Process for the preparation of a catalyst and use thereof
By mixing metal oxide powder with water-soluble salt as a support template for electrochemical reduction, the problem of insufficient conductivity of the support is solved, and a highly active and stable supported catalyst is prepared, which is suitable for proton exchange membrane water electrolysis reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAMEN ZIJIN NEW ENERGY & NEW MATERIAL TECH CO LTD
- Filing Date
- 2026-04-01
- Publication Date
- 2026-05-29
AI Technical Summary
In existing electrochemical reduction methods for catalyst preparation, the insufficient conductivity of the support affects the performance and efficiency of the catalyst.
Metal oxide powder is mixed with water-soluble salt as a support template for electrochemical reduction to form conductive channels. The water-soluble salt is then removed by washing with water to obtain a supported catalyst. The iridium precursor is reduced to highly active metallic iridium on the surface of the metal oxide, and oxygen vacancies and defect states are formed on the support surface, which improves conductivity and catalytic performance.
The conductivity and catalytic activity of the catalyst were improved, resulting in a highly dispersed and stable supported iridium metal catalyst suitable for proton exchange membrane water electrolysis.
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Figure CN122105469A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, and relates to a method for preparing a catalyst and its application. Background Technology
[0002] Proton exchange membrane water electrolysis for hydrogen production is considered a core pathway to achieving a green hydrogen economy due to its advantages such as fast response speed and high hydrogen purity. However, the oxygen evolution reaction at the anode is kineticly slow and requires operation in a strongly acidic, high-potential environment, thus heavily relying on iridium-based catalysts. Currently, the most widely used commercial iridium-based catalyst is iridium oxide.
[0003] Electrochemical reduction is an effective method for preparing supported catalysts, enabling the one-step loading, reduction, and nucleation growth of metal catalytic active components, and allowing for precise control of catalyst structure and performance. However, the electrochemical reduction process requires high conductivity; supports with insufficient conductivity are detrimental to the electrochemical reduction process.
[0004] Therefore, existing methods for preparing catalysts by electrochemical reduction require further optimization. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a method for preparing a catalyst and its application.
[0006] The technical solution of the present invention is as follows:
[0007] A method for preparing a catalyst includes the following steps: Metal oxide powder and water-soluble salt are mixed evenly to obtain a first mixed powder; the first mixed powder is mixed evenly with an aqueous solution of iridium precursor and dried to obtain a second mixed powder; the second mixed powder is pressed into a pre-formed electrode body. The metal oxide powder is a semiconductor material; The preformed electrode body is used as a cathode and undergoes electrochemical reduction treatment in an electrolyte to obtain a composite material. The composite material is immersed in deionized water to remove the water-soluble salts, and then dried to obtain the catalyst.
[0008] Preferably, the metal oxide powder is selected from one or more of titanium dioxide, zinc oxide, tin dioxide, nickel oxide, and cobalt tetroxide.
[0009] Preferably, the weight ratio of the metal oxide powder to the water-soluble salt is 1:1-5; The water-soluble salt is electrochemically inert during the electrochemical reduction treatment.
[0010] More preferably, the water-soluble salt is selected from one or more of chlorides, sulfates, nitrates and phosphates.
[0011] Preferably, the concentration of the iridium precursor aqueous solution is 5-20 wt%; The iridium precursor in the aqueous solution of the iridium precursor is selected from one or more of iridium chloro-iridium acid, sodium iridium chloro-iridium, potassium iridium chloro-iridium, ammonium iridium chloro-iridium, iridium trichloride, iridium nitrate, and iridium acetate. The saturated water absorption volume of the first mixed powder is not less than the volume of the aqueous solution of the iridium precursor.
[0012] More preferably, the saturated water absorption volume of the first mixed powder is equal to the volume of the iridium precursor aqueous solution.
[0013] Preferably, the pressing pressure is 5-30 MPa and the holding time is 20-120 s; The preformed electrode body is in the shape of a sheet, rod, or block.
