Low-load noble metal catalyst for industrial water electrolysis and preparation method of low-load noble metal catalyst

Abstract

The invention relates to the technical field of catalysts, and particularly provides a low-load noble metal catalyst for industrial water electrolysis and a preparation method thereof. According to the preparation method, thin-layer two-dimensional layered double hydroxide (LDH) is used as a substrate material, a hydrothermal reaction is performed at a certain temperature and pressure to load noble metals (Ru, Rh, Pd, Ag, Ir, Pt, Au and the like), then washing, impurity ion removal and drying are performed to obtain a target product, the obtained electrocatalyst is ultralow-loading noble metal loaded LDH, the loading amount of the noble metals accounts for 0.1 wt%-0.5 wt%, and the loading amount of the noble metals accounts for 0.1 wt%-0.5 wt%. The prepared electrocatalyst can realize efficient and stable water decomposition with industrial-grade current density. The obtained electrocatalyst has high catalytic activity and durability under industrial conditions; and the preparation process is simple to operate and good in repeatability, and the loading capacity of the noble metal is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and in particular to a low-loaded noble metal catalyst for industrial water electrolysis and a preparation method thereof. Background Art

[0002] Hydrogen fuel has the advantages of high calorific value (143MJ·Kg-1) and zero carbon pollution. It is currently the most promising energy carrier, which is expected to reduce or even get rid of dependence on traditional fossil energy and innovate the current energy structure. Water electrolysis is the most efficient and sustainable technology for producing hydrogen, and water electrolysis technology has begun to gradually transition from the laboratory to industrialization, which requires electrocatalysts to operate stably under industrial conditions and have low prices. Traditional precious metal catalysts, including Pt / C and RuO2 / IrO2, require more energy consumption due to their slow kinetics and short-term long-cycle durability. Scarce resources and high prices restrict large-scale applications. This requires us to develop low-load precious metal catalysts suitable for industrial conditions, with both low prices and long-term long-cycle durability. Summary of the invention

[0003] In view of this, the present invention proposes a low-loaded precious metal catalyst for industrial water electrolysis and a preparation method thereof. The electrocatalyst has high catalytic activity and durability under industrial conditions; and the preparation process is simple to operate, has good repeatability, and greatly reduces the cost of the catalyst.

[0004] The technical solution of the present invention is implemented as follows: The present invention provides a low-loaded precious metal catalyst for industrial water electrolysis, wherein the catalyst uses a thin layer of two-dimensional LDH as a base material and is loaded with an ultra-low load of precious metals.

[0005] Among various two-dimensional substrate materials, LDH has the advantages of large specific surface area, easily adjustable components and interlayer ions, and abundant defective loading sites, which provide favorable conditions for the loading of low-load precious metals. At the same time, it can be expanded to different LDH materials, such as NiCr-LDH, NiFe-LDH, NiCo-LDH and NiMn-LDH. After ultra-low-load precious metals are loaded on the two-dimensional LDH substrate, they are anchored on the substrate through covalent action to achieve spatial dispersion, avoiding particle agglomeration caused by dynamic evolution after applying bias voltage, which affects the activity and durability of the catalyst. The construction of LDH catalysts loaded with ultra-low precious metals can greatly reduce the cost of industrial-scale applications and achieve high activity and long-lasting durability under industrial conditions.

[0006] In some embodiments, the thin-layer two-dimensional LDH includes one or more of NiCr-LDH, NiFe-LDH, NiCo-LDH, CoFe-LDH, and NiMn-LDH.

[0007] In some embodiments, the noble metal includes one or more of Ru, Rh, Pd, Ag, Ir, Pt, and Au.

[0008] In some embodiments, the loading amount of the noble metal is 0.1 wt%-0.5 wt% of the substrate material.

