阅读说明：本技术 一种高稳定性的二维黑磷烯及制备方法和用途 (High-stability two-dimensional black phosphorus alkene, and preparation method and application thereof ) 是由 许晖 周望 李启笛 杨金曼 周固礼 李华明 于 2019-09-17 设计创作，主要内容包括：本发明为一种高稳定性的二维黑磷烯及制备方法和用途,涉及一种超声液相剥离,利用富含羟基官能团的有机溶剂做来源,引入羟基的二维超薄黑磷制备方法,属于二维材料的制备方法技术领域。本发明对材料本身改性,利用有机溶剂,在黑磷表面引入羟基官能团,使其在空气中也能稳定存在。目前,利用有机溶剂引入有机官能团改性超薄黑磷表面,将块状黑磷剥离至不超过2nm的,且能增加稳定性和催化活性。(The invention discloses a high-stability two-dimensional black phosphorus alkene, a preparation method and application thereof, relates to an ultrasonic liquid phase stripping two-dimensional ultrathin black phosphorus preparation method by introducing hydroxyl groups by using an organic solvent rich in hydroxyl functional groups as a source, and belongs to the technical field of preparation methods of two-dimensional materials. The invention modifies the material itself, introduces hydroxyl functional group on the black phosphorus surface by using organic solvent, and makes the black phosphorus exist stably in the air. At present, organic functional groups are introduced by using an organic solvent to modify the surface of the ultrathin black phosphorus, so that the massive black phosphorus is stripped to be not more than 2nm, and the stability and the catalytic activity can be improved.)

1. The two-dimensional black phosphorus alkene is characterized by having an ultrathin thickness not more than 2nm, being stable and not easy to be oxidized in air, and being capable of being used for photocatalytic reduction of CO₂The catalyst of (1).

2. The preparation method of high-stability two-dimensional black phosphorus alkene as claimed in claim 1, characterized by comprising the following steps:

(1) weighing tin powder, iodine and red phosphorus, mixing and putting the tin powder, the iodine and the red phosphorus into a quartz ampule, then sealing the quartz ampule under the protection of nitrogen, putting the quartz ampule into a muffle furnace, and reacting for a certain time at a certain temperature to obtain bulk phase black phosphorus;

(2) freezing the bulk phase black phosphorus in liquid nitrogen for a certain time, then dispersing the frozen solid in an organic solvent, and introducing hydroxyl on the surface of the solid to protect excessive contact air or water on the surface of the solid;

(3) treating the dispersion liquid in an ultrasonic reactor for a certain time, carrying out water bath, and carrying out centrifugal separation on the dispersion liquid to obtain a supernatant containing two-dimensional ultrathin black phosphorus;

(4) and (3) freeze-drying the supernatant to obtain the two-dimensional ultrathin black phosphorus powder.

3. The preparation method according to claim 2, wherein in the step (1), the mass ratio of tin powder, red phosphorus and iodine is 10: 5: 1; the length of the quartz ampule is 100mm, the inner diameter is 8mm, and the wall thickness is 1 mm; the muffle furnace is heated to 600 ℃ from room temperature within 7h, and then the reaction is carried out for 5-10h at 600 ℃.

4. The method according to claim 2, wherein in the step (2), the mass of the bulk black phosphorus is 50-150 mg; freezing for 30-60 min; the organic solvent is Isopropanol (IPA), ethanol (EtOH) or methanol (CH3 OH); the organic solvent is diluted by water, the volume ratio of the organic solvent to the water is 1:0.5-1, and the dosage of the organic solvent is 30-50 mL.

5. The method of claim 2, wherein the method comprises: in the step (3), the ultrasonic reaction time is 3-5 h; power 100-; the water bath temperature is 0-10 ℃; the rotation speed of the centrifugal separation is 500-.

6. The method according to claim 2, wherein the temperature of the freeze-drying in the step (4) is 60 to 80 ℃ below zero.

Technical Field

The invention relates to ultrasonic liquid phase stripping, in particular to a preparation method of two-dimensional ultrathin black phosphorus by introducing hydroxyl groups by taking an organic solvent rich in hydroxyl functional groups as a source, belonging to the technical field of preparation methods of two-dimensional materials.

