Hydro-terminated MXene and preparation method and application thereof

Abstract

The application discloses a hydrogen end group MXene and a preparation method and application thereof, and belongs to the field of frontier new material preparation technology, and is based on deprotonation-driven controllable editing of organic / inorganic end groups on the surface of MXene. The key hydrogen end group MXene is prepared by rapidly reducing Ti3C2Cl2 in a lithium / ethylenediamine electron salt solution at room temperature. Thanks to the relatively low bond dissociation energy of the surface Ti-H bond, the post-processing modification of the synthesized Ti3C2H x is thermodynamically favorable, and can be covalently edited by more than ten inorganic or organic groups (including -O, -S, -Se, -N, carboxylic acid, sulfonic acid, alcohol and amine).

Description

Technical Field

[0001] This invention relates to the field of cutting-edge new material preparation technology, and in particular to a hydrogen-terminated MXene, its preparation method and application. Background Technology

[0002] MXenes are a rapidly developing class of two-dimensional (2D) materials composed of transition metal carbides, nitrides, or carbonitrides. Their excellent electrical conductivity, large specific surface area, and outstanding solution processing properties have attracted widespread attention in various application areas such as supercapacitors, batteries, electrocatalysis, electromagnetic shielding, and sensors. The general formula for MXenes is M... n+1 X n T x (n=1~4), composed of n+1 layers of transition metal M (such as Ti, Zr, V, Nb, Ta, Mo) and n layers of X atoms (C or N). The outermost metal layer consists of surface groups T such as -O, -F, -Br, and -Cl. x Functional modification is performed. Surface end group T x MXenes possess the ability to reshape the structural diversity and functionality of MXenes. For example, theoretical studies predict that intrinsic MXene frameworks without surface end groups exhibit metallic conductivity, where delocalized d-orbital electrons of transition metal atoms are the dominant charge carriers. Introducing surface end groups affects the density of states and Fermi level of MXenes, transforming them from metallic to semiconducting. Therefore, precise control of MXene surface chemistry is of great significance, as it directly relates to the material properties required for various practical applications. To date, the surface end group modulation of MXenes has only been achieved through thermodynamically driven substitution reactions in molten salts, such as replacing -Br or -Cl end groups with chalcogenide (-O, -S, -Se, -Te) and amino (-NH2) functional groups. However, the strong chemical bonds inherent in the MXene surface (such as Ti-F, Ti-O, Ti-Cl) pose a challenge to these post-synthetic modifications, typically requiring harsh conditions such as high temperatures and extended reaction times. Furthermore, from a thermodynamic perspective, the covalent bonds in pristine MXenes tend to evolve into stronger chemical bonds (ΔG<0) rather than relax into lower energy states (ΔG>0), which limits the application of terminal substitution strategies. Therefore, the effective control of MXene end groups has always been a research challenge in this field. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art by providing a hydrogen-terminated MXene, its preparation method, and its application.

[0004] By employing a deprotonation strategy to achieve directional transformation of MXene surface end groups, a series of MXene materials with novel organic / inorganic end group structures were successfully prepared. Specifically, one such material is a hydrogen-terminated MXene (Ti3C2H). x As a multifunctional platform capable of modulating the surface chemistry of MXene, it achieves this function through a deprotonation reaction. This Ti3C2H... x Ti3C2Cl2 can be synthesized by reducing Ti3C2Cl2 in an electron-salt solution containing lithium / ethylenediamine within a rapid timescale (1–5 minutes) under ambient temperature and pressure. The relatively low bond dissociation energy of the Ti-H bond allows hydrogen to be exchanged with other functional groups. Notably, a series of inorganic and organic terminating groups (including -O, -S, -Se, -N, amines, carboxylic acids, sulfonic acids, and alcohols) have been successfully grafted onto the Ti3C2 surface. Furthermore, the effect of surface end groups on electrochemical hydrogen exchange has been systematically investigated. + The effects of storage. In particular, grafting redox-active ethylenediamine generates Ti3C2-EDA, which at 1 A·g -1 The specific capacitance under current is as high as 453.4 F·g -1 Furthermore, it exhibits excellent cycling stability over 5000 cycles. This ultrafast end-group editing strategy establishes a new paradigm for MXene surface chemical engineering, enabling precise control of MXene interface properties and opening up unprecedented opportunities for cutting-edge electrochemical applications.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] The technical concept of this application includes:

[0007] For the first time, hydrogen-terminated MXene (Ti3C2H) was successfully achieved. x The synthesis of MXene was achieved, and due to the relatively weak titanium-hydrogen (Ti-H) surface bonding, it can serve as a general platform for structural editing of MXene via deprotonation reactions, applicable to both organic and inorganic terminal modifications. This hydrogen-terminated Ti3C2H... x The precursor, at room temperature, is rapidly generated from molten salt-prepared Ti3C2Cl2 in a lithium / ethylenediamine electron salt solution within 1–5 minutes. Unlike traditional strong surface bonds, it exhibits a lower Ti-H bond dissociation energy (approximately 197 kJ·mol⁻¹). -1This allows for the easy and diverse covalent grafting of more than ten inorganic and organic functional groups (such as -O, -S, -Se, -N, amines, carboxylic acids, sulfonic acids, and alcohols) onto the MXene surface. Importantly, the surface end groups play a crucial role in proton storage of the Ti3C2MXene electrode in acidic aqueous electrolytes. Through covalent bonding with redox-active ethylenediamine (defined as Ti3C2-EDA), this electrode achieves proton storage at 1 A·g⁻¹. -1 Under these conditions, 453.4 F·g was achieved. -1 Excellent proton charge storage. Due to the large interlayer spacing (1.54 nm) and good electrolyte wettability provided by the -NH2 groups, the Ti3C2-EDA electrode also exhibits excellent rate performance and a long cycle life exceeding 5000 cycles. These results demonstrate a new paradigm for designing MXene surface chemistry and highlight the importance of surface end groups to their electrochemical performance.

[0008] The first aspect of the present invention is to provide a hydrogen-terminated MXene (Ti3C2H) x A method for preparing ), the method comprising the following steps:

[0009] Halogenated MXene is reduced in an electron salt solution, which removes the original halogen from the MXene. The active hydrogen in the electron salt solution is grafted onto the surface of Ti3C2 to form hydrogen-terminated Ti3C2, which is the hydrogen-terminated MXene.

[0010] Furthermore, the electron salt solution comprises lithium and ethylenediamine.

[0011] Furthermore, in the electron salt solution, the ratio of lithium to ethylenediamine is (40~60) mg: (15~25) mL.

[0012] Furthermore, the restoration time is 1 to 5 minutes.

[0013] Furthermore, the reduction is carried out at room temperature and pressure.

[0014] Furthermore, the halogenated MXene is selected from one or more of Ti3C2Cl2, Ti3C2Br2, and Ti3C2I2.

[0015] Furthermore, the ratio of the halogenated MXene to the ethylenediamine in the electron salt solution is (80~120) mg: (15~25) mL.

[0016] Furthermore, Ti3C2Cl2 is used in the synthesis of Ti3C2H. x The key precursor. The preparation method of the Ti3C2Cl2 includes the following steps:

[0017] First, Ti3AlC2 powder and CdCl2 (molar ratio 1:4) were mixed and thoroughly ground to obtain a homogeneous powder mixture. The resulting powder was then transferred to a tube furnace and calcined at 610–700 °C for 5–8 hours under an argon atmosphere. After the reaction, the product was washed with 37 wt% hydrochloric acid for 24 hours or more to remove impurities, finally yielding Ti3C2Cl2.

[0018] Furthermore, Ti3C2H x The synthesis was carried out in a lithium / ethylenediamine electron salt solution. The Ti3C2H x The preparation method includes the following steps:

[0019] The prepared Ti3C2Cl2 was added to ethylenediamine (preferably in a ratio of 100 mg to 20 mL), and the mixture was vigorously stirred to ensure uniform dispersion. Subsequently, lithium (preferably in a ratio of 50 mg to 20 mL) was added to the mixture, and the mixture immediately changed from transparent to blue, indicating the formation of solvated electrons. When the lithium completely dissolved (1–5 minutes), the Cl-terminal groups on the surface of Ti3C2Cl2 were completely converted to hydrogen-terminal groups, yielding Ti3C2H. x Contains Ti3C2H x The mixed solution was centrifuged and washed with tetrahydrofuran (THF) 3-5 times to completely remove residual ethylenediamine.

[0020] More preferably, Ti3C2Cl2 is synthesized by molten salt reaction of 1 gram of Ti3AlC2 powder and 3.74 grams of CdCl2 (molar ratio of 1:4).

[0021] More preferably, the synthesis conditions for Ti3C2Cl2 are calcination at 700 degrees Celsius for 5 hours.

[0022] More preferably, Ti3C2H x The process involved Ti3C2Cl2 in a lithium / ethylenediamine system at room temperature.

[0023] More preferably, the amounts of lithium and ethylenediamine are 50 mg and 20 ml, respectively.

[0024] More preferably, Ti3C2H x The reaction time in the lithium and ethylenediamine electron salt solution is 1 minute.

[0025] A second aspect of the present invention is to provide a hydrogen-terminated MXene, wherein the chemical formula of the hydrogen-terminated MXene is Ti3C2H. x (Ti3C2-H), where x is 1~2.

[0026] A third aspect of the present invention is to provide an application of hydrogen-terminated MXene, wherein the hydrogen-terminated Ti3C2 is used as a precursor and reacted with inorganic and / or organic compounds (such as hydrogen peroxide, sulfur powder, selenium powder, lithium nitride, organic amines, organic acids, organic alcohols, etc.) to perform surface end-group modification and transformation through a deprotonation process, so as to graft inorganic and / or organic end-groups onto the Ti3C2 surface.