[0009] In a second aspect, the present invention further provides a method for preparing the low-loaded precious metal catalyst for industrial water electrolysis, comprising the following steps: (1) mixing the first precursor compound of the LDH substrate material and the second precursor compound in water, and ultrasonically treating at room temperature for 1-6 hours; (2) stirring the mixture after ultrasonic treatment in step (1) with RuCl3 at 20-30°C for 1-3h; (3) mixing the solution stirred in step (2) with the pretreated nickel foam, and then hydrothermally preserving the mixture at 100-200° C. for 8-16 hours; (4) Washing the sample after the hydrothermal treatment in step (3) to remove excess impurities, and drying to obtain a LDH thin layer two-position nanosheet catalyst loaded with precious metals.

[0010] In some embodiments, the first precursor compound of the LDH substrate material in step (1) is a nickel-containing compound, and the second precursor compound is one of a chromium-containing compound, an iron-containing compound, a cobalt-containing compound, and a manganese-containing compound.

[0011] In some embodiments, the nickel-containing compound is one or more of nickel nitrate, nickel carbonate, nickel acetate, and nickel chloride; the chromium-containing compound is one or more of chromium nitrate, chromium carbonate, chromium acetate, and chromium chloride; the iron-containing compound is one or more of iron nitrate, iron carbonate, iron acetate, and iron chloride; the cobalt-containing compound is one or more of cobalt nitrate, cobalt carbonate, cobalt acetate, and cobalt chloride; and the manganese-containing compound is one or more of manganese nitrate, manganese carbonate, manganese acetate, and manganese chloride.

[0012] In some embodiments, in step (1), the molar ratio of the first compound to the second precursor compound is 1:(1-4).

[0013] In some embodiments, the size of the LDH thin-layer two-dimensional nanosheet catalyst loaded with precious metals obtained in step (4) is 100-800 nm.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a low-loaded precious metal catalyst for industrial water electrolysis. The catalyst is a low-loaded precious metal-loaded LDH. The thin-layer two-dimensional nanosheet material has a large specific surface area, which increases the contact area with the electrolyte and accelerates the electron transfer and mass transfer process. The Ru / NiCr-LDH material prepared by the present invention can achieve high catalytic activity and long-lasting durability under industrial conditions. Moreover, the preparation process of the present invention is simple to operate and the reaction conditions are mild, which greatly reduces the industrialization cost of the catalyst application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 This is the SEM spectrum of the Ru / NiFe-LDH material prepared in Example 1 of the present invention; Figure 2 This is the EXAFS spectrum of the Ru / NiFe-LDH material prepared in Example 1 of the present invention; Figure 3 HER LSV of Ru / NiCr-LDH and 20 wt% Pt / C, and OER LSV of Ru / NiCr-LDH and RuO2 prepared in Example 2 of the present invention; Figure 4 This is a polarization curve diagram of the electrolytic cell assembled with Ru / NiCr-LDH prepared in Example 2 of the present invention; Figure 5 This is a durability spectrum of the Ir / NiCr-LDH prepared in Example 3 of the present invention when operated under industrial conditions. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0019] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0020] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0021] Example 1 This embodiment provides a method for preparing a low-loaded precious metal catalyst for industrial water electrolysis, comprising the following steps: Weigh 0.3 mmol nickel chloride hexahydrate and 0.3 mmol ferric chloride hexahydrate respectively and transfer them to a 100 mL glass beaker, add 20 mL distilled water, and ultrasonically treat for 1 hour to obtain a uniform mixed solution. Then add 0.05 mmol ruthenium chloride hydrate to the uniform solution, and stir magnetically at 20℃ for 2 hours to obtain a uniform mixed solution. Soak the nickel foam in 1.0 M hydrochloric acid solution to remove impurities and oxides on the surface, take out the nickel foam, rinse it with distilled water and anhydrous ethanol three times in sequence, and place it in a vacuum drying oven at 60℃ for 10 hours. Add the acid-treated nickel foam to the above uniform solution, heat it to 150℃ at a rate of 5℃ / min, and hydrothermally react for 12 hours. After cooling to room temperature, take out the catalyst, rinse it with distilled water and anhydrous ethanol three times in sequence, and vacuum dry it at 60℃ for 10 hours to obtain 1.01g of Ru / NiFe-LDH thin-layer two-dimensional nanosheet electrocatalyst.

