Atomic-scale IrO2-supported electrolyzed water catalyst and preparation method and application thereof

Abstract

The invention discloses an atomic scale IrO2 supported electrolyzed water catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalyst preparation. The preparation method comprises the following steps: dissolving an iridium-based precursor in ultrapure water, and adding H2SO4 to obtain a mixed solution; then adding a manganese dioxide carrier, stirring and mixing; heating until the ligand exchange reaction is completed; and washing, drying and calcining. According to the present invention, the catalyst IrO2 is dispersed on the surface of the manganese dioxide carrier in the atomic scale, and the iridium loading amount is 2-8 wt.%, such that the loading amount of the noble metal iridium is substantially reduced; the catalyst is prepared by using a ligand exchange strategy, the process is simple, amplification is easy, excellent electro-catalytic performance is shown in electrolyzed water, and compared with IrO2 dispersed on the surface of manganese dioxide in the form of nanoparticles and IrO2 dispersed on the surface of manganese dioxide in the form of atoms, the catalyst can be utilized more efficiently.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation and electrocatalysis, and specifically relates to an atomic scale IrO2 supported water electrolysis catalyst and a preparation method and application thereof. Background Art

[0002] Against the background of the rapid development of hydrogen energy technology, proton exchange membrane water electrolysis technology (PEMWE) coupled with renewable energy is one of the most important ways to produce green hydrogen and is receiving widespread attention. However, the high cost issue has become the main obstacle to its widespread application. At present, the cost of green hydrogen production in my country is as high as 30 yuan / kg, far exceeding the 10 yuan / kg of gray hydrogen. Although the development of new energy technologies is expected to reduce the operating costs of PEMWE, the investment cost, especially the cost of proton exchange membrane electrolyzers, still has significant economies of scale. In large-scale production, the cost of catalysts (especially anode catalysts) has gradually become prominent and has become a key factor affecting the total cost of the electrolyzer. At present, the iridium loading used in the anode catalyst layer of the membrane electrode of the proton exchange membrane electrolyzer is about 2 mg / cm 2 If 1GW of proton exchange membrane electrolyzers are produced, the iridium consumption is about 1 ton. According to the current price of iridium in the futures market, the catalyst cost accounts for 30%-40% of the total cost of the electrolyzer. Therefore, on the basis of maintaining high current density and high electrolysis efficiency, it is necessary to optimize the anode catalyst layer and reduce the catalyst loading.

[0003] When the iridium loading of the anode catalyst layer decreases, the thickness of the catalyst layer decreases, the contact resistance between the diffusion layer and the catalyst layer increases, and the electrolysis efficiency decreases. Therefore, supported catalysts can effectively expose more active sites, reduce the stacking density of iridium, and increase the thickness of the catalyst layer, and have been widely studied by scholars at home and abroad. For example, a large number of literature reports on titanium dioxide-supported iridium dioxide catalysts as PEM water electrolysis anode catalysts, but the iridium dioxide loading is still as high as more than 45%. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present application provides an atomic-scale IrO2-supported water electrolysis catalyst and a preparation method and application thereof.

[0005] To solve the above problems, the present invention provides the following technical solutions:

[0006] In a first aspect, the present application provides an atomic-scale IrO2-supported water electrolysis catalyst, comprising a manganese dioxide carrier and IrO2 particles dispersed on its surface at the atomic scale.

[0007] In one embodiment of the present application, the Ir loading is 2 wt.%-8 wt.%.

[0008] In a second aspect, the present application provides a method for preparing an atomic-scale IrO2-supported water electrolysis catalyst, comprising the following steps:

[0009] S1. Dissolve the iridium-based precursor in ultrapure water, and add H2SO4 in proportion to obtain a mixed solution;

[0010] S2, adding the manganese dioxide carrier to the mixed solution prepared in step S1 in proportion, and stirring and mixing;

[0011] S3, heating until the ligand exchange reaction is completed;

[0012] S4. Wash, dry and calcine the product of step S3 to obtain an atomic-scale IrO2-supported water electrolysis catalyst. In one embodiment of the present application, the iridium-based precursor is selected from at least one of K2IrCl6, Na2IrCl6 and H2IrCl6.

