Chiral molecule coupling layered hydroxide catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the field of new energy material synthesis and electro-catalysis, and particularly relates to a chiral molecule coupling layered hydroxide catalyst and a preparation method and application thereof. The invention innovatively provides a synergistic strategy fusing chiral molecular engineering and a bionic design principle to improve the oxygen evolution performance of the nickel-iron layered hydroxide, a one-step hydrothermal method is adopted for preparation, controllable anchoring of chiral molecules between layers of the nickel-iron layered hydroxide is realized, and the performance of the nickel-iron layered hydroxide is improved. Chiral molecules with a proton acceptor function are introduced into a NiFe-LDH interlayer; due to the steric hindrance and coordination characteristics of chiral molecules, regular growth of NiFe-LDH laminates can be disrupted, and more lattice defects, edge sites and unsaturated coordination metal centers are induced to be generated. The coordination effect of chiral molecules and metal centers (Ni and Fe) can adjust the electronic state and valence state of metal, so that the reaction energy barrier is reduced, and the reaction kinetics is accelerated.

Description

Technical Field

[0001] This invention belongs to the field of new energy material synthesis and electrocatalysis, specifically relating to a chiral molecularly coupled layered hydroxide catalyst, its preparation method, and its application. Background Technology

[0002] With the depletion of traditional fossil fuels and the resulting environmental pollution posing a significant challenge to sustainable social development, the development of new clean and renewable energy sources has become a crucial issue. Against this backdrop, hydrogen, as a high-energy-density substance, is an ideal future form of fuel. Hydrogen production through water electrolysis plays a vital role in reducing CO2 emissions and promoting energy structure transformation. However, compared to HER (Heterogeneous Evolution), the anodic oxygen evolution reaction (OER) in water electrolysis suffers from an imbalance between fast electron and slow proton transfer, thus controlling the efficiency of OER by a slower proton transfer rate. Simultaneously, during OER, the uncontrolled oxidation process, constrained by spin, leads to higher overpotentials and promotes the kinetically favorable formation of H2O2. This side reaction pathway not only significantly reduces the Faraday efficiency of OER, but more seriously, the generated H2O2, due to its strong oxidizing properties, accelerates the dissolution of the anodic catalyst and erodes the proton exchange membrane, becoming one of the key bottlenecks restricting the industrialization of water electrolysis hydrogen production technology and posing a significant challenge to the advancement of water splitting technology.

[0003] To date, the noble metal RuO2 / IrO2 has been recognized as an excellent OER catalyst material, but its high cost and scarcity of resources limit its widespread application. Therefore, developing electrocatalysts based on inexpensive transition metals is an important research topic in the development of water electrolysis for hydrogen production technology. In recent years, transition metal nickel-iron hydroxide (NiFe-LDH) has been widely regarded as one of the most promising OER electrocatalysts in alkaline electrolysis environments due to its unique two-dimensional layered structure and significant spin-orbit coupling exchange. However, its current performance is still difficult to meet practical production requirements due to the inherent catalytic activity of the material. Furthermore, the continuous dissolution and phase separation of the metal at high current densities cause structural collapse and dissolution of the layered hydroxide, posing significant challenges to its industrial application.

[0004] By precisely designing intercalation layers, guest molecules with specific structures are introduced into the interlayer space of the nickel-iron hydroxide host, simultaneously stabilizing the metal active center and effectively regulating the interlayer spacing, thereby systematically optimizing its catalytic performance. This invention proposes a functionalization design strategy for layered NiFe-LDH catalysts. By combining chirality with a guest intercalation strategy, a synergistic enhancement of spin regulation and proton transfer capability is achieved, significantly improving its oxygen evolution performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a chiral molecularly coupled layered hydroxide catalyst, its preparation method and application. Based on hydrothermal synthesis, the catalyst has a two-dimensional nanosheet structure. The chiral molecular intercalation optimizes the electronic interaction between the metal of the layered hydroxide plates and the interlayer guests. The catalyst exhibits excellent oxygen evolution reaction activity and stability, and significantly improves the overall performance of the water electrolysis system.

