METHOD FOR PRODUCING IRIDIUM NANOCRYSTALS

Abstract

The present application provides a manufacturing method for an iridium nanocrystal, including the following steps: mixing an iridium salt, an alcohol solvent, and a liquid centrifuge residue to form a mixed solution, and adding an alkaline solution in an inert atmosphere for a heating reaction. After centrifugation, an iridium nanocrystal is obtained. The liquid centrifuge residue is a liquid residue produced in the iridium nanocrystal presynthesis process. This manufacturing method can shorten the reaction time, and the resulting iridium nanocrystal has the advantages of high yield and low cost.

Description

[0001] This application claims priority to Chinese Patent Application No. 202211595336.8, entitled "METHOD OF PREPARING IRIDIUM NANOCRYSTAL," filed with the Chinese Patent Office (CNIPA) on December 13, 2022. The disclosure of said application is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0002] The present application belongs to the technical field of electrochemistry and more specifically to a method for producing an iridium nanocrystal. GENERAL STATE OF THE ART

[0003] Hydrogen production through water electrolysis is a major route for hydrogen production from renewable energy sources. Hydrogen production through water electrolysis using a proton exchange membrane (PEM) can occur at high current densities, which has the advantages of small volume, high efficiency, and high purity of the produced hydrogen; and it can be used on a large scale. Hydrogen production through water electrolysis requires a catalyst to reduce the possibility of electrochemical reactions. The catalytic activity and cost of a catalyst for an anode for PEM water electrolysis are important factors limiting the further development of hydrogen production through PEM water electrolysis.

[0004] Compared with base metal catalysts such as nickel, cobalt, and iron, iridium (Ir) catalysts exhibit higher activity in acidic oxygen evolution reactions, thus being considered the most suitable catalyst for the anode of PEM water electrolysis. Iridium has a low energy barrier for homogeneous nucleation, which directly translates into the propensity of the iridium atom to self-nucleate and grow into small particles during iridium catalyst synthesis. Due to the small size of the small particles, separation is difficult, which is not conducive to improving the utilization rate of iridium nanocrystals. Furthermore, iridium resources are scarce, expensive, and expensive.

[0005] Currently, the catalytic activity of iridium nanocrystals is being improved by doping and loading with other base metal materials, and the cost of iridium nanocrystals is being reduced. However, the degree of improvement in catalytic activity and the cost of iridium nanocrystals are still far from meeting demand. Therefore, the method by which iridium nanocrystals with high catalytic activity and low cost can be obtained has long been a subject of research. DEMOLITION

[0006] The present application provides a manufacturing process for an iridium nanocrystal. Recycling the liquid residue generated during the pre-synthesis of iridium nanocrystals can shorten the reaction time. It is possible to produce iridium nanocrystals with high catalytic activity and have the advantages of high yield, low cost, etc.

[0007] The present application provides a manufacturing method for an iridium nanocrystal, which includes the following steps: Mixing an iridium salt, an alcohol solvent, and a liquid centrifuge residue to form a mixed solution, and adding an alkali solution in an inert atmosphere for a heating reaction, centrifuging to obtain an iridium nanocrystal, wherein the heating reaction is carried out under a temperature condition of 140-220 °C and for a duration not exceeding 6 h; a volume of the liquid centrifuge residue is 10-50% of a volume of the mixed solution; and the liquid centrifuge residue is a liquid residue produced by an iridium nanocrystal presynthesis process.

[0008] According to one embodiment of the present application, the mixed solution is heated to 120-220 °C in the inert atmosphere, and then the alkali solution is added.

[0009] According to one embodiment of the present application, the heating reaction preferably lasts 1-5 h.

[0010] According to one embodiment of the present application, the heating reaction preferably lasts 1.5-2 h.

[0011] According to one embodiment of the present application, the volume of the liquid centrifuge residue is preferably 15-40% of the volume of the mixed solution.

[0012] According to one embodiment of the present application, a mass content of the iridium salt in the mixed solution is 0.02% to 0.1%.

[0013] According to one embodiment of the present application, an average particle size of the iridium nanocrystal is 5-60 nm.

