Cobaltosic oxide loaded nanoscale amorphous iridium oxide electrolyzed water catalytic material and preparation method thereof

Abstract

The invention belongs to but not limited to the technical field of synthesis of inorganic materials, and discloses a cobaltosic oxide loaded nanoscale amorphous iridium oxide water electrolysis catalytic material and a preparation method thereof. The preparation method comprises the following steps: preparing a mixed solution of CoCl2. 6H2O, IrOx.xH2O and NaNO3; performing ultrasonic treatment and magnetic stirring on the mixed solution; drying in a drying oven at a specific temperature to obtain solid powder; carrying out calcination treatment on the solid powder in an air atmosphere, naturally cooling to room temperature, and reacting CoCl2. 6H2O and IrOx.xH2O with NaNO3 at a high temperature to generate a loaded nanoscale catalytic active component; and centrifugally collecting the obtained product, washing with ultrapure water and ethanol for multiple times, and drying to obtain the nanoscale loaded IrOx / Co3O4 catalyst. According to the prepared catalytic material, the loading capacity of Ir is reduced, and the catalytic performance and stability of the IrOx electrolysis water oxygen evolution reaction are improved.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of inorganic material synthesis technology, and particularly relates to a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material and its preparation method. Background Technology

[0002] Among various technologies for producing hydrogen fuel, water electrolysis, which converts electricity into hydrogen and avoids the emission of harmful gases, is one of the most promising energy conversion technologies. However, the sluggish kinetics of the oxygen evolution reaction (OER) has become a bottleneck for this technology, limiting its development. Furthermore, the high loading of precious metals, which are crucial for efficient water electrolysis in acidic environments, poses a significant challenge to the large-scale use of catalysts. Transition metal oxides are potential alternatives to precious metal-based water electrolysis catalysts, and introducing them is a unique approach to improving the catalytic activity of iridium oxide OER catalysts.

[0003] Based on the above analysis, the urgent technical problems that need to be solved in the existing technology are: first, the slow kinetics of the oxygen evolution reaction (OER) restricts the overall development of the technology; second, the high loading of noble metal catalysts in acidic environments restricts large-scale application; and third, the application of transition metal oxide substitutes is immature and has failed to effectively overcome the first two major bottlenecks. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material and its preparation method, thereby solving the problems of high iridium loading, high cost, low reactivity, and poor stability in existing water electrolysis catalytic materials.

[0005] This invention is achieved by providing a method for preparing a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst, comprising the following steps: Step 1, prepare CoCl2·6H2O and IrO x A mixed solution of xH2O and NaNO3.

[0006] Step 2: Sonicate the mixed solution and stir it magnetically.

[0007] Step 3: Dry in an oven at a specific temperature to obtain a solid powder.

[0008] Step 4: The solid powder is calcined in air at a set temperature for a set time, then naturally cooled to room temperature. CoCl₂·6H₂O and IrO are then reacted at the high temperature. x xH2O reacts with NaNO3 to generate supported nanoscale catalytically active components.

[0009] Step 5: Collect the obtained product by centrifugation, wash it multiple times with ultrapure water and ethanol, and dry it to obtain nanoscale supported IrO. x / Co3O4 catalyst.

[0010] Furthermore, in step 1, CoCl2·6H2O and IrO x The mass ratio of xH2O and NaNO3 in the synthesis is 18:x:80; where IrO x The mass ratio of x in the synthesis of xH2O is 1≤x≤8.

[0011] Furthermore, in step 3, the duration of continuous ultrasound is 30 min-60 min.

[0012] Furthermore, in step 3, the stirring time is 30 min-60 min.

[0013] Furthermore, in step 3, the set temperature for heating the oven is 100℃~120℃, and the set duration is 24h.

[0014] Furthermore, in step 4, the material is calcined in air at a temperature of 350℃ to 550℃, at a rate of 5℃ / min, for a heating time of 1h to 2h.

[0015] Furthermore, in step 5, the washing process involves centrifuging the solid powder catalyst material 3 to 6 times with deionized water and ethanol.

[0016] Another objective of this invention is to provide a cobalt tetroxide-supported nanoscale amorphous iridium oxide water electrolysis catalyst, composed of IrO x It is composed of Co3O4.

[0017] Another objective of this invention is to provide an application of a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalyst in water electrolysis for oxygen production.

