Graphene hollow sphere loaded nickel-manganese layered double hydroxide and preparation method and application thereof
Patent Information
- Application Number
- CN202311349215.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-17
- Publication Date
- 2026-08-21
- Estimated Expiration
- 2043-10-17
AI Technical Summary
这些方法不仅反应条件比较苛刻、重复率较差、产率低，而且有些工艺比较复杂、成本高
[0060] (1) The preparation method involved in this invention is simple, mild, highly reproducible, low in production cost, does not use toxic or harmful reagents, and is environmentally friendly.
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Figure CN117568853B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of nanomaterials and electrocatalysis, specifically to a graphene hollow sphere-supported nickel-manganese layered double hydroxide, its preparation method, and its application. Background Technology
[0002] The overexploitation of fossil fuels has led to intractable problems such as ecosystem destruction, a global energy crisis, climate change, and the greenhouse effect. Therefore, developing and utilizing an environmentally friendly and renewable energy source to replace traditional fossil fuels is crucial for the sustainable development of the economy and society. Undoubtedly, hydrogen energy is an environmentally friendly, green, and sustainable energy source, and water electrolysis for hydrogen production is one of the most promising commercial technologies. To date, Pt, Ir, and Ru noble metal materials are generally considered the most active catalysts for water electrolysis for hydrogen production. However, the high cost and limited natural reserves of these noble metal materials severely restrict their large-scale commercial application. To date, various transition metal-based composite catalysts, including oxides, hydroxides, selenides, carbides, phosphates, and sulfides, have been widely used in water electrolysis for hydrogen production. Among them, bimetallic hydroxides / oxides have attracted attention as promising catalysts due to their low cost, high abundance, and synergistic effects, resulting in better electrochemical activity than single-metal hydroxides / oxides.
[0003] Layered bimetallic hydroxides (LDHs) are typical two-dimensional anionic layered materials, consisting of positively charged metal hydroxide layers and interlayer spaces containing charge-compensating anions. The unique structural characteristics of LDHs, such as their two-dimensional ordered and uniformly dispersed layered lattice elements, facilitate highly uniform dispersion and exposure of the active components, thereby significantly improving their catalytic performance. However, the poor conductivity and limited exposure of active sites due to their stacking structure result in unsatisfactory electrocatalytic activity in LDHs.
[0004] Carbon-based materials, such as commonly used carbon nanofibers, carbon nanotubes (CNTs), and graphene, are considered to possess excellent electrocatalytic activity due to their large specific surface area, good mechanical stability, and high electrical conductivity. Compared with ordinary carbon-based materials, hollow graphene spheres have a three-dimensional porous structure, a large specific surface area, and numerous active sites, making them the preferred carbon-based material. By combining graphene with LDH, the electrical conductivity and stability of LDH can be significantly improved, thereby enhancing its electrocatalytic activity. However, currently reported methods for preparing LDH / graphene composite materials include hydrothermal methods, layer-by-layer assembly methods, and electrodeposition methods. These methods not only have harsh reaction conditions, poor reproducibility, and low yields, but some processes are also complex and costly. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing graphene hollow spheres supported on nickel-manganese layered double hydroxides (NiMn-LDH). This method utilizes the three-dimensional porous structure of graphene hollow spheres to co-precipitate NiMn-LDH nanosheets on their surface, generating a graphene hollow sphere-supported NiMn-LDH composite material with a hollow core-shell structure. This hollow core-shell structure provides more electroactive catalytic sites, higher conductivity, and faster ion-electron transport rates, which is beneficial for improving catalytic performance. This invention has advantages such as simple preparation process, mild conditions, high reproducibility, low production cost, no use of toxic or harmful reagents, and environmental friendliness. Furthermore, electrochemical experiments have demonstrated that the obtained material exhibits high efficiency in the electrocatalytic decomposition of water and hydrogen evolution in an alkaline electrolyte system.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] The first aspect of this invention is to provide a method for preparing a graphene hollow sphere-supported nickel-manganese layered double hydroxide, comprising the following steps:
[0008] (1) Polystyrene (PS) and graphene oxide (GO) were dispersed in a solvent and mixed to obtain a PS-GO mixed solution. The mixture was stirred to obtain the reaction product.
