CN113943576B - Purple phosphorus quantum dot and preparation method and application thereof - Google Patents

Abstract

The invention discloses a purple phosphorus quantum dot and a preparation method and application thereof, firstly, bulk purple phosphorus crystals are ground into powder and then dispersed into an organic solvent for water bath ultrasonic treatment for 2-4 h, and then the powder is taken outPouring the dispersion into a reaction kettle with a polytetrafluoroethylene lining, carrying out solvothermal reaction for 12-24 h at 150-210 ℃, cooling the obtained reaction liquid to room temperature after the reaction is finished, centrifuging for 10-30 min at the rotating speed of 8000-10000 rpm/min, and collecting supernatant to obtain the purple phosphorus quantum dots with fluorescence property. The method has the advantages of simple process, easy operation, environmental protection, high yield and realization of large-scale production. The obtained purple phosphorus quantum dot has controllable size, can be used as a label-free fluorescent probe, and can detect Cu with high selectivity and sensitivity ²⁺ 。

Description

Purple phosphorus quantum dot and preparation method and application thereof

Technical Field

The invention belongs to the technical field of nano materials, and particularly relates to a purple phosphorus quantum dot and a preparation method and application thereof.

Background

Purple phosphorus is a novel two-dimensional material, an allotrope of phosphorus that is more stable than black phosphorus. Importantly, the purple phosphorus has a tunable band gap depending on layers, so that the stable purple phosphorus is expected to show wide application prospects in the fields of field effect transistors, energy storage batteries, biomedicine, sensors and the like based on bridging of the band gaps of the graphene and the transition metal chalcogenide, and is considered to be a novel two-dimensional material with great potential application in the fields of optics and semiconductors.

Although the purple phosphorus alkene is successfully obtained by a mechanical stripping method and a liquid phase stripping method recently, in practical application, the defects of narrow band gap, small reaction active area and the like exist in the large purple phosphorus, and further research and development of the purple phosphorus alkene are restricted. At present, except for a two-dimensional structure, the zero-dimensional quantum dot is a nano material in another form, and the small size endows the zero-dimensional quantum dot with excellent quantum confinement effect and edge effect, so that the zero-dimensional quantum dot can generate stronger fluorescence, and is expected to replace the traditional fluorescent dye and quantum dot to be applied to the fields of fluorescence sensing, photoelectric materials, biomarkers and the like in the future. So far, no method for preparing the purple phosphorus quantum dots is reported, and the further application of the purple phosphorus quantum dots is limited. Therefore, a method for preparing small-sized purple phosphorus quantum dots on a large scale is urgently needed to widen the application of the purple phosphorus quantum dots.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the purple phosphorus quantum dot and the preparation method and application thereof, so as to fill the blank of the preparation method of the purple phosphorus quantum dot at present and further promote the application of the purple phosphorus quantum dot.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

the invention discloses a preparation method of purple phosphorus quantum dots, which is characterized by comprising the following steps:

step 1): grinding the purple phosphorus crystal into powder, and then dispersing the powder into an organic solvent to obtain a dispersion liquid;

step 2): and carrying out water bath ultrasound on the obtained dispersion liquid, carrying out solvothermal reaction on the dispersion liquid subjected to ultrasound, cooling the reaction liquid to room temperature after the reaction is finished, and centrifuging and collecting supernatant to obtain the purple phosphorus quantum dots.

Further, in the step 1), the dosage ratio of the purple phosphorus crystal to the organic solvent is (10-50) mg: (20-100) mL.

Further, in the step 1), the organic solvent is one or more of N-methyl pyrrolidone, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, isopropanol and absolute ethyl alcohol.

Further, in the step 2), the ultrasonic power of the water bath is 200W-600W, the ultrasonic time is 2-4 h, and preferably, the ultrasonic power of the water bath is 450-500W.

Further, in the step 2), the temperature of the solvothermal reaction is 150-210 ℃, and the time of the solvothermal reaction is 12-24 h.

Further, in the step 2), the rotating speed of the centrifugation is 8000-10000 rpm/min, and the centrifugation time is 10-30 min.

