CN106944035B - A kind of oxygen self-doping layered niobium oxide powder and its preparation method and application - Google Patents

Abstract

The invention discloses an oxygen self-doping layered niobium oxide powder, a preparation method and application thereof, and belongs to the field of photocatalytic materials. The technical scheme adopted is: adding layered niobium oxide powder into H ₂ O ₂ aqueous solution, stirring and reacting, filtering, washing and drying the precipitate, and obtaining O ₂ ² - self-doped layered niobium oxide powder. The present invention utilizes the open structure characteristics of layered niobium oxides, and skillfully introduces H ₂ O ₂ molecules into the interior of layered niobium oxides (between NbO ₆ octahedral layers), so that the prepared visible light-responsive O ₂ ^2– There are a large number of Nb-O-O-coordination bonds between the NbO ₆ octahedral layers of the self-doped layered niobium oxide powder, and its band gap is 2.7-2.9eV, which can be used as a visible light photocatalyst to degrade organic pollution. The application of biochemistry and photolysis of water to produce oxygen. The method has the advantages of simple process, low energy consumption, easy control, zero discharge, suitable for mass production and the like.

Description

A kind of oxygen self-doping layered niobium oxide powder and its preparation method and application

technical field

The invention belongs to the field of photocatalytic materials, and in particular relates to an oxygen (O ₂ ^2– ) self-doped layered niobium oxide powder and a preparation method and application thereof.

Background technique

Layered niobium oxides (H ₄ Nb ₆ O ₁₇ , HNb ₃ O ₈ , H ₄ Nb ₂ O ₇ , etc.) are two-dimensional materials with an open structure composed of NbO ₆ octahedral layers and interlayer H ⁺ ions. Due to its non-toxic, stable chemical properties, and excellent photocatalytic performance under ultraviolet light, it has been widely studied as a photocatalytic material in recent years. However, the layered niobium oxide has a large band gap (Eg>3.2eV), poor visible light response ability, and cannot effectively utilize solar energy. At present, many scholars have improved the visible light catalytic performance of layered niobium oxides by means of semiconductor recombination, noble metal modification, doping, and microstructure control.

O ₂ ² – Self-doped niobium oxide, that is, niobium peroxide, is mainly used in the catalysis of organic epoxidation. However, there are very few applications in photocatalysis. Oliveira LCA et al. reported in the journal [RSC Advances, 2015, 5(55): 44567-44570] that niobium hydroxide was deposited on the surface of titanium dioxide, and then treated with hydrogen peroxide to obtain a photocatalyst with visible light response. O ₂ ² – Self-doped Niobium Hydroxide/TiO ₂ Composite Photocatalyst. At present, the method for preparing O ₂ ^2– self-doped niobium oxide is mainly obtained by treating amorphous hydrated niobium oxide with aqueous H ₂ O ₂ (Catalysis Communications, 2013, 37:85-91). (Adv. Funct. Mater. 2011, 21, 3744-3752) Firstly, H ₂ O ₂ aqueous solution reacts with butyl titanate to generate soluble titanium peroxide, and then dries to obtain titanium peroxide xerogel. However, treating crystalline niobium oxide grains with H ₂ O ₂ aqueous solution cannot produce O ₂ ^2– self-doped niobium oxides, but only some Nb-OO- coordination bonds can be formed on the surface of the grains. This is because the crystalline niobium oxide has a solid structure, and H ₂ O ₂ molecules cannot enter the interior of titanium dioxide grains.

Layered niobium oxide has a large band gap and poor visible light response ability, and the modification of layered niobium oxide is mainly achieved by solid-phase high-temperature doping or heterogeneous compounding with other semiconductors. However, these methods have slow modification speed, complex process, difficult control, and are not suitable for mass production.

