A Pt-supported NiO nanorod catalyst, its preparation method and application

Abstract

This invention discloses a Pt-supported NiO nanorod catalyst, its preparation method, and its application, belonging to the field of electrocatalytic materials technology. The preparation method includes the following steps: mixing nickel chloride hexahydrate, potassium chloroplatinate, dimethylglyoxime, ultrapure water, and ethanol; heating and stirring the mixture to obtain a mixed solution; centrifuging and drying the solution to obtain a precursor; and calcining the precursor in air to obtain the Pt-supported NiO nanorod catalyst. This invention utilizes the above-mentioned Pt-supported NiO nanorod catalyst, its preparation method, and its application. The preparation method is simple and controllable, and the obtained catalyst exhibits stable structure and excellent activity in seawater electrolysis hydrogen production, effectively meeting the application requirements of seawater electrolysis hydrogen production.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, and in particular to a Pt-supported NiO nanorod catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy carrier, boasts high energy density and zero pollution during its utilization, making it an important clean energy form in the global energy transition. Electrolysis of water is one of the core technological routes for green hydrogen production; however, its large-scale industrial application heavily relies on high-purity freshwater resources, potentially exacerbating global and regional water supply and demand imbalances. Seawater, comprising 96.5% of the world's total water resources, is the most abundant water resource on Earth. Directly using seawater as the electrolyte for hydrogen production can eliminate the dependence on freshwater resources in traditional hydrogen production processes, providing a feasible path for green hydrogen production in water-scarce regions and possessing significant industrial value and application prospects.

[0003] The industrialization of seawater electrolysis for hydrogen production still faces numerous technical bottlenecks. Seawater contains high concentrations of chloride ions, as well as impurities such as calcium and magnesium ions. During electrolysis, chloride ions readily undergo chlorine evolution side reactions on the electrode surface, competing with the main hydrogen evolution reaction for active sites and reducing overall hydrogen production efficiency. Calcium and magnesium ions, on the other hand, easily form insoluble deposits during electrolysis, adhering to the electrode and catalyst surfaces, covering active sites, poisoning the catalyst, severely degrading catalytic performance, and shortening the long-term service life of the electrodes. In the field of hydrogen evolution reaction catalytic materials, platinum-based catalysts exhibit excellent catalytic activity and low reaction overpotential, making them the most outstanding hydrogen evolution catalysts currently available. However, platinum is scarce in the Earth's crust and its raw material costs are high, making it difficult to support large-scale industrial applications. Therefore, non-precious metals are often introduced to prepare alloy catalysts with platinum, reducing the amount of precious metals used while improving catalytic performance through intermetallic synergistic effects. Among these, nickel-based materials are inexpensive, have excellent conductivity and corrosion resistance, and platinum-nickel alloy catalysts can promote water molecule splitting through nickel's oxophilic properties, while platinum mediates hydrogen atom adsorption and hydrogen generation. The synergistic effect of these two processes enhances the kinetics of the hydrogen evolution reaction. However, the existing platinum-nickel alloy catalyst preparation process is generally complicated by cumbersome steps and harsh reaction conditions, making it difficult to simplify the preparation process and control costs while ensuring the effective exposure of catalytic active sites through stable nanostructures. In the complex electrolyte environment of seawater with high salinity and many impurities, the existing nickel oxide-based catalysts with low platinum loading are easily interfered with by chloride ions and impurity ions, resulting in a high overpotential for the hydrogen evolution reaction, and the catalytic activity still cannot meet the actual needs of industrial applications.

[0004] In summary, developing catalytic materials that combine low cost, high hydrogen evolution catalytic activity, and excellent resistance to seawater poisoning is a pressing technical problem that needs to be solved in the field of seawater electrolysis for hydrogen production. Summary of the Invention

[0005] The purpose of this invention is to provide a Pt-supported NiO nanorod catalyst, its preparation method, and its application, in order to solve the above-mentioned problems.

