Fluorine-doped iridium oxide catalyst as well as preparation method and application thereof
Through the preparation method of fluorine-doped iridium oxide catalyst, the problem of slow kinetics of the existing iridium oxide catalyst during PEMWE electrolysis was solved, and a catalyst with small particle size and high activity was prepared, and the kinetics of the oxygen precipitation reaction were optimized.
Patent Information
- Application Number
- CN202510319645.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-17
AI Technical Summary
The existing iridium oxide catalysts have slow kinetics of anodic oxygen precipitation during PEMWE electrolysis, and the prepared iridium dioxide particles are large in size or surface additive coating, which affects the catalytic activity.
Using the preparation method of fluorine-doped iridium oxide catalyst, a fluorine-doped iridium dioxide catalyst with small particle size and high atomic utilization rate is prepared by mixing a carbon nitride support with an iridium salt and a fluorine source, and after drying and calcining steps.
The catalyst has small particle size and high atom utilization rate, optimized the proton desorption step, accelerated the kinetics of acid oxygen precipitation reaction, and improved catalytic activity.
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Figure CN120158770A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalysts, and particularly relates to a fluorine-doped iridium oxide catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] Proton exchange membrane electrolysis (PEMWE) water electrolysis for hydrogen production is one of the key technologies to help achieve the "dual carbon" goal. It can couple and utilize renewable energy, and has advantages such as fast response speed, high current density, and high gas purity, and has received extensive attention at home and abroad. However, the anodic oxygen evolution reaction in the PEMWE water electrolysis process involves multiple steps of proton desorption and electron transfer processes, and the kinetics is slow.
[0003] Iridium-based oxide catalysts can withstand the strong acid and strong oxidation environment of the PEMWE system and have good oxygen evolution reaction activity, and are currently the mainstream anodic catalysts. At present, the preparation methods of iridium oxides mainly include Adams melting method, polyol method, sol-gel method, etc. The Adams melting method is to mix the iridium precursor with a large amount of low-melting salts and calcine, and obtain iridium dioxide particles after washing with water. The polyol method is to obtain elemental iridium through the reduction of polyols, and then obtain iridium dioxide particles through oxidative calcination. The sol-gel method prepares iridium dioxide particles by restricting the nucleation and growth of particles with surfactants. However, the iridium dioxide particles synthesized by the above methods have relatively large sizes or there is a phenomenon of surface additive coating, which is not conducive to the expression of catalyst activity. Summary of the Invention
[0004] In order to solve the above problems, the present invention provides a fluorine-doped iridium oxide catalyst, a preparation method thereof, and an application thereof. The fluorine-doped iridium dioxide catalyst has small particle size, high atomic utilization rate, and high catalytic activity.
[0005] In order to achieve the above object, the present invention provides the following technical solutions:
[0006] The present invention provides a preparation method of a fluorine-doped iridium oxide catalyst, comprising the following steps:
[0007] 1) Calcining a carbon nitride precursor to obtain a carbon nitride support, and dispersing the carbon nitride support in water to obtain a carbon nitride support dispersion;
[0008] 2) Mixing the carbon nitride support dispersion obtained in step 1) with an iridium salt solution and a fluorine source, and drying to obtain a catalyst precursor;
[0009] 3) Calcining the catalyst precursor obtained in step 2) to obtain a fluorine-doped iridium oxide catalyst.
[0010] Preferably, the carbon nitride precursor in step 1) includes one or more of urea, cyanamide, dicyandiamide, and melamine;
[0011] The roasting temperature is 500 - 550 °C, the time is 2 h, and the heating rate is 3 °C / min.
[0012] Preferably, the concentration of the carbon nitride support dispersion liquid in step 1) is 2 mg / mL.
[0013] Preferably, the iridium salt in the iridium salt solution in step 2) includes one or more of iridium trichloride, iridic acid, sodium hexachloroiridate, and iridium acetate;
[0014] The concentration of the iridium salt solution is 10 mg / mL.
[0015] Preferably, the fluorine source in step 2) includes one or more of ammonium fluoride, sodium fluoride, and polyvinylidene fluoride.
