Macroscale Preparation and Application of Few-Layer Transition Metal Layered Double Hydroxides
By preparing a small layer transition metal layered double hydroxide, increasing the specific surface area and exposing the active site, the problem of poor conductivity in the prior art is solved, and efficient electrocatalytic water decomposition performance is achieved.
Patent Information
- Application Number
- CN202310177311.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-28
- Publication Date
- 2025-07-29
- Estimated Expiration
- 2043-02-28
AI Technical Summary
The existing transition metal layered double hydroxide has poor electrical conductivity and the active sites cannot be fully exposed, which limits its catalytic activity in electrocatalytic water decomposition.
By preparing a small layer of transition metal layered double hydroxide, increasing the specific surface area and exposing more defects and coordination unsaturated sites, a mixed solution of transition metal salt, surfactant and sodium borohydride was used to react, centrifuge, washing, and drying, and obtain an ultra-thin nanosheet structure with nanoflower morphology.
The catalytic activity and stability of the catalyst are improved, and excellent water oxidation reaction performance is shown, with low overpotential and good cycle stability.
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Figure CN116180127B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of the preparation of anodic electrode materials for electrolyzed water, and particularly relates to a method for the large-scale preparation of few-layer transition metal layered double hydroxides, the product prepared thereby, and the application thereof, especially the application as a water oxidation electrocatalyst in the electrocatalytic decomposition of water. Background Art
[0002] Hydrogen is not only an important industrial raw material but also a highly efficient secondary clean energy source, which is of great significance for the world to develop a low-carbon economy and alleviate the energy crisis. Electrocatalytic water splitting is one of the most promising low-carbon technologies for producing high-purity hydrogen, which can realize the efficient utilization of renewable energy sources such as hydropower, photovoltaic power generation, and wind power. Electrocatalytic water splitting includes two half-reactions, the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, and its efficiency is largely limited by the OER because this is a four-electron transfer process with slow kinetics. So far, the most successful commercial catalysts for OER are noble metal oxides such as IrO2 and RuO2, but the low reserves of noble metals limit their large-scale application. Therefore, it is crucial to develop non-noble metal OER electrocatalysts with rich reserves.
[0003] Among various transition metal-based oxygen evolution reaction electrocatalysts, transition metal layered double hydroxides (LDHs) have received extensive attention due to their rich reserves, adjustable composition, and unique two-dimensional layered structure. However, due to their poor conductivity and the inability to fully expose active sites, the further improvement of their activity is restricted.
[0004] Based on the above reasons, this application is proposed. Summary of the Invention
[0005] Based on the above reasons and aiming at the problems or defects existing in the prior art, the purpose of the present invention is to provide a method for the large-scale preparation of few-layer transition metal layered double hydroxides, the product prepared thereby, and the application thereof, so as to solve or at least partially solve the above technical defects existing in the prior art. Reducing the thickness of LDHs in the present invention is beneficial to increasing the specific surface area of LDHs and exposing more defects and coordinatively unsaturated sites, which is an effective method to improve its catalytic activity.
[0006] In order to achieve the above first object of the present invention, the technical solution adopted by the present invention is as follows:
[0007] A method for the large-scale preparation of few-layer transition metal layered double hydroxides, the method specifically comprising the following steps:
[0008] (a) Dissolve a transition metal salt and a surfactant in an inorganic solvent in sequence to prepare a solution A;
[0009] (b) Add sodium borohydride to solution A, and then react the resulting mixture at 25 - 50 °C with stirring for 10 - 30 min. After the reaction, centrifuge the product, wash it, and dry it to obtain the few-layer transition metal layered double hydroxide; wherein:
[0010] The surfactant includes any one or several of cetyltrimethylammonium bromide, sodium dodecylsulfonate, sodium dodecyl sulfate, etc.
[0011] Further, in the above technical solution, the transition metal salt is a transition metal nitrate.
[0012] Further, in the above technical solution, the transition metal in the transition metal salt includes any one or several of Ni, Fe, Co, Mn, Cr, etc.
[0013] Further, in the above technical solution, the transition metal layered double hydroxide is any one of NiFe-LDH, NiCo-LDH, NiMn-LDH, NiCr-LDH, CoFe-LDH, CoMn-LDH, NiCoMn-LDH, NiFeMn-LDH, etc.