[0006] The technical solution adopted is as follows: A method for preparing a chiral molecularly coupled layered hydroxide catalyst includes the following steps: (1) Preparation of precursor solution: Dissolve nickel source, iron source and chiral ligand solid powder in deionized water and stir to form initial solution; The pH of the initial solution was adjusted to 8.0–10.0 using an alkaline adjuster, and the mixture was stirred until homogeneous to form a mixed solution. (2) Hydrothermal reaction: The mixed solution is transferred to a reaction vessel, sealed and heated to obtain chiral molecularly coupled nickel-iron hydroxide; (3) Cleaning and drying: After the hydrothermal reaction is completed, the reaction product is taken out, cleaned, centrifuged, vacuum dried and ground to obtain the chiral molecularly coupled layered hydroxide catalyst (cm-NiFe-LDH, where cm is a chiral molecule).

[0007] Preferably, in step (1), the nickel source is selected from at least one of nickel chloride hexahydrate, nickel nitrate, nickel sulfate, or nickel acetate; the iron source is selected from at least one of ferric chloride nonahydrate, ferric chloride hexahydrate, ferric nitrate, or ferric sulfate; the chiral ligand is at least one of chiral amino acid, chiral amino acid derivative, chiral diamine, or chiral lactic acid; and the total molar ratio of the nickel source, iron source, and chiral ligand is (5~7):(2~4):(2~4).

[0008] Preferably, the nickel source is nickel chloride hexahydrate, the iron source is ferric chloride nonahydrate, and the chiral ligand is L-aspartic acid, L-glutamic acid, L-threonine, or L-isoleucine, and the molar ratio of nickel chloride hexahydrate, ferric chloride nonahydrate, and chiral ligand is (5~6):(2~3):(2~3).

[0009] Preferably, in step (1), the alkalinity regulator is at least one aqueous solution of sodium carbonate, sodium bicarbonate, sodium hydroxide, or ammonia.

[0010] Preferably, after adjustment, the pH value of the mixed solution is adjusted to 8.5–9.0.

[0011] Preferably, in step (2), the reaction vessel is a stainless steel high-pressure reactor, and the mixed solution is transferred to the polytetrafluoroethylene liner of the stainless steel high-pressure reactor; the heating temperature is 110℃~120℃, and the heating time is 8~20 h.

[0012] Preferably, in step (3), the washing and centrifugation method is as follows: wash three times by alternating centrifugation with deionized water and anhydrous ethanol, with a centrifugation speed of 4000~4500 r / min and a single centrifugation time of 3~5 min.

[0013] Preferably, in step (3), vacuum drying is performed at 70~90℃ for 8~16 h; grinding time is 30 min.

[0014] The present invention also provides a method for preparing a chiral molecularly coupled layered hydroxide catalyst, wherein the prepared chiral molecularly coupled layered hydroxide catalyst has a two-dimensional nanosheet structure.

[0015] Another objective of this invention is to provide the application of chiral molecularly coupled layered hydroxide catalysts in the oxygen evolution reaction (OER). Furthermore, it can also be applied to chiral drug and pesticide synthesis, chiral sensing and enantiomeric recognition analysis, fine chemical synthesis, biomedicine, and environmental catalysis.

[0016] The catalyst obtained in this invention possesses a two-dimensional nanosheet structure. In the oxygen evolution reaction (OER), chiral molecular intercalation optimizes the electronic interactions between the metal layers of the layered hydroxide plates and the interlayer guests, stabilizing the metal center; simultaneously, it allows for precise control of the PCET process. Based on this synergistic mechanism, the composite material exhibits excellent OER activity and stability, significantly improving the overall performance of the water electrolysis system.

[0017] The chiral molecularly coupled layered hydroxide catalyst is suitable for various energy conversion and storage devices such as water electrolysis for hydrogen production, metal-air batteries, and fuel cells, and has significant practical application prospects.

