A method for preparing two-dimensional carbonyl iridium materials and their applications

Abstract

This invention discloses a method for preparing a two-dimensional carbonyl iridium material and its application. The preparation method is as follows: An iridium precursor solution and a solvent containing amides and carboxylic acids are prepared; small molecules with carboxyl functional groups are added to regulate the material structure; and a nano-iridium composite material with a two-dimensional assembly structure is formed under heating conditions. The two-dimensional carbonyl iridium material prepared by this invention has the same structural characteristics as existing materials, but overcomes the shortcomings of current methods that require a reaction at 400℃, resulting in high energy consumption and cost, and are unsuitable for mass production and continuous operation. When this two-dimensional carbonyl iridium nanomaterial is applied to the field of acidic water electrolysis for oxygen evolution, three-electrode testing results show that in perchloric acid solution, the performance is 10 mA / cm². 2 The overpotential required for the current density is only 248mV; as the anode catalyst layer of the membrane electrode in a proton exchange membrane water electrolysis device, 1A / cm 2 It requires only a cell voltage of about 1.65V and exhibits excellent electrolytic catalytic performance.

Description

Technical Field

[0001] This invention belongs to the field of energy catalysis technology, and relates to a two-dimensional carbonyl iridium material with electrocatalytic activity and its preparation method. It also relates to its application as a catalyst in proton exchange membrane water electrolysis for hydrogen production, and has potential application value in other energy development and environmental protection fields. Background Technology

[0002] In proton exchange membrane (PEM) water electrolysis for hydrogen production, the catalyst must be a corrosion-resistant platinum-based precious metal material. Especially since the anodic reaction is acidic and under strong oxidizing conditions, iridium or iridium oxide is typically used, but its limited availability significantly increases the cost of the electrolyzer. Furthermore, in current technologies, the slow kinetics of the anodic oxidation reaction in water electrolysis is a limiting factor affecting electrolysis efficiency and energy consumption. Therefore, reducing the iridium loading at the anode and improving its catalytic activity are crucial for achieving efficient proton exchange membrane water electrolysis for hydrogen production.

[0003] To address this technical challenge, current industrial processes employ nanoscale iridium or iridium oxide powders to enhance catalytic activity and material utilization, thereby maximizing the use of precious metals. Preparation methods include Adams fusion, colloidal processes, and thermal decomposition, all involving high-temperature reactions such as 400°C. These methods are energy-intensive and costly, and unsuitable for mass production or continuous operation. Furthermore, iridium-based catalysts obtained through existing industrial processes typically exhibit overpotentials exceeding 350 mV in water oxidation reactions, resulting in poor electrolytic catalytic performance and further increasing raw material costs. Summary of the Invention

[0004] This invention addresses the aforementioned problems by providing a method for preparing a two-dimensional carbonyl iridium material and its application in the electrolysis of water to produce hydrogen. In the preparation process of this two-dimensional carbonyl iridium material, a mixture of amide and carboxylic acid is used as a solvent, and small molecules with carboxyl functional groups are added as structure modifiers. Under heating conditions of 80–100°C, a nano-iridium composite material with two-dimensional assembly characteristics can be formed.

[0005] The technical solution of this invention is as follows: An iridium precursor solution and a solvent containing amides and carboxylic acids are prepared; small molecules with carboxyl functional groups are added to regulate the material structure; and a nano-iridium composite material with a two-dimensional assembly structure is formed under heating conditions. Then, structural testing and electrolytic catalytic performance testing are performed. The results show that the two-dimensional carbonyl iridium material prepared by this invention has the same structural characteristics as existing materials, but overcomes the shortcomings of current methods that require reaction at 400℃, resulting in high energy consumption and cost, and are unsuitable for batch and continuous production. Electrolytic catalytic performance testing shows that the two-dimensional carbonyl iridium material of this invention has good electrolytic catalytic performance and structural stability.

