A loadable IrRu alloy nanosheet catalyst and a preparation method thereof

Abstract

The application discloses a loadable IrRu alloy nanosheet catalyst and a preparation method thereof. The IrRu alloy nanosheet has a nanometer and / or sub-nanometer size thickness. The preparation method is simple in process and good in universality. According to the requirements of the application type of the catalyst, a targeted carrier can be selected. Metal precursors of hydrate iridium chloride and trichloro-ruthenium, a reducing agent and a carrier are fully mixed in an organic solvent. Under the reaction condition of heating and stirring, the IrRu alloy nanosheet can be controlled to grow on the surface of the carrier. The catalyst shows excellent electrocatalytic oxygen evolution reaction (OER) performance in an acidic and alkaline electrolyte, respectively.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanomaterial electrocatalysis, and particularly relates to a loadable IrRu alloy nanosheet catalyst and a preparation method thereof. BACKGROUND

[0002] Global energy crisis, environmental pollution and climate change seriously affect the sustainable development of human society. Developing and utilizing green and efficient clean energy is an effective way to alleviate the above problems. Hydrogen, as one of the most promising clean energy, can be produced in an environmentally friendly and high-purity way through electrochemical methods. Among them, the proton exchange membrane (PEM) water electrolysis hydrogen production technology has high operating current density, low energy consumption and high hydrogen production pressure, and is suitable for the fluctuating characteristics of renewable energy power generation and easy to combine with renewable energy consumption, which is a suitable solution for water electrolysis hydrogen production. PEM water electrolysis mainly includes two half reactions: anode oxygen evolution reaction (OER) and cathode hydrogen evolution reaction (HER). In acidic medium, the HER process of two-electron pathway at the cathode is relatively easy, and the required Pt catalyst can be reduced to 0.1 mg / cm 2 The anode OER involves multi-step proton and electron transfer, and its slow kinetics leads to the main efficiency loss of PEM water electrolysis (overpotential > 1.5 V, theoretical minimum value is 1.23 V). In addition, the rapid degradation of the anode catalyst in acidic and high oxidation environment also seriously hinders the development of PEM water electrolysis technology. Therefore, developing high-efficiency and durable OER catalysts under acidic conditions to reduce the overpotential and make the hydrogen production process more energy-saving has become a research difficulty in the field of water electrolysis technology.

[0003] At present, Ru-based and Ir-based materials have good OER catalytic performance in acidic medium. Ru has high catalytic activity, and Ir usually shows good catalytic stability. Based on the advantages of Ir and Ru two metals, designing and preparing IrRu alloy catalysts with high catalytic activity and stability has become a research hotspot in the development of water electrolysis technology in recent years. Considering that Ir and Ru are both noble metals, their reserves in the earth's crust are scarce, which leads to high cost of catalysts, hindering the large-scale preparation and application of IrRu catalysts. Therefore, designing and developing IrRu alloy catalysts with small size and large specific surface area is an effective way to reduce the cost of catalysts.

[0004] Catalytic materials with ultrathin two-dimensional structure can exhibit greater specific surface area and more abundant active sites, which have been proved to be ideal structures for designing advanced catalysts. However, due to the inherent atomic close-packed structure of noble metals, it is difficult for Ir, Ru and other metals to form ultrathin two-dimensional alloy materials. In addition, the surface energy of ultrathin two-dimensional nanomaterials is too high, which is easy to cause aggregation in the preparation process, resulting in coverage of active sites. Therefore, controlling the synthesis of ultrathin two-dimensional IrRu alloy nanomaterials with good dispersion is an effective way to realize high-performance OER catalysts. SUMMARY

[0005] To this end, the present application aims to provide a loadable IrRu alloy nanosheet catalyst and a preparation method thereof.

[0006] In one aspect, the present application provides a loadable IrRu alloy nanosheet catalyst, which comprises a carrier and IrRu alloy nanosheets loaded on the carrier, the thickness of the IrRu alloy nanosheets being 0.6-1.5 nm, and the molar ratio of Ir to Ru in the IrRu alloy nanosheets being 9:1-3:1.

[0007] It can be understood that the thickness of the IrRu alloy nanosheets in the range of 0.6-1.5 nm means that the thickness size of the IrRu alloy nanosheets has reached nanometer and / or sub-nanometer level.