[0018] Compared with existing technologies, the significant advantages of this invention are: This invention innovatively proposes a synergistic strategy integrating chiral molecular engineering and biomimetic design principles to enhance the oxygen evolution performance of NiFe-LDH layered hydroxides. This scheme introduces chiral molecules with proton acceptor function into the NiFe-LDH interlayer via a simple and controllable one-step hydrothermal method. The steric hindrance and coordination properties of the chiral molecules disrupt the regular growth of the NiFe-LDH layers, inducing the generation of more lattice defects, edge sites, and unsaturated coordinated metal centers. The coordination interaction between the chiral molecules and the metal centers (Ni, Fe) can regulate the electronic and valence states of the metals, thereby lowering the reaction energy barrier and accelerating reaction kinetics.

[0019] The preparation method and the catalyst prepared in this invention show significant application potential in the field of electrocatalysis. They not only enrich the functional synthesis methodology of layered hydroxides, but also broaden the industrial application prospects for developing high-performance and high-stability water electrolysis catalysts. Attached Figure Description

[0020] Figure 1 This is a TEM image of cm-NiFe-LDH prepared in Example 1.

[0021] Figure 2 This is a scanning electron microscope image of cm-NiFe-LDH prepared in Example 1.

[0022] Figure 3 The images show the X-ray powder diffraction patterns of the cm-NiFe-LDH prepared in Examples 1-4 and the catalyst prepared in Comparative Example 1.

[0023] Figure 4 The images show the FTIR spectra of cm-NiFe-LDH prepared in Examples 1-4 and the catalyst prepared in Comparative Example 1.

[0024] Figure 5 This is a graph showing the electrocatalytic oxygen evolution data of the cm-NiFe-LDH prepared in Example 1 and the catalyst prepared in Comparative Example 1. Detailed Implementation

[0025] The accompanying drawings are for illustrative purposes only; to make the objectives and technical solutions of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. The present invention is not limited to the specific examples and embodiments described herein. Any further improvements and refinements made by those skilled in the art without departing from the spirit and scope of the present invention fall within the protection scope of the present invention, unless otherwise specified. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The reagents used in the present invention are available through conventional commercial channels, and the testing methods and equipment used are conventional methods and equipment in this technical field.

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Example 1 A method for preparing a chiral molecularly coupled layered hydroxide catalyst includes the following steps: (1) Preparation of precursor solution: 6 mmol nickel chloride hexahydrate, 3 mmol ferric chloride nonahydrate and 3 mmol L-aspartic acid solid powder were dissolved in 15 mL deionized water and stirred continuously at room temperature until the powder was completely dissolved and a uniform and stable dark brown liquid was formed in the beaker. The pH of the dark brown liquid was adjusted to 8.5 using sodium carbonate solution, and the mixture was brought to a final volume of 40 mL using deionized water. The mixture was then stirred at a constant speed for 5 min.

[0028] (2) Hydrothermal reaction: The mixed solution was transferred to the polytetrafluoroethylene liner of a 50 mL stainless steel high-pressure reactor and heated at 115 °C for 12 h to obtain chiral amino acid coupled nickel iron hydroxide.

[0029] (3) Cleaning and drying: After the hydrothermal reaction is completed, the reaction product is taken out and washed three times by alternating centrifugation with deionized water and anhydrous ethanol. The centrifugation speed is 4500 r / min and the centrifugation time is 5 min.

[0030] After vacuum drying at 80℃ for 12 hours, the product is thoroughly ground to obtain a chiral molecularly coupled layered hydroxide catalyst (cm-NiFe-LDH, where cm represents a chiral molecule).

[0031] like Figure 1 , Figure 2 The images shown are TEM images and scanning electron microscope images of cm-NiFe-LDH prepared in Example 1, demonstrating the synthesis of chiral amino acid-coupled nickel-iron hydroxide.

