Partially oxidized Ti3C2TxMXene nanosheet for lubricant as well as preparation method and application of partially oxidized Ti3C2TxMXene nanosheet

Abstract

The invention provides a partially oxidized Ti3C2TxMXene nanosheet for a lubricant as well as a preparation method and application of the partially oxidized Ti3C2TxMXene nanosheet. The preparation method comprises the following steps: dissolving LiF powder in an HCl aqueous solution, adding Ti3AlC2 powder, fully dispersing, reacting, and centrifugally washing to obtain a Ti3C2Tx dispersion liquid; and adding a hydrogen peroxide aqueous solution, and carrying out oxidation treatment to obtain the partially oxidized Ti < 3 > C < 2 > T < x > MXene nanosheet for the lubricant. According to the method, the partially oxidized Ti < 3 > C < 2 > T < x > MXene nanosheet with a complete lamellar structure can be successfully prepared, the preparation method is simple, and the size of the nanosheet is controllable; the obtained partially oxidized Ti < 3 > C < 2 > T < x > MXene nanosheet has good lubricating performance when being applied to a lubricant.

Description

Technical Field

[0001] The present invention belongs to the field of lubricants, and specifically relates to a partially oxidized Ti3C2T x MXene nanosheets and their preparation methods and applications. Background Art

[0002] In the field of precision machinery in high-end manufacturing, the efficient and stable operation of parts and components is highly dependent on low-friction and highly wear-resistant materials. In microelectronics technology, the construction and operation of microcircuits inside chips place stringent requirements on the friction characteristics of materials in extremely small spaces. As the size of micro-nano devices continues to shrink, surface effects and friction and wear problems are becoming increasingly serious, significantly affecting their performance and life. However, traditional liquid lubricants have gradually exposed many limitations in the face of the demanding demands of these emerging fields. In extreme environments such as high temperature, high pressure or high vacuum, the performance of traditional lubricants will drop significantly or even fail completely; at the micro-nano scale, the molecular size of traditional lubricants is relatively large, making it difficult to effectively fill tiny gaps, and thus unable to achieve ideal lubrication effects.

[0003] Two-dimensional materials have shown significant advantages in the field of lubrication. Early studies have found that two-dimensional layered nanomaterials have significant anisotropy, which enables them to exhibit different physical properties in different directions, making it easy to precisely control them in specific applications; their high strength and high toughness ensure the structural integrity of the material under complex working conditions; their large specific surface area gives them excellent surface activity and adsorption capacity; and the weak interlayer van der Waals force and low shear strength enable these materials to slip between layers under the action of small external forces, showing excellent lubrication and friction reduction properties. Therefore, more and more researchers have begun to explore the application potential of two-dimensional materials in the field of lubrication. With the deepening of research, graphene, as the first two-dimensional material discovered, was first used in high-end lubricant formulations, significantly improving the lubrication performance. Since then, new two-dimensional materials such as transition metal chalcogenides and MXenes have been introduced into the research and development of lubricants, promoting the innovation and development of lubricating materials. At present, two-dimensional material-based lubricants have received widespread attention in the fields of automotive engines, aerospace precision parts, etc., and have become an important research direction.

[0004] MXenes are a class of two-dimensional layered transition metal carbides, nitrides or carbonitrides, and their chemical formula is usually expressed as M n+1 X n T x, where M is an early transition metal element (such as Ti, V, Mo, etc.); X is a carbon or nitrogen element; n is 1-3; T is a surface functional group (such as -OH, -F, -O, etc.), which is introduced during the preparation of MXenes. As an emerging member of two-dimensional layered materials, MXenes have opened up a new direction for tribological research with their unique crystal structure and chemical composition. It should be noted that MXenes sheets are prone to oxidation under atmospheric conditions. Although the spontaneous oxidation process of MXenes cannot be avoided, the MXene-TiO2 composite materials formed after oxidation have attracted widespread attention in the fields of sensors and energy storage. At present, the research on partially oxidized MXenes (O-MXenes) has made certain progress, but there are still many gaps and challenges in the field of lubricant applications.

