Electrolyzed water catalyst as well as preparation method and application thereof
Nanoscale iridium oxide and ruthenium oxide catalysts were prepared by flame spray combustion, which solved the problems of catalyst activity and stability in water electrolysis for hydrogen production, and realized an efficient and environmentally friendly water electrolysis hydrogen production process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PAN ASIAN MICROVENT TECH JIANGSU CORP
- Filing Date
- 2026-01-21
- Publication Date
- 2026-05-12
AI Technical Summary
In existing water electrolysis hydrogen production technologies, the slow kinetics of the oxygen evolution reaction at the anode and the instability of the catalyst limit the hydrogen production efficiency. Traditional catalyst preparation processes are complex and environmentally unfriendly, and the uneven distribution of catalyst particles leads to poor activity and durability.
Iridium oxide (IrOx) and/or ruthenium oxide (RuOx) catalysts are prepared by flame spray combustion. By controlling the volumetric flow ratio of fuel gas and oxidant, catalysts with nanoscale particle size and stable lattice structure with oxygen vacancies are generated at high temperature, simplifying the preparation process and reducing the amount of precious metals used.
A highly active and stable water electrolysis catalyst was developed, which reduced the ohmic resistance, increased the specific surface area and electronic conductivity of the catalyst, extended the catalyst's lifespan, simplified the preparation process, and reduced the environmental impact.
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Figure CN122013221A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst preparation, and in particular to a highly active and stable water electrolysis catalyst for the oxygen evolution reaction at the anode of proton exchange membrane water electrolysis, and its preparation method. Background Technology
[0002] Hydrogen, as a green energy source, produces only water as a byproduct, making it a clean and renewable energy source for the new era. Electrolysis of water to produce hydrogen is one of the most efficient methods due to its high energy conversion efficiency.
[0003] However, the commercial application of this technology is severely limited by the slow kinetics of the oxygen evolution reaction (OER). The OER involves four consecutive proton-coupled electron transfer processes, and its inherently high energy barrier leads to a low reaction rate and a large overpotential, which directly limits the efficiency of the entire water electrolysis hydrogen production process.
[0004] While oxygen evolution reaction can achieve higher energy efficiency and lower ohmic loss under acidic conditions, it places extremely high demands on the activity and stability of the catalyst.
[0005] Currently, the commonly used catalysts for the oxygen evolution reaction (OER) are iridium oxide (IrOx) and ruthenium oxide (RuOx), which are typically prepared via wet chemical reduction. This method has significant drawbacks: firstly, the process is complex and lengthy, requiring multiple steps including stirring, filtration, drying, calcination, and pulverization; secondly, mass production consumes large amounts of water or solvents and generates filtrate to be treated, creating environmental pressure; and most importantly, the catalyst particles prepared by this method are typically amorphous, with large and unevenly distributed particle sizes, resulting in poor catalytic activity and durability, making it difficult to meet the requirements for efficient and stable electrolytic hydrogen production. Summary of the Invention
[0006] The main technical problem solved by this invention is to provide an electrolytic water catalyst and its preparation method that is simple in process, environmentally friendly, and can simultaneously achieve high activity and excellent stability.
[0007] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide an electrolytic water catalyst, wherein the catalyst comprises iridium oxide (IrOx) and / or ruthenium oxide (RuOx), wherein 0 < x < 2, and the catalyst has a stable crystal lattice structure and nanoscale particle size.
[0008] Among them, the sub-stoichiometric property with 0 < x < 2 means that a rich amount of oxygen vacancies are successfully introduced into the catalyst lattice, which not only enhances the intrinsic catalytic activity but also significantly improves the electronic conductivity, thereby reducing the ohmic internal resistance and making it suitable for the oxygen evolution reaction (OER) in electrolytic water. At the same time, the stable lattice structure and nano-scale particle size ensure that the catalyst has a long lifespan and a high specific surface area in a harsh anodic environment, fully exposing the active sites.
[0009] In a preferred embodiment of the present invention, the catalyst further includes a mixture composed of one or more of titanium oxide (TiOx), cerium oxide (CeOx), manganese oxide (MnOx), and zirconium oxide (ZrOx) as a conductive carrier, where 0 < x < 2. The carrier is used to disperse IrOx or RuOx, increasing the active sites. The present invention may also include a carrier having oxygen vacancies, which can not only effectively disperse and anchor the active components, prevent their agglomeration, and increase the number of active sites, but also utilize the conductivity of the carrier itself to form a synergistic effect, thereby reducing the loading of expensive Ir and Ru while ensuring excellent performance, achieving cost reduction and efficiency improvement.