[0006] This invention provides a method for preparing Pt-supported NiO nanorod catalysts, comprising the following preparation steps: S1. Mix nickel metal salt, platinum metal salt, dimethylglyoxime, ultrapure water, and ethanol, heat and stir to react to obtain a precursor solution, and centrifuge and dry to obtain the precursor. S2. The precursor is calcined in air to obtain Pt-supported NiO nanorod catalyst.

[0007] Preferably, in S1, the nickel metal salt includes nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel trichloride.

[0008] Preferably, in S1, the platinum metal salt includes potassium chloroplatinate.

[0009] Preferably, the molar volume ratio of nickel metal salt, platinum metal salt, dimethylglyoxime, ethanol, and water is 0.05–0.2 mol: 0.05–0.2 mol: 0.1–0.5 mol: 10–50 mL: 10–30 mL.

[0010] Preferably, S1 is implemented in the following manner: dissolving nickel metal salt and platinum metal salt in ultrapure water to obtain a platinum-nickel mixed aqueous solution; dissolving dimethylglyoxime in ethanol to obtain a dimethylglyoxime ethanol solution; mixing the platinum-nickel mixed aqueous solution and the dimethylglyoxime ethanol solution and then heating and stirring to react to obtain a precursor solution; wherein the molar ratio of nickel to platinum, calculated by metal element, is 3:1.

[0011] Preferably, in S1, the heating and stirring time is 30-120 min, the temperature is 60-70℃, and the centrifugation is performed twice each with ultrapure water and ethanol, at a speed of 8000 r / min.

[0012] Preferably, in S2, calcination is carried out in an air atmosphere at a temperature of 400–500°C for 2–4 hours.

[0013] A Pt-supported NiO nanorod catalyst is provided, prepared by the above-described method for preparing Pt-supported NiO nanorod catalysts.

[0014] The Pt-supported NiO nanorod catalyst described above is used in the electrolysis of seawater for hydrogen evolution.

[0015] Therefore, the present invention employs the above-mentioned Pt-supported NiO nanorod catalyst, its preparation method, and its application, which has the following beneficial effects: (1) A Pt-supported NiO nanorod catalyst was prepared by calcining a nickel-platinum precursor with dimethylglyoxime. The preparation process is simple, easy to operate and controllable. Compared with the existing multi-step synthesis process, it can effectively reduce the complexity of the process and the preparation cost, and has the feasibility of large-scale production. The air calcination process can completely remove the dimethylglyoxime ligand in the precursor, while effectively maintaining the one-dimensional rod-shaped morphology of the precursor, avoiding the aggregation of active components and the collapse of the nanostructure, and ensuring the full exposure of catalytic active sites. The resulting catalyst is a substrate-free powder structure, which does not rely on self-supporting substrates such as nickel foam or carbon cloth, and can be adapted to various electrode coating and molding processes, making it more flexible in application.

[0016] (2) The catalyst is specifically designed for the hydrogen evolution reaction scenario in seawater, and its catalytic efficiency is achieved through the synergistic effect between Pt and NiO components. The oxygen-loving properties of NiO promote the cracking process of water molecules, while the Pt component mediates the adsorption of hydrogen atoms and the generation of hydrogen gas. Together, they enhance the kinetics of the hydrogen evolution reaction, maintaining excellent catalytic activity even in complex electrolyte systems containing high salt and impurities, such as seawater. Tests using a three-electrode system showed a current density of 10 mA cm⁻¹ in the seawater electrolyte. -2 At this time, the hydrogen evolution overpotential is only 93.2 mV, which can effectively improve the energy efficiency of seawater electrolysis for hydrogen production. It provides a feasible new catalytic material solution for the industrial application of seawater electrolysis for hydrogen production, and is conducive to promoting the efficient development and utilization of seawater resources.

