Nickel-based catalyst as well as preparation method and application thereof
By forming a nickel-based catalyst with a heterostructure of Ni3S2 and Ni9S8 by a one-step hydrothermal method on foam nickel, the problems of high energy loss and insufficient catalytic activity of existing electrocatalysts during water electrolysis are solved, and catalytic effects with high activity, stability and low cost are achieved.
Patent Information
- Application Number
- CN202411457851.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-18
- Publication Date
- 2025-02-25
Smart Images
Figure BDA0005090987350000031 
Figure BDA0005090987350000041 
Figure HDA0005090987360000011
Abstract
Description
Technical Field
[0001] The invention relates to hydrogen production by electrolyzing water, and in particular to a nickel-based catalyst and a preparation method and application thereof. Background Art
[0002] Water electrolysis technology is regarded as one of the most promising green energy conversion methods because it can effectively use renewable energy to generate electricity. Through water electrolysis, hydrogen can be extracted directly from the water source, which provides a clean and sustainable energy path, unlike the traditional reliance on fossil fuels, biomass or a mixture of them. However, one of the main challenges facing water electrolysis is the high energy loss during the reaction, which mainly stems from the limitation of reaction kinetics. In response to this challenge, the research focus in recent years has been on the development of new electrocatalysts to improve the efficiency of water electrolysis. In particular, non-precious metal compounds have received increasing attention as an alternative to traditional precious metal-based catalysts. These materials are not only lower in cost, but also show similar or even better catalytic performance in some cases.
[0003] To date, a large number of non-precious metal compound electrocatalysts have been studied to reduce the overpotential of the oxygen evolution reaction (OER). Among the numerous non-precious metal oxide compounds, nickel sulfide has the characteristics of low cost, easy synthesis, multivalent state change, and high stability in alkaline solution. However, single nickel sulfide has the disadvantages of poor conductivity and insufficient catalytic activity, which limits its application.
[0004] At present, electrocatalytic OER catalysts generally use precious metal oxides such as IrO2 and RuO2. Precious metal catalysts have high reaction activity, but poor long-term stability. In addition, the scarce resources and high prices of precious metals severely limit their large-scale application. Therefore, the research on non-precious metal compounds has developed rapidly. Nickel sulfide, as a representative of this type of catalyst, has attracted widespread attention due to its good catalytic activity and stability in the process of water electrolysis.
[0005] Nickel sulfide has been shown to effectively promote hydrogen evolution reaction and oxygen evolution reaction in the application of electrocatalytic water splitting, which is crucial to improving the energy efficiency of overall water splitting. Non-precious metal catalysts represented by single nickel sulfide are low-cost and easy to synthesize, but they also have defects such as poor conductivity and insufficient catalytic activity. Summary of the invention
[0006] Purpose of the invention: The purpose of the present invention is to provide a nickel-based catalyst with low cost, high activity and high stability, and a preparation method and application thereof.
[0007] Technical solution: The nickel-based catalyst described in the present invention comprises a foamed nickel substrate material, on which nanoparticles are arranged. The nickel-based catalyst has a heterogeneous structure formed by Ni3S2 and Ni9S8.
[0008] Preferably, the heterostructure is prepared by a one-step hydrothermal method.
[0009] The method for preparing the nickel-based catalyst of the present invention comprises the following steps:
[0010] (1) Pre-treating nickel foam to remove surface impurities;
[0011] (2) adding a sulfur precursor to deionized water, and then adding a cobalt precursor, and stirring until dissolved to obtain a solution;
[0012] (3) transferring the solution in step (2) into a reaction kettle, inserting the nickel foam obtained in step (1) into the reaction kettle, and performing a hydrothermal reaction;
[0013] (4) After the reaction is completed, the nickel foam is cooled to room temperature and cleaned and dried.
[0014] Preferably, the sulfur precursor in step (2) is one or two of cysteine, thioacetamide and glutcysteine.
[0015] Preferably, the molar concentration of the sulfur precursor in step (2) in deionized water is in the range of 2.0-3.0 mmol / mL, more preferably 2.5 mmol / mL.
[0016] Preferably, the cobalt precursor in step (2) is one or two of cobalt nitrate hexahydrate, cobalt chloride, and cobalt acetylacetonate.
[0017] Preferably, the molar concentration of the cobalt precursor in step (2) in deionized water is in the range of 0.1-0.8 mmol / mL, more preferably 0.5 mmol / mL.
[0018] Preferably, the stirring temperature in step (2) is 60-80°C, preferably 60°C; the stirring time is 120-160 min, preferably 120 min.