Contents of the invention

In order to overcome the defects in the above-mentioned prior art, the object of the present invention is to provide an oxygen (O ₂ ^2– ) self-doped layered niobium oxide powder and its preparation method and application. The method has the advantages of simple process, low energy consumption Low, zero emission, suitable for industrial production and other advantages; the O ₂ ² - self-doped layered niobium oxide powder prepared by this method has narrow band gap and strong visible light response ability.

The present invention is realized through the following technical solutions:

The invention discloses a preparation method of O _{2 2} ^- self-doped layered niobium oxide powder, adding layered niobium oxide powder into H ₂ O ₂ aqueous solution, stirring and reacting, filtering, washing the precipitate, Dry to obtain O ₂ ^{2 -self-} doped layered niobium oxide powder.

Preferably, the layered niobium oxide powder is white niobate having a layered open structure.

Preferably, the layered niobium oxide powder is H ₄ Nb ₆ O ₁₇ , HNb ₃ O ₈ or H ₄ Nb ₂ O ₇ .

Preferably, the dosage ratio of the layered niobium oxide powder to the H ₂ O ₂ aqueous solution is (0.5-1) g: (10-100) mL.

Preferably, the mass concentration of the H ₂ O ₂ aqueous solution is 5%-30%.

Preferably, the stirring reaction time is 1-30 min.

Preferably, the precipitate is washed with deionized water; the drying temperature is 40-80°C.

The present invention also discloses the preparation of O _{2 2} ^- self-doped layered niobium oxide powder by the above method, the O _{2 2} ^- self-doped layered niobium oxide powder is yellow, and its NbO ₆ octahedral layer There are Nb-OO-coordination bonds between them, and the band gap is 2.5-2.9eV.

The present invention also discloses the application of the above-mentioned O ₂ ^{2 -self-} doped layered niobium oxide powder as a visible light photocatalyst. The O ₂ ^{2 -self-} doped layered niobium oxide powder can degrade organic pollutants and generate oxygen by photolysis of water.

Compared with the prior art, the present invention has the following beneficial technical effects:

In the preparation method of O _{2 2} ^- self-doped layered niobium oxide powder disclosed in the present invention, H ₂ O ₂ aqueous solution is used to perform O _{2 2} ^- self-doping on the layered structure niobium oxide powder. Niobium oxide has an open structure, and H ₂ O ₂ molecules can easily enter the NbO ₆ octahedral interlayer to form O ₂ ^2– self-doped layered niobium oxide, thereby reducing the band gap of the layered niobium oxide, reaching The purpose of layered niobium oxides with photocatalytic activity under visible light was achieved. Compared with solid-phase high-temperature doping modification and heterogeneous semiconductor recombination, O ₂ ^2– self-doping has the advantages of simple process, low energy consumption, easy control, zero emission, and suitable for mass production.

The present invention utilizes the open structure characteristics of layered niobium oxides, and skillfully introduces H ₂ O ₂ molecules into the interior of layered niobium oxides (between NbO ₆ octahedral layers), so that the prepared visible light-responsive O ₂ ^2– There are a large number of Nb-OO-coordination bonds between the NbO ₆ octahedral layers of the self-doped layered niobium oxide powder, and its band gap is 2.7-2.9eV, which can be used as a visible light photocatalyst to degrade organic pollutants and light. The application of decomposing water to produce oxygen.

Description of drawings

Fig. 1 is the color photo of O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention; wherein, (a) is layered H ₄ Nb ₆ O ₁₇ ; (b ) is O ₂ ² - self-doping H ₄ Nb ₆ O ₁₇ ;

Figure 2 is the XRD spectrum of O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention;

Fig. 3 is the ultraviolet-visible diffuse reflectance spectrum of O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention;

Fig. 4 is the transient photocurrent diagram of O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention;

Fig. 5 is a visible light degradation diagram of O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention on RhB dye.

Fig. 6 is a visible light degradation cycle diagram of O ₂ ^{2 -self-} doped H ₄ Nb ₆ O ₁₇ prepared in the present invention for RhB dye.