[0032] Example 2 A method for preparing a chiral molecularly coupled layered hydroxide catalyst includes the following steps: (1) Preparation of precursor solution: 5 mmol nickel nitrate, 2 mmol ferric nitrate and 2 mmol L-threonine solid powder were dissolved in 10 mL deionized water and stirred continuously at room temperature until the powder was completely dissolved and a uniform and stable dark brown liquid was formed in the beaker. The pH of the dark brown liquid was adjusted to 9 using sodium carbonate solution, and the mixture was brought to a final volume of 35 mL using deionized water. The mixture was then stirred at a constant speed for 5 min.

[0033] (2) Hydrothermal reaction: The mixed solution was transferred to the polytetrafluoroethylene liner of a 50 mL stainless steel high-pressure reactor and heated at 120 °C for 10 h to obtain chiral amino acid coupled nickel-iron hydroxide.

[0034] (3) Cleaning and drying: After the hydrothermal reaction is completed, the reaction product is taken out and washed three times by alternating centrifugation with deionized water and anhydrous ethanol. The centrifugation speed is 4000 r / min and the centrifugation time is 4 min.

[0035] After vacuum drying at 80℃ for 12 hours, the product is thoroughly ground to obtain a chiral molecularly coupled layered hydroxide catalyst (cm-NiFe-LDH, where cm represents a chiral molecule).

[0036] Example 3 A method for preparing a chiral molecularly coupled layered hydroxide catalyst, comprising the preparation of a precursor solution: 5 mmol nickel sulfate, 2 mmol ferric sulfate and 2 mmol L-glutamic acid solid powder dissolved in 10 mL deionized water.

[0037] Other areas not mentioned are the same as in Example 2.

[0038] Example 4 A method for preparing a chiral molecularly coupled layered hydroxide catalyst, comprising the preparation of a precursor solution: 5 mmol nickel sulfate, 2 mmol ferric sulfate and 2 mmol L-isoleucine solid powder dissolved in 10 mL deionized water.

[0039] Other areas not mentioned are the same as in Example 2.

[0040] Comparative Example 1 A method for preparing a layered hydroxide catalyst includes the following steps: (1) Preparation of precursor solution: 6 mmol nickel chloride hexahydrate and 3 mmol ferric chloride nonahydrate were dissolved in 10 mL of deionized water and stirred continuously at room temperature until the powder was completely dissolved; The pH of the dark brown liquid was adjusted to 8.5 using sodium carbonate solution, and the mixture was brought to a final volume of 40 mL using deionized water. The mixture was then stirred at a constant speed for 5 min.

[0041] (2) Hydrothermal reaction: The mixed solution was transferred to the polytetrafluoroethylene liner of a 50 mL stainless steel high-pressure reactor and heated at 115 °C for 12 h to obtain nickel iron hydroxide.

[0042] (3) Cleaning and drying: After the hydrothermal reaction is completed, the reaction product is taken out and washed three times by alternating centrifugation with deionized water and anhydrous ethanol. The centrifugation speed is 4500 r / min and the centrifugation time is 5 min.

[0043] After vacuum drying at 80℃ for 12 hours, the catalyst is thoroughly ground to obtain a layered hydroxide catalyst.

[0044] The cm-NiFe-LDH prepared in Example 1 was compared with the layered hydroxide catalyst prepared in Comparative Example 1.

[0045] like Figure 3 The X-ray powder diffraction patterns of the samples prepared in Examples 1-4 and Comparative Example 1 are shown below. Figure 5 The FTIR spectra of the samples prepared in Examples 1-4 and Comparative Example 1 are shown. By comparing with the standard card of Ni(OH)2, it can be confirmed that the obtained products are all nickel-iron hydroxides. The introduction of chiral molecules does not destroy the intrinsic structure, and the introduction of chiral amino acid molecules is successfully achieved.

