CN110668412A - Method for preparing black phosphorus nanosheet through low-temperature mediation - Google Patents

Abstract

The invention relates to a technology for removing environmental pollutants, in particular to a method for preparing black phosphorus nanosheets mediated by low temperature. The ground black phosphorus powder was immersed in excess liquid nitrogen (temperature of -196°C) for low-temperature freezing treatment for 0.5-6h, and then the treated black phosphorus powder was dispersed in oxygen-free water. The clear liquid is the suspension containing the two-dimensional black phosphorus nanosheets. The method of the invention combines the method of liquid nitrogen low temperature mediated pretreatment and liquid probe ultrasound, collects the supernatant by means of centrifugal separation, can prepare two-dimensional black phosphorus nanosheets with high efficiency and low cost, and removes environmental pollution. The effect is remarkable.

Description

A low-temperature-mediated method for preparing black phosphorus nanosheets

technical field

The invention relates to a technology for removing environmental pollutants, in particular to a method for preparing black phosphorus nanosheets mediated by low temperature.

Background technique

Black phosphorus has attracted worldwide attention since it was successfully stripped in 2014. Two-dimensional black phosphorus has many excellent properties, such as high carrier mobility and switching ratio, optical/electrical anisotropy, photothermal effect, photodynamic effect, excellent biocompatibility, and large ratio. These characteristics make 2D black phosphorus show great potential application value in field effect transistors, thermoelectric materials, light monitoring devices, sensors and biomedicine.

The development of simple, efficient, and practical methods for the preparation of 2D black phosphorus nanosheets is crucial for studying their properties and applications. At present, the existing preparation methods of two-dimensional black phosphorus are generally divided into two types: top-down and bottom-up methods. The bottom-up method mainly includes chemical vapor deposition and wet chemical synthesis method; the top-down method mainly includes mechanical peeling, liquid phase peeling and ion-wiping layer peeling.

The liquid-phase exfoliation method is a widely used method to prepare ultrathin 2D nanosheets by exfoliation from layered bulk crystalline materials, which can be used to prepare ultrathin 2D nanosheets in solution using low cost, high efficiency and large scale. dimensional black phosphorus nanomaterials, but the low yield is a problem that cannot be ignored. Therefore, improving the yield of liquid phase exfoliation of black phosphorus by improving the method steps is a research direction for the preparation of two-dimensional black phosphorus nanosheets by liquid phase exfoliation.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for preparing black phosphorus nanosheets mediated by low temperature.

In order to achieve the above object, the technical scheme of the present invention is:

A method for preparing black phosphorus nanosheets mediated by low temperature, the black phosphorus powder after grinding is immersed in excess liquid nitrogen (temperature is -196 ℃) for low temperature freezing treatment for 0.5-6h, and then the processed black phosphorus powder is dispersed in a Dispersed in oxygenated water, ultrasonically treated in a water bath after dispersion, and centrifuged to collect the supernatant, which is a suspension containing two-dimensional black phosphorus nanosheets.

The ground black phosphorus powder is immersed in excess liquid nitrogen (temperature is -196° C.) for 3-6 hours for low-temperature freezing treatment.

The black phosphorus after the low-temperature freezing treatment is dissolved in oxygen-free water and ultrasonicated with a water bath probe for 6-18 hours, and the temperature of the water bath is controlled at 0-10°C.

After the water bath is sonicated, centrifuge at a centrifugal speed of 1000 rpm for 20 min, and the collected supernatant is a suspension containing two-dimensional black phosphorus nanosheets.

Principle: The low-temperature pretreatment of black phosphorus powder by adding liquid nitrogen in the present invention can weaken the van der Waals force between the black phosphorus layers. More efficient preparation of two-dimensional black phosphorus nanosheets. At the same time, the pretreatment of adding liquid nitrogen will not introduce other impurities, and will not affect the purity and quality of the exfoliated two-dimensional black phosphorus nanosheets.

The present invention has the following advantages:

1. The present invention adds the process of liquid nitrogen low-temperature pretreatment before the ultrasound of the black phosphorus liquid phase probe, weakens the van der Waals force between the black phosphorus sheets, and makes the process of liquid phase stripping two-dimensional black phosphorus nanosheets more efficient, At the same time, the low-temperature treatment process of adding liquid nitrogen is simple, and other impurities will not be introduced. The liquid phase exfoliation method can be used to ensure the efficient and low-cost preparation of two-dimensional black phosphorus nanosheets.

2. The two-dimensional black phosphorus nanosheets prepared by the present invention have a larger specific surface area, and under anaerobic conditions, the adsorption amounts of dyes (methyl orange as an example) and antibiotics (ciprofloxacin as an example) are all high. Reported at higher levels in the literature, it has potential as an adsorbent for pollutants in the environment.

Description of drawings

FIG. 1 is a schematic diagram of a preparation process provided in an embodiment of the present invention.

FIG. 2 is an intuitive comparison picture of preparing a two-dimensional black phosphorus suspension without adding liquid nitrogen and adding liquid nitrogen low-temperature pretreatment to prepare a two-dimensional black phosphorus suspension according to an embodiment of the present invention.

3A and B are the adsorption isotherms of the two-dimensional black phosphorus nanosheets provided in the embodiment of the present invention to methyl orange and ciprofloxacin, wherein the solid line, the short dashed line and the long dashed line are the Langmuir adsorption isotherms made respectively , Freundlich, and Dubinin-Ashtaklov fits.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments.

Example 1

Preparation method of two-dimensional black phosphorus nanosheets as shown in Figure 1

1) Grind the bulk black phosphorus into powder in a mortar, immerse the black phosphorus powder in liquid nitrogen for 3 hours (temperature is -196°C), and then weigh 50 mg of the black phosphorus powder treated with liquid nitrogen in 40 mL of brown into the vial, and then add 30 mL of deoxygenated water to the brown vial to form a black phosphorus powder dispersion.