[0014] Further, in the above technical solution, the inorganic solvent is preferably deionized water.
[0015] Further, in the above technical solution, the concentration of the transition metal salt in solution A is controlled at 0.01 - 3 mol / L.
[0016] Further, in the above technical solution, the concentration of the surfactant in solution A is controlled at 0.01 - 0.1 mol / L.
[0017] Further, in the above technical solution, the molar ratio of the transition metal salt to sodium borohydride is controlled at 1:2 - 3.
[0018] Further, in the above technical solution, the process conditions for centrifugation and washing are: centrifuge the product at a speed of 5000 - 10000 r / min for 2 - 5 min, then pour off the supernatant, and wash it with deionized water 5 - 10 times.
[0019] Further, in the above technical solution, the process conditions for drying are: dry in an oven at 50 - 100 °C for 6 - 12 h.
[0020] The second object of the present invention is to provide the few-layer transition metal layered double hydroxide prepared by the above method.
[0021] The third object of the present invention is to provide the application of the few-layer transition metal layered double hydroxide prepared by the above method as a water oxidation electrocatalyst in the electrocatalytic decomposition of water.
[0022] A water oxidation electrocatalyst, which comprises few-layer transition metal layered double hydroxides prepared by the above-mentioned method.
[0023] The remarkable advantages and beneficial effects of the present invention are as follows:
[0024] 1. The preparation method of the present invention is simple and easy to operate, has a short preparation time, mild reaction conditions and a high yield.
[0025] 2. The few-layer transition metal layered double hydroxides prepared by the present invention have a large specific surface area, can expose more active sites, and at the same time their few-layer structure is conducive to the formation of more defects and coordination unsaturated sites, which is beneficial to improving the intrinsic activity of the catalyst.
[0026] 3. The few-layer transition metal layered double hydroxides prepared by the present invention have a low overpotential for water oxidation reaction and excellent cycle stability and durability performance. Description of the Drawings
[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0028] Figure 1 It is the X-ray diffraction pattern of f-NiFe-LDH prepared in Example 1 of the present invention.
[0029] Figure 2 It is the scanning electron microscope image (SEM) of f-NiFe-LDH prepared in Example 1 of the present invention at different magnification multiples.
[0030] Figure 3 It is the atomic force microscope image (AFM) of f-NiFe-LDH prepared in Example 1 of the present invention.
[0031] Figure 4 It is the linear sweep voltammetry curve obtained by the water oxidation performance test of f-NiFe-LDH prepared in Example 1 of the present invention and commercial RuO2 in 1M KOH electrolyte.
[0032] Figure 5 It is the LSV curve of f-NiFe-LDH prepared in Example 1 of the present invention before and after 3000 cyclic voltammetry tests in 1M KOH electrolyte.
[0033] Figure 6It is the chronoamperometry curve of the f-NiFe-LDH prepared in Example 1 of the present invention at a fixed potential in 1M KOH electrolyte.
[0034] Figure 7 It is the linear sweep voltammetry curve obtained by using the f-CoFe-LDH prepared in Example 2 of the present invention and commercial RuO2 for water oxidation performance test in 1M KOH electrolyte.
[0035] Figure 8 It is the linear sweep voltammetry curve obtained by using the f-NiFeMn-LDH prepared in Example 3 of the present invention and commercial RuO2 for water oxidation performance test in 1M KOH electrolyte. Detailed implementation mode
[0036] The present invention provides a method for the macroscale preparation of few-layer transition metal layered double hydroxides. The preparation method of the present invention is simple and easy to implement, has a short preparation time, mild reaction conditions, a high yield, and uses the few-layer transition metal layered double hydroxides prepared by the present invention as a water oxidation electrocatalyst for electrocatalytic water splitting, showing excellent catalytic activity and stability.
[0037] The present invention will be further described in detail below through implementation cases.
[0038] For a better understanding of the present invention rather than limiting the scope of the present invention, all numbers representing amounts, percentages, and other numerical values used in this application should be understood to be modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification are approximate values, which may vary according to the different desired properties. Each numerical parameter should be regarded as being obtained at least according to the reported significant figures and by the conventional rounding method.
[0039] The equipment and raw materials used in the present invention can be purchased from the market or are commonly used in the art. The methods in the following implementation examples are conventional methods in the art unless otherwise specified.
