Preparation method of alkaline high-current-density decomposition water electric catalyst
By preparing a heterogeneous interface catalyst coupled with nickel and cerium oxide, the problem of scarcity of precious metals and low activity of non-precious metals in alkaline water electrolysis for hydrogen production was solved, achieving efficient and stable hydrogen evolution through water electrolysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU JIANGKE GRAPHENE RES INST CO LTD
- Filing Date
- 2023-07-03
- Publication Date
- 2026-04-24
AI Technical Summary
In existing alkaline water electrolysis hydrogen production technologies, precious metal catalysts are scarce and expensive, while non-precious metal catalysts have low activity under alkaline conditions, making them difficult to apply effectively at high current densities. Furthermore, cerium oxide has poor activity when used alone, failing to meet the requirements for efficient water splitting.
A heterogeneous interface catalyst coupled with nickel and cerium oxide was prepared by hydrothermal and calcination methods. By regulating the electronic structure and increasing the active sites, a hydrophilic and gas-phobic surface was formed, thereby improving the electrocatalytic performance.
It exhibits excellent electrocatalytic activity and stability at high current densities, even surpassing commercial Pt/C catalysts, and possesses efficient and stable hydrogen evolution performance in water electrolysis.
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Abstract
Description
Technical Field
[0003] This invention belongs to the field of electrocatalysis technology in composite catalyst materials, specifically relating to a nickel-cerium oxide coupled heterostructure catalyst and its preparation method. Background Technology
[0004] Overexploitation and consumption of fossil fuels have led to an energy crisis and environmental pollution, making the development of environmentally friendly renewable energy a major trend. Currently, the most common hydrogen production methods are water gasification and hydrocarbon cracking, but fossil fuel reforming for hydrogen production cannot escape dependence on traditional energy sources and also causes environmental pollution. Alkaline water electrolysis has attracted widespread attention due to its ability to effectively avoid acid corrosion; however, the low hydrogen ion concentration in alkaline electrolytes results in slow kinetics for water splitting to produce hydrogen under alkaline conditions, with its activity being 2-3 orders of magnitude lower than that of acidic electrolytes. Therefore, it is necessary to develop efficient and stable catalysts for the hydrogen evolution reaction (HER) in water electrolysis, especially under high current density conditions (at least 100 mA cm⁻¹). -2 Currently, platinum group metals exhibit excellent water-splitting performance, but their scarcity and high price greatly limit their large-scale use in modern industrial applications. To address this issue, researchers have begun to explore non-precious metal catalysts with high catalytic activity and abundant, economical availability for industrial-scale water electrolysis to produce hydrogen.
[0005] Ni, an element in the same group as Pt, is abundant and inexpensive, and is not easily corroded or dissolved under alkaline conditions. However, metallic Ni does not exhibit high actual activity for electrocatalytic reactions (HER). In recent years, researchers have begun to improve the electrocatalytic performance of nickel-based catalysts through methods such as alloying with other metals, forming compounds with nonmetals, heteroatom doping, and constructing composite materials. Cerium oxide is widely used in electrocatalytic materials among rare earth metal oxides, and its oxidation state Ce... 4+ and Ce 3+ The ability to flexibly switch between them leads to CeO x Its unique electronic structure and abundant oxygen vacancies facilitate water adsorption and dissociation, thus exhibiting excellent corrosion resistance and stability even at high current densities. However, due to CeO... x CeO has very poor reactivity in the hydrogen evolution reaction, therefore it is used alone. x This approach may not meet the requirements for efficient water splitting. Previous research has often employed synergistic coupling of cerium oxide with other transition metals and their compounds to modulate the catalyst's electronic structure, thereby improving the catalyst's hydrogen evolution performance in alkaline environments. Therefore, there is an urgent need to develop a highly efficient and cost-effective alkaline water electrolysis catalyst for hydrogen production. Summary of the Invention
[0006] To address the problems existing in current alkaline water electrolysis technology, this study designed a heterogeneous interface catalyst composed of rare earth metal oxides and transition metals, and synthesized Ni / CeO in two steps using a hydrothermal method and a calcination method. x @C, with its abundant active sites and unique hydrophilic and gas-repellent structure, makes it a highly active and stable alkaline high-current HER electrocatalyst.
