A Pt-Ni(OH)2 composite hydrogen evolution catalyst, its preparation method and application
A Pt-Ni(OH)2 composite catalyst was prepared by a one-step solvothermal method. Pt was inserted into the interlayer of α-Ni(OH)2 to expand the interlayer spacing, which solved the problems of cumbersome and unsatisfactory activity of traditional methods. This method achieved a simple and efficient catalyst preparation and excellent alkaline water electrolysis hydrogen production performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- FOSHAN XIANHU LAB
- Filing Date
- 2024-12-03
- Publication Date
- 2026-06-30
AI Technical Summary
The existing Pt-Ni(OH)2 composite catalyst has a complicated preparation process and unsatisfactory catalytic activity, making it difficult to meet the needs of large-scale preparation and alkaline water electrolysis for hydrogen production.
A Pt-Ni(OH)2 composite hydrogen evolution catalyst was prepared by a one-step solvothermal method. The catalyst was prepared by dissolving a platinum source, a nickel salt, and urea and then carrying out a hydrothermal reaction. After cooling, the solid and liquid were separated, washed, and freeze-dried. Pt was inserted into the interlayer of α-Ni(OH)2 to expand the interlayer spacing, expose more active sites, and improve the mass transfer process.
The preparation process is simplified and the catalytic activity is improved, especially in alkaline electrolytes, where the hydrogen evolution reaction rate and catalytic performance are significantly enhanced, making it suitable for large-scale production.
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Figure CN119800422B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a Pt-Ni(OH)2 composite hydrogen evolution catalyst, its preparation method, and its application. Background Technology
[0002] Hydrogen production by electrolyzing water using renewable energy is a safe, environmentally friendly, and efficient method. Theoretically, it can achieve a thermodynamic conversion efficiency of 80%, and the resulting hydrogen is known as "green hydrogen," which has broad development prospects.
[0003] The hydrogen evolution reaction (HER) at the cathode of water electrolysis involves three possible steps: the first step is the Volmer reaction, followed by either the Heyrovsky reaction or the Tafel reaction. Platinum (Pt) is considered the optimal element for catalyzing the HER; however, under alkaline conditions, due to slow water dissociation and poor proton supply rates, the kinetics of the HER on Pt are significantly slower, resulting in a reaction rate that is often 2-3 orders of magnitude lower than that of acidic electrolytes. Nickel (Ni) hydroxide, due to its strong water dissociation ability, is often used to improve the catalytic activity of Pt in alkaline water electrolysis. Traditional Pt-Ni(OH)₂ composite catalysts are typically prepared using a two-step method: first, Ni(OH)₂ is prepared, followed by the reduction of Pt to the Ni(OH)₂ surface. This preparation process is relatively cumbersome, hindering large-scale catalyst production, and the catalytic activity of the prepared Pt-Ni(OH)₂ composite catalyst is not ideal.
[0004] Therefore, there is an urgent need to develop a simple and rapid method for preparing Pt-Ni(OH)2 composite catalysts, and to make the prepared catalysts have high catalytic activity for alkaline water electrolysis to produce hydrogen. Summary of the Invention
[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a Pt-Ni(OH)₂ composite hydrogen evolution catalyst, its preparation method, and its application. The preparation method employs a one-step solvothermal process, which can simply, rapidly, and on a large scale prepare the Pt-Ni(OH)₂ composite hydrogen evolution catalyst. Furthermore, in the composite hydrogen evolution catalyst, Pt is inserted into the interlayer of α-Ni(OH)₂, expanding the interlayer spacing of α-Ni(OH)₂ and exposing more active sites, thereby accelerating the mass transfer process and improving the catalytic performance of alkaline water electrolysis for hydrogen evolution.
[0006] To address the aforementioned technical problems, the first aspect of this invention provides a method for preparing a Pt-Ni(OH)2 composite hydrogen evolution catalyst, comprising the following steps:
[0007] (1) Dissolve the platinum source, nickel salt, and urea in a solvent and disperse them to obtain a mixed solution;
[0008] (2) The mixed solution is transferred to a reaction vessel for hydrothermal reaction. After cooling, the reaction product is separated into solid and liquid components to obtain a solid product.
