Niobium-doped bismuth oxybromide catalyst and preparation and use methods thereof
阅读说明：本技术 一种铌掺杂溴氧化铋催化剂及其制备和使用方法 (Niobium-doped bismuth oxybromide catalyst and preparation and use methods thereof ) 是由 董晓丽 尉志苹 王宇 郑楠 于 2020-07-08 设计创作，主要内容包括：本发明提供一种铌掺杂溴氧化铋催化剂及其制备和使用方法,其步骤包括：1、取醇溶剂加热至沸腾并自然冷却；2、依次加入铋盐化合物、铌化合物和溴化合物,混合并充分搅拌；3、加入中性溶液；4、高压恒温反应；5、冷却至室温进行离心分离并分别用水和乙醇溶液洗涤,干燥后收集粉末,得到花球状铌掺杂溴氧化铋。本发明所制备的光催化剂为Nb-BiOBr,具有良好的可见光光催化降解有机物性能,更高的光催化活性以及光生电子空穴分离效率,其降解效率是现有技术中BiOBr的6.4倍,并且环保无害、价格低廉、方法可控、操作简单,在环境污染与治理领域具有广阔的应用前景。(The invention provides a niobium-doped bismuth oxybromide catalyst and a preparation and use method thereof, wherein the preparation method comprises the following steps: 1. heating an alcohol solvent to boiling and naturally cooling; 2. sequentially adding a bismuth salt compound, a niobium compound and a bromine compound, mixing and fully stirring; 3. adding a neutral solution; 4. carrying out high-pressure constant-temperature reaction; 5. cooling to room temperature, performing centrifugal separation, washing with water and ethanol solution respectively, drying, and collecting powder to obtain flower-ball-shaped niobium-doped bismuth oxybromide. The photocatalyst prepared by the invention is Nb-BiOBr, has good performance of photocatalytic degradation of organic matters by visible light, higher photocatalytic activity and photo-generated electron hole separation efficiency, the degradation efficiency is 6.4 times of that of BiOBr in the prior art, and the photocatalyst is environment-friendly, harmless, low in price, controllable in method, simple to operate and wide in application prospect in the field of environmental pollution and treatment.)
1. A niobium-doped bismuth oxybromide catalyst is characterized in that the molecular formula is Nb-BiOBr.
2. The niobium doped bismuth oxybromide catalyst of claim 1, wherein the catalyst is in a structure of a flower sphere.
3. A preparation method of a niobium-doped bismuth oxybromide catalyst is characterized by comprising the following steps:
s1, heating the alcohol solvent to boiling, and cooling to 40-80 ℃;
s2, adding a niobium compound, a bismuth salt compound and a bromine salt compound into the cooled alcohol solvent in the step S1, and fully stirring;
s3, adding the neutral solution into the mixed solution prepared in the step S2, and fully stirring;
s4, reacting the stirred solution in the S3 at a constant temperature of 100-180 ℃ for 10-24 h under the pressure of 1-2 MPa;
and S5, cooling the solution reacted in the step S4 to room temperature, performing centrifugal separation at the rotating speed of 5000-11000 r/m, washing with water and ethanol solution for 2-5 times respectively, drying at the temperature of 50-80 ℃ for 6-12 hours, and collecting powder to obtain the niobium-doped bismuth oxybromide.
4. The method of claim 3, wherein the alcohol solvent in step S1 comprises diethylene glycol, triethylene glycol, isopropanol, ethylene glycol, or glycerol.
5. The method of claim 3, wherein the bismuth salt compound in step S2 comprises bismuth nitrate pentahydrate, bismuth sulfate, or a bismuth ion complex.
6. The method of claim 3, wherein the niobium compound in step S2 comprises niobium oxalate hydrate or niobium oxalate.
7. The method of claim 3, wherein the bromine salt compound in step S2 comprises 2-ethylamine hydrobromide, sodium bromide or potassium bromide.
8. The method of claim 3, wherein the neutral solution in step S3 comprises methanol, isopropanol, ethanol, octanol tert-butyl alcohol or butanol.
9. The method for preparing the niobium doped bismuth oxybromide catalyst according to claim 3, wherein the volume of the filling solution in the step S4 accounts for 60-80% of the high pressure reaction device.
