A catalyst for hydrogen production by proton exchange membrane electrolysis and a method for preparing the same

Abstract

The application discloses a kind of proton exchange membrane hydrogen production electrolysis catalyst and its preparation method, its preparation method includes the following steps: S1, iridium precursor salt and ruthenium precursor salt are dissolved in water, obtain solution A;S2, triblock copolymer P123 is dissolved in ethanol, obtain solution B;S3, potassium iodide is dissolved in water, obtain solution C;S4, the solution A, solution B and solution C are uniformly mixed and then transferred to reaction kettle, heated and reacted;S5, the product obtained in the step S4 is collected, and the iridium ruthenium alloy catalyst is obtained by centrifugation and washing.The solvent hot reduction method is used in the application, the triblock copolymer P123 is used as reducing agent and protective agent, ethanol is used as solvent, and potassium iodide is added to improve the catalyst size and crystallization degree, so that the iridium ruthenium alloy catalyst with high catalytic activity and high stability is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysis technology, in particular to a kind of proton exchange membrane hydrogen production electrolysis catalyst and preparation method thereof. BACKGROUND

[0002] Proton exchange membrane (PEM) water electrolysis hydrogen production is a kind of efficient, green hydrogen production technology, with high energy conversion efficiency, fast response and small footprint advantage.The working principle is that water molecules are decomposed into oxygen and hydrogen ions under the action of anode catalyst, and hydrogen ions move to the cathode through the proton exchange membrane, and hydrogen is generated under the action of cathode catalyst.

[0003] Noble metal iridium (Ir) and ruthenium (Ru) based material is commonly used PEM water electrolysis hydrogen production anode electrocatalyst, and alloy catalyst can enhance catalytic activity by the synergistic effect between metals.The existing technology is prepared by hydrothermal method to prepare iridium ruthenium alloy catalyst, and the obtained alloy catalyst is mostly amorphous nanoparticles, and the particle size is generally about 2nm, and the overall structure has low crystallinity;And the morphology of the catalyst generally has the problems of low electrocatalytic activity and poor stability. SUMMARY

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is how to improve the electrocatalytic activity and stability of iridium ruthenium alloy catalyst.

[0005] To solve the above technical problems, the first aspect of the present application provides a preparation method of a proton exchange membrane hydrogen production electrolysis catalyst, comprising the following steps:

[0006] S1, dissolve iridium precursor salt and ruthenium precursor salt in water to obtain solution A;

[0007] S2, dissolve triblock copolymer P123 in ethanol to obtain solution B;

[0008] S3, dissolve potassium iodide in water to obtain solution C;

[0009] S4, mix the solution A, solution B and solution C uniformly, then transfer to a reaction kettle, heat and react;

[0010] S5, collect the product obtained in step S4, centrifuge and wash to obtain iridium ruthenium alloy catalyst.

[0011] The present application adopts solvent thermal reduction method, uses triblock copolymer P123 as reducing agent and protective agent, ethanol as solvent, and adds potassium iodide to improve the size and crystallinity of the catalyst, so as to obtain iridium ruthenium alloy catalyst with high catalytic activity and high stability.

[0012] Further, in the step S4, the ratio of the sum of the amount of substance of the iridium precursor salt and the ruthenium precursor salt to the amount of substance of potassium iodide in the mixed solution of the solution A, the solution B and the solution C is 1:0.1-3. The addition of the appropriate amount of potassium iodide can adjust the structure and surface composition of the iridium-ruthenium alloy system catalyst, so that the originally poor crystallinity of iridium and ruthenium becomes an alloy with higher crystallinity and high-index crystal surface exposure.

[0013] Further, in the step S4, the ratio of the sum of the amount of substance of the iridium precursor salt and the ruthenium precursor salt to the amount of substance of the triblock copolymer P123 in the mixed solution of the solution A, the solution B and the solution C is 1:2-10.

[0014] Further, in the step S3, the mass concentration of potassium iodide in the solution C is 0.04-0.4 g / mL.

[0015] Further, in the step S1, the mass concentration of the iridium precursor salt in the solution A is 0.001-0.005 g / mL, and the mass concentration of the ruthenium precursor salt is 0.001-0.003 g / mL.

[0016] Further, in the step S1, the iridium precursor salt is selected from one or more than two combinations of iridium trichloride, iridium tetrachloride, chloro iridic acid, iridium acetate, ammonium chloro iridic acid and potassium hexachloroiridate; and the ruthenium precursor salt is selected from one or more than two combinations of ruthenium trichloride, ruthenium tetrachloride, ruthenium acetylacetone and ammonium hexachlororuthenate.

[0017] Further, in the step S2, the concentration of the triblock copolymer P123 in the solution B is 0.1-1.0 mol / L.

