CN109825293B

CN109825293B - Application of titanium carbide nanosheet as up-conversion material

Info

Publication number: CN109825293B
Application number: CN201910093314.3A
Authority: CN
Inventors: 崔小强; 赛世然; 王�锋
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2019-01-30
Filing date: 2019-01-30
Publication date: 2021-04-16
Anticipated expiration: 2039-01-30
Also published as: CN109825293A

Abstract

The invention firstly provides the application of the titanium carbide nanosheet as the up-conversion material, the two-dimensional material with large size is used as the up-conversion material, the material can emit visible light under the excitation of near-infrared light, and the fluorescence luminescence peak position of the material is changed after the wavelength of excitation light is changed. The invention also successfully prepares the MXene nanosheets into fluorescent molecular probes for detecting L-tryptophan.

Description

Application of titanium carbide nanosheet as up-conversion material

Technical Field

The invention belongs to the technical field of up-conversion luminescent materials, and particularly relates to a preparation method of an up-conversion MXene nanosheet capable of exciting visible light by infrared light and a fluorescence property specification.

Background

An upconversion luminescent material is a material that absorbs a plurality of low energy photons and emits high energy photons, i.e. the wavelength of the absorbed light is larger than the wavelength of the emitted light. In the upconversion luminescence phenomenon, the excitation light is usually infrared light or visible light band, and the damage to the biological tissue is greatly reduced compared with ultraviolet light, so the upconversion luminescent material has many applications in biology, for example, it is often applied to cell imaging or biological fluorescent probes.

MXene is a class of two-dimensional materials consisting of transition metal carbides, nitrides or carbonitrides with a thickness of a few atomic layers. As a star material in recent years, MXene has attracted attention worldwide in various fields of energy, optics, catalysis, and the like. The quantum dots of graphene and molybdenum disulfide which are two-dimensional materials have been reported to have the property of up-conversion luminescence, but no up-conversion luminescence property of MXene materials is reported at present. Meanwhile, regarding the mechanism of up-conversion luminescence of quantum dots of a two-dimensional material, it is currently accepted that when the size of the two-dimensional material is small enough, a small size effect is caused, which causes the band structure of the two-dimensional material to change, thereby exhibiting the property of up-conversion luminescence, and based on this theory, up-conversion luminescence of the two-dimensional material is difficult to realize at a relatively large size.

Disclosure of Invention

The object of the present invention is to provide a Ti₃C₂Use of nanoplatelets as upconverting materials.

The object of the present invention is to provide a technique for producing a film having a high qualityThe technical scheme is realized as follows: titanium carbide (Ti)₃C₂) Use of nanoplates as upconverters, the Ti₃C₂The size of the nano sheet is between 100 and 600nm, and the thickness is below 10 nm.

Further, the Ti₃C₂The nano-sheet is obtained by hydrothermal synthesis.

The Ti₃C₂The nano sheet is obtained by hydrothermal synthesis and comprises the following steps:

1) mixing 1.5g of Ti₃AlC₂Added into a mixed solution of 15ml of 6mol/L hydrochloric acid and 1g of LiF, and stirred for 60 hours in a sealed manner at the temperature of 40 ℃.

2) Ti to be etched₃C₂The solution was centrifuged until pH 6 was reached, the supernatant was removed and the pellet was retained.

3) Adding water to the precipitate to dissolve the precipitate. Centrifuging at 3500rpm for 1 hr after ultrasonic treatment to obtain dark green supernatant, and vacuum filtering under the protection of argon gas to obtain Ti₃C₂Nanosheets.

Further, the application is as follows: as a fluorescent molecular probe, the probe can specifically recognize L-tryptophan.

The invention has the beneficial effects that: the invention provides the application of a large-size two-dimensional material as an up-conversion material for the first time, the material can emit visible light under the excitation of near-infrared light, and the fluorescence emission peak position of the material is changed after the wavelength of the excitation light is changed. The invention also successfully prepares the MXene nanosheets into fluorescent molecular probes for detecting L-tryptophan.

Drawings

Fig. 1 is an X-ray diffraction analysis spectrum (XRD) of MXene nanoplatelets prepared in accordance with the present invention and a MAX phase material as a precursor thereof.

Fig. 2 is a Scanning Electron Microscope (SEM) image of aqueous solution of MXene nanoplatelets prepared in accordance with the present invention drop cast onto Anodized Aluminum (AAO) having a pore size of 90 nm.

