Ti3C2T based on intercalation technology x MXene / CNTs, in-situ preparation method and use thereof

Abstract

This invention provides a Ti3C2T based on intercalation technology. x MXene / CNTs, their in-situ preparation methods, and applications are used to address existing Ti3C2T... x The preparation method of MXene / CNTs requires the dispersion of CNTs and CNTs with Ti3C2T. x The technical problem is that MXenes have poor interactions, resulting in CNTs growing only on dispersed layers and not between layers, or low density and non-uniform size of CNTs between layers. The preparation method includes the following steps: Step 1, preparing Ti3C2T x MXene; Step 2, apply Ti3C2T x MXene dispersed into NH4 + The mixture was stirred in an aqueous solution of inorganic salts, centrifuged, washed with water, and the precipitate was collected to obtain intercalated Ti3C2T. x MXene; Step 3: Insert the intercalated Ti3C2T x MXene was added to an inorganic salt solution containing iron, cobalt, or nickel, and stirred to obtain a reaction solution. The reaction solution was then subjected to solid-liquid separation, and the precipitate was collected. After drying, the precipitate was used to obtain iron, cobalt, or nickel-intercalated Ti3C2T. x MXene; Under an inert atmosphere, the resulting intercalated Ti3C2T x MXene was heat-treated with a carbon source to obtain Ti3C2T. x MXene / CNTs. CNTs grow in situ on and between adjacent lamellae, exhibiting dense growth and uniform size.

Description

Technical Field

[0001] This invention relates to two-dimensional layered materials, specifically to Ti3C2T based on intercalation technology. x MXene / CNTs, their in-situ preparation methods, and applications. Background Technology

[0002] Two-dimensional layered materials, such as graphene, phosphorene, silicene, boronene, germanene, transition metal dienes, and oxides, have attracted significant attention due to their high specific surface area and exceptional electronic, physical, chemical, optical, and mechanical properties. Because of their excellent structural stability and electrochemical performance, two-dimensional layered materials composed of two or more elements can be widely applied in numerous fields.

[0003] A novel class of two-dimensional layered materials, transition metal carbides and / or nitrides (MXenes), has attracted considerable attention since their discovery in 2011. The general formula for MXenes is M... n+1 X n T x Typically, it is formed by the corresponding mother M n+1 AX n MXenes are prepared by selective etching of the A-layer (e.g., Al, Si, Ga). Due to their tunable surface chemistry, excellent mechanical stability, metallic conductivity, electronic and magnetic properties, high hydrophilicity, and two-dimensional layered structure, MXenes have great application potential in rechargeable batteries, supercapacitors, catalysis, electromagnetic interference shielding, sensors, optics, and field-effect transistors. For example, in the field of electrochemical energy storage, MXene-based electrodes, characterized by high conductivity, large interlayer spacing, and low ion diffusion barriers, exhibit excellent performance in electrochemical capacitors and lithium / sodium-ion batteries. Ti3C2T x MXene is the most widely used and researched MXene material. However, similar to other two-dimensional layered materials, Ti3C2T... x The performance of MXene is still affected by its aggregation and stacking problem, which limits the transport of ions within the electrode, resulting in poor electrolyte wettability and slow ion diffusion.

[0004] To address the clustering and stacking issue and fully utilize the Ti3C2T x MXene performance in Ti3C2T lamellae x The strategy of introducing interlayer spacers in MXene has proven to be quite effective. Carbon nanotubes (CNTs), as interlayer spacers, can not only prevent the lamellar formation of Ti3C2T... x The effect of MXene interlayer stacking can further improve the performance of Ti3C2T sheets. xThe conductivity of MXene promotes the transfer of interlayer charges, making CNTs an ideal spacer material. Most current methods involve combining CNTs with Ti3C2T... x MXenes are directly mixed together, but this method has the following problems: CNTs need to be dispersed during the preparation process, but the dispersibility is poor, and there are issues with the mixing of CNTs and Ti3C2T. x The interaction between MXenes is poor. Additionally, some [issues] occur in Ti3C2T. x Methods for in-situ growth of CNTs on MXene have been developed, but these methods have the following problems: CNTs can only be grown on dispersed sheets, not between layers, or the density of CNTs between layers is low and the size is not uniform. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of existing Ti3C2T x The preparation method of MXene / CNTs requires the dispersion of CNTs and CNTs with Ti3C2T. x The technical problems of poor interaction between MXenes, or CNTs only growing on dispersed layers and not between layers, or low density and non-uniform size of CNTs between layers, provide the Ti3C2T intercalation technology. x MXene / CNTs, their in-situ preparation methods, and applications.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A Ti3C2T based on intercalation technology x MXene / CNTs are special in that:

[0008] The Ti3C2T x MXene / CNTs are composed of layered Ti3C2T x Composed of MXene and CNTs, with CNTs grown in situ on the Ti3C2T sheet. x MXene and adjacent Ti3C2T layers x Between MXenes, and CNTs exhibit apical growth.

[0009] Furthermore, the Ti3C2T x MXene / CNTs are made using NH4+. + Inorganic salts are intercalated to allow catalysts such as iron, cobalt, or nickel to enter the interlayer, and CNTs are grown by adding an external carbon source.

[0010] The present invention also provides the above-mentioned Ti3C2T based on intercalation technology. xThe in-situ preparation method of MXene / CNTs is characterized by the following steps:

[0011] Step 1: Preparation of Ti3C2T x MXene;

[0012] Step 2: Take the obtained Ti3C2T x MXene dispersed into NH4 + The mixture was stirred in an aqueous solution of inorganic salts, centrifuged, washed with water, and the precipitate was collected to obtain intercalated Ti3C2T. x MXene;

[0013] Step 3: Preparation of Ti3C2T x MXene / CNTs

[0014] Step 3.1: Insert the obtained intercalated Ti3C2T x MXene is added to an inorganic salt solution containing iron, cobalt, or nickel, and stirred to obtain a reaction solution;

[0015] Step 3.2: Perform solid-liquid separation on the reaction solution from Step 3.1, collect the precipitate, and dry the precipitate to obtain iron-, cobalt-, or nickel-intercalated Ti3C2T. x MXene;

[0016] Step 3.3: Under an inert atmosphere, insert the Ti3C2T intercalated in step 3.2. x MXene was heat-treated with a carbon source to obtain Ti3C2T. x MXene / CNTs.

[0017] Furthermore, step 1 specifically includes the following steps:

[0018] Step 1.1: Prepare a fluoride-containing solution;

[0019] Step 1.2: Add Ti3AlC2 to the obtained fluorine-containing solution and stir to obtain a reaction solution;

[0020] Step 1.3: Centrifuge the reaction solution from Step 1.2 and wash until neutral. Collect the precipitate to obtain Ti3C2T. x MXene.

[0021] Furthermore, in step 1.1:

[0022] The fluorine-containing solution is a hydrofluoric acid solution, a mixture of lithium fluoride and hydrochloric acid, an ammonium fluoride solution, an ammonium bifluoride solution, or a sodium bifluoride solution; wherein the concentration of fluoride ions is 2-22.5 mol / L;

[0023] Step 1.2 specifically involves adding Ti3AlC2 to the obtained fluorine-containing solution, wherein the mass ratio of Ti3AlC2 to the volume of the fluorine-containing solution is 0.01-0.5 g / mL, and stirring for 3-48 h to obtain the reaction solution.

[0024] Step 1.3 specifically involves centrifuging the reaction solution from step 1.2 at 1000-8000 rpm for 1-30 minutes, washing it with water, alcohol, or a mixture of alcohol and water in any ratio until neutral, collecting the precipitate to obtain Ti3C2T. x MXene;

[0025] Step 2 is as follows:

[0026] The obtained Ti3C2T x MXene dispersed into NH4 + Stir in an aqueous solution of inorganic salts for 12-48 hours, NH4 + The concentration of the extract was 1%-5%, centrifuged at 1000-8000 rpm for 1-10 min, washed with water, and the precipitate was collected to obtain intercalated Ti3C2T. x MXene; contains NH4 + The inorganic salt aqueous solution is an aqueous solution of ammonium chloride, ammonium sulfate, ammonium carbonate, ammonium nitrate, or ammonium phosphate;