[0018] Further, in the step S4, the reaction temperature is 100-240 DEG C, and the reaction time is 4-24 h.

[0019] The second aspect of the application provides a catalyst for hydrogen production by proton exchange membrane electrolysis, which is prepared by the above preparation method. The catalyst synthesized by the application has excellent electrocatalytic OER performance and has a good application and development prospect in a PEM electrolytic cell.

[0020] Further, the catalyst is a core-shell structure nanoparticle with a size of 100-600 nm, and the catalyst with such a morphology has excellent stability.

[0021] In summary, compared with the prior art, the application has the following beneficial effects:

[0022] (1) The iridium-ruthenium alloy catalyst is prepared by the solvothermal method in the application, which can effectively improve the reduction efficiency and degree of difficult-to-reduce metal precursors compared with the hydrothermal method.

[0023] (2) The KI halogen small molecule is added in the catalyst synthesis system, so that the crystallinity of the synthesized IrRu nanoparticles is significantly improved, and according to the different addition amount, large-scale yolk-shell structures can be self-assembled, and excellent stability is shown.

[0024] (3) The KI halogen molecule is added, so that the iodine ions in the solvent control the generation of high-index crystal faces in the nanoparticle growth process, and the catalytic activity of the catalyst is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a TEM diagram of the iridium-ruthenium alloy catalyst of Example 1 of the present application.

[0026] Figure 2 is a TEM diagram of the iridium-ruthenium alloy catalyst of Comparative Example 1 of the present application.

[0027] Figure 3 is an XRD diagram of the iridium-ruthenium alloy catalyst of Example 1 and Comparative Example 1 of the present application.

[0028] Figure 4 is an LSV curve diagram of the catalyst of the present application and the comparative example in 0.5M H2SO4.

[0029] Figure 5 is a stability test comparison diagram of the catalyst of the present application and the comparative example. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings.

[0031] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value in the stated range and any other stated value or intermediate value in the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0032] Many modifications and changes can be made to the specific embodiments of the present application without departing from the scope or spirit of the present application, which will be apparent to those skilled in the art. Other embodiments obtained from the specification of the present application will be apparent to those skilled in the art. The specification and examples of the present application are only exemplary.

[0033] The embodiment of the present application provides a hydrogen production catalyst for proton exchange membrane electrolysis and a preparation method thereof, an iridium-ruthenium alloy catalyst is prepared by a solvothermal reduction method, a triblock copolymer P123 is used as a reducing agent and a protective agent, and ethanol is used as a solvent; and potassium iodide is added to control the size and crystallinity of the catalyst. The preparation method specifically comprises the following steps:

[0034] S1, a certain amount of iridium precursor salt and ruthenium precursor salt is dissolved in water, and ultrasonic is applied until complete dissolution to obtain a deep red-brown solution A. In specific embodiments, the mass concentration of the iridium precursor salt in the solution A is 0.001-0.005 g / mL, and the mass concentration of the ruthenium precursor salt is 0.001-0.003 g / mL. The iridium precursor salt can be selected from iridium trichloride, iridium tetrachloride, chloroiridic acid, iridium acetate, ammonium chloroiridate, potassium hexachloroiridate, etc., and the ruthenium precursor salt can be selected from ruthenium trichloride, ruthenium tetrachloride, ruthenium acetylacetone, ammonium hexachlororuthenate, etc.

[0035] S2, a certain amount of triblock copolymer P123 is dissolved in ethanol, and ultrasonic is applied until complete dissolution to obtain a colorless transparent solution B. In specific embodiments, the concentration of the triblock copolymer P123 in the solution B is 0.1-1.0 mol / L.

[0036] S3, a certain amount of potassium iodide is dissolved in water, and ultrasonic is applied until complete dissolution to obtain a colorless transparent solution C. In specific embodiments, the mass concentration of the potassium iodide in the solution C is 0.04-0.4 g / mL.

[0037] S4, after the solution A, the solution B and the solution C are uniformly mixed, they are transferred to a reaction kettle, and heating is performed to react, and the reaction conditions are as follows: the reaction temperature is 100-240 DEG C, and the reaction time is 4-24 h. In specific embodiments, the ratio of the total amount of substance of the iridium precursor salt and the ruthenium precursor salt, the amount of substance of the triblock copolymer P123 and the amount of substance of the potassium iodide in the mixed solution is 1:2-10:0.1-3.

[0038] S5, the product obtained in step S4 is collected, and centrifugation and washing are performed to obtain an iridium-ruthenium alloy catalyst.

[0039] The above preparation method adds an appropriate amount of KI in the reaction process, which can adjust the structure and surface composition of the IrRu system catalyst, so that the originally poor crystallinity of Ir and Ru becomes an alloy with higher crystallinity and higher activity of exposed static crystal face, and the catalyst is easier to self-assemble into a large-scale yolk-shell structure, thereby improving the stability.

