阅读说明：本技术 一种超薄团簇状BiOBr纳米光催化剂的制备方法 (Preparation method of ultrathin clustered BiOBr nano photocatalyst ) 是由 朵芳芳 张明亮 褚亮亮 王储备 周建伟 于 2019-11-06 设计创作，主要内容包括：一种超薄团簇状BiOBr纳米光催化剂的制备方法,属于化学功能材料技术领域,可解决现有的BiOBr调控形貌的制备过程中使用了醇类溶剂加热分解后会产生醚类,或添加强碱会产生大量的废水,造成环境污染的问题,本发明采用非离子型聚丙烯酰胺作为晶体成核桥联剂,促进BiOBr由纳米片组装成超薄团簇状,无需加入醇类或强碱等仅需控制反应时间就能得到不同形貌的BiOBr。(A preparation method of an ultrathin cluster-shaped BiOBr nano photocatalyst belongs to the technical field of chemical function materials and can solve the problems that ethers are generated after an alcohol solvent is used for heating and decomposing in the existing preparation process of BiOBr regulation and control morphology, or a large amount of waste water is generated by adding strong base to cause environmental pollution.)

1. A preparation method of an ultrathin cluster-shaped BiOBr nano photocatalyst is characterized by comprising the following steps: the method comprises the following steps:

firstly, adding bismuth nitrate pentahydrate into absolute ethyl alcohol according to a proportion, and stirring for 0.5-1 h at room temperature to obtain a white suspension A;

step two, dripping 20mL of polyacrylamide aqueous solution into the white suspension A in the step one, stirring for 10-30 min, and performing ultrasonic dispersion for 0.5-1 h to obtain a white suspension B;

thirdly, dropwise adding a bromide aqueous solution into the white turbid liquid B obtained in the second step, and stirring for 1-3 hours to obtain a uniform light yellow turbid liquid;

fourthly, transferring the light yellow suspension obtained in the third step into a sealed polytetrafluoroethylene high-pressure reaction kettle, heating to 150-180 ℃, and reacting at constant temperature for 4-12 hours to obtain light yellow precipitate;

and fifthly, washing the light yellow precipitate obtained in the fourth step with water and ethanol, and drying for 5-12 hours at the temperature of 60-80 ℃ to obtain the ultrathin cluster-shaped BiOBr nano photocatalyst.

2. The preparation method of the ultrathin clustered BiOBr nano photocatalyst as claimed in claim 1, wherein the preparation method comprises the following steps: the proportion of the bismuth nitrate pentahydrate to the absolute ethyl alcohol in the first step is 0.05-0.1 mol/L.

3. The preparation method of the ultrathin clustered BiOBr nano photocatalyst as claimed in claim 1, wherein the preparation method comprises the following steps: the concentration of the polyacrylamide aqueous solution in the second step is 10-20 g/L.

4. The preparation method of the ultrathin clustered BiOBr nano photocatalyst as claimed in claim 1, wherein the preparation method comprises the following steps: in the third step, the bromide comprises any one of sodium bromide, potassium bromide and ammonium bromide, the addition amount of the bromide is 1-5 mmol, and the volume of water is 10-30 mL.

Technical Field

The invention belongs to the technical field of chemical functional materials, and particularly relates to a preparation method of an ultrathin clustered BiOBr nano photocatalyst.

Background

With the rapid development of modern city industrialization, energy and environmental problems are prominent day by day, which has serious impact on people's life and health. Semiconductor photocatalysis based on solar energy utilization and conversion is a novel green and advanced (deep) oxidation technology which is carried out at normal temperature and normal pressure, and can be used for decomposing water to produce hydrogen, degrading toxic organic pollutants and converting CO₂The carbon fuel is reduced into other carbon fuels and the like, and is considered to be a high-efficiency, green and promising technology for realizing energy source replacement and environmental purification. However, the low utilization rate of the semiconductor photocatalytic material to solar energy is always a key problem for restricting the photocatalysis from basic research to industrial application.

Bismuth oxyhalide (BiOX), a photocatalyst having a specific layered structure and an indirect band gap, has received much attention from researchers due to its excellent photocatalytic performance. Among them, bismuth oxybromide (BiOBr) is considered to be a photocatalyst with a great application prospect due to its high visible light catalytic performance and stability. Since the photocatalytic reaction is mainly carried out on the surface of the catalyst, the surface structure of the photocatalyst has a great influence on the photocatalytic performance of the photocatalyst. Therefore, the regulation and control research on the BiOBr morphology is very important. For example, the BiOBr microspheres are prepared by adopting a solvothermal method by Ma and the like (Catalysis Communications, 2018, 106, 1-5), taking ethanol as a solvent and a template agent simultaneously, and taking mirabilite pentahydrate and sodium bromide as raw materials. Zhang et al (J. am. chem. Soc.2012134473-4476) reported that BiOCl nanosheets are obtained by using mirabilite pentahydrate and sodium chloride as raw materials and adjusting the pH value with sodium hydroxide. In the preparation process of the BiOBr regulation and control morphology reported in the prior art, an alcohol solvent is used for heating and decomposing to generate ethers or add strong base, so that a large amount of waste water is generated, and the environmental pollution is caused. Therefore, a more environmentally friendly method for regulating the microscopic morphology of the BiOBr is needed.