[0005] Therefore, it is of great significance to develop a lubricant based on partially oxidized MXenes (O-MXenes) to further enrich the types of lubricants and improve the performance of lubricants. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a partially oxidized Ti3C2T x MXene nanosheets and their preparation method and application. The method of the present invention can successfully prepare partially oxidized Ti3C2T with complete sheet structure. x MXene nanosheets, the preparation method is simple, and the size of the nanosheets can be controlled; the obtained partially oxidized Ti3C2T x MXene nanosheets have good lubricating properties when used in lubricants.

[0007] The technical solution of the present invention is as follows:

[0008] Partially oxidized Ti3C2T for lubricant x MXene nanosheets, wherein the thickness of the nanosheets is 1-20 nanometers and the lateral size is 0.2-15 micrometers.

[0009] Preferably according to the present invention, the thickness of the nanosheet is 1.2-10 nanometers and the lateral size is 1-10 micrometers.

[0010] The above lubricant is partially oxidized Ti3C2T x A method for preparing MXene nanosheets comprises the following steps:

[0011] LiF powder was dissolved in HCl aqueous solution, Ti3AlC2 powder was added, fully dispersed, reacted, and centrifuged to obtain Ti3C2T x dispersion; adding hydrogen peroxide aqueous solution, and obtaining partially oxidized Ti3C2T for lubricant by oxidation treatment xMXene nanosheets.

[0012] Preferably, according to the present invention, the concentration of the HCl aqueous solution is 8-10 mol / L; and the volume ratio of the mass of the LiF powder to the HCl aqueous solution is 0.04-0.1 g / mL.

[0013] Preferably according to the present invention, the mass ratio of LiF powder to Ti3AlC2 powder is 1.5-1.8:1.

[0014] Preferably according to the present invention, the reaction temperature is 40-50° C., the reaction time is 16-30 h, and the reaction is carried out under stirring conditions.

[0015] According to the preferred embodiment of the present invention, the reaction solution obtained by the reaction is centrifuged and washed with deionized water until the pH value of the supernatant reaches 6-7, and the supernatant is collected to obtain Ti3C2T x Dispersion; centrifugal speed is 6000-10000rpm.

[0016] Preferably according to the present invention, the concentration of the aqueous hydrogen peroxide solution is 2-5 wt.%; the volume ratio of the aqueous hydrogen peroxide solution to the aqueous HCl solution is 1:1000-1:1500.

[0017] Preferably, according to the present invention, the temperature of the oxidation treatment is room temperature, the oxidation treatment is carried out under stirring conditions, the stirring rate is controlled at 500-800 rpm, and the stirring time is 25-60 min.

[0018] According to the preferred embodiment of the present invention, the reaction solution obtained by oxidation treatment is dried to obtain partially oxidized Ti3C2T x MXene nanosheets; the drying method is vacuum drying or freeze drying; the vacuum drying temperature is 30-50°C, and the vacuum drying time is 12-36 hours.

[0019] The above lubricant is partially oxidized Ti3C2T x Application of MXene nanosheets in lubricants. As lubricants, they can effectively reduce friction resistance and improve the stability and durability of the friction system.

[0020] Technical features and beneficial effects of the present invention:

[0021] 1. The method of the present invention first dissolves LiF powder in HCl aqueous solution, and fully disperses Ti3AlC2 powder in the solution. After the reaction, the exfoliation and conversion of Ti3AlC2 can be effectively promoted. Compared with samples that have not undergone similar treatment or other treatment methods, the Ti3C2T x The quality and quantity of nanosheets were significantly improved.

[0022] 2. In the preparation method of the present invention, the impurities generated during the reaction can be effectively removed by centrifugation and deionized water washing, and the pH value of the supernatant is neutral. x The purity of the nanosheets ensures that the final O-MXene has better performance and higher stability.

[0023] 3. The method of the present invention is to Ti3C2T x Hydrogen peroxide aqueous solution was added to the dispersion to achieve active oxidation and precisely control the Ti3C2T x Oxidation process of nanosheets. The final product O-MXene with specific activity obtained after partial oxidation has more surface functional groups, which provides a guarantee for its performance improvement in lubrication applications and can meet the requirements of product activity in different application scenarios.