[0027] Furthermore, the inorganic compound includes one or more of hydrogen peroxide, sulfur powder, selenium powder, lithium nitride, etc.

[0028] Furthermore, the organic compound includes one or more of organic amines, organic acids, organic alcohols, etc.

[0029] Furthermore, the inorganic end group includes one or more of -O, -S, -Se, and -N.

[0030] Furthermore, the organic end group includes one or more of amino, carboxylic acid, sulfonic acid, and hydroxyl groups.

[0031] Furthermore, inorganic end groups were grafted onto the surface of Ti3C2 to obtain Ti3C2 with inorganic end groups.

[0032] Furthermore, organic end groups were grafted onto the surface of Ti3C2 to obtain Ti3C2 with organic end groups.

[0033] Furthermore, when the inorganic end group is -S, Ti3C2S is prepared by reacting the hydrogen-terminated MXene with sulfur powder under vacuum calcination.

[0034] Furthermore, when the inorganic end group is -Se, Ti3C2Se is prepared by reacting the hydrogen-terminated MXene with selenium powder under vacuum calcination.

[0035] Furthermore, when the inorganic end group is -N, Ti3C2N is prepared by reacting the hydrogen-terminated MXene with lithium nitride under vacuum calcination.

[0036] Furthermore, when the inorganic end group is -O, Ti3C2O is prepared by reacting the hydrogen-terminated MXene with 1~3% hydrogen peroxide.

[0037] Furthermore, hydrogen-terminated MXenes were placed in an organic solvent at 100-140 °C. o Organically end-group Ti3C2 was prepared by solvothermal reaction at C for 20-28 hours.

[0038] Furthermore, the organic solvent includes one or more of trifluoroacetic acid, trifluoroethanol, methanesulfonic acid, ethylenediamine, propylenediamine, and butylenediamine.

[0039] Furthermore, the prepared Ti3C2H xAs a multifunctional platform, this method selectively converts hydrogen terminal groups into inorganic groups (-O, -S, -N, -Se) through a deprotonation reaction, ultimately yielding Ti3C2O, Ti3C2S, Ti3C2N, and Ti3C2Se, respectively. The steps include:

[0040] To generate Ti3C2S, mix 20 mg of sulfur powder with 80 mg of Ti3C2H. x The mixture was thoroughly mixed and then calcined at 400°C for 2 hours under vacuum. To prepare Ti3C2Se, 25 mg of selenium powder and 80 mg of Ti3C2H were mixed. x The mixture was thoroughly mixed and then subjected to the same treatment at 450°C for 2 hours. This was achieved by mixing 40 mg of Li3N powder and 80 mg of Ti3C2H... x After uniform mixing, Ti3C2N can be obtained by calcination at 500℃ for 2 hours. Ti3C2H... x Ti3C2O can be obtained by immersing the sample in a 1% H2O2 solution for 5 minutes and then treating it at room temperature.

[0041] More preferably, Ti3C2S is Ti3C2H x It was prepared by calcining sulfur powder at 400°C for 2 hours.

[0042] More preferably, Ti3C2S is Ti3C2H x It was prepared by calcining selenium powder at 450℃ for 2 hours.

[0043] More preferably, Ti3C2N is Ti3C2H. x It was prepared by treatment with 1% H2O2 solution.

[0044] More preferably, Ti3C2O is Ti3C2H x Prepared by calcining lithium nitride at 500°C for 2 hours.

[0045] Furthermore, the prepared Ti3C2H x As a multifunctional platform, this method selectively converts hydrogen-terminal groups into organic groups (organic amines, organic acids, and alcohols) through deprotonation reactions, ultimately yielding ethylenediamine-modified Ti3C2 (Ti3C2-EDA), trifluoroacetic acid-modified Ti3C2 (Ti3C2-TFA), methanesulfonic acid-modified Ti3C2 (Ti3C2-MSA), and trifluoroethanol-modified Ti3C2 (Ti3C2-TFE), respectively. The process includes the following steps:

[0046] A series of organic groups were grafted onto Ti3C2, including ethylenediamine (EDA), 1,3-diaminopropane (DPA), 1,4-butanediamine (BDA), diethylenetriamine (DTA), trifluoroacetic acid (TFA), trifluoroethanol (TFE), and methanesulfonic acid (MSA). Taking the synthesis of Ti3C2-EDA as an example, 80 mg of Ti3C2H... x The solution was transferred to a Schlenk tube containing 20 mL of ethylenediamine and then solvothermal treated at 120 °C for 24 hours under a nitrogen inert atmosphere. The resulting Ti3C2-EDA was then washed with formamide and ethanol and dried in a vacuum oven. The preparation of other Ti3C2s with organic terminal groups was accomplished by using different organic solvents instead of EDA in a similar manner.

[0047] More preferably, Ti3C2-EDA is Ti3C2H x Prepared by reacting with ethylenediamine solvent.

[0048] More preferably, Ti3C2-EDA is prepared under an inert atmosphere (such as nitrogen).