[0022] SEM images of Ru / NiFe-LDH thin two-dimensional nanosheet electrocatalysts are shown in Figure 1 As shown in the figure, it presents a typical ultra-thin layer morphology with a size of about 150 nm. And low Ru loading does not change its morphology.

[0023] Fine structure EXAFS spectrum such as Figure 2 As shown, the Ru / NiFe-LDH thin-layer two-dimensional nanosheet electrocatalyst exists in the form of single atoms and is coupled to the substrate through Ni-O-Ru covalent interaction. It also reveals that the Ru loading is very low.

[0024] Example 2 This embodiment provides a method for preparing a low-loaded precious metal catalyst for industrial water electrolysis, comprising the following steps: Weigh 0.3 mmol of nickel chloride hexahydrate and 0.9 mmol of chromium chloride hexahydrate respectively and transfer them to a 100 mL glass beaker, add 20 mL of distilled water, and ultrasonically treat for 2 hours to obtain a uniform mixed solution. Then add 0.05 mmol of ruthenium chloride hydrate to the uniform solution, and stir magnetically at 20°C for 1 hour to obtain a uniform mixed solution. Soak the nickel foam in 1.0 M hydrochloric acid solution to remove impurities and oxides on the surface, take out the nickel foam, rinse it with distilled water and anhydrous ethanol three times in sequence, and place it in a vacuum drying oven at 60°C for 10 hours. Add the acid-treated nickel foam to the above uniform solution, heat it to 120°C at a rate of 5°C / min, and hydrothermally react for 16 hours. After cooling to room temperature, take out the catalyst, rinse it with distilled water and anhydrous ethanol three times in sequence, and vacuum dry it at 60°C for 10 hours to obtain 5.05g of Ru / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst.

[0025] The Ru / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst prepared above and 20 wt% Pt / C and RuO2 benchmark catalysts were used for electrocatalytic hydrogen evolution and oxygen evolution. The amount of the benchmark catalyst was 1.0 mg, the test electrolyte was 1.0 MKOH, and the operating temperature was room temperature. Figure 3 The overpotentials of hydrogen evolution and oxygen evolution of Ru / NiCr-LDH at an industrial current density of 1000 mA cm-2 are 190 mV and 380 mV, respectively, which are significantly better than those of 20 wt% Pt / C (419 mV) and RuO2 (768 mV). Figure 4 The assembled Ru / NiCr-LDH ||Ru / NiCr-LDH electrolyzer can achieve an industrial-grade current density of 1000 mA·cm-2 with a cell voltage of only 1.75 V.

[0026] Example 3 This embodiment provides a method for preparing a low-loaded precious metal catalyst for industrial water electrolysis, comprising the following steps: Weigh 0.3 mmol of nickel chloride hexahydrate and 0.6 mmol of chromium chloride hexahydrate respectively and transfer them to a 100 mL glass beaker, add 20 mL of distilled water, and ultrasonically treat for 2 hours to obtain a uniform mixed solution. Then add 0.05 mmol of iridium chloride hydrate to the uniform solution, and stir magnetically at 20°C for 2 hours to obtain a uniform mixed solution. Soak the nickel foam in 1.0 M hydrochloric acid solution to remove impurities and oxides on the surface, take out the nickel foam, rinse it with distilled water and anhydrous ethanol three times in sequence, and place it in a vacuum drying oven at 60°C for 10 hours. Add the acid-treated nickel foam to the above uniform solution, heat it to 180°C at a rate of 5°C / min, and hydrothermally react for 10 hours. After cooling to room temperature, take out the catalyst, rinse it with distilled water and anhydrous ethanol three times in sequence, and vacuum dry it at 60°C for 10 hours to obtain 3.16g of Ir / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst.

[0027] The prepared Ir / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst was assembled into an electrolytic cell and operated stably at an industrial-grade current density of 1000 mA·cm-2 for 300 hours in a 1.0 M KOH electrolyte at room temperature. The durability spectrum is shown in FIG. Figure 3 As shown, there is no performance degradation and the Ir / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst has long-lasting durability.