[0024] 4. The O-MXene nanosheets prepared by the present invention have excellent lubrication properties. Experiments have shown that the O-MXene nanosheets obtained after H2O2 treatment have significantly improved friction coefficient, wear resistance, etc. compared with the original MXene, which provides a guarantee for its performance improvement in lubrication applications.

[0025] 5. The various conditions of the method of the present invention work together as a whole to achieve the excellent effect of the present invention. The present invention controls Ti3C2T x The preparation steps of the dispersion can adjust the pre-product Ti3C2T x The size and number of layers of the nanosheets can be controlled to achieve the controllability of their size and improve the quality of the nanosheets; at the same time, H2O2 oxidation treatment is used to obtain O-MXene with better lubrication performance, which is easy to implement in the laboratory and production, and has good repeatability and promotion. The friction coefficient of O-MXene obtained by experimental testing is as low as 0.01, which proves that the O-MXene prepared by the preparation method of the present invention has a lubricating effect. x It has potential practical application value in the field of micro-nano devices.

[0026] 6. In the preparation method of the present invention, the amount of hydrogen peroxide needs to be strictly controlled. If the amount of hydrogen peroxide is too high, the generated O-MXene will have too many mesopores. If it is further too high, it will affect the integrity of the nanosheets and cause material transformation, and may cause the TiO2 layer to be too thick, which will affect the friction properties of MXene, such as increasing the surface hardness and reducing the lubrication effect. If the amount of hydrogen peroxide is too low, the effect on the sample is weak, and it will not cause the active transformation. The surface may lack the necessary oxide protective layer, affecting the lubrication performance.

[0027] 7. The stirring rate and reaction time during the oxidation treatment in the present invention are very critical parameters. It is necessary to control the appropriate stirring rate and time to ensure that the oxidation reaction proceeds evenly and produce ideal oxidation products, thereby optimizing the tribological properties of the O-MXene material. A stirring rate that is too high or a time that is too long will lead to excessive oxidation and affect the properties of the material, while a stirring rate that is too low or a time that is too short may lead to insufficient oxidation and fail to achieve the expected lubrication performance. Therefore, the stirring conditions (rate and time) need to be optimized according to the specific experimental requirements.

[0028] 8. Ti3C2T of the present invention x The raw material ratio of LiF to Ti3AlC2 powder should be kept within a reasonable range during the dispersion preparation process. LiF and HCl solution are used to remove the aluminum layer in the MAX phase to expose the Ti3C2T x If the amount of LiF is too little, the aluminum layer is not completely removed, and the surface of MXene is not fully exposed, resulting in an incomplete structure or surface contamination. If the amount of LiF is too much, it will cause excessive corrosion, which will affect the oxidation reaction and lubrication performance of MXene. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The Ti3C2T prepared in Example 1 x Transmission electron microscope image of the nanosheet;

[0030] Figure 2 is a transmission electron microscope image of the O-MXene nanosheet prepared in Example 1;

[0031] Figure 3 This is an atomic force microscope image of the O-MXene nanosheet prepared in Example 1.

[0032] Figure 4 This is a friction force microscope image of the O-MXene nanosheet prepared in Example 1.

[0033] Figure 5 This is an atomic force microscope image of the O-MXene nanosheet prepared in Comparative Example 1.

[0034] Figure 6 This is a friction force microscope image of the O-MXene nanosheet prepared in Comparative Example 1. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the embodiments, but the present invention is not limited thereto.

[0036] The methods described in the examples are all conventional methods unless otherwise specified; the reagents used are all commercially available unless otherwise specified.

[0037] Example 1

[0038] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0039] At room temperature, add 10 ml of 9 mol / L HCl aqueous solution to a polytetrafluoroethylene beaker, then add 0.8 g of LiF powder and stir for 10 min to completely dissolve it. Then gradually add 0.5 g of MAX phase (Ti3AlC2) powder to the solution, fully disperse it, and stir the reaction in a water bath at 40 ° C for 24 hours. The obtained acidic product is centrifuged and washed with deionized water (centrifugal washing method: the acidic product is fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant is taken; the supernatant repeats the above centrifugal washing steps until the pH value of the supernatant reaches 6-7), and the supernatant is collected to obtain fresh dark green Ti3C2T x Then, 10 μl of 3 wt.% H2O2 aqueous solution was added and mixed, and stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize it, and partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets.

