A functionalized carbon quantum dot and MXene composite lubricating material and preparation method thereof

Abstract

The invention discloses a functionalized carbon quantum dot and MXene composite lubricating material and a preparation method thereof. The preparation method comprises: dissolving urea and sodium hydroxide into acetaldehyde, mixing and stirring, ultrasonically treating, centrifugally washing to obtain NCQDs, dispersing the NCQDs in water to obtain an NCQDs dispersion; slowly adding Ti3AlC2 powder into hydrofluoric acid while stirring, isothermally stirring the obtained suspension for 48 to 72 hours, centrifugally washing the obtained product and vacuum drying it to obtain Ti3C2T x Powder; Ti3C2T prepared in step 2 x The powder was added to the NCQDs dispersion, stirred for 10 to 24 hours, and allowed to stand for 5 to 10 hours. The obtained product was centrifuged and freeze-dried to obtain NCQDs@Ti3C2T x Powder; prepare green and environmentally friendly functional carbon quantum dots and MXene composite lubricating materials with excellent anti-friction and anti-wear properties, with a simple reaction process and low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials and relates to a nano-composite lubricating material, and specifically relates to a functionalized carbon quantum dot and MXene composite lubricating material and a preparation method thereof. Background Art

[0002] Carbon quantum dots (CQDs) are spherical and / or quasi-spherical forms with a size less than 10 nm. They also have low toxicity, environmental friendliness, high chemical stability, thermal stability and good designability. They have various preparation methods and a wide range of raw materials. More specifically, the composition, structure, morphology and particle size of CQDs can be artificially designed and controlled by selecting appropriate precursor materials, functional reagents and synthesis methods. Generally, element-doped CQDs have been proven to be an effective method for functionalizing CQDs. Nitrogen, as an active atom, easily forms coordination bonds with metal elements and exhibits strong affinity on metal surfaces, thereby enhancing the formation of metal surface compounds to enhance the protective effect on the surface. Therefore, nitrogen-doped carbon quantum dots (NCQDs) can be designed and synthesized by surface functionalization to improve the chemical activity and dispersibility of additives, thereby promoting the adsorption performance of additives on friction surfaces. However, the tribological properties of lubricating materials need to be continuously improved to meet the requirements of rapid industrialization, and the improvement of lubrication performance through the composite of several materials has become an important means.

[0003] MXene is a new type of 2D transition metal carbon / nitride nanomaterial with the advantages of graphite-like multilayer structure, low shear strength, self-lubricating ability, high surface area and abundant active sites, which makes it widely concerned in lubricating materials. The unique weak van der Waals force between MXene layers makes it easy for them to slide relative to each other under shear force, and the surface also has abundant functional groups, which can make it easy to be functionalized to meet the desired performance in various friction environments. Therefore, NCQDs and Ti3C2Tx are composited to prepare lubricating materials, thereby improving the tribological properties of a single material. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a green and environmentally friendly functionalized carbon quantum dot and MXene composite lubricating material with excellent friction reduction and anti-wear properties and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a functionalized carbon quantum dot and MXene composite lubricating material comprises the following steps:

[0007] Step 1: Dissolve urea and sodium hydroxide in acetaldehyde in a mass ratio of 1:3:10, mix and stir for 1 to 2 hours, perform ultrasonic treatment for 1 hour, centrifuge and wash to obtain NCQDs, and disperse NCQDs in water to obtain a NCQDs dispersion with a mass concentration of 0.11 g / ml;

[0008] Step 2: Ti3AlC2 powder is slowly added to hydrofluoric acid at a mass ratio of 1:10 while stirring, and the resulting suspension is isothermally stirred for 48 to 72 hours. The resulting product is centrifugally washed and vacuum dried to obtain Ti3C2T x powder;

[0009] Step 3: Prepare NCQDs and Ti3C2T x The mass ratio of Ti3C2T prepared in step 2 is 2.2: (0.15-0.25). x The powder was added to the NCQDs dispersion, stirred for 10 to 24 hours, and allowed to stand for 5 to 10 hours. The obtained product was centrifuged and freeze-dried to obtain NCQDs@Ti3C2T x powder.

[0010] The present invention also has the following technical features:

[0011] Preferably, the centrifugal washing in step 1 is centrifugal washing with distilled water for 5 to 8 times.

[0012] Preferably, the centrifugal washing in step 2 is centrifugal washing with distilled water until the supernatant is neutral.

[0013] Preferably, the temperature of the isothermal stirring in step 2 is 25°C.

[0014] Preferably, the vacuum drying in step 2 is vacuum drying at 60° C. for 12 hours.