The invention also discloses the purple phosphorus quantum dot obtained based on the preparation method, the size of the purple phosphorus quantum dot is controllable, the size of the purple phosphorus quantum dot is 3.16-13.39 nm, and the thickness of the purple phosphorus quantum dot is 1.81-2.31 nm;

furthermore, the purple phosphorus quantum dots have obvious lattice stripes, the lattice spacing is 0.47nm, and the surface of the purple phosphorus quantum dots contains P-O, P = O groups.

Further, the purple phosphorus quantum dot shows obvious absorption characteristics in the area of 300-1000nm, and the maximum excitation wavelength and the maximum emission wavelength of the purple phosphorus quantum dot are 430nm and 522nm respectively.

The fluorescence of the purple phosphorus quantum dots has excitation dependency, and the emission wavelength is red-shifted along with the increase of the excitation wavelength; the lifetime of the purple phosphorus quantum dots is 9.66ns.

The invention also discloses the application of the purple phosphorus quantum dots as a fluorescent probe in Cu detection ²⁺ The use of (1).

Compared with the prior art, the invention has the following beneficial effects:

the invention adopts an ultrasonic-assisted solvothermal method, and can successfully prepare the purple phosphorus quantum dots. The method has the advantages of simple process, easy operation, environmental protection, high yield and realization of large-scale production. Meanwhile, no literature or patent reports about a method for preparing the purple phosphorus quantum dot at present. Therefore, the preparation method of the invention fills the gap.

Further, the mass volume ratio of the purple phosphorus crystal to the organic solvent is 10-50 mg: 20-100 mL, the yield of the prepared purple phosphorus quantum dots is high, the solute can fully react, and the purple phosphorus quantum dots can be uniformly dispersed in the solution.

Furthermore, the water bath ultrasonic power is 450W-500W, the ultrasonic time is 2-4 h, and the purple phosphorus crystal can be uniformly dispersed in the organic solvent, so that the purple phosphorus quantum dots with uniform size can be further prepared.

Furthermore, by controlling the solvothermal time and the solvothermal temperature, purple phosphorus quantum dots with different sizes and thicknesses can be obtained.

The purple phosphorus quantum dot prepared by the invention has excellent fluorescence property, the emission wavelength can be adjusted along with the excitation wavelength, and the purple phosphorus quantum dot can be used as a fluorescent probe for detecting Cu ²⁺ 。

Drawings

FIG. 1 is a high-resolution transmission electron microscope image of purple phosphorus quantum dots prepared in example 1 of the present invention;

FIG. 2 is an infrared spectrum of purple phosphorus quantum dots prepared in example 1 of the present invention;

FIG. 3 is a diagram of the UV-VIS absorption spectrum of purple phosphorus quantum dots prepared in example 1 of the present invention;

FIG. 4 is a fluorescence excitation and fluorescence emission spectrum of the purple phosphorus quantum dot prepared in example 1;

FIG. 5 is a fluorescence emission spectrum of the purple phosphorus quantum dot prepared in example 1 at different excitation wavelengths;

FIG. 6 is a time-resolved fluorescence spectrum of purple phosphorus quantum dots prepared in example 1;

FIG. 7 shows purple phosphorus quantum dots prepared in example 3 with Cu ²⁺ Fluorescence spectra of concentration changes;

FIG. 8 shows the fluorescence quenching degree and Cu of the purple phosphorus quantum dots prepared in example 3 ²⁺ Linear dependence of concentration, wherein (a) is Cu ²⁺ A linear relationship diagram of the concentration within 10-50 mu g/mL, wherein (b) is Cu ²⁺ A linear relationship graph with the concentration of 50-300 mug/mL;

FIG. 9 is a histogram comparing the fluorescence intensity of purple phosphorus quantum dots prepared in example 3 before and after adding different ions with the same concentration;

FIG. 10 is a transmission electron micrograph and a particle size distribution histogram of the purple phosphorus quantum dots obtained in examples 1 to 5, wherein (a), (b), (c), (d), and (e) are transmission electron micrographs of the purple phosphorus quantum dots obtained in examples 1 to 5, respectively, and (f), (g), (h), (i), and (j) are particle size distribution histograms of the purple phosphorus quantum dots obtained in examples 1 to 5, respectively;