[0027] Step 3.1 specifically involves:

[0028] The obtained intercalated Ti3C2T x MXene is added to a solution of nitrate, chloride, or sulfate containing iron, cobalt, or nickel, and stirred for 2-12 hours to obtain a reaction solution;

[0029] In step 3.2: the drying temperature is 40-120℃;

[0030] In step 3.3: the carbon source is the same as the Ti3C2T intercalated in step 3.2. x The mass ratio of MXene is 5:1-100:1; the carbon source is melamine, dicyandiamide, methane or acetylene; the heat treatment temperature is 600-1000℃ and the heat treatment time is 0.5-6h.

[0031] Further, step 3.1 specifically involves: inserting the obtained intercalated Ti3C2T... x MXene is added to an aqueous solution of cobalt nitrate, nickel nitrate, cobalt chloride, nickel chloride, or ferric sulfate, and stirred for 2-12 hours to obtain a reaction solution.

[0032] Furthermore, in step 1.1:

[0033] The fluorine-containing solution is a hydrofluoric acid solution; the concentration of fluoride ions is 22.5 mol / L.

[0034] Step 1.2 specifically involves adding Ti3AlC2 to the obtained hydrofluoric acid solution, with the mass ratio of Ti3AlC2 to the volume of hydrofluoric acid solution being 0.5 g / mL, and stirring for 3 hours to obtain the reaction solution.

[0035] Step 1.3 specifically involves centrifuging the reaction solution from step 1.2 at 1000 rpm for 20 minutes, washing it with a mixture of ethanol and water until neutral, collecting the precipitate, and obtaining Ti3C2T. x MXene;

[0036] Step 2 is as follows:

[0037] The obtained Ti3C2T x MXene was dispersed in an ammonium chloride aqueous solution and stirred for 12 hours. NH4 + The concentration was 5%, centrifuged at 1000 rpm for 1 min, washed with water, and the precipitate was collected to obtain intercalated Ti3C2T. x MXene;

[0038] Step 3.1 specifically involves:

[0039] The obtained intercalated Ti3C2T x MXene was added to a cobalt nitrate aqueous solution and stirred for 6 hours to obtain a reaction solution;

[0040] In step 3.2: the drying temperature is 60℃;

[0041] In step 3.3: dicyandiamide reacts with the intercalated Ti3C2T in step 3.2. x The mass ratio of MXene was 30:1; the heat treatment temperature was 800℃ and the heat treatment time was 3h.

[0042] The present invention also provides the above-mentioned Ti3C2T based on intercalation technology. x Applications of MXene / CNTs in energy conversion and storage, sensors, electromagnetic interference shielding, communications, optics, and actuators.

[0043] The present invention also provides the above-mentioned Ti3C2T based on intercalation technology. x Applications of MXene / CNTs in electrochemical energy storage.

[0044] The present invention also provides the above-mentioned Ti3C2T based on intercalation technology. x Application of MXene / CNTs in the preparation of sodium-ion battery anodes.

[0045] The beneficial effects of this invention are:

[0046] 1. The Ti3C2T provided by this inventionx MXene / CNTs, composed of layered Ti3C2T x It consists of MXene and CNTs. The CNTs are grown in situ on the layers and between adjacent layers, and the CNTs are grown in a top-growth mode, resulting in dense growth and uniform size. This is beneficial for direct use or further processing during later use to ensure that its performance meets the corresponding requirements and achieves the goal of efficient use. In addition, Ti3C2T x The CNTs in MXene / CNTs are obtained through in-situ growth, which is beneficial for realizing their superior performance and for their application in energy conversion and storage, sensors, electromagnetic interference shielding, communication, optics, and actuators.