[0049] A fourth aspect of the present invention is to provide a trifluoroacetic acid-modified Ti3C2, wherein the trifluoroacetic acid-modified Ti3C2 is obtained by using hydrogen-terminated Ti3C2 as a precursor and performing surface end-group modification and transformation through a deprotonation process to graft trifluoroacetic acid groups onto the surface of Ti3C2 to obtain an organically end-grouped Ti3C2.

[0050] The fifth aspect of the present invention is to provide a methanesulfonic acid-modified Ti3C2, wherein the methanesulfonic acid-modified Ti3C2 is obtained by using hydrogen-terminated Ti3C2 as a precursor and performing surface end-group modification and transformation through a deprotonation process to graft methanesulfonic acid groups onto the surface of Ti3C2 to obtain an organically end-grouped Ti3C2.

[0051] The sixth aspect of the present invention is to provide a trifluoroethanol-modified Ti3C2, wherein the trifluoroethanol-modified Ti3C2 is obtained by using hydrogen-terminated Ti3C2 as a precursor and performing surface end-group modification and transformation through a deprotonation process to graft trifluoroethanol groups onto the surface of Ti3C2 to obtain an organically end-grouped Ti3C2.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1) This invention provides a hydrogen-terminated MXene, its preparation method, and its applications. This invention is the first to discover that hydrogen can be used as a terminal group grafted onto the surface of MXene, resulting in a novel MXene structure. Furthermore, the preparation of this hydrogen-terminated MXene only requires room temperature, significantly reducing reaction energy consumption and the need for demanding equipment compared to traditional molten salt nucleophilic substitution methods. Moreover, the preparation time of this hydrogen-terminated MXene is only 1 minute, greatly reduced compared to other traditional methods.

[0054] 2) This invention provides a hydrogen-terminated MXene, its preparation method, and its applications. This invention demonstrates that MXenes modified with almost any target inorganic or organic group can be prepared based on hydrogen-terminated MXenes. This is because Ti-H is the weakest Ti-group chemical bond. Furthermore, it achieves for the first time the preparation of various novel organic molecule-modified MXenes, such as Ti3C2 modified with trifluoroacetic acid, Ti3C2 modified with methanesulfonic acid, and Ti3C2 modified with trifluoroethanol.

[0055] 3) This invention provides a hydrogen-terminated MXene, its preparation method, and its application. The hydrogen-terminated MXene is prepared by rapid reduction of Ti3C2Cl2 in a lithium / ethylenediamine electron salt solution at room temperature. Benefiting from the relatively low bond dissociation energy of the surface Ti-H bonds, the synthesized Ti3C2H… x Post-processing modification is thermodynamically advantageous, enabling covalent editing via more than ten inorganic or organic groups, including -O, -S, -Se, -N, carboxylic acids, sulfonic acids, alcohols, and amines. Attached Figure Description

[0056] Figure 1 This diagram illustrates the synthesis of hydrogen-terminated MXene and demonstrates the controllable editing of organic / inorganic end groups on the MXene surface using a general deprotonation strategy. Here, 'a' represents the conversion of Ti3C2Cl2 to Ti3C2H. x a) Flowchart of Ti3C2 functionalized with organic / inorganic end groups; b) Schematic diagram and optical photograph of electron salt solution; c) Types of organic and inorganic groups modified on the surface of Ti3C2; d) Bond energy of Ti-based chemical bonds.

[0057] Figure 2 This is a schematic diagram of the synthesis of Ti3C2Cl2. In diagram a, a flowchart shows the synthesis of Ti3C2Cl2 from Ti3AlC2 via the molten salt method; in diagram b, a scanning electron microscope image and elemental mapping of the synthesized Ti3C2Cl2 are shown.

[0058] Figure 3 Ti3C2Cl2 and Ti3C2H x Characterization data. Where a represents Ti3C2Cl2 and Ti3C2H.x XRD data; b represents Ti3C2Cl2 and Ti3C2H x The Cl 2p spectrum.

[0059] Figure 4 Ti3C2Cl2 and Ti3C2H x The energy spectrum data curve.

[0060] Figure 5 Ti3C2H x Structural characterization data. Where a is a scanning electron microscope image; b is the solid image. 1 H is NMR; c is a high-angle annular dark-field scanning transmission electron microscopy image of the material cross section; d is the corresponding electron energy loss spectrum.

[0061] Figure 6 The energy spectrum curves are for Ti3C2O, Ti3C2S, Ti3C2N, and Ti3C2Se.

[0062] Figure 7 To make Ti3C2H x Structural characterization data of Ti3C2O, Ti3C2S, Ti3C2N, and Ti3C2Se were obtained. In the figures, a is a schematic diagram of the conversion process; b is the stoichiometric ratio of the prepared Ti3C2O, Ti3C2S, Ti3C2N, and Ti3C2Se; c is the O1s spectrum of Ti3C2O; d is the S 2p spectrum of Ti3C2S; e is the Se 3d spectrum of Ti3C2Se; f is the N 1s spectrum of Ti3C2N; g is the XRD data of Ti3C2S; h is the scanning electron microscope image of Ti3C2S and the corresponding elemental mapping distribution; i is the high-angle annular dark-field scanning transmission electron microscopy image of Ti3C2S; and j is the electron energy loss spectrum of Ti3C2S.