[0028] Example 4 This embodiment provides a method for preparing a low-loaded precious metal catalyst for industrial water electrolysis, comprising the following steps: Weigh 0.3 mmol nickel chloride hexahydrate and 0.6 mmol cobalt chloride hexahydrate respectively and transfer them to a 100 mL glass beaker, add 20 mL distilled water, and ultrasonically treat for 2 hours to obtain a uniform mixed solution. Then add 0.05 mmol palladium chloride hydrate to the uniform solution, and stir magnetically at 25°C for 2 hours to obtain a uniform mixed solution. Soak the nickel foam in 1.0 M hydrochloric acid solution to remove impurities and oxides on the surface, take out the nickel foam, rinse it with distilled water and anhydrous ethanol three times in sequence, and place it in a vacuum drying oven at 60°C for 10 hours. Add the acid-treated nickel foam to the above uniform solution, heat it to 100°C at a rate of 5°C / min, and hydrothermally react for 16 hours. After cooling to room temperature, take out the catalyst, rinse it with distilled water and anhydrous ethanol three times in sequence, and vacuum dry it at 60°C for 10 hours to obtain 3.23g of Pd / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst.

[0029] The prepared Pd / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst was assembled into an electrolyzer. In a 1.0 M KOH electrolyte, the operating temperature was room temperature and it was stably operated at an industrial-grade current density of 1000 mA·cm-2 for 300 hours without any performance degradation. The Pd / NiCr-LDH thin-layer two-dimensional nanosheet electrocatalyst has long-lasting durability.

[0030] Example 5 This embodiment provides a method for preparing a low-loaded precious metal catalyst for industrial water electrolysis, comprising the following steps: Weigh 0.3 mmol of nickel chloride hexahydrate and 0.6 mmol of manganese chloride hexahydrate respectively and transfer them to a 100 mL glass beaker, add 20 mL of distilled water, and ultrasonically treat for 2 hours to obtain a uniform mixed solution. Then add 0.05 mmol of rhodium chloride hydrate to the uniform solution, and stir magnetically at 30°C for 2 hours to obtain a uniform mixed solution. Soak the nickel foam in 1.0 M hydrochloric acid solution to remove impurities and oxides on the surface, take out the nickel foam, rinse it with distilled water and anhydrous ethanol three times in sequence, and place it in a vacuum drying oven at 60°C for 10 hours. Add the acid-treated nickel foam to the above uniform solution, heat it to 200°C at a rate of 5°C / min, and hydrothermally react for 8 hours. After cooling to room temperature, take out the catalyst, rinse it with distilled water and anhydrous ethanol three times in sequence, and vacuum dry it at 60°C for 10 hours to obtain 3.19g of Rh / NiMn-LDH thin-layer two-dimensional nanosheet electrocatalyst.

[0031] The Rh / NiMn-LDH thin-layer two-dimensional nanosheet electrocatalyst prepared as above was assembled into an electrolyzer. In a 1.0 M KOH electrolyte, the operating temperature was room temperature and it was stably operated at an industrial-grade current density of 1000 mA·cm-2 for 300 hours without any performance degradation. The Rh / NiMn-LDH thin-layer two-dimensional nanosheet electrocatalyst has long-lasting durability.

[0032] Example 6 This embodiment provides a method for preparing a low-loaded precious metal catalyst for industrial water electrolysis, comprising the following steps: Weigh 0.3 mmol of cobalt chloride hexahydrate and 0.6 mmol of ferric chloride hexahydrate respectively and transfer them to a 100 mL glass beaker, add 20 mL of distilled water, and ultrasonically treat for 2 hours to obtain a uniform mixed solution. Then add 0.05 mmol of platinum chloride hydrate to the uniform solution, and stir magnetically at 25°C for 2 hours to obtain a uniform mixed solution. Soak the nickel foam in 1.0 M hydrochloric acid solution to remove impurities and oxides on the surface, take out the nickel foam, rinse it with distilled water and anhydrous ethanol three times in sequence, and place it in a vacuum drying oven at 60°C for 10 hours. Add the acid-treated nickel foam to the above uniform solution, heat it to 100°C at a rate of 5°C / min, and hydrothermally react for 16 hours. After cooling to room temperature, take out the catalyst, rinse it with distilled water and anhydrous ethanol three times in sequence, and vacuum dry it at 60°C for 10 hours to obtain 3.34g of Pt / CoFe-LDH thin-layer two-dimensional nanosheet electrocatalyst.