[0019] Preferably, the temperature range of the hydrothermal reaction in step (3) is 100-160° C., preferably 120° C.; the time of the hydrothermal reaction is 10-15 h, preferably 12 h.
[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) In the nickel-based catalyst prepared by the present invention, two valence states of nickel sulfide compounds coexist, and the heterogeneous structure formed by the two compounds is conducive to enhancing the electrode oxygen evolution activity and stability, and has the prospect of industrial application; (2) By constructing a heterojunction and coupling with the cobalt element, the electronic structure of the catalyst can be optimized and its intrinsic catalytic activity can be improved; (3) The present invention adopts a one-step hydrothermal method to prepare the catalyst, without the need to use other processes such as tubular furnace calcination, and the preparation method is simple and cost-saving; (4) Through the one-step hydrothermal method, a catalyst composed of nanoparticles is directly grown on a three-dimensional porous nickel foam, and the preparation method is simple and the conditions are mild; (5) The present invention loads the catalyst on the nickel foam, and the direct coupling of the composite nickel sulfide-based catalyst and the nickel foam reduces the resistance between the active substance and the substrate, providing a fast channel for charge transfer to be connected to each other; (6) The preparation method of the present invention has a wide source of raw materials and low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 TEM image of the catalyst prepared in Example 1;
[0022] Figure 2 LSV curves of the catalysts prepared in Examples 1-3 and Example 8;
[0023] Figure 3 The catalyst prepared in Example 1 was 2 it curve under current density. DETAILED DESCRIPTION
[0024] The technical solution of the present invention is further described below in conjunction with embodiments.
[0025] Example 1
[0026] The method for preparing the nickel-based catalyst of the present invention comprises the following steps:
[0027] (1) Place a nickel foam of 2*3*0.15 cm in a beaker containing acetone, 3M HCl, ethanol and water solution and ultrasonically clean it for 15 min to remove oil, impurities and oxides on the surface of the nickel foam. Then, dry the nickel foam after ultrasonic cleaning in a vacuum drying oven at 60°C for 3 hours and it can be used in subsequent experiments.
[0028] (2) 0.05 mol of cysteine was added to 20 ml of deionized water, followed by 0.01 mol of cobalt nitrate hexahydrate; the mixture was placed on a magnetic stirrer and stirred at 80° C. for 120 min until the solid in the solution dissolved.
[0029] (3) The solution in step (2) is transferred to a reaction kettle whose liner is polytetrafluoroethylene, the nickel foam pretreated in step (1) is inserted obliquely into the polytetrafluoroethylene liner, and a forced air drying oven is set at 120° C. and operated for 12 h to carry out a hydrothermal reaction.
[0030] (4) After the hydrothermal reaction is completed, the mixture is cooled to room temperature; the nickel foam is taken out, rinsed with deionized water several times, and then placed in a drying oven at 60°C for 6 hours for subsequent testing. The catalyst Co-Ni3S2 / Ni9S8-NF is obtained.
[0031] The catalyst was electrochemically tested using a three-electrode system to form LSV curves of different catalysts. First, the nickel foam loaded with the catalyst was cut into a size of 1*1*0.15cm, and the electrode area was 1cm 2 The catalyst was used as the working electrode, the platinum sheet as the counter electrode, Hg / HgO as the reference electrode, 1 M KOH as the electrolyte solution, and the test temperature was 25 °C.
[0032] Embodiment 2-7
[0033] According to the experimental method of Example 1, the reaction conditions were changed to set Examples 2-7. The specific reaction conditions were the same as the catalyst prepared at a current density of 10 mA / cm -2 The overpotentials are shown in Table 1.
[0034] Table 1 Reaction conditions and results of Examples 1-7
[0035]
[0036] Example 8
[0037] The same parts of this embodiment as those of Embodiment 1 are not described in detail, except that:
[0038] In step (2), cobalt nitrate hexahydrate was not added to study the effect of the addition of the cobalt precursor on the experimental results.
[0039] Comparative Examples 1-4
[0040] The key parameters in the hydrothermal reaction were adjusted to explore the effects of temperature and time on the OER performance of the catalyst. According to the experimental method of Example 1, the reaction conditions were changed to set comparative examples 1-4. The specific reaction conditions were the same as the catalyst prepared at a current density of 10 mA / cm -2 The overpotentials are shown in Table 2.