[0013] In one embodiment of the present application, the molar ratio of the iridium-based precursor to H2SO4 is 1:2-3.

[0014] In one embodiment of the present application, the mass fraction of H2SO4 is 98.3%.

[0015] In one embodiment of the present application, the molar ratio of the iridium-based precursor to the manganese dioxide carrier is 1:20-80.

[0016] In one embodiment of the present application, a manganese dioxide carrier is added to the mixed solution obtained in step S1 in proportion, and the mixture is stirred and mixed for 1 hour.

[0017] In one embodiment of the present application, the heating temperature is 90-100° C., and the heating time is such that the color of the reaction solution changes from brown-red to colorless.

[0018] In one embodiment of the present application, the heating temperature is 95° C., and the heating time is when the color of the reaction solution changes from brown-red to colorless.

[0019] In one embodiment of the present application, the calcination temperature is 400-500° C., and the calcination time is 4-6 hours.

[0020] In one embodiment of the present application, the calcination temperature is 450° C. and the calcination time is 5 hours.

[0021] In a third aspect, the present application provides the application of atomic-scale IrO2-supported water electrolysis catalyst in PEM water electrolysis to produce hydrogen.

[0022] Compared with the prior art, the water catalyst provided by the present application has IrO2 dispersed on the surface of the manganese dioxide carrier at the atomic scale, and its iridium loading is adjustable within 2%-8%, which greatly reduces the loading of the precious metal iridium. The catalyst of the present application is prepared by using a ligand exchange strategy, with a simple process and easy to scale up. It exhibits excellent electrocatalytic performance in electrolysis of water. Compared with IrO2 dispersed on the surface of manganese dioxide as nanoparticles, IrO2 is dispersed on the surface of manganese dioxide at the atomic level, which can more efficiently utilize the catalyst and is superior to most current supported catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a high-angle annular dark field scanning projection (HAADF-STEM) image of the atomic-scale IrO2-supported water electrolysis catalyst prepared in Example 1 of the present invention;

[0024] Figure 2 The linear sweep voltammetry (LSV) graphs of different loadings of iridium dioxide dispersed in manganese dioxide carrier in alkaline medium;

[0025] Figure 3 This is the PEMWE performance diagram of the atomic-scale IrO2-supported water electrolysis catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The following will provide a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0027] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range.

[0028] Unless otherwise specified, the percentages between liquids and liquids in the present invention are volume / volume percentages; the percentages between liquids and solids in the present invention are volume / weight percentages; the percentages between solids and liquids in the present invention are weight / volume percentages; and the rest are weight / weight percentages.

[0029] Example 1

[0030] A method for preparing an atomic-scale IrO2-supported water electrolysis catalyst, specifically comprising:

[0031] (1) Dissolve 1.2 g of K2IrCl6 in 0.5 L of ultrapure water, and then add 0.49 g of 98.3% H2SO4;

[0032] (2) Add 5 g of manganese dioxide to step (1) and continue stirring for 1 h;

[0033] (3) heating the mixture in step (2) to 95° C., and when the color changes from brown-red to colorless, the ligand exchange reaction is complete;

[0034] (4) After washing and drying the product of step (3), calcining at 450° C. for 5 h, the prepared Ir loading is 8%.

[0035] like Figure 1 As shown, IrO2 is dispersed on the surface of the manganese dioxide support at the atomic scale.

[0036] Example 2

[0037] A method for preparing an atomic-scale IrO2-supported water electrolysis catalyst, specifically comprising:

[0038] (1) Dissolve 1.37 g of H2IrCl6 in 0.5 L of ultrapure water, and then add 0.7 g of 98.3% H2SO4;

[0039] (2) Add 7 g of manganese dioxide to step (1) and continue stirring for 1 h;

[0040] (3) heating the mixture in step (2) to 95° C., and when the color changes from brown-red to colorless, the ligand exchange reaction is complete;

[0041] (4) After washing and drying the product of step (3), calcining at 450° C. for 5 h, the prepared Ir loading was 6.4%.