[0014] Preferably, the electrolyte is selected from an aqueous solution of inorganic salts with a concentration of 0.1-1 mol / L; The inorganic salt in the inorganic salt aqueous solution is selected from one or more of sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, magnesium sulfate, magnesium chloride, zinc sulfate, zinc chloride, potassium nitrate, and sodium nitrate.
[0015] Preferably, when the electrochemical reduction treatment is a potentiostatic method, the cathode potential relative to the saturated calomel electrode potential is -0.4 V to -1.0 V; When the electrochemical reduction treatment is a pulse electrodeposition method, the pulse turn-on potential relative to the saturated calomel electrode potential is -0.4 V to -1.0 V, the turn-off potential is the open circuit potential or 0 V, the turn-on time is 0.1-2 s, and the turn-off time is 2-20 s.
[0016] The application of a catalyst obtained by the preparation method described in any of the above embodiments as a supported proton exchange membrane water electrolysis catalyst.
[0017] The beneficial effects of this invention are: (1) In this invention, metal oxide powder and water-soluble salt are mixed, and the pressed water-soluble salt is used as a carrier template to form a temporary, through-hole ion-conducting channel. This allows the metal oxide pellet, which originally had limited conductivity, to be connected to the circuit as a cathode, providing a prerequisite for the electrochemical reaction and promoting the complete reduction of the iridium precursor. After the electrochemical reduction reaction is completed, the water-soluble salt can be released by simple water washing to release the carrier and catalytically active components, thus obtaining a supported catalyst.
[0018] (2) During the electrochemical reduction process, iridium precursor ions gain electrons on the surface of titanium dioxide particles and are reduced to highly active metallic iridium. At the same time, the strong cathodic reduction atmosphere can also reduce part of the surface of the metal oxide support, generating a support rich in oxygen vacancies and defect states, which greatly improves the conductivity of the support, thereby optimizing the electron transport capacity and catalytic performance of the catalyst. Attached Figure Description
[0019] Figure 1 The membrane electrode performance results of the catalyst prepared in Example 1 are compared with those of a commercial catalyst.
[0020] Figure 2 The results show the acidic OER performance of the catalyst prepared in Example 2. Detailed Implementation
[0021] The technical solution of the present invention will be further explained and described below through specific embodiments.
[0022] To address the problem of insufficient conductivity of the support in the electrochemical reduction method for preparing supported catalysts in existing technologies, this invention proposes a method for preparing a catalyst, comprising the following steps: Metal oxide powder and water-soluble salt are mixed evenly to obtain a first mixed powder; the first mixed powder is mixed evenly with an aqueous solution of iridium precursor and dried to obtain a second mixed powder; the second mixed powder is pressed into a pre-formed electrode body. Metal oxide powder is a semiconductor material; The preformed electrode body is used as the cathode and undergoes electrochemical reduction treatment in the electrolyte to obtain a composite material. The composite material is immersed in deionized water to remove water-soluble salts, then dried to obtain the catalyst.
[0023] The present invention uses water-soluble salt as a carrier template and has the following characteristics: (1) Water-soluble salt has good conductivity, which can improve the conductivity of the electrochemical reduction process, improve the reduction effect of iridium precursor, and obtain iridium catalytic active components with better dispersion and higher activity; (2) Water-soluble salt acts as a temporary binder, ensuring that the metal oxide powder can be pressed and molded. Water-soluble salt is also easy to remove by washing with water, leaving the carrier and catalytic active components to form a supported catalyst; (3) During the electrochemical reduction process, the water-soluble salt on the surface of the preformed electrode body will be gradually dissolved by the electrolyte, constructing an initial channel, which is conducive to the penetration of the electrolyte. However, the water-soluble salt inside the preformed electrode body is still retained and maintains the function of the conductive channel.
[0024] In the electrochemical reduction process of iridium precursor, metal oxide powder serves as a support, and part of the surface of the metal oxide powder is also reduced, forming oxygen vacancies and defect states. This results in a support with oxygen vacancies and defect states, which improves the activity of the support and its interaction with the catalytically active components. As a result, a supported metal iridium catalyst with high activity, high dispersibility and high stability is obtained under mild conditions and without the need for high-temperature treatment.