[0040] The lubricant prepared in this example is made of partially oxidized Ti3C2T x Transmission electron microscopy images of MXene nanosheets Figure 2 As shown in the AFM image, Figure 3 As shown, the friction force microscope image is Figure 4 As shown. The Ti3C2T prepared in this example x Transmission electron microscopy images of nanosheets are shown in Figure 2. Figure 1 As shown in the image, the original Ti3C2T x The nanosheet image shows the typical morphology of a flat single sheet. Then, the O-MXene nanosheet obtained after oxidation has some nanocrystalline TiO2 partially oxidized and degraded due to the addition of H2O2, and the amorphous carbon can promote the formation of a lubricating film that is prone to shearing during friction. The nanosheet obtained after oxidation has a thickness of 1.6nm and a lateral size of 2μm; compared with the original MXene, i.e., Ti3C2T x Compared with Ti3C2T nanosheets x The friction coefficient of the nanosheet is about 0.15, which has a smaller friction force and has a lubricating effect; the partially oxidized Ti3C2T x The friction coefficient of MXene nanosheets is as low as 0.01.

[0041] Example 2

[0042] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0043] At room temperature, add 15 ml of 9 mol / L HCl aqueous solution to a polytetrafluoroethylene beaker, add 0.7 g of LiF powder, and stir for 10 minutes to completely dissolve it. Then gradually add 0.4 g of MAX phase (Ti3AlC2) powder to the solution, fully disperse it, and stir the reaction in a water bath at 45 ° C for 18 hours. The obtained acidic product is centrifuged and washed with deionized water (centrifugal washing method: the acidic product is fully mixed with deionized water, centrifuged at 6000 rpm for 15 minutes, and the supernatant is taken; the supernatant repeats the above centrifugal washing steps until the pH value of the supernatant reaches 6-7), and the supernatant is collected to obtain fresh dark green Ti3C2T x Dispersion. 10 μl of 2 wt.% H2O2 aqueous solution was added to the dispersion and stirred at room temperature (stirring rate was 600 rpm) for 60 minutes to oxidize it. Partially oxidized Ti3C2T x MXene nanosheet dispersion was further freeze-dried.

[0044] The partially oxidized Ti3C2T x The friction coefficient of MXene nanosheets is 0.02, showing good lubrication properties.

[0045] Example 3

[0046] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0047] At room temperature, add 10 ml of 10 mol / L HCl aqueous solution to a polytetrafluoroethylene beaker, add 0.9 g of LiF powder, and stir for 12 minutes to completely dissolve it. Then, gradually add 0.6 g of MAX phase (Ti3AlC2) powder to the solution, fully disperse it, and stir the reaction in a water bath at 40 ° C for 22 hours. The obtained acidic product is centrifuged and washed with deionized water (centrifugal washing method: the acidic product is fully mixed with deionized water, centrifuged at 10000 rpm for 20 minutes, and the supernatant is taken; the supernatant repeats the above centrifugal washing steps until the pH value of the supernatant reaches 6-7), and the supernatant is collected to obtain a fresh dark green Ti3C2Tx dispersion. Add 10 μl of 4 wt.% H2O2 aqueous solution to the dispersion and stir at room temperature (stirring rate of 600 rpm) for 25 minutes to oxidize it. Partially oxidized Ti3C2Tx is obtained.x MXene nanosheet dispersion, further freeze-dried to obtain partially oxidized Ti3C2T x MXene nanosheets. Partially oxidized Ti3C2T x The friction coefficient of MXene nanosheets is 0.015, showing strong lubrication properties.

[0048] Example 4

[0049] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0050] At room temperature, add 10 ml of 9 mol / L HCl aqueous solution to a polytetrafluoroethylene beaker, add 1.0 g of LiF powder, and stir for 15 minutes to completely dissolve it. Then gradually add 0.6 g of MAX phase (Ti3AlC2) powder to the solution, fully disperse it, and stir the reaction in a water bath at 50 ° C for 20 hours. The obtained acidic product is centrifuged and washed with deionized water (centrifugal washing method: the acidic product is fully mixed with deionized water, centrifuged at 8000 rpm for 15 minutes, and the supernatant is taken; the supernatant repeats the above centrifugal washing steps until the pH value of the supernatant reaches 6-7), and the supernatant is collected to obtain a fresh dark green Ti3C2Tx dispersion. Add 10 μl of 4 wt.% H2O2 aqueous solution to the dispersion and stir at room temperature (stirring rate of 600 rpm) for 45 minutes to oxidize it. Partially oxidized Ti3C2Tx is obtained. x The MXene nanosheet dispersion was further freeze-dried. The partially oxidized Ti3C2T x The friction coefficient of MXene nanosheets is 0.02.