[0008] Further, the above-mentioned carrier can be one-dimensional Pd nanowire, one-dimensional Au nanowire, one-dimensional Ag nanowire or one-dimensional carbon fiber, and two-dimensional graphene, etc.

[0009] In another aspect, the present application further provides a preparation method for preparing the above-mentioned loadable IrRu alloy nanosheet catalyst, the steps of which are specifically as follows:

[0010] (1) Preparation of metal precursor solution

[0011] Dissolve iridium hydrate chloride IrCl3·xH2O, ruthenium trichloride RuCl3 and a reducing agent in an organic solvent to prepare a metal precursor solution;

[0012] (2) Preparation of carrier solution

[0013] Dissolve the carrier in an organic solvent to prepare a carrier solution;

[0014] (3) Preparation of loadable IrRu alloy nanosheet catalyst

[0015] The metal precursor solution prepared in step (1) is mixed with the carrier solution prepared in step (2) to form a mixed solution at a volume ratio of 1:10-10:1, and the mixed solution is stirred at room temperature for 1-24 hours; then, the stirred mixed solution is transferred into a reaction container, and continues to be stirred at a reaction temperature of 60-200℃ for 1-24 hours, and then the heating and stirring are stopped, and after the mixed solution is cooled to room temperature, the mixed solution is subjected to centrifugal treatment at 4000-9000 r / min for 5 minutes, and then washed twice with an ethanol solution, so as to obtain a loadable IrRu alloy nanosheet catalyst.

[0016] The volume molar concentration ratio of the hydrated iridium chloride IrCl3·xH2O, the ruthenium trichloride RuCl3, the reducing agent and the carrier is 1-100:1-100:1-100:1-100.

[0017] The volume molar concentration ratio of 1-100:1-100:1-100:1-100 can be understood as follows: for example, when the volume molar concentration of the hydrated iridium chloride IrCl3·xH2O is selected as any value in the range of 1-100 mM, the volume molar concentrations of the ruthenium trichloride RuCl3, the reducing agent and the carrier should also be selected in the range of 1-100 mM.

[0018] The reducing agent in step (1) is at least one of citric acid, ascorbic acid, molybdenum carbonyl and glucose, and / or the carrier in step (2) is one of one-dimensional Pd nanowires, one-dimensional Au nanowires, one-dimensional Ag nanowires, one-dimensional carbon fibers and two-dimensional graphene, and / or the organic solvent in steps (1) and (2) is at least one of benzyl alcohol, ethanol, ethylene glycol, glyoxal and oleylamine.

[0019] In steps (1) and (2), ultrasonic dispersion can be used to promote dissolution.

[0020] In step (3), a thick-walled pressure-resistant reaction bottle can be used as the reaction container.

[0021] Especially, under the reaction conditions of heating and stirring in step (3), the IrRu alloy nanosheet can be controllably grown on the surface of the carrier.

[0022] Further, the application provides an application of the loadable IrRu alloy nanosheet catalyst in an electrocatalytic oxygen evolution reaction. The loadable IrRu alloy nanosheet catalyst exhibits excellent electrocatalytic oxygen evolution reaction (OER) performance in acidic and alkaline electrolytes, respectively.

[0023] Compared with the prior art, the application has the following advantages:

[0024] (1) The prepared loadable IrRu alloy nanosheet catalyst has good dispersity and ultra-thin (nanometer and / or sub-nanometer) size thickness, effectively improves the utilization rate of noble metal, and significantly reduces the cost of the catalyst.

[0025] (2) The preparation method has simple process and good universality, and according to the demand of the application type, a targeted carrier is selected for loading growth, so that the catalyst has a wider application range. BRIEF DESCRIPTION OF DRAWINGS

[0026] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which like reference numerals refer to like elements or elements in several views. The drawings are not necessarily to scale, the emphasis instead being placed upon illustrating the principles of the application. It should be understood that the drawings are merely meant to depict some embodiments of the application and to provide a further understanding of the application, which is not to be limited to the specific embodiments depicted in the drawings. In which:

[0027] Figure 1 The transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst prepared by the present application and loaded on Pd nanowires is shown in Figure 1, wherein, Figure 1 a is the low-magnification transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst loaded on Pd nanowires, Figure 1 b is the high-magnification transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst loaded on Pd nanowires;

[0028] Figure 2 The transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst prepared by the present application and loaded on Ag nanowires is shown in Figure 2, wherein, Figure 2 a is the low-magnification transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst loaded on Ag nanowires, Figure 2 b is the high-magnification transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst loaded on Ag nanowires;

