Sol-gel preparation method and application of iridium-based electro-catalytic material
The iridium-based catalyst is prepared by the sol-gel method, which solves the problems of complex operation and scarce resources in the preparation of IrO2 catalysts, achieves efficient and stable electrocatalytic water oxidation performance, and is suitable for high-performance water electrolysis systems.
Patent Information
- Application Number
- CN202510876192.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-10-17
AI Technical Summary
Existing IrO2 catalyst preparation methods have problems such as high operating temperature, high pressure, uneven component mixing, and easy agglomeration of product particles, which limit the improvement of catalytic performance. In addition, Ir element resources are scarce and expensive.
The sol-gel method is adopted, using iridium acetate and non-precious metal salts as precursors, combined with acrylic acid and polyethylene glycol diacrylate, and gelation is initiated by low-temperature heat treatment to construct a three-dimensional network structure. The use of initiators such as Na2S2O8 is avoided, the preparation process is simplified, and a low-iridium-loaded nanocatalyst with high dispersion, high activity and structural stability is prepared.
It significantly improves the structural uniformity and specific surface area of the catalyst, enhances the electrochemical activity and stability, reduces the risk of loss of iridium-based catalysts, and is suitable for high-performance water electrolysis systems such as proton exchange membrane electrolyzers.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of water electrolysis catalyst materials, and relates to a sol-gel preparation method of an iridium-based electrocatalytic material and application thereof. BACKGROUND
[0002] The water oxidation reaction (OER) as an anode reaction in the process of hydrogen production by water electrolysis has slow reaction kinetics, which becomes a key bottleneck limiting the overall energy efficiency improvement. Developing OER catalyst materials with high activity and stability is one of the important directions of current electrocatalysis and new energy technology research.
[0003] At present, platinum group metal oxides, especially iridium oxide (IrO2) and ruthenium oxide (RuO2), are considered to be the most potential OER catalysts due to their excellent electrocatalytic activity and chemical stability in acidic electrolyte. Among them, IrO2 has higher stability and can still maintain good catalytic performance in the strong corrosive proton exchange membrane water electrolysis environment, and is therefore widely used as an anode catalyst material. However, the resource of Ir element is scarce and expensive, and how to improve its atomic utilization and optimize its structure to enhance the catalytic performance and durability is the core problem in this research field. For this reason, researchers have proposed various preparation strategies for IrO2, such as pyrolysis method, coprecipitation method, hydrothermal method, etc., to control the particle size, crystal structure and dispersibility. However, these traditional methods often have problems such as high operating temperature or pressure, uneven mixing of components, and easy agglomeration of product particles, resulting in low specific surface area of the catalyst and insufficient utilization of active sites, which limits the further improvement of the catalytic performance.
[0004] As a "bottom-up" material preparation strategy, the sol-gel method has attracted widespread attention in the field of catalytic material synthesis in recent years due to its advantages such as uniform mixing of precursor solution, mild reaction conditions, and easy control of microstructure. This method forms a uniform metal organic complex sol, which is then converted into a gel precursor under suitable conditions, and then nanoscale metal oxide materials are formed through drying and calcination. Compared with traditional synthesis methods, the sol-gel method can achieve fine dispersion of catalytic components at the molecular level, thereby significantly improving the structural uniformity and specific surface area of the catalyst, and enhancing its electrochemical activity and stability. However, compared with other preparation methods, the sol-gel method, especially the gelation method induced by heat treatment, has not been reported in the preparation of iridium-based water oxidation electrocatalyst materials. SUMMARY
[0005] The purpose of the present application is to overcome the defects of the prior art and provide a sol-gel preparation method of an iridium-based water oxidation catalyst material and its application in water electrolysis.
