阅读说明：本技术 一种富氧缺陷Bi2O4光催化材料及其制备方法和用途 (Oxygen-enriched defect Bi2O4Photocatalytic material, preparation method and application thereof ) 是由 杨若凡 胡长员 于 2021-09-13 设计创作，主要内容包括：本发明公开了一种富氧缺陷Bi-(2)O-(4)光催化材料及其制备方法和用途,所述方法包括：(1)将NaBiO-(3)·2H-(2)O经煅烧或者在碱性溶液中进行水热反应,得到中间产物NaBiO-(3)·xH-(2)O,其中,1<x<2；(2)将步骤(1)的中间产物NaBiO-(3)·xH-(2)O进行水热反应,生成富氧缺陷的Bi-(2)O-(4)。本发明制备的材料中氧缺陷浓度高,导致其光生电子-空穴对的产生和分离效率高,从而大幅度提高了四氧化二铋的可见光催化性能。(The invention discloses an oxygen-enriched defect Bi 2 O 4 Photocatalytic material and a method for its preparation and use, the method comprising: (1) mixing NaBiO 3 ·2H 2 Calcining O or carrying out hydrothermal reaction in an alkaline solution to obtain an intermediate product NaBiO 3 ·xH 2 O, wherein 1<x<2; (2) the intermediate product NaBiO in the step (1) 3 ·xH 2 Performing hydrothermal reaction on O to generate Bi with oxygen-enriched defects 2 O 4 . The material prepared by the invention has high oxygen defect concentration, so that the material can generate photoproduction electron-spaceThe generation and separation efficiency of the hole pairs is high, so that the visible light catalytic performance of the bismuth tetroxide is greatly improved.)

1. Bi with oxygen-enriched defects₂O₄A method for preparing a photocatalytic material, comprising the steps of:

(1) mixing NaBiO₃·2H₂Calcining O or carrying out hydrothermal reaction in an alkaline solution to obtain an intermediate product NaBiO₃·xH₂O, wherein 1<x<2；

(2) The intermediate product NaBiO in the step (1)₃·xH₂Performing hydrothermal reaction on O to generate Bi with oxygen-enriched defects₂O₄。

2. The method according to claim 1, characterized in that it comprises in particular the steps of:

(1A) mixing NaBiO₃·2H₂Mixing O with alkaline solution, and carrying out hydrothermal reaction to generate intermediate-containing NaBiO₃·xH₂An aqueous solution of O;

or (1B) adding NaBiO₃·2H₂Calcining O to generate intermediate product NaBiO₃·xH₂O；

(2) The intermediate product NaBiO obtained in the step (1A) or (1B)₃·xH₂Mixing O with water, and carrying out hydrothermal reaction to generate Bi containing oxygen-rich defects₂O₄An aqueous solution of (a).

3. The method according to any one of claims 1-2, wherein in step (1), the alkaline solution is a strong alkaline solution, such as an aqueous solution of NaOH or KOH, and the concentration of the alkaline solution is 6M to 10M.

4. The method according to any one of claims 1 to 3, wherein in step (1), NaBiO is used₃·2H₂The molar ratio of O to the alkaline solution is 1 (10-20).

Preferably, in step (1), NaBiO₃·2H₂D of O₅₀5 to 10 μm.

5. The method as claimed in any one of claims 1 to 4, wherein the hydrothermal reaction temperature in step (1) is 150 ℃ and 250 ℃, such as 160 ℃ and 220 ℃.

Preferably, in the step (1), the hydrothermal reaction time is 6-12 h.

6. The method as claimed in any one of claims 1 to 5, wherein the temperature of the calcination in step (1) is 150 ℃ and 250 ℃, such as 160 ℃ and 220 ℃.

Preferably, in step (1), the calcination time is 0.5-2 h.

7. According to claim1-6, wherein in step (2), water is mixed with the intermediate NaBiO₃·xH₂The mass ratio of O is (10-100): 1.

8. The method as claimed in any one of claims 1 to 7, wherein the hydrothermal reaction temperature in step (2) is 150 ℃ and 250 ℃, such as 160 ℃ and 220 ℃.