[0014] According to one embodiment of the present application, the liquid centrifuge residue is a liquid residue produced by a primary iridium nanocrystal synthesis process.

[0015] According to one embodiment of the present application, the iridium salt includes at least one of iridium trichloride, iridium tetrachloride, chloroiridic acid, and iridium acetate.

[0016] According to one embodiment of the present application, the volume of the liquid centrifuge residue is 10-50% of the volume of the mixed solution.

[0017] According to one embodiment of the present application, a molar ratio of the alcohol solvent to the iridium salt is (8000-14000):1.

[0018] According to one embodiment of the present disclosure, the mixed solution also includes an organic ligand, and the organic ligand includes at least one of ethylenediamine, polyacrylamide, citric acid, and malic acid.

[0019] According to one embodiment of the present application, a molar ratio of the organic ligand to the iridium salt is (0.05-5):1.

[0020] According to one embodiment of the present application, the heating reaction is carried out under a temperature condition of 140-220 °C and for a duration not exceeding 6 h.

[0021] The implementation of the present application has at least the following advantageous effects: The present application provides a method for producing an iridium nanocrystal, wherein the liquid centrifuge residue produced during the iridium nanocrystal presynthesis process contains the alcohol solvent and an iridium precursor that was not separated by centrifugation. In the present application, the liquid centrifuge residue produced in the iridium nanocrystal presynthesis process is recycled, and the iridium salt, the alcohol solvent, and the liquid centrifuge residue are mixed for reaction, thereby fully utilizing the iridium precursor in the mixed solution and improving the yield of iridium nanocrystal synthesis. This production method can shorten the heating reaction time. At the same time, it can realize the efficient reuse of the iridium precursor in the liquid centrifuge residue and greatly reduce production costs.In addition, the manufacturing process also has the advantage of simple processing and simple operation, which is conducive to industrial production and application. SHORT DESCRIPTION OF DRAWINGS Fig. 1 is a transmission electron microscope (TEM) image of an iridium nanocrystal S1 in Example 1 of the present application. Fig. Figure 2 is a TEM image of iridium nanocrystals S2 in Example 2 of the present application. Fig. 3 is a TEM image of iridium nanocrystals S11 in Comparative Example 1 of the present application. Fig. 4 is a TEM image of iridium nanocrystals S12 in Comparative Example 2 of the present application. Fig. 5 is a graph of a polarization curve of an oxygen evolution reaction of iridium nanocrystal in Example 2 and Comparative Example 1. DESCRIPTION OF EMBODIMENTS

[0022] The specific embodiments listed below are intended only to describe the principles and features of the present application, and the examples are provided only to illustrate the present application, not to limit the scope of the present application. Based on the embodiments of the present application, all other embodiments that can be obtained by those of ordinary skill in the art without creative effort are within the scope of the present application.

[0023] The method for producing an iridium nanocrystal disclosed in the present application includes: mixing an iridium salt, an alcohol solvent, and a liquid centrifuge residue to form a mixed solution, and adding an alkali solution in an inert atmosphere for a heating reaction, centrifuging to obtain an iridium nanocrystal, wherein the heating reaction is carried out under a temperature condition of 140-220 °C and for a duration not exceeding 6 hours; a volume of the liquid centrifuge residue is 10-50% of a volume of the mixed solution; and the liquid centrifuge residue is a liquid residue produced by the iridium nanocrystal presynthesis process.

[0024] In the iridium nanocrystal synthesis process, the liquid centrifuge residue contains the iridium precursor that cannot be separated by centrifugation and the alcohol solvent, resulting in high waste disposal costs. Through research, the applicant has found that introducing the liquid centrifuge residue produced in the iridium nanocrystal presynthesis process into the iridium nanocrystal synthesis process can not only realize the recycling of the liquid centrifuge residue, thereby reducing the loss of the precious metal iridium and lowering production costs, but also fully utilize the iridium source in the mixed solution, thereby improving the yield of the iridium nanocrystal synthesis. Furthermore, the liquid centrifuge residue can also provide part of the solvent, thereby reducing the amount of fresh alcohol solvent consumed and further reducing production costs.