[0040] Example 1
[0041] In this example, nickel nitrate hexahydrate and iron nitrate nonahydrate are used as transition metal salts to further illustrate the method for the macroscale preparation of few-layer transition metal layered double hydroxides in this application.
[0042] A method for the macroscale preparation of few-layer transition metal layered double hydroxides in this example includes the following steps:
[0043] (a) At room temperature, 1.8581 g of nickel nitrate hexahydrate (6.39 mmol), 0.8605 g (2.13 mmol) of iron nitrate nonahydrate and 0.5 g (1.37 mmol) of cetyltrimethylammonium bromide were successively dissolved in 50 mL of deionized water to prepare solution A.
[0044] (b) At room temperature (25 °C), 0.9684 g of sodium borohydride (25.6 mmol) was added to solution A, and stirring was continued for 20 min. Subsequently, the above mixture was centrifuged at a speed of 10000 r / min for 3 min, and then the supernatant was poured off and washed 5 times with deionized water. The washed product was dried in an oven at 60 °C for 6 h to obtain few-layer NiFe layered double hydroxide (f-NiFe-LDH).
[0045] Example 2
[0046] In this example, cobalt nitrate hexahydrate and iron nitrate nonahydrate were used as transition metal salts to further illustrate the method for the large-scale preparation of few-layer transition metal layered double hydroxides of the present application.
[0047] A method for the large-scale preparation of few-layer transition metal layered double hydroxides in this example includes the following steps:
[0048] (a) At room temperature, 1.8597 g of cobalt nitrate hexahydrate (6.39 mmol), 0.8605 g (2.13 mmol) of iron nitrate nonahydrate and 0.5 g of cetyltrimethylammonium bromide (1.37 mmol) were successively dissolved in 50 mL of deionized water to prepare solution A.
[0049] (b) At room temperature, 0.9684 g of sodium borohydride (25.6 mmol) was added to solution A, and stirring was continued for 20 min. Subsequently, the above mixture was centrifuged at a speed of 10000 r / min for 3 min, and then the supernatant was poured off and washed 5 times with deionized water. The washed product was dried in an oven at 60 °C for 6 h to obtain few-layer CoFe layered double hydroxide (f-CoFe-LDH).
[0050] Example 3
[0051] In this example, nickel nitrate hexahydrate, iron nitrate nonahydrate and manganese nitrate tetrahydrate were used as transition metal salts to further illustrate the method for the large-scale preparation of few-layer transition metal layered double hydroxides of the present application.
[0052] A method for the large-scale preparation of few-layer transition metal layered double hydroxides in this example includes the following steps:
[0053] (a) At room temperature, 1.4859 g of nickel nitrate hexahydrate (5.11 mmol), 0.6868 g (1.70 mmol) of iron nitrate nonahydrate, 0.4267 g (1.70 mmol) of manganese nitrate tetrahydrate, and 0.5 g (1.37 mmol) of cetyltrimethylammonium bromide were successively dissolved in 50 mL of deionized water to prepare solution A.
[0054] (b) At room temperature, 0.9684 g of sodium borohydride (25.6 mmol) was added to solution A, and stirring was continued for 20 min. Subsequently, the above mixture was centrifuged at a speed of 10,000 r / min for 3 min, and then the supernatant was poured off and washed 5 times with deionized water. The washed product was placed in an oven at 60 °C and dried for 6 h to obtain few-layer NiFeMn layered double hydroxide (f-NiFeMn-LDH).
[0055] Electrochemical performance test:
[0056] The water oxidation activities of the products prepared in the above examples and the RuO2 catalyst in the prior art were tested using a Gamry electrochemical workstation.
[0057] In the above electrochemical performance tests, the Hg / HgO electrode was used as the reference electrode, the carbon rod was used as the counter electrode, the glassy carbon electrode loaded with the catalyst was used as the working electrode, the electrolyte was 1 M KOH, and oxygen was introduced for 30 min before the water oxidation performance test to saturate the electrolyte with oxygen. Oxygen was introduced throughout the test to maintain the equilibrium potential of the oxygen evolution reaction unchanged. The scan rate of the linear sweep voltammetry test was 5 mV / s.
[0058] Figure 1 is the X-ray diffraction pattern of the f-NiFe-LDH prepared in Example 1 of the present invention. The results show that f-NiFe-LDH exhibits a typical layered double hydroxide structure.
