CN110668412A

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

Info

Publication number: CN110668412A
Application number: CN201910132540.8A
Authority: CN
Inventors: 赵青; 马微; 张雪娇; 张思玉; 李登宇; 吴丰昌
Original assignee: Institute of Applied Ecology of CAS
Current assignee: Institute of Applied Ecology of CAS
Priority date: 2019-02-22
Filing date: 2019-02-22
Publication date: 2020-01-10
Anticipated expiration: 2039-02-22
Also published as: CN110668412B

Abstract

The invention relates to an environmental pollutant removal technology, in particular to a method for preparing black phosphorus nanosheets through low-temperature mediation. And (2) soaking the ground black phosphorus powder in excessive liquid nitrogen (the temperature is-196 ℃) to carry out low-temperature freezing treatment for 0.5-6h, then dispersing the treated black phosphorus powder in oxygen-free water, carrying out water bath ultrasonic treatment after dispersion, and centrifugally separating and collecting supernatant, namely the suspension containing the two-dimensional black phosphorus nanosheets. The method combines the liquid nitrogen low-temperature mediated pretreatment and liquid probe ultrasonic method, collects the supernatant in a centrifugal separation mode, can prepare the two-dimensional black phosphorus nanosheet with high efficiency and low cost, and has obvious effect of removing environmental pollutants.

Description

Method for preparing black phosphorus nanosheet through low-temperature mediation

Technical Field

The invention relates to an environmental pollutant removal technology, in particular to a method for preparing black phosphorus nanosheets through low-temperature mediation.

Background

Since the successful release of black phosphorus in 2014, it has attracted a great deal of worldwide attention. The two-dimensional black phosphorus has many excellent characteristics, such as high carrier mobility and on-off ratio, optical/electrical anisotropy, photothermal effect, photodynamic effect, excellent biocompatibility, large specific surface area and the like, and the characteristics enable the two-dimensional black phosphorus to show great potential application values in the fields of field effect transistors, thermoelectric materials, optical monitoring devices, sensors, biomedicine and the like.

The method for preparing the two-dimensional black phosphorus nanosheet, which is simple to develop, efficient and feasible, is crucial to the study of the properties and the application of the two-dimensional black phosphorus nanosheet. At present, the existing two-dimensional black phosphorus preparation methods are mainly divided into two types in general terms: top-down and bottom-up approaches. Wherein the bottom-up method mainly comprises chemical vapor deposition and wet chemical synthesis; the top-down method mainly comprises mechanical stripping, liquid phase stripping and ion wipe layer stripping.

The liquid phase stripping method is a widely used method for preparing ultrathin two-dimensional nanosheets by stripping layered bulk crystalline materials, can prepare ultrathin two-dimensional black phosphorus nanomaterials in solution at a low cost, high efficiency and large scale, but has a problem that the yield is low, which is not negligible. Therefore, through the improvement of the method steps, the improvement of the yield of the black phosphorus liquid phase stripping is a research direction for preparing the two-dimensional black phosphorus nanosheet through the liquid phase stripping at present.

Disclosure of Invention

The invention aims to provide a method for preparing black phosphorus nanosheets through low-temperature mediation.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for preparing black phosphorus nanosheets through low-temperature mediation comprises the steps of soaking ground black phosphorus powder in excessive liquid nitrogen (the temperature is-196 ℃) to carry out low-temperature freezing treatment for 0.5-6h, then dispersing the treated black phosphorus powder in oxygen-free water, carrying out water bath ultrasonic treatment after dispersion, carrying out centrifugal separation, and collecting supernate, namely suspension containing two-dimensional black phosphorus nanosheets.

And soaking the ground black phosphorus powder in excessive liquid nitrogen (the temperature is-196 ℃) for 3-6h for low-temperature freezing treatment.

Dissolving the black phosphorus subjected to low-temperature freezing treatment in oxygen-free water, and carrying out water bath probe ultrasonic treatment for 6-18h, wherein the water bath temperature is controlled at 0-10 ℃.

