Honeycomb type composite ruthenium oxide / iridium oxide catalyst
By preparing honeycomb composite ruthenium oxide/iridium oxide catalyst, the stability and cost of existing catalysts are solved by using the mesoporous silicon oxide template agent and the oxygen vacancy stability of ruthenium oxide, and the cost of existing catalysts is achieved, and efficient hydrogen production performance of electrolytic water is achieved.
Patent Information
- Application Number
- CN202510553935.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-29
- Publication Date
- 2025-08-15
AI Technical Summary
In the existing PEM electrolytic hydrogen production technology, the stability and cost of the catalyst are problematic, especially the ruthenium-based catalyst is unstable under acidic conditions, and the iridium catalyst is expensive.
The preparation method of honeycomb composite ruthenium oxide/iridium oxide catalyst is adopted to form a honeycomb structure by mesoporous silicon oxide as a template agent, and ruthenium oxide is used to encapsulate iridium oxide, and the oxygen vacancy stability of ruthenium oxide is used to avoid performance reduction caused by heat treatment under oxygen conditions. The molar ratio of iridium to ruthenium is (0.4-0.6): (0.6-0.4).
High catalytic activity with low iridium load is achieved, the oxygen evolution overpotential is not higher than 282mV, and the electrolytic voltage shows excellent electrolytic performance at different current densities, and the stability is significantly improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of PEM water electrolysis hydrogen production catalysts, and in particular relates to a honeycomb-type composite ruthenium oxide / iridium oxide catalyst. Background Art
[0002] PEM water electrolysis hydrogen production technology uses proton exchange membrane (PEM) as the electrolyte, which can effectively block gases and achieve efficient separation of hydrogen and oxygen during water electrolysis. It has a high operating current density and can operate at relatively low temperatures and pressures, facilitating system integration and large-scale application. It is of great significance to promote the large-scale storage and conversion of renewable energy and build a clean and low-carbon energy system, and has broad development prospects and application space.
[0003] Catalysts play a crucial role in PEM water electrolysis hydrogen production technology, directly affecting electrolysis efficiency, cost, and overall performance. Catalysts can significantly reduce the overpotential of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), thereby improving the efficiency of water electrolysis. For example, oxides of iridium (Ir) and ruthenium (Ru) (such as IrO2 and RuO2) are commonly used anode catalysts that can effectively promote OER.
[0004] However, the catalysts used in water electrolysis are either unstable or too expensive. For example, iridium is expensive, and pure iridium catalysts are also expensive; ruthenium-based catalysts are unstable under acidic conditions and easily degrade.
[0005] Therefore, in PEM water electrolysis hydrogen production technology, catalysts with high activity, low cost and good stability are currently being developed. Summary of the Invention
[0006] Purpose of the invention: The present invention provides a honeycomb-type composite ruthenium oxide / iridium oxide catalyst with high activity and strong stability.
[0007] Technical solution: The honeycomb-type composite ruthenium oxide / iridium oxide catalyst of the present invention is prepared by the following steps:
[0008] (1) mixing mesoporous silica, a ruthenium source, a co-oxidant, and a solvent, and evaporating to dryness to obtain a ruthenium precursor mixture;
[0009] (2) heat-treating the ruthenium precursor mixture in an air atmosphere at 400-500° C. for 2-3 hours to obtain a supported ruthenium oxide catalyst;
[0010] (3) mixing a supported ruthenium oxide catalyst, an iridium source, a co-oxidant, and a solvent, and evaporating the mixture to obtain an iridium precursor mixture;
[0011] (4) heat-treating the iridium precursor mixture in an air atmosphere at 400-500° C. for 2-3 h to obtain a supported ruthenium-iridium catalyst;
[0012] (5) After the supported ruthenium-iridium catalyst is alkaline-washed to remove the mesoporous silica, it is washed, filtered and dried to obtain a honeycomb-type iridium oxide-coated ruthenium oxide composite catalyst.