FIG. 3 is a fluorescence emission spectrum of the MXene nanosheet aqueous solution prepared by the method under the irradiation of infrared rays with the wavelength of 850 nm.

FIG. 4 is a fluorescence emission spectrum of the MXene nanosheet aqueous solution prepared by the method under excitation of light rays with different wavelengths (700 nm-900 nm).

FIG. 5 is a comparison graph of fluorescence intensity before and after adding different kinds of amino acids into MXene nanosheet aqueous solution prepared by the present invention. In these, the solid bars represent intrinsic luminescence intensity, and the open bars represent luminescence intensity after binding with amino acid.

FIG. 6 shows fluorescence emission spectra of MXene in a commercially available aqueous solution after dilution and sonication under 850nm infrared light.

Detailed Description

The technical solution of the invention is further illustrated below with reference to examples, which are not to be construed as limiting the technical solution.

Example 1: the preparation of the MXene nanosheet in this embodiment specifically includes the following steps:

1) 1g LiF and 15ml hydrochloric acid with the concentration of 6mol/L are placed in a Teflon reaction kettle to be mixed, and then the mixture is stirred for 15 minutes at room temperature to enable the two to fully react.

2) Adding 1.5g of Ti into the solution obtained in the step 1) under stirring₃AlC₂And reacting for 60 hours at 40 ℃ under the condition of continuous stirring to etch Al in the raw materials. It is noteworthy that the feeding process is exothermic and needs to be carried out slowly in 10-15 minutes.

3) To obtain a monolayer of MXene sheet, the reacted solution obtained in step 2) was washed several times by centrifugation, the supernatant was decanted after each centrifugation, and the next centrifugation was performed after adding deionized water and shaking for 45 seconds of ultrasound to dissolve MXene adhering to the tube wall. The initial centrifugation speed is 3500r/min, then the centrifugation speed is increased by 500r/min in turn each time, the centrifugation time is 8 minutes until the PH of the supernatant is above 6, the supernatant is decanted, the supernatant is centrifuged for 1 hour at the rotation speed of 3500r/min, the supernatant is taken, nitrogen is introduced, and then the supernatant is stored, and the supernatant is dark green.

4) And (3) carrying out ultrasonic treatment on the supernatant obtained in the step 3) for 30 minutes, carrying out suction filtration under the protection of argon gas to obtain MXene nanosheets of hundreds of nanometer levels, and storing the MXene nanosheets at low temperature.

FIG. 1 shows MXene nanosheets prepared according to the present invention and MAX phase material (Ti) as precursor thereof₃AlC₂) X-ray diffraction analysis pattern (XRD). Ti can be seen from the figure₃AlC₂The characteristic peak of (A) disappears, which indicates that Al element in the MAX phase is etched; the map shows Ti₃C₂Indicating that the reaction successfully produced Ti₃C₂。

Fig. 2 is a Scanning Electron Microscope (SEM) image of an aqueous solution of MXene nanoplatelets prepared according to the present invention dispersed on Anodized Aluminum (AAO) having a pore size of 90 nm. From this image, it can be seen that the monolayer flakes are randomly distributed on the pore structure of AAO, which indicates that MXene prepared by the above method is indeed a sheet-like structure with a size of about 100-600nm and a thickness distribution of 6-10nm as measured by AFM.

Example 2 use of Ti prepared in example 1₃C₂And a nanosheet, and the fluorescence properties of the aqueous solution thereof are measured. The method specifically comprises the following steps: dissolving 1mg of the prepared MXene nanosheet in 10ml of deionized water, and shaking for 2 minutes to completely dissolve the MXene nanosheet to obtain a solution with the concentration of 0.1 mg/ml. The obtained solution was put into a cuvette, and the emission spectra thereof under irradiation with ultraviolet light having a wavelength of 365nm and infrared light having a wavelength of 850nm were measured using a fluorescence spectrometer. FIG. 3 shows fluorescence emission spectrum of MXene nanosheet aqueous solution prepared in the invention under irradiation of infrared light with wavelength of 850 nm. It can be seen from the figure that the aqueous solution has a distinct luminescence peak position at 550nm under the excitation of 850nm infrared light, and the phenomenon shows that the aqueous solution has the property of up-conversion luminescence.