[0006] The present application is based on a sol-gel method, using iridium acetate and non-noble metal salt as precursors, while introducing acrylic acid and polyethylene glycol diacrylate, initiating gelation through low-temperature heat treatment, and constructing a three-dimensional network structure. This method does not require practical Na2S2O8 initiator, avoids the post-processing step of washing sodium salt after heat treatment, significantly simplifies the preparation process and avoids the disadvantages of loss of expensive iridium-based catalyst caused by the washing step, while also maximizing the maintenance of the original structural characteristics of the material, fully exposing its catalytic active sites. Finally, a low-iridium-loading nanocatalyst with high dispersity, high activity and structural stability is successfully prepared. The catalyst is suitable for proton exchange membrane (PEM) electrolytic cells and other high-performance water electrolysis systems, and has broad industrial application prospects.
[0007] The object of the present application can be achieved by the following technical solutions:
[0008] One of the objects of the present application is to propose a method for preparing an iridium-based catalyst material based on a sol-gel method, comprising the following steps:
[0009] (1) A certain amount of iridium acetate and non-noble metal salt is dissolved in a mixed solution composed of a certain amount of deionized water, acrylic acid and polyethylene glycol diacrylate, and magnetic stirring is adopted to form a uniform transparent sol system;
[0010] (2) The sol is dried under constant temperature conditions in an oven, and after it is converted into a gel, it is taken out, the obtained gel is crushed and dried again to obtain a precursor powder;
[0011] (3) The precursor powder is heated to a certain temperature at a certain heating rate in an air atmosphere, and after heat preservation for a period of time, it is naturally cooled to room temperature to obtain a highly dispersed low-loading iridium-based catalyst powder.
[0012] Further, in step one, the molar ratio of iridium acetate and metal salt is 1:3.
[0013] Further, in step one, the metal salt is one of manganese acetylacetone, chromium oxalate and ammonium metatungstate.
[0014] Further, in step one, the mass ratio of polyethylene glycol diacrylate and acrylic acid is 1:100.
[0015] Further, in step one, the magnetic stirring time is 30 min.
[0016] Further, in step two, the constant temperature drying temperature is 80℃, and the drying time is 6h.
[0017] Further, in step three, the calcination temperature is 450℃, and the calcination time is 2h.
[0018] Further, in step three, the heating rate of the calcination process is 5℃ / min
[0019] Further, in step three, the calcination atmosphere is preferably air, oxygen or other oxygen-containing gas, and more preferably oxygen.
[0020] The acrylic acid is used as a network skeleton monomer, and the polyethylene glycol diacrylate is used as a crosslinking agent, so that a three-dimensional dispersion network can be formed under low-temperature heat treatment conditions, and the pore structure and uniformity of the finished catalyst product are improved. The sol-gel method does not need to use Na2S2O8 and other initiators, avoids the post-processing step of washing sodium salt after heat treatment, significantly simplifies the preparation process and avoids the disadvantages of loss of expensive iridium-based catalysts caused by the water washing step, and at the same time, the original structure characteristics of the material can be maintained to the maximum extent, and the catalytic active sites are fully exposed.
[0021] The second purpose of the present application is to provide a low-iridium-loading nanoparticle material prepared by the above method.
[0022] The third purpose of the present application is to provide an application of the above iridium-based nanoparticle material as a water oxidation catalyst in the electrolytic hydrogen production, which can effectively reduce the loading of iridium-based noble metal catalyst materials while ensuring the electrocatalytic water oxidation performance.
[0023] Compared with the prior art, the present application has the following obvious advantages:
[0024] (1) The present application uses a sol-gel method to synthesize a low-iridium-loading nanoparticle catalyst material by low-temperature heat treatment to initiate gelation (without using Na2S2O8 and other initiators), which can realize uniform dispersion of iridium and doped elements in a solution system, thereby effectively controlling the particle size and morphology of the product, obtaining an iridium oxide material with large specific surface area and uniform structure, and significantly improving the electrocatalytic activity and stability thereof;
[0025] (2) The preparation method has mild preparation conditions, does not need high pressure or complex equipment, has strong controllability, and has no subsequent purification separation and washing salt removal process, so that the loss of expensive iridium-based catalysts can be avoided, and the method is suitable for large-scale production, and the obtained catalyst exhibits electrocatalytic water oxidation performance in an acidic medium;
[0026] (3) Combined with a membrane electrode assembly, the present application can realize high compatibility with a PEM water electrolysis system, meet the requirements of industrial-level continuous operation, and has a broad practical application prospect. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 The XRD pattern of the prepared MnIrO x The XRD pattern of the prepared MnIrO
[0028] Figure 2 The XRD pattern of the prepared MnIrO xSEM image of the nanomaterial;
[0029] Figure 3 MnIrO x TEM image of the nanomaterial;
[0030] Figure 4 MnIrO x XRD image of the nanomaterial;
[0031] Figure 5 MnIrO x SEM image of the nanomaterial;
[0032] Figure 6 MnIrO x TEM image of the nanomaterial;
[0033] Figure 7 CrIrO x SEM image of the nanomaterial;
[0034] Figure 8 MnIrO x , MnIrO x , MnIrO x Cyclic voltammogram of the nanomaterial;
[0035] Figure 9 MnIrO x PEM electrolysis water stability curve of the nanomaterial. DETAILED DESCRIPTION
[0036] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.