[0006] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a two-dimensional carbonyl iridium material, comprising the following steps:

[0008] (1) Dissolve the iridium salt in water to prepare an iridium precursor solution;

[0009] (2) A certain proportion of amide solvent and organic acid solution are mixed to form a reaction medium;

[0010] (3) Add carboxylic acid organic molecules as structure regulators to the mixed medium in step (2);

[0011] (4) After adding the iridium precursor solution from step (1) to the reaction medium from step (3), mix them evenly with the assistance of external force.

[0012] (5) Heat the solution formed in step (4) to 80-100℃, react for 3-10 minutes, cool naturally, and then centrifuge and dry to obtain the two-dimensional carbonyl iridium nanomaterial.

[0013] The preferred process conditions for each of the above steps are as follows:

[0014] In step (1), the concentration of iridium salt in the iridium precursor solution is 5-15 g / L; the iridium salt is selected from any one of iridium chloride, iridium chloroacid, ammonium iridium chloroacid, potassium iridium chloroacid, and sodium iridium chloroacid.

[0015] In step (2), the volume ratio of the amide solvent to the organic acid solution is 1:1; the amide includes, but is not limited to, one or more of dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, and N-methylpyrimidine; the organic acid includes, but is not limited to, one or more of formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malic acid, and tartaric acid.

[0016] In step (3), the final concentration of the added carboxylic acid organic molecules is 0.5 to 1 g / L; the carboxylic acid organic molecules include, but are not limited to, pyromellitic acid, terephthalic acid, and citric acid.

[0017] In step (4), the final concentration of iridium salt is 1.5 to 7 g / L, and the external force assistance is achieved by dissolving through ultrasound or stirring.

[0018] In step (5), the heating methods include microwave heating, oven, water bath, oil bath or heating plate heating; the drying method is vacuum drying at 60℃.

[0019] In a second aspect, this invention provides a two-dimensional carbonyl iridium material, prepared using the method described in any one of the first aspects above. Electron microscopy observations show that the material consists of ultrathin nanosheets assembled into a spherical hierarchical structure, with the nanosheets being atomically thin and the assembled spheres having a size of 200-500 nm.

[0020] In a third aspect, the present invention provides the application of the aforementioned two-dimensional carbonyl iridium material in the preparation of anode catalyst materials for proton exchange membrane water electrolysis to produce hydrogen.

[0021] In a fourth aspect, the present invention provides a proton exchange membrane electrolysis anode for hydrogen production, comprising an anode support and an anode catalyst material supported thereon, wherein the anode catalyst material is the two-dimensional carbonyl iridium material described above.

[0022] In a fifth aspect, this invention provides a method for producing hydrogen through proton exchange membrane electrolysis of water. A membrane electrode is assembled using two-dimensional carbonyl iridium nanomaterials as the anode catalyst and commercial platinum / carbon materials as the cathode catalyst. Hydrogen is produced by electrolysis of water in a proton exchange membrane electrolyzer. Deionized water is pumped into the anode, and oxygen generated after applying voltage to the electrolyzer flows out with the water. Hydrogen is generated at the cathode.

[0023] Preferably, two-dimensional carbonyl iridium nanomaterials are prepared on a proton exchange membrane to form the anode catalyst layer by hot-pressing transfer. This process uses 0.5M HClO4 solution as the electrolyte, and a platinum mesh and an Ag / AgCl electrode as the counter electrode and reference electrode, respectively.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The method for preparing two-dimensional carbonyl iridium nanomaterials of the present invention can be achieved at relatively low temperature conditions (80-100℃), the reaction is rapid and can be completed in a short time, and the reproducibility is high, enabling batch and continuous preparation. At the same time, it overcomes the shortcomings of the current method which requires reaction at 400℃, resulting in high energy consumption and cost, and is not suitable for batch and continuous production.

[0026] (2) The two-dimensional carbonyl iridium nanomaterials were applied to the field of oxygen evolution in acidic water electrolysis. The three-electrode test results showed that in perchloric acid solution, the performance was 10 mA / cm. 2 The overpotential required for the current density is only 248mV. As the anode catalyst layer of the membrane electrode in a proton exchange membrane water electrolysis device, it only requires a cell voltage of about 1.65V per square centimeter for a current density of 1 ampere, demonstrating excellent electrolysis catalytic performance.