[0009] (2) Heating the reaction product yields graphene hollow spheres (SG);
[0010] (3) Disperse the SG in an alcohol solvent, and add nickel salt and manganese salt to obtain a mixed solution, and heat it for later use;
[0011] (4) Add hexamethylenetetramine (HMT) to the mixed solution and react to obtain graphene hollow spheres loaded with nickel-manganese layered double hydroxide.
[0012] In a preferred embodiment, the solutions of PS and GO can be either dispersed separately in a solvent and then mixed, or PS and GO can be dispersed in the same solvent sequentially and then mixed.
[0013] The solvent may be one or more of the following: water, DMF, aromatic hydrocarbons (such as benzene, toluene, chlorobenzene), aliphatic hydrocarbons (such as dichloromethane, chloroform), carboxylic acids, esters, alcohols, ethers, phenols, aldehydes, and ketones.
[0014] In a more preferred embodiment, the water is preferably deionized water.
[0015] In a preferred embodiment, after dispersing the PS in a solvent, the PS solution is further stirred.
[0016] In a preferred embodiment, the stirring time is preferably 2 to 12 hours, more preferably 4 to 10 hours, and even more preferably 5 to 8 hours.
[0017] In a preferred embodiment, the stirring temperature is preferably 20-40°C, more preferably 20-30°C, such as 23°C, 26°C, 29°C, etc.
[0018] In a preferred embodiment, the preparation of the GO solution involves dispersing the GO in a solvent and then stirring.
[0019] In a preferred embodiment, the stirring time is preferably 12-48 hours, more preferably 20-40 hours, and even more preferably 24-36 hours.
[0020] In a preferred embodiment, the stirring temperature is preferably 20-40°C, more preferably 20-30°C, such as 23°C, 26°C, 29°C, etc.
[0021] In a preferred embodiment, the weight-average molecular weight of PS is preferably 3,000-100,000, preferably 5,000-80,000, more preferably 8,000-50,000, and even more preferably 10,000-40,000, such as 7,000.
[0022] In a preferred embodiment, the mass-to-volume ratio of polystyrene, graphene oxide, and solvent is preferably (0.01–0.3 g):(0.1–0.6 g):(20–60 mL), more preferably (0.03–0.2 g):(0.1–0.5 g):(30–50 mL), and even more preferably (0.05–0.1 g):(0.1–0.4 g):(30–40 mL).
[0023] In a preferred embodiment, the PS solution and the GO solution are mixed, preferably by dropwise addition, more preferably by slow dropwise addition through a constant pressure dropping funnel.
[0024] In a preferred embodiment, the PS-GO mixed solution is subjected to a stirring reaction, and the stirring time is preferably 5 to 24 hours, more preferably 8 to 20 hours, and even more preferably 10 to 15 hours.
[0025] In a preferred embodiment, the stirring temperature of the PS-GO mixed solution is preferably 20-40°C, more preferably 20-30°C.
[0026] In a preferred embodiment, the stirring of the PS-GO mixture is preferably one or more of magnetic stirring, mechanical stirring, etc.
[0027] In a preferred embodiment, after the stirring reaction is completed, the resulting reaction product needs to be freeze-dried.
[0028] In a preferred embodiment, the freeze-drying method is preferably one or more of vacuum freeze-drying and freeze spray drying.
[0029] In a preferred embodiment, the freeze-drying temperature is preferably -100 to -50°C, more preferably -90 to -50°C, and even more preferably -80 to -50°C.
[0030] In a preferred embodiment, the freeze-drying time is preferably 12-48 hours, more preferably 20-36 hours, and even more preferably 20-28 hours.