[0013] The composite catalyst of the present invention uses mesoporous silica as a template to form a honeycomb structure of ruthenium oxide and an iridium oxide composite catalyst that wraps the ruthenium oxide. The ruthenium oxide is used to improve the mechanical properties of the overall catalyst and enhance the stability. At the same time, by adjusting the preparation process, the reduction in the catalytic performance of the ruthenium oxide caused by repeated heating under oxygen conditions during the preparation of the composite catalyst can be effectively avoided.
[0014] That is, during the preparation process, ruthenium oxide is first heat-treated under oxygen conditions to form ruthenium oxide. The ruthenium oxide obtained under these conditions has a certain amount of oxygen vacancies. Based on silicon dioxide as a template, the hydroxyl groups of the silicon dioxide can interact with the loaded oxygen atoms or oxygen vacancies at the interface, thereby stabilizing the oxygen vacancies in the ruthenium oxide and improving the catalytic performance of the catalyst. Under these conditions, when the composite of silicon dioxide and ruthenium oxide is heat-treated again with an iridium source in an oxygen atmosphere to react to form iridium oxide, the protection of the oxygen vacancies in the ruthenium oxide by silicon dioxide can effectively prevent the oxygen vacancies in the ruthenium oxide from being filled during the heat treatment in the oxygen atmosphere, thereby stabilizing the catalytic performance of the entire composite catalyst prepared and avoiding the catalytic performance degradation of the entire composite catalyst caused by the introduction of ruthenium oxide during the preparation process.
[0015] Furthermore, the molar ratio of iridium to ruthenium in the composite catalyst is (0.4-0.6):(0.6-04).
[0016] Furthermore, in the preparation step (1) of the composite catalyst, the pore size of the mesoporous silica is 5-7 nm.
[0017] Furthermore, in the preparation step (1) of the composite catalyst, the ruthenium source is ruthenium chloride, ruthenium nitrate or ruthenium acetate, and the molar ratio of mesoporous silica to ruthenium in the ruthenium source is (2-4):1.
[0018] Furthermore, in the preparation step (1) of the composite catalyst, the co-oxidant includes sodium nitrate or potassium nitrate, and the molar ratio of the co-oxidant to the ruthenium in the ruthenium source is (50-100):1.
[0019] Furthermore, in step (3) of preparing the composite catalyst, the iridium source is iridium trichloride or chloroiridic acid.
[0020] Furthermore, in step (3) of preparing the composite catalyst, the co-oxidant includes sodium nitrate or potassium nitrate, and the molar ratio of the co-oxidant to the iridium in the iridium source is (50-100):1.
[0021] Furthermore, in step (5) of preparing the composite catalyst, the alkaline solution is a sodium hydroxide solution, and the alkaline washing is performed until no silicon content is detected.
[0022] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: the honeycomb composite ruthenium oxide / iridium oxide catalyst not only has a low iridium loading, but also has an oxygen evolution overpotential of no more than 282mV after testing; at 80°C and 1A / cm 2 Under these conditions, the electrolysis voltage of a single cell is 1.593V-1.617V; 2A / cm 2 Under these conditions, the electrolysis voltage of a single cell is 1.732V-1.756V; 3A / cm 2 Under these conditions, the electrolysis voltage of a single cell is 1.861V-1.885V, indicating high catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 The electrolysis voltage data of the single cell of the catalyst prepared in Examples 1-5 and Comparative Examples 1-3 are shown;
[0024] Figure 2 Graph showing the single cell stability data of the catalysts prepared in Example 1 and Comparative Example 3. DETAILED DESCRIPTION
[0025] The technical solution of the present invention is further described in detail below with reference to the embodiments.
[0026] The pore size of the mesoporous silica used in the following examples of the present invention is 5-7 nm.
[0027] The raw materials used in the present invention are all purchased from the market, and the composition information is shown in Table 1 below.