FIG. 11 is an atomic force microscope photograph and a height statistical chart of the purple phosphorus quantum dots obtained in examples 1 to 5, wherein (a), (b), (c), (d), and (e) are atomic force microscope photographs of the purple phosphorus quantum dots obtained in examples 1 to 5, respectively, and (f), (g), (h), (i), and (j) are height statistical photographs of the purple phosphorus quantum dots obtained in examples 1 to 5, respectively.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention is described in further detail below with reference to the accompanying drawings:

example 1

(1) Grinding the purple phosphorus crystal into powder by using a mortar, and then taking the purple phosphorus powder to disperse into N-methyl pyrrolidone, wherein the dosage ratio of the purple phosphorus to the N-methyl pyrrolidone is 30mg:60mL;

(2) Putting the dispersion liquid into an ultrasonic cleaning machine to carry out water bath ultrasound for 2 hours, wherein the ultrasound power is 500W;

(3) And transferring the dispersion liquid obtained after the ultrasonic treatment into a reaction kettle with a polytetrafluoroethylene lining, and putting the reaction kettle into an oven to perform solvothermal reaction at the reaction temperature of 150 ℃ for 12 hours.

(4) After the reaction is finished, cooling the reaction liquid to room temperature, centrifuging for 20min at the rotating speed of 10000rpm/min, and taking supernatant to obtain the purple phosphorus quantum dots.

The purple phosphorus quantum dots obtained in this example 1 were characterized, and the results are shown in fig. 1 to 6, where fig. 1 is a high-resolution transmission electron microscope image of the purple phosphorus quantum dots; FIG. 2 is an infrared spectrum of purple phosphorus quantum dots; FIG. 3 is a graph of the UV-VIS absorption spectrum of purple phosphorus quantum dots; FIG. 4 is a fluorescence excitation and fluorescence emission spectra of purple phosphorus quantum dots; FIG. 5 is a fluorescence emission spectrum of purple phosphorus quantum dots at different excitation wavelengths; FIG. 6 is a time-resolved fluorescence spectrum of purple phosphorus quantum dots.

The lattice fringes of the purple phosphorus quantum dots can be clearly seen from fig. 1, in which the lattice spacing of 0.47nm corresponds to the (014) face of the purple phosphorus crystal; from fig. 2, it can be seen that the surface of the purple phosphorus quantum dot contains groups such as P-O, P = O; from fig. 3, it can be seen that the purple phosphorus quantum dots show obvious absorption characteristics in the 300-1000nm region; it can be seen from fig. 4 that the maximum excitation wavelength and the maximum emission wavelength of the prepared purple phosphorus quantum dot are 430nm and 522nm, respectively; from fig. 5, it can be seen that the fluorescence of the purple phosphorus quantum dots has excitation dependence, and as the excitation wavelength increases, the emission wavelength is also red-shifted; the lifetime of the purple phosphorus quantum dot is 9.66ns by ternary fitting of the time-resolved fluorescence spectrum of the purple phosphorus quantum dot in fig. 6.

Example 2

(1) Grinding the purple phosphorus crystal into powder by using a mortar, and then taking the purple phosphorus powder to disperse into N-methyl pyrrolidone, wherein the dosage ratio of the purple phosphorus to the N-methyl pyrrolidone is 10mg:100mL;

(2) Putting the dispersion liquid into an ultrasonic cleaning machine to carry out water bath ultrasound for 3 hours, wherein the ultrasound power is 450W;

(3) And transferring the dispersion liquid obtained after the ultrasonic treatment into a reaction kettle with a polytetrafluoroethylene lining, and putting the reaction kettle into an oven to perform solvothermal reaction at the reaction temperature of 150 ℃ for 18 hours.

(4) After the reaction is finished, cooling the reaction liquid to room temperature, centrifuging for 10min at the rotating speed of 10000rpm/min, and taking supernatant to obtain the purple phosphorus quantum dots.