[0016] Preferably, the volume ratio of the carbon nitride support dispersion liquid, the volume of the iridium salt solution, and the mass ratio of the fluorine source in step 2) is 25 mL: 1.94 mL: 25 - 125 mg.
[0017] Preferably, the drying conditions in step 2) include rotary evaporation drying or drying in an oven, and the drying temperature is 50 - 80 °C.
[0018] Preferably, the calcination conditions in step 3) include: the temperature is 450 °C, the time is 2 h, and the heating rate is 3 °C / min.
[0019] The present invention also provides a fluorine-doped iridium oxide catalyst prepared by the preparation method described in the above technical solution.
[0020] The present invention also provides the application of the fluorine-doped iridium oxide catalyst described in the above technical solution in the oxygen evolution reaction of electrolyzed water.
[0021] Advantages of the present invention:
[0022] Compared with the prior art, the preparation method provided by the present invention is simple and controllable in operation, which is conducive to large-scale industrial production. The fluorine-doped iridium dioxide catalyst includes iridium dioxide nanoparticles and fluorine atoms doped in the iridium dioxide nanoparticles. The catalyst has small particle size and high atomic utilization rate; the doping of fluorine atoms can optimize the proton desorption step in the reaction process, accelerate the reaction kinetics of the acidic oxygen evolution OER reaction, and improve the intrinsic activity. The fluorine-doped iridium dioxide catalyst prepared by the present invention has excellent reaction activity in the OER reaction. Description of the Drawings
[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments.
[0024] Figure 1Transmission electron microscopy image of the F-IrO2-1 catalyst with fluorine-doped iridium dioxide in Example 1;
[0025] Figure 2 Transmission electron microscopy image of the F-IrO2-2 catalyst with fluorine-doped iridium dioxide in Example 2;
[0026] Figure 3 Element distribution map of the F-IrO2-2 catalyst with fluorine-doped iridium dioxide in Example 2;
[0027] Figure 4 X-ray diffraction pattern of the F-IrO2-2 catalyst with fluorine-doped iridium dioxide in Example 2;
[0028] Figure 5 Linear sweep voltammetry curve of electrochemical oxygen evolution of the F-IrO2-2 catalyst with fluorine-doped iridium dioxide in Example 2;
[0029] Figure 6 Transmission electron microscopy image of the F-IrO2-3 catalyst with fluorine-doped iridium dioxide in Example 3;
[0030] Figure 7 Transmission electron microscopy image of the F-IrO2-5 catalyst with fluorine-doped iridium dioxide in Example 5;
[0031] Figure 8 Transmission electron microscopy image of the IrO2 catalyst in the comparative example. Detailed implementation mode
[0032] The present invention provides a preparation method of a fluorine-doped iridium oxide catalyst, comprising the following steps:
[0033] 1) Calcining a carbon nitride precursor to obtain a carbon nitride support, and dispersing the carbon nitride support in water to obtain a carbon nitride support dispersion;
[0034] 2) Mixing the carbon nitride support dispersion obtained in step 1) with an iridium salt solution and a fluorine source, and drying to obtain a catalyst precursor;
[0035] 3) Calcining the catalyst precursor obtained in step 2) to obtain a fluorine-doped iridium oxide catalyst.
[0036] The present invention calcines a carbon nitride precursor to obtain a carbon nitride support, and disperses the carbon nitride support in water to obtain a carbon nitride support dispersion. In the present invention, the carbon nitride precursor preferably includes one or more of urea, cyanamide, dicyandiamide, and melamine. In the present invention, the calcination temperature is preferably 500-550 °C, the time is preferably 2 h, and the heating rate is preferably 3 °C / min. In the present invention, the concentration of the carbon nitride support dispersion is preferably 2 mg / mL. The present invention preferably grinds the carbon nitride precursor in a mortar to a fine powder and then performs calcination. The present invention preferably disperses the carbon nitride support in water and then sonifies for half an hour.