[0047] 2. This invention uses an in-situ method to grow CNTs, through the presence of NH4+. + Inorganic salts expand the interlayer spacing, allowing more metal catalysts such as iron, cobalt, or nickel to enter the interlayer. Then, CNTs are grown using an external carbon source, thus filling the interlayer with CNTs and effectively preventing Ti3C2T. x Interlayer stacking of MXene. This in-situ preparation method does not require dispersion of CNTs during the preparation process, has a simple operation, mild preparation conditions, low cost, good reproducibility, and can integrate CNTs with Ti3C2T. x MXene exhibits tighter binding and better interaction, facilitating rapid charge transport between layers. It is stable and reliable, beneficial for large-scale applications, and offers broad economic and social benefits. Furthermore, to date, the use of MXene containing NH4... + Inorganic salt intercalation of Ti3C2T x No work has been reported on the in-situ growth of dense and uniformly sized CNTs between MXene layers, nor has it been reported in patents or literature. Attached Figure Description

[0048] Figure 1 This is the Ti3C2T prepared in Example 1 of the present invention. x SEM images of MXene / CNTs;

[0049] Figure 2 This is the Ti3C2T prepared in Example 1 of the present invention. x SEM images of MXene / CNTs at another magnification;

[0050] Figure 3 The intercalated Ti3C2T obtained in step 2 of embodiment one of the present invention x SEM image of MXene;

[0051] Figure 4 This is the Ti3C2T prepared in Example 1 of the present invention.x XRD diffraction patterns of MXene / CNTs;

[0052] Figure 5 The intercalated Ti3C2T obtained in step 2 of embodiment one of the present invention x TEM image of MXene;

[0053] Figure 6 This is the Ti3C2T prepared in Example 1 of the present invention. x TEM images of MXene / CNTs;

[0054] Figures 7-11 This is the Ti3C2T prepared in Example 1 of the present invention. x Element mapping graph of MXene / CNTs;

[0055] Figure 12 This is the Ti3C2T prepared in Example 1 of Embodiment 6 of the present invention. x Cycle performance diagram of sodium-ion battery with MXene / CNTs as the negative electrode and metallic sodium as the positive electrode. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Example 1

[0058] Ti3C2T based on intercalation technology x The in-situ preparation method of MXene / CNTs includes the following steps:

[0059] Step 1: Preparation of Ti3C2T x MXene

[0060] Step 1.1: Take 10 mL of a 22.5 mol / L hydrofluoric acid solution;

[0061] Step 1.2: Add 5g of Ti3AlC2 to hydrofluoric acid solution and stir for 3 hours to obtain the reaction solution;

[0062] Step 1.3: Centrifuge the reaction solution from Step 1.2 at 1000 rpm for 20 min, wash with a mixture of ethanol and water until neutral, collect the precipitate, and obtain Ti3C2T. x MXene.

[0063] Step 2: Take the Ti3C2T obtained in Step 1.3 x MXene dispersed into NH4 + The mixture was stirred in a 5% ammonium chloride aqueous solution for 12 hours, centrifuged at 1000 rpm for 1 minute, washed with water, and the precipitate was collected to obtain intercalated Ti3C2T. x MXene.

[0064] Step 3: Preparation of Ti3C2T x MXene / CNTs

[0065] Step 3.1: Insert the intercalated Ti3C2T obtained in Step 2 into the Ti3C2T layer. x MXene was added to a cobalt nitrate aqueous solution and stirred for 6 hours to obtain a reaction solution;

[0066] Step 3.2: Perform solid-liquid separation on the reaction solution from Step 3.1, collect the precipitate, and vacuum dry the precipitate at 60°C to obtain iron-, cobalt-, or nickel-intercalated Ti3C2T. x MXene;

[0067] Step 3.3: Under a nitrogen atmosphere, insert the Ti3C2T intercalated in step 3.2. x MXene and dicyandiamide were heat-treated at 800℃ for 3 hours to obtain Ti3C2T. x MXene / CNTs, wherein dicyandiamide is intercalated with Ti3C2T in step 3.2 x The mass ratio of MXene is 30:1.