Background

In recent years, two-dimensional ultrathin nano materials are used for photocatalysis of CO₂Research on the application of reduction is increasing. The two-dimensional ultrathin material has ultrathin thickness and overlarge specific surface area, so that a large number of surface coordination unsaturated atoms can be provided as catalytic active sites for improving catalytic activity. Compared with the bulk material, the special two-dimensional structure endows the ultrathin material with good grain boundary connectivity, so that the ultrathin material is in close contact with reactants, interface charge is promoted to be rapidly transferred, electrochemical reaction is accelerated, corrosion rate is slowed down, and the like. Meanwhile, the two-dimensional ultrathin material can easily realize the regulation and control of an atomic structure and an electronic structure, and the properties and functions of the material can be more easily regulated by utilizing methods such as surface modification or functionalization, element doping, defect engineering and the like, so that the optimization of the catalytic performance of the two-dimensional ultrathin material is facilitated, and conditions are created for establishing the relationship between the microstructures and the catalytic performance of the microstructures from an atomic scale.

Black phosphorus, as a semiconductor, has a direct bandgap structure and a high electron mobility. The band gap change from bulk phase to single layer is 0.3-2.0eV, which can compensate the graphene (A), (B), (C<0.2eV) and transition metal chalcogenide (1.5-2.0eV), and the band gap of the black phosphorus can be adjusted according to the layer number of the black phosphorus nanosheets, so that the black phosphorus has a wide light absorption range from visible light to near infrared, and the characteristics promote the application of the two-dimensional material in the field of photocatalysis. Meanwhile, the high carrier mobility of the black phosphorus reaches 1000cm²V^-1. Usually, black phosphorus nanosheets with high quality and few layers can be prepared by liquid phase stripping, and related work (CN109433232A) is carried out at the early stage, so that the blocky black phosphorus can be stripped to 5-6 nanometers, but the black phosphorus obtained by stripping is easily oxidized in water and air.

At present, the discussion of the stability problem of black phosphorus is still in the starting stage, and no effective solution is available. Most researchers still adopt an anaerobic environment when taking a stripping sample, so that the material is stable and is not interfered by the outside; the invention modifies the material itself, introduces hydroxyl functional group on the black phosphorus surface by using organic solvent, and makes the black phosphorus exist stably in the air. At present, organic functional groups are introduced by using an organic solvent to modify the surface of the ultrathin black phosphorus, the massive black phosphorus is stripped to be not more than 2nm, the stability and the catalytic activity can be improved, and no relevant article reports exist.

Disclosure of Invention

The invention aims to provide a two-dimensional ultra-thin black phosphorus ultrasonic liquid phase stripping method which is good in stability, environment-friendly, simple in process, suitable for industrial production and environment-friendly, and aims at overcoming the defects of the prior art. The two-dimensional ultrathin black phosphorus prepared by the invention has ultrathin thickness not more than 2nm and larger size, and simultaneously has better photocatalysis CO₂Reducing power and stability.

In order to realize the purpose of the invention, the following technical scheme is mainly adopted:

a preparation method of a two-dimensional photocatalytic material comprises the following steps:

(1) weighing tin powder, iodine and red phosphorus, mixing and putting the tin powder, the iodine and the red phosphorus into a quartz ampule, then sealing the quartz ampule under the protection of nitrogen, putting the quartz ampule into a muffle furnace, and reacting for a certain time at a certain temperature to obtain bulk phase black phosphorus;

(2) freezing the bulk phase black phosphorus in liquid nitrogen for a certain time, and then dispersing the frozen solid in an organic solvent;

(3) treating the dispersion liquid in an ultrasonic reactor for a certain time, carrying out water bath, and carrying out centrifugal separation on the dispersion liquid to obtain a supernatant containing two-dimensional ultrathin black phosphorus;

(4) and (3) freeze-drying the supernatant to obtain the two-dimensional ultrathin black phosphorus powder.