[0031] In a preferred embodiment, the vacuum degree of the freeze-drying is preferably 1-10 Pa, more preferably 2-6 Pa.
[0032] In a preferred embodiment, the heating reaction in step (2) is preferably a calcination reaction.
[0033] In a preferred embodiment, the calcination reaction temperature is preferably 200–1000°C, more preferably 300–600°C, and even more preferably 400–500°C.
[0034] In a preferred embodiment, the calcination reaction time is preferably 0.5 to 8 hours, more preferably 1 to 6 hours, and even more preferably 2 to 5 hours.
[0035] In a preferred embodiment, the calcination reaction can be carried out in one or more of a muffle furnace, a tube furnace, a resistance furnace, a microwave oven, and a high-temperature furnace.
[0036] In a preferred embodiment, the calcination reaction is carried out under an inert atmosphere, preferably one or more of nitrogen, argon, and oxygen. More preferably, the flow rate of the inert atmosphere is 20–200 sccm, and even more preferably 50–150 sccm.
[0037] In a preferred embodiment, the alcohol solvent in step (3) is preferably one or more of methanol, ethanol, n-propanol, and isopropanol.
[0038] In a preferred embodiment, the content of the alcohol solution is preferably 20-95%, more preferably 40-75%, and even more preferably 50-60%.
[0039] In a preferred embodiment, the nickel salt is preferably soluble in the alcohol solution and provides Ni 2+ It is one or more of inorganic nickel salts and organic nickel salts, more preferably a soluble nickel salt of inorganic or organic nickel salts; more preferably one or more of nickel chloride, nickel nitrate, nickel acetate, nickel sulfate, and nickel sulfite.
[0040] In a preferred embodiment, the manganese salt is preferably soluble in the alcohol solution and provides Mn. 2+ It is one or more of inorganic manganese salts and organic manganese salts, more preferably soluble manganese salts of inorganic or organic manganese salts; more preferably one or more of manganese chloride, manganese nitrate, manganese acetate, and manganese sulfate.
[0041] In a preferred embodiment, the mass-to-volume ratio of SG, nickel salt, manganese salt, and alcohol solution is preferably (0.01–0.2 g):(0.1–1 g):(0.01–0.5 g):(10–100 mL), more preferably (0.01–0.1 g):(0.2–1 g):(0.02–0.4 g):(20–80 mL), and even more preferably (0.01–0.08 g):(0.2–0.8 g):(0.05–0.2 g):(40–60 mL).
[0042] In a more preferred embodiment, the alcohol solution, nickel salt, and manganese salt of SG need to be thoroughly stirred during mixing to ensure uniform mixing; wherein the stirring time is preferably 10 to 90 minutes, more preferably 10 to 60 minutes.
[0043] In a preferred embodiment, the heating temperature of the mixed solution in step (3) is preferably 40-200°C, more preferably 60-150°C, and even more preferably 60-100°C, such as 60°C, 70°C, 80°C, 90°C, etc.
[0044] In a preferred embodiment, the hexamethylenetetramine (HMT) is dispersed in an alcohol solution, which is preferably one or more of methanol, ethanol, n-propanol, and isopropanol; more preferably, the content of the alcohol solution is 20-95%, and even more preferably 40-75%.
[0045] In a preferred embodiment, the amount of HMT used per 1g SG is 1 to 100g, more preferably 8 to 80g, and even more preferably 10 to 80g.
[0046] In a preferred embodiment, the HMT solution is added to the mixed solution, preferably by dripping, and more preferably by slowly dripping through a constant pressure dropping funnel.
[0047] In a preferred embodiment, the reaction time in step (4) is preferably 1 to 12 hours, more preferably 2 to 10 hours, and even more preferably 4 to 8 hours.
[0048] In a preferred embodiment, the reaction temperature in step (4) is preferably 60-150°C, more preferably 60-100°C, such as 60°C, 70°C, 80°C, 90°C, etc.