[0037] The present invention mixes the obtained carbon nitride support dispersion with an iridium salt solution and a fluorine source, and dries to obtain a catalyst precursor. In the present invention, the iridium salt in the iridium salt solution preferably includes one or more of iridium trichloride, chloroiridic acid, sodium chloroiridate, and iridium acetate. In the present invention, the concentration of the iridium salt solution is preferably 10 mg / mL. The present invention preferably dissolves the iridium salt in water and then sonifies for 1 h. In the present invention, the fluorine source preferably includes one or more of ammonium fluoride, sodium fluoride, and polyvinylidene fluoride. In the present invention, the volume ratio of the carbon nitride support dispersion to the volume of the iridium salt solution and the mass ratio of the fluorine source are preferably 25 mL:1.94 mL:25-125 mg. In the present invention, the drying conditions preferably include rotary evaporation drying or drying in an oven, and the drying temperature is preferably 50-80 °C.
[0038] The present invention calcines the obtained catalyst precursor to obtain a fluorine-doped iridium oxide catalyst. In the present invention, the calcination conditions preferably include: a temperature of 450 °C, a time of 2 h, and a heating rate of 3 °C / min.
[0039] The present invention also provides a fluorine-doped iridium oxide catalyst prepared by the preparation method described in the above technical solution.
[0040] The present invention also provides the application of the fluorine-doped iridium oxide catalyst described in the above technical solution in the oxygen evolution reaction of water electrolysis.
[0041] To further illustrate the present invention, the following examples are used to describe the present invention in detail, but they should not be construed as limiting the protection scope of the present invention.
[0042] Example 1
[0043] Weigh 5 g of urea, grind it to a fine powder in a mortar, then place it in a crucible and calcine it in a muffle furnace. Heat it to 500 °C at a rate of 3 °C / min and maintain it for 2 hours. After cooling to room temperature, a carbon nitride support is obtained.
[0044] After thoroughly grinding the above-mentioned carbon nitride support, 50 mg was taken and dispersed in 25 mL of deionized water, and ultrasonically treated for half an hour to obtain a uniform carbon nitride dispersion; meanwhile, 200 mg of iridium trichloride was dissolved in 20 mL of deionized water and ultrasonically treated for 1 hour to completely dissolve it, obtaining an IrCl3 precursor solution. Subsequently, 1.94 mL of the IrCl3 precursor solution was added to the above-mentioned carbon nitride dispersion, then 25 mg of ammonium fluoride was added, and after continuously stirring for 12 h, the catalyst precursor powder was obtained by rotary evaporation at 55 °C.
[0045] The above powder was placed in a quartz boat and calcined in a muffle furnace. It was heated to 450 °C at a heating rate of 3 °C / min, held at a constant temperature for 2 hours, and after cooling to room temperature, a fluorine-doped IrO2 catalyst was obtained, labeled as F-IrO2-1.
[0046] The F-IrO2-1 catalyst of Example 1 was analyzed by transmission electron microscopy, and the results are as Figure 1 shown. It can be seen from the figure that the particle sizes of the F-IrO2-1 catalyst in Example 1 are uniform, about 1.5 - 2.6 nm.
[0047] The F-IrO2-1 catalyst of Example 1 was configured into a slurry to coat and modify the working electrode. The method for preparing the slurry is as follows: 2 mg of the catalyst powder was dispersed into 200 μl of a mixed solution of isopropanol and water with a volume ratio of 1:1, 10 μl of a perfluorosulfonic acid solution with a mass fraction of 5% was added, and ultrasonically dispersed for 1 hour to obtain a uniform catalyst slurry. 3 μl was measured and coated on the glassy carbon electrode, and after drying, the working electrode modified with the catalyst was obtained; using a saturated Ag / AgCl electrode as the reference electrode and a carbon rod as the counter electrode, a three-electrode system electrochemical test was carried out in a nitrogen-saturated 0.5 mol / L sulfuric acid solution, and the OER performance was compared with commercial iridium dioxide IrO2-C. The results show that the overpotential of the F-IrO2-1 catalyst at a current density of 10 mA / cm 2 is 264 mV, showing better activity than the commercial IrO2-C catalyst (355 mV).
[0048] Example 2
[0049] Weigh 5 g of urea and place it in a mortar, grind it into a fine powder, and then place it in a crucible and calcine it in a muffle furnace. Heat it to 500 °C at a rate of 3 °C / min, maintain it for 2 hours, and after cooling to room temperature, a carbon nitride support is obtained.