[0027] (3) The technology obtains an iridium catalyst with an ultrathin two-dimensional structure, which can improve the utilization rate of the catalyst layer material in the proton exchange membrane water electrolysis device and form a fast electron and mass transport channel in the catalyst layer. Attached Figure Description

[0028] Figure 1 The X-ray diffraction patterns of the two-dimensional carbonyl iridium nanomaterial powders prepared in Examples 1, 2, and 3 are shown.

[0029] Figure 2 Fourier transform infrared spectra of the two-dimensional carbonyl iridium nanomaterials prepared in Examples 1, 2, and 3;

[0030] Figure 3 Scanning electron microscopy image of the two-dimensional carbonyl iridium nanomaterials prepared in Example 1;

[0031] Figure 4 Scanning transmission electron microscopy image of the two-dimensional carbonyl iridium nanomaterials prepared in Example 1;

[0032] Figure 5 These are scanning electron micrographs of the two-dimensional carbonyl iridium nanomaterials prepared in Examples 2 and 3;

[0033] Figure 6 The X-ray absorption fine structure near-edge spectrum and R-space spectrum of the two-dimensional carbonyl iridium nanomaterials prepared in Examples 1, 2 and 3 are shown. Comparative Example 1 is iridium foil and Comparative Example 2 is commercial iridium oxide powder.

[0034] Figure 7 Linear sweep voltammetry curves of the embodiment and comparative materials in the three-electrode test system;

[0035] Figure 8 The bar chart shows the overpotential of the materials in the examples and comparative examples of the three-electrode test system.

[0036] Figure 9 The image shows the current density-voltage curve of the assembled membrane electrode in a proton exchange membrane electrolysis device in Example 1.

[0037] Figure 10 Example 1 shows the proton exchange membrane electrolyzer with a capacity of 1A / cm. 2 Stability test curves at current density. Detailed Implementation

[0038] 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, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The “range” disclosed in this document takes the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this way are inclusive and composable; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 100–140 and 500–900 are listed for a specific parameter, it is also expected that ranges of 100–140 and 500–900 are also included. Furthermore, if the minimum range values ​​are listed as 1 and 2, and if the maximum ranges are listed as 3, 4, and 5, then the following ranges are all expected: 1–2, 1–4, 1–5, 2–3, 2–4, and 2–5.

[0040] In this invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between "0~5" have been listed in this document, and "0~5" is simply an abbreviation of these numerical combinations.

[0041] In this invention, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0042] I. Preparation of Two-Dimensional Carbonyl Iridium Materials

[0043] Example 1

[0044] The preparation method of the two-dimensional carbonyl iridium nanomaterial in this embodiment includes the following steps:

[0045] (1) Dissolve 100 mg of iridium trichloride in 10 mL of deionized water to form a brownish-red transparent precursor solution; then, mix 10 mL each of N,N'-dimethylformamide and formic acid, add 14 mg of trimesic acid, and sonicate to dissolve; mix 7 mL of iridium precursor solution and the mixed N,N'-dimethylformamide and formic acid by sonication until homogeneous.

[0046] (2) Transfer the reaction precursor solution formed in step (1) into a microwave-assisted heating reaction apparatus, microwave heat it to 100°C for about 5 minutes, and then let it cool naturally.

[0047] (3) After centrifuging the substance obtained in step (2), dry it under vacuum at 60°C.

[0048] Example 2

[0049] The operation steps of Example 1 were repeated, except that the amount of pyromellitic acid added was ten times that of Example 1, and the other steps were the same. After drying, the sample of Example 2 was obtained.

[0050] Example 3

[0051] Repeat the steps of Example 1, except that no pyromellitic acid is added. All other steps are the same, and the sample of Example 2 is obtained after drying.

[0052] Comparative Example 1

[0053] Comparative Example 1 is a standard iridium foil sample, used as a metallic comparison sample for X-ray absorption fine spectrum.