[0025] In the present application, a manufacturing process for iridium nanocrystals includes at least a primary synthesis and a secondary synthesis, and the primary synthesis is a pre-synthesis of the secondary synthesis. The liquid centrifuge residue used in the secondary synthesis is a liquid residue produced during the primary iridium nanocrystal synthesis. Since the liquid centrifuge residue contains the unreacted ethylene glycol and the iridium precursor, recycling them not only solves the problem of environmental pollution due to pollutant discharge but also improves the utilization rate of ethylene glycol and the iridium precursor with high added value.

[0026] Synthesizing iridium nanocrystals with a specific structure is an effective way to enhance their catalytic activity. An additional amount of liquid centrifuge residue affects the structure of the iridium nanocrystal. If the added amount of liquid centrifuge residue is too large, the iridium nanocrystal easily forms aggregates, resulting in an irregular shape that is not conducive to the catalytic activity of the iridium nanocrystal. If the added amount of liquid centrifuge residue is too small, it is not conducive to the recycling of liquid centrifuge residue.

[0027] In one embodiment, a volume of the liquid centrifuge residue is 10-50% of a volume of the mixed solution, for example, in a range formed by any two of 10%, 20%, 30%, 40%, and 50%.

[0028] In the present application, by adding the liquid centrifuge residue, the reaction rate can be increased and the reaction time can be shortened. For example, if the volume of the liquid centrifuge residue is 15% of the volume of the mixed solution, the reaction time can be shortened to 2 hours. If the volume of the liquid centrifuge residue is 40% of the volume of the mixed solution, the reaction time can be shortened to 1.5 hours. To improve the yield of iridium nanocrystals, pre-synthesis is preferably performed as the primary synthesis.

[0029] When the pre-synthesis is the primary synthesis, the liquid centrifuge residue is the liquid residue produced in the primary iridium nanocrystal synthesis; and the method for producing the iridium nanocrystal includes at least: (1) Mixing a first iridium salt and a first alcohol solvent to form a first mixed solution, adding an alkali solution in an inert atmosphere, conducting a first heating reaction, and conducting a first centrifugation to obtain a solid phase and a liquid centrifuge residue; (2) Mixing a second iridium salt, a second alcohol solvent, and the liquid centrifuge residue to form a second mixed solution, adding an alkali solution in an inert atmosphere, conducting a second heating reaction, and conducting a second centrifugation to obtain the iridium nanocrystal.

[0030] The mass of the first iridium salt and the mass of the second iridium salt can be the same or different. To further improve the yield of iridium nanocrystals, it is preferable for them to be the same.

[0031] The volume of the first mixed solution and the volume of the second mixed solution may be the same or different. To further improve the yield of iridium nanocrystals, it is preferable that they be the same.

[0032] The conditions for the first heating reaction and the second heating reaction may be the same or different.

[0033] In the present application, a mass content of the iridium salt in the mixed solution is 0.02% to 0.1%, such as 0.02%, 0.05%, 0.1%, or a range formed by any two thereof.

[0034] The present application does not limit the specific type of iridium salt, for example, the iridium salt includes at least one of chloroiridic acid, iridium acetate and iridium tetrachloride.

[0035] In the present application, the iridium salt can first be dissolved in the alcohol solvent to prepare an iridium salt solution, and then the iridium salt solution is mixed with the liquid centrifuge residue to obtain the mixed solution. During the dissolution process, the air in the system is removed as much as possible by filling with nitrogen to ensure that the resulting material is not oxidized by oxygen in the air during the synthesis process. The nitrogen filling time can be 30-60 minutes, and stirring can be performed throughout the process to facilitate more uniform mixing of the iridium salt and the alcohol solvent.

[0036] In the manufacturing process for an iridium nanocrystal, the alcohol solvent acts as a solvent on the one hand and as a reducing agent on the other hand to promote the reduction of the iridium salt to the iridium nanocrystal.

[0037] The present application does not limit the specific type of alcohol solvent, for example, the alcohol solvent includes at least one of ethylene glycol, diethylene glycol and ethanol.