[0040] In specific embodiments, the nanoparticle size of the iridium-ruthenium alloy catalyst reaches 100-600 nm, and exposes a high-index {200} crystal face. The iridium-ruthenium alloy catalyst has excellent electrocatalytic OER performance, and has a good application and development prospect in a PEM electrolytic cell.

[0041] The technical effects of the present application are described below in connection with specific examples. Unless otherwise specified, the raw materials in the examples of the present application are purchased through commercial channels. Example

[0042] The iridium-ruthenium alloy catalyst was prepared as follows:

[0043] (1) 0.0090 g IrCl3and 0.0062 g RuCl3were dissolved in 600 uL deionized water, and ultrasonic stirring was used to dissolve the solution to obtain solution A.

[0044] (2) 1.003 g P123 was added to 60 mL ethanol, and ultrasonic stirring was used to completely dissolve the solution to obtain solution B.

[0045] (3) 0.08 g KI was dissolved in 1 mL deionized water, and ultrasonic stirring was used to dissolve the solution to obtain solution C.

[0046] (4) After solution A, B and C were mixed uniformly, they were transferred to a hydrothermal reactor, and reacted at 180°C for 12 h.

[0047] (5) After centrifugation and washing, the product was obtained as an iridium-ruthenium alloy catalyst, labeled as IrRu-KI. Example

[0048] The iridium-ruthenium alloy catalyst was prepared as follows:

[0049] (1) 0.010 g (NH4)2IrCl6and 0.008 g RuCl4were dissolved in 600 uL deionized water, and ultrasonic stirring was used to dissolve the solution to obtain solution A.

[0050] (2) 1 g P123 was added to 60 mL ethanol, and ultrasonic stirring was used to completely dissolve the solution to obtain solution B.

[0051] (3) 0.1 g KI was dissolved in 1 mL deionized water, and ultrasonic stirring was used to dissolve the solution to obtain solution C.

[0052] (4) After solution A, B and C were mixed uniformly, they were transferred to a hydrothermal reactor, and reacted at 150°C for 16 h.

[0053] (5) After centrifugation and washing, the product was obtained as an iridium-ruthenium alloy catalyst.

[0054] Comparative Example 1

[0055] The iridium-ruthenium alloy catalyst was prepared as follows:

[0056] (1) 0.0090 g IrCl3 and 0.0062 g RuCl3 were dissolved in 600 uL deionized water, and the solution was dissolved by ultrasonic stirring to obtain solution A.

[0057] (2) 1.003 g P123 was added to 60 mL ethanol, and the solution was completely dissolved by ultrasonic stirring to obtain solution B.

[0058] (3) After mixing solution A and B uniformly, the mixture was transferred to a hydrothermal reactor, and reacted at 180℃ for 12 h.

[0059] (5) After centrifugation and washing, the product was obtained as an iridium-ruthenium alloy catalyst, marked as IrRu.

[0060] The TEM of the iridium-ruthenium alloy catalyst prepared in Example 1 and Comparative Example 1 is shown in Figure 1 and Figure 2 respectively, and it can be seen from Figure 2 (a) that the amorphous agglomerates of the IrRu catalyst are composed of small-scale particles, and there is an obvious interface between the small particles; Figure 2 (b) that the size of the catalyst particles is about 2 nm; and from Figure 2 (c) that the exposed crystal face of the alloy is {111}. Figure 1 (a) it can be seen that the IrRu-KI catalyst prepared in Example 1 forms a larger-scale yolk-shell structure with a size of about 300-400 nm; from Figure 1 (b) it can be seen that the small particles in Figure 2 (b) form a higher degree of crystallization, and the crystal lattice fringes are more obvious; and from Figure 1 (c) it can be seen that the crystal lattice fringes in the IrRu-KI catalyst are in the form of {200} crystal face, indicating that the prepared iridium-ruthenium alloy has a high-index crystal face exposed.

[0061] The XRD of the iridium-ruthenium alloy catalyst prepared in Example 1 and Comparative Example 1 is shown in Figure 3 , indicating that the IrRu catalyst forms an alloy with a face-centered cubic (fcc) structure of Ir, and since Ir is the main structure, it conforms to the standard PDF card. Compared with the IrRu catalyst, the IrRu-KI catalyst starts to have a more obvious diffraction peak of the {200} crystal face in the XRD diffraction characterization, further confirming that the IrRu alloy regulated by KI has a high-index {200} crystal face.

[0062] Comparative Example 2

[0063] Commercial RuO2 catalyst.