[0010] In a preferred embodiment of the present invention, the TiOx, CeOx, MnOx, or ZrOx is derived from a titanium-, cerium-, manganese-, or zirconium-containing compound, including one or more of titanium isopropoxide, titanium tetrachloride, cerium nitrate, cerium acetate, cerium chloride, manganese nitrate, manganese tetrachloride, zirconium n-butoxide, or zirconium chloride.
[0011] In a preferred embodiment of the present invention, the range of x is 0.5 < x < 1.9; the average particle size of the nano-scale particle size is between 3 and 8 nanometers. The preferred range of 0.5 < x < 1.9 enables the concentration of oxygen vacancies to be in the optimal range, thereby obtaining the optimal catalytic activity and conductivity; the average particle size of 3 - 8 nanometers ensures a large specific surface area and uniform physical properties.
[0012] Another technical solution adopted by the present invention is: to provide a preparation method of an electrolytic water catalyst, including the following steps:
[0013] (1) Introduce fuel gas and oxidant into a flame burner and ignite for combustion;
[0014] (2) Control the volume flow ratio of the fuel gas and the oxidant to form a reducing atmosphere in the combustion chamber, which is sufficient to generate an oxide with oxygen vacancies from the metal compound under high-temperature combustion but not sufficient to reduce it to the metal单质;
[0015] (3) Introduce the iridium- or ruthenium-containing compound solution into the combustion chamber by spraying for combustion reaction to generate the iridium oxide (IrOx) or ruthenium oxide (RuOx), where 0 < x < 2;
[0016] (4) Collect the products after the combustion reaction to obtain the water electrolysis catalyst.
[0017] This preparation method has significant advantages such as simple process and environmental friendliness. It adopts a one-step continuous synthesis process, integrating multiple complex steps in the traditional wet process into a single reactor and completing them instantly. This greatly simplifies the process flow, improves production efficiency, facilitates large-scale scaling, and avoids the generation of large amounts of waste liquid.
[0018] In a preferred embodiment of the present invention, the fuel gas is methane. When the oxidant is oxygen, the volume flow ratio of methane to oxygen is controlled between 1.05:2 and 20:1. When the oxidant is air, its flow rate is converted into an equivalent oxygen flow rate based on an oxygen content of 21%.
[0019] In a preferred embodiment of the present invention, when the fuel gas is acetylene and the oxidant is oxygen, the volumetric flow rate ratio of acetylene to oxygen is controlled between 2.05:5 and 20:1; when the oxidant is air, its flow rate is converted into an equivalent oxygen flow rate based on an oxygen content of 21%.
[0020] In a preferred embodiment of the present invention, when the fuel gas is hydrogen and the oxidant is oxygen, the volume flow ratio of hydrogen to oxygen is controlled between 2.05:1 and 10:1; when the oxidant is air, its flow rate is converted into an equivalent oxygen flow rate based on an oxygen content of 21%.
[0021] Controlling the volumetric flow rate ratio of fuel gas and oxidant is crucial to achieving the core objective of generating oxides with oxygen vacancies rather than their fully oxidized state or metallic elements under high-temperature combustion. This ensures precise control of the reducing atmosphere, providing a reliable and repeatable process for obtaining highly active and stable catalysts.
[0022] In a preferred embodiment of the present invention, in step (3), the iridium-containing compound is chloroiridium acid, and the ruthenium-containing compound is ruthenium trichloride; the solution is an aqueous solution, an ethanol solution, or an isopropanol solution; and the spraying method is selected from one of pressure spraying, airflow spraying, electrostatic spraying, rotating disk spraying, or ultrasonic spraying.