Preferably, in the step (2), the hydrothermal reaction time is 12-20 h.

9. Oxygen-enriched defective Bi prepared by the method of any one of claims 1 to 8₂O₄A photocatalytic material.

10. The oxygen-rich defective Bi of claim 9₂O₄The application of the photocatalyst is characterized in that the photocatalyst is applied to the catalytic degradation of organic pollutants under visible light.

Preferably, the organic contaminants are acid dyes or phenolic dyes, more preferably methyl orange and phenol.

Technical Field

The present invention relates to a photocatalytic materialAnd preparation and application thereof, in particular to a Bi-deficient oxygen-enriched material₂O₄Photocatalytic material, preparation method and application thereof.

Background

With the development of chemical industry, environmental pollution is becoming more serious. The discharge of printing and dyeing wastewater is one of the important causes of water pollution. Every year, a large amount of commercial dyes are discharged, and the dyes are stable in chemical property and cause great damage to the ecological environment. The characteristic that the semiconductor oxide material can be activated under the irradiation of sunlight is utilized, organic matters can be effectively oxidized and degraded into carbon dioxide, water and other small molecules, and the process has the advantages of mild reaction conditions, no secondary pollution, simplicity in operation, obvious degradation effect and the like. Therefore, semiconductor photocatalytic materials with excellent properties are the hot spot of current research. Wherein Bi₂O₄Has the advantages of low toxicity, low cost, durability, super-hydrophilicity and the like, and is one of the commonly used semiconductor photocatalytic materials at present. However, the prior art is to mix NaBiO₃ ^.2H₂Adding O into the water solution, stirring, and carrying out hydrothermal reaction to generate Bi₂O₄. This process gives Bi₂O₄The oxygen defects are few, so that the generation and separation efficiency of the photo-generated electron-hole pairs is low, and the visible light catalysis performance is poor.

Disclosure of Invention

In order to improve the problems, the invention provides an oxygen-rich defect Bi₂O₄Photocatalytic material, preparation method and application thereof. The invention firstly prepares NaBiO₃ ^.2H₂O is converted into an intermediate product, and then the intermediate product is subjected to hydrothermal reaction to generate Bi with oxygen-rich defects₂O₄。

The technical scheme of the invention is as follows:

bi with oxygen-enriched defects₂O₄A method of preparing a photocatalytic material, the method comprising the steps of:

(1) mixing NaBiO₃·2H₂Calcining O or carrying out hydrothermal reaction in an alkaline solution to obtain an intermediate product NaBiO₃·xH₂O, wherein 1<x<2；

(2) The intermediate product NaBiO in the step (1)₃·xH₂Performing hydrothermal reaction on O to generate Bi with oxygen-enriched defects₂O₄。

According to the invention, the method comprises in particular the following steps:

(1A) mixing NaBiO₃·2H₂Mixing O with alkaline solution, and carrying out hydrothermal reaction to generate intermediate-containing NaBiO₃·xH₂An aqueous solution of O; or (1B) adding NaBiO₃·2H₂Calcining O to generate intermediate product NaBiO₃·xH₂O；

(2) The intermediate product NaBiO obtained in the step (1A) or (1B)₃·xH₂Mixing O with water, and carrying out hydrothermal reaction to generate Bi containing oxygen-rich defects₂O₄An aqueous solution of (a).

According to an embodiment of the invention, the method further comprises the steps of:

(3) and (3) carrying out solid-liquid separation on the aqueous solution obtained in the step (1A) or the step (2) to obtain a solid, washing the solid to be neutral by using water, and drying.

According to an embodiment of the present invention, in the step (1), the alkaline solution is a strong alkaline solution, such as an aqueous solution of NaOH or KOH, and the concentration of the alkaline solution is 6M to 10M; for example, it may be 6M, 7M, 8M, 9M or 10M.

According to an embodiment of the invention, in step (1), NaBiO₃·2H₂The molar ratio of O to the alkaline solution is 1 (10-20).

According to an embodiment of the invention, in step (1), NaBiO₃·2H₂D of O₅₀5 to 10 μm.