[0018] Another objective of this invention is to provide an application of a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalyst in proton exchange membrane water electrolysis for oxygen production.

[0019] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows: For IrO x To address the problems associated with Co3O4, this invention uses IrO x Loading onto Co3O4 to form surface-loaded nanoscale amorphous IrO x / Co3O4 catalyst material reduces the Ir loading while increasing the IrO content. xThe catalytic performance and stability of the oxygen evolution reaction in water electrolysis were studied, leading to the development of new catalytic materials for efficient oxygen production in proton exchange membrane water electrolysis equipment, specifically targeting IrO. x The practical application of both Co3O4 and Co3O4 in the field of water electrolysis catalysis is of great significance.

[0020] The preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalyst provided by this invention is simple and has a short experimental cycle. The cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalyst prepared by this invention can be used for oxygen production through water electrolysis and proton exchange membrane water electrolysis.

[0021] The expected benefits and commercial value of the technical solution after transformation are as follows: The cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material prepared by this invention can be used for oxygen production through water electrolysis and proton exchange membrane water electrolysis. In addition to its excellent kinetic properties, the cobalt tetroxide-supported nanoscale amorphous iridium oxide structure, as a catalyst layer, exhibits superior electron and mass transport capabilities in practical PEMWE, at 1 A cm⁻¹. -2 At the operating current, its corresponding overpotential is 600 mV lower than that of commercial IrO2. It is noteworthy that this is achieved using a loading of only 0.35 mgIr cm⁻¹. -2 PEMWE using cobalt tetroxide-supported nanoscale amorphous iridium oxide anode catalyst can achieve 4 A cm⁻¹ at 1.99 V. -2 High operating current, and can operate at currents above 0.5 A cm⁻¹. -2 It operates stably for 450 hours at industrial-grade current density, and its overall performance ranks among the top of reported low-iridium-load electrolyzers. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water catalytic material provided in this embodiment of the invention.

[0023] Figure 2 This is a scanning electron microscope (SEM) image of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water catalyst provided in Example 1 of the present invention.

[0024] Figure 3 This is a transmission electron microscope (TEM) image and composition distribution diagram of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water catalyst material provided in Example 1 of the present invention.

[0025] Figure 4 This is a transmission electron microscope (TEM) image of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water catalyst material provided in Example 1 of the present invention.

[0026] Figure 5This is a schematic diagram of the water electrolysis oxygen production performance of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material provided in Example 1 of the present invention.

[0027] Figure 6 This is a schematic diagram of the proton exchange membrane oxygen production performance of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material provided in Embodiment 1 of the present invention.

[0028] Figure 7 This is a stability test of water-based oxygen production and proton exchange membrane electrolysis for oxygen production, according to an embodiment of the present invention.

[0029] Figure 8 The present invention relates to a cobalt-supported nanoscale amorphous iridium oxide electrolytic water catalytic material membrane.

[0030] Figure 9 This invention relates to a device using a cobalt oxide-supported nanoscale amorphous iridium oxide electrolytic water-splitting catalyst. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] like Figure 1 As shown, this embodiment of the invention provides a method for preparing a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst, comprising the following steps: Step 1, prepare CoCl2·6H2O and IrO x A mixed solution of xH2O and NaNO3.

[0033] Step 2: Sonicate the mixed solution and stir it magnetically.

[0034] Step 3: Dry in an oven at a specific temperature to obtain a solid powder.

[0035] Step 4: The solid powder is calcined in air at a set temperature for a set time, then naturally cooled to room temperature. CoCl₂·6H₂O and IrO are then reacted at the high temperature. x xH2O reacts with NaNO3 to generate supported nanoscale catalytically active components.

[0036] Step 5: Collect the obtained product by centrifugation, wash it multiple times with ultrapure water and ethanol, and dry it to obtain nanoscale supported IrO. x / Co3O4 catalyst.

[0037] The present invention discloses a method for preparing a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water catalytic material. Its core working principle lies in achieving uniform growth and stable loading of nanoscale amorphous IrOx on the surface of a Co3O4 support through solution precursor regulation, oxidant-assisted reaction, and high-temperature calcination, thereby obtaining an electrolytic water catalytic structure with high activity and high stability.