[0023] Another technical solution adopted by the present invention is: providing a water electrolysis hydrogen production membrane electrode, comprising a proton exchange membrane, an anode catalyst layer coated on one side of the proton exchange membrane, a cathode catalyst layer coated on the other side of the proton exchange membrane, and gas diffusion layers respectively disposed on the outer surfaces of the anode and cathode catalyst layers, wherein the anode catalyst layer comprises a water electrolysis catalyst as described in any one of claims 1 to 4; the cathode catalyst layer comprises a platinum-based catalyst; and in the anode catalyst layer, the total loading of iridium and ruthenium is 0.1 mg / cm² to 2.0 mg / cm², preferably 0.5 mg / cm². 2The preferred Pt loading in the cathode catalyst layer is 0.5 mg / cm³. 2 The gas diffusion layers for the anode and cathode are titanium felt and carbon paper, respectively.
[0024] The beneficial effects of the present invention are: the water electrolysis catalyst and its preparation method provided by the present invention, through a unique flame spray combustion process, prepare a substoichiometric metal oxide with a stable lattice structure and abundant oxygen vacancies.
[0025] A stable crystal structure can effectively resist the erosion of the harsh environment of the anode, avoiding the dissolution and loss of active components, thus ensuring the ultra-high stability of the catalyst during long-term operation. The abundant oxygen vacancies inherent in the crystal structure not only provide a large number of highly active sites and significantly reduce the overpotential of the oxygen evolution reaction, but also greatly improve the electronic conductivity of the material, thereby effectively reducing the ohmic resistance of the electrolyzer and improving the energy conversion efficiency. The uniform particle size at the nanoscale endows a huge specific surface area, allowing the active sites to be fully exposed, further enhancing the catalytic efficiency.
[0026] The preparation process of this invention is simple, reproducible, efficient, environmentally friendly, and produces high-quality products that are easy to scale up for production.
[0027] The water electrolysis membrane electrode using the catalyst of this invention achieves a perfect combination of high-efficiency hydrogen production and ultra-long operating life, with overall performance far exceeding that of catalysts prepared by traditional methods. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:
[0029] Figure 1 This is a schematic diagram of the process flow for synthesizing a hydrogen production catalyst by water electrolysis using the flame spray combustion method according to the present invention. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0032] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0033] In the description of this invention, it should be noted that the terms "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is conventionally placed during use. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0034] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0035] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0036] like Figure 1 As shown, fuel gas and oxidant are introduced into the flame burner, and the precursor solution is introduced into the combustion chamber by spraying to carry out the combustion reaction, and successively undergoes the particle nucleus formation and particle growth process to generate the target catalyst particles in one step.
[0037] This invention includes:
[0038] Example 1: A method for preparing an electrolyzed water catalyst, the specific steps are as follows:
[0039] Introduce methane and oxygen into a flame burner, ignite and burn. Control the methane flow rate at 1.05 L / min and the oxygen flow rate at 2.0 L / min (the volume flow ratio of methane to oxygen is 1.05:2). Subsequently, by means of pressure spraying, spray an aqueous solution of 0.1 mol / L of iridium chloride (H2IrCl6) into the combustion chamber at a rate of 5 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0040] After characterization, this powder is iridium oxide (IrOx) nanoparticles, where 0 < x < 2, the average particle size is about 3 nanometers, and it has a stable lattice structure.
[0041] Example 2: A method for preparing an electrolyzed water catalyst, the specific steps are as follows:
[0042] Introduce acetylene and oxygen into a flame burner, ignite and burn. Control the acetylene flow rate at 5.0 L / min and the oxygen flow rate at 1.0 L / min (the volume flow ratio of acetylene to oxygen is 5:1). Subsequently, by means of gas flow spraying, spray an aqueous solution of 0.2 mol / L of ruthenium chloride (RuCl3) into the combustion chamber at a rate of 3 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0043] After characterization, this powder is ruthenium oxide (RuOx) nanoparticles, where 0 < x < 2, the average particle size is about 4 nanometers, and it has a stable lattice structure.
[0044] Example 3: A method for preparing an electrolyzed water catalyst, the specific steps are as follows:
[0045] Introduce hydrogen and oxygen into a flame burner, ignite and burn. Control the hydrogen flow rate at 2.05 L / min and the oxygen flow rate at 1.0 L / min (the volume flow ratio of hydrogen to oxygen is 2.05:1). Subsequently, by means of ultrasonic spraying, spray a mixed aqueous solution containing 0.1 mol / L of iridium chloride (H2IrCl6) and 0.1 mol / L of ruthenium chloride (RuCl3) into the combustion chamber at a rate of 10 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0046] After characterization, this powder is a nanocomposite of iridium oxide (IrOx) and ruthenium oxide (RuOx), where 0 < x < 2, the average particle size is about 5 nanometers, and it has a stable lattice structure.