[0063] Figure 8 To make Ti3C2H x Structural characterization data of Ti3C2 converted to organic end groups. In the figures, a is a schematic diagram of the conversion process; b is all modified organic molecules; c is a scanning electron microscope image of Ti3C2-EDA and its corresponding elemental mapping distribution; d is a high-angle annular dark-field scanning transmission electron microscope image of Ti3C2-EDA; e is the electron energy loss spectrum of Ti3C2-EDA; f is the N 1s spectrum of Ti3C2-EDA; g is the F 1s spectrum of Ti3C2-TFA; h is the S 2p spectrum of Ti3C2-MSA; and i is the XRD data of Ti3C2 with all organic groups.

[0064] Figure 9 Ti3C2H xSynthesis mechanism and its deprotonation transformation mechanism. Where 'a' represents the conversion of Ti3C2Cl2 to Ti3C2H. x Mechanism process; bTi3C2H x The mechanism of conversion to organic amine modification of Ti3C2; c is Ti3C2H x The mechanism of conversion to organic sulfonic acid modification of Ti3C2; d is Ti3C2H x The mechanism of conversion to organic alcohol modification of Ti3C2; e is Ti3C2H x The mechanism of conversion to organic carboxylic acid modification of Ti3C2.

[0065] Figure 10 Electrochemical H of Ti3C2Cl2, Ti3C2O, and Ti3C2S + Storage performance. Among them, a is a comparison of cyclic voltammetry curves at a scan rate of 10 mV / s; b is a constant current charge-discharge curve at a current density of 1 A / g; c is an impedance curve.

[0066] Figure 11 Electrochemical H of Ti3C2-EDA, Ti3C2O-PDA, and Ti3C2-BDA + Storage performance. Among them, a is a flowchart; b is a comparison of cyclic voltammetry curves at 10 mV / s; c is a constant current charge-discharge curve at a current density of 1 A / g. Detailed Implementation

[0067] The present invention will now be described in detail with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Component models, material names, connection structures, control methods, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art. The technical solutions in 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.

[0068] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0069] In the examples below, unless otherwise specified, the reagents used are commercially available products and the methods employed are those known in the art.

[0070] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0071] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0072] Example 1

[0073] This embodiment provides a hydrogen-terminated MXene (Ti3C2H) x The preparation method of ) includes the following steps:

[0074] Step 1: Mix 1 gram of Ti3AlC2 powder (purchased from Kaixi Ceramics, 300 mesh) with 3.74 grams of CdCl2 (molar ratio 1:4) and grind thoroughly to obtain a homogeneous powder mixture. Then transfer the resulting powder to a tube furnace and calcine at 680°C for 8 hours under an argon atmosphere. After the reaction is complete, wash the product with 37wt% hydrochloric acid for 24 hours to remove impurities, thus obtaining Ti3C2Cl2.

[0075] Step 2, for Ti3C2H x The synthesis of [the substance] was carried out under ambient temperature and pressure conditions. 100 mg of prepared Ti3C2Cl2 was added to 20 mL of ethylenediamine, and the mixture was vigorously stirred at 900 rpm to ensure uniform dispersion, yielding a mixture. Subsequently, 50 mg of lithium was added to the mixture, and the color immediately changed from transparent to blue, indicating the formation of solvated electrons. After 1 minute, the lithium completely dissolved, resulting in a mixture containing Ti3C2H [substrate]. x A mixed dispersion containing Ti3C2H. x The mixed dispersion was centrifuged, the precipitate was collected, and washed four times with tetrahydrofuran (THF) to completely remove residual ethylenediamine, thus obtaining Ti3C2H. x .

[0076] Example 2

[0077] This embodiment provides a method for preparing Ti3C2 with inorganic end groups, including the following steps:

[0078] Step 1: For the synthesis of inorganic end-group Ti3C2, the Ti3C2H prepared by the preparation method in Example 1 was used. x It can be used as an effective precursor for selective nucleophilic transformation.

[0079] Step 2: To prepare Ti3C2S (purchased from Kaixi Ceramics, 300 mesh), mix 20 mg of sulfur powder with 80 mg of Ti3C2H. x Mix evenly, and then calcine at 420°C for 2 hours under vacuum.

[0080] Step 3: To prepare Ti3C2Se, mix 25 mg of selenium powder with 80 mg of Ti3C2H. x Mix evenly and calcine at 420°C under vacuum for 2 hours.

[0081] Step 4: Ti3C2N is produced by mixing 40 mg of Li3N powder with 80 mg of Ti3C2H. x The mixture was obtained by calcining at 420°C for 2 hours under vacuum conditions after uniform mixing.