[0049] In a preferred embodiment, after the reaction in step (4) is completed, the product obtained from the reaction needs to be washed, centrifuged, and freeze-dried.
[0050] In a preferred embodiment, the washing is preferably performed by alternating washing with ethanol and distilled water multiple times.
[0051] In a preferred embodiment, the freeze-drying method is preferably one or more of vacuum freeze-drying and freeze spray drying.
[0052] In a preferred embodiment, the freeze-drying temperature is preferably -100 to -50°C, more preferably -90 to -50°C, and even more preferably -80 to -50°C.
[0053] In a preferred embodiment, the freeze-drying time is preferably 12-48 hours, more preferably 20-36 hours, and even more preferably 20-28 hours.
[0054] In a preferred embodiment, the vacuum degree of the freeze-drying is preferably 1-10 Pa, more preferably 2-6 Pa, such as 4 Pa, 5 Pa, 6 Pa, etc.
[0055] A second aspect of the present invention is to provide a material of graphene hollow spheres loaded with nickel-manganese layered double hydroxides, wherein the graphene hollow spheres loaded with nickel-manganese layered double hydroxides are obtained by the preparation method of graphene hollow spheres loaded with nickel-manganese layered double hydroxides as described in the first aspect.
[0056] In a preferred embodiment, the graphene hollow sphere loaded with nickel-manganese layered double hydroxide comprises graphene hollow spheres and nickel-manganese layered double hydroxide nanosheets loaded thereon.
[0057] More preferably, the diameter of the graphene hollow spheres is 200-1200 nm, more preferably 400-1000 nm, more preferably 500-800 nm, and even more preferably 600-700 nm.
[0058] A third aspect of the present invention is to provide an application of the graphene hollow sphere-supported nickel-manganese layered double hydroxide, wherein the graphene hollow sphere-supported nickel-manganese layered double hydroxide is used as a catalyst for hydrogen production by water electrolysis.
[0059] Compared with the prior art, the method of the present invention has the following beneficial effects:
[0060] (1) The preparation method involved in this invention is simple, mild, highly reproducible, low in production cost, does not use toxic or harmful reagents, and is environmentally friendly.
[0061] (2) The graphene hollow sphere-supported nickel-manganese layered double hydroxide prepared in this invention has a hollow core-shell structure, which can provide more electroactive catalytic sites, higher conductivity and faster ion-electron transport rate, which is beneficial to the improvement of catalytic performance.
[0062] (3) The graphene hollow sphere-supported nickel-manganese layered double hydroxide prepared by the present invention has a high efficiency of hydrogen evolution by water electrolysis in an alkaline electrolyte system and excellent catalytic performance. Attached Figure Description
[0063] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the graphene hollow spheres loaded with nickel-manganese layered double hydroxide obtained in the present invention.
[0064] Figure 2(a) is a transmission electron microscope (TEM) image of the graphene hollow spheres obtained in the present invention.
[0065] Figure 2(b) is a transmission electron microscope (TEM) image of graphene hollow spheres loaded with nickel-manganese layered double hydroxide obtained in the present invention.
[0066] Figure 3(a) is a low-magnification scanning electron microscope (SEM) image of the graphene hollow spheres loaded with nickel-manganese layered double hydroxide obtained in the present invention.
[0067] Figure 3(b) is a high-magnification scanning electron microscope (SEM) image of the graphene hollow spheres loaded with nickel-manganese layered double hydroxide obtained in the present invention.
[0068] Figure 4 The graph shows the hydrogen evolution performance of the graphene hollow spheres supported on nickel-manganese layered double hydroxides obtained in this invention in an alkaline water system. Detailed Implementation
[0069] The following describes the embodiments of the present invention through specific examples and in conjunction with the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific examples, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0070] This invention discloses a method for preparing graphene hollow spheres loaded with nickel-manganese layered double hydroxides, comprising the following steps:
[0071] (1) Polystyrene (PS) and graphene oxide (GO) were dispersed in a solvent and mixed to obtain a PS-GO mixed solution. The mixture was stirred to obtain the reaction product.