[0009] (3) The solid product is washed and freeze-dried to obtain the Pt-Ni(OH)2 composite hydrogen evolution catalyst.
[0010] Specifically, this invention employs a one-step solvothermal method to prepare a Pt-Ni(OH)₂ composite hydrogen evolution catalyst. Compared to the traditional two-step method, this method is not only simpler and suitable for large-scale production, but also allows the Ni(OH)₂ component in the prepared composite catalyst to rapidly dissociate water molecules in the alkaline electrolyte into protons, which are then rapidly transferred to Pt sites. At these Pt sites, a rapid Tafel reaction occurs, significantly improving the hydrogen evolution catalytic activity in the alkaline electrolyte. Simultaneously, in the composite hydrogen evolution catalyst prepared by the one-step solvothermal method, Pt is inserted into the interlayer of α-Ni(OH)₂, resulting in an expanded interlayer spacing, exposing more active sites. This accelerates the mass transfer process, improves electron transfer pathways, increases proton conductivity, and promotes rapid transfer of reactants and products, thereby effectively enhancing catalytic activity.
[0011] In some embodiments of the present invention, the platinum source is selected from at least one of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, potassium tetrachloroplatinate, and sodium tetrachloroplatinate.
[0012] In some embodiments of the present invention, the nickel salt is selected from at least one of nickel chloride, nickel nitrate, and nickel sulfate. For example, nickel nitrate and its hydrate, nickel chloride and its hydrate, and nickel sulfate and its hydrate.
[0013] In some embodiments of the present invention, the mass ratio of the platinum source to the nickel salt is 10:(1-100). Preferably, the mass ratio of the platinum source to the nickel salt is 10:(10-50). More preferably, the mass ratio of the platinum source to the nickel salt is 10:(20-40).
[0014] In some embodiments of the present invention, the mass ratio of the nickel salt to urea is 1:(0.1-10). Preferably, the mass ratio of the nickel salt to urea is 1:(0.5-5). More preferably, the mass ratio of the nickel salt to urea is 1:(0.8-4).
[0015] In some embodiments of the present invention, the solvent includes ethylene glycol and water.
[0016] In some embodiments of the present invention, the volume ratio of ethylene glycol to water is 10:(1-10). Preferably, the volume ratio of ethylene glycol to water is 10:(1-5). More preferably, the volume ratio of ethylene glycol to water is 10:(1-3).
[0017] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 120-180°C. Preferably, the temperature of the hydrothermal reaction is 140-160°C.
[0018] In some embodiments of the present invention, the hydrothermal reaction takes 0.5-6 hours. Preferably, the hydrothermal reaction takes 2-6 hours.
[0019] A second aspect of the present invention provides a Pt-Ni(OH)2 composite hydrogen evolution catalyst, which is prepared by the above-described preparation method. The Pt-Ni(OH)2 composite hydrogen evolution catalyst comprises Pt and α-Ni(OH)2, wherein the Pt is inserted into the interlayer of α-Ni(OH)2 and expands the interlayer spacing of α-Ni(OH)2.
[0020] Specifically, the Pt-Ni(OH)2 composite hydrogen evolution catalyst prepared by this invention comprises Pt and α-Ni(OH)2. α-Ni(OH)2 consists of Ni(OH)2 layers intercalated with anions or water molecules, exhibiting stronger mass transfer capabilities and thus higher catalytic activity compared to β-Ni(OH)2 formed by hexagonal close-packing. Simultaneously, the insertion of Pt into the interlayer space of α-Ni(OH)2 further expands the interlayer spacing. This expanded interlayer spacing exposes more active sites and facilitates faster mass transfer, improved electron transfer pathways, increased proton conductivity, and rapid transfer of reactants and products, thereby effectively enhancing catalytic activity.