[0082] Step 5: Ti3C2O is made by adding 80 mg of Ti3C2H x It is prepared by immersing in 10 ml of 1 wt% H2O2 solution and soaking for 5 minutes at room temperature.

[0083] Example 3

[0084] This embodiment provides a method for preparing Ti3C2 with organic end groups, including the following steps:

[0085] Step 1: For the synthesis of organic-terminated Ti3C2, the Ti3C2H prepared by the method in Example 1 was used. x It can serve as an effective precursor for selective transformation via deprotonation. A series of organic groups are grafted onto Ti3C2, including ethylenediamine (EDA), 1,3-diaminopropane (DPA), 1,4-butanediamine (BDA), diethylenetriamine (DTA), trifluoroacetic acid (TFA), trifluoroethanol (TFE), and methanesulfonic acid (MSA).

[0086] Step 2: For the synthesis of Ti3C2-EDA, 80 mg of Ti3C2H xThe sample was transferred to a Schlenk tube containing 20 mL of ethylenediamine and then heat-treated at 120 °C for 24 hours under a nitrogen atmosphere. The resulting Ti3C2-EDA was then washed sequentially with formamide and ethanol, and dried in a vacuum oven at 60 °C for 12 hours.

[0087] Step 3: Replace EDA with other organic acids, organic alcohols or organic amine solvents listed in Step 1 to prepare other organically capped Ti3C2 in the same manner, specifically including: Ti3C2-DPA, Ti3C2-BDA, Ti3C2-DTA, Ti3C2-TFA, Ti3C2-TFE, and Ti3C2-MSA.

[0088] Ti3C2H can be prepared according to the preparation methods of Examples 1 to 3. x Ti3C2 with various inorganic / organic end groups. The following sections characterize and analyze the various MXenes with different end groups prepared.

[0089] Demonstrates a novel hydrogen-terminated Ti3C2H x The synthesis of MXenes, and the relatively weak Ti-H surface bonds, can serve as a multifunctional platform for structural editing via deprotonation reactions applicable to both organic and inorganic end groups. Figure 1 a). This hydrogen-terminated Ti3C2H x It can be rapidly generated in about one minute in a lithium / ethylenediamine electron salt solution under normal temperature and pressure. Figure 1 b). Compared to traditional strong surface bonds, the Ti-H bond dissociation energy is lower (~197 kJ / mol). Figure 1 d) This makes it possible to easily and diversely graft more than a dozen inorganic and organic functional groups onto the MXene surface, such as -O, -S, -Se, -N, amines, carboxylic acids, sulfonic acids, and alcohols. Figure 1 c).

[0090] The Ti3C2Cl2 and Ti3C2H prepared in Example 1 x A series of structural characterizations were performed. For example... Figure 2 As shown in figure a, Ti3C2Cl2 was obtained by etching Ti3AlC2 powder in CdCl2 molten salt. The final Ti3C2Cl2 exhibits a distinct layered morphology with sizes in the micrometer range (μm). Figure 2 b). Elemental mapping tests confirmed the uniform distribution of Ti, C, and Cl. For example... Figure 2 As shown in figure a, Ti3C2Cl2 and Ti3C2H xThe (0002) diffraction peaks are located at 7.95° and 5.78°, respectively, indicating that the interlayer spacing has expanded from 1.11 nm to 1.52 nm. This expanded interlayer spacing is due to the insertion of solvated species during the removal of chlorine-terminated groups. Simultaneously, this expanded interlayer spacing facilitates the subsequent intercalation and covalent bonding of inorganic and organic functional groups. X-ray photoelectron spectroscopy was used to analyze the Ti3C2H... x The surface chemical state of Ti3C2Cl2 was examined. For pristine Ti3C2Cl2, characteristic peaks at 199.10 eV and 200.68 eV belong to Ti-Cl 2p3 / 2 and Ti-Cl 2p1 / 2, respectively. After treatment in the electrode-polarized solution, the characteristic Cl 2p peak disappeared, indicating that the chlorine end groups were completely removed. Figure 3 b). In Ti3C2H x In the energy dispersive spectroscopy test, no Cl signal was observed, which further proves the elimination of Cl. Figure 4 To demonstrate the presence of hydrogen-terminated groups, the Ti3C2H... x Solid 1 H NMR analysis. The chemical shift at 1.35 ppm is due to the Ti-H bonds on the Ti3C2 surface. Figure 5 b), which directly proves the presence of H-terminal groups on the surface. Ti3C2H x It still retains an ordered, layered morphology. Figure 5 a). By analyzing its cross-section using spherical aberration electron microscopy, it was found that Ti3C2H x The interlayer spacing is 1.51 nanometers ( Figure 5 c). Meanwhile, in the energy loss spectrum, only Ti and C signal peaks were found, with no other impurity elements detected. Due to the relatively low mass of hydrogen atoms, no corresponding hydrogen atom signal peak was observed in the experiment. These results all indicate the successful preparation of H-terminated MXene.