[0046] like Figure 5 The figure shows the electrocatalytic oxygen evolution data of the samples prepared in Example 1 and Comparative Example 1. According to the linear sweep voltammetry (LSV) curves, it can be seen that the present invention achieves an oxygen evolution rate of 10 mA cm⁻¹. -2 At that time, the overpotential of the L-ASP-NiFe-LDH sample was 223 mV, which was lower than that of NiFe-LDH (275 mV), showing excellent electrocatalytic oxygen evolution activity, which was better than that of the electrocatalytic oxygen evolution activity in Comparative Document 1.

[0047] Example 5 A method for preparing a chiral molecularly coupled layered hydroxide catalyst includes the following steps: (1) Preparation of precursor solution: 5 mmol nickel chloride hexahydrate, 2 mmol ferric chloride nonahydrate and 2 mmol L-aspartic acid solid powder were dissolved in 10 mL deionized water and stirred continuously at room temperature until the powder was completely dissolved and a uniform and stable dark brown liquid was formed in the beaker. The pH of the dark brown liquid was adjusted to 9 using sodium carbonate solution, and the mixture was brought to a final volume of 35 mL using deionized water. The mixture was then stirred at a constant speed for 5 min.

[0048] (2) Hydrothermal reaction: The mixed solution was transferred to the polytetrafluoroethylene liner of a 50 mL stainless steel high-pressure reactor and heated at 110 °C for 8 h to obtain chiral amino acid coupled nickel-iron hydroxide.

[0049] (3) Cleaning and drying: After the hydrothermal reaction is completed, the reaction product is taken out and washed three times by alternating centrifugation with deionized water and anhydrous ethanol. The centrifugation speed is 4000 r / min and the centrifugation time is 4 min.

[0050] After vacuum drying at 70℃ for 16 hours, the product is thoroughly ground to obtain a chiral molecularly coupled layered hydroxide catalyst (cm-NiFe-LDH, where cm represents a chiral molecule).

[0051] Example 6 A method for preparing a chiral molecularly coupled layered hydroxide catalyst includes the following steps: (1) Preparation of precursor solution: 5.5 mmol nickel chloride hexahydrate, 2.5 mmol ferric chloride nonahydrate and 2.5 mmol L-aspartic acid solid powder were dissolved in 12 mL deionized water and stirred continuously at room temperature until the powder was completely dissolved and a uniform and stable dark brown liquid was formed in the beaker. The pH of the dark brown liquid was adjusted to 8.8 using sodium carbonate solution, and the mixture was brought to a final volume of 40 mL using deionized water. The mixture was then stirred at a constant speed for 5 min.

[0052] (2) Hydrothermal reaction: The mixed solution was transferred to the polytetrafluoroethylene liner of a 50 mL stainless steel high-pressure reactor and heated at 120 °C for 15 h to obtain chiral amino acid coupled nickel iron hydroxide.

[0053] (3) Cleaning and drying: After the hydrothermal reaction is completed, the reaction product is taken out and washed three times by alternating centrifugation with deionized water and anhydrous ethanol. The centrifugation speed is 4000 r / min and the centrifugation time is 4 min.

[0054] After vacuum drying at 90℃ for 8 h, the product is thoroughly ground to obtain a chiral molecularly coupled layered hydroxide catalyst (cm-NiFe-LDH, where cm represents a chiral molecule).

[0055] Comparative Example 2 A method for preparing a chiral molecularly coupled layered hydroxide catalyst includes the following steps: (1) Preparation of precursor solution: 5 mmol nickel nitrate, 2 mmol ferric nitrate and 2 mmol L-aspartic acid solid powder were dissolved in 10 mL deionized water and stirred continuously at room temperature until the powder was completely dissolved and a uniform and stable dark brown liquid was formed in the beaker. The pH of the dark brown liquid was adjusted to 7.5 using sodium carbonate solution, and the mixture was brought to a final volume of 35 mL using deionized water. The mixture was then stirred at a constant speed for 5 min.

