A method for high-yield preparation of MXene quantum dots and application thereof

Abstract

The present application relates to a kind of MXene quantum dots and its high-yield preparation method and application, preparation method includes the following steps: S1: using etchant and intercalation agent to MAX phase material is handled to prepare MXene nanosheet;S2: using oxidizing agent and acid etchant to MXene nanosheet processing preparation porous / mesoporous MXene nanosheet;S3: porous / mesoporous MXene nanosheet is broken under protective atmosphere processing, to prepare the MXene quantum dots obtained.Therefore, the present application can solve the problems of low yield and difficult separation in the preparation of MXene quantum dots compared with the prior art, and the prepared MXene can be applied in the fields of biomedical, electrocatalysis, supercapacitor and battery.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, and in particular to an MXene quantum dot and its high-yield preparation method and application. Background Technology

[0002] MXenes are a novel class of two-dimensional layered metal carbides or metal nitrides discovered in 2011 by Professor Yury Gogosti's research group at Drexel University. Their general chemical formula is M... n+1 X n T x In this context, M represents an early transition metal, such as Ti, Zr, V, Nb, Ta, or Mo; X represents C or N; and T represents -O, -OH, or -F. MXene is generally obtained by selectively removing Al from MAX-phase ceramics through etching. This preparation method generates functional groups including -O, -OH, -F, -Br, -I, and -S on the surface of MXene, forming a sandwich-like structure. This unique structure endows MXene with high electrical conductivity, liquid-phase processing performance, tunable surface functions, and excellent mechanical properties, leading to its extensive research in energy storage, electromagnetic shielding, optoelectronics, seawater desalination, catalysis, and biomedicine. When MXene is fabricated into quantum dots, the dramatic reduction in its lateral dimensions increases its surface area and generates unique edge effects and quantum confinement effects, significantly enhancing its performance and making it highly promising for applications in related fields.

[0003] However, current methods for producing MXene quantum dots mainly fall into two categories: ultrasonic-assisted mechanical cutting and hydrothermal / reflux-assisted chemical etching. Because MXene has very few defects, these two methods cannot effectively break down the entire MXene nanosheet; typically, only a small number of MXene quantum dots can be cut from the edges of the MXene sheet, resulting in a very low yield. Furthermore, the separation of MXene quantum dots from MXene nanosheets is a complex and time-consuming process, often making it difficult to separate the two effectively. Therefore, there is an urgent need to develop a simple and easy method to almost completely convert MXene into MXene quantum dots, thereby enabling the large-scale preparation of MXene quantum dots. Summary of the Invention

[0004] The purpose of this invention is to provide an MXene quantum dot and its high-yield preparation method and application.

[0005] The objective of this invention can be achieved through the following technical solution: a high-yield preparation method for MXene quantum dots, comprising the following steps:

[0006] S1: treating the MAX phase material with an etchant and an intercalation agent to prepare MXene nanosheets;

[0007] S2: treating the MXene nanosheets with an oxidizing agent and an acidic etchant to prepare porous / mesoporous MXene nanosheets;

[0008] S3: treating the porous / mesoporous MXene nanosheets under a protective atmosphere to prepare MXene quantum dots.

[0009] Preferably, step S1 treats the MAX phase material with an etchant and an intercalation agent in sequence to prepare MXene nanosheets.

[0010] Preferably, step S2 treats the MXene nanosheets with an oxidizing agent and an acidic etchant in sequence to prepare porous / mesoporous MXene nanosheets.

[0011] Preferably, the MAX phase material in step S1 comprises a composite of one or more of Ti2AlC, Ti3AlC2, Ti3ZnC2, Ti3SiC2, Ti3AlCN, V2AlC, Nb2AlC, Ta4AlC3, Ta2AlC and Mo2Ga2C; and the resulting MXene is a composite of one or more of Ti2CTx, Ti3C2Tx, Ti3CNTx, V2CTx, Nb2CTx, Ta4C3Tx, Ta2CTx and Mo2CTx. x x x x x x x x The MAX phase material used in the present application is rich in types and has highly adjustable physical and chemical properties, so that the derived MXene quantum dots can meet the needs of different fields and application scenarios.

[0012] Preferably, the etchant in step S1 comprises a composite of one or more of hydrofluoric acid, ammonium hydrogen fluoride, hydrochloric acid-lithium fluoride, hydrochloric acid-sodium fluoride, and hydrochloric acid-ammonium fluoride. The etchant used in the present application can effectively remove the A element in the MAX phase, thereby improving the yield of multi-layer MXene.