10. The use method of the niobium-doped bismuth oxybromide catalyst is characterized by comprising the following steps of:
s1, adding the catalyst with the concentration of 0.1-1.0 g/L into an organic solution with the concentration of 5-50 mg/L;
s2, stirring for 20-60 min in a dark place, and then stirring for 20-120 min under visible light;
s3, filtering the catalyst by using a filter with the aperture of 0.1-0.4 mu m.
Technical Field
The invention relates to the technical field of photocatalytic materials, in particular to a niobium-doped bismuth oxybromide (Nb-BiOBr) photocatalyst and a preparation method and a use method thereof.
Background
With the rapid development of modern industry and the increase of population, the discharge amount of waste water is increased rapidly, the water pollution condition is more and more serious, and the sustainable development is hindered. Among various water pollution treatment technologies, the photocatalytic technology has the characteristics of low cost, environmental protection and high efficiency, and becomes one of the most promising technologies.
The waste water has high organic content, seriously pollutes the environment, harms the health of people and seriously damages water, soil and an ecological system thereof. The traditional wastewater treatment method has high cost, high energy consumption, low COD removal efficiency, long reaction time and easy secondary pollution. The photocatalysis technology has gained more attention and research in the field of wastewater treatment by utilizing sunlight, high efficiency and low energy consumption. However, the current semiconductor catalyst still has the problems of easy recombination of photo-generated electron holes, low light quantum efficiency, weak surface reaction and the like.
In recent years, bismuth-based semiconductor photocatalysts include BiOX (X ═ Cl, Br, I) and Bi2O3、Bi2MoO6、Bi2WO6、BiVO4Most of the bismuth bromide oxide has visible light response and good photocatalytic effect on pollutants difficult to degrade, particularly bismuth oxybromide (BiOBr), which has the advantages of moderate forbidden band width, stable performance, unique layered structure, simple production process, low price, no toxicity and the like. Nevertheless, conventional BiOBr still exhibits a low organic matter-degrading ability.
Disclosure of Invention
The invention provides a niobium-doped bismuth oxybromide catalyst and a preparation method and a use method thereof, which are used for solving the problems that the conventional semiconductor catalyst still has the defects of easy recombination of photo-induced electron holes, low light quantum efficiency, weak surface reaction, low organic matter degradation capability and the like.
In order to achieve the purpose, the invention provides a niobium-doped bismuth oxybromide catalyst and a preparation method and a use method thereof.
A preparation method of a niobium-doped bismuth oxybromide catalyst comprises the following steps:
s1, heating the alcohol solvent to boiling, and cooling to 40-80 ℃;
s2, adding a bismuth salt compound, a niobium compound and a bromine salt compound into the cooled alcohol solvent in the step S1, and fully stirring for 10-60 min;
s3, adding the neutral solution into the mixed solution prepared in the step S2, and fully stirring;
s4, reacting the stirred solution in the S3 at a constant temperature of 100-180 ℃ for 10-24 h under the pressure of 1-2 MPa;
and S5, cooling the solution reacted in the step S4 to room temperature, performing centrifugal separation at the rotating speed of 5000-11000 r/m, washing with water and ethanol solution for 2-5 times respectively, drying at the temperature of 50-80 ℃ for 6-12 hours, and collecting powder to obtain the niobium-doped bismuth oxybromide.
Wherein the alcohol solvent in step S1 includes diethylene glycol, triethylene glycol, isopropanol, ethylene glycol, or glycerol.
Wherein the bismuth salt compound in step S2 includes bismuth nitrate pentahydrate, bismuth sulfate, or a bismuth ion complex.
Wherein the niobium compound in step S2 includes niobium oxalate hydrate or niobium oxalate.
Wherein, the bromine salt compound in the step S2 includes 2-ethylamine hydrobromide, sodium bromide or potassium bromide.
Wherein the neutral solution in step S3 comprises methanol, isopropanol, ethanol, octanol tert-butyl alcohol or butanol.
Wherein, the volume of the filling solution in the step S4 accounts for 60-80% of the high-pressure reaction device.
The use method of the catalyst comprises the following steps:
s1, adding the catalyst with the concentration of 0.1-1.0 g/L into an organic solution with the concentration of 5-50 mg/L;
s2, stirring for 20-60 min in a dark place, and then stirring for 20-120 min under visible light;
s3, filtering the catalyst by using a filter with the aperture of 0.1-0.4 mu m.