[0041] Table 2 Reaction conditions and results of comparative examples 1-4
[0042]
[0043] Crystal phase analysis of catalyst examples 1-3 and example 8 was performed by X-ray photoelectron spectroscopy. There are obvious diffraction peaks at 2θ of 22.5°, 31.8°, 38.45°, 50.53° and 56°, corresponding to the (101), (110), (003), (113), (122) crystal planes of Ni3S2 (JCPDS 44-1418), proving the successful synthesis of Ni3S2. In addition, these catalysts also have absorption peaks at 2θ of 15.4°, 27.1°, 35.2° and example 53.2°, corresponding to the (111), (202), (312), (261) crystal planes of Ni9S8, proving the successful synthesis of Ni9S8. This provides a basis for the coexistence of Ni3S2 and Ni9S8.
[0044] Figure 2 The LSV curves of the catalysts prepared in Examples 1-3 and Example 8. Figure 2 It can be seen that at a current density of 10 mA cm -2 When the overpotential of the catalysts prepared in Examples 1-3 and 8 is 190mV, 243mV, 249mV, and 278mV, respectively. Comparing Examples 2 and 8, it can be seen that the presence of cobalt is beneficial to the OER reaction; according to the experimental conditions and results of Examples 1-3, it can be seen that the catalyst prepared by using cysteine as a sulfur precursor instead of a traditional sulfur source has the best catalytic effect on the OER reaction, and can reduce the odor in the preparation process to protect the environment. At the same time, the heterojunction formed is more conducive to the transfer of electrons, achieving a better catalytic effect.
[0045] The performance of the catalyst is very important in the reaction. When the catalyst is used in actual industrial production, stability is an essential factor in examining the comprehensive performance of the catalyst. Therefore, the catalyst prepared in Example 1 was subjected to a long-term stability test in 1M KOH electrolyte solution. Figure 3 As shown. At 100mAcm -2 The current density was maintained stably for 48 hours. The test proved that the prepared Co-Ni3S2 / Ni9S8-NF catalyst has strong catalytic stability and excellent commercial application prospects.
[0046] Comparative Example 5
[0047] The similarities between this comparative example and Example 1 are not repeated here, except that elemental sulfur is used as the sulfur precursor.
[0048] By performing XRD test on the catalyst obtained in Comparative Example 5, it was observed that only a single Ni3S2 phase existed. The experiment was carried out under the same test environment as Example 1, at 10 mA / cm -2 The overpotential of the comparative example 5 is 268 mV, which is much higher than that of the embodiment 1.
[0049] By comparing Example 1 with Comparative Example 5, it can be found that the heterostructure formed by Ni3S2 and Ni9S8 in the present technical solution has unique advantages, which proves the important role of the heterostructure in water electrolysis and also illustrates the advantages of the present technical solution.
Claims
1. A nickel-based catalyst, characterized in that The invention comprises a foam nickel substrate material, on which nanometer particles are arranged. The nickel-based catalyst has a heterogeneous structure formed by Ni3S2 and Ni9S8.
2. The nickel-based catalyst according to claim 1, characterized in that The heterogeneous structure is prepared by a one-step hydrothermal method.
3. A method for preparing the nickel-based catalyst according to claim 1, characterized in that: The following steps are involved: (1) Pre-treating nickel foam to remove surface impurities; (2) adding a sulfur precursor to deionized water, and then adding a cobalt precursor, stirring until dissolved to obtain a mixed solution; (3) transferring the mixed solution in step (2) into a reaction kettle, inserting the nickel foam obtained in step (1) into the reaction kettle, and performing a hydrothermal reaction; (4) After the reaction is completed, the nickel foam is cooled to room temperature and cleaned and dried.
4. The preparation method according to claim 3, characterized in that: The sulfur precursor in step (2) is one or two of cysteine, thioacetamide and glutcysteine.
5. The preparation method according to claim 3, characterized in that: The molar concentration of the sulfur precursor in step (2) in deionized water is in the range of 2.0-3.0 mmol / mL.
6. The preparation method according to claim 3, characterized in that: The cobalt precursor in step (2) is one or two of cobalt nitrate hexahydrate, cobalt chloride, and cobalt acetylacetonate.
7. The preparation method according to claim 3, characterized in that: The molar concentration range of the cobalt precursor in deionized water is 0.1-0.8 mmol / mL.
8. The preparation method according to claim 3, characterized in that: The stirring temperature in step (2) is 60-80° C. and the stirring time is 120-160 min.
9. The preparation method according to claim 3, characterized in that: The temperature of the hydrothermal reaction in step (3) is 100-160° C., and the time of the hydrothermal reaction is 10-15 h.
10. The preparation method according to claim 3, characterized in that: The temperature of the hydrothermal reaction in step (3) is 120° C., and the time of the hydrothermal reaction is 12 h.