[0047] Example 4: A method for preparing an electrolyzed water catalyst, the specific steps are as follows:
[0048] Introduce methane and air into the flame burner and ignite them. Control the methane flow rate at 1.05 L / min and the air flow rate at 10 L / min (converted according to the oxygen content of 21% in air, the equivalent oxygen flow rate is 2.1 L / min, and the volume flow ratio of methane to equivalent oxygen is 1:2). Subsequently, by means of pressure spraying, a mixed ethanol solution containing 0.1 mol / L of iridium chlorate (H2IrCl6) and 0.4 mol / L of titanium isopropoxide (Ti(OCH(CH3)2)4) is sprayed into the combustion chamber at a rate of 5 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0049] Characterization shows that this powder is a nano - composite of iridium oxide (IrOx) and titanium oxide (TiOx), where 0 < x < 2, the average particle size is about 5 nanometers, and TiOx highly disperses the IrOx active component as a conductive carrier.
[0050] Example 5: A preparation method of an electrolytic water catalyst, the specific steps are as follows:
[0051] Introduce acetylene and air into the flame burner and ignite them. Control the acetylene flow rate at 3.0 L / min and the air flow rate at 25 L / min (the equivalent oxygen flow rate is 5.25 L / min, and the volume flow ratio of acetylene to equivalent oxygen is approximately 3:5.25). Subsequently, by means of gas - flow spraying, a mixed aqueous solution containing 0.1 mol / L of iridium chlorate (H2IrCl6) and 0.6 mol / L of manganese chloride (MnCl2) is sprayed into the combustion chamber at a rate of 3 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0052] Characterization shows that this powder is a nano - composite of iridium oxide (IrOx) and manganese oxide (MnOx), where 0 < x < 2, the average particle size is about 6 nanometers, and MnOx highly disperses the IrOx active component as a conductive carrier.
[0053] Example 6: A preparation method of an electrolytic water catalyst, the specific steps are as follows:
[0054] Introduce hydrogen and air into the flame burner and ignite them. Control the hydrogen flow rate at 2.5 L / min and the air flow rate at 5.0 L / min (the equivalent oxygen flow rate is 1.05 L / min, and the volume flow ratio of hydrogen to equivalent oxygen is approximately 2.38:1). Subsequently, by means of rotating disk spraying, a mixed ethanol solution containing 0.1 mol / L of ruthenium trichloride (RuCl3) and 0.8 mol / L of zirconium n - butoxide (Zr(OC4H9)4) is sprayed into the combustion chamber at a rate of 6 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0055] Characterization shows that the powder is a nanocomposite of ruthenium oxide (RuOx) and zirconium oxide (ZrOx), where 0 < x < 2, the average particle size is about 5 nm, and ZrOx highly disperses the RuOx active component as a conductive carrier.
[0056] Example 7: A method for preparing an electrolytic water catalyst, the specific steps are as follows:
[0057] Inject methane and oxygen into a flame burner, ignite and burn. Control the methane flow rate at 2.0 L / min and the oxygen flow rate at 2.0 L / min (the volume flow ratio of methane to oxygen is 1:1). Subsequently, by means of electrostatic spraying, a mixed aqueous solution containing 0.1 mol / L ruthenium trichloride (RuCl3) and 1.0 mol / L cerium nitrate (Ce(NO3)3) is sprayed into the combustion chamber at a rate of 10 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0058] Characterization shows that the powder is a nanocomposite of ruthenium oxide (RuOx) and cerium oxide (CeOx), where 0 < x < 2, the average particle size is about 8 nm, and CeOx highly disperses the RuOx active component as a conductive carrier.
[0059] Example 8: A method for preparing an electrolytic water catalyst, the specific steps are as follows:
[0060] Inject acetylene and oxygen into a flame burner, ignite and burn. Control the acetylene flow rate at 4.0 L / min and the oxygen flow rate at 5.0 L / min (the volume flow ratio of acetylene to oxygen is 4:5). Subsequently, by means of pressure spraying, a mixed ethanol solution containing 0.1 mol / L hydrogen hexachloroiridate (H2IrCl6), 0.2 mol / L ruthenium trichloride (RuCl3), 0.2 mol / L titanium isopropoxide (Ti(OCH(CH3)2)4) and 0.2 mol / L cerium nitrate (Ce(NO3)3) is sprayed into the combustion chamber at a rate of 5 mL / min for reaction. Collect the reaction product to obtain a black powder.