[0064] Experimental Example 1

[0065] A three-electrode system was constructed: the IrRu-KI catalyst prepared in Example 1, the IrRu catalyst prepared in Comparative Example 1, and the commercial RuO2 catalyst in Comparative Example 2 were used as working electrodes, respectively. A platinum sheet was used as the counter electrode, and a silver chloride electrode was used as the reference electrode. A 0.5 M H2SO4 solution was used as the electrolyte, and the cathode cell and anode cell were separated by an ion exchange membrane.

[0066] LSV curves were obtained using a linear scan method on an electrochemical workstation. The test results are as follows: Figure 4 As shown in the figure, the catalytic activity of the IrRu catalyst is significantly improved compared to commercial RuO2, while the IrRu-KI catalyst further enhances the OER catalytic activity. (At 10 mA·cm⁻¹) -2 The over-potentials at the current densities are IrRu-KI (190mV), IrRu (228mV), and RuO2 (270mV), respectively.

[0067] Experiment Example 2

[0068] The stability of the IrRu-KI catalyst prepared in Example 1, the IrRu catalyst prepared in Comparative Example 1, and the commercial RuO2 catalyst in Comparative Example 2 were tested, and the results are as follows: Figure 5 As shown in the figure. It can be seen from the figure that the commercial RuO2 catalyst at 10 mA·cm⁻¹... -2 Under current density, the OER test results showed that the catalyst deactivated in less than 20 hours, with a sharp increase in potential. In contrast, the IrRu catalyst exhibited relatively stable performance, but its overpotential exceeded 330 mV after approximately 280 hours of testing. Meanwhile, IrRu-KI maintained stable performance at an overpotential of 280 mV throughout the 500-hour test, without significant increase.

[0069] The above experimental results show that without the addition of KI, due to Ir 3+ Ir and Ru metals are difficult to reduce, have a slow reduction rate, and readily form nanoparticles of about 2 nm in size, exposing the basic {111} crystal plane, which then aggregate to form an amorphous structure. However, after adding KI, Ir... - Ions can selectively adsorb on the {200} crystal plane of the IrRu alloy, which leads to a higher selective exposure of the {200} crystal plane in the IrRu alloy. The resulting IrRu-KI alloy structure has a higher degree of crystallinity and is more likely to self-assemble into a yolk core-shell structure, thereby improving stability.

[0070] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. A method for producing a catalyst for hydrogen production by proton exchange membrane electrolysis, characterized by, The method comprises the following steps: S1, dissolving iridium precursor salt and ruthenium precursor salt in water to obtain solution A; S2, dissolving triblock copolymer P123 in ethanol to obtain solution B; S3, dissolving potassium iodide in water to obtain solution C; S4, uniformly mixing solution A, solution B and solution C, the ratio of the total amount of substance of iridium precursor salt and ruthenium precursor salt to the amount of substance of potassium iodide in the mixed solution is 1:0.1-3, and the ratio of the amount of substance of triblock copolymer P123 to the amount of substance of potassium iodide is 1:2-10, and the mixed solution is transferred to a reaction kettle for heating reaction; S5, collecting the product obtained in step S4, and centrifuging and washing to obtain an iridium-ruthenium alloy catalyst with a core-shell structure, a size of 100-600 nm, and a high-index {200} crystal plane exposed.

2. The method for producing a catalyst for hydrogen production by means of a proton exchange membrane electrolysis according to claim 1, characterized by, In the step S3, the mass concentration of potassium iodide in the solution C is 0.04-0.4 g / mL.

3. The method for preparing a catalyst for hydrogen production by proton exchange membrane electrolysis according to claim 1, characterized by, In the step S1, the mass concentration of iridium precursor salt in the solution A is 0.001-0.005 g / mL, and the mass concentration of ruthenium precursor salt is 0.001-0.003 g / mL.

4. The method for producing a catalyst for hydrogen production by means of a proton exchange membrane electrolysis according to claim 3, characterized in that, In the step S1, the iridium precursor salt is selected from one or more than two combinations of iridium trichloride, iridium tetrachloride, chloro iridic acid, iridium acetate, ammonium chloro iridic acid and potassium hexachloroiridate; and the ruthenium precursor salt is selected from one or more than two combinations of ruthenium trichloride, ruthenium tetrachloride, ruthenium acetylacetone and ammonium hexachlororuthenate.

5. The method for preparing a catalyst for hydrogen production by proton exchange membrane electrolysis according to claim 1, characterized by, In the step S2, the concentration of triblock copolymer P123 in the solution B is 0.1-1.0 mol / L.

6. The method for preparing a catalyst for hydrogen production by proton exchange membrane electrolysis according to claim 1, characterized by, In the step S4, the reaction temperature is 100-240℃, and the reaction time is 4-24 h.

7. A catalyst for proton exchange membrane hydrogen electrolysis, characterized in that, Prepared by the preparation method of any one of claims 1-6.

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