[0059] Figure 2 is the scanning electron microscope image (SEM) of the f-NiFe-LDH prepared in Example 1 of the present invention at different magnifications. From Figure 2 it can be seen that the prepared f-NiFe-LDH exhibits a nanoflower morphology, and the nanoflowers are composed of curled ultrathin nanosheets.
[0060] Figure 3 is the atomic force microscope image (AFM) of the f-NiFe-LDH prepared in Example 1 of the present invention. It can be seen that the thickness of the nanosheets of f-NiFe-LDH is about 1.1 nm and is composed of 1-2 layers of single-layer hydrotalcite, confirming its few-layer structure.
[0061] Figure 4The linear sweep voltammetry curves obtained from the water oxidation performance tests of the f-NiFe-LDH prepared in Example 1 of the present invention and commercial RuO2 in a 1M KOH electrolyte. It can be seen that at a current density of 10 mA cm -2 when the overpotential of f-NiFe-LDH is only 209 mV, far lower than 284 mV of commercial RuO2, indicating its excellent water oxidation activity.
[0062] Figure 5 The LSV curves of the f-NiFe-LDH prepared in Example 1 of the present invention before and after 3000 cyclic voltammetry tests in a 1M KOH electrolyte. It can be seen that the LSV curve after 3000 cyclic voltammetry tests basically coincides with that before the test, confirming the excellent cyclic stability of f-NiFe-LDH.
[0063] Figure 6 The chronoamperometry curve of the f-NiFe-LDH prepared in Example 1 of the present invention at a fixed potential in a 1M KOH electrolyte. It can be seen that at an overpotential of 210 mV, the current density of f-NiFe-LDH can remain basically unchanged for 60 h, indicating its excellent stability.
[0064] Figure 7 The linear sweep voltammetry curves obtained from the water oxidation performance tests of the f-CoFe-LDH prepared in Example 2 of the present invention and commercial RuO2 in a 1M KOH electrolyte. It can be seen that at a current density of 10 mA cm -2 when the overpotential of f-CoFe-LDH is 279 mV, lower than 284 mV of commercial RuO2, indicating its excellent water oxidation activity.
[0065] Figure 8 The linear sweep voltammetry curves obtained from the water oxidation performance tests of the f-NiFeMn-LDH prepared in Example 3 of the present invention and commercial RuO2 in a 1M KOH electrolyte. It can be seen that at a current density of 10 mA cm -2 when the overpotential of f-NiFeMn-LDH is 227 mV, lower than 284 mV of commercial RuO2, indicating its excellent water oxidation activity.
[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for the large-scale preparation of few-layer transition metal layered double hydroxides, characterized in that: The method specifically includes the following steps: (a) Dissolve a transition metal salt and a surfactant in an inorganic solvent in sequence to prepare solution A; (b) Add sodium borohydride to solution A, and then react the resulting mixture at 25 - 50 °C under stirring conditions for 10 - 30 min. After the reaction ends, centrifuge, wash, and dry the product to obtain the few-layer transition metal layered double hydroxide; wherein: The surfactant includes any one or several of cetyltrimethylammonium bromide, sodium dodecyl sulfonate, and sodium dodecyl sulfate; The transition metal in the transition metal salt includes any one or several of Ni, Fe, Co, Mn, and Cr; The few-layer transition metal layered double hydroxide is any one of NiFe-LDH, NiCo-LDH, NiMn-LDH, NiCr-LDH, CoFe-LDH, CoMn-LDH, NiCoMn-LDH, and NiFeMn-LDH; The concentration of the transition metal salt in solution A is controlled at 0.01 - 3 mol / L; The concentration of the surfactant in solution A is controlled at 0.01 - 0.1 mol / L; The molar ratio of the transition metal salt to sodium borohydride is controlled at 1:2 - 3.
2. The few-layer transition metal layered double hydroxide prepared by the method according to claim 1.
3. Application of the few-layer transition metal layered double hydroxide prepared by the method according to claim 1 as a water oxidation electrocatalyst in the electrocatalytic decomposition of water.
4. A water oxidation electrocatalyst, characterized in that: The catalyst includes the few-layer transition metal layered double hydroxide prepared by the method according to claim 1.