Fig. 7 is a diagram of O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention for visible photocatalytic decomposition of water to produce oxygen.

Detailed ways

The present invention will be further described in detail below in conjunction with specific examples, which are explanations of the present invention rather than limitations.

Example 1

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 0.5g: 100mL, the layered niobium oxide white powder H ₄ Nb ₆ O ₁₇ is added to the H ₂ O ₂ aqueous solution with a mass concentration of 28%, After stirring for 30 min, it was filtered, the precipitate was washed with deionized water, and dried at 40°C for 1 h to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Example 2

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 1g: 50mL, add layered niobium oxide white powder H ₄ Nb ₆ O ₁₇ into the H ₂ O ₂ aqueous solution with a mass concentration of 30%, and stir After 20 min, it was filtered, the precipitate was washed with deionized water, and dried at 80°C for 1 h to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Example 3

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 1g: 10mL, add layered niobium oxide white powder H ₄ Nb ₆ O ₁₇ into the H ₂ O ₂ aqueous solution with a mass concentration of 30%, and stir After 10 minutes, it was filtered, the precipitate was washed with deionized water, and dried at 55°C for 1 hour to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Example 4

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 1g: 100mL, add layered titanate white powder HNb ₃ O ₈ into the H ₂ O ₂ aqueous solution with a mass concentration of 20%, after stirring for 5 minutes, After filtering, the precipitate was washed with deionized water, and dried at 55°C for 1 hour to obtain yellow O ₂ ^{2 -self-} doped layered niobium oxide powder.

Example 5

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 1g:10mL, add layered niobium oxide white powder HNb ₃ O ₈ into the H ₂ O ₂ aqueous solution with a mass concentration of 20%, and stir for 5 minutes , filtered, the precipitate was washed with deionized water, and dried at 55°C for 1 h to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Example 6

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution: 1g: 20mL, add the layered niobium oxide white powder HNb ₃ O ₈ into the H ₂ O ₂ aqueous solution with a mass concentration of 5%, and stir for 2 minutes , filtered, the precipitate was washed with deionized water, and dried at 40°C for 1 h to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Example 7

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 1g:10mL, add layered niobium oxide white powder H ₄ Nb ₂ O ₇ into the H ₂ O ₂ aqueous solution with a mass concentration of 5%, After stirring for 1 min, it was filtered, the precipitate was washed with deionized water, and dried at 80°C for 1 h to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Example 8

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 1g:10mL, add layered niobium oxide white powder H ₄ Nb ₂ O ₇ into the H ₂ O ₂ aqueous solution with a mass concentration of 5%, After stirring for 1 min, it was filtered, the precipitate was washed with deionized water, and dried at 60°C for 1 h to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Example 9

According to the dosage of layered niobium oxide and H ₂ O ₂ aqueous solution is 1g:10mL, add layered niobium oxide white powder H ₄ Nb ₂ O ₇ into the H ₂ O ₂ aqueous solution with a mass concentration of 5%, After stirring for 1 min, it was filtered, the precipitate was washed with deionized water, and dried at 80°C for 1 h to obtain yellow O ₂ ^2– self-doped layered niobium oxide powder.