[0051] Example 5

[0052] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0053] At room temperature, 10 ml of 9 mol / L HCl aqueous solution was added to a polytetrafluoroethylene beaker, and then 0.9 g of LiF powder was added and stirred for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred at 40 ° C for 24 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain a fresh dark green Ti3C2Tx dispersion. Then 10 μl of 3 wt.% H2O2 aqueous solution was added and mixed, and stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize it to obtain partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets. Treated Ti3C2T x The friction coefficient of the nanosheet is 0.04.

[0054] Example 6

[0055] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0056] At room temperature, add 10 ml of 9 mol / L HCl aqueous solution to a polytetrafluoroethylene beaker, then add 0.8 g of LiF powder and stir for 10 min to completely dissolve it. Then gradually add 0.5 g of MAX phase (Ti3AlC2) powder to the solution, fully disperse it, and stir the reaction at 50 ° C for 30 hours. The obtained acidic product is centrifuged and washed with deionized water (centrifugal washing method: the acidic product is fully mixed with deionized water, centrifuged at 10000 rpm for 15 min, and the supernatant is taken; the supernatant repeats the above centrifugal washing steps until the pH value of the supernatant reaches 6-7), and the supernatant is collected to obtain a fresh dark green Ti3C2Tx dispersion. Then add 10 μl of 5 wt.% H2O2 aqueous solution to mix, and stir at room temperature (stirring rate is 600 rpm) for 30 min to oxidize it to obtain partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets. At this time, the treated Ti3C2T x The friction coefficient of the nanosheet is 0.03.

[0057] Example 7

[0058] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0059] At room temperature, 10 ml of 9 mol / L HCl aqueous solution was added to a polytetrafluoroethylene beaker, and then 0.8 g of LiF powder was added and stirred for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred at 40 ° C for 24 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 6000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain fresh dark green Ti3C2T x Then, 10 μl of 3 wt.% H2O2 aqueous solution was added and mixed, and stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize the Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x Mxene nanosheets.

[0060] This experiment used a relatively standard H2O2 concentration and reaction time, but due to the low centrifugal speed (6000rpm), the sample was not completely dispersed, and the nanosheets were prone to agglomeration, affecting the integrity and uniformity of the nanosheets. The surface oxidation was uneven, and the friction coefficient was high, measured at 0.06.

[0061] Comparative Example 1

[0062] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0063] At room temperature, 10 ml of 9 mol / L HCl aqueous solution was added to a polytetrafluoroethylene beaker, and then 0.8 g of LiF powder was added and stirred for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred at 40 ° C for 24 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain fresh dark green Ti3C2T xThen, 10 μL of 0.3 wt.% H2O2 aqueous solution was added and mixed, and the mixture was stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize the mixture, thereby obtaining partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets.

[0064] In this process, a lower concentration of H2O2 was used. The overall structure of the O-MXene flakes obtained after stirring was complete and the lateral size was large. However, the experimental test showed that Figure 5 Atomic force microscopy images of O-MXene sheets and Figure 6 The friction force microscope image obtained shows that no obvious oxidation process has occurred on the surface and no nanocrystalline TiO2 has been generated. As a result, although the integrity of the O-MXene flakes obtained in this process is normal, the friction force is poor compared to the experimental test, showing that the surface lubrication properties of the O-MXene nanosheets obtained are poor, and the friction coefficient is measured to be 0.1.

[0065] Comparative Example 2

[0066] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0067] At room temperature, 10 ml of 9 mol / L HCl aqueous solution was added to a polytetrafluoroethylene beaker, and then 0.8 g of LiF powder was added and stirred for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred at 40 ° C for 24 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain fresh dark green Ti3C2T x Then, 10 μl of 30 wt.% H2O2 aqueous solution was added and mixed, and the mixture was stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize the mixture, thereby obtaining partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets.