[0068] like Figure 3 and Figure 5 As shown, the intercalated Ti3C2T obtained in step 2 can be seen x MXene already exhibits a distinct layered structure, but the interlayer spacing is relatively small, and there is some stacking. For example... Figure 6 As shown, after CNT growth, the interlayer spacing significantly increases, and dense CNTs are distributed both between layers and on the surface, with uniform CNT size. Figure 1 and Figure 2 As shown in the figure, the final Ti3C2T can be seen x MXene / CNTs are layered with very large interlayer spacing. Dense CNTs are distributed on the surface of the layers and between adjacent layers, and the CNTs are relatively uniform in size. Small particles, which are catalyst Co particles, can be seen at the top of the CNTs, indicating that the CNTs are grown from the top.

[0069] like Figure 4 As shown in the figure, the prepared Ti3C2T x MXene / CNTs are Ti3C2Tx It is composed of Co, C and TiN. The presence of TiN is due to the high nitrogen content in the carbon source dicyandiamide, which partially destroys Ti3C2T. x Nitriding produces a high-purity product that is not oxidized.

[0070] like Figures 7-11 As shown, Ti3C2T x MXene / CNTs are composed of C, Ti, O, N, and Co elements, with C, N, and O elements being almost uniformly distributed, and Ti element only present in Ti3C2T. x MXene is distributed in the sheet layer, while Co is only distributed in CNTs.

[0071] Example 2

[0072] The method steps in this embodiment are the same as those in Embodiment 1, with the difference being:

[0073] Step 1.1 specifically involves preparing 10 mL of a 10 mol / L ammonium bifluoride aqueous solution;

[0074] In step 1.2, 0.1 g of Ti3AlC2 was added to an aqueous solution of ammonium bifluoride and stirred for 24 h;

[0075] In step 1.3, the centrifugation speed is 3000 rpm, the centrifugation time is 30 min, and ethanol is used as the detergent.

[0076] In step 2, the Ti3C2T obtained in step 1.3 is... x MXene dispersed into NH4 + The mixture was stirred in a 2% ammonium sulfate aqueous solution for 36 hours, then centrifuged at 8000 rpm for 10 minutes.

[0077] In step 3.1, the intercalated Ti3C2T obtained in step 2 is... x MXene was added to the cobalt chloride aqueous solution and stirred for 2 hours;

[0078] In step 3.2, the drying temperature is 120℃;

[0079] In step 3.3, an argon atmosphere is used, and the carbon source is melamine. The melamine reacts with the Ti3C2T intercalated in step 3.2. x The mass ratio of MXene was 20:1, and the heat treatment time was 5 hours.

[0080] XRD, SEM, and TEM tests showed that the product obtained in this embodiment is Ti3C2T. x MXene / CNTs, high product purity, unoxidized. Ti3C2T xMXene / CNTs are lamellar in structure with very large interlayer spacing. Dense CNTs are distributed on the surface of the lamellar layers and between adjacent layers, and the CNTs are relatively uniform in size. Small particles, which are catalyst Co particles, are visible at the tips of the CNTs, indicating that the CNTs are grown from the tips. The composition consists of five elements: C, Ti, O, N, and Co. C, N, and O are almost uniformly distributed, while Ti is only present in Ti3C2T. x MXene is distributed in the sheet layer, while Co is only distributed in CNTs.

[0081] Example 3

[0082] The method steps in this embodiment are the same as those in Embodiment 1, with the difference being:

[0083] Step 1.1 specifically involves mixing 0.7g of LiF (lithium fluoride) with 5mL of 12M HCl and stirring until dissolved to obtain a fluorine-containing solution, wherein the fluoride ion concentration is 5.4mol / L; in other embodiments, the fluorine-containing solution can be prepared by mixing sodium fluoride / potassium fluoride / ferric fluoride with hydrochloric acid;

[0084] In step 1.2, 0.5g of Ti3AlC2 was added to the mixture of lithium fluoride and hydrochloric acid and stirred for 30h;

[0085] In step 1.3, the centrifugation speed is 5000 rpm, the centrifugation time is 6 min, and water is used as the detergent.

[0086] In step 2, the Ti3C2T obtained in step 1.3 is... x MXene dispersed into NH4 + The mixture was stirred in a 1% ammonium carbonate aqueous solution for 48 hours, then centrifuged at 5000 rpm for 6 minutes.