[0015] The present invention also protects a functionalized carbon quantum dot and MXene composite lubricating material prepared by the method as described above.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] The present invention first functionalizes CQDs, doping nitrogen into CQDs to form functionalized NCQDs, and then assembling NCQDs onto Ti3C2T x Among them, small-sized NCQDs can easily enter the Ti3C2T x The interlayer gap of Ti3C2T xThe surface functional groups of NCQDs interact with each other to form CO-Ti covalent bonds, making NCQDs rooted in Ti3C2T x Surface, forming NCQDs@Ti3C2T x Composite materials. NCQDs@Ti3C2T x The composite surface has more abundant functional groups, which enhances the NCQDs@Ti3C2T x The affinity of the composite material to the friction surface facilitates its adsorption on the friction surface; at the same time, under pressure and shear force, the unique spherical and layered structures work together, that is, Ti3C2T x Sliding occurs between the layers, converting the friction into internal friction between the layers, and the NCQDs nanoparticles can act as rolling bearings during the friction process, converting sliding into rolling. Therefore, the combined use of layered materials and spherical nanoparticles shows the synergistic lubrication effect of interlayer sliding and rolling bearing effect, effectively improving the tribological properties of a single material;

[0018] The reaction process of the present invention is simple, does not require large-scale equipment and harsh conditions, and NCQDs@Ti3C2T x As lubricating materials, composite materials have the advantages of being green, efficient and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 NCQDs@Ti3C2T prepared in Example 1 x TEM image of composite lubricating material (25nm);

[0020] Figure 2 NCQDs@Ti3C2T prepared in Example 1 x TEM image of composite lubricating material (10nm);

[0021] Figure 3 NCQDs@Ti3C2T prepared in Example 1 x XRD pattern of composite lubricating material;

[0022] Figure 4 NCQDs@Ti3C2T prepared in Example 1 x Friction coefficient curve of composite lubricating material in sunflower oil;

[0023] Figure 5 NCQDs@Ti3C2T prepared in Example 1 x Friction coefficient curve of composite lubricating material in PAO10. DETAILED DESCRIPTION

[0024] The specific contents of the present invention are further explained in detail below in conjunction with embodiments.

[0025] Embodiment 1:

[0026] Step 1: Dissolve 4 g urea and 12 g sodium hydroxide in 40 mL acetaldehyde, mix and stir for 2 hours, then ultrasonicate for 1 hour, wash by centrifugation with distilled water 6 times to obtain NCQDs, and disperse the NCQDs in 20 mL water to obtain NCQDs dispersion;

[0027] Step 2: 2 g of Ti3AlC2 powder was slowly added to 20 mL of hydrofluoric acid while stirring. After stirring, the resulting suspension was isothermally stirred at 25 ° C for 48 hours. The resulting product was centrifuged and washed with distilled water until the supernatant was neutral. After vacuum drying at 60 ° C for 12 hours, Ti3C2T x Material;

[0028] Step 3: 0.25 g of Ti3C2T prepared in step 2 x The powder was added to the NCQDs dispersion and stirred for 12 hours. The product was allowed to settle for 5 hours. The unassembled NCQDs were removed by centrifugation and freeze-dried for 48 hours to obtain NCQDs@Ti3C2T x powder.

[0029] Figure 1 NCQDs@Ti3C2T prepared in Example 1 x TEM image of composite lubricating material (25nm); Figure 2 NCQDs@Ti3C2T prepared in Example 1 x TEM image of composite lubricating material (10nm); Figure 1 and Figure 2 As shown, functionalized carbon quantum dots NCQDs were successfully assembled on Ti3C2T x Layered nanosheet surface.

[0030] Figure 3 NCQDs@Ti3C2T prepared in Example 1 x XRD pattern of composite lubricating material; Figure 3 As shown, due to the composite of functionalized carbon quantum dots NCQDs, NCQDs@Ti3C2T x With Ti3C2T x Compared with the XRD patterns of Ti3C2T, the (002) peak shows an enhanced left shift, which proves the successful assembly of NCQDs and the introduction of NCQDs further increases the x The inter-layer spacing.

[0031] Figure 4 NCQDs@Ti3C2T prepared in Example 1 x Friction coefficient curve of composite lubricating material in sunflower oil; Figure 4 It can be seen that functionalized carbon quantum dots NCQDs and Ti3C2T x The composite lubricating material significantly reduces the friction coefficient of sunflower oil and has excellent lubrication properties.

[0032] Figure 5 NCQDs@Ti3C2T prepared in Example 1 x The friction coefficient curve of composite lubricating material in PAO10 is given by Figure 5 It can be seen that functionalized carbon quantum dots NCQDs and Ti3C2T x The composite lubricating material effectively reduces the friction coefficient of PAO10 and has excellent lubrication performance.