[0007] This invention is achieved through the following technical solution:
[0008] A method for preparing a nickel-cerium oxide coupled heterostructure catalyst, comprising the following steps:
[0009] (1) Add salicylic acid, NaOH, NiCl2·6H2O and Ce(NO3)3·6H2O to a certain amount of deionized water in sequence, and stir for 20 to 40 minutes until completely dissolved;
[0010] (2) Place the mixture obtained in step (1) into a high-pressure reactor and hydrothermally heat it at 100-200℃ for 4-24 hours. After the temperature drops to room temperature, wash it with anhydrous ethanol and deionized water in sequence, and finally put it into an oven to dry at 60-90℃ to obtain the precursor.
[0011] (3) Place the precursor obtained in step (2) into a crucible and calcine it in a tube furnace under an Ar atmosphere at 300-700°C with a heating rate of 2-6°C / min. -1 Keep it warm for 2-4 hours, then let it cool to room temperature;
[0012] (4) The precursor calcined in step (3) is washed with anhydrous ethanol and deionized water in sequence, and then dried in an oven at 60-90°C. The black product is the nickel-cerium oxide coupling and heterogeneous interface structure catalyst.
[0013] Preferably, the concentration of the sodium hydroxide solution in step (1) is 0.1–1 mol / L. -1 .
[0014] Preferably, the amount of salicylic acid added in step (1) is 1 to 10 mmol.
[0015] Preferably, the molar ratio of salicylic acid to NiCl2·6H2O in step (1) is 1:(0.1~2).
[0016] Preferably, the molar ratio of salicylic acid to Ce(NO3)3·6H2O in step (1) is 1:(0.1~2).
[0017] The nickel-cerium oxide coupled heterointerface catalyst prepared by this invention is effective at 10 and 300 mA / cm². -2The overpotentials for HER at the given current densities were 26 and 184 mV, respectively, with a Tafel slope of 62.03 mV dec. -1 Furthermore, it exhibits good stability within 100 hours. The activity and stability of this catalyst for HER are superior to most previously reported non-precious metal materials, and even outperform commercial Pt / C catalysts at industrial-grade current densities.
[0018] The beneficial effects of this invention are:
[0019] (1) In the nickel-cerium oxide coupled heterostructure catalyst prepared by the present invention, nickel and cerium oxide will form a heterostructure interface, increasing more active sites. At the same time, electron rearrangement will also occur, effectively regulating local conductivity and charge density, accelerating charge transfer, and enhancing the activity of hydrogen evolution reaction in water electrolysis.
[0020] (2) The nickel nanoparticles of different sizes and cerium oxide nanoparticles used in this invention form a rough surface, which makes the catalyst hydrophilic and gas-repellent. This not only accelerates the contact between the catalytic material and the electrolyte solution, but also shortens the residence time of bubbles on the catalyst surface, thereby reducing resistance and enhancing electrocatalytic activity.
[0021] (3) In this invention, cerium oxide has a unique electronic structure and abundant oxygen vacancies, which can promote the adsorption of water and the dissociation of H, accelerate the reaction kinetics, and make the HER catalyst more active and stable than most previously reported non-precious metal materials, and even more so than commercial Pt / C catalysts at industrial-grade current densities. Attached Figure Description
[0023] Figure 1 These are polarization curves of the materials NiCe@C-1, NiCe@C-2, NiCe@C-3, NiCe@C-4, and CeO2@C prepared in Examples 1-4 and Comparative Examples;
[0024] Figure 2 The Tafel slope diagrams are for the materials NiCe@C-1, NiCe@C-2, NiCe@C-3, NiCe@C-4 and CeO2@C prepared in Examples 1-4 and the comparative examples.