[0042] Example 3

[0043] A method for preparing an atomic-scale IrO2-supported water electrolysis catalyst, specifically comprising:

[0044] (1) Dissolve 1.37 g of Na2IrCl6 in 0.5 L of ultrapure water, and then add 0.98 g of 98.3% H2SO4;

[0045] (2) Add 23 g of manganese dioxide to step (1) and continue stirring for 1 hour;

[0046] (3) heating the mixture in step (2) to 95° C., and when the color changes from brown-red to colorless, the ligand exchange reaction is complete;

[0047] (4) After washing and drying the product of step (3), calcining at 450° C. for 5 h, the prepared Ir loading is 2%.

[0048] First, the prepared catalyst was prepared into a slurry and tested in a three-electrode system. Figure 2 The linear voltammetric curves of 2% IrO2@MnO2, 4% IrO2@MnO2, 6% IrO2@MnO2 and 8% IrO2@MnO2 catalysts are shown at a current density of 10 mA / cm 2 When , the overpotentials are 338mV, 323mV, 320mV and 318mV, respectively, showing excellent electrocatalytic activity.

[0049] Then, the prepared catalyst (8% IrO2@MnO2) was ultrasonically sprayed onto the N115 membrane, with titanium felt as the anode diffusion layer and carbon paper as the cathode diffusion layer, and the electrolytic water performance was tested on a homemade fixture. 2 Down, Figure 3 The IV curve of PEMWE is shown, which can reach 2A / cm at 1.75V. 2 The current density shows excellent electrolytic performance.

[0050] The present application is described in detail above in conjunction with specific implementation methods and exemplary embodiments, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, the technical solution of the present application and its implementation methods may be subjected to a variety of equivalent substitutions, modifications or improvements, all of which fall within the scope of the present application.

Claims

1. An atomic scale IrO2 supported water electrolysis catalyst, characterized in that: It includes a manganese dioxide carrier and IrO2 particles dispersed on its surface at an atomic scale.

2. The atomic-scale IrO2-supported water electrolysis catalyst according to claim 1, characterized in that: The Ir loading is 2wt.%-8wt.%.

3. A method for preparing the atomic-scale IrO2-supported water electrolysis catalyst according to claim 1, characterized in that: The following steps are involved: S1. Dissolve the iridium-based precursor in ultrapure water, and add H2SO4 in proportion to obtain a mixed solution; S2, adding the manganese dioxide carrier to the mixed solution prepared in step S1 in proportion, and stirring and mixing; S3, heating until the ligand exchange reaction is completed; S4. Wash, dry and calcine the product of step S3 to obtain an atomic-scale IrO2-supported water electrolysis catalyst.

4. The method for preparing the atomic-scale IrO2 supported water electrolysis catalyst according to claim 3, characterized in that: The iridium-based precursor is selected from at least one of K2IrCl6, Na2IrCl6, and H2IrCl6.

5. The method for preparing the atomic-scale IrO2-supported water electrolysis catalyst according to claim 3, characterized in that: The molar ratio of the iridium-based precursor to the H2SO4 is 1:2-3.

6. The method for preparing the atomic-scale IrO2-supported water electrolysis catalyst according to claim 3, characterized in that: The molar ratio of the iridium-based precursor to the manganese dioxide carrier is 1:20-80.

7. The method for preparing the atomic-scale IrO2-supported water electrolysis catalyst according to claim 3, characterized in that: Add the manganese dioxide carrier to the mixed solution prepared in step S1 in proportion, and stir and mix for 1 hour.

8. The method for preparing the atomic-scale IrO2-supported water electrolysis catalyst according to claim 3, characterized in that: The heating temperature is 90-100°C, the calcination temperature is 400-500°C, and the calcination time is 4-6h.

9. The method for preparing the atomic-scale IrO2-supported water electrolysis catalyst according to claim 8, characterized in that: The heating temperature is 95°C, the calcination temperature is 450°C, and the calcination time is 5h.

10. Use of the atomic-scale IrO2-supported water electrolysis catalyst according to claim 1 or claim 2 in PEM water electrolysis to produce hydrogen.

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