[0038] To ensure that the iridium salt can be completely reduced, the alcohol solvent is present in excess relative to the iridium salt. In some embodiments, the molar ratio of the alcohol solvent to the iridium salt is (8000-14000):1, for example, 8000:1, 8100:1, 8500:1, 9500:1, 10000:1, 11000:1, 12000:1, 14000:1, or in a range formed by any two of these.

[0039] In the present application, the mixed solution also includes an organic ligand, and the organic ligand is capable of regulating the morphology of the iridium nanocrystal by limiting the growth of the iridium nanocrystal, thereby controlling the size of the iridium nanocrystal.

[0040] The present application does not limit the specific nature of the organic ligand, which may be any organic ligand commonly used in the art, such as a compound containing an amine group and / or a carboxylic acid group. Furthermore, the organic ligand includes, but is not limited to, at least one of ethylenediamine, polyacrylamide, citric acid, and malic acid, among others.

[0041] The size of the iridium nanocrystal can be controlled by adjusting the amount of organic ligand added. In some embodiments, the molar ratio of the organic ligand to the iridium salt is (0.05-10):1, preferably (0.05-5):1, for example, 0.05:1, 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, or within a range formed by any two of these.

[0042] In the present application, the pH is adjusted by adding an alkali solution, and the amount of alkali solution added is determined according to the amount of the mixed solution. When the volume of the mixed solution is 90 ml, the amount of alkali solution added can be 5 ml to 10 ml.

[0043] The present application does not limit the specific type of alkali solution. The alkali solution contains an alkaline compound and includes, but is not limited to, the solution containing at least one of sodium hydroxide and potassium hydroxide.

[0044] In some embodiments, a molar ratio of the alkali compound to the iridium salt is (0.1-1):1, for example, 0.1:1, 0.2:1, 0.4:1, 0.6:1, 0.8:1, 1:1, or in a range formed by any two thereof.

[0045] Before adding the alkali solution, the mixed solution can be heated first, for example, the mixed solution can be heated to 120 °C first, and then the alkali solution is added.

[0046] In the present application, the iridium salt is reduced to form the iridium nanocrystal through the heating reaction of the mixed solution to which the alkali solution is added. During the heating process, the air in the system is removed as much as possible by filling it with nitrogen to ensure that the resulting material is not oxidized by oxygen in the air during the synthesis process.

[0047] The conditions for the heating reaction include a temperature of 140-220 °C, preferably 140-180 °C, and a duration not exceeding 6 hours, preferably 3-4 hours. The heating reaction can be carried out in a manner that involves gradual heating, for example, by heating to 140-220 °C at a heating rate of 2 °C / min. After the heating reaction is over, the temperature is cooled naturally or forcibly to room temperature.

[0048] The present application is not limited to centrifugation and can be any centrifugation method commonly used in the art. In one embodiment of the present application, the centrifugation speed is 18,000 rpm.

[0049] The present application also includes washing and drying the solid phase obtained by centrifugation to obtain the iridium nanocrystal. In one embodiment of the present application, the iridium nanocrystal is obtained by washing the solid phase several times with water and then vacuum drying at 90°C.

[0050] In the present application, the finally obtained iridium nanocrystal has an average particle size of 5-60 nm. The nanomaterial exhibits excellent electrocatalytic properties, such as oxygen evolution. Specifically, the iridium nanocrystal has an average particle size of 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, or a range formed by any two of these.

[0051] The iridium nanocrystal disclosed in the present application can recycle the liquid centrifuge residue produced by the pre-synthesis of the iridium nanocrystal. By mixing the iridium salt, the alcohol solvent, and the liquid centrifuge residue, the iridium precursor in the mixed solution can be fully utilized and the yield of iridium nanocrystal synthesis can be improved. Furthermore, it is possible to realize the efficient reuse of the iridium precursor in the liquid centrifuge residue, and the liquid centrifuge residue can also provide part of the solvent, thereby reducing the consumption of fresh alcohol solvent and further reducing production costs.

[0052] Hereinafter, the method for producing the iridium nanocrystal of the present application will be described in detail by concrete examples.