[0025] Figure 3 The polarization curves and continuous current density at 100 mA cm⁻² of the NiCe@C⁻² catalyst prepared in Example 2 are shown. -2 Comparison of polarization curves after 100 hours of stability testing;
[0026] Figure 4 The NiCe@C-2 catalyst prepared in Example 2 was tested at 100 mA cm⁻¹. -2Stability test results at current density;
[0027] Figure 5 Here is a scanning electron microscope image of the NiCe@C-2 catalyst prepared in Example 3;
[0028] Figure 6 This is a high-magnification transmission electron microscope image of the NiCe@C-2 catalyst prepared in Example 3. Detailed Implementation
[0029] The present invention will be further described below with reference to specific embodiments.
[0030] Example 1:
[0031] Ni / CeO x The preparation method of the @C composite electrocatalyst specifically includes the following steps:
[0032] (1) Add 10 mmol of salicylic acid, 0.5 g of NaOH, 1 mmol of NiCl2·6H2O and 1 mmol of Ce(NO3)3·6H2O to 50 mL of deionized water and stir for 30 min until completely dissolved;
[0033] (2) The mixture obtained in step (1) was placed in a high-pressure reactor and hydrothermally heated at 100°C for 4 hours. After the temperature dropped to room temperature, it was washed with anhydrous ethanol and deionized water in sequence, and finally placed in an oven to dry at 60°C to obtain the precursor.
[0034] (3) Place the precursor obtained in step (2) into a crucible and calcine it in a tube furnace at 460°C under an Ar atmosphere, with a heating rate of 2°C / min. -1 Keep it warm for 2 hours, then let it cool to room temperature;
[0035] (4) The precursor calcined in step (3) was washed with anhydrous ethanol and deionized water in sequence, and then dried in an oven at 60°C. The black product is the nickel-cerium oxide coupling and heterostructure catalyst, which is named NiCe@C-1.
[0036] Example 2:
[0037] Ni / CeO x The preparation method of the @C composite electrocatalyst specifically includes the following steps:
[0038] (1) Add 10 mmol of salicylic acid, 0.5 g of NaOH, 1 mmol of NiCl2·6H2O and 3 mmol of Ce(NO3)3·6H2O to 50 mL of deionized water and stir for 30 min until completely dissolved;
[0039] (2) The mixture obtained in step (1) was placed in a high-pressure reactor and hydrothermally heated at 130°C for 14 hours. After the temperature dropped to room temperature, it was washed with anhydrous ethanol and deionized water in sequence, and finally placed in an oven to dry at 60°C to obtain the precursor.
[0040] (3) Place the precursor obtained in step (2) into a crucible and calcine it in a tube furnace at 550°C under an Ar atmosphere, with a heating rate of 3°C / min. -1 Keep it warm for 3 hours, then let it cool to room temperature;
[0041] (4) The precursor calcined in step (3) is washed with anhydrous ethanol and deionized water in sequence, and then dried in an oven at 60°C. The black product is the nickel-cerium oxide coupling and heterostructure catalyst, which is named NiCe@C-2.
[0042] Example 3:
[0043] Ni / CeO x The preparation method of the @C composite electrocatalyst specifically includes the following steps:
[0044] (1) Add 10 mmol of salicylic acid, 0.5 g of NaOH, 1 mmol of NiCl2·6H2O and 5 mmol of Ce(NO3)3·6H2O to 50 mL of deionized water and stir for 30 min until completely dissolved;
[0045] (2) The mixture obtained in step (1) is placed in a high-pressure reactor and hydrothermally heated at 180°C for 18 hours. After the temperature drops to room temperature, it is washed with anhydrous ethanol and deionized water in sequence, and finally placed in an oven to dry at 60°C to obtain the precursor.
