阅读说明：本技术 一种快速制备BiOBr纳米片的方法 (Method for rapidly preparing BiOBr nanosheet ) 是由 樊启哲 余长林 陈鑫 梁淼 于 2020-05-26 设计创作，主要内容包括：一种快速制备BiOBr纳米片的方法,属于光催化剂技术领域。为解决目前BiOBr制备方法耗时过长、制备成本高等技术问题,本发明以铋片作为阳极,以惰性电极作为阴极,置于以HF和溴源配置的电解液中,采用电化学方法在2小时内快速制备BiOBr纳米片。本发明所制备的BiOBr结晶度高、物相纯,在可见光照射下显示出对酸性橙Ⅱ良好的光催化降解性能。(A method for rapidly preparing a BiOBr nanosheet belongs to the technical field of photocatalysts. In order to solve the technical problems of overlong time consumption, high preparation cost and the like of the conventional BiOBr preparation method, the bismuth sheet is used as an anode, an inert electrode is used as a cathode, the bismuth sheet is placed in an electrolyte prepared from HF and a bromine source, and the BiOBr nanosheet is quickly prepared within 2 hours by adopting an electrochemical method. The BiOBr prepared by the method has high crystallinity and pure phase, and shows good photocatalytic degradation performance on acid orange II under the irradiation of visible light.)

1. A method for rapidly preparing a BiOBr nanosheet comprises the following steps:

1) mixing HF and a solvent in a certain proportion, adding a bromine source, and taking the mixture as an electrolyte after fully and uniformly mixing;

2) taking a bismuth sheet as an anode and an inert electrode as a cathode, putting the bismuth sheet into the electrolyte obtained in the step 1), adjusting the working voltage and the current density, continuously stirring the electrolyte, and carrying out an electrochemical reaction for a certain time;

3) and 2) after the reaction is finished, drying the substances on the surface of the anode to obtain the BiOBr nano sheet.

2. The method for rapidly preparing BiOBr nanosheets of claim 1, wherein the concentration of HF in step 1) is from 40% to 55%; the solvent is water solution, ethylene glycol or isopropanol; the ratio of HF to solvent is 1: 100-200 parts of; the bromine source is inorganic bromine source (NaBr, KBr), organic bromine source (CTAB) or inorganic and organic bromine source mixed according to different proportions.

3. The method for rapidly preparing BiOBr nano sheets as claimed in claim 1, wherein the bismuth sheet in step 2) is in the form of thin sheet; the inert electrode is Pt, Au, W or C; the working voltage range is 10-30V; the current density range is 50-150 mA/cm²(ii) a The stirring speed range of the electrolyte is 50-300 r/min; the electrochemical reaction time is 0.2-2 h.

4. The method for rapidly preparing BiOBr nano sheets as claimed in claim 1, wherein the drying in step 3) can be natural drying at room temperature or drying below 100 ℃ by using a machine.

5. A BiOBr nanoplate, characterized in that it is prepared by the method of any one of claims 1 to 4.

Technical Field

The invention discloses a method for rapidly preparing a BiOBr nanosheet, belongs to the technical field of photocatalysts, particularly relates to a preparation method of a BiOBr nanosheet photocatalyst, and particularly relates to a preparation method for rapidly preparing a BiOBr nanosheet by adopting an electrochemical method.

Background

TiO since the 70 s of the 20 th century₂Is used as a photocatalytic material, makes important progress in the field of environmental pollution control, and adopts the photocatalyst to treat environmental pollution wastewater, waste gas and solid wasteBecome a research hotspot. But TiO 2₂The forbidden band width of (2) is wide, and only ultraviolet light which accounts for about 4% of sunlight can be utilized, so that the industrialization of the photocatalyst is limited. Therefore, in recent years, narrow bandgap semiconductors that can utilize visible light have been emerging. Among them, bismuth oxyhalide has high stability and a unique structure, and particularly, BiOBr has a suitable forbidden band width, has good absorptivity in a visible light range, shows excellent photocatalytic performance, and is a currently favored semiconductor photocatalytic material.

At present, the preparation method of the BiOBr mainly comprises a soft template method, a hydrothermal method, a hydrolysis method, a deposition method and a high-temperature solid phase method, but the methods are too long in time consumption, so that the preparation cost of the BiOBr is increased, a plurality of unstable factors are increased, and the shape and the stability of the BiOBr are not easy to control. As in the currently granted patent, the preparation of black BiOBr by hydrolysis takes 60 hours only in the standing step (Shangjun, a method for preparing black BiOBr powder material: China, CN201710214818.7[ P ]. 2019-03-12.). The hydrothermal method is adopted to prepare BiOBr, and the hydrothermal reaction time is only 18 hours (Wang-brilliant, a method for preparing flower-shaped BiOBr/sepiolite composite catalyst with the assistance of PVP and the application of the composite catalyst, CN201610546436.X [ P ]. 2019-03-26). Therefore, there is a need to find a more rapid, efficient and effective method for preparing BiOBr, which is suitable for large-scale production.