[0087] In step 3.1, the intercalated Ti3C2T obtained in step 2 is... x MXene was added to the ferric sulfate aqueous solution and stirred for 12 hours.

[0088] In step 3.3, the carbon source is methane, and the methane reacts with the Ti3C2T intercalated in step 3.2. x The mass ratio of MXene was 100:1, the heat treatment temperature was 600℃, and the heat treatment time was 6h.

[0089] XRD, SEM, and TEM tests showed that the product obtained in this embodiment is Ti3C2T. x MXene / CNTs, high product purity, unoxidized. Ti3C2T xMXene / CNTs are lamellar in structure with very large interlayer spacing. Dense CNTs are distributed on the surface of the lamellar layers and between adjacent layers, and the CNTs are relatively uniform in size. Small particles, which are catalyst Fe particles, are visible at the tips of the CNTs, indicating that the CNTs are grown from the tips. The composition consists of four elements: C, Ti, O, and Fe. C and O are almost uniformly distributed, while Ti is only present in Ti3C2T. x MXene is partially distributed in the sheet layer, while Fe is only distributed in CNTs.

[0090] Example 4

[0091] The method steps in this embodiment are the same as those in Embodiment 1, with the difference being:

[0092] Step 1.1 specifically involves dissolving 8g of ammonium fluoride in 10mL of water to prepare an ammonium fluoride solution, wherein the fluoride ion concentration is 21.6mol / L;

[0093] In step 1.2, 1g of Ti3AlC2 was added to the ammonium fluoride solution and stirred for 30h;

[0094] In step 1.3, the centrifugation speed is 5000 rpm, the centrifugation time is 15 min, and water is used as the detergent.

[0095] In step 2, the Ti3C2T obtained in step 1.3 is... x MXene dispersed into NH4 + Stir in a 2% ammonium nitrate aqueous solution for 24 hours, then centrifuge at 5000 rpm for 5 minutes.

[0096] In step 3.1, the intercalated Ti3C2T obtained in step 2 is... x MXene was added to the nickel nitrate aqueous solution;

[0097] In step 3.2, the drying temperature is 120℃;

[0098] In step 3.3, the carbon source is acetylene, and the acetylene reacts with the Ti3C2T intercalated in step 3.2. x The mass ratio of MXene was 80:1, and the heat treatment time was 5 hours.

[0099] XRD, SEM, and TEM tests showed that the product obtained in this embodiment is Ti3C2T. x MXene / CNTs, high product purity, unoxidized. Ti3C2T xMXene / CNTs are lamellar in structure with very large interlayer spacing. Dense CNTs are distributed on the surface of the lamellar layers and between adjacent layers, and the CNTs are relatively uniform in size. Small particles, which are Ni catalyst particles, are visible at the tips of the CNTs, indicating that the CNTs are grown from the tips. The composition consists of four elements: C, Ti, O, and Ni. C and O are almost uniformly distributed, while Ti is only present in Ti3C2T. x MXene is partially distributed in the sheets, while Ni is only distributed in CNTs.

[0100] Example 5

[0101] The method steps in this embodiment are the same as those in Embodiment 1, with the difference being:

[0102] Step 1.1 specifically involves preparing 10 mL of a 2 mol / L sodium hydrofluoric acid aqueous solution;

[0103] In step 1.2, 2g of Ti3AlC2 was added to an aqueous solution of sodium hydrofluoric acid and stirred for 48 hours;

[0104] In step 1.3, the centrifugation speed is 8000 rpm, the centrifugation time is 1 min, and water is used as the detergent.

[0105] In step 2, the Ti3C2T obtained in step 1.3 is... x MXene dispersed into NH4 + The mixture was stirred in a 2% ammonium phosphate aqueous solution for 36 hours, centrifuged at 3500 rpm for 5 minutes.

[0106] In step 3.1, the intercalated Ti3C2T obtained in step 2 is... x MXene was added to an aqueous solution of nickel chloride and stirred for 8 hours.