Example 3

(1) Grinding the purple phosphorus crystal into powder by using a mortar, and then taking the purple phosphorus powder to disperse into N-methyl pyrrolidone, wherein the dosage ratio of the purple phosphorus to the N-methyl pyrrolidone is 20mg:80mL;

(2) Putting the dispersion liquid into an ultrasonic cleaning machine for water bath ultrasonic treatment for 3 hours, wherein the ultrasonic power is 500W;

(3) And transferring the dispersion liquid obtained after the ultrasonic treatment into a reaction kettle with a polytetrafluoroethylene lining, and putting the reaction kettle into an oven to perform solvothermal reaction at the reaction temperature of 150 ℃ for 24 hours.

(4) After the reaction is finished, cooling the reaction liquid to room temperature, centrifuging for 20min at the rotating speed of 8000rpm/min, and taking supernatant to obtain the purple phosphorus quantum dots.

The purple phosphorus quantum dot prepared by the embodiment is used as a fluorescent probe for detecting Cu ²⁺ The use of (1). The purple phosphorus quantum dots prepared in example 3 were first dispersed in N-methylpyrrolidone to make the concentration of the purple phosphorus quantum dot solution 0.1mg/mL, and then 20. Mu.L of Cu of different concentrations were added ²⁺ Is introduced into the above solution. The mixture was shaken and equilibrated for 10min before measuring the fluorescence spectrum using a 430nm laser. As shown in FIG. 7, it can be seen that, within a certain range, cu is accompanied by ²⁺ The fluorescence intensity of the purple phosphorus quantum dots at 520nm is monotonically decreased with the increase of the concentration. Drawing the purple phosphorus quantum dot solution with Cu ²⁺ Concentration increase of fluorescence intensity change curve and fitting it, as shown in FIG. 8, can be found in two intervals of 10-50. Mu.g/mL and 50-300. Mu.g/mL of F/F ₀ And Cu ²⁺ The concentration has good linear relation, and the fitting formulas of different concentration intervals are respectively F/F ₀ ＝0.9922-0.00404[Cu ²⁺ ]And F/F ₀ ＝0.84999-0.0012[Cu ²⁺ ](wherein: F) ₀ For detecting no addition of Cu in the system ²⁺ Corresponding fluorescence intensity value, F is Cu added to the detection system ²⁺ Corresponding fluorescence intensity value), linear correlation coefficient (R) ² ) 0.989 and 0.991, respectively, with a limit of detection of 0.0196 μ M according to the 3-fold standard deviation rule (S/N = 3).

To detect purple phosphorus quantum dot pairs Cu ²⁺ By selecting a series of interfering ions comprising Al ³⁺ ，Ca ²⁺ ，Fe ³⁺ ，K ⁺ ，Mg ²⁺ ，Mn ²⁺ ，Na ⁺ ，Ni ²⁺ ，Co ²⁺ ，Cd ²⁺ ，Zn ²⁺ Substitute for Cu ²⁺ The test was carried out with an interfering ion concentration of 300. Mu.g/mL. After 10min of reaction at room temperature, the fluorescence emission spectra were recorded under the same conditions. As shown in fig. 9, it can be seen that, in addition to Cu ²⁺ Besides causing obvious fluorescence quenching phenomenon, other metal ions have little influence on the fluorescence intensity, so that the purple phosphorus quantum dot of the invention has little influence on Cu ²⁺ Has good selectivity.

Example 4

(1) Grinding the purple phosphorus crystal into powder by using a mortar, and then taking the purple phosphorus powder to disperse into N-methyl pyrrolidone, wherein the dosage ratio of the purple phosphorus to the N-methyl pyrrolidone is 20mg:80mL;

(2) Putting the dispersion liquid into an ultrasonic cleaning machine for water bath ultrasonic treatment for 2h, wherein the ultrasonic power is 500W;

(3) And transferring the dispersion liquid obtained after the ultrasonic treatment into a reaction kettle with a polytetrafluoroethylene lining, and putting the reaction kettle into an oven for solvothermal reaction at the reaction temperature of 180 ℃ for 12 hours.