[0029] Figure 3 The transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst prepared by the present application and loaded on carbon fibers is shown in Figure 3, wherein, Figure 3 a is the low-magnification transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst loaded on carbon fibers, Figure 3 b is the high-magnification transmission electron microscope (TEM) image of the IrRu alloy nanosheet catalyst loaded on carbon fibers;

[0030] Figure 4A transmission electron microscope (TEM) image of the graphene-supported IrRu alloy nanosheet catalyst prepared in the present application; wherein, Figure 4 In FIG. a, a low-magnification transmission electron microscope (TEM) image of the graphene-supported IrRu alloy nanosheet catalyst, Figure 4 In FIG. b, a high-magnification transmission electron microscope (TEM) image of the graphene-supported IrRu alloy nanosheet catalyst;

[0031] Figure 5 A performance curve of the loadable IrRu alloy nanosheet catalyst in an electrolyte in an electrocatalytic oxygen evolution reaction (OER) prepared in the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0033] Firstly, the present application provides a loadable IrRu alloy nanosheet catalyst, which comprises a carrier and IrRu alloy nanosheets supported on the carrier, the thickness of the IrRu alloy nanosheet is 0.6-1.5 nm, and the molar ratio of Ir to Ru in the IrRu alloy nanosheet is 9:1-3:1.

[0034] In the present application, the above carrier can be selected from one-dimensional Pd nanowires, Au nanowires, Ag nanowires or carbon fibers, and two-dimensional graphene, etc.

[0035] Specifically, Figures 1-4 The morphology characteristics of the IrRu alloy nanosheet catalyst when the carrier is Pd nanowires, Ag nanowires, carbon fibers and graphene, respectively, are shown in FIGS. 1-4, respectively. Figure 1 For example, from FIG. 1a, it can be clearly seen that the IrRu alloy nanosheet is grown on the surface of the carrier, and the overall structure of the catalyst is a one-dimensional structure, while Figure 1 FIG. 1b clearly shows that the IrRu alloy nanosheet in the catalyst has a nanometer / sub-nanometer size thickness, and the thickness is about 0.6-1.5 nm; and Figure 1 FIG. 2 shows that the overall structure of the catalyst is a two-dimensional structure, which is due to the use of two-dimensional graphene during preparation. Figure 4

[0036] Then, the present application provides a preparation method for preparing the above loadable IrRu alloy nanosheet catalyst, which uses a thick-walled pressure-resistant reaction bottle as a reaction container, and the specific process is as follows:

[0037] Example 1

[0038] ​(1) The hydrated iridium chloride IrCl3xH2O, ruthenium trichloride RuCl3, and ascorbic acid reducing agent are respectively dissolved in ethylene glycol solvent at a concentration of 20 mM, 1 mM, and 10 mM to prepare a metal precursor solution; preferably, ultrasonic dispersion can be performed to make it fully dissolved;

[0039] (2) The Pd nanowire carrier is dissolved in benzyl alcohol solvent at a concentration of 10 mM; preferably, ultrasonic dispersion can be performed to make it fully dissolved;

[0040] (3) The metal precursor solution prepared in the above step (1) and the carrier solution prepared in the above step (2) are mixed at a volume ratio of 1:10, stirred at room temperature for 10 h; then, the mixed solution is moved into a thick-walled pressure-resistant reaction bottle, stirred and heated at a reaction temperature of 80℃ for 24 h; after the reaction is completed, the heating and stirring are stopped; after the reaction solution is cooled to room temperature, it is subjected to centrifugal treatment at 9000 r / min for 5 min, and washed twice with ethanol solution, to prepare an IrRu alloy nanosheet catalyst supported on Pd nanowires.

[0041] Example Two

[0042] (1) The hydrated iridium chloride IrCl3xH2O, ruthenium trichloride RuCl3, and glucose reducing agent are respectively dissolved in ethylene glycol solvent at a concentration of 50 mM, 20 mM, and 100 mM to prepare a metal precursor solution; preferably, ultrasonic dispersion can be performed to make it fully dissolved;

[0043] (2) The Ag nanowire carrier is dissolved in ethanol solvent at a concentration of 50 mM; preferably, ultrasonic dispersion can be performed to make it fully dissolved;

[0044] (3) The metal precursor solution prepared in the above step (1) and the carrier solution prepared in the above step (2) are mixed at a volume ratio of 1:5, stirred at room temperature for 24 h; then, the mixed solution is moved into a thick-walled pressure-resistant reaction bottle, stirred and heated at a reaction temperature of 60℃ for 10 h; after the reaction is completed, the heating and stirring are stopped; after the reaction solution is cooled to room temperature, it is subjected to centrifugal treatment at 7500 r / min for 5 min, and washed twice with ethanol solution, to prepare an IrRu alloy nanosheet catalyst supported on Ag nanowires.