[0061] Characterization shows that the powder is a nanocomposite of iridium oxide (IrOx), ruthenium oxide (RuOx), titanium oxide (TiOx) and cerium oxide (CeOx), where 0 < x < 2, the average particle size is about 8 nm, and the combined action of multiple carriers realizes the efficient dispersion of the active components.
[0062] Comparative Example 1: A method for preparing a comparative catalyst, the specific steps are as follows:
[0063] Methane and oxygen were introduced into the flame burner and ignited. The methane flow rate was controlled at 25 L / min and the oxygen flow rate at 1.0 L / min (the volumetric flow ratio of methane to oxygen was 25:1, far exceeding the upper limit required by this invention). Subsequently, a 0.1 mol / L aqueous solution of chloroiridium acid (H₂IrCl₆) was sprayed into the combustion chamber at a rate of 5 mL / min using a pressure spray method to carry out the reaction. The reaction products were collected to obtain a black powder.
[0064] Characterization revealed that due to the excessive amount of methane and the strong reducing atmosphere, the product was a complex of metallic iridium (Ir) and iridium oxide (IrOx) (Ir / IrOx), with an average particle size of approximately 3 nanometers.
[0065] Comparative Example 2: A method for preparing a comparative catalyst, the specific steps of which are as follows:
[0066] Acetylene and oxygen were introduced into the flame burner and ignited. The acetylene flow rate was controlled at 30 L / min and the oxygen flow rate at 1.0 L / min (the volumetric flow ratio of acetylene to oxygen was 30:1, far exceeding the upper limit required by this invention). Subsequently, a 0.2 mol / L ruthenium trichloride (RuCl3) aqueous solution was sprayed into the combustion chamber at a rate of 3 mL / min via a jet spray to carry out the reaction. The reaction products were collected to obtain a black powder.
[0067] Characterization revealed that due to the excessive acetylene and the strong reducing atmosphere, the product was a complex of ruthenium (Ru) and ruthenium oxide (RuOx) (Ru / RuOx), with an average particle size of approximately 4 nanometers.
[0068] Comparative Example 3: A method for preparing a comparative catalyst, the specific steps of which are as follows:
[0069] Methane and oxygen were introduced into a flame burner and ignited. The methane flow rate was controlled at 0.5 L / min and the oxygen flow rate at 2.0 L / min (the volumetric flow ratio of methane to oxygen was 0.5:2, or 0.25:1, far below the lower limit required by this invention). Subsequently, a 0.1 mol / L aqueous solution of chloroiridium acid (H₂IrCl₆) was sprayed into the combustion chamber at a rate of 5 mL / min using a pressure spray method to carry out the reaction. The reaction products were collected to obtain a black powder.
[0070] Characterization revealed that due to excess oxygen and a strong oxidizing atmosphere, the product was completely oxidized to stoichiometric iridium dioxide (IrO2) with an average particle size of approximately 3 nanometers.
[0071] Comparative Example 4: A method for preparing a comparative catalyst, the specific steps of which are as follows:
[0072] Acetylene and oxygen are introduced into the flame burner and ignited. The acetylene flow rate is controlled at 2.0 L / min and the oxygen flow rate is 10.0 L / min (the volume flow ratio of acetylene to oxygen is 2:10, that is, 0.2:1, far lower than the lower limit required by the present invention). Subsequently, an aqueous solution of ruthenium trichloride (RuCl3) with a concentration of 0.2 mol / L is sprayed into the combustion chamber at a rate of 3 mL / min by means of gas flow spraying for reaction. The reaction products are collected to obtain black powder.
[0073] After characterization, due to the excess oxygen and in a strong oxidizing atmosphere, the product is completely oxidized to ruthenium dioxide (RuO2) with a stoichiometric ratio, and the average particle size is about 4 nanometers.