[0013] Preferably, the intercalation agent in step S1 comprises a composite of one or more of urea, dimethyl sulfoxide, isopropylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and cetyltrimethylammonium bromide. The intercalation agent used in the present application can effectively insert into the interlayer of multi-layer MXene, thereby expanding the interlayer spacing and improving the exfoliation efficiency.

[0014] ​​​​​​​The etching agent and intercalation agent of the present application are various, which is beneficial to reduce the production cost of MXene and MXene quantum dots.

[0015] Preferably, the oxidizing agent in step S2 comprises a composite of one or more of Fenton reagent, Fenton-like reagent.

[0016] Further preferably, the Fenton reagent comprises iron salt-H2O2, and the Fenton-like reagent is copper salt-H2O2, manganese salt-H2O2, nickel salt-H2O2 or cobalt salt-H2O2.

[0017] More preferably, in the Fenton reagent and Fenton-like reagent, the molar ratio of metal salt to hydrogen peroxide is 1:100-100:1.

[0018] The Fenton reagent and Fenton-like reagent used in the present application have high oxidation ability, which can realize uniform oxidation of the edges and basal planes of MXene nanosheets, is beneficial to the formation of uniform porous MXene, and promotes the conversion to MXene quantum dots. By optimizing the molar ratio of metal to hydrogen peroxide, the pore size and pore wall size of the porous MXene are adjusted, and then the size of the quantum dots is adjusted.

[0019] Preferably, the acid etchant in step S2 comprises a composite of one or more of hydrofluoric acid, acetic acid, hydrochloric acid, sulfuric acid and nitric acid.

[0020] Preferably, step S3 utilizes a non-oxidizing etchant to perform a crushing treatment on the porous MXene nanosheet in a protective atmosphere to prepare MXene quantum dots.

[0021] Further preferably, the non-oxidizing etchant comprises an organic strong base.

[0022] More preferably, the organic strong base comprises a composite of one or more of ethylenediamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide. The non-oxidizing etchant used in the present application has been proved to be effective in assisting the cutting of porous MXene to convert it into MXene quantum dots, thereby improving the yield of MXene quantum dots.

[0023] In the present application, it is also feasible not to use a non-oxidizing etchant.

[0024] Preferably, the protective atmosphere comprises a composite of one or more of nitrogen, argon and argon-hydrogen mixed gas. The inert gas atmosphere used in the present application can prevent the oxidation of MXene quantum dots and ensure the purity thereof.

[0025] Preferably, the crushing treatment in step S3 comprises a composite of one or more of ultrasonic crushing, ball milling and hydrothermal treatment.

[0026] Further preferably, the ultrasonic power is 10-2000 W, and the ultrasonic time is 0.5-20 h.

[0027] Further preferably, the ball milling rotation speed is 100-900 rpm, and the time is 0.5-20 h.

[0028] Further preferably, the hydrothermal temperature is 40-180 DEG C, and the time is 2-60 h.

[0029] The present application can cut the porous MXene into MXene quantum dots through the crushing treatment.

[0030] A MXene / metal oxide quantum dot is prepared by the high-yield preparation method.

[0031] A porous MXene is prepared by the high-yield preparation method.

[0032] A MXene quantum dot is prepared by the high-yield preparation method.

[0033] The MXene quantum dot is applied to the fields of biomedicine, electrocatalysis, supercapacitors and batteries.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] 1. The present application provides a high-yield preparation method of MXene quantum dots, which can solve the problems of low yield of MXene quantum dots and difficulty in separating MXene quantum dots from the MXene body.

[0036] 2. The preparation method of the present application uses porous MXene as the precursor of MXene quantum dots, and directly converts it almost completely into MXene quantum dots through the method of crushing, so as to realize the high-yield preparation of MXene quantum dots and large-scale production.

[0037] 3. The present application can synergistically promote the exfoliation of MXene through the method of etchant treatment and subsequent intercalation of intercalation agent, thereby improving the yield of MXene.

[0038] 4. The present application obtains porous MXene with in-plane pores and a large number of defects by using an oxidizing etchant, which is used as the precursor for preparing MXene quantum dots, so as to greatly improve the yield of MXene quantum dots.