[0054] Comparative Example 2

[0055] Comparative Example 2 uses commercially available iridium oxide powder material, which is not purified in any way.

[0056] Comparative Example 3

[0057] Comparative Example 3 uses purchased iridium black powder material without any purification treatment.

[0058] II. Performance Characterization Test

[0059] 1. Feature Detection

[0060] Scanning electron microscope images of the two-dimensional carbonyl iridium materials prepared in Examples 1-3 are shown below. Figure 1 The characteristic diffraction peaks at angles of 7.4°, 37.6° and 67.6° correspond to the (010), (-333) and (656) crystal planes of Ir4(CO)12 crystal;

[0061] The Fourier transform infrared spectra of the two-dimensional carbonyl iridium nanomaterials prepared in Examples 1 to 3 are shown in the figure. Figure 2 It is approximately 2065cm -2 The characteristic peak of the wavenumber is the CO vibration peak.

[0062] 2. Electron microscopy observation

[0063] Figure 3 The image shows a scanning electron microscope image of the two-dimensional carbonyl iridium nanomaterial prepared in Example 1, which shows a spherical structure assembled from wrinkled sheets.

[0064] Figure 4 The image shows a scanning transmission electron microscopy image of the two-dimensional carbonyl iridium nanomaterials prepared in Example 1, which shows that the thickness of the flakes is sub-nanometer and forms a multi-level assembly of ultrathin flake stacks.

[0065] Figure 5 The images shown are scanning electron micrographs of the two-dimensional carbonyl iridium nanomaterials prepared in Examples 2 and 3, demonstrating that the technology of the present invention can prepare materials with similar structures and that the layered microstructure can be controlled.

[0066] 3. Structural Analysis

[0067] Figure 6 The X-ray absorption near-edge spectra and R-space maps of the two-dimensional carbonyl iridium nanomaterials prepared in Examples 1, 2, and 3 are shown. Comparative Example 1 is an iridium foil, and Comparative Example 2 is commercially available iridium oxide powder. The results show that the local structure of the materials in these examples is equivalent to the coordination form of metallic iridium, and the coordination bond length and coordination number are finely regulated with the participation of carboxylic acid molecules.

[0068] 4. Electrolytic catalysis test

[0069] The standard three-electrode test system was used to evaluate the electrocatalytic oxygen evolution reaction activity of the material. The electrolyte was 0.1M HClO4 solution. The sample was drop-coated onto a glassy carbon electrode as the working electrode, and a platinum mesh and an Ag / AgCl electrode were used as the counter electrode and reference electrode, respectively.

[0070] The proton exchange membrane electrolyzer device was tested using a Nafion 115 polyelectrolyte membrane. The sample from Example 1 was used as the anode catalyst, hot-pressed onto the ion exchange membrane to form the catalyst layer. The cathode was assembled using commercially available platinum / carbon materials as the membrane electrode. Deionized water was pumped through the anode using a peristaltic pump, and the corresponding voltage was measured using a constant current electrolysis method.

[0071] Figure 7 The linear sweep voltammetry curves for Example 1 and the comparative materials in the three-electrode test system are shown. The polarization curves of the Example samples show superior catalytic activity compared to commercial iridium black and iridium oxide. The results show that the Example samples have a higher current density at the same potential.

[0072] Figure 8 The bar chart shows the overpotential of the example and comparative materials in the three-electrode test system. The results show that Example 1 has the lowest overpotential, and the overpotentials of the example samples are all significantly lower than those of commercial iridium black and iridium oxide.

[0073] Figure 9 The image shows the current density-voltage curve of the membrane electrode assembled in Example 1 in a proton exchange membrane electrolysis device. As the current density increases, the voltage rises slowly, indicating that this type of material has high catalytic activity in the membrane electrode device.

[0074] Figure 10 Example 1 shows a 1A / cm ratio in a proton exchange membrane electrolysis device. 2 Stability tests under current density conditions showed that the cell voltage remained at 1.65V throughout the 100-hour test period, demonstrating excellent electrolytic catalytic performance.