Disclosure of Invention

The invention provides a method for rapidly preparing BiOBr, aiming at solving the problems that the conventional BiOBr nanosheet preparation method is long in time consumption and difficult in control of morphology and performance, and provides a rapid and efficient preparation method of a BiOBr photocatalyst so as to adapt to large-scale production of the BiOBr photocatalyst. The prepared BiOBr has good crystallization property, moderate band gap and high photocatalytic activity under the irradiation of visible light.

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

A method for rapidly preparing a BiOBr nano sheet adopts an electrochemical method to obtain a required product, and comprises the following steps.

1) HF and a solvent are mixed according to a certain proportion, a bromine source is added, and the mixture is used as an electrolyte after being fully and uniformly mixed.

2) Taking a bismuth sheet as an anode and an inert electrode as a cathode, putting the bismuth sheet into the electrolyte obtained in the step 1), adjusting the working voltage and the current density, and continuously stirring the electrolyte to perform an electrochemical reaction for a certain time.

3) And 2) after the reaction is finished, drying the substances on the surface of the anode to obtain the BiOBr nano sheet.

The ratio of HF to solvent, and the type of solvent, have a large effect on electrolyte performance, and thus on electrolysis efficiency.

Preferably, in the step 1), the concentration of the HF is 40% -55%, and more preferably 40%; the solvent is aqueous solution, ethylene glycol or isopropanol, and more preferably aqueous solution; the ratio of concentrated HF to solvent is 1: 100-200, more preferably 1: 135.

the bromine source has great influence on the crystallization performance of the BiOBr, thereby influencing the morphology and the photocatalytic performance of the BiOBr.

Preferably, in step 1), the bromine source is an inorganic bromine source (NaBr, KBr), an organic bromine source (CTAB) or a mixture of inorganic and organic bromine sources in different proportions, and further preferably NaBr.

Preferably, in the step 1), the bromine source is mixed with the solution by means of magnetic stirring, and ultrasonic treatment is carried out for 30 min.

The shape of the bismuth sheet is also an influencing factor influencing the morphology and physical properties of the BiOBr.

Preferably, in step 2), the bismuth sheet is a sheet, and more preferably a rectangular sheet of 1cm × 2cm × 1 mm.

The kind of the inert electrode has little influence on the electrolytic process, and therefore, Pt, Au, W or C can be used as the inert electrode in the step 2).

Preferably, in step 2), Pt wires with the diameter of 1mm and the length of 10cm are used as the inert electrodes.

The operating voltage and current density affect the electrolysis efficiency and the BiOBr morphology.

Preferably, in the step 2), the working voltage range is 10-30V, and the current density is 50-150 mA/cm²More preferably, the operating voltage is 20V and the current density is 100mA/cm²。

Preferably, in the step 2), a magnetic stirrer is adopted for stirring the electrolyte, and the stirring speed is 50-300 r/min, and more preferably 150 r/min.

Preferably, in the step 2), the electrochemical reaction time is 0.2-2 h, and more preferably 1 h.

Preferably, in step 3), the drying mode can adopt room temperature natural drying or drying at the temperature of below 100 ℃ by using a machine, and further preferably drying at the temperature of 50 ℃ by using an electric hot blast dryer.

Compared with the prior art, the BiOBr catalyst prepared by the method has the following advantages.

1) The preparation method is simple, the reaction condition is mild, the product can be obtained at normal temperature and normal pressure, and the method is suitable for large-scale production.

2) The pH value is not required to be adjusted in the reaction process, and high-temperature calcination is not required, so that the economic cost and the time cost are saved.

3) The BiOBr has good crystallization performance, is in a two-dimensional layered nanosheet structure, and has good effect in visible light catalytic degradation of dyes and phenolic reagents.

Drawings

Fig. 1 is an X-ray diffraction spectrum of BiOBr obtained in the example of the present invention.

Fig. 2 is a transmission electron micrograph of BiOBr obtained in the example of the present invention.

FIG. 3 is a high resolution TEM image of BiOBr obtained in example of the present invention.

Fig. 4 is an ultraviolet-visible diffuse reflection absorption spectrum of BiOBr obtained in the example of the present invention.

FIG. 5 is a graph showing the relationship between the degradation rate of BiOBr photocatalytic degradation of acid orange II and time obtained in the example of the present invention.

Detailed Description

The invention will now be further described with reference to the drawings and specific examples. The examples are not to be construed as limiting the invention.