[0037] Example 1:
[0038] Preparation of iridium-based water oxidation catalyst materials by sol-gel method
[0039] (1) Preparation of catalyst precursor sol
[0040] At room temperature, 60 mg of iridium acetate and 178 mg of manganese acetylacetonate were sequentially added to a mixed solution containing 20 g of deionized water, 3 g of acrylic acid and 0.03 g of polyethylene glycol diacrylate, and magnetic stirring was performed for 30 min to promote uniform dispersion of the metal components and complexation reaction. The obtained solution was clear and transparent, forming a stable sol system.
[0041] (2) Preparation of MnIrO x Catalyst materials
[0042] The sol was dried in an 80 °C constant temperature oven for 6 h, and after it was converted into a gel, it was taken out, gently ground into fine gel pieces, and dried again at 80 °C to obtain a light gray xerogel precursor powder. The xerogel precursor was loaded into a porcelain boat and heated in a muffle furnace to 450 °C at a heating rate of 5 °C / min under an air atmosphere, and calcined for 30 min. After cooling, a uniform black powder was obtained.
[0043] Figure 1 The XRD pattern of the prepared MnIrO x nanomaterials is shown in Figure 1. From the diffraction peak positions in the figure, it can be seen that the prepared material is a coexisting IrO2 and MnO2 nanomaterial. Figure 2 and Figure 3 The XRD pattern of the prepared MnIrO x nanomaterials is shown in Figure 1. From the diffraction peak positions in the figure, it can be seen that the prepared material is a coexisting IrO2 and MnO2 nanomaterial.
[0044] The XRD, SEM, and TEM results show that the highly dispersed MnIrO x nanoparticle material was successfully prepared. Since the gelation was initiated by low-temperature heat treatment, no initiator such as Na2S2O8 was used, avoiding the post-processing step of washing with water to remove sodium salt after heat treatment, significantly simplifying the preparation process and avoiding the loss of expensive iridium-based catalysts caused by the water washing step, while also maximizing the maintenance of the original structural characteristics of the material, fully exposing its catalytic active sites, providing abundant catalytic active sites for the electrocatalytic water oxidation process, and thus enhancing its electrocatalytic water oxidation performance.
[0045] Example 2:
[0046] Preparation of an iridium-based water oxidation catalyst material by a sol-gel method
[0047] (1) Preparation of the catalyst precursor sol
[0048] At room temperature, 60 mg of iridium acetate and 123 mg of ammonium metatungstate were sequentially added to a mixed solution containing 20 g of deionized water, 3 g of acrylic acid, and 0.03 g of polyethylene glycol diacrylate, and magnetic stirring was performed for 30 min to promote the uniform dispersion and complexation of the metal components. The obtained solution was clear and transparent, forming a stable sol system.
[0049] (2) Preparation of a Wi rO x based catalyst material by high-temperature calcination
[0050] The sol was dried in a constant temperature oven at 80°C for 6h, and after it was changed into a gel, it was taken out and ground into fine gel pieces, and then dried again at 80°C to obtain a light gray xerogel precursor powder. The xerogel precursor was loaded into a porcelain boat and heated in a muffle furnace to 450°C at a heating rate of 5°C / min in an air atmosphere, and then calcined at a constant temperature for 30 min. After cooling, a uniform black powder particle material was obtained.