2) Passing the obtained black phosphorus powder dispersion through an ice pack water bath, ultrasonicating the probe for 6 hours, and controlling the temperature below 10°C. After ultrasonication, the supernatant was obtained by centrifugation (rotation speed was 1000 rpm, centrifugation time was 20 min) to obtain the target suspension containing two-dimensional black phosphorus nanosheets with a concentration of 235.8 ± 12.2 mg/L (see Figure 2).

The oxygen-free water needs to be dissolved in _N2 and then treated with a water bath probe.

Comparative ratio

Preparation method of two-dimensional black phosphorus nanosheets

(1) Grind the massive black phosphorus into powder in a mortar, then weigh 50 m of the black phosphorus powder ground into powder into a 40 mL brown vial, and then add 30 mL of deoxygenated water to the brown vial to form black phosphorus powder dispersion liquid.

(2) The obtained black phosphorus powder dispersion is passed through an ice pack water bath, and the probe is sonicated for 6 hours, and the temperature is controlled below 10°C. After ultrasonication, the supernatant was obtained by centrifugation (rotation speed was 1000 rpm, centrifugation time was 20 min), and the target two-dimensional black phosphorus nanosheets were obtained, and the concentration was about 79.6±8.4 mg/L (see Figure 2).

As can be seen from Figure 2, in the process of preparing black phosphorus nanosheets by liquid phase ultrasound, adding liquid nitrogen at the same time for low-temperature mediation is beneficial to obtain high-concentration two-dimensional black phosphorus nanosheets, and it can be seen that the method of the present invention is adopted. The preparation of two-dimensional black phosphorus nanosheets of the same quality can not only reduce the time cost, but also reduce the energy consumption of the preparation process. At the same time, the pretreatment of adding liquid nitrogen will not introduce other impurities, and will not affect the purity and quality of the exfoliated two-dimensional black phosphorus nanosheets.

Application example 1

Adsorption experiments for removing dyes (methyl orange) in water using the two-dimensional black phosphorus nanosheets obtained in the above examples:

(1) Prepare methyl orange solutions with different concentration ranges; wherein, the different concentrations are 0, 5, 10, 15, 20, 30, 40, 60, 70, 80, 90, 150, 200, 250, 450, 500 mg respectively /L;

(2) Mix 8 mL of methyl orange solution with different concentrations and 2 mL of black phosphorus suspension of known concentration prepared in the above-mentioned example, mix them in a 10 mL glass vial, seal with a lid with a Teflon gasket, put Shake in a constant temperature shaking box (25±1°C, 150rpm) for 48h to reach adsorption equilibrium.

(3) After the above adsorption equilibrium, the sample was centrifuged at 10,000 rpm for 30 min to achieve the purpose of solid-liquid separation. Finally, a certain amount of supernatant was pipetted and the concentration of methyl orange remaining in the solution was determined by UV-Vis.

It can be seen from Figure 3A that the two-dimensional black phosphorus has a good adsorption and removal effect on the ionic dye methyl orange.

Application example 2

Adsorption experiments for removing antibiotics (ciprofloxacin) in water using the two-dimensional black phosphorus nanosheets obtained in the above examples:

(4) Prepare ciprofloxacin solutions with different concentration ranges; wherein, the different concentrations are 0, 0.15, 0.50, 3.5, 7.0, 9.0, 13.0, 22.0, 26.0, 30.0, 35.0 mg/L;

(5) Take 8 mL of ciprofloxacin solution of different concentrations and mix 2 mL of black phosphorus suspension with known concentration obtained in the above-mentioned example in a 10 mL glass vial, seal it with a lid with a Teflon gasket, and place it on the Shake in a constant temperature shaking box (25±1°C, 150rpm) for 48h to reach adsorption equilibrium.

(6) After the above adsorption equilibrium, the sample was centrifuged at 10,000 rpm for 30 min to achieve the purpose of solid-liquid separation. Finally, a certain amount of supernatant was pipetted and the remaining ciprofloxacin concentration in the solution was determined by UV-Vis.

It can be seen from Figure 3B that the two-dimensional black phosphorus has a good adsorption and removal effect on ciprofloxacin in antibiotics.

The above-mentioned embodiment is one of the application cases in the preparation of black phosphorus in the patent of the present invention, but does not limit the present invention in any form.

Claims (4)

1. a low-temperature-mediated method for preparing black phosphorus nanosheets, is characterized in that: the black phosphorus powder after grinding is immersed in excess liquid nitrogen (temperature is -196° C.) to carry out low-temperature freezing treatment for 0.5-6, and then the processed The black phosphorus powder was dispersed in oxygen-free water, after the dispersion, the water bath was ultrasonically treated, and the supernatant was collected by centrifugation to obtain a suspension containing two-dimensional black phosphorus nanosheets. 2. The method for preparing black phosphorus nanosheets by low temperature mediation according to claim 1, wherein the black phosphorus powder is immersed in excess liquid nitrogen (temperature is -196°C) for 3-6h after the grinding to carry out low temperature freezing deal with. 3. The method for preparing black phosphorus nanosheets by low-temperature mediation according to claim 1 or 2, is characterized in that: the black phosphorus after the low-temperature freezing treatment is dissolved in oxygen-free water and carries out water bath probe ultrasound 6-18h, and the water bath temperature Control at 0-10 ℃. 4. The method for preparing black phosphorus nanosheets mediated by low temperature according to claim 3, it is characterized in that: after described water bath ultrasonic, with the centrifugal speed of 1000rpm, centrifuge 20min, collect supernatant and is to contain two-dimensional black Suspension of phosphorus nanosheets.

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