According to the embodiment of the invention, in the step (1), the hydrothermal reaction temperature is 150-250 ℃, such as 160-220 ℃, and exemplary is 160 ℃, 180 ℃, 200 ℃ or 220 ℃.

According to an embodiment of the present invention, in step (1), the hydrothermal reaction time is 6 to 12 hours, exemplary 6 hours, 7 hours, 8 hours, 10 hours, or 12 hours.

According to an embodiment of the present invention, in step (1), the temperature of the calcination is 150-250 ℃, such as 160-220 ℃, and is illustratively 160 ℃, 180 ℃, 200 ℃ or 220 ℃.

According to an embodiment of the invention, in step (1), the calcination time is 0.5 to 2h, exemplary 0.5h, 1h, 1.5h or 2 h.

According to the embodiment of the invention, in the steps (1) and (2), a stirring and mixing manner can be adopted to ensure that the mixing is uniform, wherein the stirring time is 10-30min, and the stirring speed is 1000-1500 r/min.

According to an embodiment of the invention, in step (2), water is reacted with the intermediate NaBiO₃·xH₂The mass ratio of O is (10-100):1, preferably (15-65): 1.

According to the embodiment of the invention, in the step (2), the hydrothermal reaction temperature is 150-250 ℃, such as 160-220 ℃, and exemplary is 160 ℃, 170 ℃, 180 ℃, 190 ℃ or 200 ℃.

According to an embodiment of the present invention, in step (2), the hydrothermal reaction time is 12 to 20h, exemplified by 12h, 14h, 15h, 16h, 18h or 20 h.

According to the embodiment of the present invention, in the step (3), the solid-liquid separation can be performed by means known in the art, such as filtration, suction filtration or centrifugation, to obtain a solid, which is washed with water to be neutral, and finally dried in an oven for 6-12 h. For example, the drying temperature is 50 to 80 ℃.

The invention also provides the Bi with oxygen-enriched defects prepared by the method₂O₄A photocatalytic material.

The invention also provides Bi with the oxygen-rich defect₂O₄Use of a photocatalyst for the catalytic degradation of organic contaminants under visible light.

According to an embodiment of the present invention, the organic contaminants may be acid dyes or phenolic dyes, exemplified by methyl orange and phenol.

Advantageous effects

(1) Firstly, NaBiO is mixed with the mixture₃·2H₂O is converted into NaBiO by calcining or hydrothermal reaction in alkaline solution₃·xH₂O intermediate product, then further hydrothermal reaction is carried out to generate Bi₂O₄. The material prepared by the method has high oxygen defect concentration, so that the generation and separation efficiency of the photoproduction electron-hole pair is high, and the visible light catalytic performance of the bismuth tetroxide is greatly improved.

(2) Bi prepared by the invention₂O₄The degradation efficiency of the organic pollutants under the visible light catalysis condition can reach 95.5 percent at most.

Drawings

FIG. 1 shows the intermediate products and NaBiO prepared in examples 1 and 3₃·2H₂XRD pattern of O.

FIG. 2 shows Bi prepared in example 1 and comparative example 1₂O₄XRD pattern of (a).

FIG. 3 shows Bi prepared in example 1 and comparative example 1₂O₄Electron paramagnetic resonance spectrum of (a).

FIG. 4 shows Bi prepared in example 1 and comparative example 1₂O₄Degradation performance of methyl orange under irradiation of visible light.

FIG. 5 shows Bi prepared in example 1 and comparative example 1₂O₄Degradation performance of phenol under the irradiation of visible light.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

Example 1

1.26g NaBiO₃·2H₂O was dispersed in 70mL of NaOH (10M) aqueous solution, stirred (1100r/min) for 30 minutes, and then the suspension was transferred to a 100mL polytetrafluoroethylene liner and placed in the reaction vessel. And finally, placing the reaction kettle into an oven to be heated to 180 ℃ and reacting for 6 h. Naturally cooling to room temperatureThen, the obtained sample is filtered, washed to be neutral by deionized water and dried in an oven at 60 ℃ for 12 hours to obtain an intermediate product NaBiO₃·xH₂O, wherein 1<x<2。