[0074] The catalyst powders prepared in the above examples and comparative examples were subjected to physical and chemical characterization. The results showed that:
[0075] The catalysts successfully prepared in Examples 1-8 of the present invention have their main active components existing in the form of iridium oxide (IrOx) and / or ruthenium oxide (RuOx), and are all in a sub-stoichiometric ratio state of 0 < x < 2. When auxiliary components are added, the carriers exist in the form of titanium oxide (TiOx), cerium oxide (CeOx), manganese oxide (MnOx), and zirconium oxide (ZrOx), also satisfying 0 < x < 2. All the catalyst products have small particle sizes and uniform distributions, and the average particle sizes are all in the range of 3-8 nanometers, forming a stable lattice structure.
[0076] In contrast, in Comparative Example 1 and Comparative Example 2, due to the excessive volume flow ratio of fuel gas (methane, acetylene) to oxygen, the reducing atmosphere is too strong, resulting in partial over-reduction of IrOx and RuOx to metallic Ir and Ru单质, and the final product is a complex of Ir / IrOx and Ru / RuOx. In Comparative Example 3 and Comparative Example 4, due to the too small volume flow ratio of fuel gas to oxygen and the excess oxygen, in an oxidizing atmosphere, the precursor is completely oxidized, directly generating stoichiometric iridium dioxide (IrO2) and ruthenium dioxide (RuO2).
[0077] The catalyst powders prepared in the above Examples 1-8 and Comparative Examples 1-4 were respectively mixed with an ionic polymer (D520) and a solvent to prepare an electrolytic water anode catalytic layer ink. At the same time, a cathode catalytic layer ink was prepared with a Pt / C catalyst. Using the ultrasonic spraying method, the anode catalytic layer ink and the Pt / C catalytic layer ink were respectively sprayed on both sides of the proton membrane N117 to form thin-layer anode and cathode catalytic layers covering the membrane. The total loading of Ir and Ru in the anode is 0.5 mg / cm 2 , and the Pt loading in the cathode is 0.5 mg / cm 2。The anode and cathode use titanium felt and carbon paper as gas diffusion layers respectively. After the electrolyzed water hydrogen production membrane electrode is assembled into an electrolyzer, electrolyzed water tests are carried out at 60 °C, and the results are shown in the following table:
[0078]
[0079] It can be seen from the data in the above table that: (1) For the electrolyzers assembled in Examples 1, 3, 4, 5, and 8 (mainly containing IrOx), the initial voltages at a current density of 2 A / cm² are all lower than 1.75 V; the electrolyzer voltages of Examples 2, 6, and 7 (only containing RuOx) are also lower than 1.82 V. This shows that the catalyst of the present invention has extremely high electrochemical activity.
[0080] However, the electrolyzer voltages of Comparative Examples 3 and 4 (with compositions of IrO2 and RuO2) are as high as above 1.95 V. This significant performance gap fully proves that: on the one hand, the improvement of the catalyst performance of the present invention stems from the high specific surface area and abundant active sites brought by its nanoscale particle size and uniform structure; on the other hand, more crucially, it stems from the abundant oxygen vacancies introduced by the sub-stoichiometric ratio characteristics (0 < x < 2). These oxygen vacancies greatly improve the intrinsic activity and electron conductivity of the material, thus significantly reducing the ohmic internal resistance.
[0081] (2) During the constant current test lasting up to 2000 hours, the voltage change rates of the catalysts in Examples 1-8 are all very low, remaining below 5 μV / hr, demonstrating excellent durability.
[0082] However, the voltage change rates of Comparative Examples 1 and 2 (containing Ir / IrOx, Ru / RuOx) increase sharply, exceeding 25 μV / hr. This is because the metal elements Ir and Ru contained in them are unstable at high anodic potentials and are easily oxidized into ions and dissolved and lost, resulting in a rapid decay of the active area of the catalyst. This comparison有力地证明,本发明通过精确控制工艺参数所获得的稳定晶格结构的氧化物,能够有效避免此类溶解问题,从而确保了催化剂的长寿命运行。
[0083] In summary, the comparison between the examples and the comparative examples fully verifies the significant progress of the technical solution of the present invention. Precise control of the volume flow ratio of the fuel gas and the oxidant to form a specific weakly reducing atmosphere is the key to preparing a sub-stoichiometric metal oxide catalyst with high activity, low internal resistance, and long life. The present invention not only includes a preparation method with simple process and environmental protection, but also simultaneously realizes a high-activity and excellent-stability electrolyzed water catalyst.