[0072] (2) Heating the reaction product yields graphene hollow spheres (SG);
[0073] (3) Disperse the SG in an alcohol solvent, and add nickel salt and manganese salt to obtain a mixed solution, and heat it for later use;
[0074] (4) Add hexamethylenetetramine (HMT) to the mixed solution and react to obtain graphene hollow spheres loaded with nickel-manganese layered double hydroxide.
[0075] The technical solution of this application will be further illustrated by the following embodiments:
[0076] Example 1
[0077] a. Weigh 99 mg of polystyrene (PS), disperse it in 33 mL of deionized water, and stir at room temperature for 6 h to obtain a PS aqueous solution;
[0078] b. Weigh 0.3g of graphene oxide (GO) and disperse it in 30mL of deionized water, and stir at room temperature for 24 hours to obtain a GO aqueous solution;
[0079] c. The PS aqueous solution obtained in step a is added dropwise to the GO aqueous solution obtained in step b through a constant pressure dropping funnel. The mixture is then stirred on a magnetic stirrer for 12 hours to allow for a complete reaction. The resulting product is then placed in a vacuum freeze dryer and freeze-dried for 24 hours at a freezing temperature of -60°C and a vacuum degree of 5 Pa.
[0080] d. Place the freeze-dried product from step c in a tube furnace and heat it to 500°C under N2 or Ar atmosphere with a gas flow rate of 100 sccm for 2 hours to obtain graphene hollow spheres (SG).
[0081] e. Weigh 20 mg of SG obtained in step d and disperse it in 60 mL of 75% ethanol aqueous solution. Then add 713 mg of nickel chloride and 126 mg of manganese chloride, stir for 30 min to mix thoroughly, and then heat the mixed solution to 80 °C for later use.
[0082] f. Weigh 700 mg of hexamethylenetetramine (HMT) and disperse it in 10 mL of 75% ethanol aqueous solution. Stir for 30 min to obtain HMT solution;
[0083] g. Add HMT solution dropwise to the solution obtained in step e through a constant pressure dropping funnel and react for 6 hours.
[0084] h. Wash the product obtained in step g with ethanol and distilled water alternately several times, and then centrifuge it using a high-speed centrifuge. Place the product obtained by centrifugation in a vacuum freeze dryer and freeze-dry it for 24 hours at a freezing temperature of -60℃ and a vacuum degree of 5Pa. The black solid material obtained after drying is graphene hollow sphere-supported nickel-manganese layered double hydroxide.
[0085] Example 2
[0086] c. Weigh 80 mg of polystyrene (PS), disperse it in 30 mL of deionized water, and stir at room temperature for 5.5 h to obtain a PS aqueous solution;
[0087] d. Weigh 0.25 g of graphene oxide (GO) and disperse it in 30 mL of deionized water, and stir at room temperature for 24 hours to obtain a GO aqueous solution;
[0088] c. The PS aqueous solution obtained in step a is added dropwise to the GO aqueous solution obtained in step b through a constant pressure dropping funnel. The mixture is then stirred on a magnetic stirrer for 12 hours to allow for a complete reaction. The resulting product is then placed in a vacuum freeze dryer and freeze-dried for 24 hours at a freezing temperature of -70°C and a vacuum degree of 5 Pa.
[0089] d. Place the freeze-dried product from step c in a tube furnace and heat it to 450°C under N2 or Ar atmosphere with a gas flow rate of 100 sccm for 3 hours to obtain graphene hollow spheres (SG).
[0090] e. Weigh 15 mg of the SG obtained in step d and disperse it in 60 mL of 75% ethanol aqueous solution. Then add 700 mg of nickel chloride and 115 mg of manganese chloride, stir for 30 min to mix thoroughly, and then heat the mixed solution to 90 °C for later use.