[0039] 5. The present application uses non-oxidizing etchant to achieve chemical cutting effect, thereby promoting the conversion of porous MXene to MXene quantum dots;

[0040] 6. The method of the present application can achieve almost complete conversion of porous MXene to MXene quantum dots, and can promote the separation step of MXene quantum dots and a small amount of unbroken nanosheets;

[0041] 7. The MXene quantum dots prepared by the present application can be well dispersed with various solvents, which is convenient for later processing and lays a foundation for its application in the fields of biomedicine, energy storage and conversion, etc. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a flow chart of the high-yield preparation method of MXene quantum dots of the present application;

[0043] Figure 2 is a transmission electron microscope image of MXene / metal oxide quantum dots prepared in Example 1;

[0044] Figure 3 is a transmission electron microscope image of porous MXene prepared in Example 1;

[0045] Figure 4 is a transmission electron microscope image of MXene quantum dots prepared in Example 1. DETAILED DESCRIPTION

[0046] The present application will be described in detail below in conjunction with the drawings and specific examples. The present embodiment is implemented on the premise of the technical solution of the present application, and gives detailed implementation mode and specific operation process, but the protection scope of the present application is not limited to the following examples.

[0047] A high-yield preparation method of MXene quantum dots, as shown in Figure 1 , comprises the following steps:

[0048] S1: etching and intercalation to prepare MXene nanosheets;

[0049] S2: oxidation and etching to prepare MXene-metal oxide quantum dot nanosheets and porous MXene nanosheets;

[0050] S3: etching-assisted fragmentation to prepare MXene quantum dots.

[0051] The following will be described in detail in conjunction with specific examples:

[0052] Example 1

[0053] Ti3C2T x . The above-stacked Ti3C2T x was added into 20 mL dimethyl sulfoxide, stirred at room temperature for 18 h, then washed with water several times by centrifugation, dispersed in water, and sonicated for 1 h. The above solution was centrifuged at 3500 rpm for 20 min using a centrifuge to remove the lower stacked Ti3C2T x . The upper solution was centrifuged at 20000 rpm for 5 min to obtain Ti3C2T x nanosheets. Figure 2 . 50 mL of 4.0 mg / mL Ti3C2T x aqueous dispersion was taken, 1 mmol FeSO4 and 1 mmol H2O2 were added thereto, and the mixture was stirred at room temperature for 30 min. The supernatant was removed by centrifugation to obtain Ti3C2T x / TiO x quantum dot composite. Then, the product was dispersed in 60 mL of a solution containing 2.0 mL of 40% HF by centrifugation several times, and stirred at room temperature for 30 min. The upper precipitate was removed by centrifugation to obtain porous Ti3C2T x ( Figure 3 ). 25 mL of 4.0 mg / mL porous Ti3C2T x dispersion was taken, 2.0 mL of ethylenediamine was added thereto, and N2 was bubbled for 30 min. The product was obtained by sonication for 20 h using an ultrasonic instrument, and the yield was 90%. x quantum dots Figure 4 .

[0054] Example 2

[0055] 1.0 g of Nb2AlC was added to 20 mL of 40% HF. The mixture was transferred to a 55°C oil bath and stirred magnetically for 48 h. The reaction solution was washed by centrifugation to obtain stacked Nb2CT x . The above-stacked Nb2CT x was added into 20 mL of isopropylamine, stirred at room temperature for 18 h, then centrifuged and washed with water several times, and then transferred to an ultrasonic instrument and sonicated for 1 h. The above solution was centrifuged at 35000 rpm for 20 min using a centrifuge to remove the lower stacked Nb2CT x . The upper solution was centrifuged at 20000 rpm for 5 min to obtain Nb2CT x nanosheets. 50 mL of 4.0 mg / mL Nb2CT x ​aqueous dispersion was added 1.0 mmol CuSO4and 1.0 mmol H2O2, and magnetically stirred for 30 min at room temperature. The supernatant was then removed by centrifugation to obtain Nb2CT x / NbO x quantum dot composites. The composites were then washed several times by centrifugation and dispersed in 60 mL of a solution containing 1.0 mL of 40% HF, and magnetically stirred for 30 min at room temperature. The upper precipitate was removed by centrifugation to obtain porous Nb2CT x quantum dots. 30 mL of a 3 mg / mL dispersion of porous Nb2CT x was added 3 mL of tetramethylammonium hydroxide, and purged with Ar for 30 min. The Nb2CT x quantum dots were obtained by ultrasonication using a cell disrupter for 4 h, with a yield of 85%.

