CN103263906A - Nanocrystal tin oxide photocatalyst and preparation method thereof - Google Patents

Abstract

The invention discloses a nano-crystalline tin oxide photocatalyst, the grain size of the tin oxide powder is 10-20nm, the tin oxide particle size is 200-300nm, and the surface of the tin oxide particle has prisms. The preparation method of the nanocrystalline tin oxide photocatalyst of the present invention, through the design and optimization of the particle size and controllable morphology of the tin oxide surface composition, greatly improves its degradation efficiency for pollutants, and solves the problem of the narrow application range of the existing photocatalyst , the problem of poor catalytic performance.

Description

A kind of nanocrystalline tin oxide photocatalyst and preparation method thereof

technical field

The invention belongs to the technical field of nanomaterials and photocatalysis, and relates to a semiconductor photocatalyst, in particular to a nanocrystalline tin oxide photocatalyst, and also relates to a preparation method of the nanocrystalline tin oxide photocatalyst.

Background technique

Due to its small size and large specific surface area, nano-tin oxide has a high proportion of surface atoms and many suspended chemical bonds, which increases the activity of nanomaterials, and the existence of a large number of dangling bonds makes the interface polarized, while the high specific surface area causes multiple scattering. At the same time, it has low preparation temperature and high chemical stability, which makes it widely used in ceramics, transparent conductive materials, luminescent materials, flat panel displays, solar cells, gas sensors, catalysts, etc. Therefore, the preparation of tin oxide ultrafine powder with high purity, uniform shape, fine grain size and no agglomeration has been a research hotspot in recent years.

With the rapid development of global industrialization, the problem of environmental pollution is becoming more and more serious. Controlling pollution, protecting the environment and achieving sustainable development has become the consensus of the world, and pollution treatment has therefore become an important research content for scientific researchers. Semiconductor photocatalysis has the advantages of fast degradation, complete degradation, energy saving, and reusability, and has become an attractive new technology in the field of pollutant treatment. At present, the common materials used as photocatalysts are TiO ₂ , ZnO, SnO ₂ , WO ₃ , ZrO ₂ , Nb ₂ O ₅ , Fe ₂ O ₃ , SrTiO ₃ , BaTiO ₃ , CdO and other oxides, CuS, ZnS and other sulfides. compounds, selenides such as CdSe and SiC, GaP, GaAs. SnO ₂ nanomaterials have excellent photocatalytic activity, but the wide band gap (3.8eV) of SnO ₂ requires ultraviolet light excitation, thus limiting the application of SnO ₂ . In order to obtain photocatalysts excited by visible light, it must be modified, including crystal morphology control, doping, surface sensitization, composite materials, etc. Recent studies have found that V-shaped small-sized tin oxide crystals show better photocatalytic performance under visible light irradiation. For the research on the photocatalytic reaction mechanism, most people think that the particle size, crystal structure and surface morphology of the catalyst are the main factors that determine the photocatalytic activity, so the preparation of nano-tin oxide with different morphology and structure and its photocatalytic performance research is of great significance.

Contents of the invention

The purpose of the present invention is to provide a nanocrystalline tin oxide photocatalyst, through the design and optimization of the particle size and controllable morphology of the surface composition of tin oxide, greatly improve its degradation efficiency of pollutants, and solve the problem of existing photocatalysts. Narrow application range and poor catalytic performance.

Another object of the present invention is to provide a preparation method of the above-mentioned nanocrystalline tin oxide photocatalyst.

The technical scheme adopted in the invention is a nanocrystalline tin oxide photocatalyst, the grain size of the tin oxide powder is 10-20nm, the tin oxide particle size is 200-300nm, and the surface of the tin oxide particle has prisms.

Another technical scheme adopted in the present invention is a preparation method of nanocrystalline tin oxide photocatalyst, specifically implemented according to the following steps:

Step 1: take tin protochloride and dissolve it in deionized water under magnetic stirring to obtain a white solution;

Step 2: Add sodium hydroxide to the white solution obtained in step 1, and continue stirring until the solution becomes transparent;

Step 3: Slowly add hydrogen peroxide with a mass concentration of 30% into the solution obtained in step 2, and stir;

Step 4: Add polyvinylpyrrolidone to the solution obtained in step 3, and stir until fully dissolved to obtain a polyvinylpyrrolidone solution;

Step 5: Transfer the solution obtained in step 4 to a reaction kettle lined with polytetrafluoroethylene, microwave hydrothermal heating at 160-200°C for 30-90 minutes, and naturally cool to room temperature after the reaction to obtain a white precipitate, which is collected The precipitated product was washed with deionized water and absolute ethanol successively, and dried in a vacuum oven at 60° C. for 12 hours to obtain the nanocrystalline tin oxide photocatalyst of the present invention.

