Preparation method and application of oxygen-enriched carbon confinement nickel nanosheet electrode material

Abstract

The invention belongs to the field of new energy electro-catalytic materials, and particularly relates to a preparation method and application of an oxygen-enriched carbon confinement nickel nanosheet electrode material.The preparation method comprises the steps that S1, nickel salt and terephthalic acid are dissolved in a mixed solvent of deionized water, ethyl alcohol and N, N-dimethylformamide, and a precursor solution is obtained; s2, a foamed nickel substrate is placed in the precursor solution obtained in the step S1 for a one-step hydrothermal reaction, and a nickel-based metal organic framework nanosheet precursor is obtained after washing and drying treatment; and S3, performing high-temperature pyrolysis and carbonization on the precursor obtained in the step S2 in an inert atmosphere to obtain the oxygen-enriched carbon confinement nickel nanosheet electrode material. The invention also provides an application of the oxygen-enriched carbon confinement nickel nanosheet electrode material prepared by the preparation method in electrocatalytic water desorption hydrogen evolution in an alkaline electrolyte. The catalytic material shows excellent electro-catalytic hydrogen evolution activity and good catalytic stability in an alkaline electrolyte.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy electrocatalytic materials, and in particular to a preparation method and application of an oxygen-rich carbon-confined nickel nanosheet electrode material. Background Art

[0002] Due to the depletion of fossil fuels and the pollution they cause to the environment, the development of renewable clean energy is urgent. Hydrogen energy is considered to be one of the most ideal alternative energy sources due to its advantages such as zero combustion emissions, renewability, and high energy density. The use of renewable electricity to produce green hydrogen is a key electrochemical technology to promote the development of energy transformation. However, the high price of precious metal platinum-based catalysts required for the hydrogen evolution half-reaction in water electrolysis technology has hindered its industrial development. Therefore, it is urgent to develop non-precious metal-based electrocatalysts with excellent catalytic activity and low cost.

[0003] In recent years, due to the large reserves of non-precious metal nickel-based catalysts, low prices, good conductivity and high activity, they have been widely studied and developed as catalysts for hydrogen evolution by electrolysis of water. For example, the Chinese patent document with publication number CN110129825A discloses a highly efficient Ni / Ni(OH) 2 A method for preparing a hydrogen evolution electrode, which uses nickel sulfate hexahydrate and nickel chloride as nickel element sources, and prepares a highly efficient Ni / Ni(OH) 2 Hydrogen evolution electrode. For example, publication number CN119352067A discloses a method for preparing a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst, which comprises hydrothermal reaction of a nickel source, a molybdenum source and nickel foam, landfilling with urea, and calcining at high temperature and in a nitrogen atmosphere to obtain a carbon-nitrogen encapsulated nickel-based binary metal hydrogen evolution catalyst.

[0004] However, the current research on the microstructure regulation of nickel-based hydrogen evolution catalysts is still relatively limited, resulting in its hydrogen evolution activity being difficult to match that of precious metal platinum-based catalysts. Metal-organic framework (MOF) materials are a type of inorganic-organic polymer material with rich adjustable coordination environment and pore structure. If used as a catalyst precursor, it can be prepared into structurally adjustable nickel-based nanocarbon catalysts through high-temperature pyrolysis and carbonization. By effectively optimizing the coordination environment and electronic structure of the metal nickel material, the rate-controlled water activation step of the alkaline hydrogen evolution reaction is accelerated, thereby improving the electrocatalytic hydrogen evolution activity of the nickel-based catalyst, which is of great significance for promoting the progress of hydrogen production technology by electrolysis of water.

[0005] In view of the above problems, the present invention document proposes a preparation method and application of oxygen-rich carbon-confined nickel nanosheet electrode material to solve the above problems. Summary of the invention

[0006] The invention provides a preparation method of an oxygen-rich carbon-confined nickel nanosheet electrode material and application thereof, which solves the shortcomings of the prior art.

[0007] The present invention provides the following technical solutions:

[0008] A method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material comprises: the preparation method comprises the following steps:

[0009] S1, dissolving nickel salt and terephthalic acid in a mixed solvent of deionized water, ethanol and N,N-dimethylformamide to obtain a precursor solution;

[0010] S2, placing the nickel foam substrate in the precursor solution obtained in step S1, performing a one-step hydrothermal reaction, and then washing and drying to obtain a nickel-based metal organic framework nanosheet precursor;

[0011] S3, subjecting the precursor obtained in step S2 to high-temperature pyrolysis and carbonization under an inert atmosphere to obtain the oxygen-rich carbon-confined nickel nanosheet electrode material.

[0012] In a possible design, the mass concentration of the nickel salt in the precursor solution is 20-30 g / L.