[0017] (3) The obtained Pt-supported NiO one-dimensional nanorods have a stable structure and can maintain structural integrity during electrolysis, exhibiting good long-term operational stability. Furthermore, the complexation-calcination synthesis method employed in this invention has good system universality and can be extended to the preparation of other metal-nickel oxide composite catalytic materials, providing a general and efficient synthesis approach for the development and optimization of similar nickel-based catalytic materials.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 The XRD pattern of the Pt-supported NiO nanorod catalyst prepared in Example 1 of the present invention is shown in the preparation method and application of the present invention. Figure 2 SEM image of the Pt-supported NiO nanorod catalyst prepared in Example 1 of the present invention, its preparation method and application. Figure 3 TEM image of the Pt-supported NiO nanorod catalyst prepared in Example 1 of the present invention, which is a Pt-supported NiO nanorod catalyst, its preparation method and application. Figure 4 The figure shows the test results of the hydrogen evolution performance of the Pt-supported NiO nanorod catalyst prepared in Example 1 and the catalyst prepared in Comparative Example 1 in seawater. This invention provides a Pt-supported NiO nanorod catalyst, its preparation method and application. Detailed Implementation

[0020] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0022] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0023] In the following examples and comparative examples, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods; and unless otherwise specified, the experimental methods used are conventional methods.

[0024] Example 1 A method for preparing a Pt-supported NiO nanorod catalyst includes the following preparation steps: Step 1: Mix 0.05 mol nickel chloride hexahydrate, 0.05 mol potassium chloroplatinate, 0.2 mol dimethyl oxime, 20 mL ultrapure water, and 10 mL ethanol, with a nickel to platinum molar ratio of 3:1. Place the mixed solution in an oil bath and heat and stir at 65°C for 1 hour. After the reaction system cools to room temperature, centrifuge the reaction product, wash it twice with water and twice with ethanol, and then dry it in an oven at 60°C for 6 hours. Step 2: Place the precursor obtained above in a tube furnace, purify with air, calcine at 500℃ for 3 hours, and after calcine is completed, cool the system to 25℃ to obtain the Pt-supported NiO nanorod catalyst.

[0025] Example 2 A method for preparing a Pt-supported NiO nanorod catalyst includes the following preparation steps: Step 1: Mix 0.05 mol nickel chloride hexahydrate, 0.05 mol potassium chloroplatinate, 0.2 mol dimethyl oxime, 20 mL ultrapure water, and 10 mL ethanol, with a nickel to platinum molar ratio of 3:1. Place the mixture in an oil bath and heat and stir at 60°C for 1 hour. After the reaction system cools to room temperature, centrifuge the reaction product, wash it twice with water and twice with ethanol, and then dry it in an oven at 60°C for 6 hours. Step 2: Place the precursor obtained above in a tube furnace, purify with air, calcine at 500℃ for 3 hours, and after calcine is completed, cool the system to 25℃ to obtain the Pt-supported NiO nanorod catalyst.

[0026] Example 3 A method for preparing a Pt-supported NiO nanorod catalyst includes the following preparation steps: Step 1: Mix 0.05 mol nickel chloride hexahydrate, 0.05 mol potassium chloroplatinate, 0.2 mol dimethyl oxime, 20 mL ultrapure water, and 10 mL ethanol, with a nickel to platinum molar ratio of 3:1. Place the mixture in an oil bath and heat and stir at 65°C for 1 hour. After the reaction system cools to room temperature, centrifuge the reaction product, wash it twice with water and twice with ethanol, and then dry it in an oven at 60°C for 6 hours. Step 2: Place the precursor obtained above in a tube furnace, purify with air, calcine at 400℃ for 2 hours, and after calcine is completed, cool the system to 25℃ to obtain the Pt-supported NiO nanorod catalyst.

[0027] Comparative Example 1 A method for preparing a NiO nanorod catalyst includes the following preparation steps: Step 1: Mix 0.05 mol nickel chloride hexahydrate, 0.2 mol dimethylglyoxime, 15 mL ultrapure water and 10 mL ethanol. Let the mixture stand at room temperature to obtain nickel dimethylglyoxime. After centrifuging the reaction product, wash it twice with water and twice with ethanol, and then dry it in an oven at 60°C for 6 hours. Step 2: Place the obtained nickel dimethylglyoxime in a tube furnace, purify with air, calcine at 400°C for 2 hours, and after calcine is completed, cool the system to 25°C to obtain NiO nanorod catalyst that is in full contact with air.