[0025] In some embodiments, the metal oxide powder is selected from one or more of titanium dioxide, zinc oxide, tin dioxide, nickel oxide, and cobalt tetroxide. That is, in this invention, the catalyst support can be titanium dioxide, zinc oxide, tin dioxide, nickel oxide, and cobalt tetroxide, etc., which are semiconductor materials. For example, when the metal oxide is titanium dioxide, the defect state formed is Ti. 3+ When the metal oxide is zinc oxide, various defect states can be formed, such as zinc vacancies and zinc interstitial atoms; when the metal oxide is nickel oxide, various defect states can be formed, such as Ni... 3+ Nickel vacancies. The formation of defect states in metal oxides is conducive to the formation of strong anchoring points, resulting in higher dispersion and greater stability when iridium is loaded. Defect states can also act as electron channels, increasing the electron transport speed between the carrier and iridium.
[0026] The preparation method of the present invention is not suitable for carriers with poor conductivity or even insulation, such as silicon dioxide and alumina.
[0027] In some embodiments, the weight ratio of metal oxide powder to water-soluble salt is 1:1-5; Water-soluble salts are electrochemically inert during electrochemical reduction treatment.
[0028] For example, the weight ratio of metal oxide powder to water-soluble salt can be any value or any value between 1:1, 1:2, 1:3, 1:4, 1:5, etc. The water-soluble salt is electrochemically inert during electrochemical reduction treatment and does not undergo oxidation or reduction reactions.
[0029] In some embodiments, the water-soluble salt is selected from one or more of chlorides, sulfates, nitrates, and phosphates. To improve the pressing effect, the particle size of the water-soluble salt may not exceed 200 mesh.
[0030] In some embodiments, the concentration of the iridium precursor aqueous solution is 5-20 wt%; The iridium precursor in the aqueous solution of the iridium precursor is selected from one or more of iridium chloroic acid, sodium iridium chloroic acid, potassium iridium chloroic acid, ammonium iridium chloroic acid, iridium trichloride, iridium nitrate, and iridium acetate; The saturated water absorption volume of the first mixed powder is not less than the volume of the iridium precursor aqueous solution.
[0031] The concentration of an iridium precursor aqueous solution refers to the effective concentration of the iridium precursor within it. For example, if the iridium precursor is a hydrate, the concentration is calculated based on the iridium precursor content within the hydrate. Similarly, if the iridium precursor is hydrated chloroiridic acid, the concentration of the iridium precursor aqueous solution refers to the concentration of chloroiridic acid. For instance, the concentration of an iridium precursor aqueous solution can be any value or any value between 5%, 6%, 7%, 8%, 9%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, and 20wt%.
[0032] Furthermore, the saturated water absorption volume of the first mixed powder does not exceed three times the volume of the iridium precursor aqueous solution. If the volume of the iridium precursor aqueous solution is too small, it is not conducive to the full and uniform mixing of the first mixed powder and the iridium precursor aqueous solution. Even further, the saturated water absorption volume of the first mixed powder does not exceed 1.5 times the volume of the iridium precursor aqueous solution.
[0033] The saturated water absorption volume of the first mixed powder refers to the minimum volume of water required to completely wet a unit mass of the first mixed powder at room temperature, ensuring no free water remains. The saturated water absorption volume of the first mixed powder is not less than the volume of the iridium precursor aqueous solution. This ensures the first mixed powder completely absorbs the iridium precursor aqueous solution, avoiding problems such as the dissolution of water-soluble salts due to excessive iridium precursor aqueous solution, and the powder becoming too wet before pressing and molding, making it difficult to press. The mixing of the first mixed powder and the iridium precursor aqueous solution can be achieved by adding the iridium precursor aqueous solution to the rolling first mixed powder through methods such as dripping or spraying, ensuring uniform mixing. Subsequent drying can be carried out at 50-100℃.