[0021] A third aspect of this invention provides the application of the above-mentioned Pt-Ni(OH)₂ composite hydrogen evolution catalyst in alkaline water electrolysis for hydrogen production. The Pt-Ni(OH)₂ composite hydrogen evolution catalyst prepared by this invention exhibits good electrocatalytic hydrogen evolution activity under alkaline conditions.
[0022] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages:
[0023] (1) The present invention employs a one-step solvothermal method to prepare a Pt-Ni(OH)2 composite hydrogen evolution catalyst, wherein the Ni(OH)2 component can rapidly dissociate water molecules in the alkaline electrolyte into protons, which are then rapidly transferred to Pt sites, where a rapid Tafel reaction occurs, significantly improving the hydrogen evolution catalytic activity in the alkaline electrolyte. Simultaneously, in the composite catalyst prepared by the one-step solvothermal method, the interlayer spacing of α-Ni(OH)2 is further expanded, exposing more active sites, accelerating the mass transfer process, improving the electron transfer pathway, increasing proton conductivity, and promoting the rapid transfer of reactants and products, thereby effectively enhancing the catalytic activity.
[0024] (2) The one-step solvothermal method used in this invention to prepare Pt-Ni(OH)2 composite hydrogen evolution catalyst is simple, fast and efficient, the reaction conditions are controllable, the utilization rate of the precious metal Pt is high, the catalyst prepared has good uniformity, and it is suitable for mass production.
[0025] (3) The Pt-Ni(OH)2 composite hydrogen evolution catalyst prepared in this invention has good electrocatalytic hydrogen evolution performance, and when the current density reaches -10 mA / cm², it exhibits excellent performance. -2 At that time, the overpotential was 39-46mV, which is superior to that of commercial platinum-carbon catalysts. Attached Figure Description
[0026] Figure 1 This is a flowchart illustrating the preparation of the Pt-Ni(OH)2 composite hydrogen evolution catalyst according to the present invention;
[0027] Figure 2 The X-ray diffraction patterns of the Pt-Ni(OH)2 composite hydrogen evolution catalysts prepared in Examples 1-2 of this invention are shown below.
[0028] Figure 3 X-ray diffraction patterns of the hydrogen evolution catalysts prepared in Comparative Examples 2-3 of this invention;
[0029] Figure 4 Comparison of electrochemical polarization curves of the Pt-Ni(OH)2 composite hydrogen evolution catalysts prepared in Examples 1-3 of this invention in 1M potassium hydroxide solution. Detailed Implementation
[0030] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.
[0031] like Figure 1 As shown, the preparation method of the Pt-Ni(OH)2 composite hydrogen evolution catalyst provided by the present invention includes the following steps:
[0032] (1) Dissolve the platinum source, nickel salt, and urea in a mixed solution of ethylene glycol and water, and stir to disperse them evenly to obtain a mixed solution;
[0033] (2) Transfer the mixed solution obtained in step (1) to the reaction vessel and carry out a hydrothermal reaction to obtain the reaction product;
[0034] (3) The reaction product obtained in step (2) is centrifuged, washed and freeze-dried to obtain the Pt-Ni(OH)2 composite hydrogen evolution catalyst.
[0035] Example 1
[0036] A method for preparing a Pt-Ni(OH)2 composite hydrogen evolution catalyst includes the following steps:
[0037] (1) Weigh out 0.6 g of nickel nitrate hexahydrate, 0.5 g of urea and 0.2 g of potassium chloroplatinate respectively, and dissolve them in a mixture of 4 ml of water and 28 ml of ethylene glycol solution. Stir and sonicate thoroughly to dissolve completely to obtain a mixed solution.
[0038] (2) Transfer the mixed solution obtained in step (1) to the reaction vessel and carry out hydrothermal reaction at 140°C for 2 hours. After naturally cooling to room temperature, centrifuge the reaction product to separate the solid and liquid components and obtain the solid product.
[0039] (3) The solid product obtained in step (2) is washed three times with ultrapure water and ethanol respectively, and then freeze-dried to obtain the Pt-Ni(OH)2 composite hydrogen evolution catalyst of this embodiment.