[0013] In a possible design, the mass concentration of terephthalic acid in the precursor solution is 12-18 g / L.

[0014] In a possible design, the temperature of the hydrothermal reaction is 100-140° C., and the reaction time is 6-16 hours.

[0015] In a possible design, the high temperature pyrolysis temperature is 400-600° C., and the pyrolysis time is 1-3 hours.

[0016] An application of the oxygen-rich carbon-confined nickel nanosheet electrode material as described above, wherein the oxygen-rich carbon-confined nickel nanosheet electrode material is used as a working electrode in an electrocatalytic water-to-hydrogen separation reaction in an alkaline electrolyte.

[0017] It is to be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the invention.

[0018] The beneficial effects of the present invention are:

[0019] (1) The oxygen-rich carbon-confined nickel nanosheet electrode material provided by the present invention has both high electrocatalytic activity and stability in the electrolysis of water and hydrogen evolution in alkaline electrolyte. -2 When the cathode overpotential is 215 mV, it can be maintained for 24 hours without obvious potential decay, which provides the possibility for further improving the development and utilization of hydrogen energy.

[0020] (2) The oxygen-rich carbon-confined nickel nanosheet electrode material provided by the present invention in situ grows oxygen-rich porous carbon-confined nickel nanosheets with a microscopic two-dimensional array morphology on a three-dimensional nickel foam conductive substrate, which can effectively expose more reactive sites, enhance reaction mass transfer, and reduce reaction resistance, thereby accelerating the kinetics of the electrocatalytic hydrogen evolution reaction;

[0021] (3) The oxygen-rich carbon-confined nickel nanosheet electrode material provided by the present invention optimizes the coordination environment of the metal nickel material through the confinement effect of the oxygen-rich porous carbon, affects its electronic structure, accelerates the adsorption and activation of the corresponding water molecules of the material, and ultimately improves the rate of the electrocatalytic hydrogen evolution reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A scanning electron microscope image of a Ni@OC material prepared in Example 1 of a method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material and its application provided in an embodiment of the present invention;

[0023] Figure 2 A transmission electron microscope image of a Ni@OC material prepared in Example 1 of a method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material and its application provided in an embodiment of the present invention;

[0024] Figure 3 X-ray diffraction pattern of Ni@OC material prepared in Example 1 of a method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material and its application provided in an embodiment of the present invention;

[0025] Figure 4 Raman spectra of materials prepared in Example 1 and Comparative Example 1 of a method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material and its application provided in an embodiment of the present invention;

[0026] Figure 5 Polarization curves of the materials prepared in Example 1 and Comparative Examples 1-2 of a method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material and its application in the application examples provided by the present invention for electrocatalytic hydrogen evolution;

[0027] Figure 6 This is a stability test chart of the Ni@OC material for electrocatalytic hydrogen evolution prepared in Example 1 of a method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material and its application provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0029] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms, "connection" and "installation" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. In addition, "connection" can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed" means that they are connected to each other and the relative position relationship after connection remains unchanged. The directional terms mentioned in the embodiments of the present invention, such as "inside", "outside", "top", "bottom", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0030] In the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0031] In the embodiments of the present invention, "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0032] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present invention. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. appearing in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0033] Example 1

[0034] Reference Figure 1-6 , a preparation method and application of an oxygen-rich carbon-confined nickel nanosheet electrode material, comprising:

[0035] S1. Weigh 930 mg of nickel nitrate hexahydrate solid particles and 498 mg of terephthalic acid solid particles, dissolve them in a mixed solvent of 2.5 mL of ethanol, 2.5 mL of deionized water and 30 mL of DMF, and stir at room temperature for 20 min until they are completely dissolved to obtain a green clear solution;

[0036] S2. Place the nickel foam in the clarified solution obtained in step S1, transfer it to a hydrothermal kettle, heat it to 120°C and maintain it for 12 hours. After the reaction is completed, naturally cool it to room temperature, take out the electrode material, wash it with ethanol and water several times, and dry it in an oven at 60°C for 4 hours to obtain a nickel-based metal organic framework nanosheet precursor.

[0037] S3. Place the nickel-based metal organic framework nanosheet precursor in a tubular furnace for high-temperature pyrolysis and carbonization in an argon atmosphere, raise the temperature to 450°C and keep it for 2 hours, and cool it to room temperature to obtain oxygen-rich carbon-confined nickel nanosheet electrode material (Ni@OC).