[0068] A higher concentration of H2O2 was used in this process. The overall structure of the O-MXene flakes obtained after stirring was relatively broken, and the lateral dimensions of the sample were smaller. Under the same experimental conditions, the integrity of the O-MXene flakes obtained in this process was lower than the lateral dimensions obtained by the preparation method of the present invention, and the generated TiO2 layer was too thick, resulting in increased surface hardness and reduced lubrication effect. The friction coefficient was measured to be 0.08.

[0069] Comparative Example 3

[0070] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0071] At room temperature, 10 ml of 9 mol / L HCl aqueous solution was added to a polytetrafluoroethylene beaker, and then 1.5 g of LiF powder was added and stirred for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred at 40 ° C for 24 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain fresh dark green Ti3C2T x Then, 10 μL of 3 wt.% H2O2 aqueous solution was added and mixed, and the mixture was stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize the mixture, thereby obtaining partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets.

[0072] Excessive LiF dosage in this process may lead to the x The surface of the nanosheet is over-fluorinated or over-etched, destroying its structural integrity. In this case, the friction coefficient is measured to be larger, 0.12.

[0073] Comparative Example 4

[0074] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0075] At room temperature, add 10 ml of 9 mol / L HCl aqueous solution to a polytetrafluoroethylene beaker, then add 0.4 g LiF powder and stir for 10 min to completely dissolve it. Then gradually add 0.5 g of MAX phase (Ti3AlC2) powder to the solution, fully disperse it, and stir the reaction at 40 ° C for 24 hours. The obtained acidic product is centrifuged and washed with deionized water (centrifugal washing method: the acidic product is fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant is taken; the supernatant repeats the above centrifugal washing steps until the pH value of the supernatant reaches 6-7), and the supernatant is collected to obtain fresh dark green Ti3C2T x Then, 10 μL of 3 wt.% H2O2 aqueous solution was added and mixed, and the mixture was stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize the mixture, thereby obtaining partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets.

[0076] In the comparative experiment, due to the small amount of LiF used, Ti3C2T x Due to incomplete MXene etching, poor dispersion, and insufficient lubricating film formation, the friction coefficient failed to decrease significantly, and the friction coefficient was measured to be 0.10.

[0077] Comparative Example 5

[0078] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0079] At room temperature, add 10 ml of 9 mol / L HCl aqueous solution to a polytetrafluoroethylene beaker, then add 0.8 g of LiF powder and stir for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred at 40 ° C for 35 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 12000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain fresh dark green Ti3C2T x Then, 10 μl of 3 wt.% H2O2 aqueous solution was added and mixed, and stirred at room temperature (stirring rate was 600 rpm) for 30 min to oxidize it, and partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T xMXene nanosheets.

[0080] In this comparative experiment, although the higher centrifugal speed (12000rpm) improves the dispersibility, the excessive centrifugal force may cause the nanosheets to break and destroy, thus affecting the uniformity of the sheet. The oxidation reaction time is long, resulting in the formation of too thick TiO2 layer, which increases the hardness of the sample and reduces the lubrication effect. The friction coefficient is measured to be 0.12, showing a significant gap with the lubrication performance of the present invention.

[0081] Comparative Example 6

[0082] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0083] At room temperature, 10 ml of 9 mol / L HCl aqueous solution was added to a polytetrafluoroethylene beaker, and then 0.8 g of LiF powder was added and stirred for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred in a water bath at 40 ° C for 24 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain fresh dark green Ti3C2T x Then, 10 μl of 3 wt.% H2O2 aqueous solution was added and mixed, and stirred at room temperature (stirring rate was 1000 rpm) for 30 min to oxidize the Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets.

[0084] In this comparative experiment, the stirring rate was increased to 1000 rpm, the oxidation reaction was more intense, and more uneven oxides or over-oxidation were formed, resulting in an unstable lubricating film, and the friction coefficient was measured to be 0.10.