[0046] (3) Place the precursor obtained in step (2) into a crucible and calcine it in a tube furnace at 600°C under an Ar atmosphere, with a heating rate of 5°C / min. -1 Keep it warm for 4 hours, then let it cool to room temperature;
[0047] (4) The precursor calcined in step (3) is washed with anhydrous ethanol and deionized water in sequence, and then dried in an oven at 60°C. The black product is the nickel-cerium oxide coupling and heterostructure catalyst, which is named NiCe@C-3.
[0048] Example 4:
[0049] Ni / CeO x The preparation method of the @C composite electrocatalyst specifically includes the following steps:
[0050] (1) Add 10 mmol of salicylic acid, 0.5 g of NaOH, 2 mmol of NiCl2·6H2O and 5 mmol of Ce(NO3)3·6H2O to 50 mL of deionized water and stir for 30 min until completely dissolved;
[0051] (2) The mixture obtained in step (1) is placed in a high-pressure reactor and hydrothermally heated at 200°C for 24 hours. After the temperature drops to room temperature, it is washed with anhydrous ethanol and deionized water in sequence, and finally placed in an oven to dry at 60°C to obtain the precursor.
[0052] (3) Place the precursor obtained in step (2) into a crucible and calcine it in a tube furnace at 650°C under an Ar atmosphere, with a heating rate of 6°C / min. -1 Keep it warm for 4 hours, then let it cool to room temperature;
[0053] (4) The precursor calcined in step (3) is washed with anhydrous ethanol and deionized water in sequence, and then dried in an oven at 60°C. The black product is the nickel-cerium oxide coupling and heterostructure catalyst, which is named NiCe@C-4.
[0054] Comparative Example:
[0055] CeO x The preparation method of the @C composite electrocatalyst specifically includes the following steps:
[0056] (1) Add 10 mmol of salicylic acid, 0.5 g of NaOH and 3 mmol of Ce(NO3)3·6H2O to 50 mL of deionized water and stir for 30 min until completely dissolved;
[0057] (2) The mixture obtained in step (1) was placed in a high-pressure reactor and hydrothermally heated at 130°C for 14 hours. After the temperature dropped to room temperature, it was washed with anhydrous ethanol and deionized water in sequence, and finally placed in an oven and dried at 60°C to obtain the precursor.
[0058] (3) Place the precursor obtained in step (2) into a crucible and calcine it in a tube furnace at 550°C under an Ar atmosphere, with a heating rate of 3°C / min. -1 Keep it warm for 3 hours, then let it cool to room temperature;
[0059] (4) The calcined precursor from step (3) was washed sequentially with anhydrous ethanol and deionized water, and then dried in an oven at 60°C. The black product was the nickel-cerium oxide coupling and heterostructure catalyst, which was named CeO. x @C.
[0060] Table 1
[0061]
[0062] Table 1 describes the performance of the materials NiCe@C-1, NiCe@C-2, NiCe@C-3, NiCe@C-4, and CeO2@C prepared in Examples 1-4 and the Comparative Examples at 10 and 100 mA cm⁻¹. -2 Overpotential and Tafel slope at time.
[0063] Electrochemical tests were performed on the materials NiCe@C-1, NiCe@C-2, NiCe@C-3, NiCe@C-4, and CeO2@C prepared in Examples 1-4 and the comparative examples. The obtained polarization curves are shown below. Figure 1 As shown, the Tafel slope is as follows Figure 2 As shown, the polarization curves before and after the stability test are as follows: Figure 3 As shown, the stability test curve is as follows: Figure 4 As shown.
[0064] from Figure 1 The overpotentials (current density of 10 mA cm⁻¹) of NiCe@C⁻¹, NiCe@C⁻², NiCe@C⁻³, NiCe@C⁻⁴, and CeO₂@C can be observed. -2 The overpotential of NiCe@C-2 is lower than that of CeO2@C catalyst, especially the overpotential of NiCe@C-2, which is as low as 26mV, which is better than most transition metal compounds.