[0107] In step 3.2, the drying temperature is 40℃;

[0108] In step 3.3, under an argon atmosphere, the carbon source is melamine, and the melamine reacts with the Ti3C2T intercalated in step 3.2. x The mass ratio of MXene was 5:1, the heat treatment temperature was 1000℃, and the heat treatment time was 0.5h.

[0109] XRD, SEM, and TEM tests showed that the product obtained in this embodiment is Ti3C2T. x MXene / CNTs, high product purity, unoxidized. Ti3C2T xMXene / CNTs are lamellar in structure with very large interlayer spacing. Dense CNTs are distributed on the surface of the lamellar layers and between adjacent layers, and the CNTs are relatively uniform in size. Small particles, which are Ni catalyst particles, are visible at the tips of the CNTs, indicating that the CNTs are grown from the tips. The composition consists of five elements: C, Ti, O, N, and Ni. C, N, and O are almost uniformly distributed, while Ti is only present in Ti3C2T. x MXene is partially distributed in the sheets, while Ni is only distributed in CNTs.

[0110] Example 6

[0111] The Ti3C2T prepared in Example 1 x MXene / CNTs applied to sodium-ion batteries: the resulting Ti3C2T x MXene / CNTs, conductive carbon black, and polyvinylidene fluoride were mixed in a mass ratio of 7:2:1. After adding N-methylpyrrolidone and stirring until homogeneous, the mixture was coated onto copper foil and dried in a vacuum oven at 100°C for 12 hours to serve as the negative electrode. Sodium metal was used as the counter electrode, and a glass fiber filter membrane was used as the separator. 1 mol / L sodium hexafluorophosphate was dissolved in equal volumes of ethylene carbonate and dimethyl carbonate to serve as the electrolyte. A sodium-ion battery was assembled in a glove box filled with argon gas and where the water and oxygen content were both below 0.1 ppm. The battery performance was tested under the following conditions: voltage window 0.005-3V, and current density of 200 mA / g for cycle performance testing.

[0112] Figure 12 The graph shows the charge-discharge cycle performance of the sodium-ion battery obtained in this embodiment at a current density of 200 mA / g. As can be seen from the graph, after 50 cycles, the capacity is about 178 mAh / g and the coulombic efficiency is close to 100%.

[0113] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. Ti3C2T x MXene / CNTs in-situ preparation method, the Ti3C2T x MXene / CNTs is prepared by intercalation technology based on Ti3C2T x MXene and CNTs, wherein CNTs is in-situ grown on Ti3C2T x MXene and adjacent Ti3C2T x MXene, and CNTs is top growth mode; the Ti3C2T x MXene / CNTs is intercalated by inorganic salt containing NH4 + , so that catalyst iron, cobalt or nickel enters interlayer, and CNTs is obtained by external carbon source growth. characterized in that Comprising the following steps: Step 1, Preparation of Ti3C2T x MXene; Comprising the following steps: Step 1.1, configure a fluorine-containing solution; The fluorine-containing solution is a hydrofluoric acid solution, a lithium fluoride and hydrochloric acid mixture, an ammonium fluoride solution, an ammonium hydrogen fluoride solution or a sodium hydrogen fluoride solution; wherein the concentration of fluoride ions is 2-22.5 mol / L; Step 1.2, add Ti3AlC2 to the obtained fluorine-containing solution and stir to obtain a reaction solution; specifically: add Ti3AlC2 to the obtained fluorine-containing solution, the mass of Ti3AlC2 to the volume ratio of the fluorine-containing solution is 0.01-0.5 g / mL, and stir for 3-48 h to obtain a reaction solution; Step 1.