[0053] The individual raw materials of the following examples and comparative examples are as follows: Chloriridic acid: a purity of 99.98%; Ethylene glycol: anhydrous grade, 99.8% purity; NaOH solution: a mass concentration of 0.01 mol / l. Example 1 (1) 200 mg of chloroiridic acid was added to 90 mL of ethylene glycol to obtain an iridium salt solution, and N2 was introduced into the iridium salt solution for 60 min while maintaining the N2 atmosphere and stirring thoroughly. The solution was heated to 120 °C at a heating rate of 2 °C / min, followed by injection of 10 mL of NaOH solution, heating to 150 °C, maintaining the temperature for 3 h, and then cooling to room temperature. A first solid phase and a liquid residue were then obtained by centrifugation using a high-speed centrifuge; and after the first solid phase was washed and vacuum-dried at 90 °C for 24 h, an iridium nanocrystal sample was taken. (2) 200 mg of chloroiridic acid was dissolved in 10 mL of ethylene glycol, with stirring during the dissolution process. After the dissolution was complete, the solution was transferred to 60 mL of ethylene glycol. Another 20 mL of the liquid centrifuge residue was added, at which time the total volume of the solution was 90 mL. N2 was introduced into the solution for 60 min, maintaining the N2 atmosphere and stirring thoroughly. The solution was heated to 120 °C at a heating rate of 2 °C / min, followed by the addition of 10 mL of NaOH solution, heating to 150 °C, holding the temperature for 2 h, and then cooling to room temperature.Then, a second solid phase was collected by centrifugation using a high-speed centrifuge; and after the second solid phase was washed and vacuum-dried at 90 °C for 24 h, an iridium nanocrystal sample S1 was obtained (a TEM image of the iridium nanocrystal S1 was shown in ). Fig. 1 shown). Example 2

[0054] The preparation process is essentially the same as in Example 1, except that in step (2), 200 mg of chloroiridic acid is added to 50 ml of ethylene glycol with stirring during the dissolution process; after complete dissolution, 40 ml of the liquid centrifuge residue is added; and 6 ml of NaOH solution is added, keeping other conditions unchanged. An iridium nanocrystal sample S2 is obtained (a TEM image of the iridium nanocrystal sample S2 is shown in Fig. 2 shown). Example 3

[0055] The preparation process is essentially the same as in Example 1, except that in step (2), 200 mg of chloroiridic acid and 0.08 mmol of citric acid are added to 70 ml of ethylene glycol with stirring during the dissolution process; after complete dissolution, 20 ml of the liquid centrifuge residue is added; and 8 ml of NaOH solution is injected, keeping other conditions unchanged. An iridium nanocrystal sample S3 is obtained. Example 4

[0056] The preparation method is essentially the same as in Example 1, except that in step (2), 200 mg of chloroiridic acid and 0.08 mmol of citric acid are added to 50 ml of ethylene glycol with stirring during the dissolution process; after complete dissolution, 40 ml of the liquid centrifuge residue is added; and 6 ml of NaOH solution is injected, keeping other conditions unchanged. An iridium nanocrystal sample S4 is obtained. Example 5

[0057] The preparation process is essentially the same as in Example 1, except that in step (2), 200 mg of chloroiridic acid and 0.08 mmol of ethylenediamine are dissolved in 70 ml of ethylene glycol, stirring during the dissolution process; after complete dissolution, 20 ml of the liquid centrifuge residue is added; and 8 ml of NaOH solution is injected, keeping other conditions unchanged. An iridium nanocrystal sample S5 is obtained. Example 6

[0058] The preparation method is essentially the same as in Example 1, except that in step (2), 0.04 mmol of iridium acetate is added to 70 ml of ethylene glycol with stirring during the dissolution process; after complete dissolution, 20 ml of the liquid centrifuge residue is added, 8 ml of NaOH solution is injected, and the heating reaction temperature is 160 °C, with other conditions remaining unchanged. An iridium nanocrystal sample S6 is obtained. Example 7