The present invention is also characterized in that,

The mass-volume concentration of the white solution in step 1 is 1:40g/mL～1:8g/mL.

The mass ratio of white solution to sodium hydroxide in step 2 is 1:40-4.

The volume ratio of hydrogen peroxide to the solution in step 3 is 1:20-2.

Wherein the stirring time in step 3 is 2～10 minutes.

The mass-volume concentration of the polyvinylpyrrolidone solution in step 4 is 1:50g/mL-1:10g/mL.

The beneficial effect of the present invention is,

The microwave hydrothermal method used in the present invention combines the traditional hydrothermal method with the microwave field, and has both the heat source of microwave and the advantages of hydrothermal method itself, and has the advantages of rapid and uniform heating, no temperature gradient, accelerated chemical reaction, etc. advantage.

In the present invention, the microwave hydrothermal temperature is a key factor affecting the crystallinity and morphology of the nanocrystalline tin oxide material, and the crystallinity and morphology of the nanocrystalline tin oxide material obtained at different temperatures are different.

In the present invention, the microwave hydrothermal time affects the dispersibility and morphology of the nanocrystalline tin oxide material, and too long reaction time will affect the dispersibility and microscopic morphology of the nanocrystalline tin oxide material. Through the microwave hydrothermal method induced by surfactants, the selected crystalline stannous chloride (tin source), sodium hydroxide (alkali source), hydrogen peroxide (oxidant), and polyvinylpyrrolidone (surfactant) are all low in price, and prepared The nanocrystalline tin oxide photocatalytic material has uniform morphology, small size, uniform particle size distribution, and good monodispersity.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of the nanocrystalline tin oxide photocatalytic material prepared by the embodiment of the present invention 2;

Fig. 2 is the scanning electron micrograph of the nanocrystalline tin oxide photocatalytic material prepared in Example 3 of the present invention, wherein a is a scanning electron micrograph enlarged 5000 times, and b is a scanning electron micrograph enlarged 20000 times;

Fig. 3 is the scanning electron microscope photograph of the nanocrystalline tin oxide photocatalytic material prepared in Example 4 of the present invention, wherein a is a scanning electron microscope photograph enlarged 5000 times, and b is a scanning electron microscope photograph enlarged 20000 times;

Fig. 4 is the photocatalytic rhodamine B degradation curve of the nanocrystalline tin oxide photocatalytic material prepared in Example 5 of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The nanocrystalline tin oxide photocatalyst of the present invention is characterized in that: the grain size of the tin oxide powder is 10-20nm, the particle size is 200-300nm, there are small prisms on the surface of the tin oxide particles, and the photocatalytic degradation of rhodamine B experiment shows that : Nanocrystalline tin oxide has high photocatalytic activity.

The preparation method of nanocrystalline tin oxide photocatalyst of the present invention, specifically implement according to the following steps:

Step 1: Weigh stannous chloride and dissolve it in deionized water under magnetic stirring to form a white solution. The mass-volume concentration of the obtained white solution is 1:40g/mL～1:8g/mL;

Step 2: Add sodium hydroxide to the solution obtained in step 1 and continue to stir until the solution becomes transparent, and the mass ratio of white solution to sodium hydroxide is 1:40~1:4;

Step 3: Slowly add 30% hydrogen peroxide dropwise to the solution obtained in step 2, and stir for 2 to 10 minutes; the volume ratio of hydrogen peroxide to the solution is 1:20 to 1:2;

Step 4: Add polyvinylpyrrolidone to the solution obtained in step 3, stir to make it fully dissolve to form a uniform solution, and the mass-volume concentration of the obtained polyvinylpyrrolidone solution is 1:50g/mL～1:10g/mL;

Step 5: Transfer the solution obtained in step 4 to a 100mL reaction kettle lined with polytetrafluoroethylene, and heat it in microwave water at 160-200°C for 30-90 minutes in a microwave digestion apparatus. After the reaction, cool naturally to room temperature to obtain a white Precipitate, collect the precipitated product and sequentially wash it with deionized water and absolute ethanol, and place it in a vacuum drying oven at 60° C. for 12 hours to obtain the nanocrystalline tin oxide photocatalyst of the present invention.