[0038] Figure 1 This is a scanning electron microscope image of the oxygen-rich carbon-confined nickel nanosheet electrode material prepared in this example. Figure 2 This is a transmission electron microscope image of the oxygen-rich carbon-confined nickel nanosheet electrode material prepared in this example. Figures 1-2 It can be seen that the obtained electrode material has a two-dimensional porous nanosheet array morphology. The X-ray diffraction pattern of the oxygen-rich carbon-confined nickel nanosheet electrode material prepared in this embodiment is as follows: Figure 3 As shown, the diffraction peak at 25.7° corresponds to the porous carbon support, and the peaks at 44.4°, 51.7°, and 76.4° correspond to the (111), (200), and (220) crystal planes of Ni metal, respectively. Figure 4 is the Raman spectrum of the material, and it can be seen that the oxygen-rich carbon-confined nickel nanosheet electrode material prepared in this embodiment has a rich nickel-oxygen bonding coordination structure.

[0039] Comparative Example 1

[0040] The process of Example 1 is the same as that of Example 1, except that during the high-temperature pyrolysis carbonization in step (3), the atmosphere is changed to 5% H 2 / Ar mixed gas to obtain nickel-carbon electrode material (Ni@C).

[0041] Comparative Example 2

[0042] The process of Example 1 is followed, except that step (3) is not performed, to obtain a nickel-based metal organic framework nanosheet electrode material (Ni-MOF).

[0043] Application Examples

[0044] (1) A three-electrode system was used, with the electrode material prepared in Example 1 or Comparative Examples 1-2 as the working electrode, the counter electrode being a carbon rod, the reference electrode being a Hg / HgO electrode, and the electrolyte being 1 M KOH;

[0045] (2) Shanghai Chenhua CHI 760E electrochemical workstation was used. Nitrogen was introduced into the electrolyte for 20 min before the test. The CV program was used with a test interval of 0.1 to -1.6 V vs. reversible hydrogen electrode (RHE) and a scan rate of 50 mV s -1 , 20 cycles, so that the catalytic material reaches a stable state. The electrode materials prepared in Example 1 and Comparative Examples 1-2 were subjected to linear sweep voltammetry (LSV) testing. After CV activation, the program was switched to the LSV program, the test range was 0.1 to -1.6 V vs. RHE, the sweep rate was 5 mV / s, and the overpotential was the difference between the potential measured at 0 V relative to the reversible hydrogen electrode and at different current densities. The polarization curves of the electrode materials provided in Example 1 and Comparative Examples 1-2 for electrocatalytic hydrogen evolution in 1 M KOH solution are shown in the figure below. Figure 5 As shown, from Figure 5 It can be seen that in alkaline electrolyte, the oxygen-rich carbon-confined nickel nanosheet electrode material (Ni@OC) prepared in Example 1 has good electrocatalytic hydrogen evolution activity, and the current density of the electrode material in Example 1 reaches 1000 mA cm -2 The overpotential is only 215 mV, and the catalytic performance is significantly better than that of nickel-carbon electrode materials (Ni@C) and nickel-based metal organic framework nanosheet electrode materials (Ni-MOF).

[0046] The stability test of the electrode material prepared in Example 1

[0047] After CV activation, switch the program to ISTEP program, set the current to -1A, and the time to 86400s. Figure 6 As shown, the potential of the oxygen-rich carbon-confined nickel nanosheet electrode material (Ni@OC) did not change much over time, demonstrating its superior catalytic stability.

[0048] The working principle and use process of this technical solution are as follows: using terephthalic acid as an oxygen-containing organic ligand, during the hydrothermal growth process, divalent nickel ions and the carboxyl functional groups of terephthalic acid undergo coordination self-assembly, and in-situ growth of nickel-based metal organic framework nanosheet electrode materials on a conductive substrate. The precursor is then calcined at high temperature, during which the oxygen-containing organic ligands are derived to obtain an oxygen-doped carbon matrix, while the nickel metal nodes are aggregated and reduced, and finally an oxygen-rich carbon-confined nickel nanosheet electrode material is obtained.

[0049] This three-dimensional electrode material has a nanosheet array morphology, which can expose more catalytic active sites, and the rich oxygen doping can effectively optimize the electronic structure of nickel, promote the adsorption and activation of water molecules at the active sites, and ultimately enhance the electrocatalytic hydrogen evolution activity of the material.

[0050] The nickel salt in step S1 is a soluble salt selected from nickel chloride, nickel nitrate, nickel sulfate and hydrates thereof. Preferably, the nickel salt is nickel nitrate hexahydrate.

[0051] The stirring time in step S1 is 20 to 60 minutes. Magnetic stirring or ultrasonic dispersion can be used to evenly disperse the nickel salt and terephthalic acid in the mixed solvent.

[0052] In step S1, the mass concentration of the nickel salt is 20-30 g / L, and the mass concentration of terephthalic acid is 12-18 g / L.