[0051] Figure 4 The prepared WIrO x The XRD pattern of the nanomaterials was obtained by comparing the diffraction peak positions in the figure with the standard PDF card, and the prepared nanomaterials were IrO2 and WO3 coexisting nanomaterials. Figure 5 and Figure 6 The SEM and TEM images of the prepared Ir-W nanomaterials can be seen from the figure, and the nanomaterials have a uniform nanoparticle structure, and the particle size is 10-30 nm.
[0052] The above XRD, SEM and TEM results prove that the highly dispersed WIrO x co-doped nanoparticle material is successfully prepared. Since the gelation is initiated by a low-temperature heat treatment method, no initiator such as Na2S2O8 is used, the post-processing step of washing with water to remove sodium salt after heat treatment is avoided, the preparation process is significantly simplified, and the disadvantages of loss of expensive iridium-based catalyst caused by the water washing step are avoided, while the original structure characteristics of the material are also maintained to the maximum extent, the catalytic active sites are fully exposed, and the electrocatalytic water oxidation process is provided with abundant catalytic active sites, thereby enhancing the electrocatalytic water oxidation performance.
[0053] Example 3:
[0054] Preparation of iridium-based water oxidation catalyst material by sol-gel method
[0055] (1) Preparation of catalyst precursor sol
[0056] At room temperature, 60 mg of iridium acetate and 96 mg of chromium oxalate were sequentially added to a mixed solution containing 20 g of deionized water, 3 g of acrylic acid, and 0.03 g of polyethylene glycol diacrylate, and magnetic stirring was performed for 30 min to promote the uniform dispersion and complexation reaction of the metal components. The obtained solution is clear and transparent, forming a stable sol system.
[0057] (2) Preparation of CrIrO x based catalyst material by high-temperature calcination
[0058] The sol was dried in an 80 °C constant temperature oven for 6 h, and after it was converted into a gel, it was taken out, gently ground into fine gel pieces, and dried again at 80 °C to obtain a light gray xerogel precursor powder. The xerogel precursor was loaded into a porcelain boat and heated to 450 °C at a heating rate of 5 °C / min in a muffle furnace under an air atmosphere, and calcined for 30 min. After cooling, a uniform black powder-like particulate material was obtained.
[0059] Figure 7 To prepare the CrIrO x The SEM image of the nanomaterial shows that the nanomaterial has a uniform nanoparticle structure, and the particle size is 20-40 nm. Since the gelation is induced by low-temperature heat treatment, no initiator such as Na2S2O8 is used, and the post-processing step of washing with water to remove sodium salt after heat treatment is avoided, which significantly simplifies the preparation process and avoids the disadvantages of loss of expensive iridium-based catalysts caused by the water washing step, while also maximizing the maintenance of the original structural characteristics of the material, fully exposing the catalytic active sites, providing abundant catalytic active sites for the electrocatalytic water oxidation process, and further enhancing the electrocatalytic water oxidation performance.
[0060] Example 4:
[0061] The iridium-based powder materials prepared in Examples 1, 2 and 3 were used as water oxidation electrocatalysts to construct working electrodes, and the electrochemical performance of water oxidation was tested under acidic conditions, with the specific steps as follows:
[0062] Preparation of working electrode: 4 mg of the prepared iridium-based catalyst powder was added to 800 μL of deionized water and 200 μL of isopropyl alcohol (V 水 :V 异丙醇 = 4:1) mixed solvent, followed by the addition of 24 μL of 5 wt.% Nafion solution. The above solution was ultrasonically dispersed for 30 min to form a uniform catalyst slurry. Then, 5 μL of the slurry was dropped onto the surface of a glassy carbon electrode with a diameter of 3 mm, and the working electrode for testing was obtained after natural drying.