[0038] In step 1, the homogeneous mixed solution formed by the co-dissolution of CoCl2·6H2O, IrOx·xH2O, and NaNO3 constitutes the chemical precursor system of the catalytic material. CoCl2·6H2O provides divalent cobalt ions, which can be oxidized to form spinel structure Co3O4 through subsequent heat treatment; IrOx·xH2O is an amorphous iridium oxide precursor, which can be further dehydrated, rearranged, or partially oxidized under thermal drive; NaNO3, as an oxidant and dispersion promoter, not only provides an oxidizing atmosphere during heating but also inhibits the rapid aggregation of metal precursors, keeping IrOx in a highly dispersed state during formation.

[0039] The ultrasonic treatment and magnetic stirring in step 2 can effectively promote the Co² + IrOx precursor, NO3 - The plasma or colloidal particles are thoroughly mixed to generate a stable precursor complex structure. Ultrasonic cavitation breaks down micro-aggregates, improving the dispersibility of IrOx·xH2O in solution and ensuring that the subsequently formed amorphous IrOx can uniformly adhere to the surface of the Co3O4 support. Furthermore, the stirring process promotes short-range migration of ion exchange and redox reactions, laying the foundation for the formation of highly uniform composite materials.

[0040] Step 3, the drying process, evaporates the solvent, causing the mixed components to shrink and form a solid powder. During this stage, a preliminary contact interface forms between the IrOx precursor and the cobalt salt precursor, and some NO3-... - It may begin to participate in low-temperature decomposition, providing activation sites for subsequent high-temperature reactions.

[0041] In step 4, the high-temperature calcination in air is a crucial step in regulating the structure of the catalytic material. As the temperature rises, CoCl2·6H2O dehydrates and gradually oxidizes, eventually transforming into Co3O4 with a spinel structure. NaNO3 decomposes at high temperature to produce active oxygen species such as NO2 and O2, which can promote further oxidation and amorphous structure solidification of IrOx·xH2O, resulting in IrOx exhibiting a nanoscale, short-range ordered but lacking long-range lattice arrangement amorphous morphology. Simultaneously, the Co3O4 surface possesses abundant hydroxyl groups, oxygen vacancies, and lattice discontinuities, which can strongly interact with amorphous IrOx (including electrostatic adsorption, surface coordination, and strong interaction loading (SMSI) effects), thereby enabling IrOx to nucleate and grow in situ on the support surface and exhibit a uniform nanoscale distribution.

[0042] Step 5 involves centrifugation, washing, and drying to remove residual impurities, resulting in a final IrOx / Co3O4 composite catalyst with a pure interface and stable configuration. Amorphous IrOx, due to its random structure, abundant low-coordination sites, and high oxygen defect concentration, is more likely to provide high-valence iridium active centers for the OER reaction from an electronic structure perspective. Meanwhile, the Co3O4 support can enhance overall catalytic activity and durability through synergistic charge regulation, electron supply, and interface stabilization.

[0043] Therefore, the preparation method of the present invention achieves nano-amorphous loading of IrOx through solution homogenization, oxidant assistance and high-temperature solid-phase reaction, effectively constructing a highly active interface structure, thereby significantly improving the catalytic performance and structural stability of the oxygen evolution reaction in water electrolysis.

[0044] Furthermore, in step 1, CoCl2·6H2O and IrO x ·xH2O, NaNO3, where IrO x The mass ratio of x in the synthesis of xH2O is 1≤x≤8.

[0045] Furthermore, in step 3, the duration of continuous ultrasound is 30 min-60 min.

[0046] Furthermore, in step 3, the stirring time is 30 min-60 min.

[0047] Furthermore, in step 3, the set temperature for heating the oven is 100℃~120℃, and the set duration is 24h.

[0048] Furthermore, in step 4, the material is calcined in air at a temperature of 350℃ to 550℃, at a rate of 5℃ / min, for a heating time of 1h to 2h.

[0049] Furthermore, in step 5, the washing process involves centrifuging the solid powder catalyst material 3 to 6 times with deionized water and ethanol.

[0050] Configure CoCl2·6H2O, IrO x A mixed solution of xH2O and NaNO3 was synthesized at a mass ratio of 18:1:80. The mixed solution was ultrasonically treated for 30 min, magnetically stirred for 30 min, and dried in an oven at 120℃ to obtain a solid powder. This solid powder was calcined in air by heating at 550℃ for 1 h, followed by natural cooling to room temperature. The mixture of CoCl2·6H2O and IrO was then subjected to high-temperature calcination. xxH2O reacts with NaNO3 to generate a supported nanoscale catalytically active component. The product is collected by centrifugation, washed six times with ultrapure water and ethanol, and dried to obtain nanoscale supported IrO. x / Co3O4 catalyst.