And after the water bath ultrasound treatment, centrifuging for 20min at a centrifugal speed of 1000rpm, and collecting supernatant, namely the suspension containing the two-dimensional black phosphorus nanosheets.

The principle is as follows: according to the invention, liquid nitrogen is added to carry out low-temperature pretreatment on the black phosphorus powder, so that the van der Waals force between black phosphorus layers can be weakened, and the van der Waals force between the black phosphorus layers can be easily destroyed in the subsequent liquid-phase probe ultrasonic treatment, thereby preparing the two-dimensional black phosphorus nanosheet more efficiently. Meanwhile, other impurities cannot be introduced by adding liquid nitrogen for pretreatment, and the purity and the quality of the stripped two-dimensional black phosphorus nanosheet cannot be influenced.

The invention has the following advantages:

1. according to the invention, before the black phosphorus liquid phase probe is subjected to ultrasonic treatment, a liquid nitrogen low-temperature pretreatment process is added, so that the van der Waals force between black phosphorus sheet layers is weakened, the process of liquid phase stripping of the two-dimensional black phosphorus nanosheet is more efficient, and meanwhile, the liquid nitrogen low-temperature treatment process is simple, and other impurities are not introduced. The liquid phase stripping method can be used for ensuring the high-efficiency and low-cost preparation of the two-dimensional black phosphorus nanosheet.

2. The two-dimensional black phosphorus nanosheet prepared by the method has a large specific surface area, the adsorption amounts of dyes (methyl orange for example) and antibiotics (ciprofloxacin for example) are high in reported documents under an anaerobic condition, and the two-dimensional black phosphorus nanosheet has the potential of serving as an adsorbent for pollutants in the environment.

Drawings

Fig. 1 is a schematic view of a preparation process provided in an embodiment of the present invention.

Fig. 2 is an illustrative comparison picture of two-dimensional black phosphorus suspension prepared without adding liquid nitrogen and two-dimensional black phosphorus suspension prepared by adding liquid nitrogen and performing low-temperature pretreatment.

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

Detailed Description

The present invention will be described in further detail with reference to examples.

Example 1

Preparation method of two-dimensional black phosphorus nanosheet shown in figure 1

1) The black phosphorus is ground into powder in a mortar, the black phosphorus powder is soaked in liquid nitrogen for 3h (the temperature is-196 ℃), then 50mg of the black phosphorus powder treated by the liquid nitrogen is weighed into a 40mL brown bottle, and then 30mL of oxygen-free water is added into the brown bottle to form the black phosphorus powder dispersion liquid.

2) And performing probe ultrasonic treatment on the obtained black phosphorus powder dispersion liquid for 6 hours in a water bath mode of an ice bag, wherein the temperature is controlled below 10 ℃. And (3) after ultrasonic treatment, obtaining supernatant through centrifugal separation (the rotating speed is 1000rpm, and the centrifugal time is 20min), and obtaining the suspension containing the two-dimensional black phosphorus nanosheet with the concentration of 235.8 +/-12.2 mg/L (see figure 2).

The oxygen-free water needs to be dissolved in N₂After treatment, it was then used for bath probe sonication.

Comparative example

Preparation method of two-dimensional black phosphorus nanosheet

(1) The black phosphorus was pulverized in a mortar, 50m of the pulverized black phosphorus was weighed in a 40mL brown bottle, and 30mL of oxygen-free water was added to the brown bottle to form a dispersion of the black phosphorus powder.

(2) And performing probe ultrasonic treatment on the obtained black phosphorus powder dispersion liquid for 6 hours in a water bath mode of an ice bag, wherein the temperature is controlled below 10 ℃. And (3) after ultrasonic treatment, obtaining supernatant through centrifugal separation (the rotating speed is 1000rpm, and the centrifugal time is 20min), and obtaining the target two-dimensional black phosphorus-containing nanosheet with the concentration of about 79.6 +/-8.4 mg/L (see figure 2).