[0059] The preparation method is essentially the same as in Example 1, except that in step (2), 0.04 mmol of iridium acetate and 0.08 mmol of citric acid are added to 70 ml of ethylene glycol with stirring during the dissolution process; after complete dissolution, 20 ml of the liquid centrifuge residue is added, and 8 ml of NaOH solution is added. The heating reaction temperature is 160 °C, with other conditions remaining unchanged. An iridium nanocrystal sample S7 is obtained. Example 8

[0060] The preparation method is essentially the same as in Example 1, except that in step (2), 0.04 mmol of iridium acetate is added to 60 ml of ethylene glycol to obtain an iridium acetate solution, 0.08 mmol of citric acid is dissolved in 10 ml of ethylene glycol to obtain a citric acid solution, and then the iridium acetate solution is mixed with citric acid solution, stirring during the dissolution process. After complete dissolution, 20 ml of the liquid centrifuge residue is added to the mixed solution, 8 ml of NaOH solution is injected, and the heating reaction temperature is 160 °C, with other conditions remaining unchanged. An iridium nanocrystal sample S8 is obtained. Example 9

[0061] The preparation method is essentially the same as in Example 1, except that in step (2), 0.04 mmol of iridium tetrachloride is added to 70 ml of ethylene glycol with stirring during the dissolution process; after complete dissolution, 20 ml of the liquid centrifuge residue is added, 8 ml of NaOH solution is injected, and the heating reaction temperature is 170 °C, with other conditions remaining unchanged. An iridium nanocrystal sample S9 is obtained. Example 10

[0062] The preparation method is essentially the same as in Example 1, except that in step (2), 0.04 mmol of iridium tetrachloride is added to 60 ml of ethylene glycol to obtain an iridium acetate solution, 0.08 mmol of citric acid is added to 10 ml of ethylene glycol to obtain a citric acid solution, and then the iridium tetrachloride solution is mixed with the citric acid solution, stirring during the dissolution process. After complete dissolution, 20 ml of the liquid centrifuge residue is added to the mixed solution, 8 ml of NaOH solution is injected, and the heating reaction temperature is 170 °C, with other conditions remaining unchanged. An iridium nanocrystal sample S10 is obtained. Comparison example 1

[0063] 200 mg of chloroiridic acid was added to 90 mL of ethylene glycol to obtain an iridium salt solution, and N2 was introduced into the iridium salt solution for 60 min while maintaining the N2 atmosphere and stirring thoroughly. The solution was heated to 120 °C at a heating rate of 2 °C / min, followed by injection of 10 mL of NaOH solution, heating to 150 °C, maintaining the temperature for 3 h, and then cooling to room temperature. A first solid phase and a liquid residue were then obtained by centrifugation using a high-speed centrifuge; and after the first solid phase was washed and vacuum-dried at 90 °C for 24 h, an iridium nanocrystal solution S11 was collected (a TEM image of S11 was shown in Fig. 3 shown). Comparison example 2

[0064] The preparation process is essentially the same as that of Example 1, except that in step (2), 200 mg of chloroiridic acid is added to 30 ml of ethylene glycol with vigorous stirring during the dissolution process; after complete dissolution, 60 ml of the liquid centrifuge residue is added; other conditions remain unchanged. An iridium nanocrystal sample S12 is obtained (a TEM image of S12 is shown in Fig. 4 shown). Test example

[0065] The test procedure for an oxygen evolution reaction polarization curve includes the following: (1) Weighing 5 mg of catalyst, sequentially adding 250 µl of isopropyl alcohol and 250 µl of Nafion diluent and sonicating for 30 min to achieve uniform mixing of a slurry; (2) uniformly dropping an appropriate amount of dispersed slurry onto a smooth and clean surface of a disc electrode and allowing it to dry naturally to obtain a working electrode; (3) Using a three-electrode system for the test procedure, wherein a rotational speed of the disk electrode is 1600 rpm, and activating the catalyst by cyclic voltammetry in a suitable voltage range until the catalyst reaches a stable state, wherein the measurement is carried out in the potential range of 1.23-1.60 V at the scanning rate of 1 mV s-1 (with respect to the reversible hydrogen electrode, RHE).