[0033] The prepared Pt / CoFe-LDH thin-layer two-dimensional nanosheet electrocatalyst was assembled into an electrolyzer. In a 1.0 M KOH electrolyte, the operating temperature was room temperature and it was stably operated at an industrial-grade current density of 1000 mA·cm-2 for 300 hours without any performance degradation. The Pt / CoFe-LDH thin-layer two-dimensional nanosheet electrocatalyst has long-lasting durability.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-loaded noble metal catalyst for industrial water electrolysis, characterized in that: The catalyst uses a thin layer of two-dimensional LDH as a base material and is loaded with an ultra-low loading of precious metals.

2. The low-loaded noble metal catalyst for industrial water electrolysis according to claim 1, characterized in that: The thin-layer two-dimensional LDH includes one or more of NiCr-LDH, NiFe-LDH, NiCo-LDH, CoFe-LDH, and NiMn-LDH.

3. The low-loaded noble metal catalyst for industrial water electrolysis according to claim 1, characterized in that: The precious metal includes one or more of Ru, Rh, Pd, Ag, Ir, Pt, and Au.

4. The low-loaded noble metal catalyst for industrial water electrolysis according to claim 1, characterized in that: The loading amount of the precious metal is 0.1 wt%-0.5 wt% of the substrate material.

5. The method for preparing a low-loaded noble metal catalyst for industrial water electrolysis according to any one of claims 1 to 4, characterized in that: The steps include: (1) mixing the first precursor compound of the LDH substrate material and the second precursor compound in water, and ultrasonically treating at room temperature for 1-6 hours; (2) stirring the mixture after ultrasonic treatment in step (1) with RuCl3 at 20-30°C for 1-3h; (3) mixing the solution stirred in step (2) with the pretreated nickel foam, and then hydrothermally preserving the mixture at 100-200° C. for 8-16 hours; (4) Washing the sample after the hydrothermal treatment in step (3) to remove excess impurities, and drying to obtain a LDH thin layer two-position nanosheet catalyst loaded with precious metals.

6. The method for preparing a low-loaded noble metal catalyst for industrial water electrolysis according to claim 5, characterized in that: The first precursor compound of the LDH substrate material described in step (1) is a nickel-containing compound, and the second precursor compound is one of a chromium-containing compound, an iron-containing compound, a cobalt-containing compound, and a manganese-containing compound.

7. The method for preparing a low-loaded noble metal catalyst for industrial water electrolysis according to claim 6, characterized in that: The nickel-containing compound is one or more of nickel nitrate, nickel carbonate, nickel acetate, and nickel chloride; the chromium-containing compound is one or more of chromium nitrate, chromium carbonate, chromium acetate, and chromium chloride; the iron-containing compound is one or more of iron nitrate, iron carbonate, iron acetate, and iron chloride; the cobalt-containing compound is one or more of cobalt nitrate, cobalt carbonate, cobalt acetate, and cobalt chloride; and the manganese-containing compound is one or more of manganese nitrate, manganese carbonate, manganese acetate, and manganese chloride.

8. The method for preparing a low-loaded noble metal catalyst for industrial water electrolysis according to claim 5, characterized in that: In step (1), the molar ratio of the first compound to the second precursor compound is 1:(1-4).

9. The method for preparing a low-loaded noble metal catalyst for industrial water electrolysis according to claim 5, characterized in that: The size of the LDH thin layer two-dimensional nanosheet catalyst loaded with precious metal obtained in step (4) is 100-800 nm.

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