[0050] After the carbon nitride carrier is fully ground, 50 mg is dispersed in 25 mL of deionized water and ultrasonicated for half an hour to obtain a uniform carbon nitride dispersion; at the same time, 200 mg of iridium trichloride is dissolved in 20 mL of deionized water and ultrasonicated for 1 hour to completely dissolve it to obtain an IrCl3 precursor solution. Subsequently, 1.94 mL of the IrCl3 precursor solution is added to the carbon nitride dispersion, followed by 50 mg of ammonium fluoride, and after continuous stirring for 12 hours, the catalyst precursor powder is obtained by rotary evaporation at 55°C.
[0051] The above powder was placed in a quartz boat and calcined in a muffle furnace. It was heated to 450°C at a heating rate of 3°C / min and kept at this temperature for 2 hours. After cooling to room temperature, a fluorine-doped IrO2 catalyst was obtained, which was marked as F-IrO2-2.
[0052] The F-IrO2-2 catalyst of Example 2 was analyzed by transmission electron microscopy. Figure 2 As shown in the figure, it can be seen that the particle size of the F-IrO2-2 catalyst in Example 2 is uniform, about 1.2 to 2.5 nm.
[0053] The F-IrO2-2 catalyst of Example 2 was subjected to EDS element distribution image analysis, and the results were as follows: Figure 3 As shown in the figure, it can be seen that the F, Ir, and O elements are evenly distributed in the obtained F-IrO2-2 catalyst, and the C and N signals come from a small amount of residue on the carbon nitride carrier.
[0054] The F-IrO2-2 catalyst of Example 2 was subjected to X-ray diffraction analysis, and the results were as follows: Figure 4 As shown in Figure 4, the diffraction peak of the F-IrO2-2 catalyst corresponds to the characteristic diffraction peak of IrO2, and no diffraction peaks of other phases such as iridium single substance are found.
[0055] The catalyst-modified working electrode was prepared in the same manner as in Example 1, and the test results in a three-electrode system were as follows: Figure 5 The results show that the F-IrO2-2 catalyst has a high 2 The overpotential is 251 mV, which is nearly 100 mV lower than 355 mV of the commercial IrO2-C catalyst, indicating that the F-IrO2-2 catalyst has excellent OER intrinsic activity.
[0056] Example 3
[0057] Weigh 5 g of urea into a mortar, grind into fine powder, then place in a crucible and calcine in a muffle furnace, raise the temperature to 500° C. at a rate of 3° C. / min, maintain for 2 hours, and cool to room temperature to obtain a carbon nitride carrier.
[0058] After thoroughly grinding the above-mentioned carbon nitride support, 50 mg was taken and dispersed in 25 mL of deionized water, and ultrasonicated for half an hour to obtain a uniform carbon nitride dispersion; meanwhile, 200 mg of iridium trichloride was dissolved in 20 mL of deionized water and ultrasonicated for 1 hour to completely dissolve it, obtaining an IrCl3 precursor solution. Subsequently, 1.94 mL of the IrCl3 precursor solution was added to the above-mentioned carbon nitride dispersion, then 125 mg of ammonium fluoride was added, and after continuously stirring for 12 h, the catalyst precursor powder was obtained by rotary evaporation at 55 °C.
[0059] The above powder was placed in a quartz boat and calcined in a muffle furnace. It was heated to 450 °C at a heating rate of 3 °C / min, held at a constant temperature for 2 hours, and after cooling to room temperature, a fluorine-doped IrO2 catalyst was obtained, labeled as F-IrO2-3.
[0060] The F-IrO2-3 catalyst of Example 3 was analyzed by transmission electron microscopy, and the results are as Figure 6 shown. The results are as Figure 6 shown. It can be seen from the figure that the F-IrO2-3 catalyst particles in Example 3 have uniform sizes, about 1.5 - 2.5 nm.
[0061] A working electrode modified with the catalyst was prepared by the same method as in Example 1, and linear sweep voltammetry tests were carried out under a three-electrode system. The results show that the overpotential of the F-IrO2-3 catalyst is 260 mV at a current density of 10 mA / cm 2 , showing better activity (355 mV) than the commercial IrO2-C catalyst.