[0040] Example 2
[0041] A method for preparing a Pt-Ni(OH)2 composite hydrogen evolution catalyst includes the following steps:
[0042] (1) Weigh out 0.6 g of nickel nitrate hexahydrate, 2.0 g of urea and 0.2 g of chloroplatinic acid hexahydrate respectively, and dissolve them in a mixture of 4 ml of water and 28 ml of ethylene glycol solution. Stir and sonicate thoroughly to dissolve completely to obtain a mixed solution.
[0043] (2) Transfer the mixed solution obtained in step (1) to the reaction vessel and carry out hydrothermal reaction at 140°C for 2 hours. After naturally cooling to room temperature, centrifuge the reaction product to separate the solid and liquid components and obtain the solid product.
[0044] (3) The solid product obtained in step (2) is washed three times with ultrapure water and ethanol respectively, and then freeze-dried to obtain the Pt-Ni(OH)2 composite hydrogen evolution catalyst of this embodiment.
[0045] Example 3
[0046] A method for preparing a Pt-Ni(OH)2 composite hydrogen evolution catalyst includes the following steps:
[0047] (1) Weigh out 0.6 g of nickel nitrate hexahydrate, 0.5 g of urea and 0.2 g of potassium chloroplatinate respectively, and dissolve them in a mixture of 4 ml of water and 28 ml of ethylene glycol solution. Stir and sonicate thoroughly to dissolve completely to obtain a mixed solution.
[0048] (2) Transfer the mixed solution obtained in step (1) to the reaction vessel and carry out hydrothermal reaction at 160°C for 6 hours. After naturally cooling to room temperature, centrifuge the reaction product to separate the solid and liquid components and obtain the solid product.
[0049] (3) The solid product obtained in step (2) is washed three times with ultrapure water and ethanol respectively, and then freeze-dried to obtain the Pt-Ni(OH)2 composite hydrogen evolution catalyst of this embodiment.
[0050] Comparative Example 1
[0051] A commercially available Pt / C catalyst (TANAKATK, model: TEC10E20E, with a platinum loading of 20 wt.%) was used as the hydrogen evolution catalyst in Comparative Example 1.
[0052] Comparative Example 2
[0053] The difference between Comparative Example 2 and Example 1 is that the hydrogen evolution catalyst prepared in Comparative Example 2 does not contain Pt and is a single α-Ni(OH)2. Its preparation method includes the following steps:
[0054] (1) Weigh 0.6 g of nickel nitrate hexahydrate and 0.5 g of urea respectively, and dissolve them in a mixture of 4 ml of water and 28 ml of ethylene glycol solution. Stir and sonicate thoroughly to dissolve them completely to obtain a mixed solution.
[0055] (2) Transfer the mixed solution obtained in step (1) to the reaction vessel and carry out hydrothermal reaction at 140°C for 2 hours. After naturally cooling to room temperature, centrifuge the reaction product to separate the solid and liquid components and obtain the solid product.
[0056] (3) The solid product obtained in step (2) was washed three times with ultrapure water and ethanol respectively, and then freeze-dried to obtain the α-Ni(OH)2 hydrogen evolution catalyst of this comparative example.
[0057] Comparative Example 3
[0058] The difference between Comparative Example 3 and Example 1 is that a two-step solvothermal method was used to prepare the Pt-Ni(OH)2 composite hydrogen evolution catalyst, and the preparation method includes the following steps:
[0059] (1) Weigh 0.6 g of nickel nitrate hexahydrate and 0.5 g of urea respectively, and dissolve them in a mixture of 4 mL of water and 28 mL of ethylene glycol solution. Stir and sonicate thoroughly to completely dissolve them to obtain a mixed solution. Then transfer the mixed solution to a reaction vessel and carry out a hydrothermal reaction at 140 °C for 2 hours. After naturally cooling to room temperature, separate the reaction product into solid and liquid products to obtain a solid product. Wash the obtained solid product three times with ultrapure water and ethanol respectively, and finally freeze dry to obtain α-Ni(OH)2 hydrogen evolution catalyst.