[0028] Table 1 Raw material information
[0029]
[0030]
[0031] Example 1
[0032] In the preparation of the honeycomb composite ruthenium oxide / iridium oxide catalyst of Example 1, the molar ratio of iridium to ruthenium is 1.5:1; the molar ratio of mesoporous silica to ruthenium in ruthenium trichloride is 3:1; the molar ratio of the pro-oxidant sodium nitrate to ruthenium in ruthenium trichloride is 75:1; and the molar ratio of the pro-oxidant sodium nitrate to iridium in iridium trichloride is 75:1. Specifically, the steps include:
[0033] (1) 0.2 g of ruthenium trichloride, 0.132 g of mesoporous silica support, and 4.67 g of sodium nitrate were mixed in 40 g of ultrapure water, the mixed solution was sonicated for 10 min, and stirred and evaporated to dryness at 80° C. to obtain a ruthenium precursor mixture;
[0034] (2) treating the ruthenium precursor mixture in an air atmosphere at 400° C. for 3 h to obtain a supported ruthenium oxide catalyst;
[0035] (3) Mixing a supported ruthenium oxide catalyst, 0.39 g of iridium trichloride, and 7 g of sodium nitrate in 40 g of ultrapure water, stirring and evaporating at 80° C. to obtain an iridium precursor mixture;
[0036] (4) treating the iridium precursor mixture in an air atmosphere at 400° C. for 2 h to obtain a supported ruthenium-iridium catalyst;
[0037] (5) The supported ruthenium-iridium catalyst was washed in a 1M sodium hydroxide solution for 6 hours, i.e., the silicon-free content was detected; and then filtered and dried to obtain a honeycomb mesoporous iridium oxide-coated ruthenium oxide composite catalyst.
[0038] Example 2
[0039] In the preparation of the honeycomb composite ruthenium oxide / iridium oxide catalyst of Example 2, the molar ratio of iridium to ruthenium is 1.5:1; the molar ratio of mesoporous silica to ruthenium in ruthenium nitrate is 2:1; the molar ratio of the pro-oxidant sodium nitrate to ruthenium in ruthenium nitrate is 50:1; and the molar ratio of the pro-oxidant sodium nitrate to iridium in chloroiridic acid is 100:1. The process specifically includes the following steps:
[0040] (1) 0.2 g of ruthenium nitrate, 0.09 g of mesoporous silica support, and 3.7 g of potassium nitrate were mixed in 40 g of ultrapure water, the mixed solution was sonicated for 10 min, and stirred and evaporated to dryness at 80° C. to obtain a ruthenium precursor mixture;
[0041] (2) treating the obtained ruthenium precursor mixture in an air atmosphere at 450° C. for 3 h to obtain a supported ruthenium oxide catalyst;
[0042] (3) Mixing a supported ruthenium oxide catalyst, 0.6 g of chloroiridic acid, and 9.28 g of sodium nitrate in 40 g of ultrapure water, and evaporating the mixed solution with stirring at 80° C. to dryness to obtain an iridium precursor mixture;
[0043] (4) treating the iridium precursor mixture in an air atmosphere at 400° C. for 2 h to obtain a supported ruthenium-iridium catalyst;
[0044] (5) The supported ruthenium-iridium catalyst was washed in a 1M sodium hydroxide solution for 4 hours to detect the silicon-free content; then filtered and dried to obtain a honeycomb mesoporous iridium oxide-coated ruthenium oxide composite catalyst.
[0045] Example 3
[0046] In the preparation of the honeycomb composite ruthenium oxide / iridium oxide catalyst of Example 3, the molar ratio of iridium to ruthenium is 1:1; the molar ratio of mesoporous silica to ruthenium in ruthenium trichloride is 4:1; the molar ratio of the pro-oxidant sodium nitrate to ruthenium in ruthenium trichloride is 100:1; and the molar ratio of the pro-oxidant sodium nitrate to iridium in chloroiridic acid is 50:1. Specifically, the steps include:
[0047] (1) 0.25 g of ruthenium trichloride, 0.22 g of mesoporous silica support, and 7.78 g of sodium nitrate were mixed in 40 g of ultrapure water, the mixed solution was sonicated for 10 min, and stirred and evaporated to dryness at 80° C. to obtain a ruthenium precursor mixture;
[0048] (2) treating the ruthenium precursor mixture in an air atmosphere at 500° C. for 2 h to obtain a supported ruthenium oxide catalyst;
[0049] (3) Mixing a supported ruthenium oxide catalyst, 0.5 g of chloroiridic acid, and 3.9 g of sodium nitrate in 40 g of ultrapure water, and evaporating the mixed solution with stirring at 80° C. to dryness to obtain an iridium precursor mixture;
[0050] (4) treating the iridium precursor mixture in an air atmosphere at 450° C. for 2 h to obtain a supported ruthenium-iridium catalyst;
[0051] (5) The supported ruthenium-iridium catalyst was washed in a 1M sodium hydroxide solution for 5 hours, and the silicon-free content was detected; then, the catalyst was filtered and dried to obtain a honeycomb mesoporous iridium oxide-coated ruthenium oxide composite catalyst.