1.68g of the intermediate powder was dispersed in 60mL of water, stirred (1100r/min) for 30 minutes, and the suspension was transferred to a 100mL polytetrafluoroethylene liner and placed in the reaction vessel. And finally, placing the reaction kettle into an oven to be heated to 180 ℃ and reacting for 12 h. After naturally cooling to room temperature, filtering the obtained sample, washing the sample to be neutral by deionized water, and drying the sample in a 60 ℃ oven for 12 hours to obtain Bi with oxygen-enriched defects₂O₄A photocatalyst. The degradation efficiency of methyl orange and phenol under the visible light catalysis condition is 95.5 percent and 88.6 percent respectively.

Example 2

1.5g NaBiO₃ ^.2H₂O was dispersed in 70mL of NaOH (8M) aqueous solution, stirred (1200r/min) for 20 minutes, and then the suspension was transferred to a 100mL polytetrafluoroethylene liner and placed in the reaction vessel. And finally, putting the reaction kettle into an oven, heating to 200 ℃, and reacting for 7 hours. After naturally cooling to room temperature, carrying out suction filtration on the obtained sample, washing the sample to be neutral by using deionized water, and drying the sample in a 60 ℃ oven for 12 hours to obtain an intermediate product NaBiO₃·xH₂O, wherein 1<x<2。

2g of the intermediate powder are dispersed in 60mL of water and, after stirring (1100r/min) for 30 minutes, the suspension is transferred into a 100mL polytetrafluoroethylene liner and placed in the reaction vessel. And finally, placing the reaction kettle into an oven to be heated to 160 ℃, and reacting for 15 h. After naturally cooling to room temperature, filtering the obtained sample, washing the sample to be neutral by deionized water, and drying the sample in a 60 ℃ oven for 12 hours to obtain Bi with oxygen-enriched defects₂O₄A photocatalyst. The degradation efficiency of methyl orange and phenol under the visible light catalysis condition is 94.6 percent and 87.5 percent respectively.

Example 3

Mixing NaBiO₃ ^.2H₂Placing O in a watch glass, and then placing the watch glass into a muffle furnace for calcination (at 200 ℃, 0.5h) to obtain an intermediate product NaBiO₃·xH₂O, wherein 1<x<2。

1g of the intermediate product was dispersed in 60mL of water, stirred (1100r/min) for 30 minutes, and the suspension was transferred to a 100mL polytetrafluoroethylene liner and placed in the reaction vessel. And finally, placing the reaction kettle into an oven to be heated to 160 ℃, and reacting for 12 h. After naturally cooling to room temperature, filtering the obtained sample, washing the sample to be neutral by deionized water, and drying the sample in a 60 ℃ oven for 12 hours to obtain Bi with oxygen-enriched defects₂O₄The degradation efficiency of the photocatalyst on methyl orange and phenol under the visible light catalysis condition is 82.4 percent and 78.6 percent respectively.

Example 4

1.4g NaBiO₃·2H₂O was dispersed in 70mL KOH (8M) aqueous solution, stirred (1200r/min) for 20 minutes, and then the suspension was transferred to a 100mL Teflon liner and placed in the reactor. And finally, putting the reaction kettle into an oven, heating to 200 ℃, and reacting for 7 hours. After naturally cooling to room temperature, carrying out suction filtration on the obtained sample, washing the sample to be neutral by using deionized water, and drying the sample in a 60 ℃ oven for 12 hours to obtain an intermediate product NaBiO₃·xH₂O, wherein 1<x<2。

2g of the intermediate product are dispersed in 60mL of water, stirred (1100r/min) for 30 minutes, and the suspension is transferred to a 100mL polytetrafluoroethylene liner and placed in the reaction vessel. And finally, placing the reaction kettle into an oven to be heated to 160 ℃, and reacting for 15 h. After naturally cooling to room temperature, filtering the obtained sample, washing the sample to be neutral by deionized water, and drying the sample in a 60 ℃ oven for 12 hours to obtain Bi with oxygen-enriched defects₂O₄The degradation efficiency of the photocatalyst on methyl orange and phenol under the visible light catalysis condition is 94.4 percent and 87.2 percent respectively.