Example 3: the MXene nanosheets in example 1 were used to measure fluorescence emission spectra obtained from aqueous solutions thereof under excitation with light of different wavelengths (700nm to 900 nm). The method specifically comprises the following steps: the wavelength of the excitation light in example 2 is changed to 700nm, and the test process in example 2 is repeated to obtain the fluorescence emission spectrum of the MXene nanosheet aqueous solution under the excitation of 700nm light. Then, the above steps are repeated each time the wavelength of the emitted light is increased by 25nm, and the wavelength of the excitation light reaches 900 nm. FIG. 4 shows fluorescence emission spectra obtained by exciting MXene nanosheet aqueous solution prepared by the invention under light rays with different wavelengths (700 nm-900 nm). It can be seen from the figure that with the continuous normal wavelength of the excitation light, the fluorescence emission peak position of the aqueous solution of MXene nanosheets is red-shifted, and in the process, the wavelength of the emitted light covers almost the whole visible light wavelength range except the purple light.

Example 4: ti prepared in example 1 was used₃C₂The water solution of the nano-sheet is mixed with different amino acids to detect the specific binding condition, and specifically comprises the following steps:

example 2 was repeated to obtain Ti of 0.1mg/ml₃C₂The fluorescence intensity of the aqueous solution of the nano-sheet under the irradiation of infrared light with the wavelength of 850nm is measured again by adding 5mg of amino acid with different types into the solution, shaking the solution lightly by hands, and comparing the fluorescence intensity of the solution at the wavelength of 850nm with the fluorescence intensity of the solution at the previous time and the fluorescence intensity of the solution at the next time. FIG. 5 is a comparison graph of fluorescence intensity before and after adding different kinds of amino acids into MXene nanosheet aqueous solution prepared by the present invention. It can be seen that the fluorescence intensity of the solution did not change much after the addition of amino acids other than L-tryptophan, but the fluorescence intensity of the solution decreased greatly after the addition of tryptophan. Thus, the Ti prepared by the scheme₃C₂The aqueous solution of the nano-sheet can specifically recognize L-tryptophan and can be used as a fluorescent molecular probe of L-tryptophan.

Example 5: using commercially available Ti₃C₂The aqueous solution is used for detecting the fluorescence property of the aqueous solution, and specifically comprises the following components:

ti purchased₃C₂The aqueous solution was manufactured by Jilin scientific Co., Ltd at a concentration of 5 mg/ml. Mixing the obtained Ti₃C₂Diluting the aqueous solution to a concentration of 0.1g/ml, subjecting the aqueous solution to ultrasonic treatment, wherein the size of the aqueous solution after ultrasonic treatment is about 100-600nm, and the thickness distribution of the aqueous solution is 6-10nm as measured by AFM.

Thereafter, example 2 was repeated, and the fluorescence intensity of the aqueous solution under irradiation with infrared light having a wavelength of 850nm was measured. FIG. 6 shows the fluorescence emission spectrum of an aqueous solution under irradiation with infrared light having a wavelength of 850 nm. It can be seen from the figure that the aqueous solution can also show a distinct luminescence peak position at 550nm under the excitation of 850nm infrared light.

The specific binding property of the sample was measured according to the method described in example 4, and the structure showed that the fluorescence intensity of the solution did not change much after the addition of amino acids other than L-tryptophan, but the fluorescence intensity of the solution decreased greatly after the addition of tryptophan.

Claims

1. Ti₃C₂Use of nanoplates as upconverters, the Ti₃C₂The size of the nano sheet is between 100 and 600nm, and the thickness is below 10 nm; the Ti₃C₂The nano-sheet is obtained by hydrothermal synthesis; the hydrothermal synthesis method comprises the following steps:

1) mixing 1.5g of Ti₃AlC₂Adding the mixture into 15ml of mixed solution of 6mol/L hydrochloric acid and 1g of LiF, and hermetically stirring the mixture for 60 hours at the temperature of 40 ℃;

2) ti obtained after the treatment of the step 1)₃C₂Centrifuging and washing the solution until the pH is about =6, removing the supernatant, and keeping the precipitate;

3) adding water into the precipitate to dissolve the precipitate; centrifuging at 3500rpm for 1 hr after ultrasonic treatment to obtain dark green supernatant, and vacuum filtering under the protection of argon gas to obtain Ti with size of 100-600nm₃C₂Nanosheets.

2. Use according to claim 1, wherein Ti is added₃C₂The nano-sheet is used as a fluorescent molecular probe.

3. The use according to claim 2, wherein the fluorescent molecular probe specifically recognizes L-tryptophan.