[0034] In some embodiments, the saturated water absorption volume of the first mixed powder is equal to the volume of the iridium precursor aqueous solution, i.e., an equal-volume impregnation method. The first mixed powder can absorb as much iridium precursor aqueous solution as possible, which is beneficial for the full and uniform mixing of the first mixed powder and the iridium precursor aqueous solution, and also helps to increase the iridium precursor content, ultimately increasing the iridium content in the supported catalyst.
[0035] In some embodiments, the compression molding pressure is 5-30 MPa, and the holding time is 20-120 s; The preformed electrode body can be in the shape of a sheet, rod, or block.
[0036] In some embodiments, the electrolyte is selected from an aqueous solution of inorganic salts with a concentration of 0.1-1 mol / L; The inorganic salt in the aqueous solution is selected from one or more of sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, magnesium sulfate, magnesium chloride, zinc sulfate, zinc chloride, potassium nitrate, and sodium nitrate. These inorganic salts exhibit good electrochemical stability and conductivity, making them suitable as electrolytes. For example, the concentration of the electrolyte can be any value or any value between 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, and 1 mol / L.
[0037] The electrochemical reduction treatment of the present invention can be performed using a potentiostatic method or a pulsed electrodeposition method. In some embodiments, when the electrochemical reduction treatment is performed using a potentiostatic method, the cathode potential relative to the saturated calomel electrode potential is -0.4 V to -1.0 V; When the electrochemical reduction treatment is performed by pulse electrodeposition, the pulse turn-on potential is -0.4V to -1.0V relative to the saturated calomel electrode potential, the turn-off potential is the open circuit potential or 0V, the turn-on time is 0.1-2s, and the turn-off time is 2-20s.
[0038] On the other hand, the present invention also proposes an application of the catalyst obtained by the preparation method described in any of the above embodiments as a supported proton exchange membrane electrolysis catalyst. The supported catalyst obtained by the present invention exhibits high dispersion of the catalytically active component (iridium), high activity of the support, good conductivity, and high activity and stability, and can be used as a supported proton exchange membrane electrolysis catalyst.
[0039] The technical solution of the present invention will be further described and illustrated below with reference to various embodiments. Unless otherwise specified, the parts mentioned in the following embodiments are parts by weight.
[0040] Example 1 Weigh 2g of titanium dioxide powder (P25) and 4g of sodium chloride powder (analytical grade, 400 mesh) and place them in an agate mortar. Grind and mix for 10 minutes to obtain the first mixed powder composed of titanium dioxide and sodium chloride.
[0041] An iridium precursor solution and a first mixed powder were mixed using an equal-volume impregnation method. 5 mL of ultrapure water was used to dissolve 1.05 g of chloroiridium hexahydrate to prepare an iridium precursor solution. The iridium precursor solution was added dropwise to the mixed powder while continuously stirring during the addition process, resulting in a moist composite powder. The composite powder was then dried in an oven at 80°C for 6 hours to obtain a dry second mixed powder composed of titanium dioxide, sodium chloride, and chloroiridium acid.
[0042] The second mixed powder is loaded into a tableting mold and pressed under a pressure of 10 MPa for 60 seconds to form a sheet electrode.
[0043] A three-electrode system was constructed using the aforementioned sheet-like electrode as the working electrode (cathode), a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrolyte was a 0.5 mol / L sodium sulfate aqueous solution (purged with nitrogen for 30 minutes to remove oxygen). Electrochemical reduction treatment was performed using pulsed electrodeposition, with the following pulse parameters set: on-potential -0.6 V (vs. SCE), on-time 1 s, off-potential 0 V, off-time 10 s, and total deposition time 30 min. After the electrochemical reaction was completed, a composite material composed of defective titanium dioxide, sodium chloride, and iridium was obtained.
[0044] The composite material was removed and immersed in ultrapure water, then subjected to ultrasonic treatment at 200W for 10 minutes to ensure complete dissolution of sodium chloride and thorough dispersion of the composite material. The suspension was collected and centrifuged at high speed (10,000 rpm, 10 minutes), and the supernatant was discarded. The washing and centrifugation process was repeated until no white precipitate was detected in the supernatant using silver nitrate solution, and the solid precipitate was collected.