[0075] In summary, compared with existing methods for preparing catalyst materials in water electrolysis for hydrogen production, this invention has the following advantages: the synthesis process is simple, the conditions are mild, it can be achieved at relatively low temperatures (80–100°C), it has high reproducibility, and it can achieve batch and continuous production. It also overcomes the shortcomings of current methods that require reaction at 400°C, resulting in high energy consumption and cost, and are unsuitable for batch and continuous production.

[0076] This technology yields an iridium catalyst with an ultrathin two-dimensional structure, which can improve the utilization rate of the catalyst layer material in proton exchange membrane water electrolysis devices and form a rapid electron and mass transport channel in the catalyst layer.

[0077] Regarding electrolytic catalytic performance, the two-dimensional carbonyl iridium nanomaterials were applied to the field of acidic water electrolysis for oxygen evolution. Three-electrode testing results showed that in perchloric acid solution, the catalytic performance was 10 mA / cm². 2 The overpotential required for the current density is only 248 mV. As the anode catalyst layer of the membrane electrode in a proton exchange membrane water electrolysis device, 1 A / cm²... 2 It requires only a cell voltage of about 1.65V and exhibits excellent electrolytic catalytic performance.

[0078] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for preparing a two-dimensional carbonyl iridium material, characterized in that, Includes the following steps: (1) Dissolve the iridium salt in water to prepare an iridium precursor solution; (2) A certain proportion of amide solvent and organic acid solution are mixed to form a reaction medium; (3) Add carboxylic acid organic molecules as structure regulators to the reaction medium in step (2); (4) After adding the iridium precursor solution from step (1) to the reaction medium from step (3), mix them evenly with the aid of external force; (5) Heat the solution formed in step (4) to 80-100℃, react for 3-10 minutes, allow it to cool naturally, and then centrifuge and dry to obtain two-dimensional carbonyl iridium nanomaterials. In step (1), the iridium salt is selected from any one of iridium chloride, iridium chloroacid, ammonium iridium chloroacid, potassium iridium chloroacid, and sodium iridium chloroacid; In step (2), the volume ratio of the amide solvent to the organic acid solution is 1:1; In step (3), the final concentration of the added carboxylic acid organic molecules is 0.5 ~ 1 g / L; In step (4), the external force assistance is achieved by ultrasonic or stirring to mix the materials evenly. In step (5), the heating methods include microwave heating, oven drying, water bath, oil bath, or heating plate heating; the drying method is vacuum drying at 60℃. In step (1), the concentration of iridium salt in the iridium precursor solution is 5~15 g / L; In step (2), the amide is selected from one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, and N-methylpyrimidine; the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malic acid, and tartaric acid. In step (3), the carboxylic acid organic molecules include pyromellitic acid, terephthalic acid, and citric acid; In step (4), the final concentration of iridium salt is 1.5~7 g / L.

2. A two-dimensional carbonyl iridium material, characterized in that, It was prepared using the preparation method described in claim 1.

3. The two-dimensional carbonyl iridium material according to claim 2, characterized in that, The material is assembled from ultrathin nanosheets into a spherical multilevel structure. The ultrathin nanosheets are atomically thin, and the morphological size of the spherical multilevel structure is 200-500 nm.

4. The application of the two-dimensional carbonyl iridium material according to any one of claims 2 to 3 in the preparation of anode catalyst material for proton exchange membrane water electrolysis to produce hydrogen.

5. A proton exchange membrane anode for hydrogen production via water electrolysis, characterized in that, It includes an anode support and an anode catalyst material supported thereon, wherein the anode catalyst material is the two-dimensional carbonyl iridium material as described in any one of claims 2 to 3.

6. A method for producing hydrogen by proton exchange membrane electrolysis of water, characterized in that: It is applied to the proton exchange membrane electrolysis anode for hydrogen production as described in claim 5.

7. The method for producing hydrogen by proton exchange membrane electrolysis of water according to claim 6, characterized in that: in, 0.1M HClO4 solution was used as the electrolyte, and platinum mesh and Ag / AgCl electrode were used as the counter electrode and reference electrode, respectively.

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