Preparation method of titanium dioxide having fixed crystalline phase composition and doped with different contents of iron

Preparation method of iron-doped titanium dioxide with different content of fixed crystal phase compositionTechnical field

[0001] The present invention relates to a preparation method of iron-doped titanium dioxide with different content of fixed crystal phase composition, and its application in the fields of photocatalysis, self-cleaning and solar cells.

Background technique

[0002] Titanium dioxide, as a highly efficient, non-toxic, chemically and physically stable photocatalytic material, has attracted people's attention widely, and it has been used in the production of hydrogen by water splitting, photoreduction of carbon dioxide to prepare fuel, and the degradation of organic pollutants in the environment A certain degree of progress. The current practical applications of titanium dioxide mainly focus on photocatalytic degradation of environmental organic pollutants. In terms of the degradation of organic pollutants, there are two main restrictions on the wide application of titanium dioxide: First, the forbidden band width of titanium dioxide is relatively wide (3.2 eV), so it can only use the ultraviolet part of sunlight, which only accounts for sunlight energy. The second is that the adsorption performance of titanium dioxide itself is poor, and the degradation reaction occurs on the surface of the photocatalyst. Therefore, only the organic pollutants that come into contact with the surface can be degraded in the reaction. In order to improve its adsorption performance, most reports have adopted the method of combining titanium dioxide with strong adsorption materials (such as apatite, activated carbon, graphene, etc.) to form a composite material to improve its adsorption performance. Currently, the mixed crystal composition and the doping of anions and cations have been proved to be able to effectively improve the responsiveness of the titanium dioxide photocatalyst to visible light. At present, there have been many reports about iron doping to improve the photocatalytic activity of titanium dioxide, and there are also some reports about iron doping in mixed crystal structure. However, since the doping of iron can promote the transformation of rutile phase to anatase phase, it has not been reported to stabilize the crystalline phase of titanium dioxide and doping with different content of iron in this process.

Summary of the invention

[0003] The object of the present invention is to provide a visible light-responsive photocatalytic material co-doped with iron and tin with an adjustable crystal phase of titanium dioxide. The crystal phase of the material can be adjusted in a wide range, and different crystals can be adjusted. The comparative example is doped with a series of different contents of iron, but the crystal phase composition is not affected, and the prepared photocatalyst has higher reaction activity in the visible light photocatalytic reaction.

[0004] The present invention provides a method for preparing a visible light-responsive photocatalytic material co-doped with iron and tin with crystalline phases, and the specific steps are:

[0005] 1) Take a certain amount of titanium precursor, mix it with different amounts of iron and tin salts, and heat it to 30° C-100° C in a water bath;

[0006] 2) Add an appropriate amount of a certain concentration of H₂0₂Add the solution to the mixed solution and stir to mix evenly.

Incubate in a 30° C-100° C water bath for 0.5-4 hours;

[0007] 3) Put the obtained gel in an oven above 60°C for drying;

[0008] 4) Grind the dried powder and burn it at 300-500°M for 2-8h.

[0009] The titanium precursor is one of tetraisopropyl titanate, tetraisobutyl titanate, and titanium tetrachloride, and the iron salt is iron nitrate, iron chloride, iron sulfate, acetyl One of acetone iron, and the tin salt is one of tin tetrachloride, stannous chloride, and stannous oxalate.

[0010] The method for evaluating the photocatalytic performance of titanium dioxide provided by the present invention is as follows:

[0011] Evaluation of photocatalytic performance: After the adsorption reached equilibrium for half an hour, the 400nm long wave pass filter was opened and loaded

The reaction vessel was irradiated with a 300W magic emanation lamp to perform visible light degradation experiments, and samples were taken at regular intervals during the reaction process, and the supernatant was centrifuged to take the supernatant and use an ultraviolet-visible spectrophotometer to measure it to determine the degree of degradation of the methylene blue solution .

[0012] The prepared titanium dioxide has strong adsorption performance and activity in the photocatalytic reaction of visible light photocatalytic degradation of organic pollutants. In the visible light photocatalytic reaction of trace gas phase and liquid phase, the same proportion of titanium dioxide photocatalytic material has extremely high adsorption performance and activity. And the crystal phase composition can be continuously adjusted in a larger range.

[0013] The present invention has the following advantages:

[0014] The crystalline phase of the prepared titanium dioxide photocatalytic material can be adjusted in a large range (rutile ratio 0^100%); a series of titanium dioxide doped with different iron content can be synthesized in a relatively simple manner under different crystal phases. Photocatalyst, and the prepared iron and tin co-doped titanium dioxide has strong adsorption performance and photocatalytic activity in the visible light photocatalytic reaction.

Description of the drawings

[0015] FIG. 1 is an XRD spectrum of Examples 1-6. From the spectrum, it can be found that the prepared titanium dioxide photocatalyst contains two phases of anatase and rutile. Calculated according to Schiller's formula, it is found that the size of the particles are all around 20nm. And according to the formula F_e=1/[1+0.8 is called (101) /Ir (110)], it can be calculated that the proportion of anatase ranges from 0% to 100%, and its composition ratio is continuously adjustable within this interval.

[0016] FIG. 2 is an XRD pattern of Examples 3 and 7-10 of different iron content doping. It can be found from the figure that the iron doping content has almost no effect on the crystalline phase composition of titanium dioxide.

4 [0017] FIG. 3 is the ultraviolet-visible diffuse reflectance absorption spectra of Examples 1 to 6. It can be found from the figure that the doping of tin can promote the light absorption performance of the titanium dioxide sample to a certain extent, but when the doping amount is greater than 0.4 After %, continuous tin doping has little effect on its light absorption performance.