[0045] The solid precipitate was transferred to a vacuum drying oven and dried at 60°C for 12 hours to obtain the catalyst, which is a supported catalyst of iridium supported on titanium dioxide with high conductivity defects.
[0046] Membrane electrode preparation and testing method: The catalyst in this embodiment was prepared with an active area of 25 cm². 2 The membrane electrode was used to control the iridium loading at the anode to be 0.5 mg / cm³. 2 The cathode platinum loading is 0.3 mg / cm³. 2 The membrane electrode was assembled onto a standard test fixture, and purified water was passed through it at a flow rate of 100 mL / min. The voltage at different current densities was measured when the fixture temperature was 60°C.
[0047] Figure 1 The membrane electrode performance test curves of the catalyst prepared in this embodiment show that, at the same current density, the catalyst prepared in this embodiment has a lower voltage than the commercial catalyst (Heraene noble metal, H2EL-45IrO-S60), indicating that the catalyst prepared in this embodiment has higher catalytic activity.
[0048] Comparative Example 1 The difference between this comparative example and Example 1 is that in Example 1, when the first mixed powder and the iridium precursor solution were mixed by an equal-volume impregnation method, the first mixed powder was replaced with titanium dioxide powder P25. That is, sodium chloride is not added in this comparative example, and the step of ultrasonically cleaning sodium chloride is omitted, while the remaining steps remain unchanged.
[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that in Example 1, titanium dioxide powder was replaced with an equal weight of silicon dioxide powder. The remaining steps remain unchanged.
[0050] Example 2 Weigh 1g of titanium dioxide powder (P25) and 1g of sodium nitrate powder (analytical grade, 800 mesh) and place them in an agate mortar. Grind and mix for 10 minutes to obtain the first mixed powder composed of titanium dioxide and sodium nitrate.
[0051] An iridium precursor solution and a first mixed powder were mixed using an equal-volume impregnation method. 3 mL of ultrapure water was used to dissolve 1.1 g of ammonium chloroiridate to prepare an iridium precursor solution. The iridium precursor solution was then uniformly sprayed onto the first mixed powder using a spray device to obtain a moist composite powder. The composite powder was dried in an oven at 100°C for 1 hour to obtain a dry second mixed powder composed of titanium dioxide, sodium nitrate, and the iridium precursor.
[0052] The second mixed powder is loaded into a mold and pressed into a rod-shaped electrode body under a pressure of 5 MPa for 120 seconds.
[0053] A three-electrode system was constructed using the aforementioned rod-shaped electrode as the working electrode (cathode), a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrolyte was a 1.0 mol / L potassium nitrate solution (oxygenated by purging with nitrogen gas). Electrochemical reduction treatment was performed using pulsed electrodeposition, with the following pulse parameters set: on-potential -0.4 V (vs. SCE), on-time 0.1 s, off-time 20 s, and total deposited charge controlled at 1 C. After the electrochemical reaction was completed, a composite material composed of defective titanium dioxide, sodium nitrate, and iridium was obtained.
[0054] The composite material was immersed in ultrapure water and dispersed by ultrasonic treatment (500W, 30 min). The resulting suspension was collected and washed by high-speed centrifugation (12000 rpm, 10 min), and the supernatant was discarded. The washing and centrifugation were repeated until no white precipitate was detected in the supernatant using silver nitrate solution, and the solid precipitate was collected.
[0055] The above solid precipitate was freeze-dried under vacuum to obtain the catalyst, which is a supported catalyst of metallic iridium supported on titanium dioxide with high conductivity defects.