[0091] f. Weigh 650 mg of hexamethylenetetramine (HMT) and disperse it in 20 mL of 75% ethanol aqueous solution. Stir for 30 min to obtain HMT solution;
[0092] g. Add HMT solution dropwise to the solution obtained in step e through a constant pressure dropping funnel and react for 7 hours.
[0093] h. The product obtained in step g was washed repeatedly with alternating ethanol and distilled water, and then centrifuged using a high-speed centrifuge. The product obtained by centrifugation was placed in a vacuum freeze dryer and freeze-dried for 24 hours at a freezing temperature of -70℃ and a vacuum degree of 5Pa. The black solid material obtained after drying is graphene hollow sphere-supported nickel-manganese layered double hydroxide.
[0094] Example 3
[0095] e. Weigh 70 mg of polystyrene (PS), disperse it in 30 mL of deionized water, and stir at room temperature for 5.5 h to obtain a PS aqueous solution;
[0096] f. Weigh 0.22 g of graphene oxide (GO) and disperse it in 30 mL of deionized water, and stir at room temperature for 24 hours to obtain a GO aqueous solution;
[0097] c. The PS aqueous solution obtained in step a is added dropwise to the GO aqueous solution obtained in step b through a constant pressure dropping funnel. The mixture is then stirred on a magnetic stirrer for 12 hours to allow for a complete reaction. The resulting product is then placed in a vacuum freeze dryer and freeze-dried for 24 hours at a freezing temperature of -60°C and a vacuum degree of 5 Pa.
[0098] d. Place the freeze-dried product from step c in a tube furnace and heat it to 450°C under a N2 or Ar atmosphere with a gas flow rate of 100 sccm for 3.5 hours to obtain graphene hollow spheres (SG).
[0099] e. Weigh 20 mg of the SG obtained in step d and disperse it in 60 mL of 75% ethanol aqueous solution. Then add 700 mg of nickel chloride and 120 mg of manganese chloride, stir for 30 min to mix it thoroughly, and then heat the mixed solution to 80 °C for later use.
[0100] f. Weigh 650 mg of hexamethylenetetramine (HMT) and disperse it in 20 mL of 75% ethanol aqueous solution. Stir for 30 min to obtain HMT solution;
[0101] g. Add HMT solution dropwise to the solution obtained in step e through a constant pressure dropping funnel and react for 7 hours.
[0102] h. The product obtained in step g was washed repeatedly with alternating ethanol and distilled water, and then centrifuged using a high-speed centrifuge. The product obtained by centrifugation was placed in a vacuum freeze dryer and freeze-dried for 24 hours at a freezing temperature of -70℃ and a vacuum degree of 5Pa. The black solid material obtained after drying is graphene hollow sphere-supported nickel-manganese layered double hydroxide.
[0103] To verify the successful synthesis of the graphene hollow sphere-supported nickel-manganese layered double hydroxide prepared by the aqueous coprecipitation method of this invention, its structure was characterized.
[0104] Figure 1 This is an X-ray diffraction (XRD) pattern of the graphene hollow spheres loaded with nickel-manganese layered double hydroxide obtained in this invention. In the figure, the horizontal axis represents the X-ray diffraction angle (degrees), and the vertical axis represents the X-ray diffraction intensity. The curves in the figure represent the X-ray diffraction intensity characteristics of the material. Figure 1 The (003), (006), (101), (012), (015), (018), (110), and (113) diffraction peaks appearing in the sample are characteristic diffraction peaks of NiMn-LDH. The XRD pattern of the product is in good agreement with the standard card (JCPDS NO.38-0715).
[0105] Figures 2(a) and 2(b) are transmission electron microscopy (TEM) images of the graphene hollow spheres and the graphene hollow spheres loaded with nickel-manganese layered double hydroxides obtained in the present invention. As can be seen from Figure 2, SG is a hollow structure with a diameter of 600-700 nm, and NiMn-LDH sheets are grown on the surface of SG.