The invention has the following beneficial effects: the photocatalyst prepared by the invention is Nb-BiOBr, has good performance of degrading organic matters by visible light photocatalysis, and has the advantages of high specific surface area, good light absorption, high photocatalytic activity and high photoproduction electron hole separation efficiency. Under visible light, 50mL of rhodamine B with the concentration of 10mg/L can be almost completely degraded by 10mg of photocatalyst Nb-BiOBr within 20min, and the degradation efficiency is 6.4 times that of BiOBr in the prior art. In the prior art, the degradation rate of rhodamine B by using other transition metal elements such as yttrium-doped bismuth oxybromide under the irradiation of visible light for 30min is 98%, and the degradation rate of rhodamine B by using niobium-doped another bismuth oxyhalide bismuth oxychloride under the irradiation of full-wavelength light for 40 min is 99%.
The flower-ball-shaped niobium-doped bismuth oxybromide photocatalyst prepared by the method is environment-friendly, harmless, low in price, controllable in method, simple to operate, obvious in organic matter degradation effect and wide in application prospect in the field of environmental pollution and treatment.
Drawings
FIG. 1 is an XRD diffractogram of the catalyst prepared in example 1 of the present invention;
FIG. 2 is a scanning electron micrograph of a catalyst prepared in example 1 of the present invention;
FIG. 3 is a graph of the UV-vis absorption spectrum of the catalyst prepared in example 1 of the present invention;
FIG. 4 is a spectrum of the forbidden band width estimation of the catalyst prepared in example 1 of the present invention;
FIG. 5 is a graph of current versus time for the catalyst prepared in example 1 of the present invention;
FIG. 6 is a graph showing the AC impedance of the catalyst prepared in example 1 of the present invention;
FIG. 7 is a graph showing the effect of photocatalytic degradation of organic substances in catalysts prepared in examples 1 to 6 of the present invention.
Detailed Description
The invention relates to a preparation method of a flower-ball-shaped Nb-BiOBr photocatalyst, which comprises the following steps: 1. heating an alcohol solvent to boiling and naturally cooling; 2. sequentially adding a bismuth salt compound, a niobium compound and a bromine compound, mixing and fully stirring; 3. adding a neutral solution; 4. carrying out high-pressure constant-temperature reaction; 5. cooling to room temperature, performing centrifugal separation, washing with water and ethanol solution respectively, drying, and collecting powder to obtain flower-ball-shaped niobium-doped bismuth oxybromide.
Specifically, the method comprises the following steps: s1, heating 5-90 mL of diethylene glycol, triethylene glycol, isopropanol, ethylene glycol or glycerol serving as an alcohol solvent to boil, and cooling to 40-80 ℃; the alcohol solvent comprises diethylene glycol, triethylene glycol, isopropanol, ethylene glycol or glycerol and the like.
S2, adding 0.1-1.5 g of bismuth salt compound, 0.001-0.05 g of niobium compound and 0.02-0.5 g of bromine salt compound into the alcohol solution, mixing and fully stirring for 10-60 min; the bismuth salt compound comprises bismuth nitrate pentahydrate, bismuth sulfate or bismuth ion complex and the like; the niobium compound includes niobium oxalate hydrate or niobium oxalate and the like; the bromine salt compound includes 2-ethylamine hydrobromide, sodium bromide or potassium bromide and the like.
S3, adding the neutral solution into the mixed solution prepared in the S2, and fully stirring; the neutral solution comprises methanol, isopropanol, ethanol, octanol tert-butyl alcohol or butanol and the like;
s4, putting the stirred solution in the S3 into a 1-2 MPa high-pressure reaction kettle, and carrying out constant-temperature reaction at 100-180 ℃ for 10-24 h;
s5, cooling the reacted solution in the S4 to room temperature, performing centrifugal separation at the rotation speed of 5000-. Wherein, during the synthesis reaction, the volume of the filling solution accounts for 60-80% of the volume of the inner lining of the autoclave.
The use method of the invention comprises the following steps: adding the catalyst prepared by the invention into 40-150 mL of organic solution with the concentration of 5-50 mg/L, wherein the concentration of the catalyst is 0.1-1.0 g/L, stirring for 20-60 min in a dark place before photocatalysis, then stirring for 20-120 min under visible light, and filtering the catalyst by using a filter with the pore diameter of 0.1-0.4 mu m.