[0056] Acidic OER performance testing method: The testing equipment consisted of an electrochemical workstation (Chenhua CHI660E) and a rotating disk electrode (PINE, 0.196cm). 2 (Glassy carbon electrode). The catalyst was prepared as a slurry, and 6 μL of the slurry was dropped onto a rotating disk electrode, with a catalyst loading of 0.2 mg / cm³. 2Air dry naturally. Use 0.1M perchloric acid as the electrolyte, a standard hydrogen electrode as the reference electrode, and a carbon rod as the counter electrode. During testing, rotate the sample electrode at 1600 rpm, set the LSV test program to a scan rate of 2 mV / s, and repeat the test until the LSV curves coincide. Take the data from the last cycle after coincidence. The overpotential is calculated as the current density is 10 mA / cm². 2 The corresponding voltage value is reduced by 1.23V.
[0057] Figure 2 The acidic OER performance results of the catalyst prepared in this embodiment show that the catalyst at 10 mA / cm 2 The overpotential at the current density is only 231mV, which is much lower than the 301mV overpotential of the commercial catalyst (Heraeste precious metal, H2EL-45IrO-S60), indicating that the catalyst in this embodiment has high catalytic activity.
[0058] Example 3 The difference between this embodiment and Embodiment 2 is that in Embodiment 2, the saturated water absorption volume of the first mixed powder was adjusted to 1.5 times the volume of the iridium precursor solution. The remaining steps remained unchanged.
[0059] Example 4 The difference between this embodiment and Embodiment 2 is that in Embodiment 2, the saturated water absorption volume of the first mixed powder was adjusted to three times the volume of the iridium precursor solution. The remaining steps remained unchanged.
[0060] Example 5 Weigh 1.5g of rutile titanium dioxide powder and 7.5g of potassium chloride powder (analytical grade, 200 mesh) and place them in an agate mortar. Grind and mix for 10 minutes to obtain the first mixed powder composed of titanium dioxide and potassium chloride.
[0061] An iridium precursor solution and a first mixed powder were mixed using an equal-volume impregnation method. 8 mL of ultrapure water was used to dissolve 1.3 g of chloroiridium hexahydrate to prepare an iridium precursor solution. This iridium precursor solution was added dropwise to the first mixed powder with continuous stirring until the solution was completely absorbed, resulting in a moist composite powder. The composite powder was then dried in a 50°C oven for 12 hours to obtain a dry second mixed powder composed of titanium dioxide, potassium chloride, and the iridium precursor.
[0062] The second mixed powder is loaded into a mold and pressed into a block electrode body under a pressure of 30 MPa for 30 seconds.
[0063] A three-electrode system was constructed using the aforementioned bulk electrode as the working electrode (cathode), a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrolyte was a 0.1 mol / L potassium sulfate solution (after being purged with nitrogen gas for deoxygenation). Electrochemical reduction was performed using a potentiostatic method, with a cathode potential of -1.0 V (vs. SCE) and a reduction time of 20 min. After the electrochemical reaction was completed, a composite material composed of defective titanium dioxide, potassium chloride, and iridium was obtained.
[0064] The composite material was immersed in ultrapure water and dispersed by ultrasonic treatment (300W, 12 min). The resulting suspension was collected and washed by high-speed centrifugation (12000 rpm, 10 min), and the supernatant was discarded. The washing and centrifugation were repeated until no white precipitate was detected in the supernatant using silver nitrate solution, and the solid precipitate was collected.
[0065] The above solid precipitate was dried overnight in an oven at 70°C to obtain the catalyst, which is a supported catalyst of metallic iridium supported on titanium dioxide with high conductivity defects.
[0066] Example 6 The difference between this embodiment and Embodiment 5 is that in Embodiment 5, rutile titanium dioxide powder is replaced with an equal weight of zinc oxide powder. The remaining steps remain unchanged.
[0067] Example 7 The difference between this embodiment and Embodiment 5 is that in Embodiment 5, rutile titanium dioxide powder is replaced with an equal weight of nickel oxide powder. The remaining steps remain unchanged.
[0068] Performance testing: The overpotential was tested according to the method in Example 2.
[0069] Catalyst yield: Calculated as follows: Catalyst yield = (catalyst weight / (iridium precursor weight × iridium percentage + support powder weight)) × 100%.
[0070] The results are shown in Table 1 below.