[0052] Example 4
[0053] In the preparation of the honeycomb composite ruthenium oxide / iridium oxide catalyst of Example 4, the molar ratio of iridium to ruthenium is 0.7:1; the molar ratio of mesoporous silica to ruthenium in ruthenium acetate is 3:1; the molar ratio of the pro-oxidant sodium nitrate to ruthenium in ruthenium acetate is 75:1; and the molar ratio of the pro-oxidant sodium nitrate to iridium in iridium trichloride is 75:1. Specifically, the steps include:
[0054] (1) 0.27 g of ruthenium acetate, 0.2 g of mesoporous silica support, and 7 g of sodium nitrate were mixed in 40 g of ultrapure water, the mixed solution was sonicated for 10 min, and stirred and evaporated to dryness at 80° C. to obtain a ruthenium precursor mixture;
[0055] (2) treating the ruthenium precursor mixture in an air atmosphere at 500° C. for 2 h to obtain a supported ruthenium oxide catalyst;
[0056] (3) Mixing a supported ruthenium oxide catalyst, 0.26 g of iridium trichloride, and 5.54 g of potassium nitrate in 40 g of ultrapure water, and evaporating the mixed solution with stirring at 80° C. to dryness to obtain an iridium precursor mixture;
[0057] (4) treating the iridium precursor mixture in an air atmosphere at 450° C. for 2 h to obtain a supported ruthenium-iridium catalyst;
[0058] (5) The supported ruthenium-iridium catalyst was washed in a 1M sodium hydroxide solution for 4 hours to detect the silicon-free content; then filtered and dried to obtain a honeycomb mesoporous iridium oxide-coated ruthenium oxide composite catalyst.
[0059] Example 5
[0060] In the preparation of the honeycomb composite ruthenium oxide / iridium oxide catalyst of Example 5, the molar ratio of iridium to ruthenium is 0.7:1; the molar ratio of mesoporous silica to ruthenium in ruthenium trichloride is 2:1; the molar ratio of the pro-oxidant sodium nitrate to ruthenium in ruthenium trichloride is 50:1; and the molar ratio of the pro-oxidant sodium nitrate to iridium in chloroiridic acid is 50:1. The steps are as follows:
[0061] (1) 0.3 g of ruthenium trichloride, 0.13 g of mesoporous silica support, and 4.67 g of sodium nitrate were mixed in 40 g of ultrapure water, the mixed solution was sonicated for 10 min, and stirred and evaporated to dryness at 80° C. to obtain a ruthenium precursor mixture;
[0062] (2) treating the ruthenium precursor mixture in an air atmosphere at 400° C. for 3 h to obtain a supported ruthenium oxide catalyst;
[0063] (3) Mixing a supported ruthenium oxide catalyst, 0.4 g of chloroiridic acid, and 3.1 g of sodium nitrate in 40 g of ultrapure water, and evaporating the mixed solution with stirring at 80° C. to dryness to obtain an iridium precursor mixture;
[0064] (4) treating the iridium precursor mixture in an air atmosphere at 450° C. for 2 h to obtain a supported ruthenium-iridium catalyst;
[0065] (5) The supported ruthenium-iridium catalyst was washed in a 1M sodium hydroxide solution for 4 hours to detect the silicon-free content; then filtered and dried to obtain a honeycomb mesoporous iridium oxide-coated ruthenium oxide composite catalyst.