[0062] Example 4
[0063] Weigh 5 g of dicyandiamide and place it in a mortar, grind it into a fine powder, then place it in a crucible and calcine it in a muffle furnace. Heat it to 550 °C at a rate of 3 °C / min and maintain it for 2 hours. After cooling to room temperature, a carbon nitride support is obtained.
[0064] After thoroughly grinding the above-mentioned carbon nitride support, 50 mg was taken and dispersed in 25 mL of deionized water, and ultrasonicated for half an hour to obtain a uniform carbon nitride dispersion; meanwhile, 200 mg of iridium trichloride was dissolved in 20 mL of deionized water and ultrasonicated for 1 hour to completely dissolve it, obtaining an IrCl3 precursor solution. Subsequently, 1.94 mL of the IrCl3 precursor solution was added to the above-mentioned carbon nitride dispersion, then 50 mg of ammonium fluoride was added, and after continuously stirring for 12 h, the catalyst precursor powder was obtained by rotary evaporation at 60 °C.
[0065] Place the above powder in a quartz boat and calcine it in a muffle furnace. Heat it to 450 °C at a heating rate of 3 °C / min, keep it at a constant temperature for 2 hours, and then cool it to room temperature to obtain a fluorine-doped IrO2 catalyst, labeled as F-IrO2-4. The transmission electron microscopy analysis results show that the particle size of the F-IrO2-4 catalyst is about 1.5 - 2.5 nm.
[0066] Prepare a working electrode modified with the catalyst by the same method as in Example 1, and perform linear sweep voltammetry testing under a three-electrode system. The results show that the overpotential of the F-IrO2-4 catalyst is 255 mV at a current density of 10 mA / cm 2 and it exhibits better activity (355 mV) than the commercial IrO2-C catalyst.
[0067] Example 5
[0068] Weigh 5 g of urea and place it in a mortar, grind it into a fine powder, and then place it in a crucible and calcine it in a muffle furnace. Heat it to 500 °C at a rate of 3 °C / min, maintain it for 2 hours, and then cool it to room temperature to obtain a carbon nitride support.
[0069] After thoroughly grinding the above carbon nitride support, take 50 mg and disperse it in 25 mL of N-methylpyrrolidone, and ultrasonicate for half an hour to obtain a uniform carbon nitride dispersion; at the same time, take 200 mg of iridium trichloride and dissolve it in 20 mL of deionized water, and ultrasonicate for 1 hour to completely dissolve it to obtain an IrCl3 precursor solution. Subsequently, take 1.94 mL of the IrCl3 precursor solution and add it to the above carbon nitride dispersion, then add 25 mg of polyvinylidene fluoride, continuously stir for 8 h, and then place it in a blast drying oven at 80 °C to dry to obtain a catalyst precursor powder.
[0070] Place the above powder in a quartz boat and calcine it in a muffle furnace. Heat it to 450 °C at a heating rate of 3 °C / min, keep it at a constant temperature for 2 hours, and then cool it to room temperature to obtain a fluorine-doped IrO2 catalyst, labeled as F-IrO2-5.
[0071] Perform transmission electron microscopy analysis on the F-IrO2-5 catalyst of Example 5, and the results are as Figure 7 shown. It can be seen from the figure that the particle size of the F-IrO2-5 catalyst in Example 5 is uniform, about 1.6 - 2.6 nm.
[0072] Prepare a working electrode modified with the catalyst by the same method as in Example 1, and perform linear sweep voltammetry testing under a three-electrode system. The results show that the overpotential of the F-IrO2-5 catalyst is 263 mV at a current density of 10 mA / cm 2 and it exhibits better activity (355 mV) than the commercial IrO2-C catalyst.
[0073] Comparative Example 1
[0074] Weigh 5 g of urea and place it in a mortar, grind it into fine powder, and then place it in a crucible and calcine it in a muffle furnace. Heat it at a rate of 3 °C / min to 500 °C, maintain for 2 hours, and after cooling to room temperature, obtain a carbon nitride support.