[0051] Figure 2 The morphology of a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material is shown. Cobalt tetroxide is used as a support surface to support nanoscale amorphous iridium oxide with a size of approximately 200 nm.

[0052] Figure 3 Transmission electron microscopy (TEM) images reveal a rough surface structure of the nanoscale amorphous iridium oxide electrolysis catalyst supported on cobalt tetroxide. Energy dispersive spectroscopy (EDS) results show that the corresponding iridium oxide coexists and is uniformly distributed within the cobalt tetroxide support.

[0053] Figure 4 Transmission electron microscopy images show the structure of nanoscale amorphous iridium oxide on the surface of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis water catalyst, which is uniformly distributed on the cobalt tetroxide support.

[0054] like Figure 5 As shown, the sample of nanoscale amorphous iridium oxide electrolytic water electrolysis catalyst supported on cobalt tetroxide under the conditions of x=3, drying at 100℃ and calcination at 350℃ exhibits a significant improvement in electrocatalytic oxygen production performance. Figure 5 The electrocatalytic oxygen production activity of a cobalt tetroxide-supported nanoscale amorphous iridium oxide water electrolysis catalyst was demonstrated in acidic medium (0.5 M H₂SO₄ aqueous solution). The oxygen production current density of this electrode was 10 mA / cm². -2 The overpotential is much smaller than that of IrO2, indicating that the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water electrolysis catalyst has excellent electrocatalytic oxygen production performance.

[0055] Figure 6 This is a schematic diagram of the oxygen production performance of a proton exchange membrane water electrolysis device using cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalyst provided in an embodiment of the present invention. The electrochemical test curve in pure water shows that, under these conditions, the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalyst achieves an oxygen production rate of 1 A cm⁻¹. 2 With 4 A cm 2 At current densities of only 1.69 V and 1.99 V, respectively, overpotentials are required, compared to IrO2, 1 A cm⁻¹ 2 The overpotential decreased by 600 mV, indicating that the electrode has good electrocatalytic oxygen production performance in the proton exchange membrane water electrolysis equipment.

[0056] The cobalt tetroxide-supported nanoscale amorphous iridium oxide catalytic material prepared in this invention can be used for oxygen production via water electrolysis and proton exchange membrane water electrolysis. In addition to its excellent kinetic properties, the cobalt tetroxide-supported nanoscale amorphous iridium oxide structure, as a catalyst layer, exhibits superior electron and mass transport capabilities in practical PEMWE, at 1 A cm⁻¹. -2 At the operating current, its corresponding overpotential is 600 mV lower than that of commercial IrO2. It is noteworthy that this is achieved using an IrO2 loading of only 0.35 mg / cm³. -2 PEMWE using cobalt tetroxide-supported nanoscale amorphous iridium oxide anode catalyst can achieve 4 A cm⁻¹ at 1.99 V. -2 High operating current, and can operate at currents above 0.5 A cm⁻¹. -2 It operates stably for 450 hours at industrial-grade current density, and its overall performance ranks among the top of reported low-iridium-load electrolyzers.

[0057] The cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material provided by this invention has both high activity and long-term stability, and its application effect in proton exchange membrane electrolysis water production hydrogen and oxygen production system is good. Figure 7 The long-term stability test results of the membrane electrode constructed from the material at different current densities are presented. During the test, the catalytic material was assembled with a Nafion 115 proton exchange membrane to form a membrane electrode assembly with an effective area of ​​2 cm², and the results were obtained at 60 °C and 0.5–4 A·cm². - It can operate continuously for over 450 hours within a current density range of 2. As can be seen from the battery voltage versus time curve in the figure, at 0.5 A·cm²... - Under these conditions, the voltage remains relatively stable at around 1.60V; when the current density increases to 1A·cm²... - ² and 2A·cm - At 2°C, the voltage remained stable in the range of 1.70–1.80V; further at 3A·cm - ² and 4A·cm - Under continuous operation under these conditions, the voltage remained stable without significant decay or voltage spikes. This result demonstrates that the catalyst of this invention maintains rapid reaction kinetics, low overpotential, and excellent structural stability even at high current densities, meeting the requirements of industrial-grade proton exchange membrane water electrolysis devices for continuous operation under high loads.