[0066] The method for calculating the yield of iridium nanocrystal: the yield is a ratio of a mass of iridium nanocrystal actually obtained to a mass of iridium nanocrystal theoretically obtained from the fed iridium salt.

[0067] The raw materials for preparation in the examples and comparative examples as well as the yield of iridium nanocrystal are shown in Table 1.

[0091] Table 1: sample Iridium salt Organic ligand Amount of liquid centrifuge residue used ml Yield of iridium nanocrystal product % S1 Chloriridic acid no 20 88 S2 Chloriridic acid no 40 90 S3 Chloriridic acid Citric acid 20 92 S4 Chloriridic acid Citric acid 40 93 S5 Chloriridic acid Ethylenediamine 20 95 S6 Iridium acetate no 20 89 S7 Iridium acetate Citric acid 20 90 S8 Iridium acetate Ethylenediamine 20 92 S9 Iridium tetrachloride no 20 87 S10 Iridium tetrachloride Citric acid 20 88 S11 Chloriridic acid no 0 80 S12 Chloriridic acid no 60 75

[0068] From Table 1, it can be seen that the iridium nanocrystal provided in the present application has a higher synthesis yield, and according to Fig. 5, the iridium nanocrystal prepared in Example 2 of the present application has a higher catalytic activity.

[0069] Finally, it should be clarified that the above embodiments are used only to illustrate the technical solution of the present application and do not serve to limit the present application. Although the present application has been described in detail with reference to the above embodiments, those of ordinary skill in the art will understand that they may modify the technical solutions presented in the above embodiments or make equivalent substitutions for some or all of the technical features thereof; such modification or substitution should not cause the essence of the technical solution to deviate from the respective scope of the technical solutions of embodiments of the present application. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 202211595336.8

[0001]

Claims

[1] A manufacturing method for an iridium nanocrystal, comprising the following steps: Mixing an iridium salt, an alcohol solvent, and a liquid centrifuge residue to form a mixed solution, and adding an alkali solution in an inert atmosphere for a heating reaction, centrifuging to obtain an iridium nanocrystal, wherein the heating reaction is carried out under a temperature condition of 140-220 °C and for a duration not exceeding 6 h; a volume of the liquid centrifuge residue is 10-50% of a volume of the mixed solution; and the liquid centrifuge residue is a liquid residue produced by an iridium nanocrystal presynthesis process. [2] The manufacturing method according to claim 1, wherein the mixed solution is heated to 120-220 °C in the inert atmosphere and then the alkali solution is added. [3] The manufacturing method according to claim 1 or 2, wherein the heating reaction has a duration of 1-5 hours. [4] A manufacturing process according to any one of claims 1-3, wherein the heating reaction has a duration of 1.5-2.5 h. [5] A manufacturing method according to any one of claims 1-4, wherein the volume of the liquid centrifuge residue is 15-40% of the volume of the mixed solution. [6] The manufacturing method according to any one of claims 1-5, wherein a mass content of the iridium salt in the mixed solution is 0.02% - 0.1%. [7] The manufacturing method according to any one of claims 1-6, wherein an average particle size of the iridium nanocrystal is 5-60 nm. [8] The manufacturing method according to any one of claims 1-7, wherein the liquid centrifuge residue is a liquid residue produced by a primary iridium nanocrystal synthesis process. [9] The manufacturing method according to any one of claims 1-8, wherein the iridium salt includes at least one of iridium trichloride, iridium tetrachloride, chloroiridic acid and iridium acetate. [10] The manufacturing method according to any one of claims 1-9, wherein the alkali solution contains an alkaline compound and a molar ratio of the alkaline compound to the iridium salt is (0.1-1):

1. [11] The manufacturing method according to any one of claims 1-10, wherein a molar ratio of the alcohol solvent to the iridium salt is (8000-14000):

1. [12] The manufacturing method according to any one of claims 1-11, wherein the mixed solution also contains an organic ligand; and the organic ligand includes at least one of ethylenediamine, polyacrylamide, citric acid, and malic acid. [13] The manufacturing method according to claim 12, wherein a molar ratio of the organic ligand to the iridium salt is (0.05-5):1.

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