[0066] Comparative Example 1
[0067] The difference between this comparative example and Example 1 is that only the iridium oxide catalyst is prepared, which includes the following steps:
[0068] (1) 1 g of chloroiridic acid and 11.6 g of sodium nitrate were mixed in 40 g of ultrapure water, and the mixed solution was stirred and evaporated to dryness at 80° C. to obtain an iridium precursor;
[0069] (2) treating the iridium precursor in an air atmosphere at 500° C. for 3 h to obtain an iridium oxide catalyst sample;
[0070] (3) The sample obtained in step (2) is washed with water, filtered, and dried to obtain an iridium oxide catalyst.
[0071] Comparative Example 2
[0072] The difference between this comparative example and Example 1 is that no silica template is used, and the comparative example specifically comprises the following steps:
[0073] (1) 0.2 g of ruthenium trichloride and 4.67 g of sodium nitrate were mixed in 40 g of ultrapure water, the mixed solution was sonicated for 10 min, and stirred and evaporated to dryness at 80° C. to obtain a ruthenium precursor;
[0074] (2) treating the ruthenium precursor in an air atmosphere at 400°C for 3 hours to obtain a ruthenium oxide catalyst;
[0075] (3) Mix the sample obtained in step 2, 0.39 g of iridium trichloride, and 7 g of sodium nitrate in 40 g of ultrapure water, and evaporate the mixed solution to dryness at 80° C. to obtain an iridium precursor mixture;
[0076] (4) The iridium precursor mixture is treated at 400° C. for 2 h, and then washed with water, filtered, and dried to obtain a composite catalyst of iridium oxide coated with ruthenium oxide.
[0077] Comparative Example 3
[0078] The difference between Comparative Example 3 and Example 1 is that only the iridium oxide catalyst with a honeycomb structure is formed. Specifically, the following steps are included:
[0079] (1) 0.647 g of iridium trichloride, 0.218 g of mesoporous silica support, and 7.74 g of sodium nitrate were mixed in 40 g of ultrapure water. The mixed solution was sonicated for 10 min and evaporated to dryness at 80°C.
[0080] (2) treating the evaporated precursor in air atmosphere at 400°C for 3 h;
[0081] (3) The sample obtained in step (2) was washed in a 1M sodium hydroxide solution for 4 hours to detect the silicon-free content; then, the sample was filtered and dried to obtain a mesoporous iridium oxide catalyst.
[0082] Performance test 1-Electrochemical performance
[0083] The electrochemical performance of the composite catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was tested, and the results are shown in Tables 2 and 3. Figure 1 shown.
[0084] Table 2 Electrochemical performance
[0085] sample Overpotential (mV) Comparative Example 1 350 Comparative Example 2 300 Comparative Example 3 310 Example 1 282 Example 2 280 Example 3 273 Example 4 270 Example 5 265
[0086] Combine Figure 1It can be seen that Examples 1-5 have a 2 Under these conditions, the electrolysis voltage of a single cell is 1.593V-1.617V, 2A / cm 2 Under these conditions, the electrolysis voltage of a single cell is 1.732V-1.756V, 3A / cm 2 Under these conditions, the electrolysis voltage of a single cell is 1.861V-1.885V.
[0087] Comparative Example 1 at 1A / cm 2 The electrolysis voltage of the lower cell is 1.725V, 2A / cm 2 Under these conditions, the electrolysis voltage of the single cell is 1.877V, 3A / cm 2 Under these conditions, the electrolysis voltage of a single cell is 2.025V.
[0088] Comparative Example 2 at 1A / cm 2 The lower electrolysis voltage is 1.683V, 2A / cm 2 The lower electrolysis voltage is 1.827V, 3A / cm 2 The lower electrolysis voltage is 1.96V.