[0028] Characterization and detection: The composition of the Pt-supported NiO nanorod catalyst prepared in Example 1 was analyzed using X-ray diffraction. The XRD results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the characteristic peaks of the Pt-supported NiO nanorod catalyst prepared in Example 1 correspond to those of the standard card, confirming that the present invention has successfully prepared a Pt-supported NiO nanorod catalyst.

[0029] The Pt-supported NiO nanorod catalyst prepared in Example 1 was characterized using scanning electron microscopy (SEM), such as... Figure 2 As shown, the Pt-supported NiO nanorod catalyst exhibits a one-dimensional rod-like structure.

[0030] The Pt-supported NiO nanorod catalyst prepared in Example 1 was observed using field emission transmission electron microscopy (TEM). Figure 3 As shown, the Pt-supported NiO nanorod catalyst prepared in this invention still maintains a one-dimensional rod-shaped structure.

[0031] A three-electrode system was used, with the Pt-supported NiO nanorod catalyst prepared in Example 1 as the cathode. The catalytic performance of the product from Example 1 was tested in a seawater system. Figure 4 As shown, from Figure 4 It can be seen that the Pt-supported NiO nanorod catalyst at 10 mA cm⁻¹ -2 Only 93.2 mV overpotential is required at that time.

[0032] like Figure 4 As shown in the comparative experiments of Example 1 and Comparative Example 1, the pure nickel oxide nanorod catalyst is limited by its insufficient hydrogen adsorption and desorption capacity, resulting in a high energy barrier for the hydrogen evolution reaction and significant limitations in hydrogen evolution performance in seawater systems. The platinum-supported nickel oxide nanorod catalyst prepared in Example 1 can exert its catalytic effect through the synergistic effect of platinum and nickel oxide components. It leverages the oxygen-loving properties of nickel oxide to promote water molecule splitting, and utilizes platinum active sites to mediate hydrogen atom adsorption and hydrogen generation, accelerating the hydrogen evolution reaction kinetics. In seawater electrolyte at 10 mA cm⁻¹, it achieves this effect. -2 The hydrogen evolution overpotential can reach 93.2 mV at current density, and its catalytic activity is significantly better than that of pure nickel oxide nanorod catalysts.

[0033] The nickel-platinum bimetallic complex precursor exhibits superior thermal resistance, maintaining its intact one-dimensional nanorod morphology even under air calcination at 500℃, thus preventing grain agglomeration and structural collapse at high temperatures. Simultaneously, the relatively higher calcination temperature more thoroughly removes dimethylglyoxime ligands and residual impurities from the precursor, improving the crystallinity of the nickel oxide phase and enhancing the long-term operational stability of the catalyst in the complex corrosive environment of seawater. For the nickel-platinum bimetallic reaction system, the heating and stirring reaction conditions promote the uniform complexation of the two metal ions with dimethylglyoxime, preventing component segregation and ensuring uniform dispersion of the platinum component on the surface of the nickel oxide nanorods after calcination, providing a structural basis for stable catalytic activity.

[0034] Therefore, this invention employs the aforementioned method for preparing and applying a Pt-supported NiO nanorod catalyst. The catalyst is prepared by calcining a nickel-platinum precursor with dimethylglyoxime followed by air calcination. This process is simple, easy to operate, and controllable. Compared to existing multi-step synthesis processes, it effectively reduces process complexity and preparation costs, making large-scale production feasible. The air calcination process effectively removes the dimethylglyoxime ligand from the precursor while maintaining its one-dimensional rod-like morphology, preventing aggregation of active components and nanostructure collapse, and ensuring full exposure of catalytic active sites. The resulting catalyst is a substrate-free powder structure, eliminating the need for self-supporting substrates such as nickel foam or carbon cloth, making it adaptable to various electrode coating and molding processes, thus offering greater application flexibility.