[0045] Example Three

[0046] (1) The hydrated iridium chloride IrCl3xH2O, ruthenium trichloride RuCl3, and citric acid reducing agent are respectively dissolved in ethylene glycol solvent at a concentration of 10 mM, 10 mM, and 20 mM to prepare a metal precursor solution; preferably, ultrasonic dispersion can be performed to make it fully dissolved;

[0047] (2) The Au nanowire carrier is dissolved in benzyl alcohol solvent at a concentration of 20 mM; preferably, ultrasonic dispersion is performed to fully dissolve it;

[0048] (3) The metal precursor solution prepared in step (1) above is mixed with the carrier solution prepared in step (2) above at a volume ratio of 1:1, and stirred at room temperature for 1 h; then, the mixed solution is moved into a thick-walled pressure-resistant reaction bottle, and stirred and heated at a reaction temperature of 150°C for 5 h; after the reaction is completed, heating and stirring are stopped; after the reaction solution is cooled to room temperature, centrifugal treatment is performed at 8000 r / min for 5 min, and ethanol solution is used to clean it twice, thereby preparing an IrRu alloy nanosheet catalyst supported on Au nanowires.

[0049] Example Four

[0050] (1) Iridium hydrate chloride IrCl3xH2O, ruthenium trichloride RuCl3, and ascorbic acid reducing agent are respectively dissolved in oleylamine solvent at concentrations of 1 mM, 5 mM, and 50 mM to prepare a metal precursor solution; preferably, ultrasonic dispersion is performed to fully dissolve it;

[0051] (2) The carbon fiber carrier is dissolved in oleylamine solvent at a concentration of 1 mM; preferably, ultrasonic dispersion is performed to fully dissolve it;

[0052] (3) The metal precursor solution prepared in step (1) above is mixed with the carrier solution prepared in step (2) above at a volume ratio of 5:1, and stirred at room temperature for 12 h; then, the mixed solution is moved into a thick-walled pressure-resistant reaction bottle, and stirred and heated at a reaction temperature of 200°C for 1 h; after the reaction is completed, heating and stirring are stopped; after the reaction solution is cooled to room temperature, centrifugal treatment is performed at 4000 r / min for 5 min, and ethanol solution is used to clean it twice, thereby preparing an IrRu alloy nanosheet catalyst supported on carbon fibers.

[0053] Example Five

[0054] (1) Iridium hydrate chloride IrCl3xH2O, ruthenium trichloride RuCl3, and carbonyl molybdenum reducing agent are respectively dissolved in glyoxal solvent at concentrations of 100 mM, 100 mM, and 1 mM to prepare a metal precursor solution; preferably, ultrasonic dispersion is performed to fully dissolve it;

[0055] (2) The graphene carrier is dissolved in ethylene glycol solvent at a concentration of 100 mM; preferably, ultrasonic dispersion is performed to fully dissolve it;

[0056] (3) The metal precursor solution prepared in step (1) and the carrier solution prepared in step (2) are mixed at a volume ratio of 10:1 and stirred at room temperature for 5 hours. Then, the mixed solution is transferred into a thick-walled pressure-resistant reaction flask and stirred and heated at a reaction temperature of 100°C for 12 hours. After the reaction is completed, the heating and stirring are stopped. After the reaction solution is cooled to room temperature, it is centrifuged at 5000 r / min for 5 minutes and washed twice with ethanol solution. The IrRu alloy nanosheet catalyst supported on graphene is prepared.

[0057] The preparation method provided by this invention is simple, has good versatility, and can select a specific support for loading and growth according to the requirements of the catalyst application type. Under the reaction conditions of heating and stirring, IrRu alloy nanosheets can be grown in a controlled manner on the surface of the support.

[0058] Furthermore, the present invention provides an application of the above-mentioned supported IrRu alloy nanosheet catalyst in the electrocatalytic oxygen evolution reaction.