[0091] Example 2 uses Ti3C2H x Detailed structural analysis was performed on the inorganic end-group Ti3C2 precursor for preparation. Figure 6-7 ). Figure 6 The energy dispersive spectroscopy (EDS) curves for Ti3C2O, Ti3C2S, Ti3C2N, and Ti3C2Se are shown. The signal peaks for O, S, Se, and N confirm the successful conversion of the end groups. Elemental analysis revealed that the atomic ratios of the prepared Ti3C2O, Ti3C2S, Ti3C2N, and Ti3C2Se are all close to the ideal chemical formula ratios. Figure 7(b) To further confirm the presence of -O, -S, -Se, and -N end groups on the surface, X-ray photoelectron spectroscopy (XPS) was performed on the sample. In the high-resolution O 1s spectrum of Ti₃C₂O, characteristic peaks at 530.4 eV and 532.3 eV are consistent with those of Ti-O and C-Ti-O. x This indicates that surface-O functionalization has been successfully achieved. Figure 7 c). For Ti3C2S, the S 2p binding energies at 161.1 eV, 162.2 eV, and 163.9 eV belong to 2p3 / 2, 2p1 / 2, and S2, respectively. 2- ( Figure 7 d). For the high-resolution Se 3d spectrum of Ti3C2Se, the characteristic peaks at 52.8 eV and 54.4 eV are 3d5 / 2 and 3d3 / 2, respectively. Figure 7 e). In the case of Ti3C2N, the N 1s spectrum showed two nitrogen chemical states, including Ti-N (398.0 eV) and pyridine N (398.8 eV). Figure 7 f). Figure 7 g represents X-ray derived data for Ti3C2S. The diffraction peak at 7.1° is attributed to the (0002) crystal plane, indicating an interlayer spacing of 1.25 nm. Simultaneously, HAADF-STEM images of Ti3C2S show a layered structure with an interlayer spacing of 1.30 nm. Figure 7 This is consistent with the X-ray results. Furthermore, energy loss spectroscopy analysis of Ti3C2S showed only SL, CK, and Ti-L peaks. The absence of other impurity elements indicates a single S-terminal group. Area integrals of the peaks showed Ti, C, and S contents of 46 at%, 38 at%, and 15.9 at%, respectively. Figure 7 (j), which is consistent with the stoichiometry of Ti3C2S. These characteristics indicate that hydrogenated MXene is a versatile platform for the selective synthesis of a variety of inorganic surface functionalities.

[0092] Example 3 uses Ti3C2H x As a precursor, a detailed structural analysis was performed on the organically terminal Ti3C2 prepared by deprotonation reaction. Figure 8 Taking ethylenediamine-modified Ti3C2 as an example, such as... Figure 8 As shown in Figure c, the obtained Ti3C2-EDA exhibits a clear layered structure with uniform elemental distribution of Ti, C, and N. Furthermore, detailed XPS analysis was performed to investigate the surface chemical state and coordination structure after EDA covalent bonding. In the Ti 2p spectrum, a distinct Ti-N bond was observed at 458.3 eV, which is attributed to the covalent modification of the Ti atoms exposed on the MXene surface by EDA. Figure 8f). The interlayer gaps in Ti3C2-EDA can be directly detected using atomic resolution high-angle dark-field scanning transmission electron microscopy (HAADF-STEM). For example... Figure 8 As shown in d, the measured interlayer spacing of Ti3C2-EDA is 1.54 nm. In the electron energy loss spectroscopy test, the peaks at 284 eV, 401 eV, and 462 eV belong to CK, NK, and Ti-L, respectively, and the calculated carbon, nitrogen, and titanium contents are 46 at%, 16 at%, and 38 at%, respectively. Figure 8 e). X-ray photoelectron spectroscopy (XPS) was also performed on Ti3C2 modified with trifluoroacetic acid and methanesulfonic acid. Specifically, in the F 1s spectrum of Ti3C2-TFA (… Figure 8 The binding energy at 687.8 eV (g) is attributed to the -CF3 group. For the S 2p spectrum of Ti3C2-MSA ( Figure 8 (h) Three different S-binding modes were detected, including SC, S=O, and SO, indicating the presence of CH3SO3- groups. Simultaneously, due to the different sizes of the organic molecules, the interlayer spacing of MXene also showed a significant shift. Figure 8 i). The deprotonation mechanism of organic molecules was also analyzed. In the covalent modification of sulfonic acids, carboxylic acids, or organic alcohols, H2 is generated, leading to deprotonation, and ultimately the organic molecule ( Figure 9 ).