[0033] Embodiment 2:

[0034] Step 1: Dissolve 4 g urea and 12 g sodium hydroxide in 40 mL acetaldehyde, mix and stir for 1 hour, then ultrasonicate for 1 hour, wash with distilled water by centrifugation 5 times to obtain NCQDs, and disperse the NCQDs in 20 mL water to obtain NCQDs dispersion;

[0035] Step 2: 2 g of Ti3AlC2 powder was slowly added to 20 mL of hydrofluoric acid while stirring. After stirring, the resulting suspension was isothermally stirred at 25 ° C for 72 hours. The resulting product was centrifuged and washed with distilled water until the supernatant was neutral. After vacuum drying at 60 ° C for 12 hours, Ti3C2T x Material;

[0036] Step 3: 0.20 g of Ti3C2T prepared in step 2 x The powder was added to the NCQDs dispersion and stirred for 10 hours. The product was allowed to settle for 5 hours. The unassembled NCQDs were removed by centrifugation and freeze-dried for 48 hours to obtain NCQDs@Ti3C2T x powder.

[0037] Embodiment 3:

[0038] Step 1: Dissolve 4 g urea and 12 g sodium hydroxide in 40 mL acetaldehyde, mix and stir for 2 hours, then ultrasonicate for 1.5 hours, wash with distilled water by centrifugation for 5 minutes to obtain NCQDs, and disperse the NCQDs in 20 mL water to obtain NCQDs dispersion;

[0039] Step 2: 2 g of Ti3AlC2 powder was slowly added to 20 mL of hydrofluoric acid while stirring. After stirring, the resulting suspension was isothermally stirred at 25 ° C for 60 hours. The resulting product was centrifuged and washed with distilled water until the supernatant was neutral. After vacuum drying at 60 ° C for 12 hours, Ti3C2T x Material;

[0040] Step 3: 0.15 g of Ti3C2T prepared in step 2 x The powder was added to the NCQDs dispersion and stirred for 18 hours. The product was allowed to settle for 8 hours. The unassembled NCQDs were removed by centrifugation and freeze-dried for 48 hours to obtain NCQDs@Ti3C2T x powder.

[0041] Embodiment 4:

[0042] Step 1: Dissolve 4 g urea and 12 g sodium hydroxide in 40 mL acetaldehyde, mix and stir for 2 hours, then ultrasonicate for 1 hour, wash 8 times by centrifugation with distilled water to obtain NCQDs, and disperse NCQDs in 20 mL water to obtain NCQDs dispersion;

[0043] Step 2: 2 g of Ti3AlC2 powder was slowly added to 20 mL of hydrofluoric acid while stirring. After stirring, the resulting suspension was isothermally stirred at 25 ° C for 48 hours. The resulting product was centrifuged and washed with distilled water until the supernatant was neutral. After vacuum drying at 60 ° C for 12 hours, Ti3C2T x Material;

[0044] Step 3: 0.25 g of Ti3C2T prepared in step 2 x The powder was added to the NCQDs dispersion and stirred for 24 hours. The product was allowed to settle for 10 hours. The unassembled NCQDs were removed by centrifugation and freeze-dried for 48 hours to obtain NCQDs@Ti3C2T x powder.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the present invention.

Claims

1. A method for preparing a functionalized carbon quantum dot and MXene composite lubricating material, characterized in that: The following steps are involved: Step 1: Dissolve urea and sodium hydroxide in acetaldehyde in a mass ratio of 1:3:10, mix and stir for 1 to 2 hours, ultrasonically treat for 1 hour, centrifuge and wash to obtain NCQDs, and disperse the NCQDs in water to obtain a NCQDs dispersion with a mass concentration of 0.11 g / ml; Step 2: Ti3AlC2 powder is slowly added to hydrofluoric acid at a mass ratio of 1:10 while stirring, and the resulting suspension is isothermally stirred for 48 to 72 hours. The resulting product is centrifugally washed and vacuum dried to obtain Ti3C2T x powder; Step 3: Prepare NCQDs and Ti3C2T x The mass ratio of Ti3C2T prepared in step 2 is 2.2: (0.15-0.25). x The powder was added to the NCQDs dispersion, stirred for 10 to 24 hours, and allowed to stand for 5 to 10 hours. The obtained product was centrifuged and freeze-dried to obtain NCQDs@Ti3C2T x powder.

2. The method for preparing the functionalized carbon quantum dots and MXene composite lubricating material according to claim 1, characterized in that: The centrifugal washing described in step 1 is centrifugal washing with distilled water for 5 to 8 times.

3. The method for preparing the functionalized carbon quantum dots and MXene composite lubricating material according to claim 1, characterized in that: The centrifugal washing in step 2 is centrifugal washing with distilled water until the supernatant is neutral.

4. The method for preparing the functionalized carbon quantum dots and MXene composite lubricating material according to claim 1, characterized in that: The temperature of the isothermal stirring in step 2 is 25°C.

5. The method for preparing the functionalized carbon quantum dots and MXene composite lubricating material according to claim 1, characterized in that: The vacuum drying described in step 2 is vacuum drying at 60° C. for 12 hours.

6. A functionalized carbon quantum dot and MXene composite lubricating material prepared by the method according to any one of claims 1 to 5.

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