[0018] FIG. 4 is the ultraviolet-visible diffuse reflectance absorption spectra of Examples 3 and 7-10. It can be found from the figure that the doping of iron can continue to improve the light absorption capacity of titanium dioxide on the basis of tin doping, and the light absorption capacity varies with To increase the iron doping content.

[0019] FIG. 5 is a visible light photocatalytic performance evaluation spectrum of the titanium dioxide photocatalytic nanoparticles of Examples 1, 3, and 8 and the comparative commercial titanium dioxide P-25 (Degussa). It can be drawn from the figure that the photocatalytic performance and adsorption performance of the prepared iron and tin co-doped titanium dioxide photocatalyst have been greatly improved, and the photocatalytic performance has reached 4.5 times that of P-25.

[0020] FIG. 6 is a TEM electron micrograph, A, B, and C are the TEM electron micrographs of the samples prepared in Example & 9, 10, respectively. It can be seen from the TEM photos that the size of the particles is about 20 nm, which is in good agreement with the XRD results, and the titanium dioxide in Example 10 is rod-shaped and relatively uniform.

Detailed ways

Example 1

[0022] Add 2ml of tetraisopropyl titanate in a 1L beaker, and then slowly add 30ml of H with a mass fraction of 30%₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder was ground and burned in a muffle furnace at 500°M for 4h. And the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 2

[0024] Add 2ml of tetraisopropyl titanate and 0.0028g of stannous oxalate in a 1L beaker, and then slowly add 30ml of H with a mass fraction of 30%₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder was ground and burned in a muffle furnace at 500°M for 4 hours. And the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 3

[0026] Add 2ml of tetraisopropyl titanate and 0.0056g of stannous oxalate in a 1L beaker, and then slowly add 30ml of H with a mass fraction of 30%₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder was ground and burned in a muffle furnace at 500°M for 4 hours. And the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 4

[0028] In a 1L beaker, add 2ml of tetraisopropyl titanate, 0.0084g of stannous oxalate, and then slowly add 30ml of H with a mass fraction of 30%₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder was ground and burned in a muffle furnace at 500°M for 4 hours. And the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 5

[0030] In a 1L beaker, add 2ml of tetraisopropyl titanate, 0.0112g of stannous oxalate, and then slowly add 30ml of H with a mass fraction of 30%₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder was ground and burned in a muffle furnace at 500°M for 4 hours. And the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 6

[0032] Add 2ml of tetraisopropyl titanate and 0.0140g of stannous oxalate in a 1L beaker, and then slowly add 30ml of H with a mass fraction of 30%₂O₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder was ground and burned in a muffle furnace at 500°M for 4 hours. And the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 7

[0034] In a 1L beaker, add 2ml of tetraisopropyl titanate, 0.0056g of stannous oxalate, 0.0012g of iron acetylacetonate and then slowly add 30ml of H with a mass fraction of 30%₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder is ground and calcined in a muffle furnace for 500Ό for 4h_oAnd the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 8

[0036] In a 1L beaker, 2ml of tetraisopropyl titanate, 0.0056g of stannous oxalate, and 0.0024g of iron acetylacetonate were added to a 1L beaker and 30ml of H with a mass fraction of 30% were slowly added.₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder is ground and calcined in a muffle furnace for 500Ό for 4h_oAnd the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 9

[0038] In a 1L beaker, add 2ml of tetraisopropyl titanate, 0.0056g of stannous oxalate, 0.0119g of iron acetylacetonate, and then slowly add 30ml of H with a mass fraction of 30%.₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder is ground and placed in a muffle furnace for 500 Ό

Calcined for 4h_oAnd the obtained powder is tested for adsorption performance and photocatalytic performance.

Example 10

[0040] In a 1L beaker, 2ml of tetraisopropyl titanate, 0.0056g of stannous oxalate, and 0.0239g of iron acetylacetonate were added to a 1L beaker. After that, 30ml of H with a mass fraction of 30% was slowly added.₂0₂And turn on the stirring to make it evenly mixed, and slowly raise the temperature to 50°C, and react for half an hour. After that, the gel was placed in an oven at 120°C to dry. The dried powder is ground and calcined in a muffle furnace at 500Ό for 4h_oAnd the obtained powder is tested for adsorption performance and photocatalytic performance.

[0041] Table 1

[0042]

<td>Example</td><td>Rutile content (%)</td>

<td>1</td><td>0</td>

<td>2</td><td>28</td>

<td>3</td><td>75</td>

<td>4</td><td>100</td>

<td>5</td><td>100</td>

<td>6</td><td>100</td>

[0043] Table 1 is the XRD formula F of Examples 1 to 6_e=1/[1+0.8 is called (101) /1/110)] the calculated crystal composition. It can be found from the table that the proportion of anatase in the prepared titanium dioxide can be continuously adjusted in the range of 0% to 100%, which proves that tin can promote the transformation of titanium dioxide photocatalyst from anatase phase to rutile phase, and is added to tin. After the impurities are greater than 0.6%, the pure rutile phase is reached.

[0044] Table 2

[0045]

<td>Example</td><td>Rutile content (%)</td>

<td>3</td><td>75</td>

<td>7</td><td>78</td>

<td>8</td><td>75</td>

<td>9</td><td>77</td>

<td>10</td><td>72</td>

[0046] Table 2 is Example 3 and 7-10 according to the Spurr formula Fr = 1/[1+0.8*I_a(101)/I_E(110)] Calculated crystalline composition. It can be found from the table that the amount of iron doped with different content of iron has almost no effect on the crystal phase.