[0093] Electrochemical H of various end-group MXenes obtained in the implementation examples + Storage performance was tested. Compared to Ti3C2Cl2 containing only Cl groups, MXenes functionalized with inorganic end groups (such as Ti3C2O and Ti3C2S) exhibited significantly enhanced redox activity. At a current density of 1 A·g... -1 Under these conditions, Ti3C2O and Ti3C2S exhibit 313 F·g, respectively. -1 and 371 F·g -1 High specific capacitance ( Figure 10 This excellent electrochemical performance stems from the excellent compatibility of the -O and -S groups with the H2SO4 electrolyte, as well as the high redox activity of these end groups. Furthermore, the organically modified MXene exhibits distinct electrochemical plateaus in the galvanostatic charge-discharge (GCD) curves of Ti3C2-EDA, Ti3C2-PDA, and Ti3C2-BDA, which are consistent with the cyclic voltammetry (CV) curves, thus yielding 221.3 F·g⁻¹. -1 381.8 F·g -1 and 453.4 F·g -1 Specific capacitance ( Figure 11These findings all indicate that optimization of MXene end groups can achieve electrochemical H... + Storage performance tuning.

[0094] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0095] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0096] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Anyone skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the invention should still be covered by the claims of the invention. The above description of the embodiments is to facilitate understanding and use of the invention by those skilled in the art. Those skilled in the art can obviously easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the invention without departing from the scope of the invention should be within the protection scope of the invention.

Claims

1. A method for preparing hydrogen-terminated MXene, characterized in that, The preparation method includes the following steps: Halogenated MXene is reduced in an electron salt solution to remove the halogens from the MXene. The active hydrogen in the electron salt solution is grafted onto the surface of Ti3C2 to form hydrogen-terminated Ti3C2, which is the hydrogen-terminated MXene. The electronic salt solution comprises lithium and ethylenediamine; The halogenated MXene is selected from one or more of Ti3C2Cl2, Ti3C2Br2, and Ti3C2I2; The restoration time is 1-5 minutes; The reduction was carried out at room temperature and pressure; The chemical formula of the hydrogen-terminated MXene is Ti3C2H. x , where x is 1 to 2.

2. The preparation method according to claim 1, characterized in that, In the electron salt solution, the ratio of lithium to ethylenediamine is (40~60) mg: (15~25) mL; The ratio of the halogenated MXene to the ethylenediamine in the electronic salt solution is (80~120) mg: (15~25) mL.

3. A hydrogen-terminated MXene prepared by the preparation method according to any one of claims 1-2.

4. An application of a hydrogen-terminated MXene prepared by the preparation method according to any one of claims 1-2, characterized in that, Using the hydrogen-terminated MXene as a precursor, it reacts with inorganic and / or organic compounds, and through a deprotonation process, the surface end groups are modified and transformed to graft the inorganic and / or organic end groups onto the Ti3C2 surface.

5. The application according to claim 4, characterized in that, The inorganic end groups include one or more of -O, -S, -Se, and -N; The organic end group includes one or more of the following: amino group, carboxylic acid group, sulfonic acid group, and hydroxyl group; The inorganic compound includes one or more of hydrogen peroxide, sulfur powder, selenium powder, and lithium nitride; The organic compounds include one or more of organic amines, organic acids, and organic alcohols.

6. The application according to claim 5, characterized in that, When the inorganic end group is -S, Ti3C2S is prepared by reacting the hydrogen-terminated MXene with sulfur powder under vacuum calcination. When the inorganic end group is -Se, Ti3C2Se is prepared by reacting the hydrogen-terminated MXene with selenium powder under vacuum calcination. When the inorganic end group is -N, Ti3C2N is prepared by reacting the hydrogen-terminated MXene with lithium nitride under vacuum calcination. When the inorganic end group is -O, Ti3C2O is prepared by reacting the hydrogen-terminated MXene with 1~3% mass concentration of hydrogen peroxide.

7. The application according to claim 5, characterized in that, Place hydrogen-terminated MXene in an organic solvent at 100-140°C. o Organically end-group Ti3C2 was prepared by solvothermal reaction at C for 20-28 hours. The organic solvent includes one or more of trifluoroacetic acid, trifluoroethanol, methanesulfonic acid, ethylenediamine, propylenediamine, and butylenediamine.

8. A trifluoroacetic acid-modified Ti3C2, characterized in that, The trifluoroacetic acid-modified Ti3C2 is obtained by using hydrogen-terminated MXene prepared by any one of the preparation methods described in claims 1-2 as a precursor, and performing surface end-group modification and transformation through a deprotonation process to graft trifluoroacetic acid groups onto the surface of Ti3C2 to obtain Ti3C2 with organic end groups.

9. A mesylate-modified Ti3C2, characterized in that, The methanesulfonic acid-modified Ti3C2 is obtained by using hydrogen-terminated MXene prepared by any one of the preparation methods described in claims 1-2 as a precursor, and performing surface end-group modification and transformation through a deprotonation process to graft methanesulfonic acid groups onto the surface of Ti3C2 to obtain organically end-group Ti3C2.

10. A trifluoroethanol-modified Ti3C2, characterized in that, The trifluoroethanol-modified Ti3C2 is obtained by using hydrogen-terminated MXene prepared by any one of the preparation methods described in claims 1-2 as a precursor, and performing surface end-group modification and transformation through a deprotonation process to graft trifluoroethanol groups onto the surface of Ti3C2 to obtain Ti3C2 with organic end groups.

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