3. Centrifuge the reaction solution of step 1.2 and wash to neutral, collect the precipitate to obtain Ti3C2T x Mxene; Specifically: centrifuge the reaction solution of step 1.2 at 1000-8000 rpm for 1-30 min, and wash to neutral with water or alcohol or any ratio of alcohol and water mixture, collect the precipitate to obtain Ti3C2T x MXene; Step 2, the obtained Ti3C2T x MXene was dispersed into an aqueous solution containing NH4 + After stirring, centrifugation and water washing, the precipitate was collected to obtain intercalated Ti3C2T x MXene; specifically: The obtained Ti3C2T x MXene is dispersed into an aqueous solution of inorganic salt containing NH4 + , stirred for 12-48 h, and centrifuged at a speed of 1000-8000 rpm for 1-10 min, and the precipitate is collected after water washing to obtain intercalated Ti3C2T + MXene; the aqueous solution of inorganic salt containing NH4 x is an aqueous solution of ammonium chloride, ammonium sulfate, ammonium carbonate, ammonium nitrate or ammonium phosphate; and the concentration of NH4 + + is 1%-5%. Step 3, Preparation of Ti3C2T x MXene / CNTs Step 3.1, the obtained intercalated Ti3C2T x MXene is added to an inorganic salt solution containing iron, cobalt or nickel, and stirring obtains a reaction solution; specifically: The obtained intercalated Ti3C2T x MXene was added to a solution containing iron, cobalt or nickel nitrate, chloride or sulfate salt, and stirred for 2-12 h to obtain a reaction solution; Step 3.2, solid-liquid separation is performed on the reaction solution of step 3.1, the precipitate is collected, and the precipitate is dried to obtain an iron-, cobalt- or nickel-containing intercalated Ti3C2T x MXene; the temperature for drying is 40-120 ℃; Step 3.

3. The intercalated Ti3C2T of step 3.2 was heated with carbon source under inert atmosphere to obtain Ti3C2T x MXene was heated with carbon source to obtain Ti3C2T x MXene / CNTs; Carbon source and Ti3C2T intercalated in step 3.2 x The mass ratio of MXene is 5:1-100:1; the carbon source is melamine, dicyandiamide, methane or acetylene; the heat treatment temperature is 600-1000 ℃, and the heat treatment time is 0.5-6 h.

2. The Ti3C2T x MXene / CNTs in-situ preparation method, characterized in that, Step 3.1 is specifically: the obtained intercalated Ti3C2T x MXene is added to an aqueous solution of cobalt nitrate, nickel nitrate, cobalt chloride, nickel chloride or iron sulfate, and stirred for 2-12 h to obtain a reaction solution.

3. The Ti3C2T x MXene / CNTs in-situ preparation method, characterized in that, In step 1.1: The fluorine-containing solution is a hydrofluoric acid solution; wherein the concentration of fluoride ions is 22.5 mol / L; Step 1.2 specifically: add Ti3AlC2 to the obtained hydrofluoric acid solution, the mass of Ti3AlC2 to the volume ratio of the hydrofluoric acid solution is 0.5 g / mL, and stir for 3 h to obtain a reaction solution; Step 1.3 is specifically: centrifuging the reaction liquid of step 1.2 at a speed of 1000 revolutions per minute for 20 min, and washing to neutral with a mixture of ethanol and water, collecting the precipitate to obtain Ti3C2T x MXene; Step 2 specifically: The obtained Ti3C2T x MXene was dispersed into aqueous ammonium chloride solution and stirred for 12 h, NH4 + The concentration of the supernatant was 5%, and the precipitate was collected after centrifugation at 1000 rpm for 1 min and water washing, to obtain intercalated Ti3C2T x MXene; Step 3.1 specifically: The obtained intercalated Ti3C2T x MXene was added to the aqueous solution of cobalt nitrate, and stirred for 6 h to obtain a reaction solution; In step 3.2: the temperature of drying is 60 ℃; In Step 3.3: dicyandiamide with intercalated Ti3C2T from Step 3.2 x The mass ratio of MXene was 30:1; the heat treatment temperature was 800 ℃, and the heat treatment time was 3 h.

4. The Ti3C2T x MXene / CNTs in-situ preparation method prepared by Ti3C2T x Application of MXene / CNTs in the fields of energy conversion and storage, sensors, electromagnetic interference shielding, communication, optics, and drivers.

5. The Ti3C2T x MXene / CNTs in-situ preparation method prepared by Ti3C2T x Application of MXene / CNTs in electrochemical energy storage.

6. The Ti3C2T x MXene / CNTs in-situ preparation method prepared Ti3C2T x Application of MXene / CNTs in preparation of sodium ion battery negative electrode.

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