[0056] Example 3

[0057] 1.0 g of V2AlC was added to 20 mL of 40% HF. The mixture was transferred to a 55 °C oil bath and magnetically stirred for 72 h. The reaction solution was washed by centrifugation to obtain stacked V2CT x . The stacked V2CT x was added to 20 mL of tetrabutylammonium hydroxide, and stirred at room temperature for 18 h, then centrifuged and washed with water several times, and then transferred to an ultrasonic instrument and ultrasonicated for 1 h. The solution was centrifuged at 35000 rpm for 20 min using a centrifuge to remove the lower stacked V2CT x . The upper solution was centrifuged at 20000 rpm for 5 min to obtain V2CT x nanosheets. 60 mL of a 3.0 mg / mL aqueous dispersion of V2CT x was added 1.0 mmol CuSO4and 1.0 mmol H2O2, and magnetically stirred for 30 min at room temperature. The supernatant was then removed by centrifugation to obtain VCT x / VO x quantum dot composites. The composites were then washed several times by centrifugation and dispersed in 60 mL of a solution containing 2.0 mL of 40% HF, and magnetically stirred for 30 min at room temperature. The upper precipitate was removed by centrifugation to obtain porous V2CT x . 30 mL of a 3.0 mg / mL dispersion of porous V2CT x was added 3.0 mL of tetrapropylammonium hydroxide, and purged with N2for 30 min. The V2CT x quantum dots were obtained by hydrothermal treatment and ultrasonication for 72 h, with a yield of 95%.

[0058] The foregoing description of the embodiments has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Modifications and variations are possible in light of the above teachings or can be acquired from practice of the application. As well, the description is presented in the context of the preferred embodiments as a number of alternatives. It is not intended to limit the application to the precise form described.

Claims

1. A high-yield preparation method for MXene quantum dots, characterized in that, Includes the following steps: S1: MXene nanosheets were prepared by treating MAX phase materials with etchants and intercalation agents; S2: Porous MXene nanosheets were prepared by treating MXene nanosheets with oxidizing agents and acidic etchants; S3: Prepare MXene quantum dots by crushing porous MXene nanosheets under a protective atmosphere; Step S3 involves using a non-oxidizing etchant to break down porous MXene nanosheets under a protective atmosphere to prepare MXene quantum dots; The non-oxidizing corrosive agent includes strong organic bases.

2. The high-yield preparation method of MXene quantum dots according to claim 1, characterized in that, The MAX phase material in step S1 includes one or more of Ti2AlC, Ti3AlC2, Ti3ZnC2, Ti3SiC2, Ti3AlCN, V2AlC, Nb2AlC, Ta4AlC3, Ta2AlC, and Mo2Ga2C; the resulting MXene is Ti2CT. x Ti3C2T x Ti3CNT x V2CT x Nb2CT x Ta4C3T x Ta2CT x and Mo2CT x One or more of the following.

3. The high-yield preparation method of MXene quantum dots according to claim 1, characterized in that, The etching agent in step S1 includes one or more of hydrofluoric acid, ammonium bifluoride, lithium hydrochloride-fluoride, sodium hydrochloride-fluoride, and ammonium hydrochloride-fluoride; The intercalating agent includes one or more of urea, dimethyl sulfoxide, isopropylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and hexadecyltrimethylammonium bromide, or a combination thereof.

4. The high-yield preparation method of MXene quantum dots according to claim 1, characterized in that, The oxidant in step S2 includes one or more of Fenton reagents and Fenton-like reagents.

5. The high-yield preparation method of MXene quantum dots according to claim 4, characterized in that, The Fenton reagent includes iron salt-H2O2, and Fenton-like reagents include copper salt-H2O2, manganese salt-H2O2, nickel salt-H2O2 or cobalt salt-H2O2, wherein the molar ratio of metal salt to hydrogen peroxide is 1:100~100:

1.

6. The high-yield preparation method of MXene quantum dots according to claim 1, characterized in that, The acidic etching agent in step S2 includes one or more of hydrofluoric acid, acetic acid, hydrochloric acid, sulfuric acid, and nitric acid, or a combination thereof.

7. The high-yield preparation method of MXene quantum dots according to claim 1, characterized in that, The organic strong base includes one or more of ethylenediamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, or a combination thereof.

8. The high-yield preparation method of MXene quantum dots according to claim 1, characterized in that, The crushing treatment method described in step S3 includes one or more of ultrasonic crushing, ball milling, and hydrothermal treatment; during ultrasonic crushing, the ultrasonic power is 10-2000 W and the ultrasonic time is 0.5-20 h; during ball milling, the ball milling speed is 100-900 rpm and the time is 0.5-20 h; during hydrothermal treatment, the temperature is 40-180℃ and the time is 2-60 h.

9. An MXene quantum dot, characterized in that, It is prepared by the high-yield preparation method according to any one of claims 1 to 8.

10. An application of the MXene quantum dot according to claim 9, characterized in that, The MXene quantum dots can be applied to the fields of biomedicine, electrocatalysis, supercapacitors, and batteries.

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