Referring to Figure 1, it can be seen from Figure 1 that the powder in (a) is white, and the O ₂ ² - self-doped H ₄ Nb ₆ O ₁₇ in (b) is yellow. See Figure 2. It can be seen from Figure 2 that all the diffraction peaks of the layered niobium oxide are basically consistent with O _{2 2} ^– self-doped H ₄ Nb ₆ O ₁₇ , indicating that the layered structure after hydrogen peroxide treatment is not the same as before the treatment. Change, only the diffraction peak on the (040) crystal plane shifted from 10.33° to 9.54° to the left, and the corresponding NbO ₆ octahedral interlayer spacing expanded from 0.857nm to 0.927nm, indicating that hydrogen peroxide entered the interlayer, making the interlayer spacing increase. big. Fig. 3 is the ultraviolet-visible diffuse reflectance spectrum of O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention. It can be seen from Fig. 3 that O _{2 2} ^- self-doped H ₄ Nb ₆ O ₁₇ can effectively absorb visible light, and the light absorption band edge is 565nm, that is, the forbidden band width is 2.7eV. Figure ₄ is the transient photocurrent diagram of O ₂ ^{2 -self- doped} H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention _; Nb ₆ O ₁₇ can effectively promote the efficient separation of photogenerated electrons-holes. Fig. 5 is the visible light degradation diagram of O _{2 2} ^{- self} -doped H ₄ Nb ₆ O ₁₇ and layered H ₄ Nb ₆ O ₁₇ prepared by the present invention on RhB dye _{; 4} Nb ₆ O ₁₇ has visible-light photocatalytic properties, while layered niobium oxides do not. Fig. 6 is the visible light degradation cycle diagram of O ₂ ² - self-doped H ₄ Nb ₆ O ₁₇ prepared by the present invention to RhB dye; from Fig. 6, it can be seen that O ₂ ² - self-doped H ₄ Nb ₆ O ₁₇ has good cycle stability. Figure 7 is a diagram of O ₂ ^{2 -self-} doped H ₄ Nb ₆ O ₁₇ produced by the present invention by visible light decomposition of water for oxygen production; from Figure 7, it can be seen that O ₂ ^{2 -self-} doped H ₄ Nb ₆ O ₁₇ has the performance of visible light decomposition of water for oxygen production , and the oxygen production rate was 13 μmol·g ^-1 .

The above-mentioned content is a further detailed description of the present invention in combination with specific preferred embodiments, not all or the only embodiments, and any equivalent transformation adopted by those of ordinary skill in the art to the technical solution of the present invention by reading the description of the present invention, All are covered by the claims of the present invention.

Claims (8)

1. A preparation method of O _{2 2} ^- self-doped layered niobium oxide powder, characterized in that the layered niobium oxide powder is added into H ₂ O ₂ aqueous solution, stirred and reacted, filtered, and precipitated Washing and drying to obtain O _{2 2} ^- self-doped layered niobium oxide powder; The layered niobium oxide powder is H ₄ Nb ₆ O ₁₇ , HNb ₃ O ₈ or H ₄ Nb ₂ O ₇ powder with a layered open structure; The prepared O ₂ ² - self-doped layered niobium oxide powder has Nb-OO- coordination bonds between NbO ₆ octahedral layers, and its forbidden band width is 2.5-2.9 eV. 2. O ₂ according to claim 1 - the preparation method of self ^- doping layered niobium oxide powder, characterized in that, the amount ratio of the layered niobium oxide powder and H ₂ O ₂ aqueous solution is (0.5～1)g: (10～100)mL. 3 . The method for preparing O ₂ ^{2 -self-} doped layered niobium oxide powder according to claim 1 or 2, characterized in that the mass concentration of the H ₂ O ₂ aqueous solution is 5%-30%. 4 . The method for preparing O ₂ ^{2 -self-} doped layered niobium oxide powder according to claim 1 , characterized in that the stirring reaction time is 1-30 min. 5. The method for preparing O _{2 2} ^- self-doped layered niobium oxide powder according to claim 1, characterized in that the precipitation is washed with deionized water; the drying temperature is 40-80°C. 6. The O _{2 2} ^- self-doped layered niobium oxide powder prepared by the method according to any one of claims 1 to 5, characterized in that the O ₂ ² -self-doped layered niobium oxide powder The powder is yellow in color. 7. The application of the O _{2 2} ^- self-doped layered niobium oxide powder as claimed in claim 6 as a visible light photocatalyst. 8 . The application according to claim 7 , wherein the O ₂ ^{2 -self-} doped layered niobium oxide powder can degrade organic pollutants and produce oxygen by photolysis of water.