioxide nanorods.
3. The method for preparing the iridium-based supported catalyst according to claim 1 or 2, characterized in that, In the hydrolysis reaction steps, the pH value is controlled to be 9~13.
4. The method for preparing the iridium-based supported catalyst according to claim 1 or 2, characterized in that, In the calcination process, the control parameters satisfy: The calcination temperature is 250 ℃~450 ℃; and / or the calcination time is 0.5 h~2 h.
5. The method for preparing the iridium-based supported catalyst according to claim 1 or 2, characterized in that, The molar mass ratio of iridium atoms to hydrogen peroxide in the iridium precursor is 1:20 to 1:1000; and / or, the molar mass ratio of iridium atoms to titanium dioxide in the iridium precursor is 1:1 to 1:
10.
6. The method for preparing the iridium-based supported catalyst according to claim 1 or 2, characterized in that, The hydrolysis reaction and the oxidation reaction include the following steps: Prepare an aqueous solution of the iridium precursor; The titanium dioxide is added to the aqueous solution to prepare a dispersion; An alkaline substance is added to the dispersion to initiate a hydrolysis reaction; Hydrogen peroxide is added to the hydrolysis reaction system to carry out an oxidation reaction.
7. An iridium-based supported catalyst, characterized in that, It includes a core and a shell covering the core; the core comprises TiO2, and the shell comprises IrO. x Where x = 1~2; IrO x The mass percentage content is 20%~75%; the iridium-based supported catalyst is prepared by the preparation method according to any one of claims 1 to 6.
8. A proton exchange membrane electrolysis water membrane electrode, characterized in that, The catalyst includes the iridium-based supported catalyst obtained by the preparation method according to any one of claims 1 to 6, or the iridium-based supported catalyst according to claim 7.
9. The application of an iridium-based supported catalyst in the electrolysis of water reaction, wherein the iridium-based supported catalyst is the iridium-based supported catalyst obtained by the preparation method according to any one of claims 1 to 6, or is the iridium-based supported catalyst according to claim 7.