[0071] Table 1
[0072] As shown in Table 1 above, the catalyst obtained by the preparation method of the present invention has high catalytic activity and low overpotential. Comparing Example 1 and Comparative Example 1, it can be seen that the use of water-soluble salt improves the conductivity of the electrochemical reaction process, which is beneficial to the complete reduction of iridium; otherwise, the iridium reduction would be insufficient, and the catalyst yield would be low. Comparing Example 1 and Comparative Example 2, it can be seen that using electrically insulating silica powder as a support, although improving the degree of iridium reduction and catalyst yield due to the conductivity of the water-soluble salt, results in fewer oxygen vacancies and defects formed on the silica, leading to lower catalyst activity.
[0073] After the acidic OER test of the catalyst in Example 2 was performed, it was cleaned and dried, and then subjected to a plating test. The overpotentials of the second, third, fourth and fifth tests were measured to be 234 mV, 235 mV, 230 mV and 234 mV, respectively, indicating that the catalyst has good stability.
[0074] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a catalyst, characterized in that, Includes the following steps: Metal oxide powder and water-soluble salt are mixed evenly to obtain a first mixed powder; the first mixed powder is mixed evenly with an aqueous solution of iridium precursor and dried to obtain a second mixed powder; the second mixed powder is pressed into a pre-formed electrode body. The metal oxide powder is a semiconductor material; The preformed electrode body is used as a cathode and undergoes electrochemical reduction treatment in an electrolyte to obtain a composite material. The composite material is immersed in deionized water to remove the water-soluble salts, and then dried to obtain the catalyst.
2. The method for preparing the catalyst according to claim 1, characterized in that, The metal oxide powder is selected from one or more of titanium dioxide, zinc oxide, tin dioxide, nickel oxide, and cobalt tetroxide.
3. The method for preparing the catalyst according to claim 1, characterized in that, The weight ratio of the metal oxide powder to the water-soluble salt is 1:1-5; The water-soluble salt is electrochemically inert during the electrochemical reduction treatment.
4. The method for preparing the catalyst according to claim 3, characterized in that, The water-soluble salt is selected from one or more of chlorides, sulfates, nitrates, and phosphates.
5. The method for preparing the catalyst according to claim 1, characterized in that, The concentration of the iridium precursor aqueous solution is 5-20 wt%; The iridium precursor in the aqueous solution of the iridium precursor is selected from one or more of iridium chloro-iridium acid, sodium iridium chloro-iridium, potassium iridium chloro-iridium, ammonium iridium chloro-iridium, iridium trichloride, iridium nitrate, and iridium acetate. The saturated water absorption volume of the first mixed powder is not less than the volume of the aqueous solution of the iridium precursor.
6. The method for preparing the catalyst according to claim 5, characterized in that, The saturated water absorption volume of the first mixed powder is equal to the volume of the aqueous solution of the iridium precursor.
7. The method for preparing the catalyst according to claim 1, characterized in that, The pressing pressure is 5-30MPa, and the holding time is 20-120s; The preformed electrode body is in the shape of a sheet, rod, or block.
8. The method for preparing the catalyst according to claim 1, characterized in that, The electrolyte is selected from inorganic salt aqueous solutions with a concentration of 0.1-1 mol / L; The inorganic salt in the inorganic salt aqueous solution is selected from one or more of sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, magnesium sulfate, magnesium chloride, zinc sulfate, zinc chloride, potassium nitrate, and sodium nitrate.
9. The method for preparing the catalyst according to claim 1, characterized in that, When the electrochemical reduction treatment is a potentiostatic method, the cathode potential relative to the saturated calomel electrode potential is -0.4 V to -1.0 V; When the electrochemical reduction treatment is a pulse electrodeposition method, the pulse turn-on potential relative to the saturated calomel electrode potential is -0.4V to -1.0V, the turn-off potential is the open circuit potential or 0V, the turn-on time is 0.1-2s, and the turn-off time is 2-20s.
10. The application of a catalyst obtained by the preparation method according to any one of claims 1-9, characterized in that, As a catalyst for supported proton exchange membrane water electrolysis.