[0053] The temperature of the hydrothermal reaction in step S2 is 100-140°C; the time of the hydrothermal reaction is 6-16 hours. This is because the structure of the nickel-based metal organic framework nanosheet array produced is more regular when the temperature and time of the hydrothermal reaction are maintained. If the temperature is too low, the metal organic framework cannot be formed. If the temperature is too high, the reaction is too intense and the metal organic framework nanosheet structure formed will be significantly agglomerated.

[0054] The high temperature pyrolysis temperature in step S3 is 400-600°C, the pyrolysis time is 1-3 hours, and the atmosphere is an inert atmosphere, including nitrogen or argon. If the pyrolysis temperature is too low, the metal organic framework nanosheets cannot be carbonized, and if the pyrolysis temperature is too high, the oxygen doping amount will be significantly reduced, thereby reducing the catalytic activity.

[0055] Preferably, the mixed solvent is water: ethanol: DMF = 1: 1: 12 mL (volume ratio). The mass concentration of nickel salt is 26.5 g / L, the mass concentration of 2,5-thiophenedicarboxylic acid is 14 g / L, and the hydrothermal reaction is maintained at 120 ° C for 12 hours. The temperature of high-temperature pyrolysis is 450 ° C, the pyrolysis time is 2 hours, and the atmosphere is argon. Under these conditions, the prepared oxygen-rich carbon-confined nickel nanosheet electrode material has the highest activity in electrocatalytic water decomposition of hydrogen in alkaline electrolyte.

[0056] The present invention also provides an oxygen-rich carbon-confined nickel nanosheet electrode material (Ni@OC) prepared by the above preparation method. The oxygen-rich carbon-confined nickel nanosheet electrode material has a two-dimensional nanosheet array structure.

[0057] The oxygen-rich carbon-confined nickel nanosheet electrode material provided by the present invention can be used as a working electrode in the cathode hydrogen evolution reaction of water electrolysis in an alkaline electrolyte.

[0058] In the cathode hydrogen evolution reaction of water electrolysis, a three-electrode system is adopted, specifically, a Hg / HgO electrode is used as a reference electrode, a carbon rod is used as a counter electrode, the oxygen-rich carbon confined nickel nanosheet electrode material provided by the present invention is used as a working electrode, and a 1M KOH solution is used as an electrolyte.

[0059] In view of the problem of limited electrocatalytic activity of nickel-based materials in the prior art, the present invention prepares the above-mentioned oxygen-rich carbon-confined nickel nanosheet electrode material through coordination self-assembly coupled with high-temperature pyrolysis and carbonization strategy, which can effectively rationally design the coordination structure of metallic nickel, thereby effectively optimizing its electronic structure. The oxygen-rich carbon-confined nickel nanosheet electrode material provided by the present invention has abundant oxygen-doped species, and enhances the adsorption and activation kinetics of the material for water molecules through nickel-oxygen bonding, and ultimately improves the electrocatalytic hydrogen evolution reaction activity of the material;

[0060] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention; the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for preparing an oxygen-rich carbon-confined nickel nanosheet electrode material, characterized in that: The preparation method comprises the following steps: S1, dissolving nickel salt and terephthalic acid in a mixed solvent of deionized water, ethanol and N,N-dimethylformamide to obtain a precursor solution; S2, placing the nickel foam substrate in the precursor solution obtained in step S1, performing a one-step hydrothermal reaction, and then washing and drying to obtain a nickel-based metal organic framework nanosheet precursor; S3, subjecting the precursor obtained in step S2 to high-temperature pyrolysis and carbonization under an inert atmosphere to obtain the oxygen-rich carbon-confined nickel nanosheet electrode material.

2. The preparation method and application of an oxygen-rich carbon-confined nickel nanosheet electrode material according to claim 1, characterized in that: The mass concentration of nickel salt in the precursor solution is 20-30 g / L.

3. The preparation method and application of an oxygen-rich carbon-confined nickel nanosheet electrode material according to claim 1, characterized in that: The mass concentration of terephthalic acid in the precursor solution is 12-18 g / L.

4. The preparation method and application of an oxygen-rich carbon-confined nickel nanosheet electrode material according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 100-140° C., and the reaction time is 6-16 hours.

5. The preparation method and application of an oxygen-rich carbon-confined nickel nanosheet electrode material according to claim 1, characterized in that: The high temperature pyrolysis temperature is 400-600° C., and the pyrolysis time is 1-3 hours.

6. An application of the oxygen-rich carbon-confined nickel nanosheet electrode material according to any one of claims 1 to 5, characterized in that: The oxygen-rich carbon-confined nickel nanosheet electrode material is used as a working electrode in an electrocatalytic water-to-hydrogen separation reaction in an alkaline electrolyte.

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