[0060] (2) Disperse the α-Ni(OH)2 hydrogen evolution catalyst obtained in step (1) and 0.2 g of potassium chloroplatinate in 20 mL of ethylene glycol solution, stir thoroughly and sonicate to completely dissolve the potassium chloroplatinate and ensure that α-Ni(OH)2 is evenly dispersed; then transfer the dispersed solution to a reaction vessel and react at 140 °C for 2 hours. After it cools naturally to room temperature, the reaction product is obtained; then the reaction product is centrifuged to separate the solid and liquid phases to obtain the solid product.
[0061] (3) The solid product obtained in step (2) was washed three times with ultrapure water and ethanol respectively; then it was freeze-dried to obtain the Pt-Ni(OH)2 composite hydrogen evolution catalyst of this comparative example.
[0062] Performance testing
[0063] 1. Component analysis
[0064] Figure 2 The X-ray diffraction patterns are those of the Pt-Ni(OH)2 composite hydrogen evolution catalysts prepared in Examples 1-2 of this invention. Figure 2The horizontal axis 2-Theta represents the 2θ angle, and the vertical axis Intensity represents the intensity of the diffraction peaks. Among them, the diffraction peaks at 39.6°, 46.5° and 67.5° correspond to the (111), (200) and (220) crystal planes of Pt, respectively; the diffraction peaks at 33.4° and 59.9° correspond to the (101) and (110) crystal planes of α-Ni(OH)2, respectively; and the diffraction peak near 10° corresponds to the (003) crystal plane of α-Ni(OH)2.
[0065] Figure 3 The X-ray diffraction patterns of the hydrogen evolution catalysts prepared in Comparative Examples 2-3 of this invention are shown. The α-Ni(OH)₂ hydrogen evolution catalyst prepared in Comparative Example 2 is consistent with the standard card (JCPDS 38-0715), where the diffraction peaks at 11.3°, 22.7°, 33.4°, and 59.9° correspond to the (003), (006), (101), and (110) crystal planes of α-Ni(OH)₂, respectively. The Pt-Ni(OH)₂ hydrogen evolution catalyst sample prepared in Comparative Example 3 exhibits similar α-Ni(OH)₂ diffraction peaks, with the diffraction peaks at 39.6°, 46.5°, and 67.5° corresponding to the (111), (200), and (220) crystal planes of Pt, respectively.
[0066] α-Ni(OH)₂ consists of Ni(OH)₂ layers intercalated with anions or water molecules, exhibiting stronger mass transfer capabilities compared to β-Ni(OH)₂ formed by hexagonal close-packing. Therefore, α-Ni(OH)₂ possesses higher catalytic activity than β-Ni(OH)₂. Figure 2 and Figure 3 A comparison reveals that in the Pt-Ni(OH)₂ composite hydrogen evolution catalysts prepared in Examples 1-2 of this invention, the (003) crystal plane of α-Ni(OH)₂ shows a significant shift to a lower angle (from 11.3° to 10°) compared to Comparative Examples 2 and 3. This indicates that the interlayer spacing of α-Ni(OH)₂ in the composite catalyst prepared by the one-step solvothermal method is further expanded. This is likely due to the insertion of Pt into the interlayer of the octahedral α-Ni(OH)₆. This further expanded interlayer spacing exposes more active sites and accelerates the mass transfer process, improves electron transfer pathways, increases proton conductivity, and promotes rapid transfer of reactants and products, thereby effectively enhancing catalytic activity.