[0059] In this embodiment, the electrolytes were selected as 0.5 M H2SO4 solution and 1 M KOH solution, respectively. In both electrolytes, the supported IrRu alloy nanosheet catalyst of the present invention exhibited excellent electrocatalytic oxygen evolution reaction (OER) performance.

[0060] in, Figure 5 This invention demonstrates the electrocatalytic oxygen evolution reaction (OER) performance of the supported IrRu alloy nanosheet catalyst in acidic and alkaline electrolytes. Taking the IrRu alloy nanosheet catalyst supported on Pd nanowires as an example, in a 0.5 M H₂SO₄ electrolyte (…),… Figure 5 In (a) and 1M KOH electrolyte ( Figure 5 (b) The catalyst's catalytic overpotentials for OER are 215 mV and 230 mV, respectively, which are 159 mV and 126 mV lower than those of known commercial IrO2 catalysts, and 127 mV and 95 mV lower than those of known commercial RuO2 catalysts. Regarding catalytic stability... Figure 5 (c and d), the catalyst under constant current (10 mA cm⁻¹) -2 Under these conditions, the catalyst can maintain a low catalytic overpotential for 48 hours in both acidic and alkaline electrolytes, while known commercial IrO2 catalysts or known commercial RuO2 catalysts deactivate within a few hours. In comparison, the catalyst of this invention has a significant advantage in catalytic OER stability.

[0061] In addition, it is worth mentioning that the loadable IrRu alloy nanosheet catalysts of the application can also exhibit excellent electrocatalytic oxygen evolution reaction (OER) activity and stability in an acidic membrane electrode assembly.

[0062] Although the embodiments of the application have been shown and described above, it should be understood by those skilled in the art that the above embodiments are exemplary and should not be construed as limiting the application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments without departing from the principles and purposes of the application within the scope of the application.

Claims

1. A preparation method for preparing a loadable IrRu alloy nanosheet catalyst for electrocatalytic oxygen evolution reaction, characterized in that, The loadable IrRu alloy nanosheet catalyst comprises a carrier and IrRu alloy nanosheets loaded on the carrier; the thickness of the IrRu alloy nanosheets is 0.6-1.5 nm, and the molar ratio of Ir to Ru in the IrRu alloy nanosheets is 9:1-3:1; the carrier is one-dimensional Pd nanowires, one-dimensional Au nanowires, one-dimensional Ag nanowires or one-dimensional carbon fibers, wherein the preparation method comprises the following steps: (1) Preparation of a metal precursor solution Dissolve hydrated iridium chloride IrCl3·xH2O, ruthenium trichloride RuCl3 and a reducing agent in an organic solvent to prepare the metal precursor solution; wherein the reducing agent is citric acid, ascorbic acid, molybdenum carbonyl or glucose; (2) Preparation of a carrier solution Dissolve the carrier in an organic solvent to prepare the carrier solution; (3) Preparation of a loadable IrRu alloy nanosheet catalyst Mix the metal precursor solution prepared in the above step (1) and the carrier solution prepared in the above step (2) in a volume ratio of 1:10-10:1 to form a mixed solution, and stir the mixed solution at room temperature for 1-24 h; then, move the stirred mixed solution into a reaction container, continue to stir under heating at a reaction temperature of 60-200 ℃ for 1-24 h, then stop heating and stirring, and after the mixed solution is cooled to room temperature, subject it to centrifugal treatment at 4000-9000 r / min for 5 min, then wash it twice with an ethanol solution, and the loadable IrRu alloy nanosheet catalyst is obtained; Wherein, the volume molar concentration ratio of the hydrated iridium chloride IrCl3·xH2O, ruthenium trichloride RuCl3, reducing agent and carrier is 1-100:1-100:1-100:1-100.

2. The production method according to claim 1, characterized by, In the above steps (1) and (2), the organic solvent is benzyl alcohol, ethanol, ethylene glycol, glyoxal or oleylamine.

3. The production method according to any one of claims 1 to 2, characterized by, In the above steps (1) and (2), ultrasonic dispersion is used to promote dissolution during preparation.

4. The production method according to any one of claims 1 to 2, characterized by, In the above step (3), the reaction container is a thick-walled pressure-resistant reaction bottle.

5. Application of the loadable IrRu alloy nanosheet catalyst prepared based on the preparation method of any one of claims 1-4 in an electrocatalytic oxygen evolution reaction.

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