The preparation method comprises the following steps: in the step (1), the mass ratio of the tin powder, the red phosphorus and the iodine is 10: 5: 1; the length of the quartz ampule is 100mm, the inner diameter is 8mm, and the wall thickness is 1 mm; the muffle furnace is heated to 600 ℃ from room temperature within 7h, and then the reaction is carried out for 5-10h at 600 ℃.

The preparation method comprises the following steps: in the step (2), the mass of the bulk phase black phosphorus is 50-150 mg; freezing for 30-60 min; the organic solvent is Isopropanol (IPA), ethanol (EtOH) or methanol (CH)₃OH); organic solventThe organic solvent is an organic solvent diluted by water, the volume ratio of the organic solvent to the water is 1:0.5-1, and the dosage of the organic solvent is 30-50 mL.

The preparation method comprises the following steps: in the step (3), the ultrasonic reaction time is 3-5 h; power 100-; the water bath temperature is 0-10 ℃; the rotation speed of the centrifugal separation is 500-.

The preparation method comprises the following steps: in the step (4), the temperature of freeze drying is 60-80 ℃ below zero.

The method of the invention prepares the high-stability two-dimensional ultrathin black phosphorus material.

The invention has the beneficial effects that:

the method adopts an ultrasonic liquid phase treatment method, has the characteristics of mild treatment conditions, simple process, low energy consumption and environmental friendliness, and can easily break bonds among solvent molecules by means of high energy of ultrasonic while performing ultrasonic treatment, overcome the energy barrier of functional groups introduced on the surface, and help the stability of the black phosphorus alkene material, so that the material has the advantages of mass production and stability, and has a certain application prospect.

The two-dimensional ultrathin black phosphorus material prepared by the invention uses an organic solvent for liquid phase stripping, and uses an IPA solvent as an example of a hydroxyl source, the black phosphorus surface obtained by stripping contains a certain amount of hydroxyl, the number of the hydroxyl increases along with the increase of the concentration of the solution, and the probability of the contact of the material and air (mainly oxygen) is reduced because the black phosphorus surface is covered by the hydroxyl. In addition, this time strictly controls the water temperature and the ultrasound time, making the material thinner. The method improves stability of black phosphorus in water and air, and can be used for photocatalysis of CO₂Has a certain application prospect in the reduction aspect.

Drawings

FIG. 1 is an XRD spectrum of black phosphorus before and after ultrasonic liquid phase exfoliation in example 3.

FIG. 2 is an AFM image of two-dimensional ultra-thin black phosphorus prepared in example 3.

FIG. 3 is a Raman spectrum of black phosphorus before and after ultrasonic liquid phase exfoliation in example 3.

FIG. 4 shows bulk black phosphorus and two-dimensional ultra-thin black phosphorus before and after ultrasonic liquid phase exfoliation in example 3CO of₂Reduction activity is compared with the figure.

FIG. 5 is a graph comparing the stability of ultra-thin black phosphorus (M-BP-OH) protected by hydroxyl groups and ultra-thin black phosphorus (M-BP) unprotected by hydroxyl groups in example 3 (exposure to air at room temperature and relative humidity of 90%, (a) and (b) TEM images of M-BP exposure for 0 hour and 24 hours, respectively, (c) AFM images of M-BP exposure for 24 hours, (d) and (e) P2P core XPS spectra of M-BP exposure for 0 day and 10 days, respectively, (f) and (g) TEM images of M-BP-OH exposure for 0 hour and 24 hours, respectively, (h) AFM images of M-BP-OH exposure for 24 hours, and (i) and (j) P2P core XPS spectra of M-BP-OH exposure for 0 day and 10 days, respectively).

Detailed Description

The present invention is illustrated in detail below with reference to specific embodiments using IPA solution as solvent, but not limited thereto

The experimental procedures used in the following examples are conventional unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

Preparation of bulk phase black phosphorus: weighing 1g of tin powder, 0.1g of iodine and 0.5g of red phosphorus, mixing, putting into a quartz ampoule, sealing under the protection of nitrogen, putting the quartz ampoule into a muffle furnace, heating from room temperature to 600 ℃ within 7h, keeping at 600 ℃ for 5-10h, and cooling to obtain bulk phase black phosphorus.