[0106] Figures 3(a) and 3(b) are low-magnification and high-magnification scanning electron microscope (SEM) images of the graphene hollow spheres loaded with nickel-manganese layered double hydroxides obtained in the present invention. As can be seen from Figure 3, flower-like NiMn-LDH is uniformly covered on the SG surface.
[0107] Furthermore, the performance of the graphene hollow sphere-supported nickel-manganese layered double hydroxide for hydrogen production via water electrolysis prepared in this embodiment was also tested in this invention:
[0108] This invention utilizes a CHI660E electrochemical workstation to determine the hydrogen evolution performance (HER) of graphene hollow spheres supported on nickel-manganese layered double hydroxides in a nitrogen-filled 1.0 M KOH solution. The catalyst coated on nickel foam was used as the working electrode, Hg / HgO (1.0 M KOH) as the reference electrode, and platinum-carbon as the counter electrode to test the HER performance of the material. The HER was measured at 5 mV s. -1 The LSV curves tested at the scan rate are as follows: Figure 4 As shown. Test results indicate that the prepared graphene hollow sphere-supported nickel-manganese layered double hydroxide electrolysis water production hydrogen catalyst exhibits good performance at 10 mA / cm². -2 At current density, its overpotential is 181mV, which is much lower than that of general water electrolysis hydrogen evolution materials, making it an excellent water electrolysis hydrogen evolution catalyst.
[0109] In summary, the method for preparing graphene hollow spheres loaded with nickel-manganese layered double hydroxide (NiMn-LDH) disclosed in this invention utilizes the three-dimensional porous structure of graphene hollow spheres to co-precipitate NiMn-LDH nanosheets on their surface, generating a graphene hollow sphere-loaded NiMn-LDH composite material with a hollow core-shell structure. This invention features a simple preparation process, mild conditions, high reproducibility, low production cost, and does not use toxic or harmful reagents, making it environmentally friendly. Furthermore, electrochemical experiments have demonstrated that the obtained material exhibits high efficiency in the electrocatalytic decomposition of water and hydrogen evolution under alkaline electrolyte conditions.
[0110] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.
Claims
1. A method for preparing a graphene hollow sphere-supported nickel-manganese layered double hydroxide, characterized in that, Includes the following steps: (1) PS and GO were dispersed in water and mixed to obtain a PS-GO mixed solution. The mixture was stirred to obtain the reaction product. (2) The reaction product is calcined at 400~500℃ to obtain graphene hollow spheres SG; an inert atmosphere is introduced during the calcination process; (3) The SG is dispersed in an alcohol solvent, and nickel salt and manganese salt are added simultaneously to obtain a mixed solution, which is then heated for later use; the nickel salt is soluble in the alcohol solvent and provides Ni 2+ One or more of inorganic nickel salts and organic nickel salts, wherein the manganese salt is soluble in the alcohol solvent and provides Mn 2+ One or more of inorganic manganese salts and organic manganese salts; (4) Add HMT to the mixed solution and react to obtain graphene hollow spheres loaded with nickel-manganese layered double hydroxide.
2. The preparation method according to claim 1, characterized in that, The PS-GO mixed solution is dispersed in a solvent separately and then mixed, or PS and GO are dispersed in the same solvent sequentially and then mixed.
3. The preparation method according to claim 1 or 2, characterized in that, The mass-volume ratio of PS, GO, and solvent is (0.01~0.3g):(0.1~0.6g):(20~60mL).
4. The preparation method according to claim 3, characterized in that, The mass-volume ratio of PS, GO, and solvent is (0.03~0.2g):(0.1~0.5g):(30~50mL).
5. The preparation method according to claim 4, characterized in that, The mass-volume ratio of PS, GO, and solvent is (0.05~0.1g):(0.1~0.4g):(30~40mL).