Example 1

Weigh stannous chloride and dissolve it in deionized water under magnetic stirring to form a white solution; the mass-volume concentration of the obtained solution is 1:40g/mL; add sodium hydroxide to the above obtained solution and continue stirring until the solution becomes Transparent; the mass ratio of white solution to sodium hydroxide is 1:4; slowly add 30% hydrogen peroxide dropwise to the solution obtained above, and stir for 10 minutes; the volume ratio of hydrogen peroxide to solution is 1:10; Add polyvinylpyrrolidone into the solution, stir it to fully dissolve to form a uniform solution; the mass-volume concentration of the obtained polyvinylpyrrolidone solution is 1:50g/mL; transfer the above-mentioned solution to a 100mL Teflon-lined In the reaction kettle, microwave hydrothermal heating at 160°C for 90 minutes in a microwave digestion apparatus. After the reaction, naturally cool to room temperature to obtain a white precipitate. Collect the precipitated product and wash it centrifugally with deionized water and absolute ethanol, and place it in a vacuum drying oven at 60°C. Dry for 12 hours to obtain nanocrystalline tin oxide powder.

Example 2

Weigh stannous chloride and dissolve it in deionized water under magnetic stirring to form a white solution; the mass-volume concentration of the obtained solution is 1:20g/mL; add sodium hydroxide to the above obtained solution and continue stirring until the solution becomes Transparent; the mass ratio of white solution to sodium hydroxide is 1:8; slowly add 30% hydrogen peroxide dropwise to the solution obtained above, and stir for 7 minutes; the volume ratio of hydrogen peroxide to solution is 1:20; Add polyvinylpyrrolidone into the solution, stir to make it fully dissolve to form a uniform solution; the mass-volume concentration of the obtained polyvinylpyrrolidone solution is 1:10g/mL; In the reaction kettle, microwave hydrothermal heating at 180°C for 30 minutes in a microwave digestion apparatus. After the reaction, naturally cool to room temperature to obtain a white precipitate. Collect the precipitated product and wash it centrifugally with deionized water and absolute ethanol, and place it in a vacuum drying oven at 60°C. Dry for 12 hours to obtain nanocrystalline tin oxide powder. Figure 1 is the X-ray diffraction (XRD) pattern of the prepared nanocrystalline tin oxide. It can be seen from the figure that the product has a tetragonal rutile structure with high crystallinity and high purity.

Example 3

Weigh stannous chloride and dissolve it in deionized water under magnetic stirring to form a white solution; the mass-volume concentration of the obtained solution is 1:30g/mL; add sodium hydroxide to the above obtained solution and continue stirring until the solution becomes Transparent; the mass ratio of white solution to sodium hydroxide is 1:40; slowly add 30% hydrogen peroxide dropwise to the solution obtained above, and stir for 5 minutes; the volume ratio of hydrogen peroxide to solution is 1:8; Add polyvinylpyrrolidone into the solution, stir it to fully dissolve to form a uniform solution; the mass-volume concentration of the obtained polyvinylpyrrolidone solution is 1:25g/mL; transfer the above-mentioned solution to a 100mL Teflon-lined In the reaction kettle, microwave hydrothermal heating at 200°C for 60 minutes in a microwave digestion apparatus. After the reaction, naturally cool to room temperature to obtain a white precipitate. Collect the precipitated product and centrifugally wash it with deionized water and absolute ethanol, and place it in a vacuum drying oven at 60°C. Dry for 12 hours to obtain nanocrystalline tin oxide powder. Fig. 2 is a scanning electron microscope photo of the prepared nanocrystalline tin oxide. It can be seen from the figure that the product is spherical, and the surface of the spherical particles has small prisms with square cross-sections.

Example 4

Weigh stannous chloride and dissolve it in deionized water under magnetic stirring to form a white solution; the mass-volume concentration of the obtained solution is 1:8g/mL; add sodium hydroxide to the above obtained solution and continue stirring until the solution becomes Transparent; the mass ratio of white solution to sodium hydroxide is 1:10; slowly add 30% hydrogen peroxide dropwise to the solution obtained above, and stir for 8 minutes; the volume ratio of hydrogen peroxide to solution is 1:2; Add polyvinylpyrrolidone into the solution, stir to make it fully dissolve to form a uniform solution; the mass-volume concentration of the obtained polyvinylpyrrolidone solution is 2:25g/mL; In the reaction kettle, microwave hydrothermal heating at 185°C for 75 minutes in a microwave digestion apparatus. After the reaction, naturally cool to room temperature to obtain a white precipitate. Collect the precipitated product and wash it centrifugally with deionized water and absolute ethanol, and place it in a vacuum drying oven at 60°C. Dry for 12 hours to obtain nanocrystalline tin oxide powder. Figure 3 is a scanning electron microscope photo of the prepared nanocrystalline tin oxide. It can be seen from the figure that the appearance of the tin oxide powder is uniform, the grain size is as small as 18nm, the particle size is about 200-300nm, and the monodispersity good.