[0058] Figure 8The microstructure of the catalyst film observed by scanning electron microscopy (SEM) is shown. The cobalt tetroxide support exhibits a sheet-like or blocky structure, with a dense overall structure and certain wrinkled texture. Amorphous iridium oxide is uniformly loaded on its surface without obvious agglomeration, indicating that the loading method used in this invention can achieve stable attachment of the active phase at the nanoscale. The sheet-like support structure provides excellent electron transport channels, while the disordered structure of the amorphous iridium oxide further increases the reactive sites, forming a highly efficient synergistic catalytic interface. The overall film layer is continuous and dense, without obvious pores or peeling areas, proving that the catalytic material has a robust structure and can withstand high current impacts and long-term electrochemical corrosion environments.

[0059] Figure 9 This is a photograph of an actual water electrolysis reactor constructed based on the catalytic membrane of this invention. The reactor employs a metal bipolar plate, sealing gaskets, and a multi-bolt fixing structure. The central area serves as the effective reaction window, with the catalytic membrane and proton exchange membrane tightly bonded and clamped inside the reaction chamber. The device is equipped with water inlet and oxygen outlet channels, enabling stable liquid supply under constant pressure water replenishment conditions, ensuring a wetted reaction interface and maintaining good ion conduction. The upper connection can be connected to a constant current source to achieve continuous operation at high current density. The structure in the figure shows that the catalytic membrane can be stably installed in a real electrolyzer, and no membrane desorption or interfacial short circuit occurred after several hours of operation, further demonstrating its good mechanical stability and engineering adaptability.

[0060] comprehensive Figure 7 – Figure 9 It is evident that the cobalt tetroxide-supported nanoscale amorphous iridium oxide catalyst prepared in this invention not only achieves high dispersion and structural stability in its microstructure, but also exhibits long-term stable operation under high current density in a real proton exchange membrane water electrolysis reactor. Its low voltage plateau and long lifetime characteristics mean that it can significantly reduce the energy consumption cost of hydrogen production through water electrolysis, and has broad application prospects in large-scale electrochemical water cracking, renewable energy hydrogen production, and other fields.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst, characterized in that, Includes the following steps: Step 1, prepare CoCl2·6H2O and IrO x A mixed solution of xH2O and NaNO3; Step 2: Sonicate the mixed solution and stir it magnetically; Step 3: Dry in an oven at a specific temperature to obtain a solid powder; Step 4: The solid powder is calcined in air at a set temperature for a set time, then naturally cooled to room temperature. CoCl₂·6H₂O and IrO are then reacted at the high temperature. x xH2O reacts with NaNO3 to generate supported nanoscale catalytically active components; Step 5: Collect the obtained product by centrifugation, wash it multiple times with ultrapure water and ethanol, and dry it to obtain nanoscale supported IrO. x / Co3O4 catalyst.

2. The preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst as described in claim 1, characterized in that, In step 1, CoCl2·6H2O and IrO x The mass ratio of xH2O and NaNO3 in the synthesis is 18:x:80; where IrO x The mass ratio of x in the synthesis of xH2O is 1≤x≤8.

3. The preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst as described in claim 1, characterized in that, In step 3, the duration of continuous ultrasound is 30 min-60 min.

4. The preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst as described in claim 1, characterized in that, In step 3, the stirring time is 30 min-60 min.

5. The preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst as described in claim 1, characterized in that, In step 3, the set temperature of the oven is 100℃~120℃, and the set duration is 24h.

6. The preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst as described in claim 1, characterized in that, In step 4, the material is calcined in air at a temperature of 350℃ to 550℃, at a rate of 5℃ / min, for a heating time of 1h to 2h.

7. The preparation method of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst as described in claim 1, characterized in that, In step 5, washing involves centrifuging the solid powder catalyst material 3 to 6 times with deionized water and ethanol.

8. A cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolytic water splitting catalyst prepared by the method according to any one of claims 1 to 7, characterized in that, By IrO x It is composed of Co3O4.

9. The application of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalyst as described in claim 8 in water electrolysis for oxygen production.

10. The application of the cobalt tetroxide-supported nanoscale amorphous iridium oxide electrolysis catalytic material as described in claim 8 in proton exchange membrane electrolysis for oxygen production.

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