(4) After the reaction is finished, cooling the reaction liquid to room temperature, centrifuging for 15min at the rotating speed of 8000rpm/min, and taking supernatant to obtain the purple phosphorus quantum dots.

Example 5

(1) Grinding the purple phosphorus crystal into powder by using a mortar, and then taking the purple phosphorus powder to disperse into N-methyl pyrrolidone, wherein the dosage ratio of the purple phosphorus to the N-methyl pyrrolidone is 30mg:90mL;

(2) Putting the dispersion liquid into an ultrasonic cleaner for water bath ultrasonic treatment for 4h, wherein the ultrasonic power is 450W;

(3) And transferring the dispersion liquid obtained after the ultrasonic treatment into a reaction kettle with a polytetrafluoroethylene lining, and putting the reaction kettle into an oven to perform solvothermal reaction at the reaction temperature of 210 ℃ for 12 hours.

(4) After the reaction is finished, cooling the reaction liquid to room temperature, centrifuging for 15min at the rotating speed of 10000rpm/min, and taking supernatant to obtain the purple phosphorus quantum dots.

The purple phosphorus quantum dots obtained in examples 1 to 5 were characterized by using a transmission electron microscope and an atomic force microscope, as shown in fig. 10 to 11, and the results showed that purple phosphorus quantum dots having different sizes and thicknesses could be obtained by controlling the solvothermal time and the solvothermal temperature, the purple phosphorus quantum dots obtained in example 1 had a size of 13.39nm and a thickness of 2.31nm, the purple phosphorus quantum dots obtained in example 2 had a size of 7.40nm and a thickness of 2.28nm, the purple phosphorus quantum dots obtained in example 3 had a size of 3.16nm and a thickness of 1.81nm, the purple phosphorus quantum dots obtained in example 4 had a size of 6.91nm and a thickness of 1.89nm, and the purple phosphorus quantum dots obtained in example 5 had a size of 8.07nm and a thickness of 2.07nm.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims (6)

1. Purple phosphorus quantum dot as fluorescent probe for detecting Cu ²⁺ The application of (1) is characterized in that the preparation method of the purple phosphorus quantum dot comprises the following steps:

step 1): grinding the purple phosphorus crystal into powder, and then dispersing the powder into N-methyl pyrrolidone to obtain a dispersion liquid; the dosage ratio of the purple phosphorus crystal and the N-methyl pyrrolidone is (10-50) mg: (20-100) mL;

step 2): carrying out water bath ultrasound on the obtained dispersion liquid, carrying out solvothermal reaction on the dispersion liquid after the ultrasound, cooling the reaction liquid to room temperature after the reaction is finished, and centrifuging and collecting supernatant to obtain purple phosphorus quantum dots;

the temperature of the solvothermal reaction is 150-210 ℃, and the time of the solvothermal reaction is 12-24 h.

2. The use of claim 1, wherein in the step 2), the ultrasonic power of the water bath is 200-600W, and the ultrasonic time is 2-4 h.

3. The use according to claim 1, wherein in step 2), the rotation speed of the centrifugation is 8000-10000 rpm/min, and the centrifugation time is 10-30 min.

4. The use of claim 1, wherein the ultrasonic power of the water bath is 450-500W.

5. The use of claim 1, wherein the purple phosphorus quantum dots are controllable in size, have a size of 3.16-13.39 nm and a thickness of 1.81-2.31 nm;

the purple phosphorus quantum dots have obvious lattice stripes, the lattice spacing is 0.47nm, and the surfaces of the purple phosphorus quantum dots contain P-O, P = O groups.

6. The use according to claim 1, wherein the purple phosphorus quantum dots exhibit distinct absorption characteristics in the 300-1000nm region, the maximum excitation wavelength and the maximum emission wavelength of the purple phosphorus quantum dots being 430nm and 522nm, respectively;

the fluorescence of the purple phosphorus quantum dots has excitation dependency, and the emission wavelength is red-shifted along with the increase of the excitation wavelength; the lifetime of the purple phosphorus quantum dots is 9.66ns.

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