Example 5

Weigh stannous chloride and dissolve it in deionized water under magnetic stirring to form a white solution; the mass-volume concentration of the obtained solution is 1:12g/mL; add sodium hydroxide to the above obtained solution and continue stirring until the solution becomes Transparent; the mass ratio of white solution to sodium hydroxide is 1:20; slowly add 30% hydrogen peroxide dropwise to the solution obtained above, and stir for 2 minutes; the volume ratio of hydrogen peroxide to solution is 1:4; Add polyvinylpyrrolidone into the solution, stir to make it fully dissolve to form a uniform solution; the mass-volume concentration of the obtained polyvinylpyrrolidone solution is 3:50g/mL; In the reaction kettle, microwave hydrothermal heating at 170°C for 80 minutes in a microwave digestion apparatus. After the reaction, naturally cool to room temperature to obtain a white precipitate. Collect the precipitated product and centrifugally wash it with deionized water and absolute ethanol, and place it in a vacuum drying oven at 60°C. Dry for 12 hours to obtain nanocrystalline tin oxide powder. Fig. 4 is the photocatalytic rhodamine B degradation curve of the prepared nanocrystalline tin oxide powder. It can be seen from the degradation curve that the prepared nanocrystalline tin oxide photocatalytic material has a high degradation efficiency for rhodamine B in water.

The key parameter scope of the present invention is the mass-volume concentration of tin protochloride solution, the mass ratio of white solution and sodium hydroxide and the mass-volume concentration of polyvinylpyrrolidone solution; The hydrolysis of stannous oxide can be used to prepare nano tin oxide powder with controllable morphology. Greater or less than this parameter range will cause problems in the preparation of nano-tin oxide with controllable morphology due to the absence or saturation of source materials, improper system pH and unreasonable dosage of template agent polyvinylpyrrolidone.

Claims (7)

1. a nanocrystalline tin oxide photochemical catalyst is characterized in that the crystallite dimension of tin oxide powder is 10～20nm, and granules of stannic oxide is of a size of 200～300nm, and there is prism on the granules of stannic oxide surface.

2. the preparation method of a nanocrystalline tin oxide photochemical catalyst is characterized in that, the nanocrystalline tin oxide photochemical catalyst for preparing, and the crystallite dimension of tin oxide powder is 10～20nm, and granules of stannic oxide is of a size of 200～300nm, and there is prism on the granules of stannic oxide surface;

Specifically implement according to following steps:

Step 1: take by weighing stannous chloride and under magnetic agitation, be dissolved in deionized water and obtain white solution;

Step 2: in the white solution of step 1 gained, add NaOH, continue stirring until solution and become transparent;

Step 3: be that 30% hydrogen peroxide slowly is added drop-wise in the solution of step 2 gained with mass concentration, stir;

Step 4: in the solution of step 3 gained, add polyvinylpyrrolidone, be stirred to abundant dissolving, obtain polyvinylpyrrolidonesolution solution;

Step 5: the solution of step 4 gained is transferred in the band teflon-lined reactor, microwave hydrothermal 30～90min under 160～200 ℃ of conditions, reaction naturally cools to room temperature after finishing, obtain white precipitate, the collecting precipitation product is also used deionized water, absolute ethyl alcohol centrifuge washing successively, place 60 ℃ of dry 12h of vacuum drying chamber, obtain the nanocrystalline tin oxide photochemical catalyst of the present invention.

3. the preparation method of nanocrystalline tin oxide photochemical catalyst according to claim 2 is characterized in that, the quality-volumetric concentration of white solution is 1:40g/mL～1:8g/mL in the described step 1.

4. the preparation method of nanocrystalline tin oxide photochemical catalyst according to claim 2 is characterized in that, the mass ratio of white solution and NaOH is 1:40～4 in the described step 2.

5. the preparation method of nanocrystalline tin oxide photochemical catalyst according to claim 2 is characterized in that, the volume ratio of hydrogen peroxide and solution is 1:20～2 in the described step 3.

6. the preparation method of nanocrystalline tin oxide photochemical catalyst according to claim 2 is characterized in that, mixing time is 2～10 minutes in the described step 3.

7. the preparation method of nanocrystalline tin oxide photochemical catalyst according to claim 2 is characterized in that, the quality-volumetric concentration of polyvinylpyrrolidonesolution solution is 1:50g/mL～1:10g/mL in the described step 4.

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