[0089] Comparative Example 3 at 1A / cm 2 The lower electrolysis voltage is 1.707V, 2A / cm 2 The lower electrolysis voltage is 1.849V, 3A / cm 2 The lower electrolysis voltage is 1.986V.
[0090] That is, through comparison, it is found that the catalytic activity of the samples of Examples 1-5 is significantly better than that of the comparative example, especially at high current density, the advantage is more obvious.
[0091] From Table 2, it can be seen that the catalyst overpotentials of Examples 1-5 are no higher than 282 mV, and the lowest is only 265 mV, while in the comparative example, the oxygen evolution overpotential is as high as 350 mV.
[0092] Performance Testing-Stability
[0093] The samples of Example 1 and Comparative Example 3 were subjected to stability tests. Both samples were tested at 1A / cm 2 The single cell test was carried out for 100 hours at a current density of 80°C and a temperature of 80°C, and the real-time voltage value was detected.
[0094] The results are as follows Figure 2 As shown, within the 100-hour test time, the performance of Example 1 is substantially unchanged, while the voltage of Comparative Example 3 decays by 25 mV. From the long-term test, it can be seen that the stability of Example 1 is significantly improved compared with Comparative Example 3.
[0095] In addition to the above examples, it should be noted that the molar ratio of iridium to ruthenium in the catalyst prepared by the present invention can also be (0.4-0.6):(0.6-0.4), the molar mass ratio of the co-oxidant to ruthenium or iridium can also be (50-100):1, and the molar ratio of mesoporous silica to ruthenium can also be (2-4):1. In other words, the claimed technical efficacy of the present invention can be achieved by using the preparation process of the present invention and within the specified parameter ranges, and thus no further examples are provided for further demonstration.
Claims
1. A honeycomb composite ruthenium oxide / iridium oxide catalyst, characterized in that: Prepared by the following steps: (1) mixing mesoporous silica, a ruthenium source, a co-oxidant, and a solvent, and evaporating to dryness to obtain a ruthenium precursor mixture; (2) heat-treating the ruthenium precursor mixture in an air atmosphere at 400-500° C. for 2-3 hours to obtain a supported ruthenium oxide catalyst; (3) mixing a supported ruthenium oxide catalyst, an iridium source, a co-oxidant, and a solvent, and evaporating the mixture to obtain an iridium precursor mixture; (4) heat-treating the iridium precursor mixture in an air atmosphere at 400-500° C. for 2-3 h to obtain a supported ruthenium-iridium catalyst; (5) After the supported ruthenium-iridium catalyst is alkaline-washed to remove the mesoporous silica, it is washed, filtered and dried to obtain a honeycomb-type iridium oxide-coated ruthenium oxide composite catalyst.
2. The honeycomb-type composite ruthenium oxide / iridium oxide catalyst according to claim 1, characterized in that: The molar ratio of iridium to ruthenium in the catalyst is (0.4-0.6):(0.6-0.4).
3. The honeycomb type composite ruthenium oxide / iridium oxide catalyst according to claim 1, characterized in that: In step (1), the pore size of the mesoporous silica is 5-7 nm.
4. The honeycomb type composite ruthenium oxide / iridium oxide catalyst according to claim 1, characterized in that: In step (1), the ruthenium source is ruthenium chloride, ruthenium nitrate or ruthenium acetate, and the molar ratio of mesoporous silica to ruthenium in the ruthenium source is (2-4):
1.
5. The honeycomb type composite ruthenium oxide / iridium oxide catalyst according to claim 1, characterized in that: In step (1), the co-oxidant includes sodium nitrate or potassium nitrate, and the molar ratio of the co-oxidant to the ruthenium in the ruthenium source is (50-100):
1.
6. The honeycomb type composite ruthenium oxide / iridium oxide catalyst according to claim 1, characterized in that: In step (3), the iridium source is iridium trichloride or chloroiridic acid.
7. The honeycomb type composite ruthenium oxide / iridium oxide catalyst according to claim 1, characterized in that: In step (3), the co-oxidant includes sodium nitrate or potassium nitrate, and the molar ratio of the co-oxidant to the iridium in the iridium source is (50-100):1.