[0085] Comparative Example 7

[0086] Partially oxidized Ti3C2T for lubricant x The preparation method of MXene (O-MXene) nanosheets is as follows:

[0087] At room temperature, 10 ml of 9 mol / L HCl aqueous solution was added to a polytetrafluoroethylene beaker, and then 0.8 g of LiF powder was added and stirred for 10 min to completely dissolve it. Subsequently, 0.5 g of MAX phase (Ti3AlC2) powder was gradually added to the solution, fully dispersed, and the reaction was stirred in a water bath at 40 ° C for 24 hours. The obtained acidic product was centrifuged and washed with deionized water (centrifugal washing method: the acidic product was fully mixed with deionized water, centrifuged at 8000 rpm for 15 min, and the supernatant was taken; the supernatant repeated the above centrifugal washing steps until the pH value of the supernatant reached 6-7), and the supernatant was collected to obtain fresh dark green Ti3C2T x Then, 10 μl of 3 wt.% H2O2 aqueous solution was added and mixed, and stirred at room temperature (stirring rate was 600 rpm) for 10 min to oxidize it, thereby obtaining partially oxidized Ti3C2T x MXene nanosheet dispersion. After further freeze drying, partially oxidized Ti3C2T x MXene nanosheets.

[0088] In this experiment, the reaction time was shortened to 10 minutes, and the friction coefficient of the incompletely oxidized nanosheet surface was relatively high, measured at 0.07.

Claims

1. A partially oxidized Ti3C2T3 lubricant x Mxene nanosheets, characterized in that The thickness of the nanosheet is 1-20 nanometers, and the lateral size is 0.2-15 micrometers.

2. The partially oxidized Ti3C2T2 lubricant according to claim 1 x Mxene nanosheets, characterized in that The nanosheets have a thickness of 1.2-10 nanometers and a lateral size of 1-10 micrometers.

3. The partially oxidized Ti3C2T2 lubricant as claimed in claim 1 or 2 x The preparation method of Mxene nanosheets comprises the following steps: LiF powder was dissolved in HCl aqueous solution, Ti3AlC2 powder was added, fully dispersed, reacted, and centrifuged to obtain Ti3C2T x dispersion; adding hydrogen peroxide aqueous solution, and obtaining partially oxidized Ti3C2T for lubricant by oxidation treatment x Mxene nanosheets.

4. The partially oxidized Ti3C2T3 lubricant according to claim 3 x The method for preparing Mxene nanosheets is characterized in that: The concentration of the HCl aqueous solution is 8-10 mol / L; the mass ratio of the LiF powder to the volume ratio of the HCl aqueous solution is 0.04-0.1 g / mL.

5. The partially oxidized Ti3C2T3 lubricant according to claim 3 x The method for preparing Mxene nanosheets is characterized in that: The mass ratio of LiF powder to Ti3AlC2 powder is 1.5-1.8:

1.

6. The partially oxidized Ti3C2T3 lubricant according to claim 3 x The method for preparing Mxene nanosheets is characterized in that: The reaction temperature is 40-50°C, the reaction time is 16-30h, and the reaction is carried out under stirring conditions.

7. The partially oxidized Ti3C2T3 lubricant according to claim 3 x The method for preparing Mxene nanosheets is characterized in that: The reaction solution was centrifuged and washed with deionized water until the pH value of the supernatant reached 6-7, and the supernatant was collected to obtain Ti3C2T x Dispersion; centrifugal speed is 6000-10000rpm.

8. The partially oxidized Ti3C2T3 lubricant according to claim 3 x The method for preparing Mxene nanosheets is characterized in that: The concentration of the aqueous hydrogen peroxide solution is 2-5 wt. %; the volume ratio of the aqueous hydrogen peroxide solution to the aqueous HCl solution is 1:1000-1:1500.

9. The partially oxidized Ti3C2T3 lubricant according to claim 3 x The method for preparing Mxene nanosheets is characterized in that: The temperature of the oxidation treatment is room temperature, and the oxidation treatment is carried out under stirring conditions, with the stirring rate controlled at 500-800 rpm and the stirring time being 25-60 min.

10. The partially oxidized Ti3C2T2 lubricant as claimed in claim 1 or 2 x Application of Mxene nanosheets in lubricants.

Images