[0063] Electrochemical test: The electrocatalytic performance test was carried out in a three-electrode system electrolytic cell, and the working electrode was the glassy carbon electrode loaded with the iridium-based catalyst material as described above, the counter electrode was a platinum sheet, and the reference electrode was a saturated calomel electrode (SCE). The electrolyte was a 0.5 M H2SO4 solution saturated with N2, and the test temperature was controlled at 25±2 °C. The electrocatalytic water oxidation performance of the material was tested by cyclic voltammetry (CV) with a scan rate of 100 mV·s -1 .
[0064] As shown in Figure 8 , compared with the Wi rO x and CrIrO xThe material, MnIrO x The material exhibits excellent electrocatalytic water oxidation catalytic performance under acidic conditions, and can achieve a current density of 90 mA·cm -2 at 1.645 V vs. RHE.
[0065] Example 5:
[0066] The MnIrO x material prepared in Example 1 was used as an anode water oxidation catalyst, commercial 20wt% Pt / C was used as a cathode water reduction catalyst, and Nafion 115 was used as a proton exchange membrane interlayer. A membrane electrode was prepared by a conventional ultrasonic spray coating method, and the specific steps are as follows:
[0067] First, 5ul of 20% Nafion solution was taken with a precision pipette and added to 1 milliliter of mixed solvent prepared by mixing deionized water and isopropanol at a ratio of 1:1. Then, the pre-synthesized MnIrO x catalyst sample was accurately weighed by a precision electronic balance and added to the above mixed solution for ultrasonic homogenization. The prepared catalyst slurry was uniformly coated on one working surface of the Nafion proton exchange membrane using ultrasonic atomization spray technology, and the loading amount of iridium catalyst was controlled at 0.8 mg Ir / cm 2 . For the other working surface of the membrane electrode, Pt / C catalyst was sprayed according to the same preparation process, and the loading amount of platinum was controlled at 0.2 mg Pt / cm 2 .
[0068] The prepared membrane electrode was tested for overall water splitting. As Figure 9 shown, under the conditions of a temperature of 60℃ and a current density of 1 A·cm -2 , electrolysis was carried out for 500 hours, and the driving voltage required by the electrolytic cell was 1.75 V, and no activity decay was observed, indicating that the catalyst has excellent catalytic activity and stability in the process of electrocatalytic water oxidation reaction.
[0069] The above description of the embodiments is to facilitate the understanding and use of the invention by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art without departing from the scope of the present application should be within the scope of protection of the present application.
Claims
1. A sol-gel method for preparing an iridium-based electrocatalytic material, characterized in that: The following steps are involved: Step 1: dissolving iridium acetate and a non-precious metal salt in a mixed solution consisting of deionized water, acrylic acid, and a cross-linking agent, and stirring magnetically to form a uniform and transparent sol system; Step 2: drying the sol at a constant temperature, taking out and crushing the sol after forming a colloid, and drying it again at a constant temperature to obtain a gel precursor powder; Step 3: pyrolyze the precursor powder to obtain a low iridium loading powder catalyst material.
2. The preparation method according to claim 1, wherein: In the step 1, the molar ratio of iridium acetate to the non-noble metal salt is 1:
3.
3. The preparation method according to claim 1, wherein: In the step 1, the non-noble metal salt is one of manganese acetylacetonate, chromium oxalate, and ammonium metatungstate.
4. The preparation method according to claim 1, wherein: In the step 1, the mass ratio of polyethylene glycol diacrylate to acrylic acid is 1:
100.
5. The preparation method according to claim 1, wherein: In the step 1, the cross-linking agent is polyethylene glycol diacrylate.
6. The preparation method according to claim 1, wherein: In the step 2, the drying atmosphere is air, the drying temperature is 80° C., and the drying time is 6 h.
7. The preparation method according to claim 1, characterized in that Its characteristics are: In the step 3, the pyrolysis treatment is carried out by calcination, the calcination temperature is 450° C., and the calcination time is 2 hours.
8. The preparation method according to claim 1, wherein: In the step 3, the calcination atmosphere is preferably an oxygen-containing gas such as air or oxygen, and more preferably oxygen.
9. The low iridium loading nanomaterial prepared by the gel-sol method according to any one of claims 1 to 8 is used as a water oxidation catalyst in acidic proton exchange membrane water electrolysis to produce hydrogen.