Comparative example

1.68g of NaBiO is taken₃·2H₂O powder was dispersed in 60mL of water, stirred (1100r/min) for 30 minutes, and then the suspension was transferred to a 100mL polytetrafluoroethylene liner and placed in the reaction vessel. And finally, placing the reaction kettle into an oven to be heated to 180 ℃ and reacting for 12 h. After naturally cooling to room temperature, filtering the obtained sample, washing the sample to be neutral by deionized water, and drying the sample in a 60 ℃ oven for 12 hours to obtain Bi₂O₄A photocatalyst is used as a light source for the light,the degradation efficiency of methyl orange and phenol under the visible light catalysis condition is 45.6 percent and 34.5 percent respectively.

Analyzing the phase structure of the material by adopting an X-ray powder diffractometer; and analyzing the oxygen defect concentration of the material by adopting an electron paramagnetic resonance spectrometer.

The method for measuring the efficiency of the catalyst for degrading organic pollutants by photocatalysis comprises the following steps:

in the experimental process, methyl orange and phenol are used as pollutants to be degraded, and a photocatalytic degradation reaction is carried out in an XPA-7 photocatalytic reactor. The visible light source is a 500W Xe lamp and a 420nm filter.

The specific operation process is as follows: 24mg of the catalysts prepared in examples 1 to 4 and comparative example were dispersed in 58mL of the solution to be degraded and vigorously stirred under dark conditions for 60min to reach adsorption-desorption equilibrium. The light source was then turned on and after a certain time interval 4mL of suspension were taken and the solid photocatalyst was removed by 0.22 μm filtration to give a degraded solution and the absorbance of the solution was measured with a UV-vis spectrophotometer. According to lambert-beer's law: where ε is a constant, it can be seen that the absorbance of the solution is directly proportional to the concentration, i.e. A/A₀＝C/C₀And is used to indicate the degree of degradation of the target contaminant.

FIG. 1 shows the intermediate products and NaBiO prepared in examples 1 and 3₃ ^.2H₂XRD pattern of O. From FIG. 1, NaBiO is shown₃·2H₂Intermediate products generated by hydrothermal reaction or low-temperature calcination of O (JCPDS No.30-1161) in alkaline solution are NaBiO₃·xH₂O (JCPDS No.30-1160), wherein, 1<x<2。

FIG. 2 shows Bi prepared in example 1 and comparative example 1₂O₄XRD pattern of (a). From FIG. 2 it can be seen that the use of NaBiO₃·2H₂The intermediate product generated by O conversion is subjected to hydrothermal reaction and raw material NaBiO is used₃·2H₂The materials generated by direct hydrothermal of O are all Bi₂O₄(JCPDS No.50–0864)。

FIG. 3 shows Bi prepared in example 1 and comparative example 1₂O₄Electron paramagnetic resonance spectrum of (a). From FIG. 3, Bi prepared in example 1 is seen₂O₄Has an oxygen vacancy concentration far greater than that of Bi prepared in comparative example 1₂O₄。

FIG. 4 shows Bi prepared in example 1 and comparative example 1₂O₄Degradation performance of methyl orange under irradiation of visible light. As can be seen from FIG. 4, Bi prepared in example 1 was irradiated for 70min with visible light₂O₄The degradation efficiency for methyl orange was 95.5%, compared to Bi prepared in comparative example 1₂O₄The degradation efficiency on methyl orange is 45.6%.

FIG. 5 shows Bi prepared in example 1 and comparative example 1₂O₄Degradation performance of phenol under the irradiation of visible light. As can be seen from FIG. 5, Bi prepared in example 1 was irradiated with visible light for 70min₂O₄The degradation efficiency for phenol was 88.6%, compared to Bi prepared in comparative example 1₂O₄The degradation efficiency for phenol was 34.5%. Thus showing that Bi prepared by the invention₂O₄The semiconductor photocatalytic material has good degradation efficiency on organic pollutants under the visible light catalysis condition.

The embodiments of the present invention have been described above by way of example. However, the scope of the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement and the like made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.