As can be seen from fig. 2, in the process of preparing the black phosphorus nanosheet by liquid-phase ultrasound, liquid nitrogen is added within the same time for low-temperature mediation, which is beneficial to obtaining the high-concentration two-dimensional black phosphorus nanosheet, and further, the method for preparing the two-dimensional black phosphorus nanosheet with the same quality can reduce the time cost and the energy consumption in the preparation process. Meanwhile, other impurities cannot be introduced by adding liquid nitrogen for pretreatment, and the purity and the quality of the stripped two-dimensional black phosphorus nanosheet cannot be influenced.

Application example 1

The two-dimensional black phosphorus nanosheet obtained in the above example was used in an adsorption experiment for removing a dye (methyl orange) in a water body:

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

(2) 8mL of methyl orange solution with different concentrations and 2mL of black phosphorus suspension with known concentration prepared in the above example were mixed in a 10mL glass vial, sealed with a cover with a Teflon gasket, and then placed in a constant temperature shaking box (25. + -. 1 ℃, 150rpm) to shake for 48h to reach adsorption equilibrium.

(3) After the adsorption balance, the sample is centrifuged for 30min at 10000rpm, so as to achieve the purpose of solid-liquid separation. Finally, a certain amount of supernatant was removed and the remaining methyl orange concentration in the solution was determined by UV-Vis.

As shown in FIG. 3A, the two-dimensional black phosphorus has a good adsorption removal effect on the ionic dye methyl orange.

Application example 2

The two-dimensional black phosphorus nanosheet obtained in the above example was used in an adsorption experiment for removing antibiotics (ciprofloxacin) in a water body:

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

(5) 8mL of ciprofloxacin solutions with different concentrations were mixed with 2mL of black phosphorus suspension with known concentration obtained in the above example in a 10mL glass vial, sealed with a cover with a Teflon gasket, and then placed in a constant temperature shaking box (25. + -. 1 ℃ C., 150rpm) to shake for 48h to reach adsorption equilibrium.

(6) After the adsorption balance, the sample is centrifuged for 30min at 10000rpm, so as to achieve the purpose of solid-liquid separation. Finally, a certain amount of supernatant was removed and the concentration of ciprofloxacin remaining in the solution was determined by UV-Vis.

As can be seen from fig. 3B, the two-dimensional black phosphorus has a good adsorption removal effect on ciprofloxacin among antibiotics.

The above-mentioned examples are one of the applications of the present invention in preparing black phosphorus, but not intended to limit the present invention in any way.

Claims

1. A method for preparing black phosphorus nanosheets through low-temperature mediation is characterized by comprising the following steps: and (2) soaking the ground black phosphorus powder in excessive liquid nitrogen (the temperature is-196 ℃) to carry out low-temperature freezing treatment for 0.5-6, then dispersing the treated black phosphorus powder in oxygen-free water, carrying out water bath ultrasonic treatment after dispersion, and centrifugally separating and collecting supernatant to obtain the suspension containing the two-dimensional black phosphorus nanosheets.

2. A low temperature mediated process for the preparation of black phosphorus nanoplates as described in claim 1 wherein: and soaking the ground black phosphorus powder in excessive liquid nitrogen (the temperature is-196 ℃) for 3-6h for low-temperature freezing treatment.

3. A low temperature mediated process for the preparation of black phosphorus nanoplates as described in claims 1 or 2 wherein: dissolving the black phosphorus subjected to low-temperature freezing treatment in oxygen-free water, and carrying out water bath probe ultrasonic treatment for 6-18h, wherein the water bath temperature is controlled at 0-10 ℃.

4. A low temperature mediated process for the preparation of black phosphorus nanoplates as described in claim 3 wherein: and after the water bath ultrasound treatment, centrifuging for 20min at a centrifugal speed of 1000rpm, and collecting supernatant, namely the suspension containing the two-dimensional black phosphorus nanosheets.