[0065] from Figure 2 It can be seen that the Tafel slope of the NiCe@C-2 catalyst is relatively low, at 62.03 mV dec. -1 The coefficient of performance is similar to that of Pt / C catalysts, but smaller than that of CeO2@C and other proportions of NiCe@C catalysts. The smaller Tafel slope indicates that NiCe@C-2 effectively accelerates the basic HER kinetics, resulting in a faster electron transfer rate.
[0066] The linear sweep voltammetry curve of the NiCe@C-2 catalyst prepared in Example 2 is shown below. Figure 3 As shown, at a continuous current density of 100 mA cm⁻¹ -2 The polarization curve after 100 hours of stability testing almost overlapped with the initial curve, indicating that the material also has extremely high stability.
[0067] The NiCe@C-2 catalyst prepared in Example 2 was tested for the change of current density over time under constant voltage, as shown below. Figure 4 As shown, during the 100-hour test, the catalyst operated stably at approximately 100 mA cm⁻¹. -2 The current density loss is only about 2.4%.
[0068] Scanning electron microscope (SEM) image of the NiCe@C-2 catalyst prepared in Example 2 is shown below. Figure 5As shown in the SEM images, the NiCe@C-2 catalyst exhibits an interweaving of two different sized nanoparticles, with the smaller nanoparticles being CeO₂. x .
[0069] Example 2: High-magnification transmission electron microscopy image of the NiCe@C-2 catalyst prepared as shown below. Figure 6 As shown in the HR-TEM results, nanoparticles were observed to be encapsulated in a carbon layer, and there was a clear contact between the CeO2 and Ni interfaces, forming a heterogeneous interface, indicating the successful preparation of Ni / CeO2. x @C catalyst materials.
Claims
1. A heterostructure catalyst with a nickel-cerium oxide coupling interface, characterized in that, Synthetic Ni / CeO x @C catalysts possess abundant active sites and unique hydrophilic and gas-phobic structures, making them highly active and stable alkaline high-current HER electrocatalysts.
2. The method for preparing the nickel-cerium oxide coupled heterostructure catalyst according to claim 1, characterized in that... The method is performed in the following steps: (1) Add salicylic acid, NaOH, NiCl2·6H2O and Ce(NO3)3·6H2O to a certain amount of deionized water in sequence, and stir for 20 to 40 minutes until completely dissolved; (2) Place the mixture obtained in step (1) into a high-pressure reactor and hydrothermally heat it at 100-200℃ for 4-24 hours. After the temperature drops to room temperature, wash it with anhydrous ethanol and deionized water in sequence, and finally put it into an oven to dry at 60-90℃ to obtain the precursor. (3) Place the precursor obtained in step (2) into a crucible and calcine it in a tube furnace under an Ar atmosphere at 300-700°C with a heating rate of 2-6°C / min. -1 Keep it warm for 2-4 hours, then let it cool to room temperature; (4) The precursor calcined in step (3) is washed with anhydrous ethanol and deionized water in sequence, and then dried in an oven at 60-90°C. The black product is the nickel-cerium oxide coupling and heterogeneous interface structure catalyst.
3. The method for preparing a nickel-cerium oxide coupled heterostructure catalyst according to claim 2, characterized in that, The concentration of the sodium hydroxide solution mentioned in step (1) is 0.1 to 1 M.
4. The method for preparing a nickel-cerium oxide coupled heterostructure catalyst according to claim 2 or 3, characterized in that, The amount of salicylic acid added in step (1) is 1 to 10 mmol.
5. The method for preparing a nickel-cerium oxide coupled heterostructure catalyst according to claim 2 or 3, characterized in that, In step (1), the molar ratio of salicylic acid to NiCl2·6H2O is 1:(0.1~2).
6. The method for preparing a nickel-cerium oxide coupled heterostructure catalyst according to claim 2 or 3, characterized in that, In step (1), the molar ratio of salicylic acid to Ce(NO3)3·6H2O is 1:(0.1~2).