Disclosure of Invention

The invention provides a preparation method of an ultrathin cluster-shaped BiOBr nano photocatalyst, aiming at the problems that in the existing preparation process of BiOBr controlled morphology, after an alcohol solvent is used for heating and decomposing, ethers are generated or strong base is added, a large amount of waste water is generated, and environmental pollution is caused.

The invention adopts the following technical scheme:

a preparation method of an ultrathin cluster-shaped BiOBr nano photocatalyst comprises the following steps:

firstly, adding bismuth nitrate pentahydrate into absolute ethyl alcohol according to a proportion, and stirring for 0.5-1 h at room temperature to obtain a white suspension A;

step two, dripping 20mL of polyacrylamide aqueous solution into the white suspension A in the step one, stirring for 10-30 min, and performing ultrasonic dispersion for 0.5-1 h to obtain a white suspension B;

thirdly, dropwise adding a bromide aqueous solution into the white turbid liquid B obtained in the second step, and stirring for 1-3 hours to obtain a uniform light yellow turbid liquid;

fourthly, transferring the light yellow suspension obtained in the third step into a sealed polytetrafluoroethylene high-pressure reaction kettle, heating to 150-180 ℃, and reacting at constant temperature for 4-12 hours to obtain light yellow precipitate;

and fifthly, washing the light yellow precipitate obtained in the fourth step with water and ethanol, and drying for 5-12 hours at the temperature of 60-80 ℃ to obtain the ultrathin cluster-shaped BiOBr nano photocatalyst.

The proportion of the bismuth nitrate pentahydrate to the absolute ethyl alcohol in the first step is 0.05-0.1 mol/L.

The concentration of the polyacrylamide aqueous solution in the second step is 10-20 g/L.

In the third step, the bromide comprises any one of sodium bromide, potassium bromide and ammonium bromide, the addition amount of the bromide is 1-5 mmol, and the volume of water is 10-30 mL.

The principle of the invention is as follows:

non-ionic polyacrylamide (NPAM) was used as a bridging agent for crystal nucleation. In the strong acid environment, NPAM has the functions of a bridge and a flocculating agent, amide groups in the NPAM are strong electron-withdrawing groups and are compatible with bismuth atoms in the bismuth subnitrate, and the long-chain structure of the NPAM bridges among adsorbed particles to generate floccules. After potassium bromide is added, BiOBr is generated in situ, through heating treatment in a closed reaction kettle, the BiOBr crystal nucleus gradually grows up and the surface energy is changed, the exposure of a crystal face is determined by the height of the surface energy, the growth direction of the crystal is influenced, and along with the extension of constant-temperature reaction time, the cluster grows and the nanosheets become thin, so that the BiOBr nano photocatalyst assembled into a cluster by the nanosheets is obtained.

The invention has the following beneficial effects:

according to the invention, non-ionic polyacrylamide is added as a bridging agent in the reaction process of bismuth nitrate pentahydrate and potassium bromide, and the size of clusters and the thickness of the nanosheets are controlled by controlling the reaction time. The used reagents are cheap and easy to obtain, the cost is lower, the preparation process is simple and easy to control, the yield is high, the repeatability is good, and the method is suitable for popularization and application. The catalyst has stronger degradation capability to organic pollutants (such as dye, antibiotics and the like) under visible light, and the catalyst has high reutilization ratio. Can be practically applied to the environmental protection fields of photocatalytic sewage treatment, air purification and the like.

Drawings

Fig. 1 is an XRD spectrum of the BiOBr nanomaterial prepared in example 1 of the present invention and comparative example 1.

Fig. 2 is an SEM spectrum of the BiOBr nanomaterial prepared in comparative example 1 of the present invention.

FIG. 3 is a photo-catalytic degradation spectrum of the BiOBr nano material prepared in example 1 and comparative example 1 of the present invention for rhodamine B solution.

Fig. 4 is a photocatalytic degradation spectrum of the BiOBr nanomaterial prepared in the embodiment 1 and the comparative example 1 of the present invention on ciprofloxacin hydrochloride solution.

Fig. 5 is an SEM spectrum of the BiOBr nanomaterial prepared in example 2 of the present invention.

Detailed Description