[0084] It should be noted that there is an error in the original Chinese text in line 15. It says "有力地证明" which is in Chinese. It should be something like "This comparison strongly proves" in English. The above translation has made the correction.The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A water electrolysis catalyst, characterized in that, The catalyst contains iridium oxide (IrOx) and / or ruthenium oxide (RuOx), where 0 < x < 2, and the catalyst has a stable lattice structure and a nanoscale particle size.
2. The water electrolysis catalyst according to claim 1, characterized in that, The catalyst also includes a mixture composed of one or more of titanium oxide (TiOx), cerium oxide (CeOx), manganese oxide (MnOx), and zirconium oxide (ZrOx) as a conductive carrier, where 0 < x < 2.
3. The water electrolysis catalyst according to claim 2, characterized in that, The TiOx, CeOx, MnOx, or ZrOx is derived from a titanium-, cerium-, manganese-, or zirconium-containing compound, including one or more of titanium isopropoxide, titanium tetrachloride, cerium nitrate, cerium acetate, cerium chloride, manganese nitrate, manganese tetrachloride, zirconium n-butoxide, or zirconium chloride.
4. The water electrolysis catalyst according to claim 1, characterized in that, The range of x is 0.5 < x < 1.9; the average particle size of the nanoscale particle size is between 3 and 8 nanometers.
5. A method for preparing a water electrolysis catalyst, characterized in that, The method includes the following steps: (1) Introduce fuel gas and an oxidant into a flame burner and ignite for combustion. (2) Control the volume flow ratio of the fuel gas and the oxidant to form a reducing atmosphere in the combustion chamber, which is sufficient to generate an oxide with oxygen vacancies from the metal compound under high-temperature combustion, but not sufficient to reduce it to the elemental metal. (3) Introduce a solution of an iridium-containing or ruthenium-containing compound into the combustion chamber by spraying for a combustion reaction to generate the iridium oxide (IrOx) or ruthenium oxide (RuOx), where 0 < x < 2. (4) Collect the product after the combustion reaction to obtain the electrolytic water catalyst.
6. The method for preparing the water electrolysis catalyst according to claim 5, characterized in that, The fuel gas is methane. When the oxidant is oxygen, the volume flow ratio of methane to oxygen is controlled between 1.05:2 and 20:1; when the oxidant is air, its flow rate is converted to an equivalent oxygen flow rate according to the oxygen content of 21%.
7. The method for preparing the water electrolysis catalyst according to claim 5, characterized in that, The fuel gas is acetylene. When the oxidant is oxygen, the volume flow ratio of acetylene to oxygen is controlled between 2.05:5 and 20:1; when the oxidant is air, its flow rate is converted to an equivalent oxygen flow rate according to the oxygen content of 21%.
8. The method for preparing the water electrolysis catalyst according to claim 5, characterized in that, The fuel gas is hydrogen. When the oxidant is oxygen, the volume flow ratio of hydrogen to oxygen is controlled between 2.05:1 and 10:1; when the oxidant is air, its flow rate is converted to an equivalent oxygen flow rate according to the oxygen content of 21%.
9. The method for preparing the water electrolysis catalyst according to claim 5, characterized in that, In step (3), the iridium-containing compound is chloroiridic acid, and the ruthenium-containing compound is ruthenium trichloride; the solution is an aqueous solution, an ethanol solution, or an isopropanol solution; the spraying method is selected from one of pressure spraying, gas flow spraying, electrostatic spraying, rotating disk spraying, or ultrasonic spraying.
10. A membrane electrode for hydrogen production by water electrolysis, comprising a proton exchange membrane, an anode catalyst layer coated on one side of the proton exchange membrane, a cathode catalyst layer coated on the other side of the proton exchange membrane, and gas diffusion layers respectively disposed on the outer surfaces of the anode and cathode catalyst layers, characterized in that, The anode catalyst layer comprises an electrolytic water catalyst as described in any one of claims 1 to 4; the cathode catalyst layer comprises a platinum-based catalyst; and the total loading of iridium and ruthenium in the anode catalyst layer is 0.1 mg / cm³. 2 Up to 2.0 mg / cm 2 .