[0075] After thoroughly grinding the above carbon nitride support, take 50 mg and disperse it in 25 mL of deionized water, and ultrasonicate for half an hour to obtain a uniform carbon nitride dispersion; at the same time, take 200 mg of iridium trichloride and dissolve it in 20 mL of deionized water, and ultrasonicate for 1 hour to completely dissolve it to obtain an IrCl3 precursor solution. Subsequently, take 1.94 mL of the IrCl3 precursor solution and add it to the above carbon nitride dispersion, continuously stir for 12 h, and then rotary evaporate at 55 °C to obtain a catalyst precursor powder.
[0076] Place the above powder in a quartz boat and calcine it in a muffle furnace. Heat it at a heating rate of 3 °C / min to 450 °C, keep the temperature constant for 2 hours, and after cooling to room temperature, obtain a fluorine-doped IrO2 catalyst, labeled as IrO2.
[0077] Perform transmission electron microscopy analysis on the IrO2 catalyst of Comparative Example 1, and the results are as Figure 8 shown. It can be seen from the figure that the IrO2 catalyst particles of Comparative Example 1 have uniform particle sizes, and the particle diameters are about 1.8 - 3 nm.
[0078] Prepare a working electrode modified with a catalyst by the same method as in Example 1, and perform linear sweep voltammetry testing under a three-electrode system. The results show that the overpotential of the IrO2 catalyst of the comparative example is 309 mV at a current density of 10 mA / cm 2 , showing better activity (355 mV) than the commercial IrO2-C catalyst.
[0079] The experimental results show that the fluorine doping strategy adopted in the present invention can significantly improve the intrinsic activity of iridium dioxide. The specific dopant and doping amount obtain better data effects, and the iridium dioxide catalysts prepared with less or excessive fluorine source doping amounts show poor performance in the oxygen evolution reaction.
[0080] Although the above embodiments have made a detailed description of the present invention, they are only a part of the embodiments of the present invention, not all embodiments. People can also obtain other embodiments according to these embodiments without creative work, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for preparing a fluorine-doped iridium oxide catalyst, characterized in that: The following steps are involved: 1) calcining a carbon nitride precursor to obtain a carbon nitride carrier, and dispersing the carbon nitride carrier in water to obtain a carbon nitride carrier dispersion; 2) mixing the carbon nitride carrier dispersion obtained in step 1) with an iridium salt solution and a fluorine source, and drying the mixture to obtain a catalyst precursor; 3) calcining the catalyst precursor obtained in step 2) to obtain a fluorine-doped iridium oxide catalyst.
2. The preparation method according to claim 1, characterized in that: In step 1), the carbon nitride precursor comprises one or more of urea, cyanamide, dicyandiamide and melamine; The calcination temperature is 500-550° C., the calcination time is 2 hours, and the heating rate is 3° C. / min.
3. The preparation method according to claim 1, characterized in that: The concentration of the carbon nitride carrier dispersion in step 1) is 2 mg / mL.
4. The preparation method according to claim 1, characterized in that: The iridium salt in the iridium salt solution in step 2) includes one or more of iridium trichloride, chloroiridic acid, sodium chloroiridate and iridium acetate; The concentration of the iridium salt solution is 10 mg / mL.
5. The preparation method according to claim 1, characterized in that: The fluorine source in step 2) includes one or more of ammonium fluoride, sodium fluoride and polyvinylidene fluoride.
6. The preparation method according to claim 1 or 4, characterized in that: In the step 2), the mass ratio of the volume of the carbon nitride carrier dispersion to the volume of the iridium salt solution and the fluorine source is 25 mL:1.94 mL:25-125 mg.
7. The preparation method according to claim 1, characterized in that: The drying conditions of step 2) include rotary evaporation drying or drying in an oven, and the drying temperature is 50-80°C.
8. The preparation method according to claim 1, characterized in that: The calcination conditions in step 3) include: temperature of 450° C., time of 2 h, and heating rate of 3° C. / min.
9. A fluorine-doped iridium oxide catalyst prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the fluorine-doped iridium oxide catalyst according to claim 9 in oxygen evolution reaction by water electrolysis.