6. The preparation method according to claim 1, characterized in that, The PS-GO mixed solution is subjected to a stirring reaction for 5 to 24 hours at a temperature of 20 to 40°C.
7. The preparation method according to claim 6, characterized in that, The PS-GO mixture solution is subjected to a stirring reaction for 8 to 20 hours.
8. The preparation method according to claim 7, characterized in that, The PS-GO mixture solution is subjected to a stirring reaction for 10-15 hours.
9. The preparation method according to claim 6, characterized in that, The PS-GO mixed solution is stirred and reacted at a temperature of 20~30℃.
10. The preparation method according to claim 1, characterized in that, The calcination time in step (2) is 0.5~8 h.
11. The preparation method according to claim 10, characterized in that, The calcination time in step (2) is 1 to 6 hours.
12. The preparation method according to claim 11, characterized in that, The calcination time in step (2) is 2 to 5 hours.
13. The preparation method according to claim 1, characterized in that, The nickel salt is one or more of nickel chloride, nickel nitrate, nickel acetate, nickel sulfate, and nickel sulfite; the manganese salt is one or more of manganese chloride, manganese nitrate, manganese acetate, and manganese sulfate.
14. The preparation method according to claim 1, characterized in that, The mass-to-volume ratio of the SG, nickel salt, manganese salt, and alcohol solution is (0.01~0.2g):(0.1~1g):(0.01~0.5g):(10~100mL); for every 1g of SG, the amount of HMT used is 1~100g.
15. The preparation method according to claim 14, characterized in that, The mass-to-volume ratio of SG, nickel salt, manganese salt, and alcohol solution is (0.01~0.1g):(0.2~1g):(0.02~0.4g):(20~80mL).
16. The preparation method according to claim 15, characterized in that, The mass-to-volume ratio of the SG, nickel salt, manganese salt, and alcohol solution is (0.01~0.08g):(0.2~0.8g):(0.05~0.2g):(40~60mL).
17. The preparation method according to claim 14, characterized in that, For every 1g SG, the amount of HMT used is 8~80g.
18. The preparation method according to claim 17, characterized in that, For every 1g SG, the amount of HMT used is 10~80g.
19. The preparation method according to claim 1, characterized in that, The reaction time in step (4) is 1~12 h; the reaction temperature is 60~150℃.
20. The preparation method according to claim 19, characterized in that, The reaction time in step (4) is 2 to 10 hours.
21. The preparation method according to claim 20, characterized in that, The reaction time in step (4) is 4 to 8 hours.
22. The preparation method according to claim 19, characterized in that, The reaction temperature in step (4) is 60~100℃.
23. The preparation method according to claim 22, characterized in that, The reaction temperature in step (4) is selected from 60℃, 70℃, 80℃, and 90℃.
24. A graphene hollow sphere-supported nickel-manganese layered double hydroxide obtained by the preparation method of claim 1, characterized in that, This includes hollow graphene spheres and nickel-manganese layered double hydroxide nanosheets supported on them.
25. The graphene hollow sphere-supported nickel-manganese layered double hydroxide according to claim 24, characterized in that, The diameter of graphene hollow spheres is 200-1200 nm.
26. The graphene hollow sphere-supported nickel-manganese layered double hydroxide according to claim 25, characterized in that, The diameter of graphene hollow spheres is 400-1000 nm.
27. The graphene hollow sphere-supported nickel-manganese layered double hydroxide according to claim 26, characterized in that, The diameter of the graphene hollow spheres is 500-800 nm.
28. The graphene hollow sphere-supported nickel-manganese layered double hydroxide according to claim 27, characterized in that, The diameter of the graphene hollow spheres is 600-700 nm.
29. An application of the graphene hollow spheres supported on nickel-manganese layered double hydroxide as described in claim 24, characterized in that, The graphene hollow spheres supporting nickel-manganese layered double hydroxide are used to prepare a catalyst for hydrogen production by water electrolysis.