[0056] (2) Hydrothermal reaction: The mixed solution was transferred to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and heated at 115 °C for 12 h. The reaction was completed without the formation of chiral amino acid-coupled nickel-iron hydroxide.

[0057] In the method of this invention, the pH value is adjusted in the range of 8.5-9.0. When under strongly alkaline conditions (pH>10), metal ion precipitation and LDH structure destruction are easily caused, resulting in the failure of chiral molecule intercalation.

[0058] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing a chiral molecularly coupled layered hydroxide catalyst, characterized in that, Includes the following steps: (1) Preparation of precursor solution: Dissolve nickel source, iron source and chiral ligand solid powder in deionized water and stir to form initial solution; The pH of the initial solution was adjusted to 8.0–10.0 using an alkaline adjuster, and the mixture was stirred until homogeneous to form a mixed solution. (2) Hydrothermal reaction: The mixed solution is transferred to a reaction vessel, sealed and heated to obtain chiral molecularly coupled nickel-iron hydroxide; (3) Cleaning and drying: After the hydrothermal reaction is completed, the reaction product is taken out, cleaned, centrifuged, vacuum dried and ground to obtain the chiral molecularly coupled layered hydroxide catalyst.

2. The method for preparing a chiral molecularly coupled layered hydroxide catalyst according to claim 1, characterized in that, In step (1), the nickel source is selected from at least one of nickel chloride hexahydrate, nickel nitrate, nickel sulfate, or nickel acetate; and / or, the iron source is selected from at least one of ferric chloride nonahydrate, ferric chloride hexahydrate, ferric nitrate, or ferric sulfate; the chiral ligand is at least one of a chiral amino acid, a chiral amino acid derivative, a chiral diamine, or chiral lactic acid; and the total molar ratio of the nickel source, iron source, and chiral ligand is (5~7):(2~4):(2~4).

3. The method for preparing a chiral molecularly coupled layered hydroxide catalyst according to claim 2, characterized in that, The nickel source is nickel chloride hexahydrate, the iron source is ferric chloride nonahydrate, and the chiral ligands are L-aspartic acid, L-glutamic acid, L-threonine, and L-isoleucine, with the molar ratio of nickel chloride hexahydrate, ferric chloride nonahydrate, and chiral ligands being (5~6):(2~3):(2~3).

4. The method for preparing a chiral molecularly coupled layered hydroxide catalyst according to claim 1, characterized in that, In step (1), the alkalinity regulator is at least one aqueous solution of sodium carbonate, sodium bicarbonate, sodium hydroxide, or ammonia.

5. The method for preparing a chiral molecularly coupled layered hydroxide catalyst according to claim 1, characterized in that, After adjustment, the pH of the mixed solution was adjusted to 8.5–9.

0.

6. The method for preparing a chiral molecularly coupled layered hydroxide catalyst according to claim 1, characterized in that, In step (2), the reaction vessel is a stainless steel high-pressure reactor, and the mixed solution is transferred to the polytetrafluoroethylene lining of the stainless steel high-pressure reactor; the heating temperature is 110℃~120℃, and the heating time is 8~20 h.

7. The method for preparing a chiral molecularly coupled layered hydroxide catalyst according to claim 1, characterized in that, In step (3), the washing and centrifugation methods are as follows: wash three times by alternating centrifugation with deionized water and anhydrous ethanol, with a centrifugation speed of 4000~4500 r / min and a single centrifugation time of 3~5 min.

8. The method for preparing a chiral molecularly coupled layered hydroxide catalyst according to claim 1, characterized in that, In step (3), vacuum drying is performed at 70~90℃ for 8~16 h; grinding time is 30 min.

9. The chiral molecularly coupled layered hydroxide catalyst prepared by the method for preparing a chiral molecularly coupled layered hydroxide catalyst according to any one of claims 1-8.

10. The application of the chiral molecularly coupled layered hydroxide catalyst as described in claim 9 in the oxygen evolution reaction.

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