[0035] The catalyst is specifically designed for the hydrogen evolution reaction in seawater, leveraging the synergistic effect between Pt and NiO components to enhance catalytic efficiency. NiO's oxygen-loving properties promote the splitting of water molecules, while the Pt component mediates hydrogen atom adsorption and hydrogen generation. Together, they enhance the kinetics of the hydrogen evolution reaction, maintaining excellent catalytic activity even in complex electrolyte systems containing high salt and impurities, such as seawater. Testing with a three-electrode system showed a current density of 10 mA cm⁻¹ in the seawater electrolyte. -2 At this time, the hydrogen evolution overpotential is only 93.2 mV, which can effectively improve the energy efficiency of seawater electrolysis for hydrogen production. It provides a feasible new catalytic material solution for the industrial application of seawater electrolysis for hydrogen production, and is conducive to promoting the efficient development and utilization of seawater resources.

[0036] The resulting Pt-supported NiO one-dimensional nanorods exhibit stable structures, maintaining structural integrity during electrolysis and demonstrating excellent long-term operational stability. Furthermore, the complexation-calcination synthesis method employed in this invention possesses good system universality and can be extended to the preparation of other metal-nickel oxide composite catalytic materials, providing a general and efficient synthetic approach for the development and optimization of similar nickel-based catalytic materials.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a Pt-supported NiO nanorod catalyst, characterized in that, The preparation steps include the following: S1. Mix nickel metal salt, platinum metal salt, dimethylglyoxime, ultrapure water, and ethanol, heat and stir to react to obtain a precursor solution, and centrifuge and dry to obtain the precursor. S2. The precursor is calcined in air to obtain Pt-supported NiO nanorod catalyst.

2. The method for preparing a Pt-supported NiO nanorod catalyst according to claim 1, characterized in that, In S1, nickel metal salts include nickel chloride hexahydrate, nickel nitrate hexahydrate, and nickel trichloride.

3. The method for preparing a Pt-supported NiO nanorod catalyst according to claim 1, characterized in that, In S1, platinum metal salts include potassium chloroplatinate.

4. The method for preparing a Pt-supported NiO nanorod catalyst according to claim 1, characterized in that, The molar volume ratio of nickel metal salt, platinum metal salt, dimethylglyoxime, ethanol, and water is 0.05–0.2 mol: 0.05–0.2 mol: 0.1–0.5 mol: 10–50 mL: 10–30 mL.

5. The method for preparing a Pt-supported NiO nanorod catalyst according to claim 1, characterized in that, S1 is implemented in the following manner: nickel metal salt and platinum metal salt are dissolved in ultrapure water to obtain a platinum-nickel mixed aqueous solution; dimethylglyoxime is dissolved in ethanol to obtain a dimethylglyoxime ethanol solution; the platinum-nickel mixed aqueous solution and the dimethylglyoxime ethanol solution are mixed and heated and stirred to obtain a precursor solution; wherein the molar ratio of nickel to platinum is 3:1 based on metal elements.

6. The method for preparing a Pt-supported NiO nanorod catalyst according to claim 1, characterized in that, In S1, the heating and stirring time is 30-120 min, the temperature is 60-70℃, and the centrifugation is performed twice each with ultrapure water and ethanol, at a speed of 8000 r / min.

7. The method for preparing a Pt-supported NiO nanorod catalyst according to claim 1, characterized in that, In S2, calcination is carried out in an air atmosphere at a temperature of 400–500°C for 2–4 hours.

8. A Pt-supported NiO nanorod catalyst prepared by the method for preparing Pt-supported NiO nanorod catalyst according to any one of claims 1-7.

9. The application of the Pt-supported NiO nanorod catalyst as described in claim 8 in the electrolysis of seawater for hydrogen evolution.

Images