[0067] 2. Electrocatalytic hydrogen evolution performance
[0068] A 1 mol / L potassium hydroxide solution was prepared as the electrolyte for electrocatalysis. The Pt-Ni(OH)₂ composite hydrogen evolution catalyst, Hg / HgO electrode, and carbon rod electrode prepared in Examples 1-3 were connected to an electrochemical workstation as the working electrode, reference electrode, and counter electrode, respectively. Linear voltammetry tests were performed on the electrode materials at a scan rate of 10 mV / s. The measured electrochemical polarization curves are shown below. Figure 4 As shown, Figure 4 The horizontal axis represents voltage, and the vertical axis represents current density. From... Figure 4 As can be seen from this, when the current density reaches 10 mA / cm², -2 At that time, the overpotential of the Pt-Ni(OH)2 composite hydrogen evolution catalysts prepared in Examples 1-3 was 39-46 mV. The electrocatalytic hydrogen evolution performance of the hydrogen evolution catalysts prepared in Comparative Examples 1-3 was measured using the same testing method, and the results are shown in Table 1.
[0069] Table 1:
[0070] sample <![CDATA[10mAcm -2 Overpotential (mV) at time Example 1 39 Example 2 46 Example 3 42 Comparative Example 1 56 Comparative Example 2 120 Comparative Example 3 63
[0071] As shown in Table 1, the Pt-Ni(OH)2 composite hydrogen evolution catalysts prepared in Examples 1-3 of this invention all exhibit good electrocatalytic hydrogen evolution performance, with a 10 mA cm⁻¹ value. -2 The overpotential is as low as 39-46 mV, which is superior to the electrocatalytic hydrogen evolution performance of the commercially available Pt / C catalyst in Comparative Example 1.
[0072] The hydrogen evolution catalyst of Comparative Example 2, compared to Example 1, does not contain Pt, and its 10 mA cm⁻¹... -2 The overpotential at that time was 120mV, which is much higher than the 39mV in Example 1, indicating that Pt has a good promoting effect on the electrocatalytic hydrogen evolution performance of α-Ni(OH)2.
[0073] Compared to Example 1, the hydrogen evolution catalyst of Comparative Example 3, due to the use of the conventional two-step solvothermal method, has Pt supported on the surface of Ni(OH)2 in the prepared Pt-Ni(OH)2 composite hydrogen evolution catalyst. The interlayer spacing of Ni(OH)2 is not expanded, and there are fewer exposed active sites compared to Example 1. Therefore, its catalytic activity is not as good as that of Example 1.
[0074] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.
Claims
1. A method for preparing a Pt-Ni(OH)2 composite hydrogen evolution catalyst, characterized by, Includes the following steps: (1) Dissolve the platinum source, nickel salt, and urea in a solvent and disperse them to obtain a mixed solution; The mass ratio of the platinum source to the nickel salt is 10:(1-100), the mass ratio of the nickel salt to urea is 1:(0.1-10), and the solvent includes ethylene glycol and water, with a volume ratio of ethylene glycol to water of 10:(1-10). (2) The mixed solution is transferred to a reaction vessel for hydrothermal reaction. After cooling, the reaction product is separated into solid and liquid components to obtain a solid product. The hydrothermal reaction temperature is 120-180℃, and the hydrothermal reaction time is 0.5-6 hours; (3) The solid product is washed and freeze-dried to obtain the Pt-Ni(OH)2 composite hydrogen evolution catalyst.
2. The preparation method of the Pt-Ni(OH)2 composite hydrogen evolution catalyst according to claim 1, characterized in that, The platinum source is selected from at least one of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, potassium tetrachloroplatinate, and sodium tetrachloroplatinate.
3. The preparation method of the Pt-Ni(OH)₂ composite hydrogen evolution catalyst according to claim 1, characterized in that, The nickel salt is selected from at least one of nickel chloride, nickel nitrate, and nickel sulfate.
4. A Pt-Ni(OH)₂ composite hydrogen evolution catalyst, characterized in that, The Pt-Ni(OH)2 composite hydrogen evolution catalyst, prepared by any one of claims 1-3, comprises Pt and α-Ni(OH)2, wherein the Pt is inserted into the interlayer of α-Ni(OH)2 and expands the interlayer spacing of α-Ni(OH)2.
5. The application of the Pt-Ni(OH)2 composite hydrogen evolution catalyst according to claim 4 in alkaline water electrolysis for hydrogen production.